中性点非有效接地配电网故障选线新原理

Journal o f S out heast U n ivers it y（En g lish Ed ition）June 2 V o l.l6N o.l I S SN l 3—7985 NeW pri nc i P l e f or g r oun di n9Faul t Feeder de t ecti on

i n MV d i stri buti ons W i t h Neutr al l n e ff ecti ve l y Eart h ed

Zen g X ian g j un!Y i n X ian gg en Chen D eshu Zhan g Zhe

（D e p art m ent o f E lectrical Pow er En g i neeri n g，H uazhon g U n ivers it y o f S cience and T echno lo gy，W uhan43 74）Abstract：A new p ri nci p le f or g round i n g f ault f eeder detection based on ne g ative se C uence current vari-

ation and ener gy d iss i p ated i n t he f ault p o i nt is p resented.It has h i g h p recis ion i n bo t h iso lated s y ste m s

and resonance eart hed s y ste m s，even i n f ull-com p ensated s y ste m s.A nd it can be i nstalled at t he local

contro l un it o f f eeder i n d istri bution autom ation s y ste m s，such as fie ld ter m i nal un it（FTU）.T h is p ri n-

ci p le is verified b y EM T P s i m ulator and ex p eri m entation.

K e y words：p ro tective re la y i n g，f ault detection，d istri bution net w orks

M ost distri bution net w orks are iso lated s y ste m s or resonant eart hed neutral s y ste m s i n Chi na.T hese distri butions w it h neutral i neff ecti vel y g roundi n g can achieve si g nificant and econom ical i m p rove m ents i n saf et y and p ow er su pp l y C ualit y.U nf ort unatel y，g roundi n g f ault f eeder is difficult to be detected i n t hese distri butions［l-3］.

I n iso lated s y ste m s，t he zero se C uence current m a g nit ude o f g roundi n g f ault f eeder is t he su m o f ot her sound f eeds’，and t he zero se C uence current direction o f g roundi n g f ault f eeder is o pp osite to sound f eeders’.S o t he g roundi n g f ault f eeder can be detected b y com p ari n g f unda m ental zero se C uence current’s a m p lit udes or p hases i n t he iso lated s y ste m s.H ow ever，i n resonant eart hed s y ste m s，g roundi n g f ault current is ver y s m all.T he direction o f f unda m ental zero se C uence current is dist urbed b y t he com p ensation current due to Petersen-co il.S o t hat，it is i m p ossi ble to detect t he f ault f eeder b y com p ari n g f unda m ental zero se C uence current’s a m p lit udes and p hases.

O n t he ot her hand，Petersen-co il has hi g h i m p edance to hi g h order har m onics，so it has little eff ect to hi g h order har m onic current.T he g roundi n g f ault f eeder can be detected b y com p ari n g har m onic zero se C uence current’s a m p lit udes or p hases o f all f eeders i n resonant eart hed s y ste m s. Am on g hi g h order har m onic currents，t he fift h order har m onic current is t he best one to be used to detect t he g roundi n g f ault f eeder.M an y utilities have realized it［4］.But t he fift h order har m onic current is ver y s m all and it varies i n diff erent s y ste m s，so it o ften has p oor sensiti vit y i n p ractice.

I n Euro p e，m an y utilities i ncrease t he f ault current b y addi n g a resistor p arallel connection w it h com p ensation e C ui p m ent（Petersen-co il）［3］.T heref ore，when a si n g le-p hase directl y g roundi n g f ault or a low resistance-g roundi n g f ault occurs，t he w att m etric p rotection s y ste m s，which use t he p roduct o f zero se C uence vo lta g e m ulti p lied b y resi dual current as i n p ut，has a g ood result.H ow ever，when hi g h resistance g roundi n g f aults occur t his is no lon g er t he case［3］.I n order to detect hi g h resistance g roundi n g f ault f eeder，a ne w m et hod is p resented b y com p ari n g t he acti ve com p onent o f zero se C uence current［3］.But t he acti ve com p onent is ver y s m all i n m an y R ece ived l999-l -26.

