CN104330705A - Line interphase fault single-ended distance measurement method based on interphase fault location factor - Google Patents

Abstract

The invention discloses a line interphase fault single-ended distance measurement method based on an interphase fault location factor. The method includes firstly, calculating the ratio of fault impedance, from an electric transmission line protection mounting position to an interphase short-circuit fault point, to line impedance, from the electric transmission line protection mounting position to an electric transmission line protection setting range, to acquire the electric transmission line interphase fault location factor b; selecting a fault location default value as lfault, and sequentially calculating the absolute values of [Zc1th(gamma1lfault)/Zc1th(gamma1lset)]-b of points on an electric transmission line by means of progressive increase of a fixed step length delta l until the total length of the electric transmission line is calculated; selecting the distance between the point with the maximum absolute value of [Zc1th(gamma1lfault)/Zc1th(gamma1lset)]-b on the electric transmission line and the electric transmission line protection mounting position as the fault distance. The method has the advantages that influences of electric transmission line interphase short-circuit fault point voltage, transition resistance and load current on electric transmission line interphase short-circuit fault single-ended distance measurement accuracy are eliminated theoretically, and the method has high distance measurement accuracy and is particularly applicable to interphase short-circuit fault single-ended distance measurement of extra-high-voltage alternating-current electric transmission lines.

Description

Based on the circuit inter-phase fault single-end ranging of phase-to phase fault location factor

Technical field

The present invention relates to Relay Protection Technology in Power System field, specifically relate to a kind of circuit inter-phase fault single-end ranging based on phase-to phase fault location factor.

Background technology

Divide according to electric parameters source, fault distance-finding method is mainly divided into both-end distance measuring method and method of single end distance measurement.Both-end distance measuring method utilizes transmission line of electricity two ends electric parameters to carry out localization of fault, needs to obtain opposite end electric parameters by data transmission channel, strong to data transmission channel-independent, is also subject to the impact of both-end sampling value synchronization in actual use.Ultrahigh voltage alternating current transmission lines is long-distance transmission line often, and the data transmission channel laid needed for range finding needs additional investment substantial contribution, and therefore, method of single end distance measurement has more practicality than both-end distance measuring method.Method of single end distance measurement only utilizes transmission line of electricity one end electric parameters to carry out localization of fault, need not communication and data syn-chronization equipment, and the low and algorithmic stability of operating cost, obtains widespread use in high, normal, basic pressure transmission line.

At present, method of single end distance measurement is mainly divided into traveling wave method and impedance method.Traveling wave method utilizes the transmission character of fault transient travelling wave to carry out one-end fault ranging, and precision is high, does not affect by the method for operation, excessive resistance etc., but requires very high to sampling rate, and need special wave recording device, application cost is high.Impedance method utilizes the voltage after fault, the magnitude of current to calculate Fault loop impedance, one-end fault ranging is carried out according to the characteristic that line length is directly proportional to impedance, simple and reliable, but it is serious that distance accuracy is subject to the impact of the factor such as transition resistance and load current, especially when transition resistance is larger, finding range unsuccessfully, even appear in impedance method range measurement meeting substantial deviation true fault distance.Because UHV transmission line exists larger capacitance current along the line, when during UHV transmission line occurs during high resistant short trouble, single-ended impedance method range measurement can substantial deviation true fault distance, can not meet on-the-spot application requirement.Therefore, the single-ended impedance method of lumped parameter modeling is adopted can not to directly apply to the one-end fault ranging of UHV transmission line.

Summary of the invention

The object of the invention is to the deficiency overcoming prior art existence, a kind of circuit inter-phase fault single-end ranging based on phase-to phase fault location factor is provided.The inventive method first computing electric power line protection installation place, to the fault impedance of phase fault point and line protection installation place to the ratio of the line impedance at line protection setting range place, obtains electric transmission line phase fault location factor b; Then choosing fault distance initial value is l _fault, increase progressively every bit on computing electric power line successively with fixed step size Δ l value, until transmission line of electricity total length; Choose on transmission line of electricity and meet minimum point is fault distance apart from the distance of line protection installation place.The inventive method adopts long-line equation accurately to describe the physical characteristics of transmission line of electricity, has the ability of natural anti-distributed capacitance impact.The inventive method principle eliminates the impact on electric transmission line phase fault single end distance measurement precision of voltage at interphase short circuit fault point of power transmission line, transition resistance and load current, there is very high distance accuracy, be specially adapted to ultrahigh voltage alternating current transmission lines phase fault single end distance measurement.

