Flexible composite arc extinction method for grounding fault of power distribution network adaptive to structure and load changes

Abstract

The invention relates to a flexible composite arc extinction method for a grounding fault of a power distribution network adapting to structure and load changes. A single-phase cascaded H-bridge converter is used as an arc extinguishing device and is hung between a neutral point of a grounding transformer and the ground. Through a parallel voltage and current double closed-loop control method, the zero sequence voltage of the system is regulated and controlled to be a fault phase power supply voltage negative value, and meanwhile, the fault phase current of a fault feeder line is regulated and controlled to be equal to the fault phase load current of the fault feeder line. According to the characteristic that the load current of the fault feeder is the same as the positive sequence component in the three-phase current, the calculation method of the fault phase load current of the fault feeder is provided. The positive-sequence component in the three-phase current of the fault feeder line is extracted in real time by using coordinate transformation and a filter, and then the fault phase load current of the fault feeder line is obtained through coordinate inverse transformation. The problem that an existing flexible arc extinction method is greatly influenced by line impedance voltage drop, ground parameter measurement precision and load current change is solved.

Description

technical field [0001] The invention belongs to the technical field of power system operation, maintenance and fault handling, and single-phase grounding fault arc suppression of power grids, in particular to a flexible composite arc suppression method for distribution network grounding faults that adapts to changes in structure and load. Background technique [0002] As the link closest to the electrical load in the power system, the distribution network has complex line structures and harsh operating conditions. Single-phase grounding faults often occur due to tree branches scraping overhead lines, cable damage and discharge, and insulator pollution flashover. Operation in direct grounding mode will cause frequent trips of the line. In order to ensure the reliability of power supply, the direct grounding mode can be changed to non-grounding mode. However, with the expansion of the distribution network, the single-phase ground fault arc cannot be extinguished in time, resul...

AI Technical Summary

Problems solved by technology

The voltage and current closed-loop controllers are not involved in the measurement of ground parameters and play a major role in high-resistance and low-resistance ground faults respectively, which solves the problem that the flexible voltage arc suppression method is greatly affected by line impedance voltage drop and is prone to failure when metallic ground faults occur And the flexible current arc suppression method is greatly affected by the measurement of ground parameters, and the arc suppression effect is poor when the high resistance ground fault occurs.

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