CN1228642C - Precisely Positioning method and device for power transmission line fault using multiple terminal signals - Google Patents

Abstract

The present invention relates to a transmission line fault positioning method which adopts multiple end signals. The present invention comprises the following steps: 1, voltage and current signal synchronized sampling on multiple ends of a transmission line is realized by using a GPS; 2, electrical quantities before and after a fault are recorded and exchanged for obtaining data which are required for positioning the fault; 3, the fault is positioned for obtaining the accurate position of a fault point: (1), judging the type of the fault, (2), positioning the fault accurately. The present invention also provides a device for positioning a fault in a transmission line, which comprises a voltage changer, a current transducer, a GPS signal collecting plate, a data acquisition card and an industrial control computer. The present invention can be used for positioning a fault which happens on a transmission line, the positioning accuracy is high, the influence of various factors on positioning errors is little, and the robustness is very good.

Description

A kind of accurate Fault Locating Method of transmission line of electricity that adopts the multiterminal signal

Technical field

The present invention relates to a kind of power transmission line fault locating method that adopts the multiterminal signal, belong to the transmission facility technical field.

Background technology

The transmission line malfunction location is the important measures that guarantee the power grid security economical operation, is that of field of power studies difficult point and focus.The existing fault localization method divides from principle, mainly contains traveling wave method and fault analysis method.

Localization of fault module on the fault wave recording device of Electric Industrial Equipment Co., Ltd.'s production both at home and abroad is to adopt one-sided electric current, voltage signal mostly at present, the mathematical model of using is to describe the algebraic equation of steady-state process, on principle, there is defective, can't eliminate the influence of transition resistance and peer-to-peer system increasing-aid current, the transient state process behavior of electric parameters in the time of can't the accurate description fault, therefore there is the deficiency on the principle in existing fault analyzing and positioning method, is subjected to influence of various factors, and positioning error is bigger.

Summary of the invention

Purpose of the present invention is exactly for addressing the above problem, a kind of method that adopts the accurate localization of fault of transmission line of electricity of multiterminal signal is provided, this method and device can position the fault that takes place on the transmission line of electricity, its bearing accuracy height, and positioning error is subjected to the influence of various factors little.

Technical scheme provided by the invention is: a kind of accurate Fault Locating Method of transmission line of electricity that adopts the multiterminal signal may further comprise the steps:

One, utilize GPS to realize voltage, the current signal synchronized sampling of transmission line of electricity multiterminal

1) voltage, the current signal to the transmission line of electricity secondary side is transformed into the low level that can gather and measure through superpotential, current transducer, the digital signal that becomes computing machine to handle through unscented transformation;

2) utilize GPS to realize the synchronized sampling of transmission line of electricity multiterminal, the electric parameters of being gathered is stamped markers;

Two, the electric parameters before and after record and the exchange trouble is to obtain the localization of fault desired data

1) according to the resulting signal of sampling, judges whether circuit breaks down, if the circuit non-fault then repeats above process; If break down, then begin to carry out failure wave-recording, voltage, the current data of circuit before and after the record trouble are stamped markers and are kept in the data file recorded data;

2) after data are preserved, the data that preserve each side transformer station clearing house;

Three, localization of fault is to obtain accuracy position of fault point:

1) failure judgement is separate

2) accurate localization of fault

At first, current and voltage quantities and parameter are carried out phase-model transformation; According to pairing fault type, select the line modulus mutually relevant for use with fault; According to Kirchhoff's second law, adopt the multiterminal electric parameters row of this line modulus to write the loop equation, try to achieve the trouble spot; Concrete performing step is as follows:

(1) row write out differential equation and the starting condition of describing fault front and back process

(2) current and voltage quantities and parameter are carried out phase-model transformation

(3), select the line modulus mutually relevant for use with fault according to pairing fault type;

(4) according to Kirchhoff's second law, adopt the multiterminal electric parameters row of this line modulus to write the loop equation, try to achieve the trouble spot

When single-phase earthing, line to line fault ground connection, phase fault or three-phase shortcircuit take place on the transmission line of electricity when

