CN114689997B - Distribution network cable fault identification and positioning method - Google Patents
Distribution network cable fault identification and positioning method Download PDFInfo
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- CN114689997B CN114689997B CN202210486155.5A CN202210486155A CN114689997B CN 114689997 B CN114689997 B CN 114689997B CN 202210486155 A CN202210486155 A CN 202210486155A CN 114689997 B CN114689997 B CN 114689997B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/088—Aspects of digital computing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/11—Locating faults in cables, transmission lines, or networks using pulse reflection methods
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Abstract
The invention provides a distribution network cable fault identification and positioning method, which comprises the following steps: 1. acquiring a fault reflection waveform y (t); 2. obtaining fault-free reflected waveforms y 0 (t); 3. subtracting the fault-free reflected waveform y from the fault reflected waveform y (t) 0 Obtaining waveform y by taking absolute value of signal obtained in (t) 1 (t); 4. for waveform y 1 (t) performing time inversion to obtain an inversion waveform y 1 (T-T); 5. will invert waveform y 1 (T-T) injecting the voltage waveforms into a simulation model 2 provided with N detection points to simulate the voltage waveforms of the N detection points; 6. and carrying out fault location according to the energy spectrum. The invention is suitable for positioning the faults of different types of cables, can accurately and quickly position various fault types of the distribution network cable, and has the advantages of high measurement precision, strong noise resistance and the like.
Description
Technical Field
The invention relates to a distribution network cable fault identification and positioning method, and belongs to the technical field of distribution cable fault positioning.
Background
The cable is widely applied to power distribution systems of power grids and power supply systems in the industries of railways, aviation, manufacturing and the like; in order to avoid the influence of external forces such as lightning strokes, wind damages and the like, the cable is generally buried in the system or underground, so that the fault of the cable cannot be identified and positioned like an overhead line through inspection, and a special fault positioning method is needed.
The traveling wave method represented by the time domain reflection method is used as a main fault positioning method of the power transmission line, and the fault can be diagnosed and the position estimated by measuring the transient response of the propagation and reflection of the electromagnetic traveling wave in the line; although the method has a plurality of advantages, the method has the problems that the signal of the secondary reflection wave head is weak and is not easy to identify during single-end ranging; the accurate time for the traveling wave to reach the line terminal is acquired by GPS assistance during double-end ranging to realize double-end synchronous sampling, so that the cost is increased, and the application of the traveling wave method is limited to a certain extent; in addition, the power distribution network often has a complex topological structure, and the analysis difficulty of the reflected signals of the traveling wave method is greatly increased.
Time Reversal (TR) technology utilizes the Time symmetry of wave equation to turn over the observed signal in the observation point in Time and inject it into the original system, and utilizes the focusing characteristic in Time and space of fault point formation to implement fault location; in the power distribution network, for fault location of multiple branch lines, firstly, a fault section is determined, namely, a fault occurs on which branch line, and then, fault location is completed by using a method of no-branch line ranging, but the traditional time reversal algorithm has higher dependency on fault type and transition resistance, and can only locate single type of faults.
Disclosure of Invention
The invention provides a distribution network cable fault identification and positioning method, and aims to solve the problem that the cable fault in a distribution network cannot be effectively identified and positioned in the prior art.
The technical solution of the invention is as follows: a distribution network cable fault identification and positioning method comprises the following steps:
1. acquiring a fault reflection waveform y (t);
2. obtaining fault-free reflected waveforms y 0 (t)；
3. Subtracting the fault-free reflected waveform y from the fault reflected waveform y (t) 0 Obtaining waveform y by taking absolute value of signal obtained in (t) 1 (t)；
4. For waveform y 1 (t) performing time inversion to obtain an inversion waveform y 1 (T-t)；
5. Will invert waveform y 1 (T-T) injecting the voltage waveforms into a simulation model 2 provided with N detection points to simulate the voltage waveforms of the N detection points;
6. and carrying out fault location according to the energy spectrum.
Further, the acquiring the fault reflection waveform y (t) specifically includes the following steps:
1-1, generating an incident pulse f (t) by a pulse generator device;
1-2, injecting an incident pulse f (t) at the head end of the fault cable, and detecting and acquiring a fault reflection waveform y (t).
Further, the acquiring of the fault-free reflection waveform y 0 (t) specifically comprises the following steps:
2-1, acquiring related parameters of a distribution cable needing fault location, and establishing a fault-free simulation model 1 in a Simulink;
2-2 obtaining a fault-free reflected waveform y generated under the condition that an incident pulse f (t) is injected into the head end of the fault-free cable in the simulation model 1 0 (t)。
Further, the pair of waveforms y 1 (t) performing time inversion to obtain an inversion waveform y 1 (T-T), specifically comprising: for waveform y 1 (T) performing time inversion and performing additional time delay T to obtain an inversion waveform y 1 (T-t)。
Further, the waveform y is inverted 1 (T-T) injecting the voltage waveforms into a simulation model 2 provided with N detection points for simulation, and obtaining the voltage waveforms of the N detection points, wherein the method specifically comprises the following steps of:
3-1, establishing a simulation model 2 in a Simulink, setting N detection points on a fault-free cable in the simulation model 2 according to a measurement interval d input by a user to detect voltage waveforms of the fault-free cable, and numbering each detection point, wherein N is equal to the cable length/d-1;
3-2, inverting waveform y 1 (T-T) head-end injection into the fault-free cable in simulation model 2;
and 3-3, running the simulation model 2, acquiring voltage waveforms of N detection points and recording.
