a novel arc-suppresion method for grounding fault in wind farm

8/12/2019 A Novel Arc-Suppresion Method for Grounding Fault in Wind Farm

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A Novel Arc-Suppression Method forGrounding Fault in Wind Farm

Li JianN -M mb rand Zeng Xian un M mb r IEEEZhao Zhenfeng N -M mb r

Zhan! YijieN -M mb r

h tract Neutral point non effectively grounded system isused in the wind farm with complex structure, high cost, widedistribution and higher capacitance current. This paper presentsan arc suppression method for the neutral non effectivegrounding system-voltage arc suppression method. A reactor isdirectly connected to the fault bus and ground. The voltage of thereactor is used to suppress the voltage of the fault phase, to make

sure it become much smaller than the amplitude of electricstrength recovery, undermine the arc renewed mechanism, andremove the arc grounding. Simulation result in the paper veri esthe validity and advantages of the method and it is not affectedby grounding current, eliminating the complex track andcompensation calculation. Arc suppression method is simple.Especially suitable for system with high capacity current suchas cables wind farms.

K yword :Capacitance current, Neutral point, Overvoltage,Wind farm, Arc suppression coil, ATP, Grounding arc foult, Arcmedium electric stre gth re overy, Neutra point ungroundedsystem, Reactor

I. NTRODUCTION

A t present, neutral-point non-effectively groundedmethod is used in the most of the 3-35kV distributiongird in wind farm in China[ 1. With the rapid development of the power system, main power wiring great changes have taken place, the amount of cables lines becomes larger andlarger, the percentage of cable lines in urban distribution gridbecomes higher and higher. Meantime, line-to-groundcapacitive current is also increasingly higher. In the wind farm, the transmission line is cable line, compared to overhead lineswith the same length, capacitive current of cable lines is 25 times higher, at the range of O-30A single-phase groundingcurrent where the single-phase intermittent arc grounding faulteasily happens. As a result, when single-phase arc groundingfau t occurs, the r u t p nt is d cu t o xti gu sh, ndproduces over-voltage which is up to 3.54.76 times higher than phase voltage, threatening the agile insulationequipment and causing damages to electrical equipment and

This work was suppor ed in par by Scientific Research Fund of HunanProvincial Education Depar ment 09K067 and 09CYII

Li Jian a graduate student of the School of Electrical& InformationEngineering, Changsha University of Science and Technology HunanProvince, 410076, P. R. China (e-mail : [email protected])

Zeng Xian un is with School of Electrical& Information Engineering,Changsha University of Science and Technology, Hunan Province, 410076, P.R. China (e-mail: [email protected])

97 9 7 /$IEEE

large-scale blackout[ 1. So it is necessary to do research toeliminate arc over-voltage.

This paper presents an new arc-suppression method forsingle-phase grounding arc fault. When single-phasegrounding arc fault occurs in the power system, a reactor isdirectly connected to the fault bus and ground. Forming theloop to suppress the voltage of the fault phase, reduce the fault

current and remove the arc grounding. Furthermore, beforee its, it e tends the working time length of reactor (3-5s ,according to the speci c situation), so as to ensure therecovery of the arc medium electric strength and clearingfaults.

II. HEORY OF ARC M DIUM ELECTR C STRENGTH RECOVERYTheory of arc medium electric strength recovery is

proposed in 957, as shown in Figure . No matter the arcsuppression occurs when it is high frequen y or pow rfrenquency becomes zero, if the recovery voltage peak Upvdetermined by the circuit inductance and circuit gradient less

than the amplitude of arc medium electric strength recoveryUds grounding arc reignition will not taken place.Conversely, if the amplitude of arc medium electric strengthrecovery less than the amplitude of fault voltages recoveryUrv, arc reignition will taken place, then forming intermittentarc grounding fault. E perimental results show that 3-35kVdistribution girds which neutral-point ungrounded, thecapacitive current Ic=5- 00A, When the recovery voltagepeak were 0.37Uxm(U is the Phase Voltage U m is thepeak of the Phase Voltage. The same below)and 0.23Uxm,grounding arc will not reignited.

u

The hreshol

2

Recovery voltagepeak Up. Medium e ec ric

fa vo ta se c_ove ry U

Fig the condition of arc-suppression


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A alysis of the theory ca be draw that whe si glephase arc grou di g fault occurs if we limit the voltage of the fault phase to a certai exte t, it ca remove the arcgrou di g. So the voltage arc-suppressio method is proposed,whe si gle-phase grou di g arc fault occurs, co trol theamplitude of fault voltages recovery less tha the amplitude ofarc medium electric stre gth recovery, grou di g arc will otreig ited

III. A N NEW VOLTAGE ARC SUPPRESS ON METHODAs show i gure 2 a d gure 3, By closi g switch i

the fault phase, a reactor is directly co ected to the fault busa d grou d. The voltage of the reactor is used to suppress thevoltage of the fault phase, to make sure it become muchsmaller tha the amplitude of electric stre gth recovery,u dermi e the arc re ewed mecha ism, a d remove the arcgrou di g. Furthermore, before exits, it exte ds the worki g

time le gth of reactor (3-5s, accordi g to the speci csituatio ), so as to e sure the recovery of the arc mediumelectric stre gth a d cleari g faults This system will ot o lye sure the si gle-phase grou di g arc fault ot expa di g to the phase to phase short circuit fault, but also avoidi g the trippi g, improvi g power supply reliability.

{;'

t-

.CIC

Fig 2 Zero-seque ce curre t circuit diagram a er the reactordevoti g

E Xc=a .U

.

