CN103107524B - Electric transmission line phase fault relay protection method - Google Patents

Abstract

The invention discloses an electric transmission line phase fault relay protection method which serves as a measuring element of measurement impedance of electric transmission line phase fault distance protection. The measurement impedance from a phase fault point to the protection installation portion can be measured accurately in any fault condition, which has no reference to phase fault point voltage, a load current and transition resistance. The method is closed reliably under the condition of heavy loading of an electric transmission line. Requirements of selectivity, reliability, sensitivity and quick-action performance of relay protection can be met through correct movement of the method when a phase high resistance short trouble happens under the condition of heavy loading electricity transmission.

Description

A kind of electric transmission line phase fault relay protection method

Technical field

The present invention relates to Relay Protection Technology in Power System field, particularly a kind of electric transmission line phase fault relay protection method.

Background technology

The protection of power frequency variation distance forms distance protection by reaction operating voltage amplitude Sudden Changing Rate, and the method has affects the advantages such as little and anti-transition resistance ability is strong by power system operation mode.But the operating voltage amplitude Sudden Changing Rate adopted due to the method only exists at the fault initial stage, cannot be used as the back-up protection of ultra-high/extra-high voltage transmission line of alternation current.

Impedance distance protection is positioned at protected location according to measurement impedance size faults distance length is still positioned at outside protected location to distinguish trouble spot.Impedance distance protection due to by power system operation mode and structural change little, the electric parameters for computation and measurement impedance is total failure component, is applicable to the line protection of whole failure process.Therefore, impedance distance protection both can be used for ultra-high-tension power transmission line main protection, also can be used as the back-up protection of ultra-high/extra-high voltage transmission line of alternation current.

Tradition phase to phase impedance distance protection hypothesis phase-to phase fault point voltage is zero, and by the ratio calculation measurement impedance of phase-to phase fault voltage and phase-to phase fault electric current, and the distance carrying out faults point according to measurement impedance size is to determine whether send trip signal.In fact, in electric system, except the metallicity phase fault of arteface, phase-to phase fault point voltage may be zero hardly.Therefore, phase-to phase fault point voltage can cause serious impact to phase distance protection performance.

In practical power systems, by transition resistance bring additional impedance can have a strong impact on the performance of impedance distance protection.If phase to phase impedance distance protection tripping when easily causing phase fault in protected location that the additional impedance that transition resistance produces is resistance sense; If the additional impedance that transition resistance produces be capacitance-resistance when easily causing phase fault outside protected location, phase to phase impedance distance protection action generation surmounts.High/super/extreme pressure transmission line of alternation current is also often heavy load transmission line of electricity, heavy load electric current can make impedance distance protection malfunction, and the impact of heavy load electric current on impedance distance protection performance can not be ignored.

Summary of the invention

The object of the invention is to the deficiency overcoming prior art existence, a kind of electric transmission line phase fault relay protection method is provided.The method can realize the accurate measurement function of the measurement impedance of electric transmission line phase fault distance protection.

A kind of electric transmission line phase fault relay protection method, its step is as follows:

(1) the fault voltage between phases of line protection installation place is measured fault three-phase current with normal phase negative-sequence current wherein φ φ is respectively AB phase or BC phase or CA phase; Ψ corresponds to C phase or A phase or B phase respectively.

(2) the measurement impedance Z of phase fault point to line protection installation place is calculated _{φ φ, ce}:

$Z_{\mathrm{\φ\φ},\mathrm{ce}}=(x_{\mathrm{set}}-|\frac{{\stackrel{\·}{U}}_{\mathrm{\φ\φ}}-x_{\mathrm{set}}{z}_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}}{z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\sin (\mathrm{\β}+\mathrm{\γ})}\left|\right)z_1$

Wherein, for fault voltage between phases; for fault three-phase current; for normal phase negative-sequence current; φ φ is respectively AB phase or BC phase or CA phase; Ψ corresponds to C phase or A phase or B phase respectively; x _setfor protection seting scope;

z1 is unit length electric transmission line positive sequence impedance; represent normal phase negative-sequence current through being rotated counterclockwise the electric current phasor after 90 °.

