Method and device for determining fault point location of neutral point non-effectively grounded system

Abstract

The invention provides a method and device for determining a fault point location of a neutral point non-effective grounding system. The determination method comprises the following steps that whether or not a line in the neutral point non-effective grounding system has a single-phase grounding fault is determined; if the single-phase grounding fault occurs, a circuit breaker of a control line will close again after a first trip; if the re-closure of the circuit breaker fails, a permanent fault of the line is determined; if the re-closure of the circuit breaker is successful, an instantaneous fault of the line is determined; under the condition that the permanent failure of the line is determined, a control circuit breaker is trips again; the re-closure time of the circuit breaker and the arrival time of reflection waves at the single-phase grounding fault point of the line after the circuit breaker trips again are obtained, and the location of the single-phase grounding fault point of the line is determined according to the re-closure time and the arrival time of the reflected waves. By the technical scheme, the fault type can be determined, and the fault position can be further detected accurately when the fault type is a permanent fault.

Description

Technical field [0001] The present invention relates to the technical field of power systems, in particular to a method for determining the location of a fault point of a neutral point ineffective grounding system and a device for determining the location of a fault point of a neutral point ineffective grounding system. Background technique [0002] At present, the neutral point non-effective grounding system is the main form of the domestic power distribution system. When single-phase grounding occurs in this system, the line voltage remains unchanged, the ground phase voltage decreases, and the non-ground phase voltage increases. At the same time, the system can only pass through The capacitance to the ground forms a loop, and the capacitance to the ground is very large, resulting in a very small fault current, which brings great difficulties to protection and ranging. [0003] When a single-phase grounding fault occurs in a neutral point non-effectively grounded system, it will ...

AI Technical Summary

Problems solved by technology

The bottleneck of distance measurement in the non-effective neutral point grounding system is mainly due to the complex structure of the power distribution system and the grounding method of the neutral point

Firstly, the power supply distance of power distribution lines is short, which requires high distance measurement accuracy; secondly, power distribution systems are mostly radial structures with many line branches, and there are special cases such as overhead-cable hybrid transmission mode and non-transposition. The unique structural characteristics of the line also increase the difficulty of distance measurement; finally, after a single-phase ground fault (accounting for 70%-80% of the total line faults) occurs in the neutral point non-effectively grounded system, because it does not constitute a short circuit circuit, the fault The current is very small, and the fault zero-sequence current is easily submerged in the zero-sequence current generated by the asymmetry of the distribution system line structure, which makes it very difficult to use power frequency single-phase grounding protection and distance measurement

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