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Determining Suitable Settings Auto Recloseing.
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DETERMINING SUITABLE SETTINGS FOR AUTO
RECLOSING SCHEMES OF THE SRI LANKAN
TRANSMISSION SYSTEM
G.R.H.U. Somapriya
08/8321
Degree of Master of Science
Department of Electrical Engineering
University of Moratuwa
Sri Lanka
September 2012
DETERMINING SUITABLE SETTINGS FOR AUTO
RECLOSING SCHEMES OF THE SRI LANKAN
TRANSMISSION SYSTEM
Gama Ralalage Harshana Udayakumara Somapriya
08/8321
Dissertation submitted in partial fulfillment of the requirements for the
Degree Master of Science in Electrical Installations
Supervised by: Dr.K.T.M.Udayanga Hemapala
Department of Electrical Engineering
University of Moratuwa
Sri Lanka
September 2012
i
DECLARATION “I declare that this is my own work and this dissertation does not incorporate without
acknowledgement any material previously submitted for a Degree or Diploma in any
other University or institute of higher learning and to the best of my knowledge and
belief it does not contain any material previously published or written by another
person except where the acknowledgement is made in the text.
Also, I hereby grant to University of Moratuwa the non-exclusive right to reproduce
and distribute my dissertation, in whole or in part in print, electronic or other
medium. I retain the right to use this content in whole or part in future works (such as
articles or books)”.
Signature of the candidate Date:
(G.R.H.U. Somapriya)
The above candidate has carried out research for the Masters Dissertation under my
supervision.
Signature of the supervisor Date:
(Dr. K.T.M. Udayanga Hemapala)
ii
ABSTRACT
The majority of faults in the transmission network can be successfully cleared by the proper use of protective relays to trip the respective circuit breakers and to bring back the system to normalcy using high speed autoreclosing. Thus, autoreclosing can significantly reduce the outage time due to faults and provide a higher level of service continuity to the customer. Furthermore, successful high-speed reclosing on transmission circuits can be a major factor when attempting to maintain system stability during fault clearing. Initial studies revealed that a detailed study of Autoreclosing settings in the transmission network of Ceylon Electricity Board and their performance based on failure analysis has not been carried out since the review of the protection system and settings by Lahmeyer International in 1996. Further there has been a brief analysis by the PB power consultants in their report on the CEB transmission system and organizational arrangements for operation and maintenance in October 1999. Since then there has been a comprehensive expansion of the CEB transmission network. Existing settings were reviewed along with failure incidents recorded during the period of November 2006 to August 2012 in the selected transmission lines. The stability analysis was carried out with the existing settings and prospective settings using the existing CEB power system which is modeled in PSSE software. Based on the simulated results, analysis of failure incidents, review of existing settings and the literature available on the practices followed in determining Auto reclose settings a set of Auto reclose settings for 220kV and 132kV transmission lines were proposed. These new settings and recommendations will improve the AR success rate thereby improving the reliability of the network. It will also minimize the risk of major failures resulted due to the definitive tripping of important transmission lines due to transient faults. Key words: Auto reclosing, Transmission lines, Simulations, Failure analysis.
iii
ACKNOWLEDGEMENT
First, I pay my sincere gratitude to Dr. K.T.M. Udayanga Hemapala who encouraged
and guided me to conduct this investigation and on perpetration of final dissertation.
I extend my sincere gratitude to Prof. J.P. Karunadasa, Head of the Department of
Electrical Engineering and to the staff of the Department of Electrical Engineering
for the support extended during the study period. My mind runs to the golden days
when we studied various subjects of Electrical Engineering under the wonderful
guidance of Prof. Rohan Lucas, Prof. Ranjith Perera, Dr. Narendra De Silva, Dr.
Priyantha Wijethunga and Dr. Thilak Siyambalapitiya among many others.
My special thanks go to Mr. Jayasiri Karunanayake who helped me select this topic
and guided me patiently whenever I approached him for advice.
I would like to express my deep gratitude to Eng. Eranga Kudahewa who gave the
valuable instructions during the simulations and spent a lot of valuable time in
helping me.
I would like to take this opportunity to extend my sincere thanks to Mr.D.D.K.
Karunarathne, Deputy General Manager (TD & E), Mr.T.D.Handagama, Deputy
General Manager (System Control), Mr.N.S.Wettasinghe, Chief Engineer (Protection
Development Section), Mr.D.S.R.Alahakoon, Chief Engineer (System Operations),
Mr. J.Nanthakumar Chief Engineer (Operation Planning), Mr. Nadun Chamikara,
Electrical Engineer (Protection Development Section) and all the Office Staff of
Protection Development Section of Ceylon Electricity Board who gave their co-
operation to conduct my investigation work successfully.
It is a great pleasure to remember the kind co-operation and motivation provided by
the family and the friends and specially my wife Dilhani who helped me to continue
the studies from start to end.
iv
TABLE OF CONTENTS
Declaration of the candidate & Supervisor i
Abstract ii
Acknowledgements iii
Table of Content iv
List of Figures vii
List of Tables viii
List of Abbreviations ix
List of Appendices x
1. Introduction 1
1.1 Background 1
1.2 Identification of the problem 2
1.3 Objective of the Study 2
1.4 Importance of the study 3
1.5 Methodology 3
2. Principles of Autoreclosing 4
2.1 Theory of Autoreclosing 4
2.2 Basis for the analysis of Stability using software models 8
2.3 PSSE Simulation Software & Network Model 8
3. Review of existing settings and failure analysis 10
3.1 Existing Auto Reclosing Settings of 220kV Lines 10
3.1.1 Summary of existing settings 10
3.1.1.1 Single and three phase AR 11
3.1.1.2 Dead Times 12
3.1.1.3 Synchro Check Condition 12
3.1.1.4 Single Shot and Multi Shot AR 13
3.1.2 Analysis of previous failure incidents of 220kV system 13
3.1.2.1 Failure incidents of Biyagama - Kothmale lines 13
3.1.2.2 Failure incidents of Veyangoda - Norochcholai lines 16
3.2 Existing Auto Reclosing Settings of 132kV Lines 19
3.2.1 Review of settings of 132kV system 1 20
3.2.2 Review of settings of 132kV system 2 22
3.2.3 Analysis of previous failure incidents of 132kV system 23
v
4. Stability Analysis 24
4.1 Three phase Autoreclose of 220kV lines 24
4.1.1 Biyagama – Kothmale 220kV lines 24
4.1.1.1 Simulation of 3ph AR for a dead time of 5s 24
4.1.1.2 Simulation of 3ph AR for a dead time of 1.2s 26
4.1.1.3 Simulation of 3ph AR for a dead time of 1s 27
4.1.1.4 Simulation of 3ph AR for a dead time of 750ms 28
4.1.1.5 Simulation of 3ph AR for a dead time of 500ms 29
4.1.1.6 Simulation of 3ph AR for a dead time of 300ms 30
4.1.2 Veyangoda – Norochcholai 220kV lines 31
4.1.2.1 Simulation of 3ph AR for a dead time of 750ms 31
4.2 Single phase Autoreclose of 220kV lines 33
4.2.1 Biyagama – Kothmale 220kV lines 33
4.2.1.1 Simulation of 1ph AR for a dead time of 450ms 33
4.2.2 Veyangoda – Norochcholai 220kV lines 35
4.2.2.1 Simulation of 1ph AR for a dead time of 800ms 35
4.3 Autoreclose of 132kV lines 36
4.3.1 AR of Balangoda – New Laxapana with dead time of 300ms 36
4.3.2 AR of Balangoda – New Laxapana with dead time of 500ms 37
4.3.3 AR of Balangoda – New Laxapana with dead time of 1.2s 38
4.3.4 AR of Balangoda – New Laxapana with dead time of 800ms 39
4.4 Effects of Autoreclose on generators 40
4.4.1 Three phase autoreclose 40
4.4.2 Single phase autoreclose 41
5. Conclusion and Recommendations 42
5.1 AR of 220kV Transmission Lines 42
5.2 AR of 132kV Transmission Lines 43
5.3 AR of generators 44
6. Conclusion and Recommendations 47
6.1 Recommended settings for 220kV Transmission Lines 47
6.2 Recommended settings for 132kV Transmission Lines 47
6.3 AR of generators 48
Reference List 49
vi
Appendix A: Failure incidents of Biyagama – Kothmale lines 51
Appendix B: Failure incidents of Veyangoda – Norochcholai lines. 53
Appendix C: AR status of 132kV transmission lines 54
Appendix D: Load Flow Network Diagram 62
vii
LIST OF FIGURES
Page
Figure 2.1 Application of the Equal-Area Criterion for Stability to the Reclosing of a Single-Circuit Tie Between Systems A and B.
6
Figure 2.2 Response of a four machine system during a transient 8
Figure 2.3 Snap shot of Biyagama – Kothmale transmission line modeled in PSSE
9
Figure 3.1 Digital Disturbance Record of Kelanitissa GIS 15
Figure 3.2 Frequency Plot for the major failure on 28th April 2008 at 17.28 hrs 16
Figure 3.3 Digital Disturbance Record for Veyangoda – Norochcholai line 1 19
Figure 3.4 Digital Disturbance Record for Norochcholai - Veyangoda line 1 20
Figure 3.5 Autoreclose scheme of 132kV network 1 21
Figure 3.6 Autoreclose scheme of 132kV network 2 22
Figure 3.7 Unsuccessful AR incident in Polpitiya Seethawaka line 23
Figure 3.8 Successful AR incident in Polpitiya Seethawaka line 23
Figure 4.1 Relative rotor angle vs Time for a dead time of 5s 25
Figure 4.2 Power Angle Curve for Kothmale Generator 26
Figure 4.3 Relative rotor angle vs Time for a dead time of 1.2s 27
Figure 4.4 Relative rotor angle vs Time for a dead time of 1s 28
Figure 4.5 Relative rotor angle vs Time for a dead time of 750ms 29
Figure 4.6 Relative rotor angle vs Time for a dead time of 500ms 30
Figure 4.7 Relative rotor angle vs Time for a dead time of 300ms 31
Figure 4.8 Rotor angle vs Time for a dead time of 750ms (Veyangoda – Noro.) 32
Figure 4.9 Relative rotor angle vs Time for a dead time of 750ms (Vey.– Noro.) 33
Figure 4.10 Rotor angle vs Time for a dead time of 450ms (1 ph. AR Biya.-Kothmale)
34
Figure 4.11 Relative rotor angle vs Time for a dead time of 450ms (1 ph. AR Biya.-Kothmale)
35
Figure 4.12 Relative rotor angle vs Time for a dead time of 450ms (1 ph. AR Vey.-Nor.)
36
Figure 4.13 Relative rotor angle vs Time for a dead time of 300ms (Lax. – Bal.) 37
Figure 4.14 Relative rotor angle vs Time for a dead time of 500ms (Lax. – Bal.) 38
Figure 4.15 Relative rotor angle vs Time for a dead time of 1.2s (Lax. – Bal.) 39
Figure 4.16 Relative rotor angle vs Time for a dead time of 800ms(Pan. – Math) 40
Figure 4.17 Power angle curve of Victoria Generators for 3ph AR of Biyagama Kothmale lines dead time 1.2s
40
Figure 4.18 Power angle curve of Victoria Generators for 1ph AR of Biyagama Kothmale lines dead time 450ms
41
viii
LIST OF TABLES
Page
Table 3.1 Existing 220kV Auto reclose settings 11
Table 3.2 Synchro check conditions 12
Table 3.3 AR settings of Kolonnawa – Athurugiriya and Polpitiya – Seethawaka Lines
21
Table 3.4 Auto reclose settings of Pannipitiya- Panadura – Horana system 22
Table 5.1 Proposed Auto reclose settings for Biyagama – Kothmale and
Veyangoda – Norochcholai 220kV lines
40
Table 6.1 Recommended AR settings for 220kV transmission lines 47
Table 6.2 Recommended AR settings for interconnected 132kV transmission
lines
48
Table 6.3 Recommended AR settings for 132kV transmission lines connecting
two isolated networks
48
ix
LIST OF ABBREVATIONS Abbrevation Description
CEB Ceylon Electricity Board
PSSE Power System Simulator for Engineering
AR Auto Reclosing
KCCP Kelanithissa Combined Cycle Plant
EDG Emergency Diesel Generator
SSR Subsynchronous Resonant Oscillations
HSR High Speed Reclosing
DDR Digital Disturbance Recorder
x
LIST OF APPENDICES Page
Appendix A Failure incidents of Biyagama – Kothmale lines 51
Appendix B Failure incidents of Veyangoda – Norochcholai lines. 53
Appendix C AR status of 132kV transmission lines 54
Appendix D Load Flow Network Diagram 62
Page 1 of 50
Chapter 1
INTRODUCTION
1.1. Background
Various studies have shown that approximately 90%, of faults on most overhead
transmission lines are transient [1, 2, 3]. A transient fault, such as an insulator
flashover, is a fault which is cleared by the immediate tripping of one or more circuit
breakers to isolate the fault, and which does not recur when the line is re-energized.
Lightning is the most common cause of transient faults, partially resulting from
insulator flashover from the high transient voltages induced by the lightning. Other
possible causes are swinging wires and temporary contact with foreign objects. The
majority of faults can be successfully cleared by the proper use of protective relays to
trip the respective circuit breakers and to bring back the system to normalcy using
high speed AR. This de-energizes the line long enough for the fault source to pass
and the fault arc to de-energize, then automatically recloses the line to restore
service. Thus, AR can significantly reduce the outage time due to faults and provide
a higher level of service continuity to the customer. Furthermore, successful high-
speed reclosing on transmission circuits can be a major factor when attempting to
maintain system stability during fault clearing.
