CN1482717A - Method for earthing and line selecting by using compensating electrified wire netting increment function - Google Patents

Abstract

A compensation electrified wire netting increment function earth connection wire selection method comprising, continually detecting electrified wire netting zero-sequence voltage, classifying earth connection phenomenon into two categories of permanent ground connection and transient ground connection, constituting an increment function, for permanent ground connection the increment function being a current increment function, for transient ground connection the increment function being an energy increment function, by searching grounding branch through the detecting increment function, the goal of distinguishing ground connection branch and non-ground connection branch can be achieved. The invention can function both for permanent ground connection and transient ground connection, and there is no dead zone with the earth connection distinguishability improved.

Description

Compensation network increment function earthing wire-selecting method

Technical field

The present invention relates to a kind of earthing wire-selecting method, specifically is a kind of compensation network increment function earthing wire-selecting method.Belong to technical field of electricity.

Background technology

In medium voltage distribution network (China is 6～66KV electric pressure electrical network), single phase ground fault accounts for more than 80% of total failare, improvement to single-phase earthing harm is extremely important, one of main improvement is the arc suppression coil compensation earth current to be installed and to be utilized line-selected earthing device to search the ground connection branch road fast at neutral point, fixes a breakdown.Electrical network single-phase earthing phenomenon complexity can be divided into permanent earth and transient state ground connection.Low-impedance earthed system, high resistance ground, change resistance ground connection and arcing ground etc. are arranged in the permanent earth.Transient state ground connection has instant earthing, intermittent ground arc ground connection etc.

Find by literature search, shine to wait in year on " electric power system resonance grounding " (2001) that people China Electric Power Publishing House publishes last the 151st～162 page and introduced a kind of residual flow method of addition, take place to search the ground connection branch road by detecting the variable quantity that changes each branch road zero-sequence current of arc suppression coil compensation electric current front and back after the ground connection.This method does not consider that the arc suppression coil compensation electric current changes the factor that causes residual voltage to change, and effect is bad during grounding through resistance, and grounding through resistance is usually judged by accident on the long transmission line.This method is not considered the influence of the factors such as imbalance, transformer error of electrical network before the ground connection yet in addition.Adopt this method to divide earth connection road and non-ground path by right area, and said method only work to the permanent earth phenomenon, inoperative to the transient state grounding phenomenon.Also find in the retrieval, people such as what Pentium are at " journal of Zhejiang university " 1998,32 (4): write articles " energy method small current earthing wire-selecting principle " on 451～457, this article is introduced the method that a kind of energy method detects transient state earth fault, the energy function of ground connection branch road is less than zero, and the energy function of non-ground connection branch road is greater than zero.Energy method is big and the dead band is arranged when high resistance ground takes place at the unbalanced power supply degree, and resolution is low when high resistance ground takes place.

Summary of the invention

The objective of the invention is to overcome above technical deficiency, a kind of compensation network increment function earthing wire-selecting method is proposed, make it by constructing the increment function that obviously to distinguish ground connection branch road and non-ground connection branch road, utilize this increment function right area to divide earth connection road and non-ground path, permanent earth and wise attitude grounding phenomenon are all worked, and do not have the dead band, improved ground connection resolution.

The present invention is achieved by the following technical solutions, the present invention is by continuous detecting electrical network residual voltage, amplitude situation of change according to residual voltage, grounding phenomenon is divided into two types of permanent earth and transient state ground connection, combine with modern arc extinction compensation technology, construct the characteristic quantity that obviously to distinguish ground connection branch road and non-ground connection branch road, be called increment function, at this increment function of permanent earth is the current increment function, at this increment function of transient state ground connection is the energy increment function, search the ground connection branch road by detecting increment function, thereby reach the purpose of distinguishing ground connection branch road and non-ground connection branch road.

Modern arc extinction compensation technology is divided into dual mode.A kind of is to give the mode bucking-out system.At arc suppression coil branch road serial or parallel connection damping resistance, increase the electrical network ratio of damping, make that series resonance over-voltage was less than 15%U when electrical network normally moved _Φ, so just can when electrical network normally moves, arc suppression coil be tuned to full compensation or approaching full compensating coefficient, wait for the generation of earth fault.After single-phase earthing occurring, the damping resistance short circuit is fallen or excise, thereby realize The optimal compensation.Another kind is the trailing type bucking-out system.When electrical network normally moves, strengthen and take off humorous degree, make arc suppression coil, behind electrical network generation single-phase earthing, adjust the arc suppression coil inductance, realize The optimal compensation to full compensating coefficient away from resonance point.As seen this dual mode all is after ground connection is taken place, and changes the impedance of arc suppression coil branch road.The one, the resistance (corresponding to giving mode) of change arc suppression coil branch road, another is the inductance (corresponding to trailing type) that changes the arc suppression coil branch road.

