Flexible grounding device single-phase grounding fault line selection and arc extinguishing method for power distribution network

Abstract

The invention discloses a flexible grounding device single-phase grounding fault line selection and arc extinguishing method for a power distribution network. The method mainly comprises the steps: employing a virtual resistor control mode when a single-phase grounding fault happens to the power distribution network, controlling a flexible grounding device to inject a resistive current with the controllable amplitude value into a neutral point, enabling a system to operate in a small-resistance grounding mode, and judging a fault feed line through the measurement and comparison of the zero sequence currents of all feed lines, and giving the feedback to a relay protection device; employing a virtual inductance control method, controlling the flexible grounding device to inject an arc-extinguishing compensation current into the neutral point, enabling the system to operate in a resonant grounding mode, and achieving a purpose of single-phase grounding fault arc extinguishing. Through the switching of control modes, the method can solve problems that a resonant grounding system cannot accurately judge the fault feed line, a small-resistance grounding system is high in fault trip-out rate and a fault of a conventional flexible grounding device control method is difficult to detect during high-resistance grounding. The method can reduce the maloperation rate of protection, improves the fault arc extinguishing success rate, and improves the power supply reliability of the power distribution network.

Description

technical field [0001] The invention relates to the application field of single-phase ground fault processing of distribution network, in particular to a line selection and arc suppression method for single-phase ground fault of a flexible ground device of distribution network. Background technique [0002] The distribution network is at the terminal of the power system, has a complex and changeable structure, and is closely connected with users, which easily leads to various faults. Single-phase ground fault is the most common fault in distribution network. When the fault current is too large, arc light will be generated, and arc combustion will bring great harm such as fire and equipment damage. In order to solve the above problems in distribution network, domestic and foreign power distribution The network generally adopts the method of changing the neutral point grounding to limit the ground fault current. It has experienced the development process of ungrounded neutral ...

AI Technical Summary

Problems solved by technology

The neutral point ungrounded system can still run with the fault for 1 to 2 hours after a single-phase ground fault occurs, and the power supply reliability is high, but the insulation of each phase must be based on the phase voltage. Double-fold design, which requires high insulation; the neutral point through the arc suppression coil grounding system can effectively reduce the ground fault current, but the connection of the arc suppression coil will make it difficult to select the fault line; the grounding system through the small resistance grounding fault occurs When the short-circuit current is very large, the relay protection device will act at the moment of the fault to cut off the faulty line, but at the same time it also reduces the power supply reliability of this method

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