Initial studies revealed that a detailed study of AR settings in the transmission
network of Ceylon Electricity Board(CEB) and their performance based on failure
analysis has not been carried out since the review of the protection system and
settings by Lahmeyer International in 1996. [4] Further there has been a brief
analysis by the PB power consultants in their report on the CEB transmission system
and organizational arrangements for operation and maintenance in October 1999. [5]
Since then there has been a comprehensive expansion of the CEB transmission
network. [6, 7]
Page 2 of 50
Initially the failure incidents of the Sri Lanka’s transmission network for the period
January 2006 to August 2012 were analyzed. Then the settings employed in high
speed AR schemes this network were studied and whether they are providing the
desired results are being discussed.
Main objective of the research is to propose suitable AR settings for the 132kV and
220kV lines in the Sri Lankan Transmission Network.
1.2 Identification of the problem
With the experience gained through failure analysis at the protection development
section of CEB for over four years period the need for a detailed study of AR settings
was felt. There has not been a comprehensive study, including stability analysis to
determine the AR schemes for the transmission network. There were some major
power system failures which could have been avoided if the AR schemes were
properly set. Further rapid development of the CEB power system and the
technological advancement of protection relays make some of existing settings
obsolete.
1.3 Objective of the study
The objective of the study is to determine suitable settings for AR for the Sri Lankan
transmission system after carrying out stability analysis using the existing CEB
power system which is modeled in PSSE software. By simulation of AR of some
selected lines, maximum time available for opening and reclosing the system without
loss of synchronism would be determined. Using analysis of previous failure
incidents and studying existing literature other factors that require proposing AR
settings would be determined.
This study will present a set of AR settings for both 220kV and 132kV systems
which will improve the AR success rate thereby improving the reliability of the
network. It will also minimize the risk of major failures resulted due to the definitive
tripping of important transmission lines due to transient faults.
Page 3 of 50
1.4 Importance of the study
A comprehensive study on the AR settings for the 132kV and 220kV lines in the Sri
Lankan Transmission Network has not been conducted in recent times. With the
rapid development of the transmission network there has been a need to revise the
existing settings to match with the current system. The outcome of this project will
help to improve the stability and reliability of the national grid.
1.5 Methodology
Existing settings were reviewed along with failure incidents recorded during the
period of November 2006 to August 2012 in the selected transmission lines. The
stability analysis was carried out with the existing settings and prospective settings
using the existing CEB power system which is modeled in PSSE software. Based on
the simulated results, analysis of failure incidents, review of existing settings and the
literature available on the practices followed in determining AR settings, a set of AR
settings for 220kV and 132kV transmission lines were proposed.
Page 4 of 50
Chapter 2
PRINCIPLES OF AUTO RECLOSING
2.1 Theory of Auto Reclosing
As discussed in the Chapter 1.1, the majority of faults in the transmission lines can be
successfully cleared by the proper use of protective relays to trip the respective
circuit breakers and to bring back the system to normalcy using high speed AR.
Power system stability is understood as the ability to regain an equilibrium state after
being subjected to a physical disturbance. [8] A primary concern in the application of
AR, especially on transmission lines is the maintenance of system stability and
synchronism. This is normally done through the application of high-speed tripping
and AR. The problems involved with maintaining system stability when AR during a
fault on the line depend on the characteristics of the system - whether it is loosely
connected, for example, with two power systems connected by a single tie line, or,
conversely, highly interconnected, in which case maintaining synchronism during
AR is much easier.
High-speed AR is used on transmission and subtransmission systems for improving
stability by clearance of transient faults. The intent of AR on transmission and
subtransmission systems, other than the maintenance of stability, is to bring back the
system to its normal configuration, with the minimum use of manpower whilst
limiting the outage time of the line to a minimum. System restoration becomes
increasingly important when applied to transmission lines that interconnect
generation systems and are critical for reliable power exchange between such
systems. Individual utility policy and system requirements dictate the complexity and
variety of automatic reclosing schemes in service today.[1]
Factors to consider when using high-speed AR include:[2]
Page 5 of 50
1 The maximum time available for opening and reclosing the system without loss
of synchronism (maximum dead time). This time is a function of the system
configuration and the transmitted power.
2 The time required for de-ionization of the arc path so that the arc will not restrike
when the breaker is reclosed. This time can be estimated by the use of a formula
developed from empirical data gathered from laboratory tests and field
experience.
3 The protection relay characteristics
4 The circuit breaker characteristics and limitations.
5 Choice of reclose reset time
6 Number of reclose attempts
The transient following the perturbation on the system is oscillatory and dampens to
a new quiescent condition if the system is stable. The oscillations are reflected as
power fluctuations over the power line and can be represented graphically using the
equal area criterion and the power-angle curve [9].
The power-angle curve of a synchronous machine relates the power output of the
machine to the angle of its rotor. For a two-machine system this can be represented
as:
Where:
P= the power transmitted between the machines during the transient condition
VS= the voltage at the sending end
VR= the voltage at the receiving end
δ= the angle by which VS leads VR
The maximum power occurs when the angle between the two machines is 90°s and
the minimum power occurs when the angle is 0° or 180°. Figure 2.1 shows a power-
angle curve for a simple two-machine system with a single transmission line
connecting the two sources, A and B. The curve for normal conditions is the one with
the greatest height and with a maximum of:
sinX
PRS
VV
Page 6 of 50
Figure 2.1 – Application of the Equal-Area Criterion for Stability to the Reclosing of
a Single-Circuit Tie between Systems A and B [3]
During the fault (2LG) the power-angle curve is reduced as shown, and during the
opening of the breakers, the amplitude of the curve is zero. The height of the
horizontal line labeled ‘Input’, Pi, represents the electrical and mechanical power
transmitted prior to the fault. The initial angular separation of machines A and B is
δ0, the clearing angle is δ 1, the reclosing angle is δ 2, and the angle of maximum
swing without loss of synchronism is δ 3. The equal area criterion requires that for
stability, area 2 must exceed area 1. Without reclosure, synchronism would be lost
regardless of the amount of power transmitted. Hence, the stability limit without
reclosure is zero. With rapid enough clearing and reclosure, however, the stability
limit can be made to approach the amplitude of the normal power-angle curve.
To determine whether the system in Figure 2.1 is stable, we must calculate the areas
1 and 2. If area 2 is greater than area 1, then the system is stable. If area 2 equals area
1, then the input power of 0.9 per unit, Pi, is the stability limit. Any higher input
power would cause area 2 to increase and area 1 to decrease, thus causing instability
(assuming they are equal prior to increasing the input power). If area 1 is greater than
pu 83.1
6.0
0.11.1P
BA
M
X
VV
Page 7 of 50
area 2, then the system is unstable. Area 2 is slightly less than area 1, thus the system
is unstable. In order to ensure stability for the 2LG fault, area 1 must be decreased
and/or area 2 must be increased. This can be done by reducing the input power, Pi, or
by clearing the fault faster (i.e., reclosing faster).
If single-phase AR is used on a transmission line, for example, a single-line to-
ground fault, tripping only the faulted phase will allow an interchange of
synchronizing power that would otherwise be unavailable when all three phases are
open. Hence by single-phase tripping/AR the stability limit of the line can be raised
above the limit obtainable with three-pole tripping and reclosing at the same speed.
Alternatively, the same stability limit can be achieved with slower AR.
Power angle curves give the power transfer as a function of phase angle difference
between sets of machines, and it is necessary to relate the phase angle difference to
time. This can be done by solving the swing equation for the particular sets of
machines.
The swing equation is
Pa = M d2δ/ dt2
where
Pa = accelerating power, difference between mechanical input and electrical output
M = Inertia constant
δ = displacement of machine rotor from a reference axis rotating at normal
synchronous speed
t = time
Solution of the swing equation gives phase angle δ as a function of time and can be
plotted against the swing curve. Using the swing curves for the particular machines,
and the power angle curves for the particular type of faults, it will be possible to
work out the maximum fault clearance time and auto-reclose dead time necessary to
maintain a given power transfer level.
Page 8 of 50
2.2 Basis for the analysis of Stability using software models
Using the swing curves for the particular machines, and the power angle curves for
the particular type of faults, it will be possible to work out the maximum fault
clearance time and auto-reclose dead time necessary to maintain a given power
transfer level.
If the system is stable, all interconnected synchronous machines should remain in
synchronism (i.e., operating in parallel and at the same speed) as shown in figure 2.2
(a). System shown in Figure 2.2 (b) is out of synchronism.
Figure 2.2 – Response of a four machine system during a transient [3]
2.3 PSSE Simulation Software & Network Model
PSCAD and PSSE are the power system simulation software that was considered to
carry out the above studies. The requirement was to model the actual existing
network of the CEB and simulate the selected scenarios. But the available license of
the PSCAD software was of limited capability which prevented the modeling of
complete transmission network. Then PSSE was considered which is a tool used by
the CEB.
PSS®E is an integrated, interactive program for simulating, analyzing, and
optimizing power system performance. It is capable of simulation of Power Flow,
Optimal Power Flow, Balanced or Unbalanced Fault Analysis, Dynamic Simulation,
Extended Term Dynamic Simulation, Open Access and Pricing, Transfer Limit
Analysis and Network Reduction. [10]
Page 9 of 50
Figure 2.3 – Snap shot of Biyagama – Kothmale transmission line modeled in
PSSE
Actual system of CEB which is modeled by the transmission planning branch and
system control centre was used to carryout the study. Complete diagram of the
network model used for the simulation of different auto reclosing scenarios is
presented in annexure D. Snap shot of the simulation is shown in the figure 2.3.
Page 10 of 50
Chapter 3
REVIEW OF EXISTING SETTINGS AND FAILURE ANALYSIS
3.1. Existing Auto Reclosing Settings of 220kV Lines
All the existing 220kV transmission lines in CEB network employ single phase and
three phase auto reclosing. Their settings are not uniform. Two most important lines
in the network has been selected for in-depth analysis of existing settings. They are
Biyagama – Kotmale line and Norochcholai – Veyangoda line. The existing settings
of all 220kV lines were studied.
Biyagama – Kothmale double circuit transmission line (70.5km) is the backbone in
CEB transmission network which connect Mahaweli power generation plants to the
load centre in Colombo. As discussed in chapter 2, the stability analysis of
transmission lines during AR comes in to picture when two networks independent
generation are connected through that line. e.g. Biyagama – Kothamale line where
Biyagama side is also connected to the thermal power complexes.
Veyangoda – Norochcholai double circuit transmission line (115 km) was selected
because of its critical importance during dry seasons when the Mahaweli generation
is low. Additionally these lines are frequently subjected to transient faults (Insulator
flashovers) due to the high salinity of the coastal environment. But it is observed that
the line is definitively tripped even for transient faults and resultant effect of one of
these incidents have lead to scheduled load shedding in August 2012.
3.1.1. Summary of existing settings
Settings of 220kV transmission lines have been determined during the
commissioning period of each transmission line and are sometimes being altered
after failure analysis. Table 3.1 presents a summary of existing settings of Biyagama
– Kotmale and Norochcholai – Veyangoda transmission lines.
Page 11 of 50
Table 3.1 – Existing 220kV AR settings
No Substation & Line
Portion
Single phase Auto reclosing 3 phase Auto Reclosing
Syn. check
condition for AR
Dead
Time
Syn. check
condition for AR
Dead
Time
1 Norochchole GIS –
Veyangoda Line 1 & 2
No Synchro.
Check 800 ms LB/LL 750 ms
2 Veyangoda GSS –
Norochchole Line 1 & 2
No Synchro.
Check 800 ms LB/LL or LB/DL 550 ms
3 Biyagama – Kothmale
Line
No Synchro.
Check 450ms LB/DL 1.0S
4 Kothmale - Biyagama
Line
No Synchro.
Check 450ms LB/LL or LB/DL 1.2S
3.1.1.1.Single and three phase AR
Statistics show that above 80% of faults on overhead lines are transient, with more
than 90% of these are single phase to earth faults. The most common causes of
transient faults are over voltages induced by lightning, which result in flashover of
insulator. Other possible causes are swinging wires and temporary contact with
foreign objects. For such faults, single pole AR provides a means of improving
transient stability and reliability. Furthermore, in single phase AR only the faulted
phase is tripped and 58% of transmission capacity is still retained via the two healthy
phases [11].
Single phase AR is employed in 220 kV lines only. They are not used in 132 kV
lines. Single phase auto reclosing is used without synchronization. Hence lower dead
times are employed in comparison to three phase AR.[6]
The stability limit of the line can be raised above the limit obtainable with three-pole
tripping and reclosing at the same speed. Alternatively, the same stability limit can be
achieved with slower AR. Single pole switching also has the advantage of reducing
mechanical shock to generators compared to three phase reclosing. [4]
Page 12 of 50
Three phase AR is used in all transformers and medium voltage feeders. i.e. 33 kV
3.1.1.2.Dead Times
Dead time is the time between opening of the CB due to a fault and the first AR
attempt. It is common practice to employ a dead time based on the time needed for
the transient fault to extinguish and to sustain system stability and reliability.
However employing a fixed prescribed dead time can pose problems. In the case of
an arcing fault, for example, a fault restrike due to insufficient time for the fault path
to fully de-ionise can threaten system stability and reliability. On the other hand,
unsuccessful reclosing during a permanent fault may aggravate the potential damage
to the system and equipment [12]. For some EHV lines, especially near generating
plants, the classical automatic reclosing of breakers cannot be used and therefore
adaptive reclosing schemes have been introduced over the past decades [13,14,15].
