CN104578008A - Zero-sequence direction element maloperation prevention method - Google Patents

Abstract

The invention discloses a zero-sequence direction element maloperation prevention method. The method comprises the following steps that (1) the phase current at a line protection mounting position is acquired; (2) the fault components of the phase current are extracted; (3) whether a maloperation prevention algorithm is started or not is judged according to the starting criteria of the maloperation prevention algorithm, and if yes, the step (4) is executed; (4) the similarity of all phase fault component current waveforms is compared; (5) a perfect circuit is selected according to the similarity comparison result. If the three-phase fault component current waveforms are basically the same, namely the similarity is high, the circuit is judged to be the perfect circuit, and zero-sequence direction elements are locked; if the three-phase fault component current waveforms are large in difference, namely the similarity is low, the circuit is judged to be a fault circuit, and the zero-sequence direction elements are not locked. According to the method, the perfect circuit and the fault circuit can be identified only by circuit single-end currents, the maloperation accidents of the perfect circuit zero-sequence direction elements due to mutual inductance between the circuits are avoided, and the action performance of the zero-sequence direction elements is effectively improved.

Description

A kind of zero-sequence direction component faulty action preventing method

[technical field]

The present invention relates to power system transmission line relay protection field, particularly a kind of zero-sequence direction component faulty action preventing method.

[background technology]

Multi-circuit lines on the same tower Application comparison is general, especially economically developed and densely populated Japan and Some European countries use more.In Germany, for effectively utilizing line corridor, all newly-built circuits of statutory regulation must wiring on the same tower more than twice.In its high pressure and supertension line, be conventional line four times with tower, mostly be six times most.Tokyo Electric Power, because of area under one's jurisdiction shortage of land resource, for reducing line corridor land used, adopts multiloop parallel erected on same tower as far as possible.110kV and above circuit majority are same tower four times, 500kV circuit except early stage 2 be except single loop, all the other are same pylon double back.At present, the maximum feeder number of Japanese parallel erected on same tower is eight times.In recent years, along with the quickening of power grid construction speed, the regional multi-circuit lines on the same tower application such as Beijing, Guangdong flourishing at Economic contrast, planning facility is intensive is also commonplace, through the investigation and application of more than ten years, parallel erected on same tower there has been significant progress, becomes a ripe technology gradually.Domestic Article 1 is built in nineteen ninety-five with tower 4 loop line road, for 220kV, the 110kV in Zhichunli-Qinghe, Beijing area is with tower circuit.This circuit have employed self-supporting drum type tower, and each loop three-phase conducting wire adopts vertical arrangement, totally seven layers of cross-arm.Upper strata is lightning conducter support, and middle three layers is 220kV wire cross-arm, below three layers be 110kV wire cross-arm.In order to limit wire windage yaw, design span is no more than 300m.In order to improve stability, control tower overall height is at about 50m.Ankang-southern suburbs (Xi'an) line is the parallel erected on same tower double-circuit line of domestic 330kV electric pressure of building the earliest, is that safe and comfortable power plant uniquely sends basic routing line, is the important channel connecting safe and comfortable power plant and Shaanxi Power System.Due to the extensive use of multi-circuit lines on the same tower, its Related Technical Issues research is one of hot research direction of electric power system.

With regard to fault signature, the main distinction of multi-circuit lines on the same tower compared with common single back line is its impact being subject to adjacent lines.For the operational mode that there is circuit contact, fault signature not only needs the acute variation considering the corresponding phase electric parameters of adjacent lines, also needs the impact considering mutual inductance between different loop line.For the operational mode that there is not circuit contact, then fault signature only needs the impact considering mutual inductance between different loop line.Perfecting the electric parameters change that circuit occurs when fault makes it there is malfunction risk, and in single line down situation, the malfunction problem of adjacent lines zero-sequence direction component is of common occurrence at each electric pressure electrical network, often causes the misoperation of zero-sequence voltage injection.For long distance with the corridor construction of line, due to mutual inductance effect between line, there is malfunction problem in zero-sequence voltage injection equally.

To sum up analyze; for have light current strong magnetic contact multi-circuit lines on the same tower and long distance with the corridor construction of line; although zero-sequence voltage injection exists selectivity and the sensitivity problem of faulty line protection, the malfunction problem perfecting route protection is also very outstanding, should cause enough attention.

[summary of the invention]

The object of the present invention is to provide a kind of zero-sequence direction component faulty action preventing method, perfect circuit zero-sequence voltage injection misoperation problem with what solve that mutual inductance causes.

