CN103869220A - Direct sampling and direct tripping communication mode-based double-circuit line single-phase earth fault positioning method - Google Patents

Abstract

The invention discloses a direct sampling and direct tripping communication mode-based double-circuit line single-phase earth fault positioning method, which comprises the steps: measuring the fault phase voltage, fault phase current and zero-sequence current of the circuit line I at the protection installation place of a common-tower double-circuit line, measuring the other two normal phase voltages, measuring the zero-sequence current of the circuit line II, and calculating the fault phase voltage when the circuit line I works normally by utilizing the two normal phase voltages of the circuit line I; starting from the protection installation place of the common-tower double-circuit line, sequentially calculating the phase angle that the fault phase voltage at each point of the circuit line I precedes the fault phase voltage when the circuit line I works normally in a fixed step length increment manner, and realizing the precise positioning of single-phase earth fault of the double-circuit line by virtue of the characteristic that the ratio of previous voltage to later voltage at the fault point has step change relative to the phase angle. According to the positioning method, the voltage before line fault does not need to be memorized, a voltage holding loop before the line fault does not need to be set; the influence of transition resistance, load current and interline zero-sequence mutual inductance on fault range accuracy is eliminated.

Description

Based on directly adopting straight jumping communication mode double-circuit line method for locating single-phase ground fault

Technical field

The present invention relates to Relay Protection Technology in Power System field, specifically relate to a kind of based on directly adopting straight jumping communication mode double-circuit line method for locating single-phase ground fault.

Background technology

Divide from the electric parameters used of finding range, the method for fault localization can be divided into two large classes: both-end distance measuring and single end distance measurement.Two-terminal Fault Location method is to utilize transmission line of electricity two ends electric parameters to determine the method for transmission line malfunction position, and it need to obtain opposite end electric parameters by passage, therefore strong to the dependence of passage, is also subject to the impact of both-end sampling value synchronization in actual use.Single end distance measurement method is only to utilize the electric current and voltage data of transmission line of electricity one end to determine a kind of method of transmission line malfunction position, because it only needs an end data, need not communication and data synchronizer, operating cost is low and algorithm stable, therefore in mid & low-voltage line, has obtained application widely.At present, method of single end distance measurement is mainly divided into two classes, and a class is traveling wave method, and another kind of is impedance method.Traveling wave method utilizes the transmission character of fault transient travelling wave to find range, and precision is high, not affected by the method for operation, excessive resistance etc., but very high to sampling rate requirement, needs special wave recording device, does not obtain at present substantial application.Impedance method is utilized the voltage after fault, the impedance that the magnitude of current calculates fault loop, the characteristic being directly proportional to impedance according to line length is found range, range measurement principle is simple and reliable, but while being applied to analyses for double circuits on same tower singlephase earth fault one-end fault ranging, distance accuracy is subject to zero-sequence mutual inductance between trouble spot transition resistance and line to be affected serious.Between analyses for double circuits on same tower line, have zero-sequence mutual inductance, zero-sequence mutual inductance can exert an influence to zero sequence compensation coefficient, and then causes impedance method range finding resultant error bigger than normal.If there is single-phase high resistance earthing fault in analyses for double circuits on same tower, be subject to zero-sequence mutual inductance and high transition resistance combined influence between line, impedance method range finding result usually exceeds total track length or without range finding result, abort situation information accurately cannot be provided, cause line fault line walking difficulty, be unfavorable for the fast quick-recovery of quick elimination of fault and line powering.

Summary of the invention

The object of the invention is to overcome the deficiency that prior art exists; non-fault range finding dead band when a kind of protection forward outlet single back line singlephase earth fault is provided; without voltage before line fault is remembered; keep loop without voltage before line fault is set, utilize before and after trouble spot voltage ratio phase phase angle that step evolution can occur and change this characteristic and realize the pinpoint method of double-circuit line singlephase earth fault.

The technical solution adopted for the present invention to solve the technical problems is: based on directly adopting straight jumping communication mode double-circuit line method for locating single-phase ground fault, comprise following sequential steps:

(1) the I loop line road fault phase voltage of protection installation place, protector measuring double-circuit line on same pole road

i loop line road fault phase electric current

with I loop line road zero-sequence current

measure other two normal phases voltages of I loop line road

with II loop line road zero-sequence current

wherein, φ α β is ACB phase or BAC phase or CBA phase;

(2) φ phase voltage when protective device calculating I loop line road is normally moved

wherein, φ α β is ACB phase or BAC phase or CBA phase;

(3) to choose fault distance initial value be l to protective device _x, calculating on I loop line road, double-circuit line on same pole road is l apart from protection installation place, double-circuit line on same pole road fault distance _xthe φ phase voltage of point

wherein, z _i1, z _i0be respectively unit length I loop line road positive sequence impedance, zero sequence impedance; z _m0for the zero-sequence mutual inductance impedance between unit length I loop line road and unit length II loop line road;