3.1.1.3.Synchro Check Conditions
Re-closing of the breaker is only done when the two sides are in Synchronism, when
both sides are in live condition. Synchronism check relays generally check for phase
angle, voltage and frequency difference when employed in AR schemes. Table 3.2
gives existing synchro check conditions in CEB network.
Table 3.2 – Synchro check conditions
Acceptable voltage difference ∆V = +_ 10%
Acceptable phase angle difference ∆d = +_ 20 Deg
Acceptable frequency difference ∆f = +_0.1 Hz
Live Bus LB 80 % Ub (Ub – Base Voltage)
Live Line LL 80 % Ub
Dead Bus DB 30 % Ub
Dead Line DL 30 % Ub
Page 13 of 50
3.1.1.4.Single Shot and Multi Shot AR
Only single shot AR is used in transmission lines (220 kV/ 132 kV) to avoid any
damage to equipment due to persistent faults. Further most transient faults are cleared
within the first AR cycle making multi shot AR less beneficial.
3.1.2. Analysis of previous failure incidents of 220kV system
Success rate or suitability of existing AR settings can be determined by analyzing
previous failure incidents. All incidents involving 220kV transmission lines for the
past 5 years have been studied. Detailed analysis was carried out on few incidents
involving two critical lines in the network, which are Biyagama –Kothmale and
Norochcholai – Veyangoda lines.
3.1.2.1.Failure incidents of Biyagama –Kothmale 220kV transmission lines
Biyagama - Kothmale 220kV transmission line is the backbone connecting Mahaweli
complex to the load centre in Colombo. Hence the tripping of these lines could lead
to a major failure in CEB transmission network. When analyzing previous records of
such incidents it was evident that proper auto reclosing of the line could have
prevented some total failures of the national grid.
When investigating the incidents recorded from 2006-2012, it is revealed that most of
the failures has resulted in definitive trips when the dead time was 5 seconds. AR
success rate has improved after the revision of dead time to 1.2s in 2009.
Please refer Appendix A for a detailed list of failure incidents involving Biyagama –
Kothmale Transmission lines.
There were incidents involving these lines that lead to blackouts / Major failures
which could have been prevented if AR settings had been properly set:
A. Total System Failure on 15th November 2006 at 19.33 hrs.
B. Major System Failure on 28th April 2008 at 17.28 hrs.
Page 14 of 50
Detailed analysis Major System Failure on 28th April 2008 at 17.28 hrs.
On 28th April 2008 at 17.28 hrs there was a double circuit fault in Kotmale -
Biyagama 220 kV lines and the system lost most of the Mahawali hydro generators
due to tripping of these lines. This has resulted in a major failure in the system. On
this instance Kothmale- New Anuradapura 220 kV line was switched off for
maintenance work. Prior to tripping of Kothmale - Biyagama lines the load on these
lines was approximately 900 A (300 MW) and the total system generation was 1108
MW.
The failure has been initiated by double circuit fault in Biyagama – Kothmale 220 kV
lines involving Yellow - Blue phases and ground. The distance relays installed in
both ends have seen a zone 1 multi-phase fault and tripped respective circuit breakers
and initiated the auto-reclosers. After the auto-recloser dead time (5 sec) Biyagama
end breakers have been re-closed successfully but breakers at Kothmale end have
been failed to re-close. At t = 5 sec Biyagama end frequency has fallen to 47.4 Hz
and hence the check synchronizing relays at Kothmale end had blocked auto-
reclosing.
Then the power flown from Kothmale to Biyagama has been re-routed to the system
via Rantambe 220kV/132kV system transformer. The tripping of Kothmale-
Biyagama lines has caused a power swing through Badulla-Laxapana lines.
Apparently due to this the distance relays installed at Badulla – Laxapana lines have
tripped the line by operation of distance protection zone 1. (At t =0.6 sec.) By this
time the system has been divided into two sections viz. Mahawali power stations
with Badulla and Ampara GSS have been in one system and rest of the grid
substations as another system.
At t = 0.6 sec. the main system was having a power deficiency of about 270 MW and
the system frequency started decreasing. Please see figure 3.2 for frequency vs. time
curve. According to the frequency plot, the system frequency has started to increase
at about t = 4.1 sec due to automatic load shedding and governor action of individual
machines. But the recovery has not been fast enough to avoid tripping of thermal
machines. Viz. Kelanithissa Barge, KCCP ST and GT.
Page 15 of 50
At t = 5.15 sec Kelanithissa Barge mounted power plant (60 MW) and at t = 5.5 sec
Kelanithissa combine cycle steam power plant (57 MW) tripped on under frequency.
Further at t = 6.5 sec Kelanithissa combine cycle gas turbine tripped (104 MW) and
started collapsing the system frequency.
Under Frequency Trip Settings:-
Kelanithissa Barge power plant : 47.5 Hz, 0.0 sec.
Kelanithissa combine cycle steam power plant : 48.0 Hz, 3.0 sec.
Kelanithissa combine cycle gas turbine power plant : 47.5 Hz, 3.2 sec.
Figure 3.1 - Digital Disturbance record of Kelanitissa GIS
Kothmale, Victoria, Randenigala, Rantambe power stations and Badulla, Ampara
GSS were in this system. Initially this system had excess power of about 300 MW.
Later this system got stabilized and fed the loads at Rantambe, Badulla and Ampara
GSS.
Page 16 of 50
43
44
45
46
47
48
49
50
51
-0.5 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5
Time (s)
Fre
q (
Hz)
60
80
100
120
140
160
180
200
220
240
Vo
ltag
e (k
V)
Freq
Volt
Tripping of Badulla-Laxapana lines (300 MW)
Tripping of Biyagama-Kothmale lines
Tripping of KCCP-GT (104 MW)
Tripping of KCCP-ST (57 MW)
Tripping of Kelanithissa Barge
(60 MW)
43
44
45
46
47
48
49
50
51
-0.5 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5
Time (s)
Fre
q (
Hz)
60
80
100
120
140
160
180
200
220
240
Vo
ltag
e (k
V)
Freq
Volt
Tripping of Badulla-Laxapana lines (300 MW)
Tripping of Biyagama-Kothmale lines
Tripping of KCCP-GT (104 MW)
Tripping of KCCP-ST (57 MW)
Tripping of Kelanithissa Barge
(60 MW)
The existing auto-reclosing scheme in Biyagama – Kothmale lines were having dead
time of 5 seconds. The need was felt to review the dead time and if possible to reduce
the same.
The results of these incidents clearly demonstrate the significance of implementing
suitable AR settings to improve power system reliability. Consequent to this incident
the AR settings were revised to the values shown in Table 3.1.
Figure 3.2 - Frequency Plot for the major failure on 28th April 2008 at 17.28 hrs
3.1.2.2.Failure incidents of Veyangoda – Norochcholai 220kV transmission lines
Veyangoda – Norochcholai double circuit 115km transmission line was
commissioned in 2011 to connect Lakvijaya coal power plant to the national grid.
Since then there have been several failure incidents involving the line. Availability of
Page 17 of 50
these two lines is critical to match the demand especially during the drought season
where hydropower generation is at minimum level.
When investigating the incidents recorded since 2011 it is apparent that most of the
times AR has been successful at Veyangoda end. But since the AR switch is in off
position at Norochcholai end definitive trip of the line has resulted in each incident
recorded.
Please refer Appendix B for the detailed list of failure incidents involving Veyangoda
– Norochcholai Transmission lines.
AR switch was at off position at Norochcholai end and hence the line has tripped
definitively even for transient faults which have lead to serious crisis situations in the
national grid as discussed below.
One of the most significant incidents was the tripping of the Lakvijaya power plant
as a result of a flashover in the transmission line and subsequent events that lead to
scheduled power cuts in the island.
Tripping on 08 August 2012 5.57 am
On 08 August 2012 5.57 am, Unit at the Lakvijaya power plant tripped after a total
disconnection from the grid due to one 220k V line circuit taken out for maintenance
and the other one lost due to flash over. During the turbine-generator rundown
bearings hindered damage as was verified during an unsuccessful restart attempt on
12 August-9pm. As a result the bearings 3&4 needed replacement after a cool-down
period of the turbine of nine days. On 26 August, 10.30pm the Unit was back on the
grid on low load. However two unresolved problems hindered the further loading of
the Unit namely undue noise emitted from the main transformer and debris fliers in
the main cooling water lines to the condenser out of order.
On 07 June 2011 a very similar incident took place with most conditions leading up
to the Unit trip (2 line circuits lost, generator breaker remained closed) and the
outcome (failure to runback to house load, EDG failed to supply power .lube oil
starvation, turbine bearing damage. etc) being almost identical.
Page 18 of 50
Failures contributing to the Incident
The generator over-frequency protection is set to operate at 52.5 HZ 0.5s and trips
the turbine (but not the generator circuit breaker) Concerns about this setting had
been highlighted during reviews of the settings prior to commissioning and again
following the incident in June 2011. The action of this protection has the adverse
consequences.
I. There is no chance of a trip to Island or House mode since the turbine is
tripped.
II. Without tripping the generator circuit breaker, the turbine governor system
operation by first stage of OPC governing at 51.5 Hz ( when the steam values
are shut.) occurs later than would be the case for a load rejection type
situation. The resulting over speed peak was 4.1 Hz. close to the second stage
of governor protection over speed trip at 55 Hz. It is possible that this
additional speed rise could have contributed to damage to an already
imperfect bearing (following damage in June 2011)
III. The generator remained connected to the system for min 48s. During this
period the voltage and frequency steadily declined until the generator CBX
190 was tripped by the excitation protection. Any attempt to close by DAR or
manually during this period would have been disastrous – hence the
recommendation last year to leave DAR switched off until the matter is
resolved.
IV. The declining frequency on the auxiliary system is matched by an over-
fluxing control within the excitation system so that voltage is reduced in
proportion to frequency. Operation of pumps and fans etc. will be impaired
until such time as the EDG starts to supply only essential drives.
Following immediately on from the incident, the overhead line did not auto-reclose
and attempts by the operators to switch back the affected line and later the line under
maintenance were unsuccessful until supply was restored through the Veyangoda 2
line almost 1 hour after the Veyangoda 1 line had tripped.
Page 19 of 50
The auto-reclose system is switched out at Puttalam. This has been deliberate
pending resolution of issues arising from the incident of June 2011. The line auto-
reclosed from the Veyangoda end and manual operation would be needed to switch
in the Puttalam end.
Figure 3.3 - Digital Disturbance Record for Veyangoda – Norochcholai line 1
The fault was multi-phase type so that irrespective of whether the auto-reclose had
been switched in, in this case it would have been unsuccessful due to loss of
synchronism between the generator (if it had kept running) and the system.
3.2. Existing Auto Reclosing Settings of 132kV Lines
With the growth of the 220kV transmission network of CEB, effects of AR of
individual 132kV transmission lines on the overall stability of the network is largely
insignificant. But with proper AR of 132kV lines the reliability of the transmission
network can be improved and automatic load shedding can be minimized. Hence it is
possible to employ relatively longer dead times for AR of 132kV transmission lines.
Page 20 of 50
Figure 3.4 - Digital Disturbance Record for Norochcholai - Veyangoda line 1
3.2.1. Review of settings of 132kV system 1
AR scheme that involve Athurugiriya and Thulhiriya lines were observed to have a
very high AR success rate. Hence the scheme with synchrocheck conditions are
presented in figure 3.5.
Page 21 of 50
Figure 3.5 – Autoreclose scheme of 132kV network 1
Table 3.3 – AR settings of Kolonnawa – Athurugiriya & Polpitiya - Seethawaka lines
No Substation & Line
Portion
Syn. check
condition for AR
Dead
Time
Reclaim
Time/Inhibit
Time
1 Kolonnawa - Athurugiriya
Lines
LB/LL or LB/DL 0.8 Sec 180 Sec
2 Athurugiriya – Kolonnawa
Lines LB/LL 1.1 Sec 180 Sec
3 Polpitiya - Seethawaka
Lines
LB/DL 0.8 Sec 180 Sec
4 Seethawaka – Polpitiya
Lines LB/LL 1.1 Sec 180 Sec
Page 22 of 50
3.2.2. Review of settings of 132kV system 2
AR settings of Pannipitiya- Panadura – Horana 132kV system is quite similar to
that of system 1.
Figure 3.6 – Autoreclose scheme of 132kV network 2
Table 3.4 – AR settings of Pannipitiya- Panadura – Horana 132kV system
No Substation & Line
Portion
Syn. check
condition for AR
Dead
Time
Reclaim
Time/Inhibit Time
1 Pannipitiya- Matugama
Line
LB/DL 800 ms 300 Sec
2 Matugama- Pannipitiya
Line
LB/LL 1.1 Sec 300 Sec
3 Panadura- Pannipitiya
Matugama Line
DB/LL 1.5 Sec 300 Sec
Some lines like Pannala-Katunayake, Aniyakanda- Kelaniya has AR dead times
as low as 300ms.
Page 23 of 50
3.2.3. Analysis of previous failure incidents of 132kV system
Figure 3.7 Unsuccessful AR incident in Polpitiya Seethawaka line
Digital Disturbance records obtained from the BEN 5000 DDR installed at Polpitiya
Powerstation were quite helpful in assessing the suitability of the existing settings
(Table 3.5) implemented at Polpitiya Seethawska lines. Figure 3.7 shows an incident
involving a permanent fault while figure 3.8 provide a clear testimony to the
successful AR for a disturbance due to a transient fault.
Figure 3.8 Successful AR incident in Polpitiya Seethawaka line
Page 24 of 50
Chapter 4
STABILITY ANALYSIS
4.1. Three phase Autoreclose of 220kV lines
4.1.1. Biyagama – Kothmale 220kV lines
It is understood that the most critical line that affect system stability are Biyagama –
Kothmale 220kV double circuit transmission line. So the autoreclose of these lines
was simulated using PSSE under several power system conditions. Most critical of
these is when hydro generation of the Mahaweli complex is at the maximum which is
connected to the main load centre in Colombo. Thermal maximum condition was
also considered.
