CN103199508A - Method for achieving electric transmission line single phase grounding fault relay protection by using distribution parameter - Google Patents

Abstract

The invention discloses a method for achieving electric transmission line single phase grounding fault relay protection by using a distribution parameter. According to the method, the physical characteristic that a long line equation precisely describes transmission of voltages and currents of an electric transmission line is used, the fault phase electrical quantity at a protection mounting position is used for calculating the fault impedance amplitude of the electric transmission line from the protection mounting position of the electric transmission line to a single phase grounding fault point, the size relationship between the fault impedance amplitude of the electric transmission line and the protection setting impedance amplitude of the electric transmission line is compared, if the fault impedance amplitude of the electric transmission line is smaller than the protection setting impedance amplitude of the electric transmission line, an action tripping signal is protected to send. The method is used for extra-high voltage alternating current electric transmission line single phase grounding fault relay protection, and is capable of calculating the fault impedance amplitude precisely, the action performance is not influenced by grounding fault point voltages, distribution capacitance currents, transition resistors and load currents, and the action performance can meet the demands for relay protection selectivity, reliability, sensitivity and quick-action performance.

Description

Utilize distributed constant to realize the transmission line one-phase earth fault relay protecting method

Technical field

The present invention relates to the relay protection of power system technical field, specifically relate to a kind of distributed parameter model that utilizes and realize the transmission line one-phase earth fault relay protecting method.

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, has obtained 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 fault impedance size 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 the electric parameters that is used for the calculating fault 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.

Yet traditional impedance ground distance protection prerequisite hypothesis earth fault point voltage is zero, by fault phase voltage and fault phase current ratio calculation fault impedance, and reflects according to the fault impedance size whether the distance of fault point sends trip signal with decision.In fact, in electric power system, except the metallic earthing short trouble of arteface, the earth fault point voltage may be zero hardly, and therefore, the earth fault point voltage can cause impedance ground distance protection performance and have a strong impact on.

In the practical power systems, the voltage of ultrahigh voltage alternating current transmission lines, current delivery have tangible wave process, and capacitance current along the line is big, can not ignore the influence of impedance distance protection performance.Consider the influence of circuit direct-to-ground capacitance along the line, fault impedance and fault distance are the hyperbolic tangent function relation, the hyperbolic tangent function characteristic has determined the anti-transition resistance ability of impedance relay, and the additional impedance that transition resistance brings will have a strong impact on the performance of impedance relay.Big capacity electric energy is carried in the extreme pressure transmission line of alternation current, is the heavy load transmission line, and the heavy load electric current can make the action sensitivity of impedance distance protection reduce, and the heavy load electric current can not be ignored the influence of impedance distance protection performance.

Add up according to State Grid Corporation of China; single phase ground fault accounts for more than 80% in the various fault types that power system transmission line takes place; therefore, a kind of relay protecting method of ultrahigh voltage alternating current transmission lines single phase ground fault that is applicable to of research has very important engineering significance.

Summary of the invention

The objective of the invention is to overcome the deficiency that prior art exists, provide a kind of distributed parameter model that utilizes of ultrahigh voltage alternating current transmission lines that is applicable to realize the relay protecting method of transmission line one-phase earth fault.

The objective of the invention is to realize by following approach:

Utilize distributed parameter model to realize the transmission line one-phase earth fault relay protecting method, its main points are, comprise the steps:

(1) provides a kind of protective device, the fault phase voltage of this protector measuring line protection installation place

The fault phase current

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

(2) protective device utilizes its fault phase electric parameters that measures to calculate the fault impedance amplitude of φ phase transmission line | Z _φ|:

$\left|Z_{\mathrm{\φ}}\right|=\left|\frac{{\stackrel{\·}{U}}_{\mathrm{\φ}}}{{\stackrel{\·}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{\·}{I}}_0}\frac{\sin \mathrm{\β}}{\sin (\mathrm{\α}+\mathrm{\γ})}\right|$

Wherein, φ=A, B, C phase; l _SetBe the protection setting range; Z ₀System's zero sequence equivalent impedance for the line protection installation place; γ ₁, γ ₀Be respectively transmission line positive sequence, zero sequence propagation coefficient; Z _C1, Z _C0Be respectively transmission line positive sequence, zero sequence wave impedance; $\mathrm{\γ}=\mathrm{Arg}\left(\frac{{\stackrel{\·}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{\·}{I}}_0}{{\stackrel{\·}{I}}_{\mathrm{\φ}2}}\right);$ $\mathrm{\β}=\mathrm{Arg}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{\φ}}}{{\stackrel{\·}{I}}_{\mathrm{\φ}2}}\right);$ Ch (.) is hyperbolic cosine function; α=Arg (Z _C1Th (γ ₁l _Set)); Sh (.) is hyperbolic sine function.

(3) the protective device protection of further the calculating φ phase transmission line impedance magnitude of adjusting | Z _C1Th (γ ₁l _Set) |, wherein, th (.) is hyperbolic tangent function;

(4) protective device is relatively | Z _C1Th (γ ₁l _Set) | with | Z _φ| between magnitude relationship, if satisfy | Z _φ|＜| Z _C1Th (γ ₁l _Set) |, then the would trip signal is sent in protection.