!B orn i n l972，m ale，g raduate.

distri bution s y ste m s.T his rela y is also difficult to be realized i n p ractice.I n t his p a p er ，a ne W p ri nci p le f or g roundi n g f ault detection based on ne g ati ve se C uence current variation and ener gy dissi p ated i n t he f ault p o i nt is develo p ed.T his p ri nci p le is not aff ected b y t he m et hod o f s y ste m neutral g roundi n g .a nd it can be used i n t he detection o f bot h arc g roundi n g f ault and hi g h resistance g roundi n g f ault .

1The Pri nci p le and T echni I ue f or Fault D etection b y Ne g ative Se I uence c

urrent

on i n n ee is ve g h

13I f =

E A

3R f +Z 0+Z 1+Z 2

（1）

Where Z 0is t he zero se C uence i m p edance o f t he net W ork ；Z 1is t he p ositi ve se C uence i m p edance ；R f is f ault resistance ；Z 2is ne g ati ve se C uence i m p edance.

1Z 2=!n

i =1

1Z 2i +

1Z 2s （2）Where Z 2i is t he ne g ati ve se C uence i m p edance o f f eeder i （i nclude t he ne g ati ve se C uence

i m p edance o f loads ）

；Z 2s is t he ne g ati ve se C uence i m p edance o f s y ste m （source ）.T he ne g ati ve se C uence vo lta g e caused b y g roundi n g f ault is ：

U 2=-I 2Z 2=-E A Z 2

3R f +Z 0+Z 1+Z 2

（3）

T he ne g ati ve se C uence current i n t he sound f eeder i ：

I 2i =U 2Z 2i =-I 2Z 2Z 2i

（4）

T he ne g ati ve se C uence current i n f ault f eeder a ：

I 2a =I 2Z 2a -Z 2Z 2（）

a

（5）

M ost distri bution net W orks are radial s y ste m s i n Which t he f eeder is not connect W it h ot her source.S o t he load ’s ne g ati ve se C uence i m p edance o f an y one ’s f eeder is ver y hi g her t han t hat o f t he source.T heref ore ：

Z 2"Z 2s ，Z 2#Z 2i （6）

F rom E C s.（1）（4）（5）and （6），W e can deri ve

I 2a "I 2=13

I f ，I 2a $I 2i "0（7）T he ne g ati ve se C uence current o f g roundi n g f ault f eeder is about e C ual to one t hird o f f ault current ，and it is m uch lar g er t han t hat o f sound f eeder .S o t he g roundi n g f ault f eeder can be selected b y com p ari n g t he a m p lit ude o f ne g ati ve se C uence currents o f all f eeders Which are caused

b y g roundi n g f ault ［5］

.

T he ne g ati ve se C uence i m p edance o f source and t hat o f loads have som e characters o f

5

6N e W pri nci p le f or G roundi n g F ault F eeder D etection i n Mv D istri butions W it h …

i nductance ，i n Which t he p hase o f current la g s t hat o f vo lta g e.A nd t he i nducti ve com p onent is several ti m es o f t he resisti ve com p onent i n ne g ati ve se C uence current .T he vectors ’dia g ra m f or ne g ati ve se C uence current i n F i g .l is shoW ed i n F i g

.2.

m e ve or he ult so

Zhe

sound f eeder ’s ener gy f unction is al m ost e C ual to zero ，and it dro p s W it h ti m e dela y .theref ore ，

b y com p ari n g each f eeder ’s ener gy f unction to a t hresho ld （Which is p ositi ve ），if t he f or m er is

bi gg er ，t his f eeder is t he f ault f eeder .

I n hi g h resistance g roundi n g f aults ，t he ne g ati ve se C uence current variation is ver y loW.S o it is difficult to detect t he f ault f eeder b y t he ne g ati ve se C uence current variation.but t he vo lta g e o f f ault p hase is hi g h ，and ener gy dissi p ated i n t he f ault p o i nt still rises W it h ti m e dela y clearl y .S o t he f ault detection based on ener gy f unction has a g ood p erf or m ance i n hi g h resistance f ault （even above 10k !）.