The simulated dead times were 5s, 1.2s, 1s, 750ms, 500ms and 300ms. 300ms is the
lowest possible time that can be assigned considering the fault clearance times. 5s
was the setting used before 2008. 1.2s is the currently applied 3ph AR time setting.
Apart from these values 500ms, 750ms and 1000ms were considered to obtain a
better understanding of the response of the power system to auto reclosing at
different dead times.
4.1.1.1. Simulation of AR for a 3ph double circuit fault at Biyagama – Kothmale
line with a dead time of 5s
Dead time of 5 seconds was the setting that was available during the two total
failures mentioned above and it was subsequently changed in 2008.
Algorithm adopted for simulation of 3ph double circuit fault:
1. Run the instance of the model for 2 seconds.
(Mahaweli generation 166MW, Thermal 718MW)
2. Create 3ph double circuit fault & run for 50ms
3. Trip both lines
Page 25 of 50
4. Clear the fault
5. Run the instance of the model for 5 seconds. (Dead time=5s)
6. Reclose the line
7. Run the model for another 15 seconds
The outputs of these simulations can be obtained in several graphs. Figure 4.1 shows
the graph between relative power angles versus time. As we discussed above for the
stability to be maintained relative angles of these lines should be in parallel. When a
dead time of 5s is selected the system stability is disturbed. Rotor angles of Victoria
and Kothmale machines are in parallel while the Kelanithissa CCP and Puttalama
Coal plant are separated. Hence the stability of the system cannot be maintained with
a dead time of 5s.
Figure 4.1 - Relative rotor angle vs Time for a dead time of 5s
Power angle curve of the Kothmale machine at this instance is shown in figure 4.2.
Reference: Rotor angle of generator at Kothmale PS
Victoria
Kelanithissa Combined Cycle
Puttalama Coal
Angle Difference
Page 26 of 50
Figure 4.2 - Power Angle Curve for Kothmale Generator
4.1.1.2.Simulation of 3ph double circuit fault at Biyagama – Kothmale line with
a dead time of 1.2s
Dead Time of 1.2s is the setting that is currently used for three phase auto reclosing
in these lines. It was simulated following the steps similar to that were followed in
previous cases.
Algorithm adopted for simulation of 3ph double circuit fault:
1. Run the instance of the model for 2 seconds.
(Mahaweli generation 166MW, Thermal 718MW)
2. Create 3ph double circuit fault & run for 50ms
3. Trip both lines
4. Clear the fault
5. Run the instance of the model for 1200 miliseconds. (Dead
time=1200ms)
6. Reclose the line
7. Run the model for another 15 seconds
Rotor Angle
Power Generated
Page 27 of 50
Simulation result for AR with a dead time of 1.2s in Biyagama Kothamle 220kV line
for a three phase double circuit fault is shown in figure 4.3.
Figure 4.3 - Relative rotor angle vs Time for a dead time of 1.2s
4.1.1.3.Simulation of 3ph double circuit fault at Biyagama – Kothmale line with
a dead time of 1s
Simulation for dead time of 1s was carried out using the same algorithm that was
described under 4.1.1.1 The output plot was obtained as a plot of Rotor angle
realative to that of Kothmale against time.
Algorithm adopted for simulation of 3ph double circuit fault:
1. Run the instance of the model for 2 seconds.
(Mahaweli generation 166MW, Thermal 718MW)
2. Create 3ph double circuit fault & run for 50ms
3. Trip both lines
4. Clear the fault
5. Run the instance of the model for 1 second. (Dead time= 1 s)
6. Reclose the line
Reference: Rotor angle of generator at Kothmale PS
Victoria
Page 28 of 50
7. Run the model for another 15 seconds
Simulation result for AR with a dead time of 1s in Biyagama Kothamle 220kV line
for a three phase double circuit fault is shown in figure 4.4.
Figure 4.4 - Relative rotor angle vs Time for a dead time of 1s
4.1.1.4.Simulation of 3ph double circuit fault at Biyagama – Kothmale line with
a dead time of 750ms
Simulation for dead time of 750ms was carried out using the same algorithm that was
described under 4.1.1.1 The output plot was obtained as a plot of Rotor angle relative
to that of Kothmale against time.
Algorithm adopted for simulation of 3ph double circuit fault:
1. Run the instance of the model for 2 seconds.
(Mahaweli generation 166MW, Thermal 718MW)
2. Create 3ph double circuit fault & run for 50ms
3. Trip both lines
4. Clear the fault
Reference: Rotor angle of generator at Kothmale PS
New Laxapana PS
Kelanithissa Combined Cycle
West Coast Power Plant
Lakvijaya Coal Power Plant
Angle Difference
Page 29 of 50
5. Run the instance of the model for 0.75 second. (Dead time= 0.75 s)
6. Reclose the line
7. Run the model for another 15 seconds
Simulation result for AR with a dead time of 0.75s in Biyagama Kothamle 220kV
line for a three phase double circuit fault is shown in figure 4.5.
Figure 4.5 - Relative rotor angle vs Time for a dead time of 750ms
4.1.1.5.Simulation of 3ph double circuit fault at Biyagama – Kothmale line with
a dead time of 500ms
Simulation for dead time of 500ms was carried out using the same algorithm that was
described under 4.1.1.1 The output plot was obtained as a plot of Rotor angle
realative to that of Kothmale against time.
Algorithm adopted for simulation of 3ph double circuit fault:
1. Run the instance of the model for 2 seconds.
(Mahaweli generation 166MW, Thermal 718MW)
2. Create 3ph double circuit fault & run for 50ms
3. Trip both lines
4. Clear the fault
Reference: Rotor angle of generator at Kothmale PS
New Laxapana PS
Kelanithissa Combined Cycle
West Coast Power Plant
Lakvijaya Coal Power Plant
Page 30 of 50
5. Run the instance of the model for 500 milliseconds. (Dead time= 500 ms)
6. Reclose the line
7. Run the model for another 15 seconds
Simulation result for AR with a dead time of 0.5s in Biyagama Kothamle 220kV line
for a three phase double circuit fault is shown in figure 4.4.
Figure 4.6 - Relative rotor angle vs Time for a dead time of 500ms
4.1.1.6.Simulation of 3ph double circuit fault at Biyagama – Kothmale line with
a dead time of 300ms
Dead Time of 300ms is the minimum setting that could be set after considering fault
clearance times and breaker operation times.
Algorithm adopted for simulation of 3ph double circuit fault:
1. Run the instance of the model for 2 seconds.
(Mahaweli generation 166MW, Thermal 718MW)
2. Create 3ph double circuit fault & run for 50ms
3. Trip both lines
4. Clear the fault
5. Run the instance of the model for 300 miliseconds. (Dead time=300ms)
Reference: Rotor angle of generator at Kothmale PS
New Laxapana PS
Kelanithissa Combined Cycle
West Coast Power Plant
Lakvijaya Coal Power Plant
Page 31 of 50
6. Reclose the line
7. Run the model for another 15 seconds
Simulation result for AR with a dead time of 300ms in Biyagama Kothamle 220kV
line for a three phase double circuit fault is shown in figure 4.7.
Figure 4.7 - Relative rotor angle vs Time for a dead time of 300ms
When a 300ms of dead time is selected the system disturbance is cleared within a
short period. Plot in figure 4.7 shows that they are in parallel and in synchronism.
4.1.2. Veyangoda – Norochcholai 220kV lines
4.1.2.1. Simulation of 3ph double circuit fault at Veyangoda – Norochcholai line
with a dead time of 750ms
Dead Time of 750ms is the setting that is currently used for three phase auto
reclosing in these lines.
Algorithm adopted for simulation of 3ph double circuit fault:
1. Run the instance of the model for 2 seconds.
Angle Difference
Puttalama Coal
Reference: Rotor angle of generator at Kothmale PS
Victoria
Kelanithissa Combined Cycle
Page 32 of 50
(Mahaweli generation 166MW, Thermal 718MW)
2. Create 3ph double circuit fault & run for 50ms
3. Trip both lines
4. Clear the fault
5. Run the instance of the model for 750 miliseconds. (Dead time=750ms)
6. Reclose the line
7. Run the model for another 15 seconds
Simulation result for AR with a dead time of 750ms in Veyangoda Norochcholai
220kV line for a three phase double circuit fault is shown in figure 4.8 and figure
4.9.
Figure 4.8 – Rotor angle vs Time for a dead time of 750ms
As shown in figure 4.8 rotor angle of Puttalama PS and Victoria PS are not in
parallel indicating that they are not in synchronism.
Victoria
Puttalama Coal
Angle
Page 33 of 50
Figure 4.9 – Relative Rotor angle vs Time for a dead time of 750ms
4.2. Single phase Autoreclose of 220kV lines
Single phase AR is used when the faults involve only one phase of the transmission
line i.e.L-G faults. This will help to clear the fault with minimum disturbance to the
system. Automatic reclosing of the breaker is done without synchronizing the two
ends. Only 220kV breakers are capable of single pole tripping in our network. Hence
single phase auto reclosing is used only for 220kV transmission lines.
4.2.1. Biyagama – Kothmale 220kV lines
4.2.1.1. Single phase AR of Biyagama - Kothmale with a dead time of 450 ms
The existing dead time setting for single phase AR in Biyagama Kothmale line is
450ms.
Algorithm adopted for simulation of single phase to ground fault:
Puttalama Coal
Reference: Rotor angle of generator at Kothmale PS
Page 34 of 50
1. Run the instance of the model for 2 seconds. Consider one circuit of
double circuit lines are out for maintenance.
(Mahaweli generation 166MW, Thermal 718MW)
2. Create single phase fault & run for 50ms
3. Trip the single phase involved.
4. Clear the fault
5. Run the instance of the model for 450 miliseconds. (Dead
time=450ms)
6. Reclose the line
7. Run the model for another 15 seconds
The results are shown in figure 4.10 and figure 4.11.
Figure 4.10– Rotor angle vs Time for a dead time of 450ms
Puttalama Coal
Victoria
Kothmale
Page 35 of 50
Figure 4.11 - Relative Rotor angle vs Time for a dead time of 450ms
Both 450ms & 750ms can be increased without compromising stability and
reliability. It is advisable to have longer dead times near generating stations to
limit thermal/ mechanical stresses on the generators.
4.2.2. Veyangoda – Norochcholai 220kV lines
4.2.2.1. Single phase AR of Veyangoda Norochchole with a dead time of 800 ms
Single phase auto reclosing at Veyangoda Norochcholai lines is quite important
since they are subject to transient L-G faults due to the saline environment in the
transmission line route. Effects of single phase AR were simulated to compare
the output with the three phase AR results. Simulation steps were similar to that
was followed in single phase AR of Biyagama – Kothmale lines. Simulation
resultas are shown in figure 4.12.
Puttalama Coal
Reference: Rotor angle of generator at Kothmale PS
Page 36 of 50
Figure 4.12 - Relative Rotor angle vs Time for a dead time of 800ms
4.3. Autoreclose of 132kV lines
Single shot three phase auto reclosing is used in almost all the 132kV
transmission lines in the CEB network. For the simulation of stability two lines
New Laxapana – Balangoda and Pannipitiya – Mathugama which were identified
to have been associated with several failure incidents in the past few years have
been selected.
4.3.1. 132kV three phase AR Balangoda – New Laxapana with dead time of
300ms
The existing dead time setting for three phase AR in New Laxapana – Balangoda
line is 300ms. Hence dead time of 300ms, 500ms and 1200ms were simulated.
Algorithm adopted for simulation of three phase double circuit fault:
1. Run the instance of the model for 2 seconds. (Mahaweli
generation 166MW, Thermal 718MW)
2. Create 3ph double circuit fault & run for 50ms
Puttalama Coal
Reference: Rotor angle of generator at Kothmale PS
Page 37 of 50
3. Trip both lines
4. Clear the fault
5. Run the instance of the model for 300 miliseconds. (Dead
time=300ms)
6. Reclose the line
7. Run the model for another 15 seconds
Figure 4.13 - Relative Rotor angle vs Time for a dead time of 300ms
Simulation result for AR with a dead time of 300ms in New Laxapana – Balangoda
132kV line for a three phase double circuit fault is shown in figure 4.13.
4.3.2. 132kV three phase AR Balangoda – New Laxapana with dead time of
500ms
The minimum dead time for 132kV transmission lines is 286.5 ms. This is further
explained in chapter 5.2. To allow more time for fault clearance a dead time of
500ms can be set and same has been simulated following similar algorithm to that of
4.3.1 changing only the dead time. Resulting plot of relative rotor angle vs time is
shown in Figure 4.14
Samanalaweva
Reference: Rotor angle of generator at New Laxapana
ACE Embilipitiya
KCCP
Page 38 of 50
Figure 4.14 - Relative Rotor angle vs Time for a dead time of 500ms
Simulation result for AR with a dead time of 500ms in New Laxapana – Balangoda
132kV line for a three phase double circuit fault is shown in figure 4.14.
4.3.3. 132kV three phase AR Balangoda – New Laxapana with dead time of
1200ms
For highly interconnected transmission lines longer dead times can be set. It was
interesting to simulate for a longer dead time for Balangoda - New Laxapana lines
although these lines connect two islands. Hence a dead time of 1200ms was
simulated following similar algorithm to that of 4.3.1 changing only the dead time.
