CN103219715B - Based on the line interphase fault relay protection method of fault impedance phase characteristic - Google Patents

Abstract

The invention discloses a kind of line interphase fault relay protection method based on fault impedance phase characteristic.First the inventive method utilizes the fault voltage between phases of line protection installation place, between fault three-phase current and fault phase, negative sequence voltage calculates the line fault impedance of phase fault point to line protection setting range place; then judge that phase fault point drops in (135 ° 225 °) scope to the phase angle of the line fault impedance at line protection setting range place whether to set up; if set up, then protective device sends action trip signal.The inventive method can correct action message when the alternate high resistant short trouble of transmission line, overcomes transition resistance and load current to the impact of Perfomance of protective relaying, is applicable to the relaying protection of the whole failure process of electric transmission line phase fault.

Description

Based on the line interphase fault relay protection method of fault impedance phase characteristic

Technical field

The present invention relates to Relay Protection Technology in Power System field, specifically relate to a kind of line interphase fault relay protection method based on fault impedance phase characteristic.

Background technology

Tradition phase distance protection utilizes the ratio calculation line fault impedance of fault voltage between phases and fault three-phase current , due to , therefore .Thus can obtain, the measurement result of traditional phase distance protection measurement circuitry fault impedance is made up of two parts: a part is the line fault impedance xz of reaction true fault distance ₁, another part is the additional fault impedance because transition resistance causes .Wherein, for fault voltage between phases; for phase fault point voltage; for fault three-phase current; R _ffor transition resistance; for flowing through the electric current of phase fault point; φ φ=AB, BC, CA phase; z ₁for unit length electric transmission line positive sequence impedance; X is the fault distance of line protection installation place to phase fault point.

Transition resistance produce additional fault impedance can cause traditional phase distance protection tripping or malfunction, traditional phase distance protection tripping can make fault can not in time and electrical network isolate, unfavorable to power grid operation; Tradition phase distance protection malfunction then can causing trouble expanded range, even causes the large transfer of electric network swim, and then causes the generation of electric grid large area power cut accident.

Summary of the invention

The object of the invention is to the deficiency overcoming prior art existence, provide a kind of performance not by the line interphase fault relay protection method based on fault impedance phase characteristic that transition resistance and load current affect.

For completing above-mentioned purpose, the present invention adopts following technical scheme:

(1) current waveform of protective device to the voltage waveform summation current transformer CT of the voltage transformer pt of line protection installation place carries out sampling and obtains voltage, current instantaneous value, and utilizes Fourier algorithm computing electric power line to protect the fault voltage between phases of installation place to its voltage, current instantaneous value obtained of sampling , fault three-phase current and negative sequence voltage between fault phase , as input variable; Wherein, φ φ=AB, BC, CA phase;

(2) protective device utilizes the fault voltage between phases of line protection installation place , fault three-phase current and negative sequence voltage between fault phase calculate the line fault impedance Δ z of phase fault point to line protection setting range place:

$\mathrm{\Δz}=\frac{\mathrm{Im}\left[\frac{{\stackrel{\·}{U}}_{\mathrm{\φ\φ}}}{z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}}\right]}{\mathrm{Im}\left[\frac{{\stackrel{\·}{U}}_{\mathrm{\φ\φ}2}}{z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}{z}_1}\right]}\frac{{\stackrel{\·}{U}}_{\mathrm{\φ\φ}2}}{z_1}-{\stackrel{\·}{U}}_{\mathrm{\φ\φ}}+z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}{x}_{\mathrm{set}}$

Wherein, z ₁for unit length electric transmission line positive sequence impedance; for imaginary part; for imaginary part; x _setfor line protection setting range; φ φ=AB, BC, CA phase;

(3) protective device judges that phase fault point meets 135 ° of < Arg [Δ z] < 225 ° to the phase angle Arg [Δ z] of the line fault impedance Δ z at line protection setting range place and whether sets up; if set up, then protective device sends action trip signal.

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

First the inventive method utilizes the fault voltage between phases of line protection installation place, between fault three-phase current and fault phase, negative sequence voltage calculates the line fault impedance of phase fault point to line protection setting range place; then judge that phase fault point drops in (135 ° 225 °) scope to the phase angle of the line fault impedance at line protection setting range place whether to set up; if set up, then protective device sends action trip signal.The inventive method can correct action message when the alternate high resistant short trouble of transmission line, overcomes transition resistance and load current to the impact of Perfomance of protective relaying, is applicable to the relaying protection of the whole failure process of electric transmission line phase fault.

Accompanying drawing explanation

Fig. 1 is application multi-line power transmission system schematic of the present invention.