Ranging formula is: $p=\frac{u_{\mathrm{mn}}^s+R^s{i}_n^s+L^s\frac{d{i}_n^s}{\mathrm{dt}}}{R^s{i}_m^s+L^s\frac{d{i}_m^s}{\mathrm{dt}}+R^s{i}_n^s+L^s\frac{d{i}_n^s}{\mathrm{dt}}}$

Wherein:

P is the trouble spot apart from the number percent of the distance of transmission line of electricity one side the line is busy road total length;

i _m ^s, i _n ^s(s=α β) is respectively the electric current of s line modulus both sides;

R ^s, L ^s(s=α β) is respectively the resistance and the inductance of s line modulus correspondence;

u _Mn ^s(s=α β) is the voltage difference of s line modulus both sides;

In actual applications, should be with the ranging formula discretize, the later ranging formula of discretize is:

$p\left(k\right)=\frac{u_{\mathrm{mn}}^s\left(k\right)+R^s{i}_n^s\left(k\right)+L^s\frac{i_n^s\left(k\right)-i_n^s(k-1)}{\mathrm{\ΔT}}}{R^s{i}_m^s\left(k\right)+L^s\frac{i_m^s\left(k\right)-i_m^s(k-1)}{\mathrm{\ΔT}}+R^s{i}_n^s\left(k\right)+L^s\frac{i_n^s\left(k\right)-i_n^s(k-1)}{\mathrm{\ΔT}}}$

Wherein: p (k) is for being tried to achieve the number percent of trouble spot apart from the distance of transmission line of electricity one side the line is busy road total length by k-1 and k sampled value;

i _m ^s(k), i _n ^s(k) (s=α β) is respectively the electric current of k sampled point s line modulus both sides;

i _m ^s(k-1), i _n ^s(k-1) (s=α β) is respectively the electric current of k-1 sampled point s line modulus both sides;

R ^s, L ^s(s=α β) is respectively the resistance and the inductance of s line modulus correspondence;

u _Mn ^s(k) (s=α β) is the voltage difference of k sampled point s line modulus both sides;

Δ T is the sampling period.

The present invention can revise positioning result by condenser current compensation;

If the primary fault point that is calculated by above-mentioned ranging formula is respectively p apart from the number percent of two lateral extents ₀And 1-p ₀Come the electric capacity number percent of distributed lines both sides then according to this primary fault point, calculate the correcting current of considering to inject behind the capacitance current circuit, correcting current is substituted line current in the ranging formula, the correction result after just obtaining capacitance current compensated; Behind positioning result of every acquisition, all recomputate the number percent of distribution malfunctions point both sides capacitance, establish this and be respectively p with previous correction result according to the positioning result of the last time _iAnd p _I-1, repeat said process, up to satisfying | p _i-p _I-1| till＜the ε, the error amount of ε for setting.

The present invention also can handle with probabilistic method and least square method above-mentioned positioning result, and treatment step is as follows:

1) statistic law pre-service

Per two sampled points can calculate a positioning result, and several sampled points can calculate a plurality of Primary Location results, at first reject the invalid data in the PRELIMINARY RESULTS; The Primary Location result is carried out pre-service, remove bad data; Detailed process is as follows:

Account for the percentage of road total length completely because positioning result p (i) is trouble spot F to the line length of circuit one side, 0≤p (i)≤1 so p (i)＞0 or p (i)＜1 are invalid data, should give rejecting; Secondly, suppose that positioning result is the center with correct localization of fault result, is normal distribution: by the result that real electric current, voltage signal calculated, with higher probability distribution around correct localization of fault result; And by the result that electric current, voltage signal calculated who is interfered, then sparsely be distributed in less probability and depart from correct localization of fault result at a distance; According to this thought, the Primary Location result is carried out pre-service, remove bad data---keep the localization of fault result of high probability, remove localization of fault result than small probability.

