Method for automatically resetting grounding protection device of small-current system

Abstract

The invention provides a method for automatically resetting the grounding protection device of a small-current system, which has the function of automatically resetting. The method comprises the following steps: an intelligent controller of a microcomputer judges whether the small-current system is grounded and further judges the grounding phase if the system is grounded; when the system is subjected to a grounding fault, a switching-on instruction is given to a fault-phase circuit breaker, and the fault-phase circuit breaker is rapidly switched on; the fault phase is connected with a grounding grid via a low-impedance current-limiting reactor provided with a secondary coil; then, a system grounding current flowing through the primary coil of the low-impedance current-limiting reactor is detected by a zero-sequence current transformer, and a high-frequency voltage signal generator connected with the secondary coil of the low-impedance current-limiting reactor is put into operation, soa high-frequency voltage and a high-frequency current are injected into the fault phase of the system; the high-frequency impedance of the fault phase of the system can be calculated by the intelligent controller of the microcomputer, so as to obtain the grounding resistance of the faulted return circuit; and the grounding resistance thereof is further compared with that in the normal system to judge whether the grounding fault disappears, if so, an automatic resetting instruction is given, so as to switch off the fault-phase circuit breaker, thereby automatically resetting the device.

Description

technical field [0001] The invention belongs to the technical field of single-phase grounding fault protection of medium and small current systems in electric power systems, and in particular relates to a method for measuring the grounding phase impedance, judging the disappearance of a fault point and allowing the grounding protection device to automatically reset. Background technique [0002] The small current system grounding protection device has been widely promoted and applied in the power system because of its good protection functions such as extinguishing the grounding arc, reducing the induction signal and preventing intermittent grounding overvoltage. However, because the ability of the device to extinguish the grounding arc is too strong, the fault point does not leave traces of arc burns, which brings great difficulties for relevant personnel to find the fault point. Using the method of timing reset, if the fault does not disappear, it will cause the system to ...

AI Technical Summary

Problems solved by technology

However, because the ability of the device to extinguish the grounding arc is too strong, the fault point does not leave traces of arc burns, which brings great difficulties for relevant personnel to find the fault point

Using the method of timing reset, if the fault does not disappear, it will cause the system to lose its protection function instantaneously, and it will also cause frequent actions of the device

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