Method for selectively clearing single-phase ground fault of ship shore power system

Abstract

The invention discloses a method for selectively clearing a single-phase ground fault of a ship shore power system. A variable reactor is arranged between a system neutral point and the ground. When the system is in a single-phase ground fault, the occurrence of the single-phase ground fault is judged according to the rise of a neutral point voltage to ground after the ship shore power system is in a single-phase ground fault; after the single-phase ground fault occurs, the variable reactor is controlled to act within the range of a time angle phi 0 in one cyclic wave of the changes of the neutral point voltage to ground, thus the variable reactor is controlled to gradually decrease a reactance value, and an instaneous tripping mechanism of a corresponding circuit breaker is triggered by gradually increasing short-circuit current so as to clear the fault, wherein the ranges of the time angle phi 0 are as follows: phi 0 is not smaller than 0 DEG and not larger than 50 DEG, phi 0 is not smaller than 105 DEG and not larger than 230 DEG, and phi 0 is not smaller than 285 DEG and not larger than 360 DEG; and before the circuit is completely disconnected, a fuse connected with a corresponding position of the variable reactor is fused, so that the system is restored to a low-current grounding state and the ablation of a contact of a circuit breaker is avoided.

Description

technical field [0001] The invention relates to a method for selectively removing a single-phase grounding fault of a power supply device, which is mainly used in a ship shore power system, and can selectively and quickly remove the fault when a single-phase grounding fault occurs in the system. technical background [0002] The ship's AC power supply system usually adopts a three-phase three-wire IT system with high power supply continuity, but a step-down transformer is required to obtain a single-phase 220V power supply, which increases construction and maintenance costs. The three-phase four-wire direct grounding system can obtain a single-phase 220V power supply without a step-down transformer, which is economical. Due to the large load of single-phase power consumption in ports and wharves, most of them adopt three-phase four-wire direct grounding system, which has a small investment, but the continuity of power supply is not high. When the ship is docked, if the shor...

AI Technical Summary

Problems solved by technology

[0004] However, after a ground fault occurs in the system, if the action time of the varactor is not controlled, the circuit breaker will malfunction or fail to operate.

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