CN103795041A - Power transmission line overload false operation prevention phase-to-phase distance backup protection method - Google Patents

Abstract

The invention relates to a power transmission line overload false operation prevention phase-to-phase distance backup protection method. The method comprises the steps that a fault phase-to-phase voltage, a fault phase-to-phase current and a fault phase-to-phase negative-sequence current at a power transmission line protective installation position are measured firstly, voltage drop along a power transmission line is calculated, the voltage drop along the power transmission line is subtracted from the fault phase-to-phase voltage at the power transmission line protective installation position to obtain voltage drop of phase-to-phase arc light at a phase-to-phase short-circuit fault point of the power transmission line, and then the voltage drop of the phase-to-phase arc light and a rated phase-to-phase voltage of the power transmission line are utilized to form a power transmission line phase-to-phase distance backup protection criterion. By means of the power transmission line overload false operation prevention phase-to-phase distance backup protection method, the power transmission line phase-to-phase distance backup protection criterion is formed by utilizing the amplitude characteristics of the voltage drop of the phase-to-phase arc light, motion performance is not affected by transition resistance, load current and operating modes of an electric power system, large-area power outage of a power grid caused by great shift of power grid tidal current due to phase-to-phase distance backup protection false operations under the condition of overload of the power transmission line is effectively prevented, and operation safety and stability of the power grid are reinforced.

Description

A kind of transmission line overload faulty action preventing phase spacing back-up protection method

Technical field

The present invention relates to Relay Protection Technology in Power System field, specifically relate to a kind of transmission line overload faulty action preventing phase spacing back-up protection method.

Background technology

Power frequency variation forms distance protection apart from protection by reaction operating voltage amplitude Sudden Changing Rate, and the method has the power system operation mode of being subject to affects the advantages such as little and anti-transition resistance ability is strong.But the operating voltage amplitude Sudden Changing Rate adopting due to the method only exists at the fault initial stage, cannot be used as the backup protection of voltage levels transmission line.

Impedance distance protection is positioned at protection zone apart from length with differentiation fault point according to measurement impedance magnitude faults and is still positioned at outside protection zone.Impedance distance protection is little owing to affected by power system operation mode and structural change, is total failure component for the electric parameters of computation and measurement impedance, is applicable to the line protection of whole failure process.

Tradition phase to phase impedance distance protection hypothesis phase fault is metallic short circuit fault; ratio calculation by phase-to phase fault voltage and phase-to phase fault electric current is measured impedance, and the distance of carrying out faults point according to measurement impedance magnitude is to determine whether to send action trip signal.In fact, in electric power system, except the metallicity phase fault of arteface, the transition resistance of actual phase fault point is also non-vanishing, and the additional impedance that transition resistance produces can have a strong impact on the performance of impedance distance protection.Impedance distance protection tripping when if the resistance sense that is the additional impedance that transition resistance produces easily causes in protection zone phase-to phase fault; If impedance distance protection generation surmounts when the capacitance-resistance that is the additional impedance that transition resistance produces easily causes phase-to phase fault the protection zone outside.

High/super/extreme pressure transmission line of alternation current is also often heavy load transmission line, and heavy load electric current can make impedance distance protection malfunction or tripping, and heavy load electric current can not be ignored the impact of impedance distance protection performance.Circuit fault-free in overload transmission of electricity situation; the measurement impedance of traditional distance protection is owing to being subject to overload current affects meeting substantial deviation actual measurement impedance; easily cause traditional distance protection misoperation; cause grid power blackout expanded range; thereby even cause a large amount of transfer of load to threaten circuit normally to move, caused huge potential safety hazard to power grid security.

Summary of the invention

The object of the invention is to overcome the deficiency that prior art exists, provide a kind of performance not affected by transition resistance, load current and power system operation mode, the transmission line phase spacing back-up protection method of the reliable faulty action preventing of transmission line overload.

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

A kind of transmission line overload faulty action preventing phase spacing back-up protection method, is characterized in that, comprises following sequential steps:

1) the fault voltage between phases of protector measuring line protection installation place

negative-sequence current between fault phase

with fault three-phase current

Wherein, φ φ is AB phase or BC phase or CA phase;

2) protective device computing electric power line is along line drop $\mathrm{\Δ}\stackrel{\·}{U}=\frac{\mathrm{Re}\left({\stackrel{\·}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)-\mathrm{Im}\left({\stackrel{\·}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)}{\mathrm{Re}\left({\stackrel{\·}{I}}_{\mathrm{\φ\φ}2}\right)\mathrm{Im}\left(z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)-\mathrm{Im}\left({\stackrel{\·}{I}}_{\mathrm{\φ\φ}2}\right)\mathrm{Re}\left(z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)}{z}_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}};$

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

for

real part; for

imaginary part; for

real part;

for

imaginary part;

for

imaginary part;

for

real part; φ φ is AB phase or BC phase or CA phase;

for fault voltage between phases;

for negative-sequence current between fault phase;

for fault three-phase current;

3) voltage drop on protective device computing electric power line inter-phase arc

4) protective device judgement

whether set up, if set up, judge in line protection setting range phase fault occurs, send action trip signal to the circuit breaker at transmission line two ends;

Wherein, k is tuning coefficient, and k is value in (0.050.1) scope;

for the specified voltage between phases of transmission line.

