CN103323748A - System and method for recognizing power cable fault based on fractal and wavelet transform - Google Patents

Abstract

The invention discloses a system and method for recognizing a power cable fault based on fractal and wavelet transform. The system comprises a current detection circuit module, a signal modulation circuit module, a data collecting card and a master control computer which are connected in sequence, wherein the current detection circuit module comprises an A-phase hall current sensor, a B-phase hall current sensor and a C-phase hall current sensor, and the signal modulation circuit module comprises an A-phase I/V switching circuit module, a B-phase I/V switching circuit module, a C-phase I/V switching circuit module, an A-phase signal amplifying circuit module, a B-phase signal amplifying circuit module, a C-phase signal amplifying circuit module, an A-phase filter circuit module, a B-phase filter circuit module and a C-phase filter circuit module. The method comprises the following steps that signals are detected in real time and uploaded synchronously; the signals are collected and saved; the cable fault is recognized. The system and method for recognizing the power cable fault based on the fractal and the wavelet transform has the advantages of being novel and reasonable in design, high in detection precision, stability and reliability due to the fact that the hall current sensors are adopted to detect the cable current, capable of easily, rapidly, accurately and effectively recognizing the type of cable short fault by means of the combination of the fractal method and the wavelet transform method, strong in practicability, good in using effect and convenient to popularize and use.

Description

Based on fractal and power cable fault recognition system and method wavelet transformation

Technical field

The present invention relates to cable fault recognition technology field, especially relate to a kind of based on fractal and power cable fault recognition system and method wavelet transformation.

Background technology

The power cable transmission line of electricity is the important step in the electric system, is the middle hinge zone that connects power plant and user.Because power cable is long-term buried in underground, be subject to the variation of soil environment, so operation troubles very easily occurs, cable is in actual motion, various faults and irregular operating state may occur, the most common while also is that the most dangerous fault is the short circuit that various types occurs, and short trouble comprises single-phase grounding fault, line to line fault, two-phase short circuit and ground fault and three phase short circuit fault etc.In power cable fault detection and Identification field, what extensively adopt is the protective relaying device of reflection power frequency quality at present, and current transformer is adopted in the detection of cable current signal usually, and wavelet analysis method is adopted in the power cable fault signal analysis usually.

When cable is short-circuited fault, what cable fault produced is the high frequency transient travelling wave signal, travelling wave signal is a full frequency-domain signal, and the frequency of the transient state travelling wave signal of cable fault moment generation mainly is distributed between the 10-100KHz, and our present common current transformer is that the primary and secondary winding carries out electromagnetic coupled by iron core, and primary and secondary current ratio is identical with the turn ratio.Be used for measuring the sine-wave current of 40-20kHz, obviously can not satisfy the requirement of obtaining cable fault high frequency travelling wave signal, will lose some high-frequency datas of a lot of fault transient signals with its secondary side signal that carries out obtaining after electric weight conversion and the signal condition, follow-up data are processed and the analysis of fault detect link thereby affect; Because the imperfection of mutual inductor, so that all there are larger error in no-load voltage ratio and phase measurement, survey frequency is limited.Often need to adopt the method compensation of hardware or software, the complexity that when having increased Systems balanth system is become.

In the power cable fault signal analysis, wavelet analysis has the feature of time-frequency domain localization, can give prominence to by the flexible variation of time-frequency window the mutagenic components of fault-signal, can effectively extract the fault-signal characteristic information.Have at present many methods that adopt many wavelet decomposition to carry out fault detect, although these methods have been carried out some improvement to the Algorithms of Wavelet Analysis in the noise, but still be difficult for to realize that temporal signatures is changed to main disturbance to be differentiated, can't be rapidly, exactly 10 kinds of common short troubles are carried out Classification and Identification.

Summary of the invention

Technical matters to be solved by this invention is for above-mentioned deficiency of the prior art, provide a kind of simple in structure, novel in design rationally, high, the stability of precision and the high power cable fault recognition system based on fractal and wavelet transformation of reliability.

For solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of based on fractal and power cable fault recognition system wavelet transformation, it is characterized in that: comprise the current detection circuit module of joining successively, the signal conditioning circuit module, data collecting card and main control computer, described current detection circuit module comprises the A phase Hall current sensor that detects in real time for the A phase current to threephase cable, be used for the B phase Hall current sensor that the B phase current to threephase cable detects in real time and be used for mutually Hall current sensor of C that the C phase current to threephase cable detects in real time, described signal conditioning circuit module comprises the A phase current signal conditioning circuit module of nursing one's health for to the signal of A phase Hall current sensor output, be used for B phase current signal conditioning circuit module that the signal of B phase Hall current sensor output is nursed one's health and be used for the C phase current signal conditioning circuit module nursed one's health of the signal of Hall current sensor output mutually to C, described A phase current signal conditioning circuit module is by the A phase I/V change-over circuit module of joining successively, A phase signals amplifying circuit module and A mutually filter circuit module consist of, described B phase current signal conditioning circuit module is by the B phase I/V change-over circuit module of joining successively, B phase signals amplifying circuit module and B mutually filter circuit module consist of, and described C phase current signal conditioning circuit module is by the C phase I/V change-over circuit module of joining successively, C phase signals amplifying circuit module and C mutually filter circuit module consist of.

Above-mentioned based on fractal and power cable fault recognition system wavelet transformation, it is characterized in that: described A phase Hall current sensor is the first closed loop Hall current sensor CHB-25NP, described the first closed loop Hall current sensor CHB-25NP is connected on the A phase line of cable by pin 1 and pin 6, pin 2 and its pin 10 of described the first closed loop Hall current sensor CHB-25NP join, pin 3 and its pin 9 of described the first closed loop Hall current sensor CHB-25NP join, pin 4 and its pin 8 of described the first closed loop Hall current sensor CHB-25NP join, pin 5 and its pin 7 of described the first closed loop Hall current sensor CHB-25NP join, pin 12 and the positive supply VCC of described the first closed loop Hall current sensor CHB-25NP join, and pin 13 and the negative supply-VCC of described the first closed loop Hall current sensor CHB-25NP join;

Described A phase I/V change-over circuit module is made of resistance R 1a, and the pin 11 of the end of described resistance R 1a and the first closed loop Hall current sensor CHB-25NP joins, the other end ground connection of described resistance R 1a;

Described A phase signals amplifying circuit module is by the first operational amplifier chip OP07CP, resistance R 2a, R3a, R4a and R5a, and diode D1a and D2a form; The pin 2 of described the first operational amplifier chip OP07CP and the end of resistance R 2a, the end of resistance R 4a, the positive pole of the negative pole of diode D1a and diode D2a joins, the end of the other end of described resistance R 2a and resistance R 1a joins, the pin 3 of described the first operational amplifier chip OP07CP and the end of resistance R 3a, the negative pole of the positive pole of diode D1a and diode D2a joins, the other end ground connection of described resistance R 3a, pin 4 and the negative supply-VCC of described the first operational amplifier chip OP07CP join, pin 7 and the positive supply VCC of described the first operational amplifier chip OP07CP join, and the pin 6 of described the first operational amplifier chip OP07CP joins with the other end of resistance R 4a and the end of resistance R 5a;

Described A phase filter circuit module is by resistance R 6a, inductance L 1a, L2a, L3a, L4a, L5a, L6a and L7a, and capacitor C 1a, C2a and C3a form; The end of described inductance L 1a and the other end of resistance R 5a join, the end of the end of described inductance L 2a and the other end of inductance L 1a and inductance L 5a joins, the other end of described inductance L 5a is by capacitor C 1a ground connection, the end of the end of described inductance L 3a and the other end of inductance L 2a and inductance L 6a joins, the other end of described inductance L 6a is by capacitor C 2a ground connection, the end of the end of described inductance L 4a and the other end of inductance L 3a and inductance L 7a joins, the other end of described inductance L 7a is by capacitor C 3a ground connection, the other end of described inductance L 4a is by resistance R 6a ground connection, and the other end of described inductance L 4a is the output terminals A-OUT of described A phase filter circuit module and joins with the signal input part of data collecting card.

Above-mentioned based on fractal and power cable fault recognition system wavelet transformation, it is characterized in that: described B phase Hall current sensor is the second closed loop Hall current sensor CHB-25NP, described the second closed loop Hall current sensor CHB-25NP is connected on the B phase line of cable by pin 1 and pin 6, pin 2 and its pin 10 of described the second closed loop Hall current sensor CHB-25NP join, pin 3 and its pin 9 of described the second closed loop Hall current sensor CHB-25NP join, pin 4 and its pin 8 of described the second closed loop Hall current sensor CHB-25NP join, pin 5 and its pin 7 of described the second closed loop Hall current sensor CHB-25NP join, pin 12 and the positive supply VCC of described the second closed loop Hall current sensor CHB-25NP join, and pin 13 and the negative supply-VCC of described the second closed loop Hall current sensor CHB-25NP join;

Described B phase I/V change-over circuit module is made of resistance R 1b, and the pin 11 of the end of described resistance R 1b and the second closed loop Hall current sensor CHB-25NP joins, the other end ground connection of described resistance R 1b;

Described B phase signals amplifying circuit module is by the second operational amplifier chip OP07CP, resistance R 2b, R3b, R4b and R5b, and diode D1b and D2b form; The pin 2 of described the second operational amplifier chip OP07CP and the end of resistance R 2b, the end of resistance R 4b, the positive pole of the negative pole of diode D1b and diode D2b joins, the end of the other end of described resistance R 2b and resistance R 1b joins, the pin 3 of described the second operational amplifier chip OP07CP and the end of resistance R 3b, the negative pole of the positive pole of diode D1b and diode D2b joins, the other end ground connection of described resistance R 3b, pin 4 and the negative supply-VCC of described the second operational amplifier chip OP07CP join, pin 7 and the positive supply VCC of described the second operational amplifier chip OP07CP join, and the pin 6 of described the second operational amplifier chip OP07CP joins with the other end of resistance R 4b and the end of resistance R 5b;

Described B phase filter circuit module is by resistance R 6b, inductance L 1b, L2b, L3b, L4b, L5b, L6b and L7b, and capacitor C 1b, C2b and C3b form; The end of described inductance L 1b and the other end of resistance R 5b join, the end of the end of described inductance L 2b and the other end of inductance L 1b and inductance L 5b joins, the other end of described inductance L 5b is by capacitor C 1b ground connection, the end of the end of described inductance L 3b and the other end of inductance L 2b and inductance L 6b joins, the other end of described inductance L 6b is by capacitor C 2b ground connection, the end of the end of described inductance L 4b and the other end of inductance L 3b and inductance L 7b joins, the other end of described inductance L 7b is by capacitor C 3b ground connection, the other end of described inductance L 4b is by resistance R 6b ground connection, and the other end of described inductance L 4b is the output terminal B-OUT of described B phase filter circuit module and joins with the signal input part of data collecting card.