Resulting plot of relative rotor angle vs time is shown in Figure 4.15
Samanalaweva
Reference: Rotor angle of generator at New Laxapana
ACE Embilipitiya
KCCP
Page 39 of 50
Figure 4.15- Relative Rotor angle vs Time for a dead time of 1.2s
4.3.4. 132kV three phase AR Pannipitiya – Mathugama with a dead time of
800ms
The existing dead time setting for three phase AR in Pannipitiya Mathugama line is
800ms.
Algorithm adopted for simulation of three phase double circuit fault:
1. Run the instance of the model for 2 seconds. (Mahaweli
generation 166MW, Thermal 718MW)
2. Create 3ph double circuit fault & run for 50ms
3. Trip both lines
4. Clear the fault
5. Run the instance of the model for 800 miliseconds. (Dead
time=800ms)
6. Reclose the line
7. Run the model for another 15 seconds
Samanalaweva
Reference: Rotor angle of generator at New Laxapana
ACE Embilipitiya
KCCP
Page 40 of 50
Figure 4.16- Relative Rotor angle vs Time for a dead time of 800ms
Simulation result for AR with existing dead time of 800ms in Pannipitiya
Mathugama 132kV line for a three phase double circuit fault is shown in figure 4.16.
4.4. Effects of Autoreclose on generators
4.4.1. Three phase autoreclose
Figure 4.17 – Power angle curve of Victoria Generators for 3ph AR of Biyagama
Kothmale lines dead time 1.2s
Mechanical Power (pu)
Rotor angle
Page 41 of 50
As shown in figure 4.17 the power angle curve of Victoria generators for AR of
Biyagama Kothmale lines with a dead time of 1.2s, the curve returns to its original
position indicating that the stability of the generators are maintained under these
conditions.
4.4.2. Single phase autoreclose
Figure 4.18 – Power angle curve of Victoria Generators for 1ph AR of Biyagama
Kothmale lines dead time 450ms
Figure 4.18 shows the power angle curve of Victoria generators for single AR of
Biyagama Kothmale lines with a dead time of 450ms, the curve returns to its original
position indicating that the stability of the generators are maintained under these
conditions
13
Power Angle Curve Victoria GeneratorMechanical Power (pu)
Rotor angle
Page 42 of 50
Chapter 5
RESULTS AND ANALYSIS
5.1. AR of 220kV Transmission Lines
Analysis of existing settings, failure incidents and PSSE simulation results provide
the basis for determining the most suitable settings for the auto reclosing settings of
CEB’s transmission network.
The failure analysis using digital disturbance records reveal that most of the transient
faults are cleared within 100ms. The breaker operation times and relay operation
times also need to be considered.
As per Protective Relaying Theory & Application by ABB Minimum Dead Time T is
given by:
T = 10.5 + kV / 34.5 cycles
Hence for 220kV transmission lines the minimum dead time shall be:
T= 10.5 + 220/34.5 = 16.87 cycles = 337.5 ms
Table 5.1 – Proposed AR settings for Biyagama – Kothmale and Veyangoda –
Norochcholai 220kV lines
No Substation & Line
Portion
Single phase Auto reclosing 3 phase Auto Reclosing
Syn. check
condition for AR
Dead
Time
Syn. check
condition for AR
Dead
Time
1 Norochchole GIS –
Veyangoda Line 1 & 2
No Synchro.
check 450 ms LB/LL 750 ms
2 Veyangoda GSS –
Norochchole Line 1 & 2
No Synchro.
Check 450 ms LB/LL or LB/DL 550 ms
3 Biyagama – Kothmale
Line
No Synchro.
check 450 ms LB/LL 750 ms
4 Kothmale - Biyagama
Line
No Synchro.
check 450 ms LB/LL or LB/DL 550 ms
Page 43 of 50
According to the PSSE simulations it is advisable to use a dead time as small as
possible for the Biyagama – Kothmale lines since it directly affects the overall
system stability of CEB transmission network. But it should be at least 337.5 ms on
technical basis. Considering the old condition of available switchgear, an additional
tolerance for the initial tripping of the breaker should be allowed. Hence it is safe to
apply 550ms for the A/R dead time for the first reclosing end for multi phase faults.
For the other end it is safe to apply 200ms delay to allow the energization of the line.
Synchrocheck condition shall be LB/LL or LB/DL for the end which will first reclose
while the other end should be closed after checking for the LB/LL condition only.
For single phase AR it is recommended to provide a dead time of 450ms based on
existing disturbance records and available literature. This is much safer than three
phase AR and has no effect on system stability as per the PSSE simulations. Here the
automatic reclosing of the breaker will be performed without synchrocheck.
5.2. AR of 132kV Transmission Lines
Auto reclosing of 132kV lines has a limited effect on the overall system stability.
Hence it is possible to employ longer dead times to enable higher AR success rate.
Analysis of existing settings reveal that there a uniform standard has not been
followed in determining the AR settings of 132kV lines. Some lines like Pannala-
Katunayake, Aniyakanda- Kelaniya has AR dead times as low as 300ms.
But as for the equation 5.1 the minimum dead time for 132kV transmission lines
shall be:
T= 10.5 + 132/34.5 = 14.32 cycles = 286.5 ms
Considering the time delays involved in the initial tripping operation much longer
dead time shall be adopted for AR of 132kV lines.
After considering all these factors including the analysis of past incidents and AR
success rates it is recommended to implement AR settings that are available in
Pannipitiya- Panadura – Horana lines (Table 3.6) as a standard throughout the
network.
Page 44 of 50
Analysis of existing schemes revealed that relays capable of AR are not available in
some old transmission lines. (Refer Annexure 3) Hence it is recommended to install
AR schemes for these lines to improve reliability. AR of Balangoda – New laxapana
lines would have prevented three major failures which affected the southern region in
this year alone.
5.3. AR of Generator feeders
On single-tie circuits with dispersed generation, reclosing on the circuit must be
delayed long enough for the dispersed generation to be isolated from the utility. [16,
17] If this does not happen, the generator may be damaged due to the utility source
closing into the generator out of synchronism. As an additional safety factor, where
there is customer generation, voltage supervision is often applied to the AR scheme.
In this case, AR is delayed until a dead line is sensed (also known as live line
blocking, or LLB), thus preventing reclosing into the dispersed generation.
Alternatively, if high-speed tripping (transfer trip, pilot wire, etc.) is used to trip the
generation, high-speed reclosing may be considered. If the dispersed generator has
the capacity to maintain the connected load, it may be used to do so in the event that
the utility tie is lost. In this case, the dispersed generation needs to have the ability
for dead line closing. In addition, before the utility tie is reestablished, this generation
must be isolated from the utility to prevent the utility from damaging the generator
when re-energizing. This can be done either locally or remotely. The generation can
also be tied back to the utility system using synchronism check. If the generation
capacity is insufficient to supply the connected load, it should be removed from the
system upon a trip of the utility supply and prior to the utility reclosing.
Effects of AR on Generator Shafts
Recent studies have raised concerns with reclosing breakers near generation and the
possibility of exceeding stress limits in turbine generator shafts. As early as 1944, in
a paper on single pole switching, the problem of mechanical shock to generator
shafts during fault clearing and reclosing was discussed. The authors concluded that
the calculation of stresses “may dictate single pole switching, regardless of transient
Page 45 of 50
power limits. Because of the uncertainties of reclosing near generating stations,
application practices vary widely and many include one or more of the following:
[16, 17]
1. Delayed reclosing for all faults (e.g., 10 seconds or more to allow decay of
oscillations)
2. Sequential reclosing, remote end first.
3. Selective HSR (e.g., Single pole operation or other type of relaying
designed to avoid reclosing on multiphase faults)
4. No automatic reclosing at all.
Delayed reclosing for all faults:
One recommended alternative to HSR is to allow enough dead time (delay reclosing)
for the torsional shaft oscillations produced by the initial fault to decay [16]. The
damping of the subsynchronous resonant oscillations (SSR) is the damping due to the
twisting of the turbine-generator interconnecting shaft and the damping associated
with the oscillations of the turbine blades due to interaction with the steam.
Studies indicate that damping of the SSR oscillations is a function of load and is
dominated by the steam-turbine blade interaction [9]. One study shows that damping
time constants range from 8 to 30 seconds, depending on the level of excitation (due
to switching, HSR, etc.). Reclosing delays of 10 seconds have been recommended in
some studies. Studies have also shown that models can be used to determine the
torques that result on the turbine-generator due to various disturbances in the power
system. This, by itself, doesnot determine the amount of damage these torques cause
to the turbine-generator. A suggested fatigue model used for the evaluation of this
damage is very complex and uses assumptions based on both empirical and statistical
methods. This fact must be recognized when interpreting any results using this
model. It is suggested that fatigue cannot be directly correlated to simple measures,
such as the shaft's peak torque following a disturbance, but that it is a cumulative
effect related to the overall nature of the torque transient.
Further study in the area of torsional fatigue is suggested to improve techniques for
predicting accumulating damage.
Page 46 of 50
Sequential reclosing:
Reclosing the remote end of a line with generation will result in reduced torsional
stress on the generator, provided the remote end is electrically removed enough from
the generator.
Various studies have concluded that significant shaft damage is possible when high-
speed reclosing into a close-in, three-phase fault. However, at least one study shows
no significant damage for any fault where HSR is successful or for any line-ground
fault even where HSR is not successful [16].
Past practices of eliminating HSR near generator sites are being challenged by recent
studies. It has been suggested that HSR not be eliminated at these sites unless it can
be shown, for a specific situation, that the risk of shaft damage is significant. High-
speed reclosing near generator sites has the potential to enhance system reliability
and maintain generation that would otherwise be lost during system disturbances, and
these recent studies indicates possible review of existing reclosing policies. [18, 19,
20]
In CEB system the three phases AR is always performed after synchrocheck. Hence
it is safe to turn on three phase AR near generator stations.
These studies confirm that it is safer to switch on single phase AR in 220kV lines
connecting generator stations like Norochcholai and Kerawalapitiya power plants.
Page 47 of 50
Chapter 6
CONCLUSION & RECOMMENDATIONS
6.1. Recommended settings for 220kV Transmission Lines
Based on the analysis of existing settings and PSSE simulations recommended dead
times for three phase AR of 220kV lines can be summarized in table 6.1.
Table 6.1 – Recommended AR settings for 220kV transmission lines
Line Synchro Check Dead Time
Substation at one end LB/LL 750ms
Substation at the other end LB/LL & LB/DL 550ms
The substation nearer to generating station shall employ the longer dead time.
A dead time of 450ms is adequate to clear any transient fault which is proven by
analyzing DDR records. Hence for single phase AR of 220kV transmission line a
Dead Time of 450ms is recommended. Single phase AR does not require synchro
check.
6.2. Recommended settings for 132kV Transmission Lines
Analysis of existing settings and PSSE simulations reveal that the existing settings
for most of the 132kV lines are acceptable. But it is recommended to bring the
settings at different stations under a uniform scheme depending on the nature of the
line.
Recommended dead times for highly interconnected 132kV lines are given in table
6.2
Page 48 of 50
Table 6.2 – Recommended AR settings for interconnected 132kV transmission lines
Line Synchro Check Dead Time
Substation at one end LB/LL 800ms
Substation at the other end LB/LL & LB/DL 1100ms
Recommended dead times for tie lines connecting two systems eg. Balangoda - New
Laxapana to maintain stability are shown in table 6.3.
Table 6.3 – Recommended AR settings for 132kV transmission lines connecting two
isolated networks
Line Synchro Check Dead Time
Substation at one end LB/LL & LB/DL 300ms
Substation at the other end LB/LL 500ms
Further it is recommended to switch on AR on all transmission lines after revising
the AR settings accordingly.
6.3. AR of Generator feeders
It is recommended to switch on single phase AR near generating stations when
connected through 220kV transmission lines.
It is advisable to have longer dead times near generating stations to limit thermal/
mechanical stresses on the generators and then switch on AR to improve reliability.
In such situations the remote end should reclose first.
Page 49 of 50
References
[1] IEEE Power Systems Relaying Committee; Automatic Reclosing of
Transmission Lines; IEEE Transactions, Vol. PAS-103, Feb. 1984, no. 2,
pages 234 - 245
[2] Protection Relay Application Guide; GEC Measurements, 1975
[3] Kimbark, Edward Wilson, ScD; Power System Stability; John Wiley & Sons,
Inc.,N.Y., London
[4] Lahmeyer International, “Review of protection system and settings of CEB
transmission network”, 1996
[5] PB Power, “Report on the CEB transmission system and organizational
arrangements for operation and maintenance”, Volume 4, October 1999
[6] Ceylon Electricity Board, Transmission Plan, 1999
[7] Ceylon Electricity Board, “Long Term Transmission Development Plan
2011-2020”, July 2011.
[8] Jan Machowski, Janusz W. Bialek, James R. Bumby; Power System
Dynamics Stability and Control ; Second Edition, John Wiley & Sons Ltd.,
2008
[9] Basler Protective Relay Technical Papers; “Automatic Reclosing -
Transmission Line Applications and Considerations”, Available:
http://www.basler.com, accessed on January 2009
[10] Siemens Energy, Inc., “PSS®E 32.0 Program Operation Manual”, Revised
June 2009
[11] Ahn S. P., Kim C. H., Aggarwal R.K. and Johns A. T., “An alternative
approach to adaptive single pole auto-reclosing in high voltage transmission
systems based on variable dead time control,” IEEE Transaction on Power
Delivery, Vol. 16, No. 4, pp. 676-686, October 2001.
Page 50 of 50
[12] Bo Z. Q., Aggarwal R. K. and Johns A. T., “A novel technique to distinguish
between transient and permanent fault based on detection of current
transients,” Proceeding of 4th International Conference on Advances in
Power System Control and Management, APSCOM-97, Hong Kong, pp. 217-
220, November 1997.