(4) fault distance initial value l _xwith fixed step size Δ, l increases progressively, and returns to step (3) and calculates successively the φ phase voltage of every bit on I loop line road, double-circuit line on same pole road

φ phase voltage when leading I loop line road is normally moved $-j\frac{{\stackrel{\·}{U}}_{\mathrm{I\α}}-{\stackrel{\·}{U}}_{\mathrm{I\β}}}{\sqrt{3}}$ Phase angle $\mathrm{\θ}\left(l_x\right)=\mathrm{Arg}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{I\φ}}-l_x{z}_{I1}({\stackrel{\·}{I}}_{\mathrm{I\φ}}+\frac{z_{I0}-z_{I1}}{z_{I1}}{\stackrel{\·}{I}}_{I0}+\frac{z_{m0}}{3z_{I1}}{\stackrel{\·}{I}}_{\mathrm{II}0})}{-j\frac{{\stackrel{\·}{U}}_{\mathrm{I\α}}-{\stackrel{\·}{U}}_{\mathrm{I\β}}}{\sqrt{3}}}\right),$ Until double-circuit line on same pole road I returns total track length;

(5) choose l on I loop line road, double-circuit line on same pole road _xθ (the l that point is corresponding _x) drop in (90 °, 270 °) and its adjacent next l _xθ (the l that+Δ l point is corresponding _x+ Δ l) drops in (90 °, 90 °), and this centre position of 2 is trouble spot.

The invention has the beneficial effects as follows:

Fault phase voltage when the inventive method is utilized same loop line road two normal phase voltages after fault to calculate in real time double-circuit line normally to move, without voltage before line fault is remembered, keeps loop without voltage before line fault is set.The inventive method utilizes voltage ratio phase phase angle before and after trouble spot that the accurate location that step evolution changes this characteristic and realizes double-circuit line singlephase earth fault can occur; in principle, eliminate the impact on fault localization precision of transition resistance and load current, non-fault range finding dead band in the time of protection forward outlet single back line singlephase earth fault.The inventive method utilization is directly adopted straight jumping communication mode and is obtained another loop line road zero-sequence current, takes into account the impact of another loop line road zero-sequence current in algorithm model, has eliminated the impact of zero-sequence mutual inductance on fault localization precision between line in principle, has very high distance accuracy.

Accompanying drawing explanation

Fig. 1 is application double-circuit line on same pole of the present invention road transmission system schematic diagram.

Embodiment

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

Fig. 1 is application double-circuit line on same pole of the present invention road transmission system schematic diagram.In Fig. 1, CVT is that voltage transformer (VT), CT are current transformer.In intelligent substation; sampled digital signal transmission channel is carried out to SV network communication networking; after the ac analog of merge cells Real-time Collection voltage transformer (VT) CVT summation current transformer CT output; the ac analog of the voltage transformer (VT) CVT summation current transformer CT output collecting is changed into sampled digital signal by merge cells; be transferred to interchanger through optical-fibre communications, and then be directly transferred to protective relaying device through optical-fibre communications.

One of the present invention, based on directly adopting straight jumping communication mode double-circuit line method for locating single-phase ground fault, comprises following sequential steps:

Protective relaying device is measured the I loop line road fault phase voltage of protection installation place, double-circuit line on same pole road

i loop line road fault phase electric current with I loop line road zero-sequence current

measure other two normal phases voltages of I loop line road

with II loop line road zero-sequence current

wherein, φ α β is ACB phase or BAC phase or CBA phase, that is, when φ=A phase time, α=C phase, β=B phase; When φ=B phase time, α=A phase, β=C phase; When φ=C phase time, α=B phase, β=A phase; Above-mentioned I loop line road refers to a loop line road of fault in double-circuit line on same pole road, II loop line road refer in double-circuit line on same pole road normal operation another loop line road;

φ phase voltage when protective relaying device calculating I loop line road is normally moved wherein, φ α β is ACB phase or BAC phase or CBA phase, that is, when φ=A phase time, α=C phase, β=B phase; When φ=B phase time, α=A phase, β=C phase; When φ=C phase time, α=B phase, β=A phase;

It is l that protective relaying device is chosen fault distance initial value _x, calculating on I loop line road, double-circuit line on same pole road is l apart from protection installation place, double-circuit line on same pole road fault distance _xthe φ phase voltage of point wherein, z _i1, z _i0be respectively unit length I loop line road positive sequence impedance, zero sequence impedance; z _m0for the zero-sequence mutual inductance impedance between unit length I loop line road and unit length II loop line road;

