CN103245878A - Single-end distance measurement method for electric transmission line single-phase earth fault - Google Patents

Abstract

The invention discloses a single-end distance measurement method for an electric transmission line single-phase earth fault. The method comprises the following steps: calculating equivalent resistance by using fault phase electric quantity in the electric transmission line protection installing place, multiplying the equivalent resistance by fault phase negative sequence current to acquire the single-phase earth fault point voltage, calculating a real part of a ratio between single-phase earth fault point voltage and electric transmission line voltage drop per unit length to acquire an additional fault distance caused by transition resistance, and using the real part of the ratio to subtract the additional fault distance so as to acquire a fault distance from the electric transmission line protection installing place to the single-phase earth fault point. According to the method, the problem about the effect of transition resistance on single-end fault distance measurement accuracy is solved, higher distance measurement accuracy is achieved in case of electric transmission line single phase high resistance ground fault, the distance measurement principle is simple, the process is easy to realize, the fault distance is directly calculated without adopting the search algorithm, the distance measurement speed is high, and the instantaneity is high.

Description

A kind of transmission line one-phase earth fault method of single end distance measurement

Technical field

The present invention relates to the relay protection of power system technical field, specifically relate to a kind of transmission line one-phase earth fault method of single end distance measurement.

Background technology

The transmission line of electricity one-end fault ranging method only utilizes transmission line of electricity one end electric parameters to carry out localization of fault, need not communication and data sync equipment, and operating cost is low and algorithm stable, obtains widespread use in transmission line of electricity.

One-end fault ranging method mainly is divided into traveling wave method and impedance method.Traveling wave method utilizes the transmission character of fault transient travelling wave to carry out one-end fault ranging, and the distance accuracy height is not influenced by the method for operation, excessive resistance etc., but very high to the sampling rate requirement, needs special wave recording device, application cost height.Impedance method utilizes voltage, the magnitude of current after the fault to calculate the fault loop impedance, carry out one-end fault ranging according to the characteristic that line length is directly proportional with impedance, simple and reliable, but it is serious that distance accuracy is subjected to the transition resistance influence, when especially transition resistance is very big, the one-end fault ranging result understands substantial deviation true fault distance, even exceed the transmission line of electricity total length, make the one-end fault ranging result lose reference value, can't be for the electric power system fault track walker provide abort situation information accurately and effectively, be unfavorable for that abort situation searches rapidly and quick elimination of fault.Therefore, a kind of transmission line one-phase earth fault method of single end distance measurement that not influenced by transition resistance of research has very important meaning.

Summary of the invention

The objective of the invention is to overcome the deficiency that prior art exists, a kind of transmission line one-phase earth fault method of single end distance measurement that is not subjected to transition resistance to influence, accurately measure fault distance is provided.

A kind of transmission line one-phase earth fault method of single end distance measurement is characterized in that, comprises the steps:

(1) the fault phase voltage of protector measuring line protection installation place

, fault phase negative-sequence current

, the fault phase current

And zero-sequence current , as input quantity; Wherein, φ=A, B, C phase;

(2) protective device calculates equivalent resistance Wherein, z ₁, z ₀Be respectively unit length transmission line of electricity positive sequence impedance, zero sequence impedance;

For

Imaginary part;

For

Imaginary part.

(3) protective device utilization

Deduct equivalent resistance k with

Product obtain the line protection installation place to the fault distance x of singlephase earth fault point:

$x=\mathrm{Re}[\frac{{\stackrel{\·}{U}}_{\mathrm{\φ}}}{z_1({\stackrel{\·}{I}}_{\mathrm{\φ}}+\frac{z_0-z_1}{z_1}{\stackrel{\·}{I}}_0)}-\frac{\mathrm{Re}\left[\frac{{\stackrel{\·}{I}}_{\mathrm{\φ}2}}{z_1({\stackrel{\·}{I}}_{\mathrm{\φ}}+\frac{z_0-z_1}{z_1}{\stackrel{\·}{I}}_0)}\right]\mathrm{Im}\left[\frac{{\stackrel{\·}{U}}_{\mathrm{\φ}}}{z_1({\stackrel{\·}{I}}_{\mathrm{\φ}}+\frac{z_0-z_1}{z_1}{\stackrel{\·}{I}}_0)}\right]}{\mathrm{Im}\left[\frac{{\stackrel{\·}{I}}_{\mathrm{\φ}2}}{z_1({\stackrel{\·}{I}}_{\mathrm{\φ}}+\frac{z_0-z_1}{z_1}{\stackrel{\·}{I}}_0)}\right]}$

Wherein,

For

Real part;

For

Real part.

The present invention has following positive achievement compared with prior art:

The inventive method at first utilizes the fault phase electric parameters of line protection installation place to calculate equivalent resistance; utilize equivalent resistance to multiply by fault phase negative-sequence current and wait until the singlephase earth fault point voltage; the real part that calculates singlephase earth fault point voltage and the ratio of unit length transmission line of electricity voltage drop obtains the additional fault distance that causes because of transition resistance, utilizes the real part of the ratio of fault phase voltage and the voltage drop of unit length transmission line of electricity to deduct additional fault apart from the fault distance that obtains the line protection installation place and arrive singlephase earth fault point.The inventive method has overcome the influence problem of transition resistance to the one-end fault ranging precision, has very high distance accuracy during the single-phase high resistance earthing fault of transmission line of electricity, range measurement principle is simple, program realizes easily, and need not to adopt searching algorithm directly to calculate fault distance, range finding speed is fast, and is real-time.

