Calculation method of single-phase high-resistance grounding impedance in distribution network using wavelet transform energy
A technology of impedance calculation and high-impedance grounding, which is applied in the direction of measuring electricity, measuring electrical variables, measuring devices, etc., and can solve problems such as difficult positioning
Active Publication Date: 2020-11-24
JIANGSU ANFANG ELECTRIC POWER TECH +1
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Problems solved by technology
Due to the complex topology the system has difficulty in locating faults occurring in the network
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[0053] Such as Figure 1-5 As shown, the method for calculating the single-phase high-resistance grounding impedance of the distribution network using wavelet transform energy of the present invention, the specific process is as follows:
[0054] 1) Use the simulation software SLGF to establish a distribution network simulation model;
[0055] 2) Establish impedance prediction sample database DB impedance ;
[0056] S1. Select the node Node equidistantly on the simulated line i (i=1,2,3,...,35), simulate different high-resistance faults at each node, and the impedance value is Z n , n=1,2,...,7, the impedance value is selected from the set {40, 50, 60, 70, 80, 90, 100};
[0057] S2. Simulate fault Z at node i n , measure the 3-phase current I of 5 cycles before and after the fault occurs at the head end of the line iz and the voltage signal U iz The time-domain waveform of the voltage and current waveforms is decomposed by two layers of wavelet packets, the mother wavel...
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The invention discloses a method for calculating single-phase high resistance grounding impedance of a distribution network by using wavelet transform energy. The method includes the following steps that (1) an impedance prediction sample database is established; (2) a single-phase high resistance fault impedance prediction regression model is trained; (3) three-phase current and voltage time domain waveforms of M cycles are measured at the head end of a line, the time domain waveforms are decomposed by offline wavelets, and an energy value of a wavelet coefficient in each power frequency cycle is calculated, energy of three-phase current and voltage wavelet coefficients of the M cycles is substituted into the regression model to predict a fault impedance value and calculate the fault impedance value. According to the method for calculating the single-phase high resistance grounding impedance of the distribution network by using the wavelet transform energy, faults can be judged automatically according to variation trend of wavelet coefficient energy in multiple continuous cycles, and an error between a fault point impedance calculated value and a true value is less than 0.42%.
Description
technical field [0001] The invention relates to a method for calculating the single-phase high-resistance grounding impedance of a distribution network by using wavelet transform energy, and belongs to the technical field of fault location of distribution network lines. Background technique [0002] A typical distribution network consists of several feeders with some lateral branches. Due to the complex topology of the system it is difficult to locate the faults that occur in the network. Therefore, a reliable and accurate method is crucial to identify the fault impedance and determine its location, especially when high-resistance faults occur. There are many reasons for distribution network failure, for example, common causes of overhead lines are lightning strikes, tree branches touching and animal encroachment, etc. In underground networks, failures are often attributed to deterioration of cable insulation and water tree phenomena. Contents of the invention [0003] ...
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IPC IPC(8): G01R31/08
CPCG01R31/086G01R31/088
Inventor 许杏桃汪洋许胜罗威刘贵恒胡春花赵超李荣胜
Owner JIANGSU ANFANG ELECTRIC POWER TECH