Lightning arrester with parallel gap for 110kV transformer neutral point protection

Abstract

The invention discloses a lightning arrester with a parallel gap for 110kV transformer neutral point protection. The lightning arrester comprises a body unit, an auxiliary unit and a parallel gap, oneend of the auxiliary unit is grounded, and the other end of the auxiliary unit is connected with one end of the body unit in series, the other end of the body unit is connected with a to-be-protectedneutral point; the parallel gap is connected in parallel with the auxiliary unit; when a 110kV system is locally out of ground and has a single-phase grounding short-circuit fault or the system operates in a non-full-phase mode, the parallel gap does not discharge, the body unit and the auxiliary unit are connected in series to bear power frequency overvoltage, and the amplitude of the power frequency overvoltage is lower than that of a lightning arrester U1mAd.c. When lightning invades a power station, when the voltage borne by the auxiliary unit is higher than the parallel gap discharge voltage, the parallel gap discharges, the auxiliary unit is bypassed, and at the moment, the overall residual voltage of the lightning arrester is only the residual voltage of the body unit. The overvoltage level of the neutral point of the transformer can be effectively reduced, and insulation is protected against damage; and the safe and reliable operation of the lightning arrester can be ensured.

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 cause the tr...

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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