Below the inventive method is further described, particular content is as follows:

1, current increment function

At permanent earth, after taking place, ground connection regulates the inductance or the resistance of arc suppression coil branch road, utilize the residual voltage  of its forward and backward system of impedance variation ₀,  ₀', each branch road zero-sequence current And each branch road nature unsymmetrical current before the generation earth fault

With residual voltage  under the compensation network normality _0nom, construct a zero-sequence current increment function.This function expression is: $\mathrm{\Δ}{\stackrel{\·}{I}}_{0j}=({\stackrel{\·}{I}}_{0j}^{\′}-{\stackrel{\·}{I}}_{\mathrm{bp}0j})\frac{{\stackrel{\·}{U}}_0-{\stackrel{\·}{U}}_{0\mathrm{nom}}}{{\stackrel{\·}{U}}_0^{\′}-{\stackrel{\·}{U}}_{0\mathrm{nom}}}-({\stackrel{\·}{I}}_{0j}-{\stackrel{\·}{I}}_{\mathrm{bp}0j}),(j=\mathrm{1,2}\·\·\·m)$ This function can obviously be distinguished ground connection branch road and non-ground connection branch road.Ideally, the zero-sequence current increment function of non-ground connection branch road is zero.The zero-sequence current increment function of ground connection branch road is:

● corresponding to the trailing type bucking-out system $\mathrm{\Δ}{\stackrel{\·}{I}}_{0i}=-\frac{1}{3}\frac{{\stackrel{\·}{U}}_0}{U_{\mathrm{\Φ}}}\mathrm{j\Δ}{I}_L$ Wherein $\mathrm{\Δ}{I}_L=U_{\mathrm{\Φ}}(1/\mathrm{\ω}{L}^{\′}-1/\mathrm{\ωL})$ Be arc suppression coil compensation current change quantity under the rated voltage, its size is $\mathrm{\Δ}{I}_{0i}=\frac{1}{3}\frac{U_0}{U_{\mathrm{\Φ}}}\left|\mathrm{\Δ}{I}_L\right|=\frac{1}{3}{K}_0\left|{\mathrm{\ΔI}}_L\right|,$ Direction is: as Δ I _L＞0 o'clock, Lag behind  ₀90 °, as Δ I _L＜0 o'clock,

Be ahead of  ₀90 °, K ₀=U ₀/ U _ΦBe residual voltage percentage before the arc suppression coil reactance change.

● corresponding to giving the mode bucking-out system $\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{I}}_{0i}=\frac{1}{3}\frac{{\stackrel{\&CenterDot;}{U}}_0}{U_{\mathrm{\&Phi;}}}\mathrm{\&Delta;}{I}_R$ In the formula: $\mathrm{\&Delta;}{I}_R=-U_{\mathrm{\&Phi;}}/r_{\mathrm{zm}},$ Its size is $\mathrm{\&Delta;}{I}_{0i}=\frac{1}{3}\frac{U_0}{U_a}\left|\mathrm{\&Delta;}{I}_R\right|=\frac{1}{3}{K}_0\left|{\mathrm{\&Delta;I}}_R\right|,$ Direction With  ₀Oppositely, r _ZmBe damping resistance, K ₀=U ₀/ U _ΦBe residual voltage percentage before the damping resistance excision.So the play of declaring of trailing type bucking-out system ground connection branch road i is: i ∈ (k, Δ I _k＞Δ I _Jmax, the 90-ΔΦ _Max＜| Φ _k|＜90+ ΔΦ _Max) or: $i\&Element;(k,|\mathrm{\&Delta;}{I}_{0k}|=\underset{j=1}{\overset{m}{\max }}\left(\right|\mathrm{\&Delta;}{I}_j|,90-\mathrm{\&Delta;}{\mathrm{\&Phi;}}_{\max }<|{\mathrm{\&Phi;}}_k|<90+\mathrm{\&Delta;}{\mathrm{\&Phi;}}_{\max })$ Δ I wherein _JmaxBe the non-ground connection branch road zero sequence increment function maximum that causes owing to measure error, ΔΦ _MaxBe ground connection branch road zero-sequence current increment function and the  that causes owing to measure error ₀Phase difference departs from 90 ° maximum.Φ then _iThe symbol foundation Change direction and decide, to Δ I _LThe size principle of adjusting be: $\mathrm{\&Delta;}{I}_L>K_k\frac{3\mathrm{\&Delta;}{I}_{j\max }}{K_0},$ K _kBe safety factor.

