CN103311908A - Method for realizing relay protection of single-phase high-resistance earth fault of power transmission line by using single-ended current magnitude - Google Patents

Abstract

The invention discloses a method for realizing relay protection of a single-phase high-resistance earth fault of a power transmission line by using single-ended current magnitude. The method comprises the steps of measuring a fault phase current instantaneous value of each sampling moment at a current transformer mounting position of the power transmission line; selecting two adjacent cycle fault phase current sampling values to form a protection criterion; detecting the degree of asymmetry of the fault phase current waveform and the existence of a discontinuous region; judging whether the power transmission line has a single-phase high-resistance earth fault if the protection criterion is accepted; and sending an action tripping signal to trip breakers at the two ends of the power transmission line. According to the method, the relay protection of the single-phase high-resistance earth fault of the power transmission line is realized by using the single-ended current magnitude, the action performance is not affected by transition resistance and load current, and correct reliable action can be realized in case of single-phase high-resistance earth fault of the power transmission line. According to the method, only the single-ended current magnitude is required to be used, the voltage data is not required to be used, and the action performance is not affected by secondary loop breakage of a voltage transformer.

Description

Utilize single end current to realize the single-phase high resistance earthing fault relay protecting method of transmission line

Technical field

The present invention relates to the relay protection of power system technical field, specifically relate to a kind of single end current that utilizes and realize the single-phase high resistance earthing fault relay protecting method of transmission line.

Background technology

The additional impedance that transition resistance produces can have a strong impact on the performance of impedance distance protection.If impedance distance protection tripping when causing the line protection troubles inside the sample space easily that the additional impedance that transition resistance produces is resistance sense; If producing, impedance distance protection action that the additional impedance that transition resistance produces is capacitance-resistance when causing the line protection external area error easily surmounts.

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

Summary of the invention

The objective of the invention is to overcome the deficiency that prior art exists, provide a kind of single end current that utilizes to realize the single-phase high resistance earthing fault relay protecting method of transmission line.The inventive method is at first measured the fault phase current instantaneous value of each sampling instant of transmission line current transformer installation place; choose two adjacent cycle fault phase current sampling values and constitute the protection criterion; to fault phase current waveform degree of asymmetry with whether exist discontiguous area to detect; if the protection criterion is set up; judge that then single-phase high resistance earthing fault takes place transmission line; send the would trip signal, the circuit breaker at tripping transmission line two ends.The inventive method utilizes single end current to realize the relaying protection of the single-phase high resistance earthing fault of transmission line, and performance is not subjected to the influence of transition resistance and load current, can correct action message during the single-phase high resistance earthing fault of transmission line.The inventive method only need be utilized single end current, need not to use voltage data, and performance is not subjected to the influence of voltage transformer secondary circuit breaking.

For achieving the above object, the inventive method adopts following technical scheme:

Utilize single end current to realize the single-phase high resistance earthing fault relay protecting method of transmission line, it is characterized in that, comprise following sequential steps:

The fault phase current instantaneous value of each sampling instant of protector measuring transmission line current transformer installation place utilizes the fault phase current instantaneous value of its each sampling instant that measures to calculate $\underset{x=0}{\overset{N-1}{\mathrm{\Σ}}}i(t+\mathrm{x\Δt})>k\underset{x=0}{\overset{N-1}{\mathrm{\Σ}}}[i(t+\mathrm{x\Δt})+i(t+\mathrm{x\Δt}-\frac{N}{2}\mathrm{\Δt})]$ With $\underset{x=0}{\overset{N-1}{\mathrm{\Σ}}}i(t+\mathrm{x\Δt})>\mathrm{\β}{I}_e+\mathrm{\α}\underset{x=0}{\overset{N-1}{\mathrm{\Σ}}}[i(t+\mathrm{x\Δt})+i(t+\mathrm{x\Δt}-N\mathrm{\Δt})]$ Whether set up simultaneously, if set up simultaneously, judge that then single-phase high resistance earthing fault takes place transmission line, protective device sends the would trip signal, the circuit breaker at tripping transmission line two ends; Wherein, t is sampling instant; Δ t is the time in sampling interval; X is the positive integer counter; I (t+x Δ t) is the fault phase current sampling value of t+x Δ t sampling instant;

For

The fault phase current sampling value of sampling instant; I (t+x Δ t-N Δ t) is the fault phase current sampling value of t+x Δ t-N Δ t sampling instant; N is a cycle sampling number,

T is the cycle time of fundametal compoment; I _eBe the transmission line rated current; K is tuning coefficient; α is tuning coefficient; β is tuning coefficient.

