Small current ground fault location method based on transient reactive power direction

Abstract

A small current neutral grounding fault location method based on the direction of transient state reactive power is characterized in that change of voltage or current serves as a failure starting condition, and after the starting, the zero sequence voltage is taken as the participating voltage if a detection point can be used for detecting the zero sequence voltage and if not, the following steps are performed: 1, confirming the fault phase as per characteristics of three transient state line voltages, and 2, confirming the transient state line voltage including the fault message as per the type of the fault phase, taking the transient state line voltage as the participating voltage, confirming the characteristic frequency range, and further building a digital filter to filter the participating voltage and the zero sequence current signal, so as to obtain the component within the characteristic frequency range; and then confirming the direction of the reactive power of all the detection points through utilizing the components of participating voltage and the zero sequence current within the characteristic frequency range, so as to further confirm the fault section. According to the invention, the transient voltage and current signals as well as zero sequence voltage and line voltage are utilized at the same time, the positioning reliability is higher, the adaptability is stronger, quick direction protection for ground fault of all the voltage classes is applicable at the same time, and the protection speed and reliability are taken into consideration.

Description

technical field [0001] The invention relates to a small-current ground fault location method, in particular to a small-current ground fault location method based on the direction of transient reactive power, which is applicable to a single-phase ground fault transient location method of a neutral point non-effectively grounded power grid. Background technique [0002] The distribution network is densely covered in urban, rural and mountainous areas, and is outdoors all year round. It is affected by harsh environments such as wind, rain, frost, lightning, and increasingly severe environmental pollution. Coupled with unpredictable human factors, the probability of failure is high, especially for overhead lines. At present, my country's distribution network mostly adopts the operation mode of ungrounded neutral point and grounded through arc suppression coil. After a ground fault occurs, the faulty line can be selected by using the existing line selection device. However, since ...

AI Technical Summary

Problems solved by technology

This method has been applied to a certain extent, but it has the following disadvantages: when the grounding resistance is large, the distributed capacitance on the line will shunt the injected signal, reducing the detection sensitivity and reliability; it is necessary to design a dedicated large reactive power signal generator, hardware High cost; and cannot detect momentary ground faults

In the distribution automation system, the master station is used to realize the time synchronization of each detection device, and the time synchronization error is at least a few milliseconds, which cannot be applied to the method of comparing the instantaneous value of the transient zero-sequence current

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