Transient Analysis of Shunt Reactor Switching

8/8/2019 Transient Analysis of Shunt Reactor Switching

1/4

1

Abstract This paper presented the study of the transientphenomena originating from the shunt reactor energizing andde-energizing on the IEEE 14 bus transmission systems. Theseshunt reactor were installed in the load busbar to present thedifferences between solidly grounded and ungrounded banks.The TRV of Shunt Reactor Bank de-energization is worst forungrounded reactor bank. The shunt reactors must be to removeunder full-load conditions to improve the line loadability.

Simulations were made using the software program ATP/EMTP.

Index Terms Shunt reactor, Transient Recovery voltage(TRV), Switching operations, ATP/EMTP.

I. INTRODUCTION

nductors and capacitors are used on substation busbars,medium-length and long transmission lines to increase line

loadability and to maintain voltages near rated values. A highvoltage reactor is relatively frequently switched, during theperiods of the system operations with low loads it is energizedand with the rise of load it is de-energized again. Theinductors absorb reactive power and reduce overvoltagesduring light load conditions, also reduce transientovervoltages due to switching and lighting surges [1, 4]. Theshunt reactors can reduce line loadability if they are notremoved under full-load conditions. During the energization,high unsymmetrical currents can occur. At de-energization, atransient recovery voltage occurs in the breaker contacts withconsiderable magnitude [10].

The switching overvoltage can be dangerous for theequipment if their peak value exceeds the rated switchingimpulse withstand voltage of the equipment [6]. It is veryimportant to know the level of dielectric stress that occursduring operation in the system in order to avoid insulation

failures. Each interruption involves a complex interactionbetween the circuit breaker and the source and the reactor(load side) circuits. This interaction results in overvoltagesdependent on system parameters and characteristics of theload [7].

This work is the final project of INEL 6077: Surge Phenomena.Ariel Rivera-Coln is with the University of Puerto Rico, Mayagez

Campus, P.R. 00680 (e-mail: [email protected])Juan L.Vargas-Figueroa is with the University of Puerto Rico, Mayagez

Campus, P.R. 00680 (e-mail: [email protected])

Overvoltage relays may be used to disconnect the reactorsunder extreme high-voltage conditions [9]. However in thiscase, the associated transmission line must be de-energized atthe same time, otherwise disconnection of the reactors wouldonly further aggravate the overvoltage condition on thesystem.

The main objective of this paper is to report some transientphenomena caused by the energization and de-energization of

shunt reactors connected on wye grounded and ungrounded ina substation busbar.

II. POWER SYSTEM IEEE 14 BUS

System under study will be the IEEE 14 bus transmissionsystem presented in Fig. 1.

Fig. 1: IEEE 14 bus transmission system.

III. SHUNT REACTOR PARAMETERS

For the simulations in our study, the wye connected shuntreactor was grounded as is shown on figure 2, the followingparameters: R= 2 (M /phase), L= 0.9 (H/phase), r= 5( /phase) and C= 2.4 (nF/phase).

Transient Analysis of Shunt Reactor Switching(December 2005)

Ariel Rivera-Coln, Student Member, IEEE Juan L. Vargas-Figueroa, Student Member, IEEE

Lionel R. Orama-Exclusa, Member, IEEE

I


2/4

2

R

R R

L

L L

r

r r

C

C C

Fig. 2: Shunt reactor model.

The shunt reactors were connected for the simulation in the14 bus system at the load bus X0172 as shown in Fig. 3. Thesystem line to line voltage is 115kV.

Fig. 3: Reactor Bank connected at load bus X0172.

IV. SHUNT REACTOR ENERGIZATION TRANSIENT

During the closing, high unsymmetrical phase inrushcurrents with long time constant occurred [3]. Figure 4 presentthe inrush currents that pass through the contact breaker withwye shunt reactors. This is a very fast current transient thatcan be near of 10kA and the maximum transient overvoltagesare obtained from closing at an instant corresponding to peak voltage across breaker poles and their magnitude depends onthe values of the network parameters [5].

(file case14ATPasineliminarcargasPow er2.pl4; x-v ar t) c:X0075A-X0288A c:X0075B-X0288Bc:X0075C-X0288C

16.66 16.67 16.67 16.67 16.67 16.67 16.67[ms]-10.0

-7.5

-5.0

-2.5

0.0

2.5

5.0

7.5

10.0[kA]

Fig. 4: Breaker inrush current at the closing.

V. SHUNT REACTOR DE-ENERGIZATION TRANSIENT

When a circuit breaker interrupts shunt reactor currentseveral transient phenomena is be observed [7]. However notall of them occur necessarily during each interruption with

small inductive currents, the medium used for arcextinguishing will develop fast residual column resistance,and abrupt current interruption before its natural zero crossingmay occurs [2,3]. Release of energy stored in the reactorinductance will cause the electromagnetic transients that leadto switching overvoltages. These transients and theiroscillation modes are dependent by the load and the systemconfiguration where the reactor is installed.

Fig. 5 shows an increase in the bus voltage, from 87.927kVto 91.802kV, when the shunt reactor is de-energized with noload or light load.

Fig. 5: Shunt Reactor voltage effect.

Figure 6 shows the Transient Recovery Voltage that occursacross the contacts of the breaker when it is opening with theshunt reactor grounded. This TRV is the difference betweenthe voltage on the system busbar and the voltage in the


3/4

3

reactor. It depends on the current flowing thought of thebreaker, before the interruption took place.

dt di

LV L =

(f ile case14ATPasineliminarcargasPower.pl4; x- var t) c:X0077A-X0284A c:X0077B-X0284Bc:X0077C-X0284C

0 2 4 6 8 10 12 14 16[ms]-300

-200

-100

0

100

200

300

[A]

Fig. 6 represents the current of the breaker when it was opened.

