CN103296644A - Composite sequence component voltage protection method of power transmission line - Google Patents

Abstract

The invention discloses a composite sequence component voltage protection method of a power transmission line. The method includes computing fault impedance and voltage drop amplitude from a power transmission line protection mounting position to a single-phase ground fault point according to the principle that an equivalent positive-sequence voltage break variable is equal to a zero-sequence voltage of the single-phase ground fault point of the power transmission line, computing voltage drop amplitude from the power transmission line protection mounting position to a power transmission line protection, setting range position, and judging whether the voltage drop amplitude from the power transmission line protection mounting position to the single-phase ground fault point is lower than the voltage drop amplitude from the power transmission line protection mounting position to the power transmission line setting range position or not for action. Single-phase ground fault voltage protection is achieved by the aid of voltage distribution characteristics along the power transmission line, influences of transition resistance on protection action performance are eliminated in principle, action performance is unaffected by load current and fault location, and the method is applicable to relay protection within a two-cycle-wave time after single-phase ground faults of the power transmission line.

Description

The guard method of the compound order component voltage of transmission line

Technical field

The present invention relates to the relay protection of power system technical field, specifically relate to the guard method of the compound order component voltage of a kind of transmission line.

Background technology

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 guard method of the compound order component voltage of the transmission line that provides a kind of performance not influenced by transition resistance, abort situation and load current.

The guard method of the compound order component voltage of transmission line is characterized in that, comprises following sequential steps:

(1) the fault phase current of protector measuring line protection installation place

, positive sequence voltage sudden change amount

, fault phase forward-order current sudden change amount

, residual voltage

And zero-sequence current Wherein, φ=A phase, B phase, C phase;

(2) protective device computing electric power line protection installation place is to the fault impedance Z of single phase ground fault point _φ:

$Z_{\mathrm{\φ}}=\frac{(z_1+z_0){\stackrel{.}{U}}_0+z_0\mathrm{\Δ}{\stackrel{.}{U}}_{\mathrm{\φ}1}}{(z_1+z_0)z_0{\stackrel{.}{I}}_0+z_1{z}_0\mathrm{\Δ}{\stackrel{.}{I}}_{\mathrm{\φ}1}}{z}_1$

Wherein, φ=A phase, B phase, C phase; z ₁Be unit length transmission line positive sequence impedance; z ₀Be unit length transmission line zero sequence impedance; Be fault phase positive sequence voltage sudden change amount;

Be fault phase forward-order current sudden change amount;

Be residual voltage;

Be zero-sequence current;

(3) protective device is judged $\left|Z_{\mathrm{\&phi;}}({\stackrel{.}{I}}_{\mathrm{\&phi;}}+\frac{z_0-z_1}{z_1}{\stackrel{.}{I}}_0)\right|<\left|x_{\mathrm{set}}({\stackrel{.}{I}}_{\mathrm{\&phi;}}+\frac{z_0-z_1}{z_1}{\stackrel{.}{I}}_0)z_1\right|$ Whether set up, if set up, then protective device sends the would trip signal, the circuit breaker at tripping φ phase transmission line two ends; Wherein, φ=A phase, B phase, C phase; x _SetBe the line protection setting range.

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

The inventive method equates with residual voltage that according to the equivalent positive sequence voltage sudden change amount of transmission line one-phase earth fault point principle computing electric power line protection installation place is to the fault impedance of single phase ground fault point; computing electric power line protection installation place is to the voltage drop amplitude of single phase ground fault point; computing electric power line protection installation place is to the voltage drop amplitude at line protection setting range place; judge whether the line protection installation place sets up to the voltage drop amplitude at line protection setting range place less than the line protection installation place to the voltage drop amplitude of single phase ground fault point; if set up; judge that then the single phase ground fault point is positioned at the line protection setting range; send the would trip signal, the circuit breaker at tripping fault phase circuit two ends.The inventive method utilizes transmission line voltage distribution character along the line to realize the transmission line one-phase earth fault voltage protection; eliminated the influence of transition resistance to the protection performance on the principle; performance is not subjected to the influence of load current and abort situation, is applicable to the relaying protection in the two cycle times behind the transmission line one-phase earth fault.

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 phase current of Fourier algorithm computing electric power line protection installation place to its voltage that collects, current instantaneous value then

, positive sequence voltage sudden change amount

, fault phase forward-order current sudden change amount

, residual voltage

And zero-sequence current

Wherein, φ=A phase, B phase, C phase.

