GETCO, VadodaraGujarat

GRID OPERATIONAND

MONITORING

Topics covered

� Power System Operation

� Statutory frame work

� Grid Operation Technology - Today

� Grid Operation Technology - Tomorrow

� Defense mechanism for secure and reliable power

system operation - SPS

� Opportunity for research

2

At Present Indian Power SectorFive Region.

– Western Region– Eastern Region– Northern Region– Southern Region– Northern Eastern Region

One Grid:Recently on 31.12.13 , NEW grid hasbeen connected with SR grid through765 KV S/C Solapur – Raichur ACcircuit. Hence, all regions are nowinterconnected and it becomes onegrid.Same frequency at Chennai, Delhi,Ahmedabad, Mumbai, Kolkatta.

Western Region

The western regional grid comprises of the following five states & U/T1. Gujarat 6. U.T. of Diu & Daman2. Maharastra 7. U.T. of Dadra & Nagar Haveli3. Madhya Pradesh4. Chhattisgarh5. Goa

The Western Regional LDC is at Mumbai4

Power System Operation in India

WRLDC SRLDCNRLDCERLDCNERLDC

ISGS / UMPP CTU (ISTS) SLDC Private ISTS Bulk consumerconnected to ISTS

STUState generating StationsState / Private / Renewables

DiscomsState / Private

ISTS

STU

Role and ResponsibilityISO (Independent System Operator)

6

� Grid monitoring and control

� Merit order despatch

� Adhering to system parameters

Voltage – Reactive power management

Frequency – Load – Generation balance, Maintaining Deviation

within limit.

� Energy accounting & settlement

� Declare Capability in energy by the generator for recovery of fix

charge by the generator and Despatch Schedule in energy for the

generator for recovery of fuel charges.

� Unscheduled Interchange settlement (Linked to real time frequency)

� Reactive energy Charges account.

Role and ResponsibilityISO (Independent System Operator)

7

�Analysis of real time / historical data on biannual / annual basis to identify

weak elements in grid and interface with STU for network improvement.

�Assessment of transfer capability in order to facilitate market operation

�Open Access - SLDC is a nodal agency for granting Short Term Open

Access.

�Annual generating unit outage schedule finalization

�Day ahead and in real time EHV line / Equipment outage finalization

�Development and up gradation of SLDC

�Adoption of State of art grid control technology

�RTUs and SCADA Equipment maintenance.

Statutory framework for managing grid operation1. Indian Electricity Grid Code – 2010:

(Hon’ble CERC order No. L-1/18/2010-CERC New Delhi, 28th April 2010)A single set of technical and commercial rules, encompassing all theUtilities connected to/or using the inter-State transmission system(ISTS)�Role of various organizations and linkages:

� Role of NLDC, RLDC, CTU, RPC, CEA SLDC & STU.�Planning code for Inter State Transmission System (ISTS)�Connection code – Basic rules for connectivity with ISTS

�Operating Code:

Provision of RGMO:� For the all thermal generating units of 200 MW and above� All hydro units of 10 MW and above� All governors shall have a droop setting of between 3% and 6%.� Ripple filter shall be +/- 0.03 Hz in order to ignored for load correction

and to prevent governor hunting.8

Statutory framework for managing grid operation

1. Indian Electricity Grid Code – 2010: Contd..

Frequency band (revised in 2nd amendment):

49.90 Hz to 50.05 Hz – w.e.f. 17.02.14.

Voltage Limit :

Special requirement for wind / Solar generators:

System operator shall make all efforts to evacuate the available solar and

wind power and treat as a must-run station. However, System operator

may instruct the solar /wind generator to back down generation on

consideration of grid security or safety of any equipment or personnel is

endangered.9

Statutory framework for managing grid operation1. Indian Electricity Grid Code – 2010: Contd..

Demand estimation for operational planning:

On daily/weekly/monthly/yearly basis for load - generation balance planning

Demand Disconnection:The SLDC through respective State Electricity Boards/Distribution Licenseesshall also formulate and implement state-of-the-art demand managementschemes for automatic demand management like rotational load shedding,demand response.