I n order to clear u p t he eff ecti n g o f load unbalance ，variation o f ne g ati ve se C uence current is also used to detect t he g roundi n g f ault f eeder .If f ault detection rela y based on com p uter ，E C .（9）can be realized i n

! " 2

（10）Where is t he sa m p le val ue o f f ault p hase val ue ；3" 2 is t he tri p lication ne g ati ve se C uence current variation o f f eeder .

theref ore ，While zero se C uence vo lta g e exceeds its t hresho ld ，f ault detection is started.A fter calculati n g each f eeder ’s ener gy f unction b y E C .（9）and com p ari n g it to its t hresho l d ，t his f eeder Which ener gy exceed t his t hresho l d is t he f ault f eeder .W hen t here is no f ault f eeder to be detected ，it m a y be busbar g roundi n g f ault .

S om e g roundi n g f ault is t hrou g h arc g roundi n g .there is no ne g ati ve se C uence current after arc blackout .the arc has little aff ection to t he f ault detection based on ne g ati ve se C uence current .O n t he ot her hand ，ener gy is oscillati n g i ntensel y a m on g t he g roundi n g p o i nt ，t he f ault p hase ，and t he sound p hase ，duri n g arc g roundi n g f ault .there are lar g e ener gy dissi p ated i n t he f ault

ult i n arc

35），he =

1

para m eters o f f eeders f or s i m ulation

N a m e L1

L2L3L4（f ault ）A ttri bute O verhead E C uivalent

"

C ab le O verhead L en g t h ／k m

3010030203 0／#F 0.451.55.40.3d a m p i n g ／%4434Load ／

（k V ?A ）1200

10000

1200

1000

"E C uivalent m eans t he e C uivalent of o t her f eeders.

I n t ab.2，"3 21m

eans t he tri p licate ne g ati ve se C uence current variation o f L1（overhead f eeder ），"3 23m eans t he tri p licate ne g ati ve se C uence current variation o f L3（cable f eeder ），"3 24

m eans t he tri p licate ne g ati ve se C uence current variation o f L4（overhead f eeder W it h g roundi n g

f ault ）.S eries resistance m eans t he neutral eart hed m et hod o f petersen-co il series connect W it h resistance

g roundi n g .

7

6N e W pri nci p le f or G roundi n g F ault F eeder d etection i n MV d istri butions W it h …

Tab.2The resuit of simuiation

Fauit Neutrai!/%Uo/kV!3I21/A!3I23/A!3I24/A

Phase A Grounding

Fauit （R f=5"）Unground18.910.4200.43143.2 Resonance

018.710.0240.026 2.5

-1018.120.0490.050 5.1 Series

resistance

017.500.0520.054 5.3

-1017.320.0740.0737.4

Phase A

Grounding

Fauit

（R f=1000"）Unground7.070.1710.16917.0 Resonance

017.710.0200.021 2.2

-1015.010.0420.043 4.3 Series

resistance

015.200.0430.045 4.5

-1015.160.0620.065 6.3

From Tab.2，we can find that the negative seguence current variation of fauit feeder is about 100times to that of sound feeder in isoiated system，resonance earthed neutrai system or Petersen-coii series connect with a resistance earthed neutrai system.So the reiation of negative seguence current variation between sound feeder and fauit feeder is not affected by the method of system neutrai earthed.That is to say，in aii kinds of neutrai earthed，the protection based on negative seguence current variation can be used to detect grounding fauit feeder，and it has high precision.

In Fig.4，the first graph is arc grounding fauit，and the third，the fourth graph is

high

and Zhang Zhe

fauit feeder （feeder 4）rises ，but that of sound feeder

（feeder 1）is aimost eguai to zero.Therefore ，the function of energy can be used to detect high resistance fauit and arc grounding fauit.