The play of declaring of giving mode bucking-out system ground connection branch road i is:

I ∈ (j, Δ I _j＞Δ I _Jmax, the 180-ΔΦ _Max＜| Φ _j|＜180+ ΔΦ _Max) or: $i\&Element;(k,|\mathrm{\&Delta;}{I}_{0k}|=\underset{j=1}{\overset{m}{\max }}\left(\right|\mathrm{\&Delta;}{I}_j|,180-\mathrm{\&Delta;}{\mathrm{\&Phi;}}_{\max }<|{\mathrm{\&Phi;}}_k|<180+\mathrm{\&Delta;}{\mathrm{\&Phi;}}_{\max })$ Φ wherein _iSymbol for negative, promptly the direction of ground connection branch road increment function and residual voltage are reverse.Δ I _RThe principle of adjusting be: $\mathrm{\&Delta;}{I}_R>K_k\frac{3\mathrm{\&Delta;}{I}_{j\max }}{K_0},$ K _kBe safety factor.

2, the energy increment function is at transient state ground connection, and the energy increment function expression is: $\mathrm{\&Delta;}{S}_{0j}={\&Integral;}_0^T(u_0\left(\mathrm{\&tau;}\right)-u_{0\mathrm{nom}}\left(\mathrm{\&tau;}\right))(i_{0j}\left(\mathrm{\&tau;}\right)-i_{\mathrm{bp}0j}\left(\mathrm{\&tau;}\right))\mathrm{d\&tau;},(j=\mathrm{1,2}\&CenterDot;\&CenterDot;\&CenterDot;m),$ T is a power frequency period, establishes t=0 ground connection, u take place constantly _0nom(t) and i _Bp0j(t) for ground connection take place before (3T ,-2T) time period residual voltage and each branch road zero-sequence current instantaneous value, u ₀(t) and i _0j(t) be after the ground connection (0, T) time period residual voltage and each branch road zero-sequence current instantaneous value.This function can obviously be distinguished fault branch and non-fault branch.The size of fault branch energy increment function equals all non-fault branch increment function size sums in theory, and direction is opposite.As the reference direction that defines zero-sequence current is that then transient state ground connection branch road i route selection criterion is from the bus outflow: $i\&Element;(k,\mathrm{\&Delta;}{S}_{0k}<0,|{\mathrm{\&Delta;S}}_{0k}|=\underset{j=1}{\overset{m}{\max }}\left(\right|\mathrm{\&Delta;}{S}_{0j}|)$ Or i ∈ (k, Δ S _0k＜0, | Δ S _0k|＞Δ S _Zd) Δ S wherein _ZdBe setting value.

Compensation network increment function earthing wire-selecting method of the present invention is applied to the trailing type bucking-out system, gives the mode bucking-out system, and concrete steps are as follows:

● corresponding to the trailing type bucking-out system, method step is specific as follows:

When 1) electrical network normally moves, synchronous acquisition electrical network residual voltage and each branch road zero-sequence current, the storage data are handled the residual voltage data with DFT or FFT, obtain fundamental voltage amplitude U _0mon

2) compare residual voltage fundamental voltage amplitude U _0monWith setting value U _Zd, as greater than setting value, think that ground connection takes place, constantly t=0;

3) send the adjustment signal that makes arc suppression coil arrive the The optimal compensation state;

4) synchronous acquisition electrical network residual voltage and each branch road zero-sequence current, the storage data are analyzed the residual voltage data, obtain residual voltage amplitude U ₀, calculating K ₀=U ₀/ U _Φ

5) press ${\mathrm{\&Delta;I}}_L{>K}_k\frac{3\mathrm{\&Delta;}{I}_{j\max }}{K_0}$ Determine the regulated quantity of arc suppression coil, K _kGet number, Δ I greater than 1 _JmaxGet the minimum value that zero sequence current mutual inductor can accurately be measured;

6) by 5) adjustment amount provide arc suppression coil and adjust signal;

7) electrical network residual voltage and each branch road zero-sequence current after the adjustment of synchronous acquisition arc suppression coil, record data;

8) send the signal that arc suppression coil turns back to the The optimal compensation state;

