A Lightning Arrester with Parallel Gap for Neutral Point Protection of 110kv Transformer

Abstract

The invention discloses a lightning arrester with a parallel gap for 110kV transformer neutral point protection, comprising: a body unit, an auxiliary unit and a parallel gap; one end of the auxiliary unit is used for grounding, the other end is connected in series with one end of the body unit, and the body unit The other end is used to connect the neutral point to be protected; the parallel gap is connected in parallel with the auxiliary unit; when the 110kV system partially loses ground and a single-phase ground short circuit fault occurs or the system is not in full-phase operation, the parallel gap does not discharge, and the main unit is connected in series with the auxiliary unit Undertake the power frequency overvoltage, the power frequency overvoltage amplitude is lower than the surge arrester U 1mAd.c. ; When lightning invades the power station, when the voltage borne by the auxiliary unit is higher than the discharge voltage of the parallel gap, the parallel gap discharges, and the auxiliary unit is bypassed. At this time, the overall residual voltage of the arrester is only the residual voltage of the main unit. The invention can not only effectively reduce the overvoltage level of the neutral point of the transformer, protect the insulation from harm, but also ensure the safe and reliable operation of the lightning arrester itself.

Description

technical field [0001] The invention belongs to the technical field of power system overvoltage protection, relates to a lightning arrester, in particular to a lightning arrester with a parallel gap used for the neutral point protection of a 110kV transformer. Background technique [0002] According to the national standard GB / T50064-2014 "Code for Design of Overvoltage Protection and Insulation Coordination of AC Electrical Installations", the AC power system of 110kV and above in my country usually adopts the neutral point direct grounding method. However, under actual system operating conditions, in order to limit the single-phase grounding short-circuit current, most transformers in the 110kV system operate in an ungrounded mode; An overvoltage with a higher magnitude will appear on the neutral point. Since the neutral point of 110kV transformers usually adopts graded insulation, the neutral point insulation level is low, and high-amplitude overvoltage will lead to tran...

AI Technical Summary

Problems solved by technology

[0004] The defects of the current parallel connection of protection gap and arrester include: During operation, due to the inherent characteristics of the protection gap and arrester, there is a blind area of ​​cooperation between the two, resulting in loss of insulation and damage to the neutral point of the transformer in the blind area.

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