Outage Planning:�To minimise surplus or deficits, if any, in the system requirement of power andenergy and help operate system within Security Standards.�To optimize the transmission outages of the elements.Recovery procedure:.�Detailed plans and procedures for restoration of the regional grid underpartial/total blackout shall be developed by RLDC and shall be reviewed /updated annually.�Mock trial runs of the procedure for different subsystems shall be carried out atleast once every six months under intimation to the RLDC.

Statutory framework for managing grid operation1. Indian Electricity Grid Code – 2010: Contd..

Scheduling and Despatch Code:Procedure for scheduling and despatch from ISGS.

Statutory framework for managing grid operation

1. Indian Electricity Grid Code – 2010: Contd..

Scheduling of wind and solar energy sources:� With effect from 1.1.2011 Scheduling of wind power generation plants

would have to be done where the sum of generation capacity of suchplants is 10 MW and above and connection point is 33 KV and above,and where PPA has not yet been signed.

� There may be maximum of 8 revisions for each 3 hour time slot startingfrom 00:00 hours during the day.

Statutory frameworkFrequency management linked to penalty

2. Deviation Settlement Regulation – 2014(Hon’ble CERC order No. L-1/132/2013/CERC New Delhi 06th January 2014)

Objective:

�To maintain grid discipline and grid security through the commercial

mechanism

�To drive distribution utilities to go for planned procurement of

electricity not to rely upon over-drawl from the grid for meeting their

consumer demands.

�To enforce strict volume limits on over drawl / under drawl and over-

injection/under-injection irrespective of the grid frequency.

13

14

49.70 49.75 49.80 49.85 49.90 49.95 50.00 50.05 50.10

8.24 6.99 5.94 4.90 3.86 2.82 1.78 0.00 0.00

Under drawl / overinjection

Penalty @ 1.78 perKWh

No over drawl isallowed.

Overdrawl@ 16.48 Rs / KWh

i.e. 100% additionalcharge of Freq 49.70

Hz

Frequency range

Rate in Rs per KWh

Under drawls by the buyer / Over injcetion by seller in a time block in excess of 12%of schedule or 150 MW, shall be zero”.

If 12% of drawl schedule is more than 150 MW, thenadditional charges is as below:�OD in range (150 to 200 MW) 20% additional charges.�OD in range (200 to 250 MW) 40% additional charges.�OD more than 250 MW , 100 % additional charge

If 12% of drawl schedule is less than 150 MW, thenadditional charges is as below:�OD in range (12% to 15%) 20% additional charges.�OD in range (15% to 20%) 40% additional charges.�OD more than 20%, 100 % additional charge

Sustain deviation from schedule in one direction (+/-) of entity, entity shallhave to make sign change at least once after every 12 time block.

Statutory framework – Tariff mechanism for ISTS(Point of connection charges regulation 2010)

3. Sharing of Inter State Transmission Charges and Losses regulation:(Hon’ble CERC order No. L-1/44/2010-CERC Dated: 15th June 2010)

Principles for sharing ISTS charges and losses.� Based on the Yearly Transmission Charges of ISTS Transmission Licensees and

transmission losses in the ISTS network, the Implementing Agency shall compute thePoint of Connection charges and Loss Allocation Factors for all Designated ISTScustomer

(a) Using load-flow based methods; and(b) based on the Point of Connection Charging method.

This methodology sensitive to distance, direction and usage of network.Charges for LTA/MTOA : Rs/MW/MonthCharges for STOA : Rs/MW/Hour

Role of Implementing Agency: (NLDC)� Collection the Basic Network data pertaining to the network elements.� The generation and load at the various network nodes� Responsibility to run AC load flows using the basic Network, nodal generation and

nodal demand to ensure Load Generation balance is entrusted to IA.

The CTU shall be responsible for raising the transmission bills, collection anddisbursement of transmission charges to ISTS transmission licensees.