Above-mentioned based on fractal and power cable fault recognition system wavelet transformation, it is characterized in that: described C phase Hall current sensor is the 3rd closed loop Hall current sensor CHB-25NP, described the 3rd closed loop Hall current sensor CHB-25NP is connected on the C phase line of cable by pin 1 and pin 6, pin 2 and its pin 10 of described the 3rd closed loop Hall current sensor CHB-25NP join, pin 3 and its pin 9 of described the 3rd closed loop Hall current sensor CHB-25NP join, pin 4 and its pin 8 of described the 3rd closed loop Hall current sensor CHB-25NP join, pin 5 and its pin 7 of described the 3rd closed loop Hall current sensor CHB-25NP join, pin 12 and the positive supply VCC of described the 3rd closed loop Hall current sensor CHB-25NP join, and pin 13 and the negative supply-VCC of described the 3rd closed loop Hall current sensor CHB-25NP join;

Described C phase I/V change-over circuit module is made of resistance R 1c, and the pin 11 of the end of described resistance R 1c and the 3rd closed loop Hall current sensor CHB-25NP joins, the other end ground connection of described resistance R 1c;

Described C phase signals amplifying circuit module is by the 3rd operational amplifier chip OP07CP, resistance R 2c, R3c, R4c and R5c, and diode D1c and D2c form; The pin 2 of described the 3rd operational amplifier chip OP07CP and the end of resistance R 2c, the end of resistance R 4c, the positive pole of the negative pole of diode D1c and diode D2c joins, the end of the other end of described resistance R 2c and resistance R 1c joins, the pin 3 of described the 3rd operational amplifier chip OP07CP and the end of resistance R 3c, the negative pole of the positive pole of diode D1c and diode D2c joins, the other end ground connection of described resistance R 3c, pin 4 and the negative supply-VCC of described the 3rd operational amplifier chip OP07CP join, pin 7 and the positive supply VCC of described the 3rd operational amplifier chip OP07CP join, and the pin 6 of described the 3rd operational amplifier chip OP07CP joins with the other end of resistance R 4c and the end of resistance R 5c;

Described C phase filter circuit module is by resistance R 6c, inductance L 1c, L2c, L3c, L4c, L5c, L6c and L7c, and capacitor C 1c, C2c and C3c form; The end of described inductance L 1c and the other end of resistance R 5c join, the end of the end of described inductance L 2c and the other end of inductance L 1c and inductance L 5c joins, the other end of described inductance L 5c is by capacitor C 1c ground connection, the end of the end of described inductance L 3c and the other end of inductance L 2c and inductance L 6c joins, the other end of described inductance L 6c is by capacitor C 2c ground connection, the end of the end of described inductance L 4c and the other end of inductance L 3c and inductance L 7c joins, the other end of described inductance L 7c is by capacitor C 3c ground connection, the other end of described inductance L 4c is by resistance R 6c ground connection, and the other end of described inductance L 4c is the output terminal C-OUT of described C phase filter circuit module and joins with the signal input part of data collecting card.

Above-mentioned based on fractal and power cable fault recognition system wavelet transformation, it is characterized in that: described data collecting card is the PCI6221 data collecting card, described main control computer is the computing machine with the PCI slot, and described PCI6221 data collecting card is inserted on the described PCI slot.

The present invention also provides a kind of step simple, can identify simply, rapidly, accurately and efficiently the power cable fault recognition methods based on fractal and wavelet transformation of the type of cable short circuit fault, it is characterized in that the method may further comprise the steps:

Step 1, signal detect in real time and upload synchronously: detect in real time by the A phase current of A phase Hall current sensor to detected cable, and with the real-time A phase current signal i that detects _aSuccessively by A phase I/V change-over circuit module, A phase signals amplifying circuit module and A mutually filter circuit module carry out being uploaded to synchronously data collecting card after I/V conversion, amplification and filtering are processed; By B phase Hall current sensor the B phase current that is identified cable is detected in real time, and with the real-time B phase current signal i that detects _bSuccessively by B phase I/V change-over circuit module, B phase signals amplifying circuit module and B mutually filter circuit module carry out being uploaded to synchronously data collecting card after I/V conversion, amplification and filtering are processed; By C phase Hall current sensor the C phase current that is identified cable is detected in real time, and with the real-time C phase current signal i that detects _cSuccessively by C phase I/V change-over circuit module, C phase signals amplifying circuit module and C mutually filter circuit module carry out being uploaded to synchronously data collecting card after I/V conversion, amplification and filtering are processed;

Step 2, signals collecting and storage: data collecting card is to A phase current signal i _a, B phase current signal i _bWith C phase current signal i _cAfter gathering the also corresponding A/D of carrying out conversion, synchronous driving is to main control computer; Simultaneously, by main control computer A phase current signal i _a, B phase current signal i _bWith C phase current signal i _cSampled point quantity, all sampled points and the corresponding sampling instant of each sampled point store;

Step 3, cable fault identification: when detected cable breaks down, the A phase current signal i that data collecting card sends _a, B phase current signal i _bWith C phase current signal i _cBe fault-signal, this moment is by the A phase current signal i of main control computer to being sent by data collecting card _a, B phase current signal i _bWith C phase current signal i _cCarry out analyzing and processing, and the corresponding fault type that draws detected cable belongs to any in A phase ground short circuit fault, B phase ground short circuit fault, C phase ground short circuit fault, AB line to line fault earth fault, AB phase fault, BC line to line fault earth fault, BC phase fault, AC line to line fault earth fault, AC phase fault and the ABC three phase short circuit fault, and its analyzing and processing process is as follows:

Step 301, employing fractal method carry out cable fault just to be identified, and detailed process is:

Step 3011, current waveform figure are drawn: described main control computer calls the current waveform drafting module and draws out A phase current signal i _aA phase current waveform figure, B phase current signal i with sampling time t variation _bB phase current waveform figure and C phase current signal i with sampling time t variation _cC phase current waveform figure with sampling time t variation;

Step 3012, fractal dimension calculate: at first, suppose that the A phase current waveform is the bounded set of points F of Euclidean space _A, be ε with the length of side _ALattice cover this point set F _AThe time, suppose N _A(ε _A) for the length of side be ε _AShi Qizhong comprises point set F _AIn the non-NULL lattice number of point, described main control computer calls the fractal dimension computing module and according to formula

Calculate A phase fractal dimension D _AThen, suppose that the B phase current waveform is the bounded set of points F of Euclidean space _B, be ε with the length of side _BLattice cover this point set F _BThe time, suppose N _B(ε _B) for the length of side be ε _BShi Qizhong comprises point set F _BIn the non-NULL lattice number of point, described main control computer calls the fractal dimension computing module and according to formula

Calculate B phase fractal dimension D _BThen, suppose that the C phase current waveform is the bounded set of points F of Euclidean space _C, be ε with the length of side _CLattice cover this point set F _CThe time, suppose N _C(ε _C) for the length of side be ε _CShi Qizhong comprises point set F _CIn the non-NULL lattice number of point, described main control computer calls the fractal dimension computing module and according to formula

Calculate C phase fractal dimension D _C

Step 3013, the comparison of three-phase fractal dimension and cable fault are just identified: described main control computer is with A phase fractal dimension D _A, B phase fractal dimension D _BWith C fractal dimension D mutually _CCompare, and divide five kinds of situations that cable fault is carried out just identification according to comparison result:

Work as D _B＜D _C＜D _AThe time, being judged to be A phase ground short circuit fault, end of identification is also exported recognition result;

Work as D _A＜D _B＜D _CThe time, being judged to be C phase ground short circuit fault, end of identification is also exported recognition result;

Work as D _C＜D _A＜D _BThe time, be judged to be B phase ground short circuit fault, AB line to line fault earth fault or AB phase fault, execution in step 302;

Work as D _A＜D _C＜D _BThe time, be judged to be ABC three phase short circuit fault, BC line to line fault earth fault or BC phase fault, execution in step 302;

Work as D _B＜D _A＜D _CThe time, be judged to be AC line to line fault earth fault or AC phase fault, execution in step 302;

Step 302, described main control computer call triumphant human relations boolean conversion module with A phase current signal i _a, B phase current signal i _bWith C phase current signal i _cTransform to the modular space from phase space, obtain 0 mould current component i ₀, α mould current component i _αWith β mould current component i _β:

$i_0=\frac{1}{3}(i_a+i_b+i_c)$

$i_{\mathrm{\α}}=\frac{1}{3}(i_a-i_b)$

$i_{\mathrm{\β}}=\frac{1}{3}(i_a-i_c)$

Step 303, employing wavelet transform carry out cable fault to be identified again, and detailed process is:

Step 3031, wavelet transform and wavelet coefficient are found the solution: at first, described main control computer (4) is chosen 0 mould current component i ₀As one-dimensional signal f (n ₀) and call the wavelet transform module to one-dimensional signal f (n ₀) carry out wavelet transform, corresponding each layer wavelet coefficient of trying to achieve behind the wavelet transform, the described wavelet coefficient of each layer comprises each layer approximation coefficient and each layer detail coefficients, wherein the described detail coefficients of each layer is denoted as d _{J, k}, wherein, n ₀=0,1,2 ... N-1 and N are one-dimensional signal f (n ₀) sample sequence in sampled point quantity, one-dimensional signal f (n ₀) sample sequence in sampled point quantity, all sample sequence points and each sample sequence put corresponding sampling instant all with step 2 in the A phase current signal i that stores of main control computer (4) _a, B phase current signal i _bWith C phase current signal i _cSampled point quantity, all sampled points and the corresponding sampling instant of each sampled point corresponding one by one; J=1,2 ..., J and J are the number of plies of wavelet transform, k=0,1,2 ..., N-1 and k are one-dimensional signal f (n ₀) sample sequence in the sequence number of N sample sequence point; Then, described main control computer (4) is chosen α mould current component i _αAs one-dimensional signal f (n _α) and call the wavelet transform module to one-dimensional signal f (n _α) carry out wavelet transform, corresponding each layer wavelet coefficient of trying to achieve behind the wavelet transform, the described wavelet coefficient of each layer comprises each layer approximation coefficient and each layer detail coefficients, wherein the described detail coefficients of each layer is denoted as d' _{J, k}, wherein, n _α=0,1,2 ... N-1 and N are one-dimensional signal f (n _α) sample sequence in sampled point quantity, one-dimensional signal f (n _α) sample sequence in sampled point quantity, all sample sequence points and each sample sequence put corresponding sampling instant all with step 2 in the A phase current signal i that stores of main control computer (4) _a, B phase current signal i _bWith C phase current signal i _cSampled point quantity, all sampled points and the corresponding sampling instant of each sampled point corresponding one by one; J=1,2 ..., J and J are the number of plies of wavelet transform, k=0,1,2 ..., N-1 and k are one-dimensional signal f (n _α) sample sequence in the sequence number of N sample sequence point; Then, described main control computer (4) is chosen β mould current component i _βAs one-dimensional signal f (n _β) and call the wavelet transform module to one-dimensional signal f (n _β) carry out wavelet transform, corresponding each layer wavelet coefficient of trying to achieve behind the wavelet transform, the described wavelet coefficient of each layer comprises each layer approximation coefficient and each layer detail coefficients, wherein the described detail coefficients of each layer is denoted as d'' _{J, k}, wherein, n _β=0,1,2 ... N-1 and N are one-dimensional signal f (n _β) sample sequence in sampled point quantity, one-dimensional signal f (n _β) sample sequence in sampled point quantity, all sample sequence points and each sample sequence put corresponding sampling instant all with step 2 in the A phase current signal i that stores of main control computer (4) _a, B phase current signal i _bWith C phase current signal i _cSampled point quantity, all sampled points and the corresponding sampling instant of each sampled point corresponding one by one; J=1,2 ..., J and J are the number of plies of wavelet transform, k=0,1,2 ..., N-1 and k are one-dimensional signal f (n _β) sample sequence in the sequence number of N sample sequence point;

Step 3032, modulus maximum point detect: at first, and according to one-dimensional signal f (n ₀) the sampling order of sample sequence, from front to back to J layer detail coefficients d _{J, k}The modulus maximum point detect and record, and detect and to draw when k=i d _{J, k}Obtain the modulus maximum point, i.e. 0 mould current component i ₀Initial row mode maximum value I ₀=d _{J, i}Then, according to one-dimensional signal f (n _α) the sampling order of sample sequence, from front to back to J layer detail coefficients d' _{J, k}The modulus maximum point detect and record, and detect and to draw when k=i d' _{J, k}Obtain the modulus maximum point, i.e. α mould current component i _αInitial row mode maximum value I _α=d' _{J, i}Then, according to one-dimensional signal f (n _β) the sampling order of sample sequence, from front to back to J layer detail coefficients d'' _{J, k}The modulus maximum point detect and record, and detect and to draw when k=i d'' _{J, k}Obtain the modulus maximum point, i.e. β mould current component i _βInitial row mode maximum value I _β=d'' _{J, i}Wherein, i=0,1,2 ..., N-1;

Step 3033, the comparison of three initial row mode maximum value and cable fault are identified again: described main control computer divides D _C＜D _A＜D _B, D _A＜D _C＜D _BAnd D _B＜D _A＜D _CThree kinds of situations are with 0 mould current component i ₀Initial row mode maximum value I ₀, α mould current component i _αInitial row mode maximum value I _αWith β mould current component i _βInitial row mode maximum value I _βCompare, and according to comparison result cable fault identified again, be specially:

Work as D _C＜D _A＜D _BThe time, at first judged whether I ₀=0, work as I ₀, judged whether I at=0 o'clock _α=2I _β, work as I ₀=0 and I _α=2I _βThe time, be judged as the AB phase fault; Work as I ₀, at first judged whether I at ≠ 0 o'clock _β=0 and | I ₀|=| I _α|, work as I ₀≠ 0, I _β=0 and | I ₀|=| I _α| the time, be judged as B phase ground short circuit fault; Then judged whether I ₀=2I _β-I _α, work as I ₀≠ 0 and I ₀=2I _β-I _αThe time, be judged as AB line to line fault earth fault; End of identification is also exported recognition result;

Work as D _A＜D _C＜D _BThe time, at first judged whether I ₀=0, work as I ₀, judged whether I at=0 o'clock _α=-I _β, work as I ₀=0 and I _α=-I _βThe time, be judged as the BC phase fault; Work as I ₀, judged whether I at ≠ 0 o'clock ₀=-I _α-I _β, work as I ₀≠ 0 and I ₀=-I _α-I _βThe time, be judged as BC line to line fault earth fault; Work as I ₀≠ 0 and I ₀≠-I _α-I _βThe time, be judged as the ABC three phase short circuit fault; End of identification is also exported recognition result;

Work as D _B＜D _A＜D _CThe time, at first judged whether I ₀=0, work as I ₀, work as I at=0 o'clock ₀=0 o'clock, judged whether Work as I ₀=0 and

The time, be judged as the AC phase fault; Work as I ₀, judged whether I at ≠ 0 o'clock ₀=2I _α-I _β, work as I ₀≠ 0 and I ₀=2I _α-I _βThe time, be judged as AC line to line fault earth fault; End of identification is also exported recognition result.

Above-mentioned method is characterized in that: ε described in the step 3012 _A, ε _BAnd ε _CValue equate.

Above-mentioned method is characterized in that: the value of J described in the step 3031 and 3032 is 3.

The present invention compared with prior art has the following advantages:

1, the present invention is based on the circuit structure of power cable fault recognition system of fractal and wavelet transformation simple, rationally novel in design, it is convenient to realize.

2, the present invention adopts Hall current sensor that cable current is detected, can measure the AC signal of the various shapes from direct current to KHz up to a hundred, therefore measure bandwidth, and can be with the little current signal that changes secondary side into of the large current signal waveform loyalty of cable, and on physical connection, electric primary side and measurement secondary side have been carried out effective electrical isolation, reached signal on former limit, undistorted transmission between the secondary, parameter by circuit component reasonable in design, satisfied the requirement of the input range of data collecting card, simultaneously cable current fault transient travelling wave signal had good measurement of inductance ability, have the undistorted of good propagation function and signal for the high frequency transient travelling wave signal of measuring in the fault transient process, compared with traditional current transformer, the cable fault current signal there is trickleer transmission and better stable, for the data analysis of main control computer provides good hardware supported, overcome the available technology adopting current transformer and carried out cable current to detect the survey frequency that exists limited, all there are larger error in no-load voltage ratio and phase measurement, defective and the deficiencies such as circuit complexity.

3, the present invention is based on stability and the reliability of power cable fault recognition system of fractal and wavelet transformation high so that system can be continuously, reliably the cable current signal is gathered and stores.

4, the power cable fault recognition methods that the present invention is based on fractal and wavelet transformation combines fractal method with wavelet analysis method, can directly judge mutually ground short circuit fault of A phase ground short circuit fault and C by fractal method, and all the other 8 kinds of short troubles are divided three classes, can judge all the other 8 kinds of short troubles in conjunction with wavelet analysis method again, improve the efficient of cable fault identification, and can identify simply, rapidly, accurately and efficiently the type of cable short circuit fault.

5, of the present invention practical, result of use is good, is convenient to promote the use of.

In sum, the present invention is novel in design rationally, and the precision that cable current is detected is high, stability and reliability are high, can identify simply, rapidly, accurately and efficiently the type of cable short circuit fault, and practical, result of use is good, is convenient to promote the use of.

Below by drawings and Examples, technical scheme of the present invention is described in further detail.

Description of drawings

Fig. 1 is the schematic block circuit diagram that the present invention is based on the power cable fault recognition system of fractal and wavelet transformation.

Fig. 2 is the mutually circuit theory diagrams of filter circuit module of A phase Hall current sensor of the present invention, A phase I/V change-over circuit module, A phase signals amplifying circuit module and A.

Fig. 3 is the mutually circuit theory diagrams of filter circuit module of B phase Hall current sensor of the present invention, B phase I/V change-over circuit module, B phase signals amplifying circuit module and B.

Fig. 4 is the mutually circuit theory diagrams of filter circuit module of C phase Hall current sensor of the present invention, C phase I/V change-over circuit module, C phase signals amplifying circuit module and C.

Fig. 5 is the method flow diagram that the present invention is based on the power cable fault recognition methods of fractal and wavelet transformation.

Description of reference numerals:

1-current detection circuit module; 1-1-A phase Hall current sensor;

1-2-B phase Hall current sensor; 1-3-C phase Hall current sensor;

2-signal conditioning circuit module; 2-1-A phase current signal conditioning circuit module;

2-11-A phase I/V change-over circuit module; 2-12-A phase signals amplifying circuit module;

2-13-A phase filter circuit module; 2-2-B phase current signal conditioning circuit module;

2-21-B phase I/V change-over circuit module; 2-22-B phase signals amplifying circuit module;

2-23-B phase filter circuit module; 2-3-C phase current signal conditioning circuit module;

2-31-C phase I/V change-over circuit module; 2-32-C phase signals amplifying circuit module;

2-33-C phase filter circuit module; 3-data collecting card;

4-main control computer.

Embodiment

As shown in Figure 1, of the present invention based on fractal and power cable fault recognition system wavelet transformation, comprise the current detection circuit module 1 of joining successively, signal conditioning circuit module 2, data collecting card 3 and main control computer 4, described current detection circuit module 1 comprises the A phase Hall current sensor 1-1 that detects in real time for the A phase current to threephase cable, be used for the B phase Hall current sensor 1-2 that the B phase current to threephase cable detects in real time and be used for mutually Hall current sensor 1-3 of C that the C phase current to threephase cable detects in real time, described signal conditioning circuit module 2 comprises the A phase current signal conditioning circuit module 2-1 that nurses one's health for to the signal of A phase Hall current sensor 1-1 output, be used for B phase current signal conditioning circuit module 2-2 that the signal of B phase Hall current sensor 1-2 output is nursed one's health and be used for the C phase current signal conditioning circuit module 2-3 that nurses one's health of the signal of Hall current sensor 1-3 output mutually to C, described A phase current signal conditioning circuit module 2-1 is by the A phase I/V change-over circuit module 2-11 that joins successively, A phase signals amplifying circuit module 2-12 and A mutually filter circuit module 2-13 consist of, described B phase current signal conditioning circuit module 2-2 is by the B phase I/V change-over circuit module 2-21 that joins successively, B phase signals amplifying circuit module 2-22 and B mutually filter circuit module 2-23 consist of, and described C phase current signal conditioning circuit module 2-3 is by the C phase I/V change-over circuit module 2-31 that joins successively, C phase signals amplifying circuit module 2-32 and C mutually filter circuit module 2-33 consist of.