Embodiment

According to Figure of description, technical scheme of the present invention is expressed in further detail below.

Fig. 1 is application multi-line power transmission system schematic of the present invention.In Fig. 1, PT is voltage transformer, CT is current transformer.The current waveform of protective device to the voltage waveform summation current transformer CT of the voltage transformer pt of line protection installation place carries out sampling and obtains voltage, current instantaneous value, and utilizes Fourier algorithm computing electric power line to protect the fault voltage between phases of installation place to its voltage, current instantaneous value obtained of sampling , fault three-phase current and negative sequence voltage between fault phase , as input variable; Wherein, φ φ=AB, BC, CA phase.

Protective device utilizes the fault voltage between phases of line protection installation place , fault three-phase current and negative sequence voltage between fault phase calculate the line fault impedance Δ z of phase fault point to line protection setting range place:

$\mathrm{\&Delta;z}=\frac{\mathrm{Im}\left[\frac{{\stackrel{\&CenterDot;}{U}}_{\mathrm{\&phi;\&phi;}}}{z_1{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;\&phi;}}}\right]}{\mathrm{Im}\left[\frac{{\stackrel{\&CenterDot;}{U}}_{\mathrm{\&phi;\&phi;}2}}{z_1{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;\&phi;}}{z}_1}\right]}\frac{{\stackrel{\&CenterDot;}{U}}_{\mathrm{\&phi;\&phi;}2}}{z_1}-{\stackrel{\&CenterDot;}{U}}_{\mathrm{\&phi;\&phi;}}+z_1{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;\&phi;}}{x}_{\mathrm{set}}$

Wherein, z ₁for unit length electric transmission line positive sequence impedance; for imaginary part; for imaginary part; x _setfor line protection setting range; φ φ=AB, BC, CA phase.

Protective device judges that phase fault point meets 135 ° of < Arg [Δ z] < 225 ° to the phase angle Arg [Δ z] of the line fault impedance Δ z at line protection setting range place and whether sets up; if set up, then protective device sends action trip signal.

First the inventive method utilizes the fault voltage between phases of line protection installation place, between fault three-phase current and fault phase, negative sequence voltage calculates the line fault impedance of phase fault point to line protection setting range place; then judge that phase fault point drops in (135 ° 225 °) scope to the phase angle of the line fault impedance at line protection setting range place whether to set up; if set up, then protective device sends action trip signal.The inventive method can correct action message when the alternate high resistant short trouble of transmission line, overcomes transition resistance and load current to the impact of Perfomance of protective relaying, is applicable to the relaying protection of the whole failure process of electric transmission line phase fault.

The foregoing is only 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 change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.

Claims (1)

1. based on the line interphase fault relay protection method of fault impedance phase characteristic, it is characterized in that, comprise the steps:

(1) current waveform of protective device to the voltage waveform summation current transformer CT of the voltage transformer pt of line protection installation place carries out sampling and obtains voltage, current instantaneous value, as input variable; The voltage obtained sampling, current instantaneous value utilize Fourier algorithm computing electric power line to protect the fault voltage between phases of installation place fault three-phase current and negative sequence voltage between fault phase wherein, φ φ=AB, BC, CA phase;

(2) protective device utilizes the fault voltage between phases of line protection installation place fault three-phase current and negative sequence voltage between fault phase calculate the line fault impedance Δ z of phase fault point to line protection setting range place:

$\mathrm{\&Delta;z}=\frac{\mathrm{Im}\left[\frac{{\stackrel{\&CenterDot;}{U}}_{\mathrm{\&phi;\&phi;}}}{z_1{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;\&phi;}}}\right]}{\mathrm{Im}\left[\frac{{\stackrel{\&CenterDot;}{U}}_{\mathrm{\&phi;\&phi;}2}}{z_1{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;\&phi;}}{z}_1}\right]}\frac{{\stackrel{\&CenterDot;}{U}}_{\mathrm{\&phi;\&phi;}2}}{z_1}-{\stackrel{\&CenterDot;}{U}}_{\mathrm{\&phi;\&phi;}}+z_1{\stackrel{\&CenterDot;}{I}}_{\mathrm{\&phi;\&phi;}}{x}_{\mathrm{set}}$

Wherein, z ₁for unit length electric transmission line positive sequence impedance; for imaginary part; for imaginary part; x _setfor line protection setting range;

(3) protective device judges that phase fault point meets 135 ° of < Arg [Δ z] < 225 ° to the phase angle Arg [Δ z] of the line fault impedance Δ z at line protection setting range place and whether sets up; if set up, then protective device sends action trip signal.