To achieve these goals, the present invention adopts following technical scheme:

A kind of zero-sequence direction component faulty action preventing method, comprises the following steps:

(1) phase current of route protection installation place is obtained;

(2) fault component of phase current is extracted;

(3) according to the starting criteria of faulty action preventing algorithm, judge whether to start faulty action preventing algorithm; If started, enter step (4);

(4) similarity of each phase fault current weight waveform in more each circuit; Select according to similarity-rough set result and perfect circuit, and give locking to its zero-sequence direction component, the zero-sequence direction component of faulty line then refuses locking.

By calculating the similarity between three-phase fault current weight model error faults current weight waveform between any two in step (4), and adopt any two the tectonic model error criterions in three model errors; If two of a certain circuit model error values are all less than setting value, judge that this circuit is as perfecting circuit, and locking is given to zero-sequence direction component; If two of a certain circuit model error values are not all less than setting value, then judge that this circuit is as faulty line, refuses locking to zero-sequence direction component.

In step (3), the starting criteria of faulty action preventing algorithm is:

$\left|\mathrm{\Δ}{\stackrel{\·}{I}}_a\right|>I_{\mathrm{set}},\left|{\mathrm{\Δ}\stackrel{\·}{I}}_b\right|>I_{\mathrm{set}},\left|{\mathrm{\Δ}\stackrel{\·}{I}}_c\right|>I_{\mathrm{set}}.$

I _setvalue is 0.2 times of zero-sequence direction component starting current setting value.

In step (4), three-phase fault current weight model error is between any two:

$r({\mathrm{\Δi}}_{\mathrm{\α}},{\mathrm{\Δi}}_{\mathrm{\β}})=\frac{\underset{n=0}{\overset{N/2-1}{\mathrm{\Σ}}}|\mathrm{\Δ}{i}_{\mathrm{\α}}\left(n\right)-{\mathrm{\Δi}}_{\mathrm{\β}}\left(n\right)|}{\underset{n=0}{\overset{N/2-1}{\mathrm{\Σ}}}\left(\right|{\mathrm{\Δi}}_{\mathrm{\α}}\left(n\right)|+|{\mathrm{\Δi}}_{\mathrm{\β}}\left(n\right)\left|\right)}$

Wherein, Δ i _αwith Δ i _βfor two in A, B, C three-phase fault current weight.

Step (4) if in model error between seletion calculation A, B two-phase and B, C phase to phase fault current weight, then model error criterion is:

R (Δ i _a, Δ i _b) <r _setand r (Δ i _b, Δ i _c) <r _set

Wherein, r _setany number in (0,0.8) scope can be got.For ensureing the reliability of criterion, r _setcan be taken as 0.4.

The technical problem that the present invention solves has: when 1, strong next loop line of magnetic situation of light current breaks down, faulty line and the fault signature essential difference perfecting circuit; 2, to faulty line and the description and the recognition methods that perfect line fault feature essential difference; 3, circuit zero-sequence direction component locking measure is perfected.

Key technology of the present invention is: when strong next loop line of magnetic situation of (1) light current breaks down, perfect the electric characteristic essential difference of circuit and faulty line; (2) reliable recognition of circuit is perfected.

Compared with existing zero-sequence direction component faulty action preventing method, the present invention has following three advantages:

1, only utilize this line one-terminal current information can carry out perfecting circuit and faulty line identification, what be conducive to preventing mutual inductance between line from causing perfects the malfunction of circuit zero-sequence direction component;

2, the calculating of model error criterion is carried out in time domain, and amount of calculation is little, and data window is short, and distinguishing speed is fast;

3, be applicable to unsymmetrical short-circuit and disconnection fault simultaneously, and there is higher sensitivity.

The invention provides a kind of zero-sequence direction component faulty action preventing method, zero-sequence direction component precision maneuver when line fault can be ensured, avoid the misoperation perfecting circuit zero-sequence voltage injection.For have light current strong magnetic contact multi-circuit lines on the same tower or long distance with the corridor construction of line, in various transposition situation, the average mutual impedance of the positive-negative sequence between loop line coefficient is very little, can ignore, and zero-sequence mutual inductance is still very large.Therefore, when a loop line generation unsymmetrical short-circuit or disconnection fault, the phase current change perfecting circuit is only caused by zero-sequence mutual inductance, it is characterized by three-phase current with sudden change; And the phase current change of faulty line causes primarily of this line fault, simultaneously containing positive sequence, negative phase-sequence and zero-sequence component, it is characterized by the sudden change of three-phase current difference.The similarity of three-phase fault current weight waveform can be utilized accordingly to identify and to perfect circuit, and its zero-sequence direction component of locking, thus ensure the reliable selectivity action of relaying protection.

