The operation of the Beijing power grid is divided into zones,and the grounding method used at the hub station has a significant impact on the overall operation of the electrical grid.In the K zone,the A substation adopts the operating mode of grounding the medium-voltage side neutral point of the 220 kV transformer through a small reactance.This article analyzes the neutral point grounding situation of the main transformer in this zone and the equivalent network of the A substation.It also calculates the short-circuit capacity of the A substation and the single-phase short-circuit current when different main transformers are operated in parallel.The calculation shows that grounding the neutral point through a small reactance can reduce the single-phase short-circuit current and meet the requirements for equipment thermal stability.The article also proposes the operational and switching requirements when the neutral point small reactance is put into operation.
关键词
电网/中性点接地方式/变压器等值网络分析/短路电流计算
Key words
power grid/neutral point grounding method/transformer equivalence network analysis/short-circuit current calculation
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