CN103219715A - Line inter-phase fault relay protection method based on fault impedance phase characteristics - Google Patents

Abstract

The invention discloses a line inter-phase fault relay protection method based on fault impedance phase characteristics. Fault inter-phase voltage, fault inter-phase current and fault inter-phase negative-sequence current of a transmission line protection and installation portion are utilized to calculate line fault impedance from an inter-phase short circuit fault point to a transmission line protection setting range, whether an phase angle from the inter-phase short circuit fault point to the transmission line protection setting range is within the range of 135 degrees to 225 degrees or not is judged. If the phase angle is within the range of135 degrees to 225 degree, a protection device sends out motion trip signals. The method can be carried out in a transmission line inter-phase high resistance short circuit fault, eliminates influences of transition resistance and load current on protection motion performance, and is suitable for relay protection of whole fault process of transmission line inter-phase short circuit faults.

Description

Circuit phase-to phase fault relay protecting method based on the fault impedance phase characteristic

Technical field

The present invention relates to the relay protection of power system technical field, specifically relate to a kind of circuit phase-to phase fault relay protecting method based on the fault impedance phase characteristic.

Background technology

The tradition phase distance protection utilizes the ratio calculation line fault impedance of fault voltage between phases and fault three-phase current

, because , therefore

Thereby can get, 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, the additional fault impedance of another part for causing because of transition resistance

Wherein,

Be the fault voltage between phases;

Be the phase fault point voltage;

Be the fault three-phase current; R _fBe transition resistance;

Electric current for the phase fault point of flowing through; φ φ=AB, BC, CA phase; z ₁Be unit length transmission line positive sequence impedance; X is the fault distance of line protection installation place to phase fault point.

The additional fault impedance meeting that transition resistance produces causes traditional phase distance protection tripping or malfunction, and traditional phase distance protection tripping meeting makes the fault can not be in time and the electrical network isolation, and is unfavorable to power grid operation; The malfunction of tradition phase distance protection then can cause fault coverage to enlarge, even causes the big transfer of electric network swim, and then causes the generation of electric grid large area power cut accident.

Summary of the invention

The objective of the invention is to overcome the deficiency that prior art exists, the circuit phase-to phase fault relay protecting method that provides a kind of performance not influenced by transition resistance and load current based on the fault impedance phase characteristic.

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

(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 voltage between phases of Fourier algorithm computing electric power line protection installation place

, the fault three-phase current

Alternate negative sequence voltage with fault , as input variable; Wherein, φ φ=AB, BC, CA phase;

(2) protective device utilizes the fault voltage between phases of line protection installation place

, the fault three-phase current

Alternate negative sequence voltage with fault

Calculate phase fault and put the line fault impedance Δ z at 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 ₁Be unit length transmission line positive sequence impedance;

For

Imaginary part;

For

Imaginary part; x _SetBe the line protection setting range; φ φ=AB, BC, CA phase;

(3) protective device judges that phase fault puts the phase angle Arg[Δ z of the line fault impedance Δ z at line protection setting range place] satisfy 135 °＜Arg[Δ z]＜225 ° whether set up, if set up, then protective device sends the would trip signal.

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

The inventive method at first utilizes the alternate negative sequence voltage with fault of fault voltage between phases, the fault three-phase current of line protection installation place to calculate the line fault impedance that phase fault is put line protection setting range place; judge that then phase fault puts the phase angle of the line fault impedance at line protection setting range place and drop in (135 ° 225 °) scope and whether set up; if set up, then protective device sends the would trip signal.The inventive method can correct action message when the alternate high resistant short trouble of transmission line, has overcome the influence to the protection performance of transition resistance and load current, is applicable to the relaying protection of the whole failure process of transmission line phase fault.

Description of drawings

Fig. 1 is for using circuit transmission system schematic 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 schematic diagram of the present invention.PT is that voltage transformer, 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 voltage between phases of Fourier algorithm computing electric power line protection installation place

, the fault three-phase current Alternate negative sequence voltage with fault , as input variable; Wherein, φ φ=AB, BC, CA phase.

Protective device utilizes the fault voltage between phases of line protection installation place

, the fault three-phase current Alternate negative sequence voltage with fault Calculate phase fault and put the line fault impedance Δ z at 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 ₁Be unit length transmission line positive sequence impedance;

For

Imaginary part;

For

Imaginary part; x _SetBe the line protection setting range; φ φ=AB, BC, CA phase.

Protective device judges that phase fault puts the phase angle Arg[Δ z of the line fault impedance Δ z at line protection setting range place] satisfy 135 °＜Arg[Δ z]＜225 ° whether set up, if set up, then protective device sends the would trip signal.

The inventive method at first utilizes the alternate negative sequence voltage with fault of fault voltage between phases, the fault three-phase current of line protection installation place to calculate the line fault impedance that phase fault is put line protection setting range place; judge that then phase fault puts the phase angle of the line fault impedance at line protection setting range place and drop in (135 ° 225 °) scope and whether set up; if set up, then protective device sends the would trip signal.The inventive method can correct action message when the alternate high resistant short trouble of transmission line, has overcome the influence to the protection performance of transition resistance and load current, is applicable to the relaying protection of the whole failure process of transmission line phase fault.

The above only is a 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. based on the circuit phase-to phase fault relay protecting method of fault impedance phase characteristic, it is characterized in that, comprise the steps:

(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 voltage between phases of Fourier algorithm computing electric power line protection installation place

, the fault three-phase current

Alternate negative sequence voltage with fault

, as input variable; Wherein, φ φ=AB, BC, CA phase;

(2) protective device utilizes the fault voltage between phases of line protection installation place

, the fault three-phase current

Alternate negative sequence voltage with fault Calculate phase fault and put the line fault impedance Δ z at 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 ₁Be unit length transmission line positive sequence impedance;

For

Imaginary part;

For

Imaginary part; x _SetBe the line protection setting range;

(3) protective device judgement phase fault is put the phase angle Arg[Δ z of the line fault impedance Δ z at line protection setting range place]

Satisfy 135 °＜Arg[Δ z]＜225 ° whether set up, if set up, then protective device sends the would trip signal.

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