Neutral point protection device of transformer

Abstract

The invention discloses a neutral point protection device of a transformer. The neutral point protection device of the transformer comprises a metal oxide arrester and a ball electrode protection device, wherein the ball electrode protection device at least comprises a first discharge ball gap, a second discharge ball gap and a trigger electrode; the trigger electrode is used for discharging electricity to generate sparks under the action of high pulse voltage; and the electricity is discharged and the sparks are generated between the trigger electrode and the first discharge ball gap or the second discharge ball gap due to the high pulse voltage acting on the trigger electrode, so that the breakdown voltage between the first discharge ball gap and the second discharge ball gap is reduced and/or the ball gap between the first discharge ball gap and the second discharge ball gap is broken down. According to the neutral point protection device of the transformer, a neutral point protection gap of the transformer can reliably act during power frequency overvoltage, and does not act during lightning overvoltage and operation overvoltage, so that insulation of a neutral point of the transformer is protected; the condition that the arrester does not explode due to overlong current passing time is ensured; and the neutral point protection device of the transformer is reasonable in structure, safe, efficient and reliable.

Description

technical field [0001] The invention relates to the field of power transformation engineering, in particular to a transformer neutral point protection device. Background technique [0002] In the prior art, 110 and 220 KV substation systems adopt the method of effectively grounding the neutral point. In order to limit the single-phase grounding short-circuit current, prevent communication interference and the overall configuration of relay protection, etc., the neutral point of some transformers is usually not grounded. run. [0003] At present, lightning overvoltage and power frequency overvoltage with high amplitude are more harmful to transformer neutral point insulation. Existing transformer neutral point protection devices usually use power frequency gap protection, lightning overvoltage, and operating overvoltage protection scheme. However, judging from the current operation situation, the action characteristics of the protection gap are highly dispersed, and the pro...

AI Technical Summary

Problems solved by technology

However, judging from the current operation situation, the action characteristics of the protection gap are highly dispersed, and the probability of malfunction has increased, which affects the reliability of the power grid operation. For example, the zero sequence protection is caused by the malfunction of the protection gap under transient overvoltage The action jumps the main transformer, and the protection gap refuses to move under the power frequency overvoltage, causing the arrester to explode, and causing the neutral point of the transformer to withstand the power frequency overvoltage for a long time, and the insulation safety is threatened

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