When the current change abruptly Fig. 6, this differential of current is higher and consequently the voltage too.

Fig. 7 presents the TRV in the contacts of the breaker withthe shunt reactors ungrounded. This TRV has a damping ratiocaused by the internal resistances in the shunt reactors.

The rate of rise of recovery voltage (R.R.R.V.) is importantbecause it gives a measure of circuit severity from aswitchgear point of view. Following the American NationalStandard for the outdoor circuit breaker, the rating of the rateof rise of recovery voltage should not exceed 2.0 kV/s.

This peak voltage is around of 260KV that is 2.768988 puand the rise time is 0.1468 ms, then the R.R.R.V. of the studycase is equal to 1.77 kV/s which is in the range establishedby ANSI [8].

(file c ase14ATPasineliminarcargas.pl4; x-v ar t) v:X0077A-X0284A v:X0077B-X0284Bv:X0077C-X0284C

0 10 20 30 40 50[ms]-300

-200

-100

0

100

200[kV]

Fig. 7: TRV of wye shunt reactor ungrounded.

Fig. 8 represents the current in the breaker when the groundedreactor bank was opened.

(file cas e14ATPasineliminarcargasPower2.pl4; x -var t) c:X0176A-X0081A c:X0176B-X0081Bc:X0176C-X0081C

0 2 4 6 8 10 12 14 16[ms]-300

-200

-100

0

100

200

300

[A]

Fig. 8 represents the current of the breaker when it was opened.

Fig. 9 presents the TRV in the contacts of the breaker withthe shunt reactors grounded. This TRV has a damping ratio

like ungrounded.


0 10 20 30 40 50[ms]-200

-150

-100

-50

0

50

100

150

200[kV]

Breaker TRV

Fig. 9: TRV of wye shunt reactor solidly grounded.

The peak voltage of this transient is 173.14 kV that is1.843933 pu. This value of peak voltage is close to the 2.0 puthat is expected.

As mentioned before the amplitude of the voltage is 173.14kV and the rise time is 0.1385 ms, then the R.R.R.V. of thestudy case is equal to 1.25 kV/s which is in the rangeestablished by ANSI [8]. In this case, the TRV can beobserved that the voltage between the contacts of the breakerat the opening operation is smaller that with the shunt reactorungrounded.


4/4

4


8.5 8.6 8.7 8.8 8.9 9.0 9.1 9.2[ms]-180

-140

-100

-60

-20

20[kV]

Braker TRV (Z oom)

Fig. 10: Zoom of Fig. 9

Fig. 11 shows the system with light load at 91,866V in the busvoltage and decrease to 87,528V when the reactor bank isconnected, then the load is restored and it decrease to 84,134Vand is needed removed the reactor bank to increase the busvoltage.

Fig. 11: Load and Shunt Reactor Switching Response

VI. CONCLUSION

This paper study the transient phenomena that occur when ashunt reactor grounded and ungrounded are switching in theload busbar. The TRV of Shunt Reactor Bank de-energizationis worst for ungrounded reactor bank.

These switching operations of shunt reactor are relativelyfrequent on each day and primarily depend on power network loading. Then of several simulations with ATP/EMTP it isdemonstrated that the major difference using the shunt reactorgrounded is that the transient recovery voltage and theR.R.R.V. are less than ungrounded. The shunt reactors mustbe to remove under full-load conditions to improve the lineloadability.

VII. REFERENCES

[1] Ching-Yin Lee, Chang-Jhih Chen, Chao-Rong Chen,Yen-Feng Hsu " Comparison of Transient Phenomenawhen Switching Shunt Reactors on the Lines TwoTerminals and Station Busbar ," presented atPOWERCON 2004, Singapore, 21-24 November 2004.

[2] G. W. Chang, H. M. Huang, J.H. Lai, " Modeling SF6 Circuit Breaker for Shunt Reactor Switching Transient

Analysis ," presented at POWERCON 2004, Singapore,21-24 November 2004.

[3] I. Uglesic, S. Hutter, M. Krepela, B. Filipovic, F. Jakl"Transients Due to Switching of 400 kV Shunt Reactor "presented at International Conference on Power SystemsTransients, Ro de Janeiro, Brazil, June 24-28, 2001.

[4] J. D. Glover, M. S. Sarma, Power System Analysis and Design , Third Ed., 2002.

[5] C. D. Tsirekis, N. D. Hatziargyriou " Control of Shunt Capacitors and Shunt Reactors Energization Transients, "presented at International Conference on Power SystemsTransients, New Orleans, USA, 2003.

[6] B. Khodabakhchian, J. Mahseredjian, M.-R. Sehati, M.

Mir-Hosseini, " Potential Risk of Failures in Switching EHV Shunt Reactors in Some One-and-a-half Breaker Scheme Substations ," presented at InternationalConference on Power Systems Transients, New Orleans,USA, 2003.

[7] D. F. Peelo, E. M. Ruoss, " A New IEEE ApplicationGuide for Shunt Reactor Switching ," IEEE Transactionson Power Delivery, Vol. 11, No. 2, April 1996.

[8] American National Standard, AC High-Voltage CircuitBreakers Rated on a Symmetrical Current Basis-PreferredRatings and Related Required Capabilities. ANSI/IEEEC37.06-2000

[9] American National Standard, IEEE Guide for the

Protection of Shunt Reactors. ANSI/IEEE C37.109-1988[10] A. Greenwood, Electrical Transients in Power Systems,

Second Ed., 1991.

.

Documents

Transient Analysis of Shunt Reactor Switching