A small current grounding line selection method with enhanced fault characteristics

Abstract

The invention discloses a fault feature enhanced small current grounding line section method, which solves the problem of low line selection accuracy due to small electric fault quantity of the existing steady state line selection method using the fault steady state quantity. After a small current grounding system generates single phase grounding fault, the fault current steady state component isobviously increased when a bus section breaker is switched off or a capacitor switching switch is switched off, so that the sensitivity of the line selection and positioning protection based on the fault steady state quantity is improved; the goal of reliable line section and positioning is achieved. A device structurally comprises a bus of a protected power distribution system, wherein a capacitor infeed device is arranged on the bus; a bus section switch uses a breaker; the capacitor infeed device, the breaker and a test control device are connected; the test control device is connected witha voltage transformer; the voltage transformer is connected with the bus; the test control device detects whether the small current grounding system generates the single phase grounding fault or not,and realizes the infeed on the grounding current through controlling the state of a capacitor and the breaker.

Description

technical field [0001] The invention relates to a grounding fault detection technology in a power system, in particular to a small current grounding line selection method for enhancing fault characteristics. Background technique [0002] At present, my country's 6-35kV distribution network mainly adopts the small current grounding method. In the small current grounding system fault, single-phase grounding fault has the highest probability of occurrence, so single-phase grounding fault line selection is still a major problem in relay protection. [0003] After years of research, a variety of line selection criteria have been published and put into field use, but most line selection principles are based on small fault characteristic quantities as the criterion, and the accuracy of line selection is not high in high transition resistance faults. At present, there are mainly four types of line selection principles for small current ground faults: one is the line selection princ...

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that the current steady-state line selection method based on the fault steady-state quantity has a small amount of electrical faults resulting in low line selection accuracy, and provides a small-current grounding line selection method that enhances fault characteristics. When a single-phase ground fault occurs in a small current grounding system, if the bus section circuit breaker (the circuit breakers mentioned in this article refer to the bus section circuit breaker) is in the open state before the fault, it will be closed by the measurement and control device after the fault; The above circuit breaker is in the closed state, and the capacitor switching switch is closed by the measurement and control device after a fault

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