[13] Bowler C. E. J., Brown P. G. and Walker D. N., “Evaluation of the effect of
power circuit breaker reclosing practices on turbine-generator shaft,” IEEE
Transaction on Power Apparatus System, Vol. PAS-99, pp. 1764-1779, 1980.
[14] Walter A. Elmore; “ Protective Relaying Theory and Applications”, ABB
Power T&D Company Inc., Relay Division, Coral Springs, Florida, Chapter
15, 1994
[15] The Electricity Training Association, “Power System Protection”, The
Institution of Electrical Engineers, Volume 3, 1997
[16] M.C. Jackson, et al.; Turbine Generator Shaft Torque and Fatigue: Part I –
Simulation Methods and Fatigue Analysis; IEEE Transactions, Vol. PAS-98,
1979, pages 2299-2307, Part I
[17] M.C. Jackson, et al.; Turbine Generator Shaft Torque and Fatigue: Part II -
Impact of System Disturbances and High-speed Reclosing; IEEE
Transactions, Vol. PAS-98, 1979, pages 2308-2313, Part II
[18] P. Kundor: Power System Stability and Control: New York: McGraw-Hill,
1994.
[19] Vibration Signatures R. Oliquino, Jr., S. Islam, SMIEEE and H. Eren,.;
Effects of Types of Faults on Generator; School of Electrical and Computer
Engineering, Curtin University of Technology, Western Australia
[20] IEEE Power Systems Relaying Committee Working Group; "Single Phase
Tripping and Auto Reclosing of Transmission Lines,"; IEEE Transactions on
Power Delivery, vol. 7, 1992.
Appendix A failure incidents of Biyagama ‐ Kothmale 220 kV Transmission lines
Date Tripped Station Equipment No.Volt. Level (kV)
Relay operated & indicationsObservation (Actual fault /Mal operation /Any other Remarks)
2010.03.11 13.08 Kothmale Biyagama 1 220 REL521 - VTSZ , VTRIP , REL511 - VTSZ , VTSP, TP
2010.03.11 13.08 Biyagama Kothmale 1 220 DEF.2010.08.07 17.03 Biyagama Kotmale 2 132 RAAM (AR Relay) - Relay operated2010.08.07 17.03 Kotmale Biyagama 2 132 REL 521 - Auto Reclosed2010.09.30 18.12 Biyagama Kotmale 1 220 THR - Zone 1, R Phase, EF RAZFE - RN, U2010.09.30 18.12 Biyagama Kotmale 2 220 RHIDF2H - OC R Phase RAZFE - RN, U
2010.09.30 18.12 Kotmale Biyagama 1 220 REL 521 (M1) - IMP-PSL1, IMP-PSN, IMP-ZM3, CR<Z, EF-STEF, AR INPROGR
2010.09.30 18.12 Kotmale Biyagama 2 220REL 521 (M1) - IMP-PSL1, IMP-PSN, IMP-ZM3, CR<Z, EF-STEF, AR INPROGR, IMP-TRC, TRIP-
GTRIP, IMP-ZM2, TRIP- SPTRIP2010.11.28 14.39 Biyagama Kotmale 1 220 RAZFE - RN, U THR - EF-R
2010.11.28 14.39 Biyagama Kotmale 2 220 RAZFE - RN, TN, U 7SA 522 - PICK UP L3, PICK UP E, CARRIER SEND
2010.11.28 14.39 Kotmale Biyagama 1 220
REL 521 (M1) - IMP-PSL1, IMP-PSN, IMP-ZM1, IMP-ZM2, IMP-ZM3, CSZ, TR-Z1, TR-SOTF, AR INPROGR, TRIP-GTRIP, TRIP- SPTRIP, TRIP-
TPTRIP REL 316 - Start R, Start E, Delay 1, AR in progress, Com send
2010.11.28 14.39 Kotmale Biyagama 2 220
REL 521 (M1) - IMP-PSL1, IMP-PSN, IMP-ZM1, IMP-ZM2, IMP-ZM3, CSZ, TR-Z1, TR-SOTF, AR INPROGR, TRIP-GTRIP, TRIP- SPTRIP, CRZ< REL 316 - Start R, Start B, Start E, Delay Z1, AR
in progress
2010.11.28 14.42 Biyagama Kotmale 2 220 RAZFE - TN
2010.11.28 14.42 Kotmale Biyagama 2 220
REL 521 (M1) - IMP-PSL3, IMP-PSN, IMP-ZM1, IMP-ZM2, IMP-ZM3, TRC, CSZ, TR-Z1, Hװ - TROCL3, AR INPROGR, TRIP-GTRIP, TRIP-
SPTRIP, CRZ< REL 316 - Start B, Start E, Delay Z1, AR in progress, Com send
Actual fault.
Biyagama - Kotmale line 2 was not auto reclosed because fault cleared at Biyagama
end by Backup protection. M1 & M2 relays at Biyagama end failed to clear the fault.
Actual fault.
Annex1 Biya_Koth Trippings 1
Date Time Station Equipment No kV Relay operated & indications Observation
28-Nov-10 14.42 Biyagama Kotmale 2 220 RAZFE - TN Major System failure, A separate report prepaired
28-Apr-08 17.28 Biyagama Kothmale 2 220THR - Zone 1 , Phase Y , B , EF - Y , B Total Failure.( A separate report prepared )
28-Nov-10 14.39 Biyagama Kotmale 1 220 RAZFE - RN, U THR - EF-R Major System failure, A separate report prepaired
28-Nov-10 14.39 Biyagama Kotmale 2 220
RAZFE - RN, TN, U 7SA 522 - PICK UP L3, PICK UP E, CARRIER SEND Major System failure, A separate report prepaired
18-Apr-08 19.55 Biyagama Kothmale 1 220 RAZFE - U , TN Actual fault.
11-Feb-09 14.36 Biyagama Kothmale 2 220 Inter trip received. A separate report submitted.
11-Feb-09 14.36 Biyagama Kothmale 1 220 Inter trip received. A separate report submitted.
01-Jun-08 13.45 Biyagama Kothmale 2 220
THR - Zone 1 , Earth - B. RAZFE - U , TN. , Pole Discordance operated. Further analysis required.
27-May-08 13.24 Biyagama Kothmale 2 220THR - Zone 1 , 2 , Phase - yb , Earth -y Actual fault.
07-Aug-10 17.03 Biyagama Kotmale 2 132RAAM (AR Relay) - Relay operated Actual fault.
11-Mar-10 13.08 Biyagama Kothmale 1 220 DEF. Actual fault.
06-Dec-09 16.34 Biyagama Kotmale 1 220 RAZFE - U , 3Ø Actual fault.
06-Dec-09 16.34 Biyagama Kotmale 2 220 RAZFE - RN , 2Ø Actual fault.
30-Sep-10 18.12 Biyagama Kotmale 1 220THR - Zone 1, R Phase, EF RAZFE - RN, U
Biyagama - Kotmale line 2 was not auto reclosed because fault cleared at Biyagama end by Backup protection. M1 & M2 relays at Biyagama end failed to clear the fault.
30-Sep-10 18.12 Biyagama Kotmale 2 220RHIDF2H - OC R Phase RAZFE - RN, U
Biyagama - Kotmale line 2 was not auto reclosed because fault cleared at Biyagama end by Backup protection. M1 & M2 relays at Biyagama end failed to clear the fault.
24-May-11 23.48 Biyagama Kotmale 1 220RAZFE - SN, U THR - EF-Y, Auto Reclosed Actual fault
28-Apr-08 17.28 Biyagama Kothmale 1 220RAZFE - U , 2Ø , THR - Phase Y , B , Earth Y , B . Total Failure.
20-Feb-11 17.51 Biyagama Kotmale 2 220
RAZFE - TN, U 7SA 522 - Trip phase 1, Z1, Z1 B, Carrier send, Carrier receive
27-May-11 3.40 Biyagama Kotmale 2 220
RAZFE - TN, U 7SA 522 - Trip phase L1, Z1, CR, CS Auto Reclosed Actual fault
27-May-11 3.40 Biyagama Kotmale 1 132RAZFE - U THR - EF-B, Auto Reclosed Actual fault
20-Feb-11 17.51 Biyagama Kotmale 1 220 RAZFE - UN, U THR - EF-B
Appendix B Tripping of Veyangoda ‐ Norochcholai 220 kV Transmission lines
Date Tripped Station Equipment No.Volt. Level (kV)
Relay operated & indicationsObservation (Actual fault /Mal operation /Any other Remarks)
16.07.2012 0.30 Norochchole Veyangoda 1 220(M1) NARI RCS 931 AM - OP –Z-DPFC-ABC-8ms, OP-Diff-ABC-13ms, OP-Z1 –ABC-20ms, Fault location ABC-3.6 km SAC PSL602GCM - - Indications not recorded.
16.07.2012 0.30 Veyangoda Norochchole 1 220
Interposing relay set - Trip Coil 1, Phase A trip, CB reclose, AR operate NARI RCS 931- AM - Trip A,Reclose OP –Diff OP-AR Fault location 00.30-107.6 km SAC PSL602GCM - Z-S-Z-mo2 tr, pilot fault.
04.08.2012 22.09 Norochchole Veyangoda 2 220NARI RCS 931- AM - Indications not recorded. SAC PSL602GCM - Dis.&-z-s.pro.st, Distance = 40m
04.08.2012 22.09 Veyangoda Norochchole 2 220
Interposing relay set - Trip Coil 1 - PhaseC trip, CB reclose, AR operate NARI RCS 931- AM - Trip C, Reclose SAC PSL602GCM - Trip, Reclose
05.08.2012 1.59 Norochchole Veyangoda 2 220NARI RCS 931- AM - Indications not recorded. SAC PSL602GCM - Dis.&-z-s.pro.st, Distance = 70m
05.08.2012 1.59 Veyangoda Norochchole 2 220
Interposing relay set - Trip Coil 1 - Phase C trip, CB reclose, AR operate NARI RCS 931- AM - Trip C, Reclose SAC PSL602GCM - Trip, Reclose
08.08.2012 5.57 Norochchole Veyangoda 1 220NARI RCS 931 AM - OP–ZDPFC, OP-Diff, OP-Z1, Fault location 11.4 km SAC PSL602GCM - - Indications not recorded.
