Transient quantity and medium resistance fused small current grounding line selection tripping method and system

Abstract

The invention discloses a transient state quantity and medium resistance fused small current grounding line selection tripping method, and solves the problems of low action accuracy and low reliability of an existing small current grounding line selection device. The line selection technology provided by the invention comprises a logic cooperation process of transient state quantity method line selection during a fault, medium resistance method line selection and wheel switching. After a grounding fault occurs, line selection tripping is carried out by using a transient state quantity method,if the fault disappears after tripping, reclosure is delayed to be put into use, and tripping is accelerated after reclosure reaches a permanent fault. And if the fault does not disappear after tripping by the transient state quantity method or the fault is selected as a bus fault, a medium resistor is switched on for line selection tripping, if the fault disappears after tripping, reclosing is switched on in a delayed manner, and tripping is accelerated after reclosing to a permanent fault. If the fault does not disappear after the medium-resistance method trips, alternate cutting is conducted. According to the small current grounding line selection tripping method provided by the invention, multi-stage cooperation is formed through a transient state quantity method, a medium resistance method and alternate cutting, line selection tripping can be carried out through next-stage time delay when correct line selection tripping cannot be carried out according to a single principle, rapidtripping is ensured when a permanent fault occurs, the risk of cable trench fire caused by a single-phase earth fault arc is reduced, long-time power failure caused by an instantaneous fault is avoided through reclosing, and the power supply reliability is improved.

Description

technical field [0001] The invention belongs to the technical field of single-phase grounding fault processing of distribution network, and in particular relates to a small current grounding line selection tripping method for fusion of transient quantity and medium resistance. Background technique [0002] Small current grounding line selection refers to identifying the faulty line by using information such as voltage and current in the system when a single-phase grounding fault occurs in a small current grounding system (including the neutral point ungrounded system and the neutral point through the arc suppressing coil system) Technology. In the distribution network, compared with the small resistance grounding system, the biggest advantage of the small current grounding system is the higher reliability of power supply. It is generally believed that the small current grounding system can run for 2 hours with a fault when a single-phase ground fault occurs. Therefore, the ...

AI Technical Summary

Problems solved by technology

However, due to the large difference between the transient quantity method and the medium resistance method, the coordination logic of the two methods for line selection and tripping needs to be further studied

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