2) ask the localization of fault result with least square method: above-mentioned ranging formula

$p\left(k\right)=\frac{u_{\mathrm{mn}}^s\left(k\right)+R^s{i}_n^s\left(k\right)+L^s\frac{i_n^s\left(k\right)-i_n^s(k-1)}{\mathrm{\ΔT}}}{R^s{i}_m^s\left(k\right)+L^s\frac{i_m^s\left(k\right)-i_m^s(k-1)}{\mathrm{\ΔT}}+R^s{i}_n^s\left(k\right)+L^s\frac{i_n^s\left(k\right)-i_n^s(k-1)}{\mathrm{\ΔT}}}$

Represent molecule, the denominator polynomial expression of ranging formula respectively with Y and X, ranging formula can comprehensively be:

$p=\frac{Y}{X}$ Can be write as Y=pX

The least square solution of P is:

P＝(X ^TX) ^-1X ^TY

P according to following formula calculates obtains X ' with Y as known quantity conversely, makes Z=X ', and Z is auxiliary variable, and revised location Calculation result is with auxiliary variable method:

P′＝(Z ^TX) ^-1Z ^TY。

The present invention also provides a kind of transmission line malfunction locating device, comprise voltage on the transmission line of electricity, the voltage of Current Transformer Secondary side, electrorheological changes the low level voltage changer that adapts with the self-adapting data collection plate into, current transducer, the low level signal of simulation is transformed into the V/F plate of the digital quantity that computing machine can handle, be used to receive gps signal and target gps signal dash receiver when the digital quantity of being gathered stamped, gather the data collecting card of the digital quantity that the V/F plate changed, read in the industrial control computer of the electric parameters that data collecting card gathers by isa bus; Wherein the output of voltage current transformer connects the input of voltage transmitter, current transducer, the output of voltage transmitter, current transducer connects the input of V/F plate, the output of V/F plate, gps signal dash receiver connects the input of data collecting card, and the output of data collecting card connects the input of industrial control computer by isa bus.

The present invention proposes a kind of accurate Fault Locating Method of transmission line of electricity and device of employing multiterminal signal of novelty, its basic ideas are: electric current, voltage and line parameter circuit value are carried out phase-model transformation; According to pairing fault type, select the line modulus relevant for use with fault; According to element characteristic and Kirchhoff's law, adopt the line modulus row of multiterminal electric parameters to write the loop differential equation, because what adopt is the line modulus of electric signal and line parameter circuit value, can avoid soil conductivity in the ground return circuit to change and factor such as Changes in weather for the considerable influence of positioning result; Adopt the differential equation to replace in the existing Fault Locating Method employed algebraic equation, can describe transient state process and feature after the fault well, avoid the aperiodic component of decaying influence for positioning result as mathematical model; Utilize the accurate time dissemination system of GPS to guarantee the synchronism of data.For the fault that is taken place on the increasing long distance transmission line in the electric system, the condenser current compensation method that the present invention proposes can make the localization of fault precision improve greatly.Theoretically, the differential equation of first order method only needs the sampled value in two moment just can calculate the trouble spot, thereby in whole failure process, can draw many positioning results, and when practical application, because operating mode complexity, the fault data of sampling may be polluted, and needs these positioning results are carried out the pre-service of statistical method.Because the number of discrete back equation is much larger than the number of unknown number, be overdetermined equation, can adopt least square method, probabilistic method and least square disposal route that the present invention proposes can be rejected because of null result that factor produced such as sampling errors, and guarantee that final positioning result is accurately reliable.This method and device can position the fault that takes place on the transmission line of electricity, its bearing accuracy height, and positioning error is subjected to the influence of various factors very little, has extraordinary robustness.

Description of drawings:

Accompanying drawing is a fault locator structural representation of the present invention.

Embodiment

The present invention includes following each several part:

One, part of data acquisition

1) voltage of transmission line of electricity secondary side, current signal are transformed into the low level that can gather and measure through superpotential, current transducer, collect the digital signal that computing machine can be handled through digital to analog conversion (A/D or V/F conversion) and sampling card;

2) in locating device, utilize gps signal to receive receiver module and obtain the pulse per second (PPS) of error, the electric parameters of being gathered is stamped markers less than 50nS;

3) electric current, the voltage digital signal that collects according to the sampling card judges whether circuit breaks down, if the circuit non-fault then repeats above process; If break down, the electric parameters that then writes down and preserve the fault front and back arrives hard disk to obtain the localization of fault desired data; The available criterion that has proposed takes place in failure judgement, also available following criterion: (1) overcurrent starts: utilize relatively (2) negative-sequence current startup of current phasor measurement value and phase current setting valve: negative-sequence current calculated value and negative-sequence current setting valve are compared, if the phase current calculated value, is then thought and is broken down greater than the negative-sequence current setting valve greater than phase current setting valve or negative-sequence current calculated value; Overcurrent start with negative-sequence current start with or logic form comprehensive criterion, arbitrary condition satisfies then and starts.