As shown in Figure 2, in the present embodiment, described A phase Hall current sensor 1-1 is the first closed loop Hall current sensor CHB-25NP, described the first closed loop Hall current sensor CHB-25NP is connected on the A phase line of cable by pin 1 and pin 6, pin 2 and its pin 10 of described the first closed loop Hall current sensor CHB-25NP join, pin 3 and its pin 9 of described the first closed loop Hall current sensor CHB-25NP join, pin 4 and its pin 8 of described the first closed loop Hall current sensor CHB-25NP join, pin 5 and its pin 7 of described the first closed loop Hall current sensor CHB-25NP join, pin 12 and the positive supply VCC of described the first closed loop Hall current sensor CHB-25NP join, and pin 13 and the negative supply-VCC of described the first closed loop Hall current sensor CHB-25NP join;

Described A phase I/V change-over circuit module 2-11 is made of resistance R 1a, and the pin 11 of the end of described resistance R 1a and the first closed loop Hall current sensor CHB-25NP joins, the other end ground connection of described resistance R 1a;

Described A phase signals amplifying circuit module 2-12 is by the first operational amplifier chip OP07CP, resistance R 2a, R3a, R4a and R5a, and diode D1a and D2a form; The pin 2 of described the first operational amplifier chip OP07CP and the end of resistance R 2a, the end of resistance R 4a, the positive pole of the negative pole of diode D1a and diode D2a joins, the end of the other end of described resistance R 2a and resistance R 1a joins, the pin 3 of described the first operational amplifier chip OP07CP and the end of resistance R 3a, the negative pole of the positive pole of diode D1a and diode D2a joins, the other end ground connection of described resistance R 3a, pin 4 and the negative supply-VCC of described the first operational amplifier chip OP07CP join, pin 7 and the positive supply VCC of described the first operational amplifier chip OP07CP join, and the pin 6 of described the first operational amplifier chip OP07CP joins with the other end of resistance R 4a and the end of resistance R 5a;

Described A phase filter circuit module 2-13 is by resistance R 6a, inductance L 1a, L2a, L3a, L4a, L5a, L6a and L7a, and capacitor C 1a, C2a and C3a form; The end of described inductance L 1a and the other end of resistance R 5a join, the end of the end of described inductance L 2a and the other end of inductance L 1a and inductance L 5a joins, the other end of described inductance L 5a is by capacitor C 1a ground connection, the end of the end of described inductance L 3a and the other end of inductance L 2a and inductance L 6a joins, the other end of described inductance L 6a is by capacitor C 2a ground connection, the end of the end of described inductance L 4a and the other end of inductance L 3a and inductance L 7a joins, the other end of described inductance L 7a is by capacitor C 3a ground connection, the other end of described inductance L 4a is by resistance R 6a ground connection, and the other end of described inductance L 4a is output terminals A-OUT of described A phase filter circuit module 2-13 and joins with the signal input part of data collecting card 3.A phase filter circuit module 2-13 is 7 rank filtering circuits, passband is DC-200kHz, has substantially kept the following signal of 200kHz, and 200kHz is above thinks interference noise and with its filtering.

When cable A phase current passes through the primary side of A phase Hall current sensor 1-1, the secondary side output terminal of A phase Hall current sensor 1-1 will induce and the little electric current of the synchronous output of primary side current same frequency, its waveform fully and primary side be consistent, this weak current flows through the resistance R 1a among the A phase I/V change-over circuit module 2-11 afterwards, be converted to a faint interchange small voltage, then amplify by A phase signals amplifying circuit module 2-12 and preliminary filtering, its output signal enters A phase filter circuit module 2-13 again and carries out exporting after the filtering.Among the A phase signals amplifying circuit module 2-12; the diode D1a of two reversal connections of the first operational amplifier chip OP07CP input end and D2a are the input ends of protecting the first operational amplifier chip OP07CP; namely when the added overtension of input end, can damage the transistor of input stage; diode D1a and the D2a of two reverse parallel connections of access just can be limited in input voltage below the forward voltage drop of diode.

As shown in Figure 3, in the present embodiment, described B phase Hall current sensor 1-2 is the second closed loop Hall current sensor CHB-25NP, described the second closed loop Hall current sensor CHB-25NP is connected on the B phase line of cable by pin 1 and pin 6, pin 2 and its pin 10 of described the second closed loop Hall current sensor CHB-25NP join, pin 3 and its pin 9 of described the second closed loop Hall current sensor CHB-25NP join, pin 4 and its pin 8 of described the second closed loop Hall current sensor CHB-25NP join, pin 5 and its pin 7 of described the second closed loop Hall current sensor CHB-25NP join, pin 12 and the positive supply VCC of described the second closed loop Hall current sensor CHB-25NP join, and pin 13 and the negative supply-VCC of described the second closed loop Hall current sensor CHB-25NP join;

Described B phase I/V change-over circuit module 2-21 is made of resistance R 1b, and the pin 11 of the end of described resistance R 1b and the second closed loop Hall current sensor CHB-25NP joins, the other end ground connection of described resistance R 1b;

Described B phase signals amplifying circuit module 2-22 is by the second operational amplifier chip OP07CP, resistance R 2b, R3b, R4b and R5b, and diode D1b and D2b form; The pin 2 of described the second operational amplifier chip OP07CP and the end of resistance R 2b, the end of resistance R 4b, the positive pole of the negative pole of diode D1b and diode D2b joins, the end of the other end of described resistance R 2b and resistance R 1b joins, the pin 3 of described the second operational amplifier chip OP07CP and the end of resistance R 3b, the negative pole of the positive pole of diode D1b and diode D2b joins, the other end ground connection of described resistance R 3b, pin 4 and the negative supply-VCC of described the second operational amplifier chip OP07CP join, pin 7 and the positive supply VCC of described the second operational amplifier chip OP07CP join, and the pin 6 of described the second operational amplifier chip OP07CP joins with the other end of resistance R 4b and the end of resistance R 5b;

Described B phase filter circuit module 2-23 is by resistance R 6b, inductance L 1b, L2b, L3b, L4b, L5b, L6b and L7b, and capacitor C 1b, C2b and C3b form; The end of described inductance L 1b and the other end of resistance R 5b join, the end of the end of described inductance L 2b and the other end of inductance L 1b and inductance L 5b joins, the other end of described inductance L 5b is by capacitor C 1b ground connection, the end of the end of described inductance L 3b and the other end of inductance L 2b and inductance L 6b joins, the other end of described inductance L 6b is by capacitor C 2b ground connection, the end of the end of described inductance L 4b and the other end of inductance L 3b and inductance L 7b joins, the other end of described inductance L 7b is by capacitor C 3b ground connection, the other end of described inductance L 4b is by resistance R 6b ground connection, and the other end of described inductance L 4b is the output terminal B-OUT of described B phase filter circuit module 2-23 and joins with the signal input part of data collecting card 3.B phase filter circuit module 2-23 is 7 rank filtering circuits, passband is DC-200kHz, has substantially kept the following signal of 200kHz, and 200kHz is above thinks interference noise and with its filtering.

When cable B phase current passes through the primary side of B phase Hall current sensor 1-2, the secondary side output terminal of B phase Hall current sensor 1-2 will induce and the little electric current of the synchronous output of primary side current same frequency, its waveform fully and primary side be consistent, this weak current flows through the resistance R 1b among the B phase I/V change-over circuit module 2-21 afterwards, be converted to a faint interchange small voltage, then amplify by B phase signals amplifying circuit module 2-22 and preliminary filtering, its output signal enters B phase filter circuit module 2-23 again and carries out exporting after the filtering.Among the B phase signals amplifying circuit module 2-22; the diode D1b of two reversal connections of the second operational amplifier chip OP07CP input end and D2b are the input ends of protecting the second operational amplifier chip OP07CP; namely when the added overtension of input end, can damage the transistor of input stage; diode D1b and the D2b of two reverse parallel connections of access just can be limited in input voltage below the forward voltage drop of diode.

As shown in Figure 4, in the present embodiment, described C phase Hall current sensor 1-3 is the 3rd closed loop Hall current sensor CHB-25NP, described the 3rd closed loop Hall current sensor CHB-25NP is connected on the C phase line of cable by pin 1 and pin 6, pin 2 and its pin 10 of described the 3rd closed loop Hall current sensor CHB-25NP join, pin 3 and its pin 9 of described the 3rd closed loop Hall current sensor CHB-25NP join, pin 4 and its pin 8 of described the 3rd closed loop Hall current sensor CHB-25NP join, pin 5 and its pin 7 of described the 3rd closed loop Hall current sensor CHB-25NP join, pin 12 and the positive supply VCC of described the 3rd closed loop Hall current sensor CHB-25NP join, and pin 13 and the negative supply-VCC of described the 3rd closed loop Hall current sensor CHB-25NP join;

Described C phase I/V change-over circuit module 2-31 is made of resistance R 1c, and the pin 11 of the end of described resistance R 1c and the 3rd closed loop Hall current sensor CHB-25NP joins, the other end ground connection of described resistance R 1c;

Described C phase signals amplifying circuit module 2-32 is by the 3rd operational amplifier chip OP07CP, resistance R 2c, R3c, R4c and R5c, and diode D1c and D2c form; The pin 2 of described the 3rd operational amplifier chip OP07CP and the end of resistance R 2c, the end of resistance R 4c, the positive pole of the negative pole of diode D1c and diode D2c joins, the end of the other end of described resistance R 2c and resistance R 1c joins, the pin 3 of described the 3rd operational amplifier chip OP07CP and the end of resistance R 3c, the negative pole of the positive pole of diode D1c and diode D2c joins, the other end ground connection of described resistance R 3c, pin 4 and the negative supply-VCC of described the 3rd operational amplifier chip OP07CP join, pin 7 and the positive supply VCC of described the 3rd operational amplifier chip OP07CP join, and the pin 6 of described the 3rd operational amplifier chip OP07CP joins with the other end of resistance R 4c and the end of resistance R 5c;

Described C phase filter circuit module 2-33 is by resistance R 6c, inductance L 1c, L2c, L3c, L4c, L5c, L6c and L7c, and capacitor C 1c, C2c and C3c form; The end of described inductance L 1c and the other end of resistance R 5c join, the end of the end of described inductance L 2c and the other end of inductance L 1c and inductance L 5c joins, the other end of described inductance L 5c is by capacitor C 1c ground connection, the end of the end of described inductance L 3c and the other end of inductance L 2c and inductance L 6c joins, the other end of described inductance L 6c is by capacitor C 2c ground connection, the end of the end of described inductance L 4c and the other end of inductance L 3c and inductance L 7c joins, the other end of described inductance L 7c is by capacitor C 3c ground connection, the other end of described inductance L 4c is by resistance R 6c ground connection, and the other end of described inductance L 4c is the output terminal C-OUT of described C phase filter circuit module 2-33 and joins with the signal input part of data collecting card 3.C phase filter circuit module 2-33 is 7 rank filtering circuits, passband is DC-200kHz, has substantially kept the following signal of 200kHz, and 200kHz is above thinks interference noise and with its filtering.

