Low-current grounding fault manual discrimination line selection system of power system

Abstract

The invention provides a low-current grounding fault manual discrimination line selection system of a power system and relates to a transformer substation outgoing line grounding fault searching method. The low-current grounding fault manual discrimination line selection system is characterized in that scheduling and monitoring personnel make a comparison according to grounding fault signals and zero-sequence current changing curves of incoming and outgoing lines in a monitoring interface and zero-sequence current value changes, and which incoming and outgoing lines have grounding fault is judged comprehensively through manual work. The method is suitable for county and municipal level power systems, wherein in the county and municipal level power systems, regulating and controlling integration systems are built, unattended operation of transformer substations is achieved, and all incoming and outgoing lines of the transformer substations can collect that 10-35kV neutral points of a zero-sequence current are not in ground connection and are connected with the ground through arc suppression coils and achieve high-resistance ground connection in a county and municipal level power system.

Description

technical field [0001] The manual identification and line selection system for small current grounding faults in power systems relates to a technical field of power insulation fault diagnosis, specifically to a single-phase 10-35kV distribution network with ungrounded neutral point, grounded through arc suppressing coil, and grounded through high impedance The technical field of ground fault discrimination and line selection. Background technique [0002] An ungrounded neutral system has many advantages. Most of the medium-voltage power distribution systems in China use the neutral point ungrounded operation mode. Due to the small ground fault current, the ground current caused by the ground arc is very different, the grounding methods are various, and the length of the substation outgoing line is different. The problem of phase-to-ground fault discrimination and line selection has always been a problem that is difficult to solve completely. From the 1950s to the present, r...

AI Technical Summary

Problems solved by technology

Most of the medium-voltage power distribution systems in my country adopt the operation mode of ungrounded neutral point. Due to the small ground fault current, the ground current caused by the ground arc is very different, the grounding methods are various, and the length of the substation outgoing line is different. The problem of phase-to-ground fault discrimination and line selection has always been a problem that is difficult to solve completely. From the 1950s to the present, relevant manufacturers have used various principles to produce a variety of small-current ground fault line selection devices and put them into use. There are problems such as high threshold value requirements for grounding signals, small application range, working dead zone, components and design and manufacturing defects, resulting in low line selection accuracy, and many line selection devices that have been put into use on site have been withdrawn due to unreliability operation, many new substations simply do not design a small current ground fault line selection device

Under the current design and manufacturing technology conditions, it is difficult to use a specific device or equipment that can be widely used to realize the final and accurate judgment of the ever-changing ground faults

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