防止紧凑型变压器重瓦斯误动作的仿真研究

Simulation Research for Preventing Malfunction of Heavy Gas in Compact Transformer

为了降低电网暂态冲击引起紧凑型变压器本体重瓦斯误动作概率,通过变电站实际参数建立ATP/EMTP仿真模型,计算不同杆塔绝缘子串闪络形成稳定电弧时的短路电流,精确预测雷击输电线路引起重瓦斯误动作的范围和概率。在此基础上提出加强线路绝缘、在变压器入口前串联小电感和变压器中性点接小电抗等3种限制短路电流的措施,以降低变压器重瓦斯误动。分析所提措施对实际电网的影响,得出可行性方案。分析结果表明,综合运用3种措施对限制短路电流具有显著效果,能有效降低变压器重瓦斯误动概率。

To reduce the malfunction probability of the heavy gas in compact transformer due to the transient impulse from power grid, an ATP/EMTP simulation model is built using actual parameters of a substation to calculate the short-circuit current when flashover on different tower insulator string form stable arc. The short-circuit current is used to accurately predict the range and probability of heavy gas malfunction caused by lightning stroke on transmission line. Consequently, three protection methods, i.e., enhancing the line insulation, connecting small inductors in series before the inlet of transformer, and connecting small reactors at neutral points of transformer, are proposed to restrict short-circuit current and reduce gas malfunction. Moreover, the effects of the proposed methods on actual power grid are analyzed to obtain a feasible scheme. It is shown that integrated usage of the three methods can achieve significant effectiveness in restricting the short-circuit current and reducing the malfunction probability of heavy gas in compact transformer.