Fault distance initial value l _xwith fixed step size Δ, l increases progressively, and calculates successively the φ phase voltage of every bit on I loop line road, double-circuit line on same pole road

φ phase voltage when leading I loop line road is normally moved

phase angle $\mathrm{\θ}\left(l_x\right)=\mathrm{Arg}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{I\φ}}-l_x{z}_{I1}({\stackrel{\·}{I}}_{\mathrm{I\φ}}+\frac{z_{I0}-z_{I1}}{z_{I1}}{\stackrel{\·}{I}}_{I0}+\frac{z_{m0}}{3z_{I1}}{\stackrel{\·}{I}}_{\mathrm{II}0})}{-j\frac{{\stackrel{\·}{U}}_{\mathrm{I\α}}-{\stackrel{\·}{U}}_{\mathrm{I\β}}}{\sqrt{3}}}\right),$ Until double-circuit line on same pole road I returns total track length;

Choose l on I loop line road, double-circuit line on same pole road _xθ (the l that point is corresponding _x) drop in (90 °, 270 °) and its adjacent next l _xθ (the l that+Δ l point is corresponding _x+ Δ l) drops in (90 °, 90 °), and this centre position of 2 is trouble spot.

Fault phase voltage when the inventive method is utilized same loop line road two normal phase voltages after fault to calculate in real time double-circuit line normally to move, without voltage before line fault is remembered, keeps loop without voltage before line fault is set.

The inventive method utilizes voltage ratio phase phase angle before and after trouble spot that the accurate location that step evolution changes this characteristic and realizes double-circuit line singlephase earth fault can occur; in principle, eliminate the impact on fault localization precision of transition resistance and load current, non-fault range finding dead band in the time of protection forward outlet single back line singlephase earth fault.

The inventive method utilization is directly adopted straight jumping communication mode and is obtained another loop line road zero-sequence current, takes into account the impact of another loop line road zero-sequence current in algorithm model, has eliminated the impact of zero-sequence mutual inductance on fault localization precision between line in principle, has very high distance accuracy.

The foregoing is only preferred embodiment of the present invention; but protection scope of the present invention is not limited to this; any be familiar with those skilled in the art the present invention disclose technical scope in, the variation that can expect easily or replacement, within all should being encompassed in protection scope of the present invention.

Claims (1)

1. based on directly adopting straight jumping communication mode double-circuit line method for locating single-phase ground fault, it is characterized in that, comprise following sequential steps:

(1) the I loop line road fault phase voltage of protection installation place, protector measuring double-circuit line on same pole road

i loop line road fault phase electric current with I loop line road zero-sequence current

measure other two normal phases voltages of I loop line road

with II loop line road zero-sequence current

wherein, φ α β is ACB phase or BAC phase or CBA phase;

(2) φ phase voltage when protective device calculating I loop line road is normally moved wherein, φ α β is ACB phase or BAC phase or CBA phase;

(3) to choose fault distance initial value be l to protective device _x, calculating on I loop line road, double-circuit line on same pole road is l apart from protection installation place, double-circuit line on same pole road fault distance _xthe φ phase voltage of point

wherein, z _i1, z _i0be respectively unit length I loop line road positive sequence impedance, zero sequence impedance; z _m0for the zero-sequence mutual inductance impedance between unit length I loop line road and unit length II loop line road;

(4) fault distance initial value l _xwith fixed step size Δ, l increases progressively, and returns to step (3), calculates successively the φ phase voltage of every bit on I loop line road, double-circuit line on same pole road

φ phase voltage when leading I loop line road is normally moved $-j\frac{{\stackrel{\·}{U}}_{\mathrm{I\α}}-{\stackrel{\·}{U}}_{\mathrm{I\β}}}{\sqrt{3}}$ Phase angle $\mathrm{\θ}\left(l_x\right)=\mathrm{Arg}\left(\frac{{\stackrel{\·}{U}}_{\mathrm{I\φ}}-l_x{z}_{I1}({\stackrel{\·}{I}}_{\mathrm{I\φ}}+\frac{z_{I0}-z_{I1}}{z_{I1}}{\stackrel{\·}{I}}_{I0}+\frac{z_{m0}}{3z_{I1}}{\stackrel{\·}{I}}_{\mathrm{II}0})}{-j\frac{{\stackrel{\·}{U}}_{\mathrm{I\α}}-{\stackrel{\·}{U}}_{\mathrm{I\β}}}{\sqrt{3}}}\right),$ Until double-circuit line on same pole road I returns total track length;

(5) choose l on I loop line road, double-circuit line on same pole road _xθ (the l that point is corresponding _x) drop in (90 °, 270 °) and its adjacent next l _xθ (the l that+Δ l point is corresponding _x+ Δ l) drops in (90 °, 90 °), and this centre position of 2 is trouble spot.

Images