Description of drawings

Fig. 1 is for using circuit transmission system synoptic diagram of the present invention.

Embodiment

According to Figure of description technical scheme of the present invention is done further detailed presentations below.

Fig. 1 is for using circuit transmission system synoptic diagram of the present invention.PT is that voltage transformer (VT), CT are current transformer among Fig. 1.Protective device is sampled to the current waveform of the voltage waveform summation current transformer CT of the voltage transformer pt of line protection installation place and is obtained voltage, current instantaneous value, and voltage, current instantaneous value that its sampling obtains is utilized the fault phase voltage of Fourier algorithm computing electric power line protection installation place , fault phase negative-sequence current

, the fault phase current

And zero-sequence current

, as input quantity; Wherein, φ=A phase, B phase, C phase.

Protective device utilizes the fault phase voltage of line protection installation place

, fault phase negative-sequence current , the fault phase current

And zero-sequence current

Calculate equivalent resistance

Wherein, z ₁, z ₀Be respectively unit length transmission line of electricity positive sequence impedance, zero sequence impedance; For

Imaginary part;

For

Imaginary part.

Owing to satisfy

Therefore, the inventive method utilization Deduct equivalent resistance k with

Product obtain the line protection installation place to the fault distance x of singlephase earth fault point:

$x=\mathrm{Re}[\frac{{\stackrel{\·}{U}}_{\mathrm{\φ}}}{z_1({\stackrel{\·}{I}}_{\mathrm{\φ}}+\frac{z_0-z_1}{z_1}{\stackrel{\·}{I}}_0)}-\frac{\mathrm{Re}\left[\frac{{\stackrel{\·}{I}}_{\mathrm{\φ}2}}{z_1({\stackrel{\·}{I}}_{\mathrm{\φ}}+\frac{z_0-z_1}{z_1}{\stackrel{\·}{I}}_0)}\right]\mathrm{Im}\left[\frac{{\stackrel{\·}{U}}_{\mathrm{\φ}}}{z_1({\stackrel{\·}{I}}_{\mathrm{\φ}}+\frac{z_0-z_1}{z_1}{\stackrel{\·}{I}}_0)}\right]}{\mathrm{Im}\left[\frac{{\stackrel{\·}{I}}_{\mathrm{\φ}2}}{z_1({\stackrel{\·}{I}}_{\mathrm{\φ}}+\frac{z_0-z_1}{z_1}{\stackrel{\·}{I}}_0)}\right]}$

Wherein,

For

Real part;

For

Real part.

The inventive method at first utilizes the fault phase electric parameters of line protection installation place to calculate equivalent resistance; utilize equivalent resistance to multiply by fault phase negative-sequence current and wait until the singlephase earth fault point voltage; the real part that calculates singlephase earth fault point voltage and the ratio of unit length transmission line of electricity voltage drop obtains the additional fault distance that causes because of transition resistance, utilizes the real part of the ratio of fault phase voltage and the voltage drop of unit length transmission line of electricity to deduct additional fault apart from the fault distance that obtains the line protection installation place and arrive singlephase earth fault point.The inventive method has overcome the influence problem of transition resistance to the one-end fault ranging precision, has very high distance accuracy during the single-phase high resistance earthing fault of transmission line of electricity, range measurement principle is simple, program realizes easily, and need not to adopt searching algorithm directly to calculate fault distance, range finding speed is fast, and is real-time.

The above only is preferred embodiment of the present invention; but protection scope of the present invention is not limited thereto; anyly be familiar with those skilled in the art in the technical scope that the present invention discloses, the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.

Claims (1)

1. a transmission line one-phase earth fault method of single end distance measurement is characterized in that, comprises the steps:

(1) the fault phase voltage of protector measuring line protection installation place

, fault phase negative-sequence current , the fault phase current

And zero-sequence current

, as input quantity; Wherein, φ=A, B, C phase;

(2) protective device calculates equivalent resistance

Wherein, z ₁, z ₀Be respectively unit length transmission line of electricity positive sequence impedance, zero sequence impedance;

For

Imaginary part;

For Imaginary part;

(3) protective device utilization Deduct equivalent resistance k with

Product obtain the line protection installation place to the fault distance of singlephase earth fault point

:

$x=\mathrm{Re}[\frac{{\stackrel{\·}{U}}_{\mathrm{\φ}}}{z_1({\stackrel{\·}{I}}_{\mathrm{\φ}}+\frac{z_0-z_1}{z_1}{\stackrel{\·}{I}}_0)}-\frac{\mathrm{Re}\left[\frac{{\stackrel{\·}{I}}_{\mathrm{\φ}2}}{z_1({\stackrel{\·}{I}}_{\mathrm{\φ}}+\frac{z_0-z_1}{z_1}{\stackrel{\·}{I}}_0)}\right]\mathrm{Im}\left[\frac{{\stackrel{\·}{U}}_{\mathrm{\φ}}}{z_1({\stackrel{\·}{I}}_{\mathrm{\φ}}+\frac{z_0-z_1}{z_1}{\stackrel{\·}{I}}_0)}\right]}{\mathrm{Im}\left[\frac{{\stackrel{\·}{I}}_{\mathrm{\φ}2}}{z_1({\stackrel{\·}{I}}_{\mathrm{\φ}}+\frac{z_0-z_1}{z_1}{\stackrel{\·}{I}}_0)}\right]}$

Wherein, For

Real part;

For Real part.

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