[accompanying drawing explanation]

Fig. 1 is the single line structure chart of common-tower double-return line.

Zero mould network diagram when Fig. 2 is a loop line generation disconnection fault in common-tower double-return line.

Fig. 3 perfects the waveform of the residual voltage at circuit and faulty line two ends, current waveform and residual voltage and current and phase difference when being a loop line generation single-phase wire break fault in common-tower double-return line; Wherein Fig. 3 (a), Fig. 3 (b) are for perfecting the waveform at circuit two ends, and Fig. 3 (c), Fig. 3 (d) are the waveform at faulty line two ends.Definition is the positive direction of zero-sequence current by line flows to generatrix direction.In order to compare the phase relation of residual voltage and electric current, the amplitude of residual voltage is carried out standardization process.

Fig. 4 perfects the waveform of the residual voltage at circuit and faulty line two ends, current waveform and residual voltage and current and phase difference when being a loop line generation single phase ground fault in common-tower double-return line, wherein Fig. 4 (a), Fig. 4 (b) are for perfecting the waveform at circuit two ends, and Fig. 4 (c), Fig. 4 (d) are the waveform at faulty line two ends.

Fig. 5 is the model error waveform perfecting circuit and faulty line two ends when A phase disconnection fault occurs a loop line in common-tower double-return line, wherein Fig. 5 (a), Fig. 5 (b) are for perfecting the model error waveform at circuit two ends, the model error waveform that Fig. 5 (c), Fig. 5 (d) are faulty line two ends.

Fig. 6 is the model error waveform perfecting circuit and faulty line two ends when A phase earth fault occurs a loop line in common-tower double-return line, wherein Fig. 6 (a), Fig. 6 (b) are for perfecting the model error waveform at circuit two ends, the model error waveform that Fig. 6 (c), Fig. 6 (d) are faulty line two ends.

[embodiment]

Below in conjunction with accompanying drawing, the invention will be further described.

The invention provides a kind of zero-sequence direction component faulty action preventing method, its main purpose is the misoperation problem solving traditional zero-sequence voltage injection.First identify after a failure and perfect circuit and its zero-sequence direction component of locking, prevent the generation perfecting the misoperation of circuit zero-sequence voltage injection.

General principle of the present invention is: for have light current strong magnetic contact multi-circuit lines on the same tower or long distance with the corridor construction of line, wherein after a loop line generation unsymmetrical short-circuit or disconnection fault, the phase current change perfecting circuit is caused by the zero-sequence mutual inductance of faulty line, so show the fault signature of three-phase current with sudden change; The phase current change of faulty line causes primarily of fault, and fault component electric current not only comprises zero-sequence component, also containing positive sequence and negative sequence component, so show the fault signature of three-phase current difference sudden change.Based on this fault signature difference, the similarity of three-phase fault current weight waveform can be utilized to identify and to perfect circuit, and its zero-sequence direction component of locking.

Under the zero-sequence voltage injection generation misoperation perfecting circuit only appears at " the strong magnetic of light current " situation.For the multiple-circuit on same tower of the two ends shown in Fig. 1 without electrical link; when there is single-phase wire break fault in loop line I; from the phase relation of zero-sequence network figure (Fig. 2) and residual voltage current waveform (Fig. 3); the correct failure judgement of zero-sequence voltage injection of faulty line occurs in district; it is troubles inside the sample space that the zero-sequence voltage injection perfecting circuit then judges fault by accident, thus causes misoperation.When single phase ground fault occurs loop line I, can judge that the zero-sequence voltage injection perfecting circuit can misoperation equally by Fig. 4.The basic reason perfecting the misoperation of circuit zero-sequence voltage injection is the zero-sequence mutual inductance effect between loop line.Under the effect of zero-sequence mutual inductance, the three-phase current perfecting circuit shows the fault signature of identical mutation, and the three-phase current of fault wire is less by the zero-sequence mutual inductance effect perfecting circuit, identical with in single loop line situation of fault signature, does not have the feature of three-phase current with sudden change.According to the difference of fault signature, the similarity of three-phase fault current weight waveform can be utilized to identify and to perfect circuit, and its zero-sequence direction component of locking, thus prevent zero-sequence voltage injection misoperation.