9) processing 7) residual voltage data in the record data are judged earthing type; 10) if permanent earth handles 1) middle data of gathering, obtain each branch road zero-sequence current and electrical network residual voltage fundametal compoment

And  _0monHandle 4) in the data of gathering, obtain each branch road zero-sequence current and electrical network residual voltage fundametal compoment behind the ground compensation And  ₀, handle 7) in the data of gathering, obtain each branch road zero-sequence current and electrical network residual voltage fundametal compoment after the arc suppression coil adjustment And  ₀, calculate $\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{I}}_{0j}=({\stackrel{\&CenterDot;}{I}}_{0j}^{\&prime;}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{bp}0j})\frac{{\stackrel{\&CenterDot;}{U}}_0-{\stackrel{\&CenterDot;}{U}}_{0\mathrm{nom}}}{{\stackrel{\&CenterDot;}{U}}_0^{\&prime;}-{\stackrel{\&CenterDot;}{U}}_{0\mathrm{nom}}}-({\stackrel{\&CenterDot;}{I}}_{0j}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{bp}0j}),$ It is the ground connection branch road that peaked branch road is arranged: 11) if transient state ground connection gets 1) in the data of gathering obtain each branch road zero-sequence current and electrical network residual voltage instantaneous value i before the ground connection _Bp0jAnd u _0monOne group of sampled value, get 4) in the data data of gathering, obtain each branch road zero-sequence current of period 1 and electrical network residual voltage instantaneous value i after the ground connection _0jAnd u ₀One group of sampled value, calculate increment function with numerical integration $\mathrm{\&Delta;}{S}_{0j}={\&Integral;}_0^T(u_0\left(\mathrm{\&tau;}\right)-u_{0\mathrm{nom}}\left(\mathrm{\&tau;}\right))(i_{0j}\left(\mathrm{\&tau;}\right)-i_{\mathrm{bp}0j}\left(\mathrm{\&tau;}\right))\mathrm{d\&tau;},$ There is maximum person to be the ground connection branch road.

Corresponding to giving the mode bucking-out system, method step is specific as follows:

1) together corresponding to the step 1) in the trailing type bucking-out system method step;

2) together corresponding to the step 2 in the trailing type bucking-out system method step);

3) electrical network residual voltage and each branch road zero-sequence current after the synchronous acquisition ground connection, record data;

4) send excision damping resistance signal:

5) electrical network residual voltage and each branch road zero-sequence current behind the synchronous acquisition excision damping resistance, record data;

6) processing 5) residual voltage data in the record data are judged earthing type;

7) if permanent earth handles 1) middle data of gathering, obtain each branch road zero-sequence current and electrical network residual voltage fundametal compoment And  _0monHandle 3) middle data of gathering, obtain damping resistance excision each branch road zero-sequence current of back and electrical network residual voltage fundametal compoment And  ₀, handle 5) in the data of gathering, obtain each branch road zero-sequence current and electrical network residual voltage fundametal compoment after the arc suppression coil adjustment And  ₀', calculate $\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{I}}_{0j}=({\stackrel{\&CenterDot;}{I}}_{0j}^{\&prime;}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{bp}0j})\frac{{\stackrel{\&CenterDot;}{U}}_0-{\stackrel{\&CenterDot;}{U}}_{0\mathrm{nom}}}{{\stackrel{\&CenterDot;}{U}}_0^{\&prime;}-{\stackrel{\&CenterDot;}{U}}_{0\mathrm{nom}}}-({\stackrel{\&CenterDot;}{I}}_{0j}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{bp}0j}),$ It is the ground connection branch road that peaked branch road is arranged;

8) together corresponding to the step 11) in the trailing type bucking-out system method step;

The present invention has substantive distinguishing features and marked improvement, when stable state ground connection is taken place, the current increment function that the present invention passes through to be constructed not only can be eliminated unbalanced power supply, instrument transformer is asymmetric and the influence of transformer error, and eliminated residual voltage effectively and changed influence non-ground connection branch road, make that the current increment function of non-ground connection branch road is zero, it is big that the current increment function of ground connection branch road becomes, thereby both can obviously make a distinction.No matter be metallic earthing or high resistance ground, the increment function of ground connection branch road is all maximum.When transient state ground connection is taken place, the energy increment function that the present invention passes through to be constructed can be eliminated unbalanced power supply effectively, instrument transformer is asymmetric and the influence of transformer error, especially when ground connection be not to occur in ground connection phase voltage peak value, ground connection transient process situation hour.Adopt the energy increment function to improve ground connection resolution, and do not have the dead band.

