A detection method for ground capacitance current in power network

Abstract

The invention discloses a power network ground capacitance current detection method, comprising the steps of: installing a current type three-phase four-leg inverter bridge on a three-phase circuit; adjusting a service bridge leg to respectively inject detection current into A, B, C three phases to successively measure a neutral point offset voltage; utilizing a phase voltage, injected current and a neutral point offset voltage phasor to calculate split-phase ground capacitance; and calculating split-phase ground capacitance current according to the split-phase ground capacitance. Based on an original method, the power network ground capacitance current detection method utilizes a power electronic device to respectively add detection current with adjustable amplitudes and angles to the A, B, C three phases, measures the neutral point displacement voltages under the three conditions, and calculates split-phase ground capacitance based on a system phase voltage, thereby respectively calculating system the ground capacitance current of each phase of a system. The method has the characteristics of high accuracy, simple test and great safety, does not interrupt power supply for users, and meets actual use requirements.

Description

technical field [0001] The invention relates to a method for detecting a ground-to-ground capacitance current of a power network, which belongs to the technical field of power systems. Background technique [0002] Due to the obvious advantages of reducing loss and improving economy, high-voltage transmission has been widely used at home and abroad. However, the alternating nature of the three-phase AC transmission of electric energy makes a virtual capacitance formed between the line or coil and the earth through a dielectric (air, etc.), and a capacitive current is generated in the line, which increases with the increase of the voltage level and the length of the line. Large, so that the current amplitude and phase at both ends of the line change accordingly. In addition, when the line is grounded, due to the existence of the capacitive current to the ground, the grounding current becomes larger, which may cause the arc to be difficult to extinguish, resulting in damage t...

AI Technical Summary

Problems solved by technology

The bias capacitor used in this method needs to be estimated manually, because the size of the bias capacitor will directly affect the measurement result, so the improper selection of the bias capacitor may cause the result to be inconsistent with the actual

[0005] At present, most of the measurement methods are based on the assumption that the three phase-to-ground capacitances of the system are equal, which sometimes cannot meet the actual requirements of the project.

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