The principle of Model Identification:

The method of Model Identification is successfully applied to relay protection field, its basic ideas be first in district and the network of external area error carry out Equivalent Modeling, then according to two kinds of models with actual measurement electric parameters matching degree distinguish in district and external area error.Concrete method of discrimination is realized by model error usually, to choose in district or is benchmark model outside district, and the formula of model error is as follows:

$r(f,g)=\frac{\mathrm{\&Sigma;}|f-g|}{\mathrm{\&Sigma;}\left|f\right|+\left|g\right|}---\left(1\right)$

Wherein, f is the electric parameters of actual measurement, and g is the electric parameters of benchmark model.

For multi-circuit lines on the same tower or long distance with the corridor construction of line, the difference perfecting circuit and faulty line three-phase fault current weight wave-form similarity can be utilized, build the equivalent model perfecting circuit and faulty line.For perfecting circuit, equivalent model is that three-phase fault current weight waveform is substantially identical, the model that namely similarity is higher; For faulty line, equivalent model is that three-phase fault current weight waveform difference is comparatively large, the model that namely similarity is lower.Thus, tectonic model error the differentiation perfecting circuit can be carried out.With A, B phase fault current weight for example, the formula of model error is as follows:

$r({\mathrm{\&Delta;i}}_a,{\mathrm{\&Delta;i}}_b)=\frac{\underset{n=0}{\overset{N/2-1}{\mathrm{\&Sigma;}}}|\mathrm{\&Delta;}{i}_a\left(n\right)-{\mathrm{\&Delta;i}}_b\left(n\right)|}{\underset{n=0}{\overset{N/2-1}{\mathrm{\&Sigma;}}}\left(\right|{\mathrm{\&Delta;i}}_a\left(n\right)|+|{\mathrm{\&Delta;i}}_b\left(n\right)\left|\right)}---\left(2\right)$

Wherein, N is every cycle sampling number.

For perfecting circuit, the model error between three-phase fault current weight is 0; And for faulty line, the model error between three-phase fault current weight is not 0 entirely.

The invention provides a kind of zero-sequence direction component faulty action preventing method, specifically comprise the following steps:

(1) three-phase voltage of route protection installation place and electric current are gathered, and carry out A/D conversion, obtain the digital quantity of three-phase voltage and electric current.

(2) electric parameters of the three-phase voltage that obtains according to step (1) of the starting element of protective relaying device and electric current judges whether starting failure decision logic.If started, enter step (3).

(3) extract the fault component of phase current, also only can extract the power frequency composition of fault component.

(4) according to the starting criteria of faulty action preventing algorithm, judge whether to start faulty action preventing algorithm.If started, enter step (5).

The starting criteria of faulty action preventing algorithm is:

$\left|\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{I}}_a\right|>I_{\mathrm{set}},\left|{\mathrm{\&Delta;}\stackrel{\&CenterDot;}{I}}_b\right|>I_{\mathrm{set}},\left|{\mathrm{\&Delta;}\stackrel{\&CenterDot;}{I}}_c\right|>I_{\mathrm{set}}.$

I _setvalue is 0.2 times of zero-sequence direction component starting current setting value.

(5) model error between three-phase fault current weight is calculated.

For a loop line, A phase earth fault occurs, the three-phase fault current weight relation of fault wire is as follows

$\left\{\begin{array}{c}\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{I}}_a=({2C}_1+C_0){\stackrel{\&CenterDot;}{I}}_0\\ \mathrm{\&Delta;}{\stackrel{\&CenterDot;}{I}}_b={\mathrm{\&Delta;}\stackrel{\&CenterDot;}{I}}_c=(C_0-C_1){\stackrel{\&CenterDot;}{I}}_0\end{array}\right.---\left(3\right)$

Wherein, C ₁, C ₀for positive sequence and zero sequence diverting coefficient, for the zero-sequence current of fault point.

Usual C ₁and C ₀numerical value is suitable, so when there is A phase earth fault, the fault component electric current of B, C phase is much smaller than the fault component electric current of A phase.Therefore, the model error calculated is:

$\left\{\begin{array}{c}r({\mathrm{\&Delta;i}}_a,{\mathrm{\&Delta;i}}_b)\&ap;1\\ r({\mathrm{\&Delta;i}}_a,{\mathrm{\&Delta;i}}_c)\&ap;1\\ r({\mathrm{\&Delta;i}}_b,{\mathrm{\&Delta;i}}_c)=1\end{array}\right.---\left(4\right)$

The three-phase fault current weight perfecting circuit meets following relation:

$\mathrm{\&Delta;}{\stackrel{\&CenterDot;}{I}}_a={\mathrm{\&Delta;}\stackrel{\&CenterDot;}{I}}_b={\mathrm{\&Delta;}\stackrel{\&CenterDot;}{I}}_c---\left(5\right)$

Calculating model error is:

$\left\{\begin{array}{c}r({\mathrm{\&Delta;i}}_a,{\mathrm{\&Delta;i}}_b)\&ap;0\\ r({\mathrm{\&Delta;i}}_a,{\mathrm{\&Delta;i}}_c)\&ap;0\\ r({\mathrm{\&Delta;i}}_b,{\mathrm{\&Delta;i}}_c)=0\end{array}\right.---\left(6\right)$

Model error result of calculation according to formula (4) and formula (6) reliably can be distinguished faulty line and perfect circuit.

