CN1103451C - High-voltage overhead line on-line failure distance finding method and instrument installation - Google Patents

Abstract

The present invention relates to a method and an instrument for on-line detection of the distance of fault points of a high-voltage overhead electric transmission line. The present invention is characterized in that the reactance value of the high-voltage overhead electric transmission line is measured by hardware design and software design, and signal sampling, signal processing, numerical calculation and alarm display are completed under the control of a single chip computer. The instrument of the present invention comprises a transmitter, an analog-digital converting circuit, a digital optical isolating forced driver, a self regulating zero circuit and a grounding phase reversal switching circuit installed in a transformer station. The method and the instrument of the present invention have very important practical significance and wide application prospects to distance measurement of faults of high-voltage overhead electric transmission lines with single-ended power supplies of 10 to 35KV widely used in China.

Description

High-voltage overhead line on-line failure distance finding method and apparatus

The invention belongs to electric fault Detection Techniques field, relate to the method and the apparatus of a kind of online detection high pressure overhead power line trouble spot distance.

In electricity overhead power transmission line, because line fault is many, search difficulty, troubleshoot is a great problem that the electric industry operations staff faces always.For addressing this problem corresponding some fault distance-finding methods and the device of having occurred.In the prior art before the present invention, the normal method that adopts has:

What failure wave-recording method, pulse reflection method and electronic circuit constituted is target Detection with the measuring circuit impedance.The advantage of failure wave-recording method is that method is simple, but measuring accuracy is not high, and needs can locate through artificial calculating; Pulse reflection method is a kind of off-line distance-finding method, and its advantage is that low resistive fault and broken string are had effect preferably, but complex structure, debug difficulties especially is difficult for obtaining tangible feedback signal and can't makes judgement resistive fault of height and flashover fault; The impedance method range finding that electronic circuit constitutes, its circuit debugging difficulty is subject to disturb, and precision is not high.Above-mentioned these methods all can only be applied in limited scope.

Reactance method is that a kind of false voltage and electric current of utilizing calculates the fault loop reactance value.Thereby calibrate the method for fault distance, this method is not subjected to the influence of transition resistance, can reflect fault and fault distance truly, is applicable to the fault test of single ended power supply high-tension overhead line, thereby the report of reactance method fault localization appearred in recent years, as USSR (Union of Soviet Socialist Republics) SU1543354, ^*SU1590968, SU1661685 etc. patented claim.But the height that can only utilize the fault phase voltage that has in these patents carries out earth fault line selection, the estimation fault distance, ground loop reactance and accurate function of demarcating fault distance are measured in not possessing of having, what have can only detect the two-way outlet, and error is big, poor practicability, especially for the on-line measurement of the singlephase earth fault of isolated neutral system, better technical solution is not proposed still.

At above-mentioned prior art situation.The objective of the invention is to, based on the measuring circuit reactance value, provide a kind of both can online accurate detection and judge all kinds of line faults, again can accurate Calculation and show the method and the apparatus of all kinds of fault distances, especially can solve detection and range observation problem that additive method is difficult for the isolated neutral system singlephase earth fault that detects effectively.The accuracy of on-line measurement electrical network parameter, reliability and antijamming capability when simultaneously, the present invention also aims to improve fault.

Now design of the present invention and technical solution are described below:

For uniform transmission line, himself parameter resistance, reactance are directly proportional with line length, and when being short-circuited fault, the resistance of its short-circuit loop, the size of reactance value have just reflected the length of fault loop, thereby have also just reflected the distance of trouble spot; But for various short troubles, having many is non-metallic short circuits, can transition resistance occur and cause dysmetria in the trouble spot; Yet the reactance value of measuring the loop comes localization of faults distance just can not be affected; In addition, because the singlephase earth fault ratio is very big, and the 10-35KV network of widespread use is an isolated neutral system in the electric system, and conventional method can't be found range, even faulty line also can't be determined; Therefore, basic ideas of the present invention are: by the design to software and hardware, make all kinds of short circuits and earth fault all can be measured accurately, as: in the method design, adopt the fast fourier transform method of good wave filtering effect, detect the little instantaneous reactive power calculation of parameter method of time lag and the rotation vector method of recoverable mutual inductor angular difference; On the hardware circuit design of instrument, adopt the redundancy of alternative addition of constraints that each circuit can be changed mutually to the crux circuit part, do not disturb mutually, adopt the photoelectricity quarantine measures, improve the antijamming capability of instrument, on the corollary apparatus of instrument, designed unique ground connection phase reversal switch circuit, or the like, the difficult problem of searching and find range of fault solved well; Below, underdraw earlier and carry out the principle of short trouble range finding with reactance method:

Because the reactance value in the faulty circuit is not subjected to the influence of transition resistance, principle then can be directly proportional with length according to the line reactance value of transmission line, when circuit is short-circuited fault,, get final product the distance of the localization of faults by measuring the line reactance that calculates electric substation's (circuit head end) to trouble spot:

If head end voltage is U during short circuit _DShort-circuit current is I _D(as shown in Figure 1), then:

U _D=I _D(R+R _g)+jI _DX (1) can be got by (1):

In the formula:

, be U _DAnd I _DPhase differential; X---measured reactance value during short circuit.Then distance L is: $L=\frac{X}{x_1}---\left(3\right)$ X in the formula ₁Be the reactance value of circuit unit length, can be by finding in the electric power handbook.

Out of order type can be judged by measured voltage, current value,, the distance of fault can be accurately calculated by the reactance value that converses.Measurement for all kinds of faults such as single-phase earthing of three-phase shortcircuit, line to line fault, single-phase short circuit and isolated neutral system; Its principle is the same, the difference instrument be required measurement parameter by voltage between phases and the electric current in the formation loop.

According to above-mentioned principle, the method feature and the step of on-line measurement high-tension overhead line fault distance of the present invention following (referring to Fig. 2, Fig. 3):

1, transmitter after the standard signal conversion, send analog to digital conversion circuit with three-phase voltage, the current signal introduced.

When 2, sampling, by Single-chip Controlling, with the maintenance of sampling simultaneously of each road voltage and current signal, again by the Single-chip Controlling multi-way switch with signal after impedance matching, send the analog to digital conversion circuit conversion, the digital signal after the conversion is sent to the single-chip microcomputer subsystem through photoelectricity quarantine enforcement driving circuit; Carrying out normal effective value by single-chip microcomputer according to following formula (new instantaneous reactive power theory) calculates: $U=\sqrt{\frac{2}{3}}[u_a\mathrm{Sin}\left(\mathrm{\ωt}\right)+u_b\mathrm{Sin}(\mathrm{\ωt}-2\mathrm{\π}/3)+u_c\mathrm{Sin}(\mathrm{\ωt}+2\mathrm{\π}/3)]$ $I=\sqrt{\frac{2}{3}}[i_a\mathrm{Sin}\left(\mathrm{\ωt}\right)+i_b\mathrm{Sin}(\mathrm{\ωt}-2\mathrm{\π}/3)+i_c\mathrm{Sin}(\mathrm{\ωt}+2\mathrm{\π}/3)]$

Size according to the I value judges whether the fault that is short-circuited, promptly as I＞I _MaxThe time, there is short trouble to take place; When fault took place, single-chip microcomputer sent the failure wave-recording order, calculates each phase fault electric current, voltage effective value by single-chip microcomputer according to following formula: $I=\frac{1}{\mathrm{<figure-callout\; id="1"\; label="N\; K"\; filenames="C9710853900151.png"\; state="\{\{state\}\}">N</figure-callout>}}{K}_{}{}_1\underset{K=1}{\overset{N}{\mathrm{\&Sigma;}}}\left|i\left(K{T}_1\right)\right|$ $U=\frac{1}{\mathrm{<figure-callout\; id="1"\; label="N\; K"\; filenames="C9710853900151.png"\; state="\{\{state\}\}">N</figure-callout>}}{K}_{}{}_1\underset{K=1}{\overset{N}{\mathrm{\&Sigma;}}}\left|u\left(K{T}_1\right)\right|$

K wherein ₁Be scale-up factor, T ₁Be the sampling period, N is the sampling number of power frequency period, and i is the instantaneous value of circuit phase current, and u is the instantaneous value of circuit phase voltage.

