CN103296651A - Interphase fault distance protecting method for overload maloperation-preventive and anti-high-resistance lines - Google Patents

Abstract

The invention discloses an interphase fault distance protecting method for overload maloperation-preventive and anti-high-resistance lines. The interphase fault distance protecting method includes: firstly utilizing fault interphase voltage, fault interphase current and fault interphase negative-sequence current at a power transmission line protection installation point to calculate line distance between the power transmission line protection setting range to an interphase short-circuit fault point, judging whether the line distance between the power transmission line protection setting range to the interphase short-circuit fault point is larger than zero or not, if yes, judging that the interphase short-circuit fault point is within the power transmission line protection setting range, and sending out an action trip signal to trip off breakers at two ends of the power transmission line. By the interphase fault distance protecting method, influence on protective action performance from transition resistance is eliminated theoretically, and strong resistance to affection of the transition resistance is provided.

Description

The circuit phase-to phase fault distance protecting method of overload faulty action preventing and anti-high resistant

Technical field

The present invention relates to the relay protection of power system technical field, specifically relate to the circuit phase-to phase fault distance protecting method of a kind of overload faulty action preventing and anti-high resistant.

Background technology

Distance protection is little owing to influenced by power system operation mode and structural change, can moment selectively excise the various faults of transmission line, obtains extensive use in the power system transmission line protection.Distance protection is used as the transmission line main protection on the ultra-high-tension power transmission line, and distance protection is used as the transmission line backup protection on the ultra-high/extra-high voltage transmission line of alternation current.The distance protection of power system transmission line extensive use at present comprises that mainly power frequency variation is apart from protection and impedance distance protection.

Power frequency variation constitutes distance protection apart from protection by reaction operating voltage amplitude sudden change amount, and this method has the power system operation mode of being subjected to influences advantages such as little and anti-transition resistance ability is strong.But because the operating voltage amplitude sudden change amount that this method adopts only exists at the fault initial stage, can't be used as the backup protection of ultra-high/extra-high voltage transmission line of alternation current.

The impedance distance protection is positioned at the protection zone according to measurement impedance magnitude reflection fault distance length with the differentiation fault point or is positioned at outside the protection zone.The impedance distance protection is little owing to influenced by power system operation mode and structural change, and being used for calculating the electric parameters of measuring impedance is the total failure component, is applicable to whole failure process.Therefore, the impedance distance protection both can be used for the ultra-high-tension power transmission line main protection, also can be used as the backup protection of ultra-high/extra-high voltage transmission line of alternation current.

If yet impedance distance protection performance is influenced seriously by transition resistance, mainly shows as the additional impedance that transition resistance produces is resistance sense impedance distance protection tripping when causing the line protection troubles inside the sample space easily; 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.

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.Transmission line 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 and cause the grid power blackout expanded range; even cause big transfer of load to threaten other transmission lines normally to move, bring 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, the circuit phase-to phase fault distance protecting method of a kind of overload faulty action preventing and anti-high resistant is provided.

The circuit phase-to phase fault distance protecting method of overload faulty action preventing and anti-high resistant is characterized in that, comprises following sequential steps:

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

, the fault three-phase current

Alternate negative-sequence current with fault

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

(2) protective device computing electric power line protection setting range place arrives the circuit distance, delta x of phase fault point:

$\mathrm{\Δx}=\left|\frac{{\stackrel{.}{U}}_{\mathrm{\φ\φ}}-z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}{x}_{\mathrm{set}}}{z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\sin (\mathrm{\β}+\mathrm{\γ})}\right|\sin \mathrm{\α}$

Wherein, z ₁Be unit length transmission line positive sequence impedance; x _SetBe the line protection setting range; β=Arg (z ₁) be unit length transmission line positive sequence impedance z ₁Phase angle;

For

Leading

Angle;

For

Leading

Angle; φ φ=AB, BC, CA phase;

(3) protective device judges that whether line protection setting range place arrives the circuit distance, delta x of phase fault point greater than zero, if line protection setting range place arrives the circuit distance, delta x of phase fault point greater than zero, judge that then the phase fault point is positioned within the line protection setting range, protective device sends the would trip signal, the circuit breaker at tripping transmission line two ends; Otherwise, if line protection setting range place arrives the circuit distance, delta x of phase fault point less than zero, judge that then the phase fault point is positioned at outside the line protection setting range, protective device sends block signal.