Embodiment

Provide following examples in conjunction with the inventive method content:

1, judge the situation of trailing type compensation network generation permanent earth with the inventive method, specific as follows:

Certain 10KV compensation network has three branch roads, and the three-phase ground capacitance of article one branch road is 1uf, and the three-phase ground capacitance of second branch road is 4uf, and the three-phase ground capacitance of the 3rd branch road is 15uf, electrical network total ground capacitance C _∑=20uf, unbalanced earth fault capacitance current I _C=36.35A.Suppose that electrical network three is symmetrical, degree of unbalance is zero, electrical network ratio of damping d=5%.Adopt the trailing type bucking-out system, take off humorous degree υ=50% under the normality, zero sequence starting resistor U _0zd=30%U _Φ, U _ΦBe the electrical network phase voltage.

If article one R takes place in branch road a mutually _d=955.4 Ω permanence resistor earth faults, get the hang of 1: the residual voltage size is $U_0=\frac{U_{\mathrm{\&Phi;}}}{\sqrt{{(1+\mathrm{\&omega;}{C}_{\mathrm{\&Sigma;}}{R}_{d}d)}^2+{\left({\mathrm{\&omega;C}}_{\mathrm{\&Sigma;}}{R}_d\mathrm{\&upsi;}\right)}^2}}=30.6\%U_{\mathrm{\&Phi;}},$ This value is greater than starting resistor.The bucking-out system action gets the hang of 2: the full compensating coefficient of υ=0, this moment, residual voltage was U ' ₀=76.9%U _ΦAs regulating the overcompensation state of arc suppression coil to state 3: υ=-10% again, residual voltage is U " ₀=69.8%U _ΦFault branch zero-sequence current size formula is under each state: $I_0=\frac{I_C}{3}\frac{\sqrt{d^2+{\mathrm{\&upsi;}}^2}}{\sqrt{{(1+{\mathrm{\&omega;C}}_{\mathrm{\&Sigma;}}{R}_{d}d)}^2+{\left(\mathrm{\&omega;}{C}_{\mathrm{\&Sigma;}}{R}_d\mathrm{\&upsi;}\right)}^2}},$ Following table is for using the result of calculation of residual flow method of addition and current increment function method respectively.As seen, after No. 1 branch road ground connection, electrical network changes to state 2 from state 1, is that No. 1 branch road increment function is 1.85A with electric current increment function method result of calculation, and No. 2 and No. 3 is 0A.Can obviously distinguish No. 1 branch road is ground path.But with residual flow method of addition result of calculation is that No. 1 branch road increment is 1.39A, be for No. 2 1.15, No. 3 be 4.30A, No. 3 maximums but be not the ground connection branch road are so the residual flow method of addition is judged by accident.

Table 1 embodiment 1 result of calculation

Each branch current increment during Status Change	When state 1 arrives state 2 (A)			When state 2 arrives state 3 (A)
							Branch number	1	?2	?3	?1	?2	?3
Residual flow method of addition result of calculation	1.39	?1.15	?4.30	?0.48	?0.23	?0.86
							Current increment function method result of calculation	1.85	?0	?0	?0.93	?0	?0

2, judge the situation of giving mode compensation network generation permanent earth with the inventive method, specific as follows:

Electrical network gives the mode bucking-out system with embodiment 1 but adopt.Certain 10KV compensation network has three branch roads, and the three-phase ground capacitance of article one branch road is 1uf, and the three-phase ground capacitance of second branch road is 4uf, and the three-phase ground capacitance of the 3rd branch road is 15uf, electrical network total ground capacitance C _∑=20uf, unbalanced earth fault capacitance current I _C=36.35A.Suppose that electrical network three is symmetrical, degree of unbalance is zero, electrical network ratio of damping d=5%.The mode bucking-out system is given in employing, arc suppression coil branch road 3000 Ω damping resistances in parallel under the normality.Take off humorous degree υ=0, zero sequence starting resistor U _0zd=30%U _Φ, U _ΦBe the electrical network phase voltage.