The failure judgement type:

I _A＞I _Max, I _B＞I _Max, I _C＞I _MaxIt then is three-phase shortcircuit;

I _A＞I _Max, I _B＞I _MaxOr in the three-phase arbitrarily two-phase greater than I _Max, then be line to line fault;

I _A＞I _MaxOr in the three-phase any one greater than I _Max, then be single-phase short circuit;

U _A＜U _MinOr in the three-phase any one less than U _Min, then be singlephase earth fault.

3, by single-chip microcomputer the fault phase parameter is carried out Fourier analysis, and adopts curve fitting and rotating vector method to carry out the numerical value correction, obtain the real part and the imaginary part of fault phase voltage, current first harmonics component according to following formula: $U_{\mathrm{an}}=\frac{1}{N}\mathrm{\&Sigma;u}\left({\mathrm{KT}}_1\right)\mathrm{Cos}\left(\mathrm{\&omega;}{\mathrm{KT}}_1\right)$ $U_{\mathrm{bn}}=\frac{1}{N}\mathrm{\&Sigma;u}\left({\mathrm{KT}}_1\right)\mathrm{Sin}\left(\mathrm{\&omega;}{\mathrm{KT}}_1\right)$ $I_{\mathrm{an}}=\frac{1}{N}\mathrm{\&Sigma;i}\left({\mathrm{KT}}_1\right)\mathrm{Cos}\left(\mathrm{\&omega;}{\mathrm{KT}}_1\right)$ $I_{\mathrm{bn}}=\frac{1}{N}\mathrm{\&Sigma;i}\left({\mathrm{KT}}_1\right)\mathrm{Sin}\left(\mathrm{\&omega;}{\mathrm{KT}}_1\right)$

The angle error that rotating vector correction first and second mutual inductor brings: U _a=U _AnCos θ-U _BnSin θ U _b=U _BnCos θ+U _AnSin θ I _a=I _AnCos θ-I _BnSin θ I _b=I _BnCos θ+I _AnSin θ wherein θ is the angle error of mutual inductor.Reactance value: $X=\frac{U_b{I}_a-U_a{I}_b}{I_a^2+I_b^2}$ Thereby obtain distance value: $L=\frac{X}{x_1}$

Wherein: x ₁-this circuit unit length reactance value;

4, when being judged as singlephase earth fault, the operational grounding phase reversal switch; Closed isolated switch of non-ground connection and vacuum circuit breaker, make ground connection constitute alternate loop mutually with non-ground connection, simultaneously each line current, voltage are recorded ripple, carry out failure line selection and carry out distance calculation according to record ripple result then by above-mentioned 3 method, when demarcating fault distance, adopt the zero-sequence reactance value of unit length; Selection method: as the zero-sequence current i of certain bar circuit ₀=i _a+ i _b+ i _cDuring greater than setting, then this circuit is a faulty line.