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

Based on the circuit inter-phase fault single-end ranging of phase-to phase fault location factor, it is characterized in that, comprise following sequential steps:

(1) the fault voltage between phases of protector measuring line protection installation place fault three-phase current and negative-sequence current between fault phase wherein, φ φ=AB, BC, CA phase;

(2) protective device calculates γ ₁l _sethyperbolic cosine function value ch (γ ₁l _set), calculate γ ₁l _sethyperbolic tangent function value th (γ ₁l _set); Wherein, l _setfor line protection setting range, get 0.85 times of transmission line length; γ ₁for electric transmission line positive sequence propagation coefficient;

(3) computing electric power line phase-to phase fault location factor b:

$b=\frac{\mathrm{Re}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(\frac{{\stackrel{.}{I}}_{\mathrm{\φ\φ}2}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right)-\mathrm{Im}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(\frac{{\stackrel{.}{I}}_{\mathrm{\φ\φ}2}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right)}{\mathrm{Re}\left(Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right){\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(\frac{{\stackrel{.}{I}}_{\mathrm{\φ\φ}2}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right)-\mathrm{Im}\left(Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right){\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(\frac{{\stackrel{.}{I}}_{\mathrm{\φ\φ}2}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right)}$

Wherein, φ φ=AB, BC, CA phase; l _setfor line protection setting range, get 0.85 times of transmission line length; γ ₁for electric transmission line positive sequence propagation coefficient; Z _c1for electric transmission line positive sequence wave impedance; for real part; for imaginary part; for real part; for imaginary part; for real part; for imaginary part;

(4) fault distance initial value chosen by protective device is l _fault, to increase progressively with fixed step size Δ l, successively every bit place on computing electric power line value, until transmission line of electricity total length; Wherein, fixed step size Δ l gets 0.001l; L is transmission line length; l _setfor line protection setting range, get 0.85 times of transmission line length; γ ₁for electric transmission line positive sequence propagation coefficient; Z _c1for electric transmission line positive sequence wave impedance; Fault distance initial value l _faultget 0 beginning, increase progressively until transmission line of electricity total length l terminates with fixed step size Δ l;

(5) protective device is chosen on transmission line of electricity and is met minimum point is fault distance apart from the distance of line protection installation place; Wherein, th (γ ₁l _fault) be γ ₁l _faulthyperbolic tangent function value.

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

The inventive method first computing electric power line protection installation place, to the fault impedance of phase fault point and line protection installation place to the ratio of the line impedance at line protection setting range place, obtains electric transmission line phase fault location factor b; Then choosing fault distance initial value is l _fault, increase progressively every bit on computing electric power line successively with fixed step size Δ l value, until transmission line of electricity total length; Choose on transmission line of electricity and meet minimum point is fault distance apart from the distance of line protection installation place.The inventive method adopts long-line equation accurately to describe the physical characteristics of transmission line of electricity, has the ability of natural anti-distributed capacitance impact.The inventive method principle eliminates the impact on electric transmission line phase fault single end distance measurement precision of voltage at interphase short circuit fault point of power transmission line, transition resistance and load current, there is very high distance accuracy, be specially adapted to ultrahigh voltage alternating current transmission lines phase fault single end distance measurement.

Accompanying drawing explanation

Fig. 1 is application multi-line power transmission system schematic of the present invention.

Embodiment

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

Fig. 1 is application multi-line power transmission system schematic of the present invention.In Fig. 1, CVT is voltage transformer (VT), CT is current transformer.The current waveform of protective device to the potential and current transformers CT of the voltage transformer (VT) CVT of line protection installation place carries out sampling and obtains voltage, current instantaneous value.

The voltage that protective device obtains sampling, current instantaneous value utilize Fourier algorithm computing electric power line to protect the fault voltage between phases of installation place fault three-phase current and negative-sequence current between fault phase wherein, φ φ=AB, BC, CA phase.

Protective device calculates γ ₁l _sethyperbolic cosine function value ch (γ ₁l _set).

Protective device calculates γ ₁l _sethyperbolic tangent function value th (γ ₁l _set).

Wherein, l _setfor line protection setting range, get 0.85 times of transmission line length; γ ₁for electric transmission line positive sequence propagation coefficient.

Protective device computing electric power line phase-to phase fault location factor b:

$b=\frac{\mathrm{Re}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(\frac{{\stackrel{.}{I}}_{\mathrm{\φ\φ}2}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right)-\mathrm{Im}\left({\stackrel{.}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(\frac{{\stackrel{.}{I}}_{\mathrm{\φ\φ}2}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right)}{\mathrm{Re}\left(Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right){\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(\frac{{\stackrel{.}{I}}_{\mathrm{\φ\φ}2}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right)-\mathrm{Im}\left(Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right){\stackrel{.}{I}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(\frac{{\stackrel{.}{I}}_{\mathrm{\φ\φ}2}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right)}$

Wherein, φ φ=AB, BC, CA phase; l _setfor line protection setting range, get 0.85 times of transmission line length; γ ₁for electric transmission line positive sequence propagation coefficient; Z _c1for electric transmission line positive sequence wave impedance; for real part; for imaginary part; for real part; for imaginary part; for real part; for imaginary part.

