Injection current two-point calculation method during small-current grounding fault active arc extinguishing

Abstract

The invention discloses an injection current two-point calculation method employing active inverter to control a fault phase voltage to be zero after a small-current grounding fault. The method can calculate the transitional resistance of a fault point and the injection current, which enables the fault phase voltage to be zero, according a fault phase power voltage, two different injection currents and corresponding bus zero sequence voltages. The method can adapt to the dynamic change of a line structure, is high in precision when the transitional resistance is larger, and solves a problem that a conventional active arc-distinguishing technology (active compensation technology or flexible grounding technology) cannot reflect the dynamic change of the line structure in real time during the calculation of the injection current.

Description

technical field [0001] The invention belongs to the technical field of small current grounding fault self-healing in power systems, relates to the field of arc suppression technology based on active inverters during small current grounding faults, and in particular relates to a method for calculating injected current with active arc suppression technology. Background technique [0002] At this stage, the medium-voltage distribution network in my country widely adopts the low-current grounding method, that is, the neutral point is not grounded and the neutral point is grounded through the arc suppression coil. When a single-phase ground fault occurs, the current at the fault point is small, which is called small current. grounding system. Single-phase ground fault is the main form of distribution network faults, accounting for about 80% of the total faults. When a single-phase ground fault occurs, since the voltage of the three-phase line remains basically unchanged and the c...

AI Technical Summary

Problems solved by technology

However, the existing active arc suppression control methods measure the ground admittance of the system before the fault, and measure the impedance of the neutral point of the system after the fault to calculate the injected current

In the 2 hours allowed to operate with faults after the small current grounding fault occurs, the distribution network line may be switched. At this time, the existing active arc suppression control method is used to calculate and inject the injected current. ground capacitance current, the current at the fault point may still be large

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