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

(1) the inventive method adopts long-line equation accurately to describe the physical characteristic of transmission line, has the ability of natural anti-distributed capacitance influence.

(2) the inventive method energy accurate Calculation transmission line malfunction impedance magnitude; as the relaying protection of ultrahigh voltage alternating current transmission lines single phase ground fault; its performance is not subjected to the influence of earth fault point voltage, capacitance current, transition resistance and load current, and performance is reliable and stable.

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.CVT is that voltage transformer, CT are current transformer among Fig. 1.Protective device is sampled to the current waveform of the voltage waveform summation current transformer CT of the voltage transformer CVT of line protection installation place and is obtained voltage, current instantaneous value.

The voltage that protective device obtains sampling, current instantaneous value utilize the fault phase voltage of Fourier algorithm computing electric power line protection installation place

The fault phase current

Fault phase negative-sequence current

And zero-sequence current

Wherein, φ=A, B, C phase.

Protective device utilizes its fault phase electric parameters that measures to calculate the fault impedance amplitude of φ phase transmission line | Z _φ|:

$\left|Z_{\mathrm{\φ}}\right|=\left|\frac{{\stackrel{\·}{U}}_{\mathrm{\φ}}}{{\stackrel{\·}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{\·}{I}}_0}\frac{\sin \mathrm{\β}}{\sin (\mathrm{\α}+\mathrm{\γ})}\right|$

Wherein, φ=A, B, C phase; l _SetBe the protection setting range; Z ₀System's zero sequence equivalent impedance for the line protection installation place; γ ₁, γ ₀Be respectively transmission line positive sequence, zero sequence propagation coefficient; Z _C1, Z _C0Be respectively transmission line positive sequence, zero sequence wave impedance; $\mathrm{\γ}=\mathrm{Arg}\left(\frac{{\stackrel{\·}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{\·}{I}}_0}{{\stackrel{\·}{I}}_{\mathrm{\φ}2}}\right);$ $\mathrm{\β}=\mathrm{Arg}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{\φ}}}{{\stackrel{\·}{I}}_{\mathrm{\φ}2}}\right);$ Ch (.) is hyperbolic cosine function; α=Arg (Z _C1Th (γ ₁l _Set)); Sh (.) is hyperbolic sine function.

The protection that protective device further the calculates φ phase transmission line impedance magnitude of adjusting | Z _C1Th (γ ₁l _Set) |, wherein, th (.) is hyperbolic tangent function.

Protective device compares | Z _C1Th (γ ₁l _Set) | with | Z _φ| between magnitude relationship, if satisfy | Z _φ|＜| Z _C1Th (γ ₁l _Set) |, then the would trip signal is sent in protection.

Use the inventive method as the relaying protection of ultrahigh voltage alternating current transmission lines single phase ground fault; energy accurate Calculation fault impedance amplitude; its performance is not subjected to the influence of earth fault point voltage, capacitance current, transition resistance and load current, and its performance satisfies the requirement of selectivity of relay protection, reliability, sensitivity and quick-action.

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 distributed constant to realize the transmission line one-phase earth fault relay protecting method, comprise the following steps:

(1) provides a kind of protective device, the fault phase voltage of this protector measuring line protection installation place

The fault phase current

Fault phase negative-sequence current

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

(2) protective device utilizes its fault phase electric parameters that measures to calculate the fault impedance amplitude of φ phase transmission line | Z _φ|:

$\left|Z_{\mathrm{\φ}}\right|=\left|\frac{{\stackrel{\·}{U}}_{\mathrm{\φ}}}{{\stackrel{\·}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{\·}{I}}_0}\frac{\sin \mathrm{\β}}{\sin (\mathrm{\α}+\mathrm{\γ})}\right|$

Wherein, φ=A, B, C phase; l _SetBe the protection setting range; Z ₀System's zero sequence equivalent impedance for the line protection installation place; γ ₁, γ ₀Be respectively transmission line positive sequence, zero sequence propagation coefficient; Z _C1, Z _C0Be respectively transmission line positive sequence, zero sequence wave impedance; $\mathrm{\γ}=\mathrm{Arg}\left(\frac{{\stackrel{\·}{I}}_{\mathrm{\φ}}+(\frac{Z_0\mathrm{ch}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)+Z_{c0}\mathrm{sh}\left({\mathrm{\γ}}_0{l}_{\mathrm{set}}\right)-Z_0\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}{Z_{c1}\mathrm{sh}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}-1){\stackrel{\·}{I}}_0}{{\stackrel{\·}{I}}_{\mathrm{\φ}2}}\right);$ $\mathrm{\β}=\mathrm{Arg}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{\φ}}}{{\stackrel{\·}{I}}_{\mathrm{\φ}2}}\right);$ Ch (.) is hyperbolic cosine function; α=Arg (Z _C1Th (γ ₁l _Set)); Sh (.) is hyperbolic sine function.

(3) the protective device protection of further the calculating φ phase transmission line impedance magnitude of adjusting | Z _C1Th (γ ₁l _Set) |, wherein, th (.) is hyperbolic tangent function;

(4) protective device is relatively | Z _C1Th (γ ₁l _Set) | with | Z _φ| between magnitude relationship, if satisfy | Z _φ|＜| Z _C1Th (γ ₁l _Set) |, then the would trip signal is sent in protection.

Images