When cable C phase current passes through the primary side of C phase Hall current sensor 1-3, the secondary side output terminal of C phase Hall current sensor 1-3 will induce and the little electric current of the synchronous output of primary side current same frequency, its waveform fully and primary side be consistent, this weak current flows through the resistance R 1C among the C phase I/V change-over circuit module 2-31 afterwards, be converted to a faint interchange small voltage, then amplify by C phase signals amplifying circuit module 2-32 and preliminary filtering, its output signal enters C phase filter circuit module 2-33 again and carries out exporting after the filtering.Among the C phase signals amplifying circuit module 2-32; the diode D1c of two reversal connections of the 3rd operational amplifier chip OP07CP input end and D2c are the input ends of protecting the 3rd operational amplifier chip OP07CP; namely when the added overtension of input end, can damage the transistor of input stage; diode D1c and the D2c of two reverse parallel connections of access just can be limited in input voltage below the forward voltage drop of diode.

In the present embodiment, described data collecting card 3 is the PCI6221 data collecting card, and described main control computer 4 is the computing machine with the PCI slot, and described PCI6221 data collecting card is inserted on the described PCI slot.

As shown in Figure 5, of the present invention based on fractal and power cable fault recognition methods wavelet transformation, may further comprise the steps:

Step 1, signal detect in real time and upload synchronously: by A phase Hall current sensor 1-1 the A phase current of detected cable detected in real time, and with the real-time A phase current signal i that detects _aSuccessively by A phase I/V change-over circuit module 2-11, A phase signals amplifying circuit module 2-12 and A mutually filter circuit module 2-13 carry out being uploaded to synchronously data collecting card 3 after I/V conversion, amplification and filtering are processed; 1-2 detects in real time to the B phase current that is identified cable by B phase Hall current sensor, and with the real-time B phase current signal i that detects _bSuccessively by B phase I/V change-over circuit module 2-21, B phase signals amplifying circuit module 2-22 and B mutually filter circuit module 2-23 carry out being uploaded to synchronously data collecting card 3 after I/V conversion, amplification and filtering are processed; 1-3 detects in real time to the C phase current that is identified cable by C phase Hall current sensor, and with the real-time C phase current signal i that detects _cSuccessively by C phase I/V change-over circuit module 2-31, C phase signals amplifying circuit module 2-32 and C mutually filter circuit module 2-33 carry out being uploaded to synchronously data collecting card 3 after I/V conversion, amplification and filtering are processed;

Step 2, signals collecting and storage: 3 pairs of A phase current signals of data collecting card i _a, B phase current signal i _bWith C phase current signal i _cAfter gathering the also corresponding A/D of carrying out conversion, synchronous driving is to main control computer 4; Simultaneously, by main control computer 4A phase current signal i _a, B phase current signal i _bWith C phase current signal i _cSampled point quantity, all sampled points and the corresponding sampling instant of each sampled point store;

Step 3, cable fault identification: when detected cable breaks down, the A phase current signal i that data collecting card 3 sends _a, B phase current signal i _bWith C phase current signal i _cBe fault-signal, this moment is by 4 couples of A phase current signal i that sent by data collecting card 3 of main control computer _a, B phase current signal i _bWith C phase current signal i _cCarry out analyzing and processing, and the corresponding fault type that draws detected cable belongs to any in A phase ground short circuit fault, B phase ground short circuit fault, C phase ground short circuit fault, AB line to line fault earth fault, AB phase fault, BC line to line fault earth fault, BC phase fault, AC line to line fault earth fault, AC phase fault and the ABC three phase short circuit fault, and its analyzing and processing process is as follows:

Step 301, employing fractal method carry out cable fault just to be identified, and detailed process is:

Step 3011, current waveform figure are drawn: described main control computer 4 calls the current waveform drafting module and draws out A phase current signal i _aA phase current waveform figure, B phase current signal i with sampling time t variation _bB phase current waveform figure and C phase current signal i with sampling time t variation _cC phase current waveform figure with sampling time t variation;

Step 3012, fractal dimension calculate: at first, suppose that the A phase current waveform is the bounded set of points F of Euclidean space _A, be ε with the length of side _ALattice cover this point set F _AThe time, suppose N _A(ε _A) for the length of side be ε _AShi Qizhong comprises point set F _AIn the non-NULL lattice number of point, described main control computer 4 calls the fractal dimension computing module and according to formula Calculate A phase fractal dimension D _AThen, suppose that the B phase current waveform is the bounded set of points F of Euclidean space _B, be ε with the length of side _BLattice cover this point set F _BThe time, suppose N _B(ε _B) for the length of side be ε _BShi Qizhong comprises point set F _BIn the non-NULL lattice number of point, described main control computer 4 calls the fractal dimension computing module and according to formula

Calculate B phase fractal dimension D _BThen, suppose that the C phase current waveform is the bounded set of points F of Euclidean space _C, be ε with the length of side _CLattice cover this point set F _CThe time, suppose N _C(ε _C) for the length of side be ε _CShi Qizhong comprises point set F _CIn the non-NULL lattice number of point, described main control computer 4 calls the fractal dimension computing module and according to formula Calculate C phase fractal dimension D _C

Step 3013, the comparison of three-phase fractal dimension and cable fault are just identified: described main control computer 4 is with A phase fractal dimension D _A, B phase fractal dimension D _BWith C fractal dimension D mutually _CCompare, and divide five kinds of situations that cable fault is carried out just identification according to comparison result:

Work as D _B＜D _C＜D _AThe time, being judged to be A phase ground short circuit fault, end of identification is also exported recognition result;

Work as D _A＜D _B＜D _CThe time, being judged to be C phase ground short circuit fault, end of identification is also exported recognition result;

Work as D _C＜D _A＜D _BThe time, be judged to be B phase ground short circuit fault, AB line to line fault earth fault or AB phase fault, execution in step 302;

Work as D _A＜D _C＜D _BThe time, be judged to be ABC three phase short circuit fault, BC line to line fault earth fault or BC phase fault, execution in step 302;

Work as D _B＜D _A＜D _CThe time, be judged to be AC line to line fault earth fault or AC phase fault, execution in step 302;

Step 302, described main control computer 4 call triumphant human relations boolean conversion module with A phase current signal i _a, B phase current signal i _bWith C phase current signal i _cTransform to the modular space from phase space, obtain 0 mould current component i ₀, α mould current component i _αWith β mould current component i _β:

$i_0=\frac{1}{3}(i_a+i_b+i_c)$

$i_{\mathrm{\α}}=\frac{1}{3}(i_a-i_b)$

$i_{\mathrm{\β}}=\frac{1}{3}(i_a-i_c)$

Described main control computer 4 calls triumphant human relations boolean conversion module when carrying out triumphant human relations boolean conversion, is according to formula i=S * i _pCarry out conversion, wherein, i is the A phase current signal i of phase space _a, B phase current signal i _bWith C phase current signal i _cVector, i _p0 mould current component i for the modular space ₀, α mould current component i _αWith β mould current component i _βVector, $S=\left[\begin{array}{ccc}1& 1& 1\\ 1& -2& 1\\ 1& 1& -2\end{array}\right];$

Step 303, employing wavelet transform carry out cable fault to be identified again, and detailed process is:

Step 3031, wavelet transform and wavelet coefficient are found the solution: at first, described main control computer (4) is chosen 0 mould current component i ₀As one-dimensional signal f (n ₀) and call the wavelet transform module to one-dimensional signal f (n ₀) carry out wavelet transform, corresponding each layer wavelet coefficient of trying to achieve behind the wavelet transform, the described wavelet coefficient of each layer comprises each layer approximation coefficient and each layer detail coefficients, wherein the described detail coefficients of each layer is denoted as d _{J, k}, wherein, n ₀=0,1,2 ... N-1 and N are one-dimensional signal f (n ₀) sample sequence in sampled point quantity, one-dimensional signal f (n ₀) sample sequence in sampled point quantity, all sample sequence points and each sample sequence put corresponding sampling instant all with step 2 in the A phase current signal i that stores of main control computer (4) _a, B phase current signal i _bWith C phase current signal i _cSampled point quantity, all sampled points and the corresponding sampling instant of each sampled point corresponding one by one; J=1,2 ..., J and J are the number of plies of wavelet transform, k=0,1,2 ..., N-1 and k are one-dimensional signal f (n ₀) sample sequence in the sequence number of N sample sequence point; Then, described main control computer (4) is chosen α mould current component i _αAs one-dimensional signal f (n _α) and call the wavelet transform module to one-dimensional signal f (n _α) carry out wavelet transform, corresponding each layer wavelet coefficient of trying to achieve behind the wavelet transform, the described wavelet coefficient of each layer comprises each layer approximation coefficient and each layer detail coefficients, wherein the described detail coefficients of each layer is denoted as d' _{J, k}, wherein, n _α=0,1,2 ... N-1 and N are one-dimensional signal f (n _α) sample sequence in sampled point quantity, one-dimensional signal f (n _α) sample sequence in sampled point quantity, all sample sequence points and each sample sequence put corresponding sampling instant all with step 2 in the A phase current signal i that stores of main control computer (4) _a, B phase current signal i _bWith C phase current signal i _cSampled point quantity, all sampled points and the corresponding sampling instant of each sampled point corresponding one by one; J=1,2 ..., J and J are the number of plies of wavelet transform, k=0,1,2 ..., N-1 and k are one-dimensional signal f (n _α) sample sequence in the sequence number of N sample sequence point; Then, described main control computer (4) is chosen β mould current component i _βAs one-dimensional signal f (n _β) and call the wavelet transform module to one-dimensional signal f (n _β) carry out wavelet transform, corresponding each layer wavelet coefficient of trying to achieve behind the wavelet transform, the described wavelet coefficient of each layer comprises each layer approximation coefficient and each layer detail coefficients, wherein the described detail coefficients of each layer is denoted as d'' _{J, k}, wherein, n _β=0,1,2 ... N-1 and N are one-dimensional signal f (n _β) sample sequence in sampled point quantity, one-dimensional signal f (n _β) sample sequence in sampled point quantity, all sample sequence points and each sample sequence put corresponding sampling instant all with step 2 in the A phase current signal i that stores of main control computer (4) _a, B phase current signal i _bWith C phase current signal i _cSampled point quantity, all sampled points and the corresponding sampling instant of each sampled point corresponding one by one; J=1,2 ..., J and J are the number of plies of wavelet transform, k=0,1,2 ..., N-1 and k are one-dimensional signal f (n _β) sample sequence in the sequence number of N sample sequence point;