If article one R takes place in branch road a mutually _d=955.4 Ω permanence resistor earth faults, get the hang of 1: residual voltage is ${\stackrel{\&CenterDot;}{U}}_0=\frac{U_{\mathrm{\&Phi;}}}{\sqrt{{(1+{\mathrm{\&omega;C}}_{\mathrm{\&Sigma;}}{R}_d(d+\frac{1}{R^{\&prime;}{\mathrm{\&omega;C}}_{\mathrm{\&Sigma;}}}))}^2+{\left(\mathrm{\&omega;}{C}_{\mathrm{\&Sigma;}}{R}_d\mathrm{\&upsi;}\right)}^2}}=61.8\%U_{\mathrm{\&Phi;}},$ This value is greater than starting resistor.The bucking-out system action, the excision damping resistance gets the hang of 2, and this moment, residual voltage was U ' ₀=76.9%U _ΦWith electric current increment function method result of calculation is that No. 1 branch road increment function is 1.19A, and No. 2 and No. 3 is 0A.Can obviously distinguish No. 1 branch road is ground path.

3, judge the situation of trailing type compensation network generation instant earthing with the inventive method, specific as follows: certain 10KV compensation network, three branch roads are arranged, article one, the three-phase ground capacitance of branch road is 1.01uf, the three-phase ground capacitance of second branch road is 4.201uf, article three, the three-phase ground capacitance of branch road is 15uf, electrical network total ground capacitance C _∑=20.202uf, unbalanced earth fault capacitance current I _C=36.72A.Suppose that the electrical network three-phase ground capacitance is asymmetric, be respectively a electric capacity 5.426uf relatively, b is electric capacity 7.287uf relatively, and c is electric capacity 7.287uf relatively.Electrical network ratio of damping d=5%.Adopt the trailing type bucking-out system, take off humorous degree υ=50% under the normality, the asymmetric residual voltage that causes of electrical network is about U ₀=15%U _Φ, U _ΦBe the electrical network phase voltage.If second branch road a takes place mutually through R _d=1030 Ω resistance instant earthings, the energy increment function calculation Δ S when adopting transient state ground connection ₀₁=-0.0862J, Δ S ₀₂=-23.5331J, Δ S ₀₃=7.7982J, visible Δ S ₀₂＜0 and the absolute value maximum, so correctly be judged as the 2nd branch road ground connection.As calculating S by " energy method small current earthing wire-selecting principle " described energy method ₀₁=-1.6439J, S ₀₂=1.1492J, S ₀₃=-11.531J, visible S ₀₃＜0 and the absolute value maximum, so false judgment is the 3rd branch road ground connection.

Claims (8)

1, a kind of compensation network increment function earthing wire-selecting method, it is characterized in that, by continuous detecting electrical network residual voltage, amplitude situation of change according to residual voltage, grounding phenomenon is divided into two types of permanent earth and transient state ground connection, combine with modern arc extinction compensation technology, construct the characteristic quantity that obviously to distinguish ground connection branch road and non-ground connection branch road, be called increment function, at this increment function of permanent earth is the current increment function, at this increment function of transient state ground connection is the energy increment function, searches the ground connection branch road by detecting increment function, thereby reaches the purpose of distinguishing ground connection branch road and non-ground connection branch road.

2, compensation network increment function earthing wire-selecting method according to claim 1 is characterized in that, described current increment function expression is:

$\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{I}}_{0j}=({\stackrel{\&CenterDot;}{I}}_{0j}^{\&prime;}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{bp}0j})\frac{{\stackrel{\&CenterDot;}{U}}_0-{\stackrel{\&CenterDot;}{U}}_{0\mathrm{nom}}}{{\stackrel{\&CenterDot;}{U}}_0^{\&prime;}-{\stackrel{\&CenterDot;}{U}}_{0\mathrm{nom}}}-({\stackrel{\&CenterDot;}{I}}_{0j}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{bp}0j}),(j=\mathrm{1,2}\&CenterDot;\&CenterDot;\&CenterDot;m)$

Wherein,  ₀,  ₀' for after the electrical network generation ground connection, regulate the inductance of arc suppression coil branch road or the residual voltage of the forward and backward electrical network of resistance, After electrical network generation ground connection, regulate the inductance or the forward and backward j branch road of the resistance zero-sequence current of arc suppression coil branch road, Be the natural unsymmetrical current of j branch road under the compensation network normality, U _0nomBe residual voltage under the compensation network normality.