(3) judge | Z _{φ φ, ce}-Z _set|≤| Z _{φ φ, ce}+ Z _set| whether set up, if | Z _{φ φ, ce}-Z _set|≤| Z _{φ φ, ce}+ Z _set| set up, then protection act is in tripping operation; Wherein, Z _setfor protection seting resistance value, if | Z _{φ φ, c}e-Z _set| > | Z _{φ φ, ce}+ Z _set|, then protection blocking.

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

The inventive method is measured phase fault point and is had nothing to do to the measurement impedance of line protection installation place and phase-to phase fault point voltage, transition resistance and load current; the reliable locking of the inventive method in transmission line of electricity heavy load situation, the reliable correct operation of the inventive method when alternate high resistant short trouble occurs heavy load transmission of electricity situation line.

Accompanying drawing explanation

Fig. 1 is the electric transmission line phase fault schematic diagram of application the inventive method.

Fig. 2 is the electric transmission line phase fault of application the inventive method with electric vector graph of a relation.

Embodiment

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

In Fig. 1, PT is voltage transformer (VT), CT is current transformer.The current waveform of protective device to the potential and current transformers CT of the voltage transformer pt of line protection installation place carries out sampling and obtains voltage, current instantaneous value.

By Fourier algorithm computing electric power line protection installation place fault phase between voltage phasor electric current phasor between fault phase normal phase negative-sequence current phasor as input quantity; Wherein, φ φ is fault phase, is respectively AB phase or BC phase or CA phase; Ψ is normal phase, corresponds to C phase or A phase or B phase respectively.

Transmission line of electricity occurs alternate with transition resistance Rf short trouble, phase-to phase fault point voltage fault branch electric current because resistive phase fault, has at fault branch thus Arg

Transmission line of electricity occurs alternate with transition resistive short fault, has at fault branch thus wherein, be respectively the forward-order current, the negative-sequence current that flow through fault branch; for the trouble spot negative-sequence current over the ground of normal phase Ψ; for through being rotated counterclockwise the electric current phasor after 90 °.

Transmission line of electricity occurs alternate with transition resistive short fault, the normal phase negative-sequence current that protection installation place measures with normal phase trouble spot negative-sequence current over the ground same-phase, namely $\mathrm{Arg}\left({\stackrel{\·}{I}}_{\mathrm{\Ψ}2}\right)=\mathrm{Arg}\left({\stackrel{\·}{I}}_{\mathrm{\Ψf}2}\right).$ So, obtain $\mathrm{Arg}\left({\stackrel{\·}{U}}_{\mathrm{\φ\φf}}\right)=\mathrm{Arg}\left(j{\stackrel{\·}{I}}_{\mathrm{\Ψ}2}\right).$ Wherein, represent normal phase negative-sequence current through being rotated counterclockwise the electric current phasor after 90 °.

Calculate the operating voltage apart from protection xt position, installation place

${\stackrel{\·}{U}}_{\mathrm{\φ\φ},\mathrm{set}}={\stackrel{\·}{U}}_{\mathrm{\φ\φ}}-x_{\mathrm{set}}{z}_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}---\left(1\right)$

Wherein, z ₁for unit length electric transmission line positive sequence impedance.

Transmission line of electricity to occur alternate with transition resistive short fault with electric vector relation as shown in Figure 2.In fig. 2, by with in the vector triangle formed, obtain formula (2) relation according to triangle edges angular dependence.