Step 3032, modulus maximum point detect: at first, and according to one-dimensional signal f (n ₀) the sampling order of sample sequence, from front to back to J layer detail coefficients d _{J, k}The modulus maximum point detect and record, and detect and to draw when k=i d _{J, k}Obtain the modulus maximum point, i.e. 0 mould current component i ₀Initial row mode maximum value I ₀=d _{J, i}Then, according to one-dimensional signal f (n _α) the sampling order of sample sequence, from front to back to J layer detail coefficients d' _{J, k}The modulus maximum point detect and record, and detect and to draw when k=i d' _{J, k}Obtain the modulus maximum point, i.e. α mould current component i _αInitial row mode maximum value I _α=d' _{J, i}Then, according to one-dimensional signal f (n _β) the sampling order of sample sequence, from front to back to J layer detail coefficients d'' _{J, k}The modulus maximum point detect and record, and detect and to draw when k=i d'' _{J, k}Obtain the modulus maximum point, i.e. β mould current component i _βInitial row mode maximum value I _β=d'' _{J, i}Wherein, i=0,1,2 ..., N-1;

Step 3033, the comparison of three initial row mode maximum value and cable fault are identified again: 4 minutes D of described main control computer _C＜D _A＜D _B, D _A＜D _C＜D _BAnd D _B＜D _A＜D _CThree kinds of situations are with 0 mould current component i ₀Initial row mode maximum value I ₀, α mould current component i _αInitial row mode maximum value I _αWith β mould current component i _βInitial row mode maximum value I _βCompare, and according to comparison result cable fault identified again, be specially:

Work as D _C＜D _A＜D _BThe time, at first judged whether I ₀=0, work as I ₀, judged whether I at=0 o'clock _α=2I _β, work as I ₀=0 and I _α=2I _βThe time, be judged as the AB phase fault; Work as I ₀, at first judged whether I at ≠ 0 o'clock _β=0 and | I ₀|=| I _α|, work as I ₀≠ 0, I _β=0 and | I ₀|=| I _α| the time, be judged as B phase ground short circuit fault; Then judged whether I ₀=2I _β-I _α, work as I ₀≠ 0 and I ₀=2I _β-I _αThe time, be judged as AB line to line fault earth fault; End of identification is also exported recognition result;

Work as D _A＜D _C＜D _BThe time, at first judged whether I ₀=0, work as I ₀, judged whether I at=0 o'clock _α=-I _β, work as I ₀=0 and I _α=-I _βThe time, be judged as the BC phase fault; Work as I ₀, judged whether I at ≠ 0 o'clock ₀=-I _α-I _β, work as I ₀≠ 0 and I ₀=-I _α-I _βThe time, be judged as BC line to line fault earth fault; Work as I ₀≠ 0 and I ₀≠-I _α-I _βThe time, be judged as the ABC three phase short circuit fault; End of identification is also exported recognition result;

Work as D _B＜D _A＜D _CThe time, at first judged whether I ₀=0, work as I ₀, work as I at=0 o'clock ₀=0 o'clock, judged whether

Work as I ₀=0 and

The time, be judged as the AC phase fault; Work as I ₀, judged whether I at ≠ 0 o'clock ₀=2I _α-I _β, work as I ₀≠ 0 and I ₀=2I _α-I _βThe time, be judged as AC line to line fault earth fault; End of identification is also exported recognition result.

In the present embodiment, ε described in the step 3012 _A, ε _BAnd ε _CValue equate.The value of J described in the step 3031 and 3032 is 3, namely in the step 3031 is to have carried out 3 layer scattering wavelet transformations.

In order to verify technique effect of the present invention, detected cable has been carried out short-circuit fault simulation in A phase ground short circuit fault, B phase ground short circuit fault, C phase ground short circuit fault, AB line to line fault earth fault, AB phase fault, BC line to line fault earth fault, BC phase fault, AC line to line fault earth fault, AC phase fault and the ABC three phase short circuit fault 10, carry out successively step 1 of the present invention and step 2, and in main control computer 4, adopt MATLAB software that step 301 has been carried out emulation, the simulation result that obtains is as shown in table 1:

Table 1 fractal method carries out cable fault and just identifies simulation result

Simulation result from table 1 can be found out, various short troubles, A phase fractal dimension D _A, B phase fractal dimension D _BWith C fractal dimension D mutually _CSize cases as follows:

When A phase ground short circuit fault occurs when, D _B＜D _C＜D _A

When B phase ground short circuit fault, AB line to line fault earth fault or AB phase fault occur when, D _C＜D _A＜D _B

When C phase ground short circuit fault occurs when, D _A＜D _B＜D _C

When ABC three phase short circuit fault, BC line to line fault earth fault or BC phase fault occur when, D _A＜D _C＜D _B

When AC line to line fault earth fault or AC line to line fault earth fault occur when, D _B＜D _A＜D _C

Be consistent with the cable fault recognition methods in the step 3013.

In addition, also adopt MATLAB software that step 302 and step 303 have been carried out emulation in main control computer 4, the simulation result that obtains is as shown in table 2:

Table 2 wavelet transform carries out cable fault and identifies simulation result again

Simulation result from table 2 can be found out, various short troubles, 0 mould current component i ₀Initial row mode maximum value I ₀, α mould current component i _αInitial row mode maximum value I _αWith β mould current component i _βInitial row mode maximum value I _βSize cases as follows:

When B phase ground short circuit fault occurs when, I ₀≠ 0, I _β≈ 0 and | I ₀| ≈ | I _α|;

When AB line to line fault earth fault occurs when, I ₀≠ 0 and I ₀≈ 2I _β-I _α

When the AB phase fault occurs when, I ₀≈ 0 and I _α≈ 2I _β

When BC line to line fault earth fault occurs when, I ₀≠ 0 and I ₀≈-I _α-I _β

When the BC phase fault occurs when, I ₀≈ 0 and I _α≈-I _β

When AC line to line fault earth fault occurs when, I ₀≠ 0 and I ₀≈ 2I _α-I _β

When the AC phase fault occurs when, I ₀≈ 0 and

When the ABC three phase short circuit fault occurs when, I ₀≠ 0 and I ₀≠-I _α-I _β

Be consistent with the cable fault recognition methods in the step 3033.

Above simulation result has been verified feasibility and the validity of the power cable fault recognition methods that the present invention is based on fractal and wavelet transformation well, and the present invention can accurately identify and classifies the operating 10 kinds of short troubles of cable.

The above; it only is preferred embodiment of the present invention; be not that the present invention is imposed any restrictions, every any simple modification, change and equivalent structure of above embodiment being done according to the technology of the present invention essence changes, and all still belongs in the protection domain of technical solution of the present invention.

Claims (8)

1. one kind based on fractal and power cable fault recognition system wavelet transformation, it is characterized in that: comprise the current detection circuit module (1) of joining successively, signal conditioning circuit module (2), data collecting card (3) and main control computer (4), described current detection circuit module (1) comprises the A phase Hall current sensor (1-1) that detects in real time for the A phase current to threephase cable, be used for the B phase Hall current sensor (1-2) that the B phase current to threephase cable detects in real time and be used for mutually Hall current sensor (1-3) of C that the C phase current to threephase cable detects in real time, described signal conditioning circuit module (2) comprises the A phase current signal conditioning circuit module (2-1) of nursing one's health for to the signal of A phase Hall current sensor (1-1) output, be used for B phase current signal conditioning circuit module (2-2) that the signal of B phase Hall current sensor (1-2) output is nursed one's health and be used for the C phase current signal conditioning circuit module (2-3) nursed one's health of the signal of Hall current sensor (1-3) output mutually to C, described A phase current signal conditioning circuit module (2-1) is by the A phase I/V change-over circuit module (2-11) of joining successively, A phase signals amplifying circuit module (2-12) and A mutually filter circuit module (2-13) consist of, described B phase current signal conditioning circuit module (2-2) is by the B phase I/V change-over circuit module (2-21) of joining successively, B phase signals amplifying circuit module (2-22) and B mutually filter circuit module (2-23) consist of, and described C phase current signal conditioning circuit module (2-3) is by the C phase I/V change-over circuit module (2-31) of joining successively, C phase signals amplifying circuit module (2-32) and C mutually filter circuit module (2-33) consist of.