3, compensation network increment function earthing wire-selecting method according to claim 1 and 2 is characterized in that, to the criterion of trailing type bucking-out system ground connection branch road i is: i ∈ (k, Δ I _Ok＞Δ I _Jmax, the 90-ΔΦ _Max＜| Φ _k|＜90+ ΔΦ _Max) or: $i\&Element;(k,|\mathrm{\&Delta;}{I}_{0k}|=\underset{j=1}{\overset{m}{\max }}\left(\right|\mathrm{\&Delta;}{I}_j|,90-\mathrm{\&Delta;}{\mathrm{\&Phi;}}_{\max }<|{\mathrm{\&Phi;}}_k|<90+\mathrm{\&Delta;}{\mathrm{\&Phi;}}_{\max })$ Δ I wherein _JmaxBe the non-ground connection branch road zero sequence increment function maximum that causes owing to measure error, ΔΦ _MaxBe ground connection branch road zero-sequence current increment function and the  that causes owing to measure error ₀Phase difference departs from 90 ° maximum, then Φ _iThe symbol foundation Change direction and decide, to Δ I _LThe size principle of adjusting be: $\mathrm{\&Delta;}{I}_L>K_k\frac{3\mathrm{\&Delta;}{I}_{j\max }^{\&CenterDot;}}{K_0},$ K _kBe safety factor.

4, compensation network increment function earthing wire-selecting method according to claim 1 and 2 is characterized in that, to the criterion of giving mode bucking-out system ground connection branch road i is: i ∈ (j, Δ I _j＞Δ I _Jmax, the 180-ΔΦ _Max＜| Φ _j|＜180+ ΔΦ _Max) or: $i\&Element;(k,|\mathrm{\&Delta;}{I}_{0k}|=\underset{j=1}{\overset{m}{\max }}\left(\right|\mathrm{\&Delta;}{I}_j|,180-\mathrm{\&Delta;}{\mathrm{\&Phi;}}_{\max }<|{\mathrm{\&Phi;}}_k|<180+\mathrm{\&Delta;}{\mathrm{\&Phi;}}_{\max })$ Φ wherein _iSymbol for negative, promptly the direction of ground connection branch road increment function and residual voltage are reverse, Δ I _RThe principle of adjusting be: $\mathrm{\&Delta;}{I}_R>K_k\frac{3\mathrm{\&Delta;}{I}_{j\max }}{K_0},$ K _kBe safety factor.

5, compensation network increment function earthing wire-selecting method according to claim 1 is characterized in that, described energy increment function expression is: $\mathrm{\&Delta;}{S}_{0j}={\&Integral;}_0^T(u_0\left(\mathrm{\&tau;}\right)-u_{0\mathrm{nom}}\left(\mathrm{\&tau;}\right))(i_{0j}\left(\mathrm{\&tau;}\right)-i_{\mathrm{bp}0j}\left(\mathrm{\&tau;}\right))\mathrm{d\&tau;},(j=\mathrm{1,2}\&CenterDot;\&CenterDot;\&CenterDot;m)$ Wherein T is a power frequency period, establishes t=0 ground connection, u take place constantly _0nom(t) and i _Bp0j(t) for ground connection take place before (3T ,-2T) time period residual voltage and each branch road zero-sequence current instantaneous value, u ₀(t) and i _0j(t) be after the ground connection (0, T) time period residual voltage and each branch road zero-sequence current instantaneous value.

6, compensation network increment function earthing wire-selecting method according to claim 1 or 5 is characterized in that, the reference direction of definition zero-sequence current be that then transient state ground connection branch road i route selection criterion is from the bus outflow: $i\&Element;(k,\mathrm{\&Delta;}{S}_{0k}<0,|\mathrm{\&Delta;}{S}_{0k}|=\underset{j=1}{\overset{m}{\max }}\left(\right|\mathrm{\&Delta;}{S}_{0j}|)$ Or i ∈ (k, Δ S _0k＜0, | Δ S _0k|＞Δ S _Zd) Δ S wherein _ZdBe setting value.

7, compensation network increment function earthing wire-selecting method according to claim 1 is characterized in that corresponding to the trailing type bucking-out system, method step is specific as follows:

When 1) electrical network normally moves, synchronous acquisition electrical network residual voltage and each branch road zero-sequence current, the storage data are handled the residual voltage data with DFT or FFT, obtain fundamental voltage amplitude U _0mon

2) compare residual voltage fundamental voltage amplitude U _0monWith setting value U _Zd, as greater than setting value, think that ground connection takes place, constantly t=0;

3) send the adjustment signal that makes arc suppression coil arrive the The optimal compensation state;

4) synchronous acquisition electrical network residual voltage and each branch road zero-sequence current, the storage data are analyzed the residual voltage data, obtain residual voltage amplitude U ₀, calculating K ₀=U ₀/ U _Φ