L

Yr

3Fig 3 Equivale t circuit diagram

IV. MULAONThe paper builds the 0kV distributio etwork

simulatio model i the EMTP/A TP so ware, the simulatiochart is show i gure4. Substatio outgoi g li e used

equivale t circuit of I model. I the 4 outgoi g li e,

L ,L2,L4 is the overhead li e, L3 is the cable. I order tocarry o the simulatio of the si gle-phase grou di g faulteasily, li e L4 is divided i to two sectio s. The parameters ofoverhead li es are L= .042mH km,RO =0.27

km,CO=0.0035 F/km, the parameters of cables are

L=0.28mH km,RO =0.075 km,CO=0.43uF km, the le gthof the four li es are 30 km, OO km,30 km,20km.

I order to cleari g faults reliably i the maximumoperati g mode(whe a si gle phase grou di g foult occurs, the capacita ce curre t owi g through the foult poi t is themaximum), the reactor's i ducta ce a d the capacity should bedesig ed suitably. the i ducta ce is calculated as follows:

We ca see from the above i the OkV grid the recoveryvoltage peak should be


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15

,[kV

0

0

5

0

15

40.00 0 04 0.08 0 2 0. 6 [sJ 0 20

(file'1 i1 11 1.pI4;x vart) v: 02 4Fig 5 The arc voltage waveform of the single-phase grounding

arc fault in the neutral point ungrounded system150

-[AJ

0050

04 -

-50

00

15

-0 00 0 04 0 08 0 2 0 6 [sJ 0 20

file, [111111 I4x-va t)c 021 -L C2Fig 6 The fault current waveform of the single-phase

grounding arc fault in the neutral point ungrounded system1

- r -

500

- 000

3500

-5000

-6500

800 00

0.0

0.0- 8

0 1

0 1

[ S] .20

IJ, i111111.pl4; x-var v XX0215

Fig 7 The arc voltage waveform of the single-phase groundingarc fault in the voltage arc-suppression system

- A

5

0

5

0

0 5

O O I - - _ 0 00 0 04 0 0 8 0 2 0 6 s ] 0 20

(fileIJ\ M1 1 p a c: 0 4 L4C

Fig 8 The fault current waveform of the single-phasegrounding arc fault in the voltage arc-suppression system

V. ONCL SIONThrough the gure 7 and gure 8 simulated by

EMTP/ ATP, A reactor is directly connected to the fault busand ground to suppress the voltage of the fault phase canremove the arc grounding nearly 00%.Also it is not affectedby grounding current, eliminating the complex track andcompensation calculation. Compared with the neutral-pointgrounded via arc-suppression coil system, this method issimple, lower cost. Especially suitable for system with highcapacity current, such as wind farm. This method has greatresearch value, should be continued deeper study.

VI. EFERENCES[ ] X Liwei. The thoughts on the sing e ph se grounding f ult of kV

tr nsmitting line in wind power gener ting field. Ningxi ElectricPower,2009,(1:57-63[2] Y AO Hu nni n, CAO Meiyue. Reson nce Ground of Electric PowerSystems[M]. Bei ing: Chin Electric Power Press, 2000.[3] S N Ji ning. ZN05A Intelligent Type Integr ted Grounding ProtectionDevice. Gu ngdong Power Tr nsmission Technology, 2008 (3 28-31[4] WANG Y nsong, XIE Fei. Simul tion nd n lysis of single-ph se toground f ult in distribution networks. High Volt ge Engineering,2008,34(1 123-127.[5] SH Hongchun,XIAO B i.A tr nsient-b sed study on f ult line selectionfor single-ph se to ground f ults on distribution system. Autom tion ofElectric Power Systems,2002,26 (21 58-61[6] G Rongbin ,CA Xu ,CHEN H ikun , IN Zhi j i n ,GAO Wei guo.Modeling nd Simul ting of Single-ph se Arc Grounding F ult in Noneffective E r hed Networks. Autom tion of Electric PowerS s ms, 00 ,3 ( 13 6 6[7] ELKALASHYNI, LEHTONENM. Modeling nd experiment lverific tion of high imped nce rcing f ult in medium volt ge networks. IEEETr ns on Dielectrics nd Electric l Insul tion, 2007, 14(2 :375-383.

VII. IOGRAPHIES

Li Jian,w s bo in 1986.Sh ndong Province nd received his b chelordegree from Ch ngsh niversity of Science nd Technology, Chin in 2008He is now gr du te student t the School of Electric l& Inform tionEngineering, Ch ngsh niversity of Science nd Technology, Chin . Hisrese rch interest is power system protection nd control.


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Zeng Xian unreceived his bachelor degree from Hunan niversity in1993, his M.Sc. degree from Wuhan niversity in1996, and Ph.D degree from Huazhong niversityof Science & Technology in 2001. He thenworked as post-doctoral fellow in Xuji RelayCompany and the Hongkong Polytechnic

niversity. He is now a Professor and Dean of theSchool of lectrical& nformation ngineering,Changsha niversity of Science and Technology,China. His research interest is real-time computerapplication in power systems control andprotection

Zhao zh nf ngw s bo in 1981. he is a g d a e student a th School oflectrical& nformation ngineering, Changsha niversity of Science and

Technology, China. Her research interest is power system protection andcontrol.

Z ang YiJiewas bo in Changsha City , Hunan Province, China, onSeptember7 1985. She received the B.Sc. degree in engineering degree fromthe Changsha inversity of Science and Technology, Hunan, China, in2008 ,where he is currently pursuing the M.Tech. degree in electricalengineering.Her interests include smart grid and power systems protection

a novel arc-suppresion method for grounding fault in wind farm

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