Two, data recording is preserved and switching part

1) work as line failure, locating device starts and also to begin to carry out failure wave-recording, and voltage, the current data of circuit in the certain hour before and after the record trouble are stamped in the data file that markers is kept at hard disk recorded data.

2) data are preserved the data that preserve each side transformer station clearing house, back, obtain the information of each the substation's recorded and stored of back that breaks down after, all available localization of fault formula proposed by the invention calculates abort situation on arbitrary localization of fault background computer.

Three, separate judgement of fault type and location Calculation

1) failure judgement zone and separate

The separate criterion of the separate available more existing faults of failure judgement also can realize by following step: locating device is installed in the two ends of circuit, and makes the reference direction of both sides electric current flow to circuit by bus.If the electric current of both sides is zero after by the reference direction addition, show that then circuit normally moves (when circuit normally moves, the electric current of both sides by should be zero after the reference direction addition); If the electric current of both sides is not equal to zero after by the reference direction addition, then show line-internal break down (electric current that both sides record when the line-internal fault is all for flowing to circuit by bus, must be not equal to their results after by the reference direction addition zero).Regard three-phase as three and single-phasely can obtain the result to each processing of carrying out mutually as above respectively: if A phase ground connection, then B is non-fault phase with C mutually mutually, the corresponding respectively addition of the three-phase current of both sides must be that the A phase current is non-vanishing, and B is zero with C electric current mutually mutually; If A is the fault phase with B mutually mutually, after handling with quadrat method, it is non-vanishing to obtain A phase and B phase current, and the electric current of C phase is zero; The three-phase fault conclusion is that the electric current of three-phase is all non-vanishing.

2) accurate localization of fault

At first, row write out the differential equation of describing circuit transient state, and current and voltage quantities and parameter are carried out phase-model transformation; According to pairing fault type, select the line modulus mutually relevant for use with fault; Write the differential equation of outlet modulus,, adopt the both-end electric parameters row of this line modulus to write the loop equation, can try to achieve the trouble spot according to Kirchhoff's second law.

I: earlier the current and voltage quantities and the parameter of circuit are carried out phase-model transformation

Owing to have the coupling of mutual inductance, mutual resistance and mutual capacitance between the loop of three phase line, therefore, before to the three phase line analysis, can carry out decoupling zero earlier.Three-phase or multiphase coupled equation are transformed to a plurality of independent equations find the solution, the phase-model transformation matrix of voltage, electric current is designated as T respectively _u, T _iThe two equates for even transposition circuit, satisfies relational expression for the circuit that do not replace

T _u ^-1＝T _i ^T

V _m＝T _u ^-1V， I _m＝T _i ^-1I

Through phase-model transformation, modulus resistor matrix R _m=T _u ^-1RT _i=T _i ^TRT _iBe diagonal matrix, in like manner modulus inductance matrix L _m, capacitance matrix C _mBe diagonal matrix, that is to say that the voltage of each pattern, electric current only interrelate by resistance, inductance or the electric capacity of corresponding modes, and irrelevant with the amount of other pattern.This shows that above-mentioned phase-model transformation has been eliminated alternate coupling really, do not have coupling between the modulus that decomposites.

A) choose the Karenbauer conversion as the phase-model transformation matrix

$\left[\begin{array}{c}{i}_0\\ i_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]=\frac{1}{3}\left[\begin{array}{ccc}1& 1& 1\\ 1& -1& 0\\ 1& 0& -1\end{array}\right]\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]$

This current transformation is A, B, and three phasor currents of C are converted to 0, α, three modulus electric currents of β, the voltage transformation equation is similar.