Statutory framework – Open Access – Short Term4. Open Access in inter-State Transmission) Regulations:

(Hon’ble CERC order No.L-7/105(121)/2007-CERC Dated 25th January, 2008)� “Short-term open access” means open access for a period up to one (1)

month at one time.� “Bilateral transaction” means a transaction for exchange of energy (MWh)

between a specified buyer and a specified seller, directly or through a tradinglicensee or discovered at power exchange through anonymous bidding, from aspecified point of injection to a specified point of drawl for a fixed or varyingquantum of power (MW) for any time period during a month.

� “collective transaction” means a set of transactions discovered in powerexchange through anonymous, simultaneous competitive bidding by buyersand sellers;

Eligibility for allowing STOA:The surplus capacity available on the ISTS after use by the long-term

customer and the medium-term customer, by virtue of-(a) Inherent design margins;(b)Margins available due to variation in power flows;(c)Margins available due to in-built spare transmission capacity

created to cater to future load growth or generation addition.

Statutory framework – Open Access – Short Term4. Open Access in inter-State Transmission) Regulations:

Nodal Agencies:�NLDC: For collective transections�RLDC: For bilateral transections of the region where point of drawal ofelectricity is situated.�SLDC: For intra state bilateral transections.

� Wherever the proposed bilateral transaction has a State utility or an intra-State entity as a buyer or a seller, concurrence of the SLDC is required.

� When a State utility or an intra-State entity proposes to participate intrading through a power exchange, it shall obtain a “no objection” or aprior standing clearance from the SLDC.

Statutory framework5. Renewable Regulatory Fund (RRF) regulation:

(Hon’ble CERC order No. L-1/18/2010-CERC Date of Order: 18-2-2011)

Applicable to:1.Wind farms with collective capacity of 10 MW and above connected at 33 KV leveland above.2.The Solar generating plants with capacity of 5 MW and above connected at 33 KVlevel and above.

The RRF shall be maintained and operated by the NLDC

�The wind generators shall be responsible for forecasting their generation uptoan accuracy of 70%. For actual generation within +/- 30% of the schedule, no UIwould be payable/receivable.�A maximum generation of 150% of the schedule only, would be allowed in atime block, for injection by wind, from the grid security point of view.�The schedule of solar generation shall be given by the generator based onavailability of the generator, weather forecasting, solar insolation, season andnormal solar generation curve and shall be vetted by the RLDC. If RLDC is of theopinion that the schedule is not realistic, it may ask the solar generator to modifythe schedule.

�No UI charges payable/receivable by Solar Generator 18

Statutory framework6. Congestion Management:

(Hon’ble CERC order No.L-7/139(159)/2008 Date of order: 22.4.2013)

Corridor shall be considered congested if:� Grid voltage in the important nodes downstream/ upstream of the

corridor is beyond the operating range specified in the IEGC and/or� The real time power flow along a corridor is such that n-1 criteria may

not be satisfied.� One or more transmission lines in the corridor are loaded beyond the

normal limit specified in CEA Manual on Transmission PlanningCriteria.

Congestion charge would be levied for

a) Over drawal or under-injection in the importing control area and

b) Under drawal or over-injection in the exporting control area.

It is also become applicable for an intra-regional corridor of one region.

TYPICAL SCADA SYSTEM

SCADAH/W &

S/WMEDIA

C TXO RXM EM QN P

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C TXO RxM EM QN P

T

R

T

U

T PR AA NN ES LDUCER

C & R

PANEL

CONTROLCENTRE SUBSTATION / GEN STATION

COMMNMEDIA

FIELD UNIT

Grid Operation Technology - Today

Load Despatching Facilities in India

SLDC GJ M

SRLDC

NLDC Main

NRLDC

Sub LDCJambuva

Sub LDCJetpur

→ PG FO Comn→ VSAT Comm

Sub LDCGandhinagar

NLDC Backup

WRLDC M ERLDC NERLDC

SLDC GJ B

10 Sec

2 Sec

2 Sec

20 Sec

New DelhiKatwariasarai

KalcuttaGolf Course Road

2014 October

RTU C RTU X

WRLDC B

2008 August

Tools for managingsystem operation:EMS package ofSCADA:�PNA�NSP�DDC�SDF

SLDC Control Centre

22

HMI (Work Station)