(6) select according to model error result of calculation and perfect line, and give locking to the zero-sequence direction component perfecting circuit, the zero-sequence direction component of faulty line refuses locking.

According to actual derivation of equation result, under various unsymmetrical short-circuit and disconnection fault situation, the model error value perfected between circuit three-phase fault current weight is 0, and the model error between fault wire three-phase fault current weight has two numerical value at least close to 1.Therefore, the identification that any two model errors carry out perfecting circuit can only be calculated.

If the model error between seletion calculation A, B two-phase and B, C phase to phase fault current weight, then model error criterion is:

R (Δ i _a, Δ i _b) <r _setand r (Δ i _b, Δ i _c) <r _set

For the multi-circuit lines on the same tower of reality or long distance with the corridor construction of line, be the reliability ensureing criterion, r _setcan 0.4 be got.

More than be particular content of the present invention.

When Fig. 3 is a loop line generation single-phase wire break fault in common-tower double-return line, perfect the waveform of the residual voltage at circuit and faulty line two ends, current waveform and residual voltage and current and phase difference.As can be seen from the figure, the residual voltage and the current phase relation that perfect circuit and faulty line two ends meet residual voltage leading current about 90 degree, thus the positive direction criterion of circuit two ends zero-sequence direction component is all set up.So the zero-sequence voltage injection of faulty line can occur in district by reliable Judging fault, and the zero-sequence voltage injection erroneous judgement fault perfecting circuit occurs in district, thus occurs misoperation.

When Fig. 4 is a loop line generation single phase ground fault in common-tower double-return line, perfect the waveform of the residual voltage at circuit and faulty line two ends, current waveform and residual voltage and current and phase difference.As can be seen from the figure, the residual voltage and the current phase relation that perfect circuit and faulty line two ends meet residual voltage leading current about 90 degree, thus the positive direction criterion of circuit two ends zero-sequence direction component is all set up.So the zero-sequence voltage injection of faulty line can occur in district by reliable Judging fault, and the zero-sequence voltage injection erroneous judgement fault perfecting circuit occurs in district, thus occurs misoperation.

Fig. 5, when A phase disconnection fault occurs a loop line in common-tower double-return line, perfects the model error waveform at circuit and faulty line two ends.As can be seen from the figure, the model error value perfecting circuit two ends is 0, and much smaller than setting value 0.4, model error criterion is set up; The model error value at faulty line two ends is about 1 and 0, and model error criterion is false.Therefore, adopt this criterion reliably to select and perfect circuit.

Fig. 6, when A phase earth fault occurs a loop line in common-tower double-return line, perfects the model error waveform at circuit and faulty line two ends.As can be seen from the figure, the model error value perfecting circuit two ends is 0, and much smaller than setting value 0.4, model error criterion is set up; The model error value at fault wire two ends is about 1 and 0, and model error criterion is false.Therefore, adopt this criterion reliably to select and perfect circuit.

Comprehensive above analysis, when in common-tower double-return line, asymmetric earth fault and disconnection fault occur a loop line, the zero-sequence direction component perfecting circuit can judge fault direction by accident.Adopt model error criterion reliably to select and perfect circuit, thus prevent the misoperation perfecting circuit zero-sequence voltage injection.For having the multi-circuit lines on the same tower of light current strong magnetic contact or long distance with the corridor construction of line, model error identification is adopted to perfect the zero-sequence direction component faulty action preventing method of circuit applicable equally.

Claims (1)

1. a zero-sequence direction component faulty action preventing method, is characterized in that, comprises the following steps:

(1) phase current of route protection installation place is obtained;

(2) fault component of phase current is extracted;

(3) according to the starting criteria of faulty action preventing algorithm, judge whether to start faulty action preventing algorithm; If started, enter step (4);

(4) similarity of each phase fault current weight waveform in more each circuit; Select according to similarity-rough set result and perfect circuit, and give locking to its zero-sequence direction component, the zero-sequence direction component of faulty line then refuses locking.