08.08.2012 5.57 Veyangoda Norochchole 1 220
Interposing relay set - Trip Coil 1 - Phase C trip, CB reclose, AR operate NARI RCS 931- AM - Trip C, Fault location = 70.5 km, Reclose SAC PSL602GCM - Trip, Reclose
Line was auto-reclosed from Veyangoda end. Actual Fault
Line was auto-reclosed from Veyangoda end. Actual Fault
Line was auto-reclosed from Veyangoda end. Actual Fault
Line was auto-reclosed from Veyangoda end. Actual Fault. Fault currents in Veyangoda R
phase = 1073 A. Y Phase = 534 A. B Phase = 3060 A Fault currents in Norochchole R phase = 1101 A. B Phase = 384 A. Y Phase = 4131
A
Appendix C AR Status of 132kV Transmission lines
StationLine Status Remarks
Habarana Habarana - Old Anuradapura 02 OFF due to pneumatic CB
Habarana Habarana - Old Anuradapura 01 ON
Habarana Habarana - Ukuwela 02 OFF due to pneumatic CB
Habarana Habarana - Ukuwela 01 ON
Habarana Habarana - Valachchena OFF due to pneumatic CB
New Anuradapura New Anuradapura - Kothmale 02 ON
New AnuradapuraNew Anuradapura - Old Anuradapura 02 OFF Reason Unknown
New AnuradapuraNew Anuradapura - Old Anuradapura 01 OFF Reason Unknown
New Anuradapura New Anuradapura - Trinkomale 01 OFF Reason Unknown
New Anuradapura New Anuradapura - Trinkomale 02 OFF Reason Unknown
New Anuradapura New Anuradapura - Vaunia 01 ON
New Anuradapura New Anuradapura - Vaunia 02 ON
Norechchole Norechchole-Veyangoda 01 OFF Reason Unknown
Norechchole Norechchole-Veyangoda 02 OFF Reason Unknown
Old Anuradapura Old Anuradapura - Habarana 01 ON
Old Anuradapura Old Anuradapura - Habarana 02 ON
Old AnuradapuraOld Anuradapura - New Anuradapura 02 ON
Old AnuradapuraOld Anuradapura - New Anuradapura 01 ON
Old Anuradapura Old Anuradapura - Puttalam 02 ON
Old Anuradapura Old Anuradapura - Puttalam 01 ON
Pannala Pannala - Katunayaka ON
Pannala Pannala - Puttalam ON
Puttalam Puttalam - Chilaw ON
Puttalam Puttalam - Pannala ON
Puttalam Puttalam - Old Anuradapura 02 ON
Puttalam Puttalam - Old Anuradapura 01 ON
Trinkomale Trinkomale - New Anuradapura 02 - Not Available
Trinkomale Trinkomale - New Anuradapura 01 - Not Available
Ukuwela Ukuwela - Bowatanna - Not Available
Ukuwela Ukuwela- Habarana 01 - Not Available
Ukuwela Ukuwela- Habarana 02 - Not Available
Ukuwela Ukuwela- Kiribathkubura 02 - Not Available
Ukuwela Ukuwela- Kiribathkubura 01 - Not Available
StationLine Status Remarks
Valachchane Valachchane-Habarana - Not Available
Valuniya Vavuniya-New Anuradhapura 01 - Not Available
Valuniya Vavuniya-New Anuradhapura 02 - Not Available
Athurugiriya Athurugiriya - Polpitiya 02 ON
Athurugiriya Athurugiriya - Polpitiya 01 ON
Athurugiriya Athurugiriya-Kolonnawa 01 ON
Athurugiriya Athurugiriya-Kolonnawa 02 ON
Athurugiriya Athurugiriya - Oruwala 01 ON
Athurugiriya Athurugiriya - Oruwala 02 ON
Aniyakanda Aniyakanda-Kotugoda ON
Aniyakanda Aniyakanda-Keleniya ON
Barge Barge - Kelanitissa Not Available
Biyagama Biyagama - Kelanitissa 01 ON
Biyagama Biyagama - Kelanitissa 02 ON
Biyagama Biyagama - Kothmale 01 ON
Biyagama Biyagama - Kothmale 02 ON
Biyagama Biyagama - Pannipitiya 01 OFF
Biyagama Biyagama - Pannipitiya 02 OFF
Biyagama Biyagama - Sapugaskanda 01 ON
Biyagama Biyagama - Sapugaskanda 02 ON
Biyagama Biyagama-Kotugoda 01 ON
Biyagama Biyagama-Kotugoda 02 ON
Biyagama Biyagama - Sapugaskanda PS 01 OFF
Biyagama Biyagama - Sapugaskanda PS 02 OFF
Bolawatta Bolawatta Incoming 01 ON
Bolawatta Bolawatta Incoming 01 ON
Dehiwala Dehiwala-Htown OFF
Dehiwala Dehiwala-pannipitiya OFF
Heladhanvi Heladhanavi - Puttalam 01 Not Available
Heladhanvi Heladhanavi - Puttalam 02 Not Available
Htown Htown-Dehiwala Not Available
Htown Htown-Maradana Not Available
Horana Horana-Pannipitiya ON
Horana Horana-Matugama 01 ON
StationLine Status Remarks
Katunayaka Katunayaka-Kotugoda 01 ON
Katunayaka Katunayaka-Kotugoda 02 ON
Katunayaka Katunayaka-Chilaw ON
Katunayaka Katunayaka-Pannala ON
Kelanitissa Kelanitissa - Barge Not Available
Kelanitissa Kelanitissa - Biyagama 01 ON
Kelanitissa Kelanitissa - Biyagama 02 ON
Kelanitissa Kelanitissa - Kolonnawa 02 ON
Kelanitissa Kelanitissa - Kolonnawa 01 ON
Kelanitissa Kelanitissa - Sub F Not Available
Kelanitissa Kelanitissa - Sub C Not Available
Kelaniya Kelaniya - Aniyakanda ON
Kelaniya Kelaniya - Kotugoda 01 ON
Kelaniya Kelaniya -Kolonnawa 01 ON
Kelaniya Kelaniya -Kolonnawa 02 ON
Kelaniya Kelaniya-Sapugaskanda 02 ON
Kelaniya Kelaniya-Sapugaskanda 01 ON
Kelaniya Kelaniya-KHD 01 ON
Kelaniya Kelaniya-KHD 02 ON
KHD KHD - Kelaniya 01 Not available
KHD KHD - Kelaniya 02 Not available
Kolonnawa Kolonnawa - Athurugiriya 02 ON
Kolonnawa Kolonnawa - Athurugiriya 01 ON
Kerawalapitiya GS Kerawalapitiya GS-Kerawala PS 01 Not available
Kerawalapitiya GS Kerawalapitiya GS-Kerawala PS 02 Not available
Kerawalapitiya GS Kerawalapitiya GS-Kotugoda01 OFF
Kerawalapitiya GS Kerawalapitiya GS-Kotugoda02 OFF
Kerawalapitiya PS Kerawalapitiya GS-Kerawala PS 01 Not available
Kerawalapitiya PS Kerawalapitiya GS-Kerawala PS 02 Not available
Kolonnawa Kolonnawa - Kelanitissa 02 ON
Kolonnawa Kolonnawa - Kelanitissa 01 ON
Kolonnawa Kolonnawa - Kelaniya 01 ON
Kolonnawa Kolonnawa - Kelaniya 02 ON
Kolonnawa Kolonnawa - Kosgama 04 ON
StationLine Status Remarks
Kolonnawa Kolonnawa - Pannipitiya 01 OFF
Kolonnawa Kolonnawa - Pannipitiya 01 OFF
Kolonnawa Kolonnawa - Seethawaka 03 ON
Kolonnawa Kolonnawa - Sub E Not available
Kolonnawa Kolonnawa - Sub C Not available
Kolonnawa Kolonnawa - Maradana Not available
Kosgama Kosgama - Polpitiya 04 ON
Kosgama Kosgama- Kolonnawa 04 ON
Kotugoda Kotugoda -Aniyakanda ON
Kotugoda Kotugoda - Kelaniya 01 ON
Kotugoda Kotugoda - Katunayaka 02 ON
Kotugoda Kotugoda - Katunayaka 01 ON
Kotugoda Kotugoda - Biyagama 02 ON
Kotugoda Kotugoda - Biyagama 01 ON
Kotugoda Kotugoda - Veyangoda 02 Intergration pos.
Kotugoda Kotugoda - Veyangoda 01 Intergration pos.
Kotugoda Kerawalapitiya GS-Kotugoda01 OFF
Kotugoda Kerawalapitiya GS-Kotugoda02 OFF
Madampe Madampe -Puttalam ON
Madampe Madampe -Katunayaka ON
Maradana Maradana-Htown Not available
Maradana Maradana-kolonnawa Not available
Oruwala Oruwala Incoming 02 Not available
Oruwala Oruwala Incoming 01 Not available
Panadura Paanipitiya / Mathugama OFF
Panadura Paanipitiya / Horana OFF
Pannipitiya Pannipitiya - Biyagama 01 ON
Pannipitiya Pannipitiya - Biyagama 02 ON
Pannipitiya Pannipitiya - Horana 01 ON
Pannipitiya Pannipitiya - Kolonnawa 01 ON
Pannipitiya Pannipitiya - Kolonnawa 02 ON
Pannipitiya Pannipitiya - Matugama 02 ON
Pannipitiya Pannipitiya - Rathmalana 01 Not available
Pannipitiya Pannipitiya - Rathmalana 02 Not available
StationLine Status Remarks
Pannipitiya Pannipitiya - Dehiwala OFF
Rathmalana Rathmalana - Pannipitiya 01 Not available
Rathmalana Rathmalana - Pannipitiya 02 Not available
Sapugaskanda G/S Sapugaskanda -Kelaniya 01 OFF
Sapugaskanda G/S Sapugaskanda -Kelaniya 02 OFF
Sapugaskanda G/S Sapugaskanda -Biyagama 01 OFF
Sapugaskanda G/S Sapugaskanda -Biyagama 02 OFF
Sapugaskanda P/S Sapugaskanda P/S - Biyagama 01 OFF
Sapugaskanda P/S Sapugaskanda P/S - Biyagama 02 OFF
Seethawaka Seethawaka-Kolonnawa ON
Seethawaka Seethawaka-Polpitiya ON
Sub E Sub E - Kolonnawa Not available
Sub E Sub E - Sub F Not available
Sub F Sub F - Kelanitissa Not available
Sub F Sub F - Sub E Not available
Sub C Sub C - Kelanitissa Not available
Sub C Sub C - Kolonnawa Not available
Sri'Japura Sri'Japura Incoming 01 ON
Sri'Japura Sri'Japura Incoming 02 ON
Veyangoda Veyangoda - Kotugoda 01 ON
Veyangoda Veyangoda - Kotugoda 02 ON
Veyangoda Veyangoda - Norecchole 01 ON
Veyangoda Veyangoda - Norechchole 02 ON
Balangoda Balangoda - New Laxapana 01 ON
Balangoda Balangoda - New Laxapana 02 ON
Balangoda Balangoda - Rathnapura 01 ON
Balangoda Balangoda - Rathnapura 02 ON
Balangoda Balangoda - Samanalawewa 01 ON
Balangoda Balangoda - Samanalawewa 02 ON
Balangoda Balangoda -Galle ON
Balangoda Balangoda -Deniyaya ON
Deniyaya Deniyaya-Balangoda ON
Deniyaya Deniyaya-Galle ON
Embilipitiya Embilipitiya - ACE Line 1 - Not Available
StationLine Status Remarks
Embilipitiya Embilipitiya - ACE Line 2 - Not Available
Embilipitiya Embilipitiya - Hambantota 01 ON
Embilipitiya Embilipitiya - Hambantota 02 ON
Embilipitiya Embilipitiya - Matara ON
Embilipitiya Embilipitiya - Beliaththa ON
Embilipitiya Embilipitiya - Samanalawewa 01 - Not Available
Embilipitiya Embilipitiya - Samanalawewa 02 - Not Available
kukule Kukule-Mathugama 01 ON
kukule Kukule-Mathugama 02 ON
Galle Galle - Deniyaya - Not Available
Galle Galle - Balangoda - Not Available
Hambantota Hambantota - Embilipitiya 01 - No CB
Hambantota Hambantota - Embilipitiya 02 - No CB
Matara Matara - Embilipitiya ON
Matara Matara - Beliaththa ON
Matugama Matugama - Horana ON
Matugama Matugama - Pannipitiya ON
Matugama Kukule-Mathugama 01 ON
Matugama Kukule-Mathugama 02 ON
Matugama Mathugama-Ambalangoada 01 ON
Matugama Mathugama-Ambalangoada 02 ON
Ambalangoda Ambalangoada-Mathugama 01 ON
Ambalangoda Ambalangoada-Mathugama 02 ON
Rathnapura Rathnapura - Balangoda 01 ON
Rathnapura Rathnapura - Balangoda 02 ON
Samanalawewa Samanalawewa - Balangoda 01 ON
Samanalawewa Samanalawewa - Balangoda 02 ON
Samanalawewa Samanalawewa - Embilipitiya 02 ON
Samanalawewa Samanalawewa - Embilipitiya 01 ON
ACE Emb ACE-Emb - Embilipitiya 01 - Not Available
ACE Emb ACE-Emb - Embilipitiya 02 - Not Available
Beliaththa Beliaththa-Matara ON
Beliaththa Beliaththa-Embilipitiya ON
Ampara Ampara - Badulla 01 ON
StationLine Status Remarks
Badulla Badulla - Rantambe 01 ON
Badulla Badulla - Rantambe 02 - Not Available
Badulla Badulla - Old Lax. 02 ON
Badulla Badulla - Old Lax. 01 ON
Badulla Badulla-Ampara 01 - Not Available
Bowatanna Bowatanna -Ukuwela - Not Available
Canyon Canyon - New laxapana . ON
Inginiyagala Inginiyagala incoming 01
Kiribathkubura Kiribathkubura - Kurunagala 01 ON
Kiribathkubura Kiribathkubura - Kurunagala 02 OFF Reason Unknown
Kiribathkubura Kiribathkubura - Ukuwela 01 OFF Reason Unknown
Kiribathkubura Kiribathkubura - Ukuwela 02 ON
Kiribathkubura Kiribathkubura - Polpitiya 01 OFF Reason Unknown
Kiribathkubura Kiribathkubura - Polpitiya 02 OFF Reason Unknown
Kothmale Kothmale - Biyagama 01 ON
Kothmale Kothmale - Biyagama 02 ON
Kothmale Kothmale - New Anuradapura 02 ON
Kothmale Kothmale - Victoria 01 ON
Kothmale Kothmale - Victoria 02 ON
Kurunagala Kurunagala - Kiribathkubura 01 OFF
Kurunagala Kurunagala - Kiribathkubura 02 OFF
New Laxapana New Laxapana - Balangoda 01 OFF
New Laxapana New Laxapana - Balangoda 02 OFF
New Laxapana New Laxapana - Canyon.