According to claimed in claim 1 based on fractal and power cable fault recognition system wavelet transformation, it is characterized in that: described A phase Hall current sensor (1-1) is the first closed loop Hall current sensor CHB-25NP, described the first closed loop Hall current sensor CHB-25NP is connected on the A phase line of cable by pin 1 and pin 6, pin 2 and its pin 10 of described the first closed loop Hall current sensor CHB-25NP join, pin 3 and its pin 9 of described the first closed loop Hall current sensor CHB-25NP join, pin 4 and its pin 8 of described the first closed loop Hall current sensor CHB-25NP join, pin 5 and its pin 7 of described the first closed loop Hall current sensor CHB-25NP join, pin 12 and the positive supply VCC of described the first closed loop Hall current sensor CHB-25NP join, and pin 13 and the negative supply-VCC of described the first closed loop Hall current sensor CHB-25NP join;

Described A phase I/V change-over circuit module (2-11) is made of resistance R 1a, and the pin 11 of the end of described resistance R 1a and the first closed loop Hall current sensor CHB-25NP joins, the other end ground connection of described resistance R 1a;

Described A phase signals amplifying circuit module (2-12) is by the first operational amplifier chip OP07CP, resistance R 2a, R3a, R4a and R5a, and diode D1a and D2a form; The pin 2 of described the first operational amplifier chip OP07CP and the end of resistance R 2a, the end of resistance R 4a, the positive pole of the negative pole of diode D1a and diode D2a joins, the end of the other end of described resistance R 2a and resistance R 1a joins, the pin 3 of described the first operational amplifier chip OP07CP and the end of resistance R 3a, the negative pole of the positive pole of diode D1a and diode D2a joins, the other end ground connection of described resistance R 3a, pin 4 and the negative supply-VCC of described the first operational amplifier chip OP07CP join, pin 7 and the positive supply VCC of described the first operational amplifier chip OP07CP join, and the pin 6 of described the first operational amplifier chip OP07CP joins with the other end of resistance R 4a and the end of resistance R 5a;

Described A phase filter circuit module (2-13) is by resistance R 6a, inductance L 1a, L2a, L3a, L4a, L5a, L6a and L7a, and capacitor C 1a, C2a and C3a form; The end of described inductance L 1a and the other end of resistance R 5a join, the end of the end of described inductance L 2a and the other end of inductance L 1a and inductance L 5a joins, the other end of described inductance L 5a is by capacitor C 1a ground connection, the end of the end of described inductance L 3a and the other end of inductance L 2a and inductance L 6a joins, the other end of described inductance L 6a is by capacitor C 2a ground connection, the end of the end of described inductance L 4a and the other end of inductance L 3a and inductance L 7a joins, the other end of described inductance L 7a is by capacitor C 3a ground connection, the other end of described inductance L 4a is by resistance R 6a ground connection, and the other end of described inductance L 4a is the output terminals A-OUT of described A phase filter circuit module (2-13) and joins with the signal input part of data collecting card (3).

According to claimed in claim 1 based on fractal and power cable fault recognition system wavelet transformation, it is characterized in that: described B phase Hall current sensor (1-2) is the second closed loop Hall current sensor CHB-25NP, described the second closed loop Hall current sensor CHB-25NP is connected on the B phase line of cable by pin 1 and pin 6, pin 2 and its pin 10 of described the second closed loop Hall current sensor CHB-25NP join, pin 3 and its pin 9 of described the second closed loop Hall current sensor CHB-25NP join, pin 4 and its pin 8 of described the second closed loop Hall current sensor CHB-25NP join, pin 5 and its pin 7 of described the second closed loop Hall current sensor CHB-25NP join, pin 12 and the positive supply VCC of described the second closed loop Hall current sensor CHB-25NP join, and pin 13 and the negative supply-VCC of described the second closed loop Hall current sensor CHB-25NP join;

Described B phase I/V change-over circuit module (2-21) is made of resistance R 1b, and the pin 11 of the end of described resistance R 1b and the second closed loop Hall current sensor CHB-25NP joins, the other end ground connection of described resistance R 1b;

Described B phase signals amplifying circuit module (2-22) is by the second operational amplifier chip OP07CP, resistance R 2b, R3b, R4b and R5b, and diode D1b and D2b form; The pin 2 of described the second operational amplifier chip OP07CP and the end of resistance R 2b, the end of resistance R 4b, the positive pole of the negative pole of diode D1b and diode D2b joins, the end of the other end of described resistance R 2b and resistance R 1b joins, the pin 3 of described the second operational amplifier chip OP07CP and the end of resistance R 3b, the negative pole of the positive pole of diode D1b and diode D2b joins, the other end ground connection of described resistance R 3b, pin 4 and the negative supply-VCC of described the second operational amplifier chip OP07CP join, pin 7 and the positive supply VCC of described the second operational amplifier chip OP07CP join, and the pin 6 of described the second operational amplifier chip OP07CP joins with the other end of resistance R 4b and the end of resistance R 5b;

Described B phase filter circuit module (2-23) is by resistance R 6b, inductance L 1b, L2b, L3b, L4b, L5b, L6b and L7b, and capacitor C 1b, C2b and C3b form; The end of described inductance L 1b and the other end of resistance R 5b join, the end of the end of described inductance L 2b and the other end of inductance L 1b and inductance L 5b joins, the other end of described inductance L 5b is by capacitor C 1b ground connection, the end of the end of described inductance L 3b and the other end of inductance L 2b and inductance L 6b joins, the other end of described inductance L 6b is by capacitor C 2b ground connection, the end of the end of described inductance L 4b and the other end of inductance L 3b and inductance L 7b joins, the other end of described inductance L 7b is by capacitor C 3b ground connection, the other end of described inductance L 4b is by resistance R 6b ground connection, and the other end of described inductance L 4b is the output terminal B-OUT of described B phase filter circuit module (2-23) and joins with the signal input part of data collecting card (3).

According to claimed in claim 1 based on fractal and power cable fault recognition system wavelet transformation, it is characterized in that: described C phase Hall current sensor (1-3) is the 3rd closed loop Hall current sensor CHB-25NP, described the 3rd closed loop Hall current sensor CHB-25NP is connected on the C phase line of cable by pin 1 and pin 6, pin 2 and its pin 10 of described the 3rd closed loop Hall current sensor CHB-25NP join, pin 3 and its pin 9 of described the 3rd closed loop Hall current sensor CHB-25NP join, pin 4 and its pin 8 of described the 3rd closed loop Hall current sensor CHB-25NP join, pin 5 and its pin 7 of described the 3rd closed loop Hall current sensor CHB-25NP join, pin 12 and the positive supply VCC of described the 3rd closed loop Hall current sensor CHB-25NP join, and pin 13 and the negative supply-VCC of described the 3rd closed loop Hall current sensor CHB-25NP join;

Described C phase I/V change-over circuit module (2-31) is made of resistance R 1c, and the pin 11 of the end of described resistance R 1c and the 3rd closed loop Hall current sensor CHB-25NP joins, the other end ground connection of described resistance R 1c;

Described C phase signals amplifying circuit module (2-32) is by the 3rd operational amplifier chip OP07CP, resistance R 2c, R3c, R4c and R5c, and diode D1c and D2c form; The pin 2 of described the 3rd operational amplifier chip OP07CP and the end of resistance R 2c, the end of resistance R 4c, the positive pole of the negative pole of diode D1c and diode D2c joins, the end of the other end of described resistance R 2c and resistance R 1c joins, the pin 3 of described the 3rd operational amplifier chip OP07CP and the end of resistance R 3c, the negative pole of the positive pole of diode D1c and diode D2c joins, the other end ground connection of described resistance R 3c, pin 4 and the negative supply-VCC of described the 3rd operational amplifier chip OP07CP join, pin 7 and the positive supply VCC of described the 3rd operational amplifier chip OP07CP join, and the pin 6 of described the 3rd operational amplifier chip OP07CP joins with the other end of resistance R 4c and the end of resistance R 5c;

Described C phase filter circuit module (2-33) is by resistance R 6c, inductance L 1c, L2c, L3c, L4c, L5c, L6c and L7c, and capacitor C 1c, C2c and C3c form; The end of described inductance L 1c and the other end of resistance R 5c join, the end of the end of described inductance L 2c and the other end of inductance L 1c and inductance L 5c joins, the other end of described inductance L 5c is by capacitor C 1c ground connection, the end of the end of described inductance L 3c and the other end of inductance L 2c and inductance L 6c joins, the other end of described inductance L 6c is by capacitor C 2c ground connection, the end of the end of described inductance L 4c and the other end of inductance L 3c and inductance L 7c joins, the other end of described inductance L 7c is by capacitor C 3c ground connection, the other end of described inductance L 4c is by resistance R 6c ground connection, and the other end of described inductance L 4c is the output terminal C-OUT of described C phase filter circuit module (2-33) and joins with the signal input part of data collecting card (3).

According to claimed in claim 1 based on fractal and power cable fault recognition system wavelet transformation, it is characterized in that: described data collecting card (3) is the PCI6221 data collecting card, described main control computer (4) is the computing machine with the PCI slot, and described PCI6221 data collecting card is inserted on the described PCI slot.

One kind utilize system as claimed in claim 1 based on fractal and power cable fault recognition methods wavelet transformation, it is characterized in that the method may further comprise the steps:

Step 1, signal detect in real time and upload synchronously: detect in real time by the A phase current of A phase Hall current sensor (1-1) to detected cable, and with the real-time A phase current signal i that detects _aSuccessively by A phase I/V change-over circuit module (2-11), A phase signals amplifying circuit module (2-12) and A mutually filter circuit module (2-13) carry out being uploaded to synchronously data collecting card (3) after I/V conversion, amplification and filtering are processed; By B phase Hall current sensor (1-2) the B phase current that is identified cable is detected in real time, and with the real-time B phase current signal i that detects _bSuccessively by B phase I/V change-over circuit module (2-21), B phase signals amplifying circuit module (2-22) and B mutually filter circuit module (2-23) carry out being uploaded to synchronously data collecting card (3) after I/V conversion, amplification and filtering are processed; By C phase Hall current sensor (1-3) the C phase current that is identified cable is detected in real time, and with the real-time C phase current signal i that detects _cSuccessively by C phase I/V change-over circuit module (2-31), C phase signals amplifying circuit module (2-32) and C mutually filter circuit module (2-33) carry out being uploaded to synchronously data collecting card (3) after I/V conversion, amplification and filtering are processed;

Step 2, signals collecting and storage: data collecting card (3) is to A phase current signal i _a, B phase current signal i _bWith C phase current signal i _cAfter gathering the also corresponding A/D of carrying out conversion, synchronous driving is to main control computer (4); Simultaneously, by main control computer (4) A phase current signal i _aB phase current signal i _bWith C phase current signal i _cSampled point quantity, all sampled points and the corresponding sampling instant of each sampled point store;