Characteristics of the present invention and technological achievement:

The inventive method is at first measured the fault phase current instantaneous value of each sampling instant of transmission line current transformer installation place; choose two adjacent cycle fault phase current sampling values and constitute the protection criterion; to fault phase current waveform degree of asymmetry with whether exist discontiguous area to detect; if the protection criterion is set up; judge that then single-phase high resistance earthing fault takes place transmission line; send the would trip signal, the circuit breaker at tripping transmission line two ends.The inventive method utilizes single end current to realize the relaying protection of the single-phase high resistance earthing fault of transmission line, and performance is not subjected to the influence of transition resistance and load current, can correct action message during the single-phase high resistance earthing fault of transmission line.The inventive method only need be utilized single end current, need not to use voltage data, and performance is not subjected to the influence of voltage transformer secondary circuit breaking.

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.CT is current transformer among Fig. 1.The current instantaneous value of each sampling instant of protector measuring transmission line current transformer installation place utilizes the fault phase current instantaneous value of its each sampling instant that measures to calculate $\underset{x=0}{\overset{N-1}{\mathrm{\Σ}}}i(t+\mathrm{x\Δt})>k\underset{x=0}{\overset{N-1}{\mathrm{\Σ}}}[i(t+\mathrm{x\Δt})+i(t+\mathrm{x\Δt}-\frac{N}{2}\mathrm{\Δt})]$ With $\underset{x=0}{\overset{N-1}{\mathrm{\Σ}}}i(t+\mathrm{x\Δt})>\mathrm{\β}{I}_e+\mathrm{\α}\underset{x=0}{\overset{N-1}{\mathrm{\Σ}}}[i(t+\mathrm{x\Δt})+i(t+\mathrm{x\Δt}-N\mathrm{\Δt})]$ Whether set up simultaneously, if set up simultaneously, judge that then single-phase high resistance earthing fault takes place transmission line, protective device sends the would trip signal, the circuit breaker at tripping transmission line two ends.

Wherein, t is sampling instant; Δ t is the time in sampling interval; X is the positive integer counter; I (t+x Δ t) is the fault phase current sampling value of t+x Δ t sampling instant; For

The fault phase current sampling value of sampling instant; I (t+x Δ t-N Δ t) is the fault phase current sampling value of t+x Δ t-N Δ t sampling instant; N is a cycle sampling number,

T is the cycle time of fundametal compoment; I _eBe the transmission line rated current; K is tuning coefficient; α is tuning coefficient; β is tuning coefficient.

The inventive method is at first measured the fault phase current instantaneous value of each sampling instant of transmission line current transformer installation place; choose two adjacent cycle fault phase current sampling values and constitute the protection criterion; to fault phase current waveform degree of asymmetry with whether exist discontiguous area to detect; if the protection criterion is set up; judge that then single-phase high resistance earthing fault takes place transmission line; send the would trip signal, the circuit breaker at tripping transmission line two ends.The inventive method utilizes single end current to realize the relaying protection of the single-phase high resistance earthing fault of transmission line, and performance is not subjected to the influence of transition resistance and load current, can correct action message during the single-phase high resistance earthing fault of transmission line.The inventive method only need be utilized single end current, need not to use voltage data, and performance is not subjected to the influence of voltage transformer secondary circuit breaking.

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. utilize single end current to realize the single-phase high resistance earthing fault relay protecting method of transmission line, it is characterized in that, comprise following sequential steps:

The fault phase current instantaneous value of each sampling instant of protector measuring transmission line current transformer installation place utilizes the fault phase current instantaneous value of its each sampling instant that measures to calculate $\underset{x=0}{\overset{N-1}{\mathrm{\Σ}}}i(t+\mathrm{x\Δt})>k\underset{x=0}{\overset{N-1}{\mathrm{\Σ}}}[i(t+\mathrm{x\Δt})+i(t+\mathrm{x\Δt}-\frac{N}{2}\mathrm{\Δt})]$ With $\underset{x=0}{\overset{N-1}{\mathrm{\Σ}}}i(t+\mathrm{x\Δt})>\mathrm{\β}{I}_e+\mathrm{\α}\underset{x=0}{\overset{N-1}{\mathrm{\Σ}}}[i(t+\mathrm{x\Δt})+i(t+\mathrm{x\Δt}-N\mathrm{\Δt})]$ Whether set up simultaneously, if set up simultaneously, judge that then single-phase high resistance earthing fault takes place transmission line, protective device sends the would trip signal, the circuit breaker at tripping transmission line two ends; Wherein, t is sampling instant; Δ t is the time in sampling interval; X is the positive integer counter; I (t+x Δ t) is the fault phase current sampling value of t+x Δ t sampling instant; For

The fault phase current sampling value of sampling instant; I (t+x Δ t-N Δ t) is the fault phase current sampling value of t+x Δ t-N Δ t sampling instant; N is a cycle sampling number, T is the cycle time of fundametal compoment; I _eBe the transmission line rated current; K is tuning coefficient; α is tuning coefficient; β is tuning coefficient.

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