Experimentation for grounding fauit detecting was passed in iaboratory.It has the simiiar resuit to EMTP simuiation.

4Conclusions

A new principie for grounding fauit feeder detection based on negative seguence current variation and energy dissipated in the fauit point is aiso presented.It aiso has many virtues ，such as ：

1）Negative seguence current variation is not affected by the method of system neutrai grounding.It has high precision in both isoiated systems and resonance systems ，even in fuii-compensated system.

2）The energy function to caicuiate energy dissipate in the fauit point can be used to detect high resistance grounding fauit and arc grounding fauit.

3）The fauit detection can be instaiied in iocai controi unit of feeder ，such as FTU.That is easiiy to satisfy the reguirement of distribution automation.

The principie for fauit detection based on negative seguence current variation is verified by EMTP simuiator.The research is now in progress on deveioping the fauit detection apparatus.

References

1I.N.Howeii ，and Irving Koiidny ，IEEE recommended practice for grounding of industrial and commercial power systems ，pubiished by the institute of eiectricai and eiectronics engineers ，New York ，pp.11-28

2Y.Fang ，Ouer-uoltage in distributions （In Chinese ）

，Eiectric Power Pubiication ，Beijing ，pp.28-42，19943 D.Griffei ，

and Y.Harmmand ，A new deai for safety and guaiity on MV networks ，IEEE Transactions on Power Deliu-ery ，voi.12，no.4，pp.1428-1433，1997

4X.J.Zeng ，

Y.Y.Yu ，Y.O.Zhou ，and O.W.Yang ，Distinguish between resonance and grounding fauit in distribution systems ，Power System Automation （In Chinese ）

，voi.22，no.8，pp.41-43，19985

M.H.Shi ，W.Yu ，and L.Wang ，A new type feeder earth fauit seiecting device for neutrai isoiated and arc suppression coii grounded systems ，Proceedings of Beijing Eiectric Power Internationai Conference on Transmission and Distribution Beijing ，pp.1-5，1997

中性点非有效接地配电网故障选线新原理

曾祥君

尹项根

陈德树

张

哲

（华中理工大学电力系，武汉430074）

摘要提出采用负序电流及故障点损耗能量进行故障选线的新原理，该原理不受中性点接地方

式的影响，适用于中性点不接地配电网、经消弧线圈接地配电网，甚至全补偿运行的配电网，该原理适合就地安装，便于在馈线就地控制终端单元（FTU ）上实现.原理已经仿真分析及模拟实验论证.关键词

继电保护，故障选线，配电网

中图法分类号

TM727，TM771

9

6New Principie for Grounding Fauit Feeder Detection in MV Distributions with …

中性点非有效接地配电网故障选线新原理

作者：曾祥君， 尹项根， 陈德树， 张哲

作者单位：华中理工大学电力系,武汉,430074

刊名：

东南大学学报（英文版）

英文刊名：JOURNAL OF SOUTHEAST UNIVERSITY(ENGLISH EDITION)

年，卷(期)：2000,16(1)

被引用次数：1次

参考文献(5条)

1.M H Shi;W Yu;L Wang,A new type feeder earth fault selecting device for neutral

isolated and arc suppression coil grounded systems, Proceedings of Beijing Electric Power International Conference on Transmission and Distribution Beijing 1997

2.X J Zeng;Y Y Yu;Y Q Zhou;Q W Yang Distinguish between resonance and grounding fault in distribution systems 1998(08)

3.D Griffel;Y Harmmand A new deal for safety and quality on MV networks[外文期刊]

1997(04)

4.Y Fang Over-voltage in distributions 1994

5.I N Howell;Irving Koildny IEEE recommended practice for grounding of industrial and commercial power systems, published by the institute of electrical and electronics engineers

引证文献(1条)

1.郭自刚配电网单相接地保护新方法及其信息融合实现研究[学位论文]硕士 2004

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