Further, the fault location according to the energy spectrum specifically includes the following steps:
4-1, measuring the voltage wave energy of each detection point;
4-2 by finding the energy maxima of the voltage wave energy.
Further, the measuring the voltage wave energy of each detection point specifically includes:
4-1-1, calculating voltage wave energy of each detection point according to the voltage waveforms of the N detection points obtained in the step 5;
4-1-2, obtaining the position-energy spectrogram of the whole distribution cable according to the corresponding relation between the voltage wave energy of each detection point and each detection point.
Further, the energy value of the voltage wave energy is calculated as follows:
wherein E (x) is the energy value of the voltage wave energy, T is the total duration of the voltage wave signal, u x (j) The voltage value of the jth step of the xth detection point is simulated by the simulation model 2, delta t is the simulation step length, and M is the simulation step number.
Further, the energy maximum point of the voltage wave energy is the fault position of the fault cable.
The invention has the beneficial effects that:
1) The invention is suitable for positioning the faults of different types of cables, can accurately and quickly position various fault types of the distribution network cable, and has the advantages of high measurement precision, strong noise resistance and the like;
2) The time domain reflection method and the time inversion method are combined and utilized, so that the method has strong applicability, high flexibility and low use cost;
3) Subtracting the fault-free reflection waveform from the actual fault reflection waveform, and solving the problem that the tail end information is lost under the total reflection phenomena such as open circuit fault, ground fault and the like in time reversal fault positioning so as to be incapable of focusing; the method has the characteristics of obvious positioning result, high accuracy, strong noise resistance and the like;
4) The invention can realize fault location of branch-free lines, and solves the problem that the time reversal algorithm has higher dependence on fault types and transition resistance and the problem that only single type of faults are located in the prior art.
Drawings
Fig. 1 is a general flow diagram of a distribution network cable fault identification and localization method according to the present invention.
Fig. 2 is a schematic diagram of the obtained fault reflection waveform y (t).
FIG. 3 is an obtained fault-free reflected waveform y 0 (t) (terminal reflection waveform) schematic.
FIG. 4 is |y (t) -y 0 Waveform y obtained by (t) | 1 (t) schematic.
FIG. 5 is an inverted waveform y 1 (T-T) schematic diagram.
Fig. 6 is a position-energy spectrum, and the focus point is the fault point.
Detailed Description
A distribution network cable fault identification and positioning method comprises the following steps:
1. acquiring a fault reflection waveform y (t);
2. obtaining fault-free reflected waveforms y 0 (t) (terminal reflection waveform);
3. subtracting the fault-free reflected waveform y from the fault reflected waveform y (t) 0 Obtaining waveform y by taking absolute value of signal obtained in (t) 1 (t); fault reflected waveform y (t) minus non-fault reflected waveform y 0 (t) is equivalent to only remaining fault points and tail end information, and the supplementation of the tail end information can enhance the focusing degree of time reversal at the fault points, so that the problem that the time reversal algorithm has higher dependence on fault types and transition resistance and the problem that in the prior art, only single type of faults are positioned are solved;
4. for waveform y 1 (t) performing time inversion to obtain an inversion waveform y 1 (T-t)；
5. Will invert waveform y 1 (T-T) injectionSetting a simulation model 2 of N detection points to simulate to obtain voltage waveforms of the N detection points;
6. and carrying out fault location according to the energy spectrum.
The method for acquiring the fault reflection waveform y (t) specifically comprises the following steps:
1-1, generating an incident pulse f (t) by a pulse generator device;
1-2, injecting an incident pulse f (t) at the head end of the fault cable, and detecting and acquiring a fault reflection waveform y (t).
The acquisition of fault-free reflected waveform y 0 (t) (terminal reflection waveform); the method specifically comprises the following steps:
2-1, acquiring related parameters of a distribution cable needing fault location, and establishing a fault-free simulation model 1 in a Simulink; the simulation model 1 is used for simulating the injection of an incident pulse f (t) at the head end of the fault-free cable and detecting and obtaining a fault-free reflection waveform y 0 The cable model of (t);
2-2 obtaining a fault-free reflected waveform y generated under the pulse of the first-end injection incident pulse f (t) of the fault-free cable in the simulation model 1 0 (t) (fault-free reflected waveform y 0 And (t) is the terminal reflection waveform).