The resistance and the inductance matrix of phasor are respectively

Then the resistance of modulus and inductance matrix are

R in the formula ₀=R _s+ 2R _m, R _α=R _β=R _s-R _m, L ₀=L _s+ 2L _m, L _a=L _β=L _s-L _m

II: calculate the trouble spot

When single-phase earthing, line to line fault ground connection, phase fault or three-phase shortcircuit take place on the transmission line of electricity when

Ranging formula is: $p=\frac{u_{\mathrm{mn}}^s+R^s{i}_n^s+L^s\frac{d{i}_n^s}{\mathrm{dt}}}{R^s{i}_m^s+L^s\frac{d{i}_m^s}{\mathrm{dt}}+R^s{i}_n^s+L^s\frac{d{i}_n^s}{\mathrm{dt}}}$

Wherein:

P is the trouble spot apart from the number percent of the distance of transmission line of electricity one side the line is busy road total length;

i _m ^s, i _n ^s(s=α β) is respectively the electric current of s line modulus both sides;

R ^s, L ^s(s=α β) is respectively the resistance and the inductance of s line modulus correspondence;

u _Mn ^s(s=α β) is the voltage difference of s line modulus both sides.

In the application of reality, use the ranging formula of discretize, the later ranging formula of discretize is:

$p\left(k\right)=\frac{u_{\mathrm{mn}}^s\left(k\right)+R^s{i}_n^s\left(k\right)+L^s\frac{i_n^s\left(k\right)-i_n^s(k-1)}{\mathrm{\ΔT}}}{R^s{i}_m^s\left(k\right)+L^s\frac{i_m^s\left(k\right)-i_m^s(k-1)}{\mathrm{\ΔT}}+R^s{i}_n^s\left(k\right)+L^s\frac{i_n^s\left(k\right)-i_n^s(k-1)}{\mathrm{\ΔT}}}$

Wherein: p (k) is for being tried to achieve the number percent of trouble spot apart from the distance of transmission line of electricity one side the line is busy road total length by k-1 and k sampled value;

i _m ^s(k), i _n ^s(k) (s=α β) is respectively the electric current of k sampled point s line modulus both sides;

i _m ^s(k-1), i _n ^s(k-1) (s=α β) is respectively the electric current of k-1 sampled point s line modulus both sides;

R ^s, L ^s(s=α β) is respectively the resistance and the inductance of s line modulus correspondence;

u _Mn ^s(k) (s=α β) is the voltage difference of k sampled point s line modulus both sides;

Δ T is the sampling period.

For taking into account capacitance current, utilize condenser current compensation correction positioning result than long transmission line.Modification method is as follows: establish i ^s _CmAnd i ^s _CnBe respectively the electric capacity charging s mould electric current of both sides, trouble spot, i ^s _mAnd i ^s _nBe respectively the electric current that the both sides power supply injects circuit, i ^s _XmAnd i ^s _XnBe respectively the correcting current that injects circuit behind the consideration capacitance current, promptly

i ^α _Xm＝i ^α _m-i ^α _Cm

i ^α _Xn＝i ^α _n-i ^α _Cn

Line current in the above-mentioned ranging formula is replaced with correcting current.Because the shunting of the electric capacity of both sides is relevant with position of failure point, at first calculates a primary fault position with ranging formula, distributes the electric capacity number percent of both sides then according to this primary fault point.

The primary fault point that design is calculated is respectively p apart from the number percent of two lateral extents ₀And 1-p ₀, because the also identical proportional distribution of electric capacity of both sides, so the capacitance current of both sides is respectively:

${i^{\mathrm{\α}}}_{\mathrm{Cm}}=p_0{C}_1\frac{d{u^{\mathrm{\α}}}_m}{\mathrm{dt}}---{i^{\mathrm{\α}}}_{\mathrm{Cn}}=(1-p_0)C_1\frac{d{u^{\mathrm{\α}}}_n}{\mathrm{dt}}$

The correcting current of both sides is respectively:

i ^α _Xm＝i ^α _m-i ^α _Cm i ^α _Xn＝i ^α _n-i ^α _Cn

With the line current in the alternative above-mentioned ranging formula of correcting current.Can obtain revised ranging formula:

$p_0=\frac{u_{\mathrm{mn}}^s+R^s[i_n^s-(1-p_0)\frac{C_1}{2}\frac{d{u}_n^s}{\mathrm{dt}}]+L^s\frac{d[i_n^s-(1-p_0)\frac{C_1}{2}\frac{d{u}_n^s}{\mathrm{dt}}]}{\mathrm{dt}}}{R^s(i_m^s-p_0{C}_1\frac{d{u}_s^m}{\mathrm{dt}})+L^s\frac{d(i_m^s-p_0\frac{C_1}{2}\frac{d{u}_m^s}{\mathrm{dt}})}{\mathrm{dt}}+R^s[i_n^s-(1-p_0)\frac{C_1}{2}\frac{d{u}_n^s}{\mathrm{dt}}]+L^s\frac{d(i_n^s-(1-p_0)\frac{C_1}{2}\frac{d{u}_n^s}{\mathrm{dt}})}{\mathrm{dt}}}$

This is the nonlinear equation about p, adopts solution by iterative method, and iteration is till satisfying following condition.

| p _k-p _K-1| the error amount of＜ε ε for setting;

The location PRELIMINARY RESULTS that obtains is previously carried out probabilistic method and Least Square in Processing theoretically, the differential equation of first order method only needs the sampled value in two moment just can calculate the trouble spot, thereby in whole failure process, can draw many p values, and when practical application, because operating mode complexity, the fault data of sampling may be polluted, and needs these positioning results are carried out the pre-service of statistical method.Because the number of discrete back equation is overdetermined equation much larger than the number of unknown number, this method adopts least square method to find the solution.

The treatment step of positioning result:

1. statistic law pre-service

For PRELIMINARY RESULTS, at first must reject invalid data.Account for the percentage of all fronts road total length because positioning result p (k) is trouble spot F to the line length of circuit one side, so 0≤p (k)≤1 is arranged,, should give rejecting so p (k)＞0 or p (k)＜1 are invalid data.Secondly, have reason to suppose that these results are the center with correct localization of fault result, be normal distribution: by the result that real electric current, voltage signal produced, with higher probability distribution around true value; And by the result that undesired signal produced, then sparsely be distributed in less probability and depart from true value at a distance.According to this thought, the Primary Location result is carried out pre-service, remove bad data.

2. ask the localization of fault result with least square method

Ranging formula

$p\left(k\right)=\frac{u_{\mathrm{mn}}^s\left(k\right)+R^s{i}_n^s\left(k\right)+L^s\frac{i_n^s\left(k\right)-i_n^s(k-1)}{\mathrm{\ΔT}}}{R^s{i}_m^s\left(k\right)+L^s\frac{i_m^s\left(k\right)-i_m^s(k-1)}{\mathrm{\ΔT}}+R^s{i}_n^s\left(k\right)+L^s\frac{i_n^s\left(k\right)-i_n^s(k-1)}{\mathrm{\ΔT}}}$

Represent molecule, the denominator polynomial expression of ranging formula respectively with Y and X, ranging formula can comprehensively be:

$p=\frac{Y}{X}$ Or write as Y=pX

Then the least square solution of positioning result P is:

P＝(X ^TX) ^-1X ^TY

P according to following formula calculates obtains X ' with Y as known quantity conversely, makes Z=X ', and Z is auxiliary variable; Revised location Calculation result is with auxiliary variable method:

P′＝(Z ^TX) ^-1Z ^TY

Introduce the relative section (referring to accompanying drawing) of fault locator among the present invention below in detail:

1) isolated variable and V/F part

The high voltage of transmission line of electricity A, B, C three-phase, big electric current are transformed into low-voltage and little electric current by the voltage transformer (VT) on the transmission line of electricity (TV), current transformer (TA); Isolated variable is with voltage, current transducer the low-voltage of voltage, Current Transformer Secondary side to be transformed into the low level that collecting part is suitable for.Pass to Computer Processing after collecting digital quantity by the V/F conversion.Wherein the selected transmitter of isolated variable should have higher conversion precision and less response time.Current transducer also should have saturation characteristic preferably.

Each device input n road analog quantity (n road voltage, n road electric current) becomes pulse signal through the signal Processing case earlier and enters PC plug-in unit (expansion board) again.The V/F transducer is selected the VFC110 chip that present full scale frequency is the highest, the linearity is good for use, and error is about 2 ^-12

2) gps clock receiving unit

The GPS receiver is made up of receiver module and antenna.Receiver can receive its 4～8 satellites at any time simultaneously, its internal hardware circuit and process software are by decoding to the received signal and handling, can therefrom extract and export two kinds of time signals: the one, be spaced apart the pulse signal of 1s, be 1PPS (1pulse per second), the synchronous error of its pulse front edge and universal time (Greenwich Mean Time) is no more than 50nS; The 2nd, the message through the output of RS-232 serial port comprises corresponding universal time of 1PPS pulse front edge and date code (year, month, day, hour, min, second).