According to above-mentioned fault test and distance-finding method, apparatus provided by the present invention has: transmitter, analog to digital conversion circuit, 80C196 single-chip microcomputer subsystem, demonstration, warning circuit, connected structure, double-deck casing is characterized in that: also have digital light every force driving circuit, from zeroing circuit, on-the-spot inching switch be installed in the ground connection phase reversal switch circuit of electric substation.Numeral photoelectricity quarantine enforcement driving circuit is connected between the output and single-chip microcomputer subsystem of analog to digital conversion circuit.Be connected with single-chip microcomputer from zeroing circuit, demonstration, warning circuit, on-the-spot trimming circuit, grounding switch control is connected with single-chip microcomputer output driving, and measuring-signal is sent into single-chip microcomputer through transmitter etc.Digital light is a raising system detection speed every forcing driving circuit (as shown in Figure 5) effect.Because transient process changes comparatively fast during short circuit, the sample rate of instrument to be had relatively high expectations, the data of gathering in the unit interval are many more, and the result who calculates is accurate more.And sample rate is except outside the Pass having with single-chip microcomputer, analog to digital conversion circuit etc., also be subjected to the restriction of photoelectric isolating device speed.And influence the principal element of speed often, experiment shows that the speed of forcing driving circuit can make photoelectric isolating device improves several times.Purpose from zeroing circuit is to improve the accuracy of Data Detection.In order to prevent that circuit from working long hours and drift appears in the variation of ambient temperature working point and to bring error to DATA REASONING, designed in the circuit from zeroing circuit (as shown in Figure 6), when detecting circuit and break down, instrument begins to record ripple, by zeroing circuit " zero point " of each road signal read in behind the record ripple, so just can revise, avoid the error that drift brought of instrument internal working point the data that record obtains during ripple.On-the-spot inching switch is used for the straightened up in place measuring accuracy, eliminates the slightly different errors of being brought of different circuit unit length reactance values.The purpose of ground connection phase reversal switch circuit is to make the singlephase earth fault of isolated neutral system constitute the measurement loop, makes reactance method can carry out fault localization and calculates.The ground connection phase reversal switch is connected on the bus of electric substation (as shown in Figure 7), when instrument is judged singlephase earth fault and taken place, controls another and carries out transient earthing mutually one time, constitutes two phase ground and measures the loop, by be out of order a little distance of instrument detecting.Owing to inserted current-limiting resistance, and circuit is short turn-on time, can not impact electrical network in the ground connection phase reversal switch circuit.Connected structure is convenient to the expansion of apparatus guarantee and measuring circuit quantity.Double-deck casing electric field shielding and magnetic field are to the influence of instrument.

Now that description of drawings is as follows:

Fig. 1: reactance method range finding substitutional connection principle schematic

Fig. 2; Software main program block diagram of the present invention

Fig. 3: apparatus theory diagram of the present invention

Fig. 4; Transmitter

Fig. 5: digital photoelectricity quarantine enforcement driving circuit

Fig. 6: from zeroing circuit

Fig. 7: ground connection phase reversal switch circuit

Fig. 8: apparatus wiring schematic diagram

Wherein:

Mutual inductor and measuring resistance and adjustable resistance are to change the small voltage signal that instrument can be handled into for three-phase voltage, current signal with input among Fig. 4, the circuit that each pin and other element of its core parts UA741 integrated operational amplifier is constituted forms one-level and penetrates the step voltage follower, plays the impedance conversion effect.

6N137 chip among Fig. 5 is to finish the critical piece that photoelectricity is isolated, and its pin such as 16 grade forces the base stage of the phototriode that drives to be joined with rising, be for increase light every frequency.

Fig. 6 is from zeroing circuit, and by the base stage of Single-chip Controlling triode, thereby the control zeroing actuating of relay is carried out zero point to recorder data and revised.

Fig. 7 is a ground connection phase reversal switch circuit, and this circuit is installed in electric substation, and its upper end joins G with bus A, the C of electric substation _A, G _CBe single-phase disconnector, DL is a single-phase vacuum circuit breaker, and LH is a current transformer, and R is a current-limiting resistance, and the lower end is connected with the substation ground net.

Fig. 8 is the wiring schematic diagram of instrument PLTC-1 of the present invention and test line, adopts modular design, the insertion slot type structure, and corresponding template of each bar outlet and corresponding the change are sent passage, and the effect between each dividing plate is separate.

The superiority that the present invention compares with prior art is:

(1), can the various types of short troubles of online detection, and accurately show and the trouble spot distance be not subjected to the influence of transition resistance and nonmetal short circuit.

(2), can solve the range finding difficult problem of the singlephase earth fault of isolated neutral system effectively.

(3), on method, adopted a series of measures, detect that time lag is little, good wave filtering effect, detection speed be fast.Proofread and correct and revised the angular difference and the ratio of mutual inductor, improved the measuring accuracy of apparatus effectively.