Protective device computing electric power line protection installation place is to the fault impedance Z of single phase ground fault point _φ:

$Z_{\mathrm{\&phi;}}=\frac{(z_1+z_0){\stackrel{.}{U}}_0+z_0\mathrm{\&Delta;}{\stackrel{.}{U}}_{\mathrm{\&phi;}1}}{(z_1+z_0)z_0{\stackrel{.}{I}}_0+z_1{z}_0\mathrm{\&Delta;}{\stackrel{.}{I}}_{\mathrm{\&phi;}1}}{z}_1$

Wherein, φ=A phase, B phase, C phase; z ₁Be unit length transmission line positive sequence impedance; z ₀Be unit length transmission line zero sequence impedance;

Be fault phase positive sequence voltage sudden change amount; Be fault phase forward-order current sudden change amount;

Be residual voltage;

Be zero-sequence current.

Protective device computing electric power line protection installation place is to the voltage drop amplitude of single phase ground fault point

Protective device computing electric power line protection installation place is to the voltage drop amplitude at line protection setting range place

Wherein, x _SetBe the line protection setting range.

Protective device is judged $\left|Z_{\mathrm{\&phi;}}({\stackrel{.}{I}}_{\mathrm{\&phi;}}+\frac{z_0-z_1}{z_1}{\stackrel{.}{I}}_0)\right|<\left|x_{\mathrm{set}}({\stackrel{.}{I}}_{\mathrm{\&phi;}}+\frac{z_0-z_1}{z_1}{\stackrel{.}{I}}_0)z_1\right|$ Whether set up, if set up, then protective device sends the would trip signal, the circuit breaker at tripping φ phase transmission line two ends; Wherein, φ=A phase, B phase, C phase.

The inventive method equates with residual voltage that according to the equivalent positive sequence voltage sudden change amount of transmission line one-phase earth fault point principle computing electric power line protection installation place is to the fault impedance of single phase ground fault point; computing electric power line protection installation place is to the voltage drop amplitude of single phase ground fault point; computing electric power line protection installation place is to the voltage drop amplitude at line protection setting range place; judge whether the line protection installation place sets up to the voltage drop amplitude at line protection setting range place less than the line protection installation place to the voltage drop amplitude of single phase ground fault point; if set up; judge that then the single phase ground fault point is positioned at the line protection setting range; send the would trip signal, the circuit breaker at tripping fault phase circuit two ends.The inventive method utilizes transmission line voltage distribution character along the line to realize the transmission line one-phase earth fault voltage protection; eliminated the influence of transition resistance to the protection performance on the principle; performance is not subjected to the influence of load current and abort situation, is applicable to the relaying protection in the two cycle times behind the transmission line one-phase earth fault.

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 guard method of the compound order component voltage of transmission line is characterized in that, comprises following sequential steps:

(1) the fault phase current of protector measuring line protection installation place , positive sequence voltage sudden change amount

, fault phase forward-order current sudden change amount , residual voltage

And zero-sequence current

Wherein, φ=A phase, B phase, C phase;

(2) protective device computing electric power line protection installation place is to the fault impedance Z of single phase ground fault point _φ:

$Z_{\mathrm{\&phi;}}=\frac{(z_1+z_0){\stackrel{.}{U}}_0+z_0\mathrm{\&Delta;}{\stackrel{.}{U}}_{\mathrm{\&phi;}1}}{(z_1+z_0)z_0{\stackrel{.}{I}}_0+z_1{z}_0\mathrm{\&Delta;}{\stackrel{.}{I}}_{\mathrm{\&phi;}1}}{z}_1$

Wherein, φ=A phase, B phase, C phase; z ₁Be unit length transmission line positive sequence impedance; z ₀Be unit length transmission line zero sequence impedance;

Be fault phase positive sequence voltage sudden change amount; Be fault phase forward-order current sudden change amount;

Be residual voltage;

Be zero-sequence current;

(3) protective device is judged $\left|Z_{\mathrm{\&phi;}}({\stackrel{.}{I}}_{\mathrm{\&phi;}}+\frac{z_0-z_1}{z_1}{\stackrel{.}{I}}_0)\right|<\left|x_{\mathrm{set}}({\stackrel{.}{I}}_{\mathrm{\&phi;}}+\frac{z_0-z_1}{z_1}{\stackrel{.}{I}}_0)z_1\right|$ Whether set up, if set up, then protective device sends the would trip signal, the circuit breaker at tripping φ phase transmission line two ends; Wherein, φ=A phase, B phase, C phase; x _SetBe the line protection setting range.