Power distribution network single-phase earth fault current full compensation method and device

Abstract

The invention discloses a power distribution network single-phase earth fault current full compensation method and device, and the method comprises the steps: S1, two terminals at one side of a step-up transformer being connected with two terminals led out from a secondary side of a Z-type grounding transformer, and obtaining a voltage which is opposite to a neutral point voltage of a fault; after the step-up transformer is used for boosting, restraining the fault phase voltage to be below the arc extinguishing voltage; wherein the Z-type grounding transformer is connected to a power distribution network, the tail end of a phase-shifting winding of the Z-type grounding transformer is in star connection to form a neutral point O, wiring terminals are led out from A, B and C phases of the secondary side, and the terminals led out from the secondary side are selectively connected with terminals on the low-voltage side of the boosting transformer. One end of the high-voltage side of the boosting transformer is electrically connected with the neutral point O, and the other end is connected with the ground end. According to the invention, a voltage opposite to the neutral point voltage of the fault phase is generated through the Z-type grounding transformer and the step-up transformer, so that the fault current is suppressed to be 0.

Description

technical field [0001] The invention belongs to the technical field of single-phase ground fault processing of distribution network, and in particular relates to a full compensation method and device for single-phase ground fault current of distribution network. Background technique [0002] The distribution network goes deep into the densely populated areas of user terminals, and its operation mode and environmental conditions are complex and changeable. More than 90% of the faults in the distribution network are single-phase ground faults. Since the distribution network has capacitance and leakage resistance to the ground, the ground fault Fault currents are capacitive currents and resistive leakage currents. In order to limit the ground fault current, the distribution network generally uses methods such as ungrounded, resonant grounded, and resistance grounded to limit the ground fault current. However, with the increase in the capacity of the distribution network and the...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a full compensation method for single-phase ground fault current in distribution network and its device to solve the problem of needing an independent external power supply and high equipment cost in the existing compensation method. The fault current is fully compensated by adding a voltage opposite to the neutral point voltage of the fault, and the added voltage is taken from the distribution network through a transformer, which can be strictly consistent with the phase and amplitude of the three-phase voltage of the distribution network. Set a complex control method to calculate the current injected into the neutral point to control the voltage, and there is no need to add an independent power supply. It can also be used in systems with large capacitance to ground in the distribution network

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