Application server

LAN

23

SOFTWARE REPRESENTATION OF REAL TIME HADWAREPOSITION at SLDC

10/100 MBPS HUB

10/100 MBPS HUB

ROUTER(2)

MUX(2)

OFC WIDEBANDCOMMUNICATION

OFC WIDEBANDCOMMUNICATION

RLDC

Sub-LDC

24

SCADA at Sub-LDC

SOFTWARE REPRESENTATION OF REAL TIMEHARDWARE POSITION WITH SCADA SYSTEM at Sub-LDC

26

Remote Terminal Unit at Field Level

Grid Operation – Todaywith Present SCADA

� MW, MVAR,Voltage, Frequency parameter reporting to control

center.

� No Time stamped data.

� State Estimator for load flow study.

� It is solution of Non-Linear equation.

� Best estimation of state of system known to operator.

� Limitation particularly with large complex system.

� Good for visualization but limited Decision making tools.

� slow data reporting time

� Steady state operation.

Internal Fire-wall

External Fire-wall

Work-station DTS Server

GPSVPS Work-station SCADA/EMS server

ICCP server F/wRouter

PrinterISRServer

NMSServer

Web-server

F/w RouterRouterRemote-VDU

Data ReplicaServer CMC

DDSServerF/w Router

Work-station

Internet

External DMZ

Internal DMZ

ICCPLAN

SCADALAN

Data LAN

OFFLINELAN

DTSLAN

RLDC/BackupSLDC/Sub-LDC

Corporate Network

CMC : Centralized Monitoring ConsoleISR : Information Storage and RetrievalNMS : Network Management ServerDDS: Database Development ServerDMZ: Demelitarized Zone

Grid Operation Technology - Tomorrow

Internal Fire-wall

External Fire-wall

GPS

VPS Work-stationSCADA/EMSserver

ICCP server F/wRouter

PrinterISRServer

NMSServer

Web-server

F/w RouterRouterRemote-VDU

Data ReplicaServer CMC

DDSServerF/w Router

Work-station

Internet

ExternalDMZ

Internal DMZ

ICCP LAN

SCADA LAN

Data LAN

OFFLINE LAN

RLDC/SLDC/Sub-LDC

Corporate Network

RTU IEC 60870-5-101 RTU IEC 60870-5-104

Data acquisitionLAN

Network Architecture for GETCO Backup Control Center Sub-LDC

30

Additional Features in New SCADA

Existing SCADA UpcomingSCADA

Remarks

Display 4 30

Trend Trend With 4points

New Featurewith 16 points

EMS Package Concurrent Access 1 4

Outage Scheduler Not Available New Feature

Transient Stability Not Available New Feature

Transmission /Corridor CapabilityMonitoring

Not Available New Feature

Web-interface Not Available New Feature

Event Based Email-SMS Not Available New Feature

31

Conti…..Features

Existing Upcoming Remarks

LANCopper PairCAT-6

Fiber No limitation ofBandwidth

Back up control center Not Available Available

Redundancy in Crossconnectivity betweenALDCs

Not Available Available Through BackUpSLDC

VPS system Bulb illuminated LED based 1)LessConsumption andlonger life2)Portableinterface

Firewall Not available Available

Intrusion Detection andPrevention System

Not Available Available Added Security

Video Conferencingfacility

Not Available New Features At SLDC &Backup SLDC.

32

BENEFIT TO THE SYSTEM OPERATOR:1)More User Friendly and Better GUI (3d trending)

2)More Number of Points for a Single Trend

3)More Number of Concurrent Displays

4) WEB Enabled interface - Visibility access from any where

5) Event Based SMS facility

SYSTEM BENEFIT:

1)Integration with WAMS/PMU

2)Integration with Renewable Energy Control Center

3) Fire wall provides better cyber security

New SCADA Highlights

Need for New System

� Time stamped data required for complex system.