Synchronized sampling principle based on GPS is such: the oscillator that is made of the high precision crystal oscillator can produce the clock signal that satisfies the sampling rate requirement through frequency division, it every one second by the calibration of the standard second pulse signal of GPS once guarantees that the forward position and the GPS pulse per second (PPS) of the pulse signal that oscillator is exported is synchronous.The circuit both sides all go to control separately data acquisition with process the clock signal synchronous of oscillator output as sampling pulse, and it is synchronous therefore sampling.The GPS receiver is given industrial computer through standard serial port with timing code, is used for to sampled data with " time tag ", to be used for the data transmission and to handle.

3) principle of work of data collecting card

Data collecting card is an expansion board of inserting the industrial computer isa bus, and the major function of data collecting card has:

1. receive the instruction of PC about sample frequency

2.PC machine can be to the expansion board reset operation;

3. expansion board is to the duty of PC report self-detection result and GPS dash receiver;

Expansion board have perfect self check with from reset function;

5. 8 tunnel analog quantitys are carried out analog to digital conversion according to the instruction of PC with the sampling rate of 0.25ms, and stamp markers, can carry out pre-service to data in case of necessity:

6.A/D conversion resolution is near 2 ^-12

Claims (3)

1. accurate Fault Locating Method of transmission line of electricity that adopts the multiterminal signal may further comprise the steps:

(1) utilize GPS to realize voltage, the current signal synchronized sampling of transmission line of electricity multiterminal

1) voltage, the current signal to the transmission line of electricity secondary side is transformed into the low level that can gather and measure through superpotential, current transducer, the digital signal that becomes computing machine to handle through unscented transformation;

2) utilize GPS to realize the synchronized sampling of transmission line of electricity multiterminal, the electric parameters of being gathered is stamped markers;

(2) electric parameters before and after record and the exchange trouble is to obtain the localization of fault desired data

1) according to the resulting signal of sampling, judges whether circuit breaks down, if the circuit non-fault then repeats above process; If break down, then begin to carry out failure wave-recording, voltage, the current data of circuit before and after the record trouble are stamped markers and are kept in the data file recorded data;

2) after data are preserved, the data that preserve each side transformer station clearing house;

(3) localization of fault is to obtain accuracy position of fault point:

1) failure judgement is separate

2) accurate localization of fault

At first, current and voltage quantities and parameter are carried out phase-model transformation; According to pairing fault type, select the line modulus mutually relevant for use with fault; According to Kirchhoff's second law, adopt the multiterminal electric parameters row of this line modulus to write the loop equation, try to achieve the trouble spot; Concrete performing step is as follows:

(1) row write out differential equation and the starting condition of describing fault front and back process

(2) current and voltage quantities and parameter are carried out phase-model transformation

(3), select the line modulus mutually relevant for use with fault according to pairing fault type;

(4) according to Kirchhoff's second law, adopt the multiterminal electric parameters row of this line modulus to write the loop equation, try to achieve the trouble spot

When single-phase earthing, line to line fault ground connection, phase fault or three-phase shortcircuit take place on the transmission line of electricity when

Ranging formula is: $p=\frac{u_{\mathrm{mn}}^s+R^s{i}_n^s+L^s\frac{d{i}_n^s}{\mathrm{dt}}}{R^s{i}_m^s+L^s\frac{d{i}_m^s}{\mathrm{dt}}+R^s{i}_n^s+L^s\frac{{\mathrm{di}}_n^s}{\mathrm{dt}}}$

Wherein:

P is the trouble spot apart from the number percent of the distance of transmission line of electricity one side the line is busy road total length;

i _m ^s, i _n ^s(s=α β) is respectively the electric current of s line modulus both sides;

R ^s, L ^s(s=α β) is respectively the resistance and the inductance of s line modulus correspondence;

u _Mn ^s(s=α β) is the voltage difference of s line modulus both sides;

In actual applications, should be with the ranging formula discretize, the later ranging formula of discretize is:

$p\left(k\right)=\frac{u_{\mathrm{mn}}^s\left(k\right)+R^s{i}_n^s\left(k\right)+L^s\frac{i_n^s\left(k\right)-i_n^s(k-1)}{\mathrm{\ΔT}}}{R^s{i}_m^s+L^s\frac{i_m^s\left(k\right)-i_m^s(k-1)}{\mathrm{\ΔT}}+R^s{i}_n^s\left(k\right)+L^s\frac{i_n^s\left(k\right)-i_n^s(k-1)}{\mathrm{\ΔT}}}$

Wherein: p (k) is for being tried to achieve the number percent of trouble spot apart from the distance of transmission line of electricity one side the line is busy road total length by k-1 and k sampled value;

i _m ^s(k), i _n ^s(k) (s=α β) is respectively the electric current of k sampled point s line modulus both sides;

i _m ^s(k-1), i _n ^s(k-1) (s=α β) is respectively the electric current of k-1 sampled point s line modulus both sides;

R ^s, L ^s(s=α β) is respectively the resistance and the inductance of s line modulus correspondence;

u _Mn ^s(k) (s=α β) is the voltage difference of k sampled point s line modulus both sides;

Δ T is the sampling period.

2. localization method according to claim 1 is characterized in that: utilize condenser current compensation to revise positioning result;

If the primary fault point that is calculated by above-mentioned ranging formula is respectively p apart from the number percent of two lateral extents ₀And 1-p ₀Come the electric capacity number percent of distributed lines both sides then according to this primary fault point, calculate the correcting current of considering to inject behind the capacitance current circuit, correcting current is substituted line current in the ranging formula, the correction result after just obtaining capacitance current compensated; Behind positioning result of every acquisition, all recomputate the number percent of distribution malfunctions point both sides capacitance, establish this and be respectively p with previous correction result according to the positioning result of the last time _iAnd p _I-1, repeat said process, up to satisfying | p _i-p _I-1| till＜the ε, the error amount of ε for setting.

3. localization method according to claim 1 and 2 is characterized in that: after obtaining positioning result, these results are handled with probabilistic method and least square method, treatment step is as follows:

1) statistic law pre-service

Per two sampled points can calculate a positioning result, and several sampled points can calculate a plurality of Primary Location results, at first reject the invalid data in the PRELIMINARY RESULTS; The Primary Location result is carried out pre-service, remove bad data; Detailed process is as follows:

Account for the percentage of road total length completely because positioning result p (i) is trouble spot F to the line length of circuit one side, 0≤p (i)≤1 so p (i)＞0 or p (i)＜1 are invalid data, should give rejecting; Secondly, suppose that positioning result is the center with correct localization of fault result, is normal distribution: by the result that real electric current, voltage signal calculated, with higher probability distribution around correct localization of fault result; And by the result that electric current, voltage signal calculated who is interfered, then sparsely be distributed in less probability and depart from correct localization of fault result at a distance; According to this thought, the Primary Location result is carried out pre-service, remove bad data---keep the localization of fault result of high probability, remove localization of fault result than small probability;

1) asks the localization of fault result with least square method

Above-mentioned ranging formula

$p\left(k\right)=\frac{u_{\mathrm{mn}}^s\left(k\right)+R^s{i}_n^s\left(k\right)+L^s\frac{i_n^s\left(k\right)-i_n^s(k-1)}{\mathrm{\ΔT}}}{R^s{i}_m^s+L^s\frac{i_m^s\left(k\right)-i_m^s(k-1)}{\mathrm{\ΔT}}+R^s{i}_n^s\left(k\right)+L^s\frac{i_n^s\left(k\right)-i_n^s(k-1)}{\mathrm{\ΔT}}}$

Represent molecule, the denominator polynomial expression of ranging formula respectively with Y and X, ranging formula can comprehensively be:

$p=\frac{Y}{X}$ Can be write as Y=pX

The least square solution of P is:

P＝(X ^TX) ^-1X ^TY

P according to following formula calculates obtains X ' with Y as known quantity conversely, makes Z=X ', and Z is auxiliary variable, and revised location Calculation result is with auxiliary variable method:

P′＝(Z ^TX) ^-1Z ^TY。

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