Step 3, cable fault identification: when detected cable breaks down, the A phase current signal i that data collecting card (3) sends _a, B phase current signal i _bWith C phase current signal i _cBe fault-signal, this moment is by the A phase current signal i of main control computer (4) to being sent by data collecting card (3) _a, B phase current signal i _bWith C phase current signal i _cCarry out analyzing and processing, and the corresponding fault type that draws detected cable belongs to any in A phase ground short circuit fault, B phase ground short circuit fault, C phase ground short circuit fault, AB line to line fault earth fault, AB phase fault, BC line to line fault earth fault, BC phase fault, AC line to line fault earth fault, AC phase fault and the ABC three phase short circuit fault, and its analyzing and processing process is as follows:

Step 301, employing fractal method carry out cable fault just to be identified, and detailed process is:

Step 3011, current waveform figure are drawn: described main control computer (4) calls the current waveform drafting module and draws out A phase current signal i _aA phase current waveform figure, B phase current signal i with sampling time t variation _bB phase current waveform figure and C phase current signal i with sampling time t variation _cC phase current waveform figure with sampling time t variation;

Step 3012, fractal dimension calculate: at first, suppose that the A phase current waveform is the bounded set of points F of Euclidean space _A, be ε with the length of side _ALattice cover this point set F _AThe time, suppose N _A(ε _A) for the length of side be ε _AShi Qizhong comprises point set F _AIn the non-NULL lattice number of point, described main control computer (4) calls the fractal dimension computing module and according to formula

Calculate A phase fractal dimension D _AThen, suppose that the B phase current waveform is the bounded set of points F of Euclidean space _B, be ε with the length of side _BLattice cover this point set F _BThe time, suppose N _B(ε _B) for the length of side be ε _BShi Qizhong comprises point set F _BIn the non-NULL lattice number of point, described main control computer (4) calls the fractal dimension computing module and according to formula

Calculate B phase fractal dimension D _BThen, suppose that the C phase current waveform is the bounded set of points F of Euclidean space _C, be ε with the length of side _CLattice cover this point set F _CThe time, suppose N _C(ε _C) for the length of side be ε _CShi Qizhong comprises point set F _CIn the non-NULL lattice number of point, described main control computer (4) calls the fractal dimension computing module and according to formula

Calculate C phase fractal dimension D _C

Step 3013, the comparison of three-phase fractal dimension and cable fault are just identified: described main control computer (4) is with A phase fractal dimension D _A, B phase fractal dimension D _BWith C fractal dimension D mutually _CCompare, and divide five kinds of situations that cable fault is carried out just identification according to comparison result:

Work as D _B＜D _C＜D _AThe time, being judged to be A phase ground short circuit fault, end of identification is also exported recognition result;

Work as D _A＜D _B＜D _CThe time, being judged to be C phase ground short circuit fault, end of identification is also exported recognition result;

Work as D _C＜D _A＜D _BThe time, be judged to be B phase ground short circuit fault, AB line to line fault earth fault or AB phase fault, execution in step 302;

Work as D _A＜D _C＜D _BThe time, be judged to be ABC three phase short circuit fault, BC line to line fault earth fault or BC phase fault, execution in step 302;

Work as D _B＜D _A＜D _CThe time, be judged to be AC line to line fault earth fault or AC phase fault, execution in step 302;

Step 302, described main control computer (4) call triumphant human relations boolean conversion module with A phase current signal i _a, B phase current signal i _bWith C phase current signal i _cTransform to the modular space from phase space, obtain 0 mould current component i ₀, α mould current component i _αWith β mould current component i _β:

$i_0=\frac{1}{3}(i_a+i_b+i_c)$

$i_{\mathrm{\α}}=\frac{1}{3}(i_a-i_b)$

$i_{\mathrm{\β}}=\frac{1}{3}(i_a-i_c)$

Step 303, employing wavelet transform carry out cable fault to be identified again, and detailed process is:

Step 3031, wavelet transform and wavelet coefficient are found the solution: at first, described main control computer (4) is chosen 0 mould current component i ₀As one-dimensional signal f (n ₀) and call the wavelet transform module to one-dimensional signal f (n ₀) carry out wavelet transform, corresponding each layer wavelet coefficient of trying to achieve behind the wavelet transform, the described wavelet coefficient of each layer comprises each layer approximation coefficient and each layer detail coefficients, wherein the described detail coefficients of each layer is denoted as d _{J, k}, wherein, n ₀=0,1,2 ... N-1 and N are one-dimensional signal f (n ₀) sample sequence in sampled point quantity, one-dimensional signal f (n ₀) sample sequence in sampled point quantity, all sample sequence points and each sample sequence put corresponding sampling instant all with step 2 in the A phase current signal i that stores of main control computer (4) _a, B phase current signal i _bWith C phase current signal i _cSampled point quantity, all sampled points and the corresponding sampling instant of each sampled point corresponding one by one; J=1,2 ..., J and J are the number of plies of wavelet transform, k=0,1,2 ..., N-1 and k are one-dimensional signal f (n ₀) sample sequence in the sequence number of N sample sequence point; Then, described main control computer (4) is chosen α mould current component i _αAs one-dimensional signal f (n _α) and call the wavelet transform module to one-dimensional signal f (n _α) carry out wavelet transform, corresponding each layer wavelet coefficient of trying to achieve behind the wavelet transform, the described wavelet coefficient of each layer comprises each layer approximation coefficient and each layer detail coefficients, wherein the described detail coefficients of each layer is denoted as d' _{J, k}, wherein, n _α=0,1,2 ... N-1 and N are one-dimensional signal f (n _α) sample sequence in sampled point quantity, one-dimensional signal f (n _α) sample sequence in sampled point quantity, all sample sequence points and each sample sequence put corresponding sampling instant all with step 2 in the A phase current signal i that stores of main control computer (4) _a, B phase current signal i _bWith C phase current signal i _cSampled point quantity, all sampled points and the corresponding sampling instant of each sampled point corresponding one by one; J=1,2 ..., J and J are the number of plies of wavelet transform, k=0,1,2 ..., N-1 and k are one-dimensional signal f (n _α) sample sequence in the sequence number of N sample sequence point; Then, described main control computer (4) is chosen β mould current component i _βAs one-dimensional signal f (n _β) and call the wavelet transform module to one-dimensional signal f (n _β) carry out wavelet transform, corresponding each layer wavelet coefficient of trying to achieve behind the wavelet transform, the described wavelet coefficient of each layer comprises each layer approximation coefficient and each layer detail coefficients, wherein the described detail coefficients of each layer is denoted as d'' _{J, k}, wherein, n _β=0,1,2 ... N-1 and N are one-dimensional signal f (n _β) sample sequence in sampled point quantity, one-dimensional signal f (n _β) sample sequence in sampled point quantity, all sample sequence points and each sample sequence put corresponding sampling instant all with step 2 in the A phase current signal i that stores of main control computer (4) _a, B phase current signal i _bWith C phase current signal i _cSampled point quantity, all sampled points and the corresponding sampling instant of each sampled point corresponding one by one; J=1,2 ..., J and J are the number of plies of wavelet transform, k=0,1,2 ..., N-1 and k are one-dimensional signal f (n _β) sample sequence in the sequence number of N sample sequence point;

Step 3032, modulus maximum point detect: at first, and according to one-dimensional signal f (n ₀) the sampling order of sample sequence, from front to back to J layer detail coefficients d _{J, k}The modulus maximum point detect and record, and detect and to draw when k=i d _{J, k}Obtain the modulus maximum point, i.e. 0 mould current component i ₀Initial row mode maximum value I ₀=d _{J, i}Then, according to one-dimensional signal f (n _α) the sampling order of sample sequence, from front to back to J layer detail coefficients d' _{J, k}The modulus maximum point detect and record, and detect and to draw when k=i d' _{J, k}Obtain the modulus maximum point, i.e. α mould current component i _αInitial row mode maximum value I _α=d' _{J, i}Then, according to one-dimensional signal f (n _β) the sampling order of sample sequence, from front to back to J layer detail coefficients d'' _{J, k}The modulus maximum point detect and record, and detect and to draw when k=i d'' _{J, k}Obtain the modulus maximum point, i.e. β mould current component i _βInitial row mode maximum value I _β=d'' _{J, i}Wherein, i=0,1,2 ..., N-1;

Step 3033, the comparison of three initial row mode maximum value and cable fault are identified again: described main control computer (4) minute D _C＜D _A＜D _B, D _A＜D _C＜D _BAnd D _B＜D _A＜D _CThree kinds of situations are with 0 mould current component i ₀Initial row mode maximum value I ₀, α mould current component i _αInitial row mode maximum value I _αWith β mould current component i _βInitial row mode maximum value I _βCompare, and according to comparison result cable fault identified again, be specially:

Work as D _C＜D _A＜D _BThe time, at first judged whether I ₀=0, work as I ₀, judged whether I at=0 o'clock _α=2I _β, work as I ₀=0 and I _α=2I _βThe time, be judged as the AB phase fault; Work as I ₀, at first judged whether I at ≠ 0 o'clock _β=0 and | I ₀|=| I _α|, work as I ₀≠ 0, I _β=0 and | I ₀|=| I _α| the time, be judged as B phase ground short circuit fault; Then judged whether I ₀=2I _β-I _α, work as I ₀≠ 0 and I ₀=2I _β-I _αThe time, be judged as AB line to line fault earth fault; End of identification is also exported recognition result;

Work as D _A＜D _C＜D _BThe time, at first judged whether I ₀=0, work as I ₀, judged whether I at=0 o'clock _α=-I _β, work as I ₀=0 and I _α=-I _βThe time, be judged as the BC phase fault; Work as I ₀, judged whether I at ≠ 0 o'clock ₀=-I _α-I _β, work as I ₀≠ 0 and I ₀=-I _α-I _βThe time, be judged as BC line to line fault earth fault; Work as I ₀≠ 0 and I ₀≠-I _α-I _βThe time, be judged as the ABC three phase short circuit fault; End of identification is also exported recognition result;

Work as D _B＜D _A＜D _CThe time, at first judged whether I ₀=0, work as I ₀, work as I at=0 o'clock ₀=0 o'clock, judged whether

Work as I ₀=0 and

The time, be judged as the AC phase fault; Work as I ₀, judged whether I at ≠ 0 o'clock ₀=2I _α-I _β, work as I ₀≠ 0 and I ₀=2I _α-I _βThe time, be judged as AC line to line fault earth fault; End of identification is also exported recognition result.

7. it is characterized in that in accordance with the method for claim 6: ε described in the step 3012 _A, ε _BAnd ε _CValue equate.

8. it is characterized in that in accordance with the method for claim 6: the value of J described in the step 3031 and 3032 is 3.

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