5) press $\mathrm{\&Delta;}{I}_L>K_k\frac{3\mathrm{\&Delta;}{I}_{j\max }}{K_0}$ Determine the regulated quantity of arc suppression coil, K _kGet number, Δ I greater than 1 _JmaxGet the minimum value that zero sequence current mutual inductor can accurately be measured;

6) by 5) adjustment amount provide arc suppression coil and adjust signal;

7) electrical network residual voltage and each branch road zero-sequence current after the adjustment of synchronous acquisition arc suppression coil, record data;

8) send the signal that arc suppression coil turns back to the The optimal compensation state;

9) processing 7) residual voltage data in the record data are judged earthing type;

10) if permanent earth handles 1) middle data of gathering, obtain each branch road zero-sequence current and electrical network residual voltage fundametal compoment

And  _0mon, handle 4) in the data of gathering, obtain each branch road zero-sequence current and electrical network residual voltage fundametal compoment behind the ground compensation And  ₀, handle 7) in the data of gathering, obtain each branch road zero-sequence current and electrical network residual voltage fundametal compoment after the arc suppression coil adjustment And  ₀', calculate $\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{I}}_{0j}=({\stackrel{\&CenterDot;}{I}}_{0j}^{\&prime;}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{bp}0j})\frac{{\stackrel{\&CenterDot;}{U}}_0-{\stackrel{\&CenterDot;}{U}}_{0\mathrm{nom}}}{{\stackrel{\&CenterDot;}{U}}_0^{\&prime;}-{\stackrel{\&CenterDot;}{U}}_{0\mathrm{nom}}}-({\stackrel{\&CenterDot;}{I}}_{0j}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{bp}0j}),$ It is the ground connection branch road that peaked branch road is arranged;

11) if transient state ground connection gets 1) in the data of gathering obtain each branch road zero-sequence current and electrical network residual voltage instantaneous value i before the ground connection _Bp0jAnd u _0monOne group of sampled value, get 4) in the data data of gathering, obtain each branch road zero-sequence current of period 1 and electrical network residual voltage instantaneous value i after the ground connection _0jAnd u ₀One group of sampled value, calculate increment function with numerical integration $\mathrm{\&Delta;}{S}_{0j}={\&Integral;}_0^T(u_0\left(\mathrm{\&tau;}\right)-u_{0\mathrm{nom}}\left(\mathrm{\&tau;}\right))(i_{0j}\left(\mathrm{\&tau;}\right)-i_{\mathrm{bp}0j}\left(\mathrm{\&tau;}\right))\mathrm{d\&tau;},$ There is maximum person to be the ground connection branch road.

8, compensation network increment function earthing wire-selecting method according to claim 1 is characterized in that, corresponding to giving the mode bucking-out system, method step is specific as follows:

1) together corresponding to the step 1) in the trailing type bucking-out system method step;

2) together corresponding to the step 2 in the trailing type bucking-out system method step);

3) electrical network residual voltage and each branch road zero-sequence current after the synchronous acquisition ground connection, record data;

4) send excision damping resistance signal;

5) electrical network residual voltage and each branch road zero-sequence current behind the synchronous acquisition excision damping resistance, record data;

6) processing 5) residual voltage data in the record data are judged earthing type;

7) if permanent earth handles 1) middle data of gathering, obtain each branch road zero-sequence current and electrical network residual voltage fundametal compoment I _Bp0jAnd U _0mon, handle 3) and middle data of gathering, obtain damping resistance excision each branch road zero-sequence current of back and electrical network residual voltage fundametal compoment

And  ₀, handle 5) in the data of gathering, obtain each branch road zero-sequence current and electrical network residual voltage fundametal compoment after the arc suppression coil adjustment

And  ' ₀, calculate $\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{I}}_{0j}=({\stackrel{\&CenterDot;}{I}}_{0j}^{\&prime;}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{bp}0j})\frac{{\stackrel{\&CenterDot;}{U}}_0-U_{0\mathrm{nom}}}{{\stackrel{\&CenterDot;}{U}}_0^{\&prime;}-{\stackrel{\&CenterDot;}{U}}_{0\mathrm{nom}}}-({\stackrel{\&CenterDot;}{I}}_{0j}-{\stackrel{\&CenterDot;}{I}}_{\mathrm{bp}0j}),$ It is the ground connection branch road that peaked branch road is arranged;

8) together corresponding to the step 11) in the trailing type bucking-out system method step.