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

First the inventive method measures negative-sequence current between line protection installation place fault voltage between phases, fault three-phase current and fault phase; computing electric power line is along line drop; utilize line protection installation place fault voltage between phases to deduct transmission line and obtain the voltage drop on transmission line phase fault point place inter-phase arc along line drop, then utilize voltage drop and the specified voltage between phases of transmission line on inter-phase arc to form transmission line phase spacing backup protection criterion.The inventive method adopts lumped parameter modeling, and algorithm model is simple, and algorithm operation quantity is little, and program realizes easily, protection quick action.Voltage drop on the real-time computing electric power line phase fault point of the inventive method place inter-phase arc; utilize the voltage drop amplitude characteristic on inter-phase arc to form transmission line phase spacing backup protection criterion; performance is not subject to the impact of transition resistance, load current and power system operation mode; effectively prevent that under transmission line Overload, phase spacing backup protection misoperation causes the large transfer of electric network swim to cause the generation of electric grid large area power cut accident, strengthen safe operation of electric network stability.

Accompanying drawing explanation

Fig. 1 is the circuit transmission system schematic diagram of implementing method of the present invention;

In figure: PT is that voltage transformer, CT are current transformer.

Embodiment

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

Fig. 1 is the circuit transmission system schematic diagram of implementing method of the present invention; the current waveform of the voltage waveform summation current transformer CT of the voltage transformer pt of protective device to line protection installation place is sampled and is obtained voltage, current instantaneous value, and utilizes the fault voltage between phases of Fourier algorithm computing electric power line protection installation place

negative-sequence current between fault phase

with fault three-phase current

wherein, φ φ is AB phase or BC phase or CA phase.

Protective device computing electric power line is along line drop

$\mathrm{\Δ}\stackrel{\·}{U}=\frac{\mathrm{Re}\left({\stackrel{\·}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)-\mathrm{Im}\left({\stackrel{\·}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)}{\mathrm{Re}\left({\stackrel{\·}{I}}_{\mathrm{\φ\φ}2}\right)\mathrm{Im}\left(z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)-\mathrm{Im}\left({\stackrel{\·}{I}}_{\mathrm{\φ\φ}2}\right)\mathrm{Re}\left(z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)}{z}_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}$

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

for

real part;

for

imaginary part;

for

imaginary part;

for

real part;

for

imaginary part;

for

real part; φ φ is AB phase or BC phase or CA phase;

for fault voltage between phases;

for negative-sequence current between fault phase;

for fault three-phase current.

Voltage drop on protective device computing electric power line inter-phase arc

Utilize voltage drop and the specified voltage between phases formation transmission line phase spacing backup protection of transmission line criterion on inter-phase arc as follows: protective device judgement whether set up, if set up, judge in line protection setting range phase fault occurs, send action trip signal to the circuit breaker at transmission line two ends; Wherein, k is tuning coefficient, and k is value in (0.050.1) scope;

for the specified voltage between phases of transmission line.

First the inventive method measures negative-sequence current between line protection installation place fault voltage between phases, fault three-phase current and fault phase; computing electric power line is along line drop; utilize line protection installation place fault voltage between phases to deduct transmission line and obtain the voltage drop on transmission line phase fault point place inter-phase arc along line drop, then utilize voltage drop and the specified voltage between phases of transmission line on inter-phase arc to form transmission line phase spacing backup protection criterion.The inventive method adopts lumped parameter modeling, and algorithm model is simple, and algorithm operation quantity is little, and program realizes easily, protection quick action.Voltage drop on the real-time computing electric power line phase fault point of the inventive method place inter-phase arc; utilize the voltage drop amplitude characteristic on inter-phase arc to form transmission line phase spacing backup protection criterion; performance is not subject to the impact of transition resistance, load current and power system operation mode; effectively prevent that under transmission line Overload, phase spacing backup protection misoperation causes the large transfer of electric network swim to cause the generation of electric grid large area power cut accident, strengthen safe operation of electric network stability.

The foregoing is only preferred embodiment of the present invention; but protection scope of the present invention is not limited to this; any be familiar with those skilled in the art the present invention disclose technical scope in, the variation that can expect easily or replacement, within all should being encompassed in protection scope of the present invention.

Claims (1)

1. a transmission line overload faulty action preventing phase spacing back-up protection method, is characterized in that, comprises following sequential steps:

1) the fault voltage between phases of protector measuring line protection installation place

negative-sequence current between fault phase with fault three-phase current

Wherein, φ φ is AB phase or BC phase or CA phase;

2) protective device computing electric power line is along line drop $\mathrm{\Δ}\stackrel{\·}{U}=\frac{\mathrm{Re}\left({\stackrel{\·}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)-\mathrm{Im}\left({\stackrel{\·}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)}{\mathrm{Re}\left({\stackrel{\·}{I}}_{\mathrm{\φ\φ}2}\right)\mathrm{Im}\left(z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)-\mathrm{Im}\left({\stackrel{\·}{I}}_{\mathrm{\φ\φ}2}\right)\mathrm{Re}\left(z_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)}{z}_1{\stackrel{\·}{I}}_{\mathrm{\φ\φ}};$

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

for

real part;

for

imaginary part;

for real part;

for

imaginary part;

for

imaginary part;

for

real part; φ φ is AB phase or BC phase or CA phase; for fault voltage between phases;

for negative-sequence current between fault phase;

for fault three-phase current;

3) voltage drop on protective device computing electric power line inter-phase arc

4) protective device judgement

whether set up, if set up, judge in line protection setting range phase fault occurs, send action trip signal to the circuit breaker at transmission line two ends;

Wherein, k is tuning coefficient, and k is value in (0.050.1) scope;

for the specified voltage between phases of transmission line.

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