Fault distance initial value chosen by protective device is l _fault, to increase progressively with fixed step size Δ l, successively every bit place on computing electric power line value, until transmission line of electricity total length; Wherein, fixed step size Δ l gets 0.001l; L is transmission line length; l _setfor line protection setting range, get 0.85 times of transmission line length; γ ₁for electric transmission line positive sequence propagation coefficient; Z _c1for electric transmission line positive sequence wave impedance; Fault distance initial value l _faultget 0 beginning, increase progressively until transmission line of electricity total length l terminates with fixed step size Δ l; Th (γ ₁l _fault) be γ ₁l _faulthyperbolic tangent function value.

Protective device is chosen on transmission line of electricity and is met minimum point is fault distance apart from the distance of line protection installation place.

The inventive method first computing electric power line protection installation place, to the fault impedance of phase fault point and line protection installation place to the ratio of the line impedance at line protection setting range place, obtains electric transmission line phase fault location factor b; Then choosing fault distance initial value is l _fault, increase progressively every bit on computing electric power line successively with fixed step size Δ l value, until transmission line of electricity total length; Choose on transmission line of electricity and meet minimum point is fault distance apart from the distance of line protection installation place.The inventive method adopts long-line equation accurately to describe the physical characteristics of transmission line of electricity, has the ability of natural anti-distributed capacitance impact.The inventive method principle eliminates the impact on electric transmission line phase fault single end distance measurement precision of voltage at interphase short circuit fault point of power transmission line, transition resistance and load current, there is very high distance accuracy, be specially adapted to ultrahigh voltage alternating current transmission lines phase fault single end distance measurement.

The foregoing is only 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 change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.

Claims (1)

1. based on the circuit inter-phase fault single-end ranging of phase-to phase fault location factor, it is characterized in that, comprise following sequential steps:

(1) the fault voltage between phases of protector measuring line protection installation place fault three-phase current and negative-sequence current between fault phase wherein, φ φ=AB, BC, CA phase.

(2) protective device calculates γ ₁l _sethyperbolic cosine function value ch (γ ₁l _set), calculate γ ₁l _sethyperbolic tangent function value th (γ ₁l _set); Wherein, l _setfor line protection setting range, get 0.85 times of transmission line length; γ ₁for electric transmission line positive sequence propagation coefficient;

(3) protective device computing electric power line phase-to phase fault location factor b:

$b=\frac{\mathrm{Re}\left({\stackrel{\·}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(\frac{{\stackrel{\·}{I}}_{\mathrm{\φ\φ}2}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right)-\mathrm{Im}\left({\stackrel{\·}{U}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(\frac{{\stackrel{\·}{I}}_{\mathrm{\φ\φ}2}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right)}{\mathrm{Re}\left(Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right){\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)\mathrm{Im}\left(\frac{{\stackrel{\·}{I}}_{\mathrm{\φ\φ}2}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right)-\mathrm{Im}\left(Z_{c1}\mathrm{th}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right){\stackrel{\·}{I}}_{\mathrm{\φ\φ}}\right)\mathrm{Re}\left(\frac{{\stackrel{\·}{I}}_{\mathrm{\φ\φ}2}}{\mathrm{ch}\left({\mathrm{\γ}}_1{l}_{\mathrm{set}}\right)}\right)}$

Wherein, φ φ=AB, BC, CA phase; l _setfor line protection setting range, get 0.85 times of transmission line length; γ ₁for electric transmission line positive sequence propagation coefficient; Z _c1for electric transmission line positive sequence wave impedance; real part; for imaginary part; for real part; for imaginary part; for real part; for imaginary part;

(4) fault distance initial value chosen by protective device is l _fault, to increase progressively with fixed step size Δ l, successively every bit place on computing electric power line value, until transmission line of electricity total length; Wherein, fixed step size Δ l gets 0.001l; L is transmission line length; l _setfor line protection setting range, get 0.85 times of transmission line length; γ ₁for electric transmission line positive sequence propagation coefficient; Z _c1for electric transmission line positive sequence wave impedance; Fault distance initial value l _faultget 0 beginning, increase progressively until transmission line of electricity total length l terminates with fixed step size Δ l;

(5) protective device is chosen on transmission line of electricity and is met minimum point is fault distance apart from the distance of line protection installation place; Wherein, th (γ ₁l _fault) be γ ₁l _faulthyperbolic tangent function value.