-
New Laxapana New Laxapana - Old Laxapana 01
-
New Laxapana New Laxapana - Old Laxapana 02
-
New Laxapana New laxapana - Polpitiya 01 OFF
New Laxapana New laxapana - Polpitiya 02 OFF
Nuwaraeliya Nuwaraeliya Incoming 02 ON
Nuwaraeliya Nuwaraeliya Incoming 01 ON
Old Laxapana Old Laxapana - New Laxapana 01 ON
Old Laxapana Old Laxapana - New Laxapana 02 ON
Old Laxapana Old Laxapana - Polpitiya 01 ON
Old Laxapana Old Laxapana - Polpitiya 02 ON
StationLine Status Remarks
Old Laxapana Old Laxapana - WPS 01 ON
Old Laxapana Old Laxapana - WPS 02 ON
Old Laxapana Old Laxapana -Badulla 01 ON
Old Laxapana Old Laxapana -Badulla 02 ON
Polpitiya Polpitiya - Athurugiriya 02 ON
Polpitiya Polpitiya - Athurugiriya 01 ON
Polpitiya Polpitiya - Kiribathkubura 01 ON
Polpitiya Polpitiya - Kiribathkubura 02 ON
Polpitiya Polpitiya - Kosgama ON
Polpitiya Polpitiya - New Laxapana 01 ON
Polpitiya Polpitiya - New Laxapana 02 ON
Polpitiya Polpitiya - Old Laxapana 01 ON
Polpitiya Polpitiya - Old Laxapana 02 ON
Polpitiya Polpitiya - Seethawaka ON
Randenigala Randenigala - Rantambe - Not Available
Randenigala Randenigala - Victoria - Not Available
Rantambe Rantambe - Randenigala ON
Rantambe Rantambe -Badulla 01 ON
Rantambe Rantambe -Badulla 02 ON
Thulhiriya Thulhiriya Incoming 01 ON
Thulhiriya Thulhiriya Incoming 02 ON
Victoria Victoria - Kothmale 02 OFF Reason Unknown
Victoria Victoria - Kothmale 01 OFF Reason Unknown
Victoria Victoria - Randenigala OFF Reason Unknown
WPS WPS - Old Laxapana 01 - Not Available
WPS WPS - Old Laxapana 02 - Not Available
1130POLPI-1
132.2
1170SAMAN-1
129.3
1210BOWAT-1
132.2
1770KIRIB-1
2220KOTMA-2
222.3
2230VICTO-2
224.4
2240RANDE-2
225.4
2250RANTE-2
225.4
32.7
32.6
3620BADUL-3
32.8
12.6
4252RANTE-G2
1790RATMA-1
132.4
1300KELAN-1
132.7
132.6
4760COL_F-11
10.9
4750COL_E-11
131.1
3500KOSGA-3
33.1
33.1
3670MATARA-3
132.0
33.3
132.0
3520NUWAR-3
33.3
1520NUWAR-1
130.7
1620BADUL-1
130.5
131.2
3540ORUWA-3
33.0
1670MATARA-1
125.8
132.3
1660EMBIL-1
1100LAX-1
132.0
131.3
3200UKUWE-3
3530THULH-3
33.0
32.7
217.2
2300KELAN-2
216.2
1540ORUWA-1
132.1
1530THULH-1
131.2
132.3
218.4
33.1
3860MADAM-3
132.6
225.3
1705NEWANU-1
133.5
1700ANURA-1
1850PANAD-1
132.4
1800MATUG-1
132.6
132.6
1240VAVUN-1
3240VAVUN-33
32.9
32.8
32.7
127.4
3400HAMBA-33
33.0
3660EMBIL-3
32.9
32.7
33.4
1160INGIN-1
127.0
3160INGIN-3
125.7
33.3
3700ANURA-3A
216.2
32.9
33.0
1710TRINC-1
33.0
132.1
32.9
32.9
131.8
32.7
3690HABAR-3
33.0
1740RATNAP-1
129.633.2
1595KHD -1
132.2
133.3
1600BOLAW-1
131.032.6
132.2
32.6
1840JPURA_1
132.4
3840JPURA_3
131.9
132.0
132.3
10.9
4435COL_A_11
3890DEHIW_3
33.0
3800MATUG-3
33.0
1810PUTTA-1
135.1
33.7
2.8
0.92.8
0.9
3.8
9.6
3.8
9.6
5.2
9.9
5.2
9.9
23.0
3.823.0
3.8
25.5
5.1
25.3
3.9
40.2
1.1
40.2
1.1
0.6
9.230.8
14.3
5.6
3.0
18.4
9.4
5.4
24.0
14.6
17.3
7.2
21.8
9.8
3.9
12.0 6.6
8.1
5.6
8.2
17.3
28.6
5.5
28.3
4.6
9.6
7.1
5.1
10.4
1.2
10.4
1.2
14.6
3.0
14.4
5.0
23.1
3.1
23.1
15.1
9.0
3.6
3.6
2.222.9
2.1
0.0
0.0
0.0
6.7
11.4
13.9
4.5
10.0
4.7
0.0
1.9 0.0
1.9
0.0
0.0
0.0
0.0
104.2
34.6
103.5
42.8
104.2
34.6
103.5
42.8
2.8
0.2
2.8
0.2
2.6
1.4
0.1
16.7
3.4
64.5
46.1
64.5
46.1
0.0
43.9
43.9
6.1
3.1
3.3
17.3
10.9 17.3
10.9
34.6
21.8
7.8
2.6
1.2
0.4
0.0
0.0
21.5
3.621.5
3.6
0.0
0.5
0.0
0.0
40.6
40.1
0.0 0.0
0.0
0.4
1.8
11.1
6.9
0.4
1.8
23.0
12.6
5.4
7.6
19.5
75.9
27.7
76.1
75.9
27.7
76.1
27.1
22.3
1.9
9.6
9.6
0.7
13.3
1.2
13.2
2.3
1.3
0.2
1.3
0.2
2.5
4.5
48.0
44.2
48.1
48.0
44.2
48.1
43.0
20.6
0.0
0.0
23.4
18.9
30.0
5.430.0
5.4
27.3
17.8
0.2
89.2
6.1
89.1
6.689.2
6.1
89.1
6.6
77.1
13.777.1
13.7
9.5
54.9
28.9 54.9
28.9
6.8
0.0
12.0
20.0
26.2
14.8 46.9
19.4
67.0
12.8
20.6
11.3
11.3
6.7
6.2
3.6
1.2
6.3
6.3
2.8
12.6
4.6
19.0
8.4
16.7
19.5
6.7
19.0
2.3
19.2
0.3
18.4
10.7
9.2
5.3
9.2
5.3
1.0
000 30.8
14.8
8.1
8.1
8.2
0.0
16.4
1.6
16.4
1.6
8.3
7.3
0.2
7.3
0.2
23.0
53.8
23.0
51.8
23.0
53.8
23.0
51.8
22.2
30.5
30.5
4.9
4.1
2.9
8.4
1
23.1
8.2
L
37.0
17.0
H
1
1
2.2
1
2.9
1
20.6
10.0
1 25.0
7.0R
1
1 22.9
14.1
1 23.4
16.2
1
17.3
6.7
1
24.0
13.4
1
15.6
8.1
1
17.3
5.6
1
1 34.6
1 4.5
2.3
1 10.0
1 0.0
1
1 34.6
20.1
1
1
0.0
0.0
1
18.4
9.4
1
24.5
1
7.8
2.4
SW 0.0
1
1
1.2
1
0.0
1 12.6
4.3
23.2
8.2
L
2
37.3
17.0
H
2
25.0L
60.0
25.0L
2
24.0
3.0L
2 24.5
2.0L
1
1
2 40.0
26.0H
1
2
1
22.9
16.7
SW
19.7
1
23.0
11.5
1 22.9
11.0
1
7.5
4.5
SW
1
20.6
1
25.7
1
0.0
0.0
1
27.3
16.6
1
24.0
13.3
1
1
9.5
5.7
1 8.4
6.2
1
1
1 13.9
8.6
1 20.0
11.4
1
20.6
9.0
1 26.2
10.7
1
11.7
6.1
2
5.4R
1
1
30.0
5.4R
1
19.0
11.0SW
1
16.7
8.4
1
1
18.4
1
1 0.0
1 22.3
12.3
1
1.1
1 83.0
SW
10.4
0.033.0
4.5
33.0
6.7
5.6
0.0
3121WIMAL-3B
0.0
60.0
26.9
3780VALACH_3
33.0
131.4
1780VALACH_1
6.8
19.9
0.4
16.2
131.7
27.1
6.6
3.2
3560PANNI-3
30.0
1590SAPUGA-1
18.5
3830VEYAN-33
1250RANTE-1
26.5
75.3
26.5
26.0
11.6
26.0
11.4
18.9
15.7
4.5
26.0
11.6
26.0
15.7
3.3
0.3
2.2
22.9
1 1.6
1.0
25.9
11.7
14.1
25.9
13.2
8.6
3600BOLAW-3
1
1
10.0
1
SW 0.0
1.9
20.0
3.9
19.6
6.5
3.6
1.2
8.4
5.0L
16.0
25.7
18.8
9.3
1 10.0
0.0L
6.2
1
1
10.0
1
1
5.0
0.0R
1
14.5
10.1
4.1
1
129.7
132.5
3880AMBALA
32.8
9.6
6.0
4.8
3.0
4.8
1
9.6
5.8
1
15.6
15.0
7.5
1900PNNALA
11.2
0.9
1.6
14.7
9.1
1910ANIYA
3910ANIYA
15.6
10.0
16.2
1
16.2
10.0
131.7
32.9
1
19.5
10.0
SW
0.0
SW
0.0
20.6
6.7
6.1
6.7
1.6
0.0
11.1
7.9
6.5
3710TRINC-3
SW
1
2
0.0
0.0
0.0
0.0
0.7
3250RANTE-3
3630BALAN-3
0.0
L
0.0
33.3
23.8
10.4
2.3
9.1
3565PANNI-C
10.2
10.0
15.9
2.0
32.6133.3
7.3
2.5
1 7.3
2.3
32.8
1.1 1.1
0.6
13.0
131.4
14.1
5.014.1
5.0
3440KATUNA-3
32.7
1
12.7
9.7
0.0SW
0.0
1 0.0
0.0
3
3811CEMENT
32.8
16.2
131.1
11.2
6.8
6.8
86.5
30.7
86.5
30.7
87.2
14.5
87.2
14.5
8.2
1
1 10.0
0.0L
20.0
2580KOTUG-2
6.1
3.5
SW 0.0
1
219.2
32.6
18.9
216.1
32.9
11.4
4.5
14.1
1
1.3
13.9
7.8
1920SUB-C
132.7
4920SUB C-11
4.0
1
11.0
1760COL_F-1
8.0
33.2
8.0
4.4
11.0
1500KOSGA-1
15.1
22.2
13.7
3.5
13.6
5.0
10.4
8.2
23.0
3.9
22.7
2.0
23.0
3.9
19.8
1
190.0
1.0
000 174.3
29.1
4811PUTT COAL-2
19.8
1 0.0
0.0
43.0
1 15.6
11.2
52.9R
11.4
12.0
0.3
1651GALLE-2
10.9
43.5
0.0
0.0
0.0
0.0
16.7
29.3
32.8
1
5.7
3.2
3.3
1
1
1
1
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
4310SAPUG-P
11.0
1 48.0
32.0H
11.0
1
26.5
20.0H
2 35.5
20.0H 48.0
27.0 62.0
31.0
0.6
32.6
1
8.0
1.0
7.3
15.4
2.8
7.3
4.7
8.0
2560PANNI-2
132.2
2
60.0
19.4R
3
60.0
19.4R
2.8
1550KOLON-1 2
3.4
6.7
0.0
10.9
3302KELAN-3B
1650GALLE-1
2.4
9.2
20.6
4.6
20.6
4.6
1
2.5
3405HAMBA-33
1400HAMBA-1
127.6
4.0
3340BELIATT-3
126.7
1.1
1340BEATT-1
15.3
2.9
32.8
129.8
3.1
19.5
1150AMPA-1
3150AMPA-3
4251RANTE-G1
12.5
1120WIMAL-1
3120WIMAL-3
1110N-LAX-1
6.1
3.3
3650GALLE-3
129.5
3651GALLE-3B
6.7
129.3
1640DENIY-1
3640DENIY-3
3740RATNAP-3
1630BALAN-1
1140CANYO-1
132.0
1.4
1690HABAR-1
3245VAVUN-33
2.3
0.3
1200UKUWE-1
8.5
24.6
3770KIRIB-3
33.1
SW
130.6
0.0
5.6
132.8
131.1
22.7
2.0
2705NEWANU-2
3810PUTTA-3
0.0
4305KERAWALA-G
14.4
1680KURUN-1
3680KURUN-3
SW
75.3
32.8
1860MADAM-1
131.2
4810PUTT COAL-1
1580KOTUG-1
2830VEYAN-2
1830VEYAN-1
13.5
5.7
32.6
3701ANURA-3B
SW
2810PUTTALAM-PS
224.4
1.0
430
11.2
3581KOTU_NEW-3
3580KOTUG-3
32.6
3510SITHA-33
23.4
11.7
1440KATUNA-1
3900PANNAL
15.9
0.0
24.0
14.1
3590SAPUG-3A
33.0
4311SAPUG-P2
1310SAPUG-1P
1870K_NIYA-1
3870K-NIYA-3
SW 0
.0
3820ATURU-3
Present Transmission Network
0.9
1880AMBALA
10.8
1420HORANA_1
131.8
3420HORANA_3
132.2
1890DEHIW_1
20.6
1435COL_A_1
7.0
7.0
9.0
13.9
3301KELAN-3A
30.5
0.0
15.1
3850PANAD-3
12.3
3790RATMA-3A 1560
PANNI-1
10.9
0.0
0.2
1510SITHA-1
15.1
3550KOLON-3A
32.7
3551KOLON-3B
8.0
22.9
1750COL_E-1
2570BIYAG-2
2305KERAWALA_2
218.4
14.4
4306KERAWALA-S
0.9667
* 53.0
2.0
7.5
* 1
2.3
0.9667
1.0000 1.0166
* 53.0
2.0
40.7
7.5
* 1
2.3
6.3
6.3
40.7
1.0000
0.9833
3.2
17.3
4.1
* 2.8
0.7
1.0000
1.0000 0.9833
* 20.1
3.2
17.3
4.1
* 2.8
0.7
133.5
1.1000
1.0000 0.9833
* 54.6
21.5
34.3
35.1
* 2
0.4
1.0000 0.9833
* 54.6 21.5
34.3
35.1
* 2
0.4
10.6
1.0000
1.0000 1.083357.2
23.0
53.4
* 0.0
0.0
1.0000
1.0000 1.0833
* 23.0
57.2
23.0
53.4
* 0.0
0.0
* 23.0
4300GT 07
2222BARGE-2
3300KELANI-3
1.0000
1.0000 1.0493
* 48.0
44.2
48.0
41.7
* 0.0
0.0
1.0000
1.0000 1.0493
* 48.0
44.2
48.0
41.7
* 0
.0
0.0
4302KCCP ST
4301KCCP GT
4303AES GT
4304AES ST
1820ATURU-1
3570BIYAG-3
10.6
1.0000
* 20.1
3705NEWANU-3
1570BIYAG-1
1.1000
40.7
21.2
32.9
128.1
1.01661.0000
1.0
450
4430COL_I_11
19.3
1430COL_I_1
33.0
1410KUKULE-1
Bus - VOLTAGE (kV)Branch - MW/MvarEquipment - MW/Mvar
100.0%RATEA
1.050OV0.950UV
kV: <=60.000 <=120.000 <=200.000 >200.000