� System stress depend upon Angular difference of

adjacent buses.

� Fast reporting of data require.

� Real time Angular measurement.

� Dynamic performance of system required.

� Decision making tools for system operator.

� Dynamic operation.

Solution is PMU & WAMS for grid operation

Grid Operation Technology

34

Today Tomorrow

Grid Operation technology – TomorrowPhasor Measurement Unit (PMU)

� PMU gives Phasor, voltage & current with its angular position.

� It is useful for system stress.

� Fast reporting rate 10,25,50 samples per cycle.

� It also gives frequency and rate of change of frequency.

� It is useful for Generation stability.

� PMU takes current and bus PT as input where it has placed.

� PMU send data precisely and time synchronized.

� It offers dynamic visibility of system behavior.

� Direct Angle measurement gives solution of linear equation.

� Intelligent decision making tools can be made for dynamic system

operation work.

Significance of Angle Difference on Power flow

PMU & WAMS

37

PMU Architecture

Sinusoidal representation of AC circuit

Two characteristics Magnitude and Angle

AC circuits Wave form and Phasorrepresentation

Phasor representation

In AC circuit, power flows from larger phaseAngle to smaller phase Angle.

Wide Area Monitoring System (WAMS)

� WAMS designed with PMU placed at different locations.

� All PMU data reporting to control center with time

synchronized.

� It gives information of phasor of different location at a time.

� Fast, time synchronized data enable a better indication of

grid stress.

� It can be used to trigger corrective actions to maintain

reliability.

� Improve situational awareness for the operator of the large

complex power system through the use of effective

visualization tools.

Wide Area Monitoring System (WAMS)GETCO Plan

� GETCO designed WAMS for system operation with a vision to have full

fledged WAMS in near future in phased manner.

� 25 Nos. location for PMU placement in first phase.

� Advanced MPLS-Communication between PMU to control center, SLDC.

� PMU will be given all current and Bus voltage as input where it has

placed.

� Multiple PMU used at many stations.

� PMU location decided on strategic technical importance.

� In direct observability characteristics will be used for more penetration

level.

� In future with more PMU placement full fledged WAMS for Gujarat system

operation work.

PMU1.....n

switch Router switchRouter

PMU1.....n

m

m

Existing LANColourprinter

Workstationconsole-1

Workstationconsole-2

Proposed Architecture of WAMS:

PDC-1 PDC-2

DataHistorianserver-1

DataHistorianserver-2

Router cum firewall

Router cum firewall

MPLS-Communication

Other LDC

Wide Area Monitoring System (WAMS)GETCO plan

� WAMS will improve situational awareness of operator with better real timevisualization..

� Voltage, current with its Angular position enable to know system stress inreal time.

� frequency and rate of change of frequency enable to know effect ofswitching action.

� Angular difference between two station and Grid as a whole enableoperator to know system capability in real time with changing scenario.

� It is planned to develop following Intelligent Analytics tool from PMU datafor system operation.

� On line oscillation stability mode identification.� Hybrid state estimator� Dynamic security Analysis (DSA) with voltage stability.

Development of Analytics

Following are some Analytics that can be developed from

PMU data

� Hybrid (Linear) state estimator.

�On line oscillation stability.

�Dynamic Security Assessment.

�Voltage Stability Analysis.

�Frequency Stability Analysis.

�Vulnerability Analysis of relay for Zone-3 blocking.

�Calibration of CVT/CT

�Transient stability Analysis.

Analytics software for system operation

On line oscillation stability mode identification.

� software will find oscillation mode

� Inter- area oscillation will be observed.

�Better damping means system is strong and capable for

contingency if any arise in future.

�Important for planning to find weak area.

�Effect of switching action and damping equipment can be

ascertain.

�Index for system strength well in advance for operator.

�One more parameter for outage management.