(4), adopted modular design, interchangeability is good, detection line quantity is not subjected to the restriction of this body structure of instrument.

(5), adopted redundancy, improved the reliability of apparatus.

The inventive method and apparatus are of great practical significance and wide application prospect for the fault localization of China's widely used 10-35KV single ended power supply high pressure overhead power line.

Claims (6)

1, a kind of online detection high pressure overhead power line fault distance-finding method based on the measuring circuit reactance value, is characterized in that:

(1), transmitter is three-phase voltage, the current signal introduced, after the standard signal conversion, send analog to digital conversion circuit;

When (2), sampling, by Single-chip Controlling, with the maintenance of sampling simultaneously of each road voltage and current signal, again by the Single-chip Controlling multi-way switch with signal after impedance matching, send the analog to digital conversion circuit conversion, the digital signal after the conversion is sent to the single-chip microcomputer subsystem through photoelectricity quarantine enforcement driving circuit; Carrying out normal effective value by single-chip microcomputer according to following formula (new instantaneous reactive power theory) calculates: $U=\sqrt{\frac{2}{3}}[u_a\mathrm{Sin}\left(\mathrm{\&omega;t}\right)+u_b\mathrm{Sin}(\mathrm{\&omega;t}-2\mathrm{\&pi;}/3)+u_c\mathrm{Sin}(\mathrm{\&omega;t}+2\mathrm{\&pi;}/3)]$ $I=\sqrt{\frac{2}{3}}[i_a\mathrm{Sin}\left(\mathrm{\&omega;t}\right)+i_b\mathrm{Sin}(\mathrm{\&omega;t}-2\mathrm{\&pi;}/3)+i_c\mathrm{Sin}(\mathrm{\&omega;t}+2\mathrm{\&pi;}/3)]$

Size according to the I value judges whether the fault that is short-circuited, promptly as I＞I _MaxThe time, there is short trouble to take place; When fault took place, single-chip microcomputer sent the failure wave-recording order, calculates each phase fault electric current, voltage effective value by single-chip microcomputer according to following formula: $I=\frac{1}{N}{K}_1\underset{K=1}{\overset{N}{\mathrm{\&Sigma;}}}\left|i\left(K{T}_1\right)\right|$ $U=\frac{1}{N}{K}_1\underset{K=1}{\overset{N}{\mathrm{\&Sigma;}}}\left|u\left({\mathrm{KT}}_1\right)\right|$

K wherein ₁Be scale-up factor, T ₁Be the sampling period, N is the sampling number of power frequency period, and i is the instantaneous value of circuit phase current, and u is the instantaneous value of circuit phase voltage;

(3), the fault phase parameter is carried out Fourier analysis, and adopt curve fitting and rotating vector method to carry out the numerical value correction, obtain the real part and the imaginary part of fault phase voltage, current first harmonics component according to following formula by single-chip microcomputer: $U_{\mathrm{an}}=\frac{1}{N}\mathrm{\&Sigma;u}\left({\mathrm{KT}}_1\right)\mathrm{Cos}\left(\mathrm{\&omega;}{\mathrm{KT}}_1\right)$ $U_{\mathrm{bn}}=\frac{1}{N}\mathrm{\&Sigma;u}\left({\mathrm{KT}}_1\right)\mathrm{Sin}\left(\mathrm{\&omega;}{\mathrm{KT}}_1\right)$ $I_{\mathrm{an}}=\frac{1}{N}\mathrm{\&Sigma;i}\left({\mathrm{KT}}_1\right)\mathrm{Cos}\left(\mathrm{\&omega;}{\mathrm{KT}}_1\right)$ $I_{\mathrm{bn}}=\frac{1}{N}\mathrm{\&Sigma;i}\left({\mathrm{KT}}_1\right)\mathrm{Sin}\left(\mathrm{\&omega;}{\mathrm{KT}}_1\right)$ The angle error that rotating vector correction I and II mutual inductor brings:

U _a＝U _anCosθ-U _bnSinθ U _b＝U _bnCosθ+U _anSinθ

I _a=I _AnCos θ-I _BnSin θ I _b=I _BnCos θ+I _AnSin θ reactance value: $X=\frac{U_b{I}_a-U_a{I}_b}{I_a^2+I_b^2}$

Thereby obtain distance value: $L=\frac{X}{x_1}$

Wherein: x ₁-this circuit unit length reactance value;

(4), when being judged as singlephase earth fault, operational grounding phase reversal switch: isolated switch of closed non-ground connection and vacuum circuit breaker, make ground connection constitute alternate loop mutually with non-ground connection, simultaneously each line current, voltage are recorded ripple, carry out failure line selection and carry out distance calculation according to record ripple result then by the method for above-mentioned (3), when demarcating fault distance, adopt the zero-sequence reactance value of unit length; Selection method: as the zero-sequence current i of certain bar circuit ₀=i _a+ i _b+ i _cDuring greater than setting, then this circuit is a faulty line.

2, a kind of online detection high pressure overhead power line fault distance-finding method according to claim 1 is characterized in that:

The standard of fault judgement is:

I _A＞I _Max, I _B＞I _Max, I _C＞I _MaxIt then is three-phase shortcircuit;

I _A＞I _Max, I _B＞I _MaxOr in the three-phase arbitrarily two-phase greater than I _Max, then be line to line fault;

I _A＞I _MaxOr in the three-phase any one greater than I _Max, then be single-phase short circuit;

U _A＜U _MinOr in the three-phase any one less than U _Min, then be singlephase earth fault.

3, a kind of online detection high pressure overhead power line fault distance-finding method according to claim 1 and the apparatus that designs, have: transmitter, analog to digital conversion circuit, digital light is characterized in that every forcing driving circuit, 80C196 single-chip microcomputer subsystem, demonstration, warning circuit: also have from zeroing circuit, on-the-spot trimming circuit and be installed in ground connection phase reversal switch circuit on electric substation's main circuit; Ground connection phase reversal switch circuit is made of two single-phase disconnectores, single-phase vacuum circuit breaker, current transformer, a current-limiting resistance, and its upper end is connected with A, the C of electric substation's main circuit bus, and the lower end is connected with the substation ground net; Numeral photoelectricity quarantine enforcement driving circuit is connected between the output and single-chip microcomputer subsystem of analog to digital conversion circuit, is connected with single-chip microcomputer from zeroing circuit, demonstration, warning circuit, on-the-spot trimming circuit; From the base stage of zeroing circuit, then amplify driving zeroing relay by the Single-chip Controlling triode; On-the-spot trimming circuit comes the on-the-spot reactance value of corresponding correction by 256 codings of 8 bit switches, B0～B7 the pin of 8 bus receivers/transmitter 74LS245 input end is connected with 1～8 pin of inching switch SW-DIP8 output terminal, and the pull-up resistor output terminal is in parallel with above-mentioned 8 pin; The control of ground connection phase reversal switch drives with single-chip microcomputer output and is connected, and measuring-signal is sent into single-chip microcomputer through transmitter.

4, a kind of online detection high pressure overhead power line according to claim 3 or network failure distance-finding method and the apparatus that designs, it is characterized in that: the circuit that each pin and other element of core parts UA741 integrated operational amplifier in the standard signal change-over circuit is constituted has formed the one-level of impedance conversion effect and has penetrated the step voltage follower.

5, a kind of online detection high pressure overhead power line according to claim 3 or network failure distance-finding method and the apparatus that designs is characterized in that: force to drive 16 pin such as grade of the 6N137 chip of digital light in circuit and the base stage of phototriode is joined.

6, a kind of online detection high pressure overhead power line according to claim 3 or network failure distance-finding method and the apparatus that designs, it is characterized in that: hardware circuit in the instrument and test line adopt module slot formula structure, corresponding template of each bar outlet and corresponding the change are sent passage, and the effect between each module is separate.

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