A Method of Improving the Accuracy of Line Selection for Small Current Grounding Fault

Abstract

The invention discloses a method for improving small-current grounding fault line-selection accuracy. With the method adopted, the problem of low line-selection accuracy caused by small electric faultquantity of a steady-state line selection method using steady-state quantity can be solved; after a single-phase grounding fault occurs on a small-current grounding system, a fault current steady-state component can be increased significantly when a bus-bar sectioning circuit breaker is closed, and therefore, the sensitivity of steady-state quantity-based line selection and positioning protectioncan be improved, and reliable line selection and positioning can be realized. A bus-bar of a protected power distribution system is provided; the bus-bar is of a single-bus-bar sectionalized structure; a circuit breaker is adopted as a bus-bar sectioning switch; the circuit breaker is connected with a measurement and control device; the measurement and control device is connected with a voltage transformer; the voltage transformer is connected with the bus-bar; and the measurement and control device detects whether a single-phase grounding fault occurs on the small-current grounding system and controls the connection of two bus-bar sections through the circuit breaker, so that grounding current can be boosted.

Description

technical field [0001] The invention relates to a ground fault detection technology in a power system, in particular to a method for improving the accuracy of line selection for small current ground faults. Background technique [0002] In the power system, the commonly used neutral point grounding methods mainly include: neutral point non-grounding method, neutral point grounding method through arc suppression coil and neutral point direct grounding method. The first two grounding methods are small current grounding methods. [0003] my country's 6-35kV distribution network mainly adopts the low-current grounding method. In the small-current grounding system fault, the single-phase grounding fault has the highest probability of occurrence. According to statistics, more than 80% of the faults in the distribution network are single-phase grounding faults. When a single-phase ground fault occurs, the power supply system can still ensure that the line voltage is symmetrical, be...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to solve the problem that the accuracy of line selection is low due to the small amount of electrical faults in the current steady-state line selection method based on fault steady-state quantities, and provides a method for improving the accuracy of line selection for small current grounding faults. 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-mentioned circuit breaker is in the closed state before, and after a fault, the measurement and control device will first disconnect it and then close it

Images