Looking for breakthrough ideas for innovation challenges? Try Patsnap Eureka!

Power distribution network fault circuit selection method based on transient zero-sequence current time-frequency characteristic vectors

A technology of distribution network faults and time-frequency characteristics, applied in the fault location and other directions, can solve the problems of complex fault boundaries, randomness, and decreased sensitivity of high-frequency transient line selection methods.

Active Publication Date: 2013-08-14
KUNMING UNIV OF SCI & TECH
View PDF7 Cites 44 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Distribution network faults are mostly single-phase ground faults, and the problem of line selection has been difficult to solve. The main reasons are: 1. The fault boundary is complex and random, such as the initial phase angle of the fault, the fault distance, and the size of the transition resistance
Different fault conditions, transient zero-sequence signal frequency components, attenuation characteristics, and spectrum energy distribution are quite different; 2. When a single-phase ground fault occurs near the voltage zero-crossing point, the high-frequency components caused are very small, and the high-frequency transient quantity is selected The sensitivity of the line method is greatly reduced; 3. The electrical characteristics of the cable line and the overhead line and the length of each line are quite different, and the similarity between the zero-sequence current waveforms of the sound line becomes worse; 4. When the traveling wave detection method is used, due to the traveling wave propagation The speed is fast, but the distribution network line is short, and the signal interference of the distribution network is more, so it is difficult to capture the first wave head of the traveling wave reliably

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Power distribution network fault circuit selection method based on transient zero-sequence current time-frequency characteristic vectors
  • Power distribution network fault circuit selection method based on transient zero-sequence current time-frequency characteristic vectors
  • Power distribution network fault circuit selection method based on transient zero-sequence current time-frequency characteristic vectors

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Example 1: The single-phase ground fault simulation model of 110kV / 35kV distribution network is as follows figure 1 As shown, it has 6 feeders, and the neutral point of the Z-shaped transformer is grounded through the series resistance of the arc suppression coil. overhead feeder L 1 =15km, L 3 =18km, L 5 =30km, wire-cable hybrid feeder L 4 =17km, the overhead feeder is 12km, the cable is 5km, and the cable feeder is L 2 =6km, L 6 =8km. Among them, the overhead feeder is JS1 pole type, LGJ-70 type conductor, the span is 80m, and the cable feeder is YJV23-35 / 95 type cable. G in the power grid is an infinite power supply; T is the main transformer with a transformation ratio of 110 kV / 35kV, and the connection group is Y N / d11;T Z Is a zigzag transformer; L is the arc suppression coil; R is the damping resistance of the arc suppression coil. The feeder adopts three types of lines: overhead line, overhead line-cable hybrid line and cable line. The load uses ...

Embodiment 2

[0044] Embodiment 2: Using the model in Embodiment 1, the distance feeder L 2 An AG single-phase ground fault occurs 3 kilometers from the beginning, the ground resistance is 50Ω, the initial phase angle of the fault is 90°, and the sampling frequency is 10kHz. fault feeder L 2 and sound feeder L 4 The zero-sequence current waveform of Figure 4 shown.

[0045] Using the same method as in Example 1, select the transient zero-sequence current data 5 ms after the fault and use db10 to perform three-layer wavelet packet decomposition and reconstruction to obtain the time-frequency eigenvectors of each feeder and time-frequency feature similarity matrix , forming a comprehensive correlation coefficient matrix P ij :

[0046] P ij= ; ; ;

[0047] P 1i =[0.0613 172.1959 0.3280 0.4804 10.5826 126.1762]; ;

[0048] The top three with the largest comprehensive correlation coefficients in order of size are: P 2 =172.1959, P 6 =126.1762, P 5 =10.58...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

The invention relates to a power distribution network fault circuit selection method based on transient zero-sequence current time-frequency characteristic vectors, and belongs to the technical field of power system relay protection. When a power distribution network runs into a single-phase earth fault via an arc suppression coil grounding system, a transient zero-sequence current component detected by a measuring end is a nonlinear non-stationary signal formed by different frequency components. By taking the fault component as a study object, time-frequency characteristics of a fault transient current of the fault component are analyzed by utilizing the wavelet packet theory, time-frequency distribution regularities among all feeder lines under different fault conditions are described according to similarity of the time-frequency characteristics, and consequently line selection criteria based on transient zero-sequence current time-frequency characteristics can be obtained. The method is simple in principle, only utilizes short-time window zero-sequence current data of 5ms after the fault, can identify faulty feeders under the conditions of small fault angle and high resistance ground fault, has excellent timeliness and robustness, is free from influence of an arc fault or a resistance ground fault, requires a low sampling rate for hardware, and is highly practical.

Description

technical field [0001] The invention relates to the technical field of power system relay protection, which is based on the time-frequency feature vector of transient zero-sequence current, uses the wavelet packet theory to analyze the time-frequency feature of the time-frequency fault transient current, and uses the time-frequency feature similarity to describe different According to the time-frequency distribution law of each feeder under the fault condition, a new fault line selection method of distribution network based on the line selection criterion based on the time-frequency characteristics of transient zero-sequence current is obtained. Background technique [0002] When a single-phase ground fault occurs in a distribution network whose neutral point is grounded through an arc-suppression coil, the fault transient current amplitude is much larger than the steady-state current and is not affected by the arc-suppression coil. Compared with the steady-state component, ...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08
Inventor 束洪春黄文珍董俊段锐敏朱梦梦高利
Owner KUNMING UNIV OF SCI & TECH
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Patsnap Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Patsnap Eureka Blog
Learn More
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic, Popular Technical Reports.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap|About US| Contact US: help@patsnap.com