Single-phase cable-based voltage phase positioning method

Abstract

The invention discloses a single-phase cable-based voltage phase positioning method. Each power distribution terminal detects a zero-sequence voltage value of a power distribution network, and judgeswhether a single-phase earth fault occurs or not. A traditional zero-sequence current transformer is installed at the wire outlet end of each feeder line of a transformer substation bus, and a zero-sequence current power-frequency signal is sent to a transformer substation detection device through a traditional zero-sequence current transformer secondary circuit. A current monitoring device is used for dynamically monitoring the current of a power distribution network monitoring point. Through comparing the monitored current value with a preset normal current reference value, whether a fault over-current exists or not is judged. The fault over-current crossing values of all monitoring points are collected by a control main station, and then a current alarm information set is formed. The sudden change of the phase voltage of each data acquisition device and the sudden change of the phase current of the data acquisition device are calculated. After that, the zero-sequence voltage and thezero-sequence current collected by each data acquisition device are processed, so that the phase positions of all frequency components of the zero-sequence voltage and the zero-sequence current are obtained. The reference phase of the operation voltage is obtained by shifting the phase of a coupling voltage backwardly at an angle of theta degree.

Description

technical field [0001] The invention relates to the field of electric power, in particular to a voltage phase positioning method based on a single-phase cable. Background technique [0002] In recent years, a large number of cable terminal insulation breakdown and even explosion accidents have occurred in urban power cable lines. The insulation status evaluation of cable terminals has attracted widespread attention and great attention from power system operation and maintenance units. There are still many key issues unsolved in live detection and insulation diagnosis of partial discharge for cable terminals in actual operation, such as the difficulty of obtaining the phase of the operating voltage for partial discharge phase analysis. Extracting the real PD signal through the inherent characteristics of the PD signal is an important problem that must be solved in PD detection. These signal characteristics include the time phase information, time-frequency characteristics, du...

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is to indirectly measure the operating voltage phase of medium-voltage single-phase cable terminals with high reliability. The purpose is to provide a voltage phase positioning method based on single-phase cables for medium-voltage. The positioning method solves the problem of online high-reliability detection of the voltage phase of the high-voltage equipment to be tested