The pair of waveforms y 1 (t) performing time inversion to obtain an inversion waveform y 1 (T-T), specifically comprising: for waveform y 1 (T) performing time inversion and performing additional time delay T to obtain an inversion waveform y 1 (T-t)。
The waveform y will be inverted 1 (T-T) injecting the voltage waveforms into a simulation model 2 provided with N detection points for simulation, and obtaining the voltage waveforms of the N detection points, wherein the method specifically comprises the following steps of:
3-1, establishing a simulation model 2 in a Simulink, setting N detection points on the fault-free cable simulated in the simulation model 2 according to a measurement interval d input by a user to detect voltage waveforms of the fault-free cable, and numbering each detection point, wherein N is equal to the cable length/d-1; the simulation model 2 is to inject inversion waveform y into the head end of the fault-free cable 1 The fault-free cable model of (T-T);
3-2, inverting waveform y 1 (T-T) head-end injection into the fault-free cable in simulation model 2;
and 3-3, running the simulation model 2, acquiring voltage waveforms of N detection points and recording.
The fault location according to the energy spectrum specifically comprises the following steps:
4-1, measuring the voltage wave energy of each detection point;
4-2, achieving the purpose of fault location by finding an energy maximum point of the voltage wave energy; the maximum point of energy focusing as in fig. 6 is the fault location of the cable.
The measuring of the voltage wave energy of each detection point specifically comprises:
4-1-1, calculating voltage wave energy of each detection point according to the voltage waveforms of the N detection points obtained in the step 5, wherein the energy value calculation formula of the voltage wave energy is as follows:
wherein E (x) is the energy value of the voltage wave energy, T is the total duration of the voltage wave signal, u x (j) The voltage value of the jth step of the xth detection point is simulated by the simulation model 2, delta t is the simulation step length, and M is the simulation step number;
4-1-2, obtaining the position-energy spectrogram of the whole distribution cable according to the corresponding relation between the voltage wave energy of each detection point and each detection point.
Claims (7)
1. A distribution network cable fault identification and positioning method is characterized by comprising the following steps:
1. acquiring a fault reflection waveform y (t);
2. obtaining fault-free reflected waveforms y 0 (t)；
3. Subtracting the fault-free reflected waveform y from the fault reflected waveform y (t) 0 Obtaining waveform y by taking absolute value of signal obtained in (t) 1 (t)；
4. For waveform y 1 (t) performing time inversion to obtain an inversion waveform y 1 (T-t)；
5. Will invert waveform y 1 (T-T) injecting the voltage waveforms into a simulation model 2 provided with N detection points to simulate the voltage waveforms of the N detection points;
6. fault location is carried out according to the energy spectrum;
the fault location according to the energy spectrum specifically comprises the following steps:
4-1, measuring the voltage wave energy of each detection point;
4-2, by finding the energy maximum point of the voltage wave energy;
and the energy maximum point of the voltage wave energy is the fault position of the fault cable.
2. The method for identifying and locating a distribution network cable fault according to claim 1, wherein the step of obtaining the fault reflection waveform y (t) comprises the following steps:
1-1, generating an incident pulse f (t) by a pulse generator device;
1-2, injecting an incident pulse f (t) at the head end of the fault cable, and detecting and acquiring a fault reflection waveform y (t).
3. The method for identifying and locating faults of distribution network cables according to claim 1, wherein the fault-free reflection waveform y is obtained 0 (t) specifically comprises the following steps:
2-1, acquiring related parameters of a distribution cable needing fault location, and establishing a fault-free simulation model 1 in a Simulink;
2-2 obtaining a fault-free reflected waveform y generated under the condition that an incident pulse f (t) is injected into the head end of the fault-free cable in the simulation model 1 0 (t)。
4. The method for identifying and locating a distribution network cable fault as recited in claim 1, wherein said pair of waveforms y 1 (t) performing time inversion to obtain an inversion waveform y 1 (T-T), specifically comprising: for waveform y 1 (T) performing time inversion and performing additional time delay T to obtain an inversion waveform y 1 (T-t)。
5. The method for identifying and locating a distribution network cable fault as recited in claim 1, wherein said inverting waveform y 1 (T-T) injecting the voltage waveforms into a simulation model 2 provided with N detection points for simulation, and obtaining the voltage waveforms of the N detection points, wherein the method specifically comprises the following steps of:
3-1, establishing a simulation model 2 in a Simulink, setting N detection points on a fault-free cable in the simulation model 2 according to a measurement interval d input by a user to detect voltage waveforms of the fault-free cable, and numbering each detection point, wherein N is equal to the cable length/d-1;
3-2, inverting waveform y 1 (T-T) head-end injection into the fault-free cable in simulation model 2;
and 3-3, running the simulation model 2, acquiring voltage waveforms of N detection points and recording.
6. The method for identifying and locating a distribution network cable fault according to claim 1, wherein the measuring the voltage wave energy of each detection point specifically comprises:
4-1-1, calculating voltage wave energy of each detection point according to the voltage waveforms of the N detection points obtained in the step 5;
4-1-2, obtaining the position-energy spectrogram of the whole distribution cable according to the corresponding relation between the voltage wave energy of each detection point and each detection point.
7. The method for identifying and locating a distribution network cable fault according to claim 6, wherein the energy value of the voltage wave energy is calculated as follows:
wherein E (x) is the energy value of the voltage wave energy, T is the total duration of the voltage wave signal, u x (j) The voltage value of the jth step of the xth detection point is simulated by the simulation model 2, delta t is the simulation step length, and M is the simulation step number.
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