$x_{\mathrm{set}}-x=\left|\frac{{\stackrel{\·}{U}}_{\mathrm{\φ\φ}}-x_{\mathrm{set}}{z}_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}}{z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\sin (\mathrm{\β}+\mathrm{\γ})}\right|\sin \mathrm{\α}---\left(2\right)$

Wherein: $\mathrm{\β}=\mathrm{Arg}\left(z_1\right);\mathrm{\α}=\mathrm{Arg}\left(\frac{j{\stackrel{\·}{I}}_{\mathrm{\Ψ}2}}{{\stackrel{\·}{U}}_{\mathrm{\φ\φ}}-x_{\mathrm{set}}{z}_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}}\right);\mathrm{\γ}=\mathrm{Arg}\left(\frac{{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}}{j{\stackrel{\·}{I}}_{\mathrm{\Ψ}2}}\right).$

The fault distance calculating formula (3) of phase fault point to line protection installation place can be obtained by formula (2).

$x=x_{\mathrm{set}}-\left|\frac{{\stackrel{\·}{U}}_{\mathrm{\φ\φ}}-x_{\mathrm{set}}{z}_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}}{z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\sin (\mathrm{\β}+\mathrm{\γ})}\right|\sin \mathrm{\α}---\left(3\right)$

According to measurement impedance Z _{φ φ, ce}=xz ₁computation and measurement impedance $Z_{\mathrm{\φ\φ},\mathrm{ce}}=(x_{\mathrm{set}}-|\frac{{\stackrel{\·}{U}}_{\mathrm{\φ\φ}}-x_{\mathrm{set}}{z}_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}}{z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\sin (\mathrm{\β}+\mathrm{\γ})}\left|\sin \mathrm{\α}\right)z_1.$

Judge | Z _{φ φ, ce}-Z _set|≤| Z _{φ φ, ce}+ Z _set| whether set up.If | Z _{φ φ, ce}-Z _set|≤| Z _{φ φ, ce}+ Z _set| set up, then protection act is in tripping operation; Otherwise, if meet | Z _{φ φ, ce}-Z _set| > | Z _{φ φ, ce}+ Z _set|, then protection blocking.

From formula (3), the measurement impedance of the phase fault distance protection of the inventive method and phase-to phase fault point voltage, transition resistance and load current have nothing to do.Therefore; the measurement impedance of phase-to phase fault point to protection installation place accurately can be measured under the inventive method what fault condition in office; the reliable locking of the inventive method in transmission line of electricity heavy load situation, the reliable correct operation of the inventive method when heavy load transmission of electricity situation issues high resistant short trouble between looks.

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. an electric transmission line phase fault relay protection method, is characterized in that: comprise the steps,

(1) the fault voltage between phases of line protection installation place is measured fault three-phase current with normal phase negative-sequence current wherein φ φ is respectively AB phase or BC phase or CA phase; Ψ corresponds to C phase or A phase or B phase respectively,

(2) the measurement impedance Z of phase fault point to line protection installation place is calculated _{φ φ, ce}:

$Z_{\mathrm{\φ\φ},\mathrm{ce}}=(x_{\mathrm{set}}-|\frac{{\stackrel{\·}{U}}_{\mathrm{\φ\φ}}-x_{\mathrm{set}}{z}_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}}{z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\sin (\mathrm{\β}+\mathrm{\γ})}\left|\sin \mathrm{\α}\right)z_1$

Wherein, for fault voltage between phases; for fault three-phase current; for normal phase negative-sequence current; φ φ is respectively AB phase or BC phase or CA phase; Ψ corresponds to C phase or A phase or B phase respectively; x _setfor protection seting scope; β=Arg (z ₁); z ₁for unit length electric transmission line positive sequence impedance; represent normal phase negative-sequence current through being rotated counterclockwise the electric current phasor after 90 °,

(3) judge | Z _{φ φ, ce}-Z _set|≤| Z _{φ φ, ce}+ Z _set| whether set up, if | Z _{φ φ, ce}-Z _set|≤| Z _{φ φ, ce}+ Z _set| set up, then protection act is in tripping operation; Wherein, Z _setfor protection seting resistance value; If | Z _{φ φ, ce}-Z _set| > | Z _{φ φ, ce}+ Z _set|, then protection blocking.