Visualization of Oscillation mode

47

Yellow Light Implying Dampingbelow Alert Levels (i.e. 5%)

Red Light Implying Dampingbelow Alarm Levels (i.e. 3%)

Dial Chart for Damping factor

Analytics software for system operation

Hybrid state Estimator�State estimator use PMU data and remaining data from SCADA

measurement

�Improve state estimation as PMU gives actual Angle measurement

precisely

�It will work as state measurement of system, solution of linear equation

when sufficient PMU data available.

�Useful to find safe loading of each equipment dynamically with

changing system scenario.

�optimization of resources with confident.

�Useful for planning of Transmission infrastructure based on system

behavior in real time different scenario.

GUI for Voltage Visualization

49

Analytics software for system operation

Dynamic Security Assessment with voltage stability.�Perform security assessment of system on predefined time interval.

�suggest possible remedial measures to operators.

�Path towards on line Transient stability

�It will show voltage limit of area, zone as defined.

�Intelligent tool for operator to know system behavior dynamically and

remedial action against possible contingency.

� It will make operator more intelligent to maintain system in secure

status and alarm in advance for possible contingency.

Integration with SCADA

Integration with SCADA

� Existing EMS data can be used for PMU applications.

� Full observability of Grid from PMU data can be achieved

in phased manner.

� Short term Analytics uses EMS data.

� Model validation and Hybrid state estimator are example

of SCADA Integration.

� Hybrid state Estimator uses PMU data and SCADA EMS

data giving more accuracy then conventional.

1. To ensure load – Generation balance in order to maintain systemfrequency within permissible band i.e. (49.90 Hz to 50.10 Hz):

a. Long term Planning:

� Annual planning of State & Private Sector Unit outages is being done to

ensure adequate availability to meet peak demand of every month.

� To keeping 10 to 15% margin for forced outages.

� Seasonal variation of renewables is taken into account.

� Seasonal effects is considered

� Outages of evacuation lines along with planned shutdown of units.

Grid Operation

53

b. Short term Planning:

� Planned shutdown of Units is reviewed.

� If any need arises, all generators are informed to squeeze their unit

outages.

� Finalize Monthly line / EHV elements outage schedule to ensure maximum

availability during peak hours.

c. Day a head planning:

� Generation availability from all the generators for next day.

� SLDC receives data of load forecast from Discoms.

� Unit outage request up to 16:00 Hrs for next day are being taken in to

account.

Considering all above, system operations are being planned.

54

2. To operate power system such a way that it should remain inStable State :Stable state means :

� System variables are in the normal range.� No equipment is being overloaded.� System is able to withstand a contingency without violating any of

the constraints.Actions are being planed to operate system in Stable State:

� Rescheduling of generation� Deferment of elements outages� Switching operations of reactors and capacitor bank in order to control

voltages at important node.� Close monitoring of weather parameters.� Formulation & Review of defense mechanism

SPS at strategic locations.Review of load connected under Df/Dt & UFR relays.Formulation of islanding scheme.

Grid Operation

55

Initiatives for better Power System Operation

� Keen interest to facilitate outages for construction of new EHV lines and

for R & M work of EHV lines.

� Proactive actions to facilitate outages of important elements

� SLDC has initiated RE desk to accommodate real time weather data of

the State and forecast from the various reliable sources / tools and

prepare anticipated variation for wind / Solar generation as well as load.

� Black start mock drill at regular interval:

� SOCC meetings at regular interval

� keen interest to relieve congestion in the network by proposing

worthwhile changes in network topology and getting them implemented

through the concerned agencies.56

Initiatives for better Power System Operation� Data visualization at all control centres & also accessing reliable data of

renewable energy generation in real time

� Adoption of prevailing latest technology in Monitoring system (WAMS /

SCADA), IT (Software development) and in Communication (AMR solution /

Data acquisition using radio link, GSM etc.

� Continuous improvement of web-site.

57

Defense Mechanisms

Any type of Grid Disturbance (Major or Minor) isdetrimental for Power System and badly affects theSociety and Economy.