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

The inventive method at first computing electric power line protects the setting range place to the circuit distance of phase fault point; judge that then whether line protection setting range place arrives the circuit distance of phase fault point greater than zero; if line protection setting range place arrives the circuit distance of phase fault point greater than zero; judge that then the phase fault point is positioned within the line protection setting range; send the would trip signal, the circuit breaker at tripping transmission line two ends.Eliminate the influence of transition resistance to the protection performance on the inventive method principle, had the ability of very strong anti-transition resistance influence.Eliminated the influence of load current to the protection performance on the inventive method principle; the inventive method performance is reliable and stable during transmission line heavy service; misoperation can not take place; power network safety operation is guaranteed in the generation of power grid cascading tripping operation accident in the time of preventing effectively that electric network swim is big and shift.

Description of drawings

Fig. 1 is for using circuit transmission system schematic diagram of the present invention.

Embodiment

Below in conjunction with embodiment technical scheme of the present invention is done further detailed presentations.

Fig. 1 is for using circuit transmission system schematic diagram of the present invention.CVT is that voltage transformer, CT are current transformer among Fig. 1.Protective device is sampled to the current waveform of the voltage and current instrument transformer CT of the voltage transformer CVT of line protection installation place and is obtained voltage, current instantaneous value, and protective device utilizes the fault voltage between phases of Fourier algorithm computing electric power line protection installation place to its voltage that collects, current instantaneous value then , the fault three-phase current

Alternate negative-sequence current with fault

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

Protective device computing electric power line protection setting range place arrives the circuit distance, delta x of phase fault point:

$\mathrm{\Δx}=\left|\frac{{\stackrel{.}{U}}_{\mathrm{\φ\φ}}-z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}{x}_{\mathrm{set}}}{z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\sin (\mathrm{\β}+\mathrm{\γ})}\right|\sin \mathrm{\α}$

Wherein, z ₁Be unit length transmission line positive sequence impedance; x _SetBe the line protection setting range; β=Arg (z ₁) be unit length transmission line positive sequence impedance z ₁Phase angle;

For

Leading

Angle;

For

Leading

Angle; φ φ=AB, BC, CA phase.

Protective device judges that whether line protection setting range place arrives the circuit distance, delta x of phase fault point greater than zero, if line protection setting range place arrives the circuit distance, delta x of phase fault point greater than zero, judge that then the phase fault point is positioned within the line protection setting range, protective device sends the would trip signal, the circuit breaker at tripping transmission line two ends; Otherwise, if line protection setting range place arrives the circuit distance, delta x of phase fault point less than zero, judge that then the phase fault point is positioned at outside the line protection setting range, protective device sends block signal.

Eliminate the influence of transition resistance to the protection performance on the inventive method principle, had the ability of very strong anti-transition resistance influence.Eliminated the influence of load current to the protection performance on the inventive method principle; the inventive method performance is reliable and stable during transmission line heavy service; misoperation can not take place; power network safety operation is guaranteed in the generation of power grid cascading tripping operation accident in the time of preventing effectively that electric network swim is big and shift.

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. the circuit phase-to phase fault distance protecting method of overload faulty action preventing and anti-high resistant is characterized in that, comprises following sequential steps:

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

, the fault three-phase current

Alternate negative-sequence current with fault

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

(2) protective device computing electric power line protection setting range place arrives the circuit distance, delta x of phase fault point:

$\mathrm{\Δx}=\left|\frac{{\stackrel{.}{U}}_{\mathrm{\φ\φ}}-z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}{x}_{\mathrm{set}}}{z_1{\stackrel{.}{I}}_{\mathrm{\φ\φ}}\sin (\mathrm{\β}+\mathrm{\γ})}\right|\sin \mathrm{\α}$

Wherein, z ₁Be unit length transmission line positive sequence impedance; x _SetBe the line protection setting range; β=Arg (z ₁) be unit length transmission line positive sequence impedance z ₁Phase angle;

For

Leading

Angle;

For

Leading

Angle; φ φ=AB, BC, CA phase;

(3) protective device judges that whether line protection setting range place arrives the circuit distance, delta x of phase fault point greater than zero, if line protection setting range place arrives the circuit distance, delta x of phase fault point greater than zero, judge that then the phase fault point is positioned within the line protection setting range, protective device sends the would trip signal, the circuit breaker at tripping transmission line two ends; Otherwise, if line protection setting range place arrives the circuit distance, delta x of phase fault point less than zero, judge that then the phase fault point is positioned at outside the line protection setting range, protective device sends block signal.

Images