•Properly planned defense mechanisms helps in

� Prevention of any type of grid disturbance.

� Minimizing the damages due to grid disturbances

� Faster Restoration of System.

•Based on the Root Cause Analysis of Past Grid Incidents / Disturbances,

Preventive, Corrective and Restorative Action Plans have been developed

to handle any contingency

58

Defense MechanismsPreventive Action Plans:

�Development of Ring Main System for MetroCities

�Islanding Schemes

�System Protection Schemes (RAS)�Conventional Protection Schemes

�Offline System Studies

�Reactive Power Management

�Special Switching Arrangements

�Power System Visualization

�Phase Angle Monitoring (PMU)

�Workshops & Seminar

�Training on Simulator

�Mock Trial of Generators / Transmission

System

�Information Management System

Corrective Action Plans:

�Weather Monitoring

�Revision in Protection Setting like

blocking of line tripping on Over current

etc.

Special Protection Scheme

• It is designed to detect predetermined system conditions and

automatically take corrective actions, other than the isolation of faulted

components, to meet system performance requirements or to limit the

impact of: two or more elements removed, an extreme event, or

Cascading.

• Such schemes are designed to maintain:

� System Stability

� Acceptable System Voltages,

� Acceptable Power flows, or to address other reliability concerns.

Hence, SPS provides the required stabilizing force necessary topreserve the system stability

The general characteristics of SPS are:

� Normally sleeping systems, Operate infrequently

� Control actions taken is predetermined

� Can be armed or disarmed depending upon system conditions

� Can comprise a large number of coordinated actions, in a cascaded

manner

All Special Protection Schemes consists of three main parts:

1.Input:

Level of physical magnitudes / Status of circuits breakers

2.Decision making system : To initiate some actions based on inputs

3. Output

Generator tripping, Fast valve opening, Runback Scheme or load

shedding.

Special Protection Scheme in Gujarat Power System1. SPS at APL complex to restrict power flow within limits in AC network:(Earlier)

Stage-1

Stage-2

Stage-3

Setting(Current/MW)

Time DelaySetting

(Current/MW)Time Delay

Stage-1 715 A 10 sec 715 A 10 sec

Stage-2 650 MW 1.5 sec 750 MW 1.5 sec

Stage-3 750 MW 4 sec 800 MW 4 sec

Action

Tripping of Unit-3 or Unit-4 to reducegeneration by 330 MW

Tripping of any one unit among Unit-5 to Unit-9 to reduce generation by 660 MW

Alarm

600 MW 1.5 sec Back down of generation from Unit-7-8-9

700 MW 4 sec

715 A 10 sec Alarm

Phase-2 Special Protection Scheme Settings

Setting (Current/MW) Time Delay Action400kV Mundra-Versana & Mundra-Hadala Circuit

Tripping of Unit-3 or Unit-4 as per selection

400kV Mundra-Sami Circuit-1&2

Group 1 (Both Line in service

without FSC)

Group 2 (Single Line in service

without FSC)

Group 3 (Both Line in servicewith FSC)

Group 4 (Single Line in servicewith FSC)

APL-DEHGAM BOTH LINE LOAD FLOW MORE THAN 700 MW THENGENERATION

APL GENERATION 1900CGPL GENERATION 2800EPGL GENERATION 1000

727 MW FLOW ONE LINE TRIP3OOMW GEN

LOSS500 MW GEN

LOSSAPL DEHGAM 727 964 873 717APL-HADALA 321 464 400 300HADALA-CHORNIA 570 700 640 550

APL-DEHGAM BOTH LINE LOAD FLOW LESS THAN 700MW THENGENERATION

APL GENERATION 1900CGPL GENERATION 2800EPGL GENERATION 500

LESS THAN 700MW ONE LINE TRIP

3OO MW GENLOSS

500 MW GENLOSS

APL DEHGAM 640 851 758 601APL-HADALA 368 494 430 332HADALA-CHORNIA 414 530 473 380

As on today,

Stage-1

Stage-2

Stage-3

Setting(Current/MW)

Time DelaySetting

(Current/MW)Time Delay

Stage-1 715 A 10 sec 715 A 10 sec

Stage-2 850 MW 1.5 secGreater than 1000

MW1.5 sec

Stage-3Greater than

700 MW & lessthan 800

1.5 secGreater than 850MW & less than

1000 MW1.5 sec

Stage-4Greater than

650 MWwithin 15 sec.

Greater than 750MW

within 15 sec afterStage -2 or Stage-3

operation

Tripping of any one unit formAPL No. 3 or 4.

200 to 300 MW generationreduction

400kV Mundra-Versana & Mundra-Hadala CircuitSetting (Current/MW) Time Delay Action

715 A

400kV Mundra-Sami Circuit-1&2 and Sami -Dehgam line 1 & 2

10 sec Alarm

Action

4.0 SecGeneration backing down @200 MW from Unit No. 3, 4, 5or 6.

4.0 Sec

Tripping of Unit-3 or Unit-4 asper selection ( If unit No. 3 isselected for 400 KV Mundra-Sami-Dehgam route then UnitNo. 4 is selected for thissetting)

Alarm

> 600 MW with availability ofany one or both 400 KV APL-

Sami-Dehgam line.

Group 3 (Both Line in service with FSC)

Group 4 (Single Line in service with FSC)

Group 1 (Both Line in service

without FSC)

Group 2 (Single Line in service

without FSC)

Tripping of any one unit formAPL No. 5 or 6.

> 600 MW + Non availability ofboth APL - Sami or Sami -

Dehgam line

SPS at CGPL, Mundra

SPS at regional Level

To arrest rise in frequency:Automatic tripping of following units at high frequency (51.5 Hz) with time

delay of 30 Sec in case of islanding of WR from rest of NEW grid:

1. KSTPS-7 (500 MW)

2. VSTPS-7 (500 MW)

3. CGPL-10 (830 MW).

SPS for Gwalior – Agra interregional link:•An SPS was envisaged for ensuring backing down WR generation by 500

MW (VSTPS - 200 MW, KSTPS – 120 MW, CGPL - 180 MW) in case of

sudden reduction of NR import from WR on Bina-Gwalior-Agra link by 1500

MW.

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Limitation and Challenges• Manual Control over generation, load, Switching elements

• Management of RE variations.

• RGMO / FGMO – Poor response by the generator today.

• Generation and Load balancing - To manage limit of ± 150

MW at State periphery.

• Load diversity and Load forecasting

• Assessment of transfer capability of flow gate in real time.

• Dynamic reactive power compensation. – No contribution by

the generator (VAR absorption) – managed by opening of

EHV lines.

1. Demand variation (Un expected & Expected):Grid Operation Challenges

68

2. RE generation variation:

Grid Operation Challenges

69

Operational Complexity

No of days when variationbetween Maximum and

Minimum demand

No of days when variationbetween Maximum and

Minimum wind generation

Year >2000 MW >1500 MW >1000 MW2011-12 51 159 112012-13 104 259 602013-14 114 260 82

� Variation of 1000-1200 MW generation in a day from renewable sources& 2000 MW variation in demand in a day is quite common. Such variationin the system is persistent and is handled by continuously analysingweather related information, generation regulation, optimizing theoperation of lines, ICTs and shunt elements like capacitors and reactors.

� SLDC is managing such complexities by using advanced Power SystemTools, effective planning for outages of transmission elements andgenerating units, ensuring real time data for entire grid observation etc.

Opportunity for Research� Analytics for WAMS.

� Renewable energy forecasting.

� Load forecasting methodology.

� Load balancing and grid parameters

� VSC (Voltage Source Converter)

� PST (Phase Shifting Transformer)

� STATCOM locations

� ICT tap optimization.

� Effect of harmonics in power system

� Reactive Capability testing of generators

� PSS tuning in order to damp out low frequency oscillation.

� Optimization of governor droop setting, testing of governor.

� Islanding Schemes & Special Protection Scheme designing. 71

Thank you