500 kV罗平站主变加装中性点限流电抗器电磁暂态研究及设备选型

Electromagnetic Transient Study and Equipment Selection of Neutral Current-limiting Reactor Installation for Main Transformer in 500 kV Luoping Substation

随着电网的发展,部分自耦变压器中压侧电抗常接近于零,导致变压器220 kV侧发生近区单相或两相接地时,故障穿越电流已接近甚至超过变压器可承受短路电流的极限值,为限制罗平站220 kV单相或两相短路电流水平、改善主变运行环境,拟在主变中性点加装限流电抗器。采用最新EMTPE程序,通过对主变接入限流电抗后短路电流水平、过电压及绝缘配合等电磁暂态特性研究,提出了500 kV罗平站主变中性点限流电抗器阻抗选取原则及限流效果、工频及操作过电压水平、流经主变中性点电抗器的工频稳态及暂态电流水平,并确定了主变中性点避雷器及限流电抗器的技术参数。通过改造可显著降低罗平站220 kV单相或两相短路电流水平,有效改善了主变运行工况。

With the development of power system, the medium voltage side of the autotransformer reactance is very close to zero, leading to fault ride through current is close to or even exceed the transformer can withstand short circuit current limit value when nearly single-phase or two-phase grounding transformer 220 kV side, to restrict Luoping Substation 220 kV single phase or two phase short circuit current level, improve the main transformer running envi- ronment, in main transformer neutral point reactor with current limit. Using the latest EMTPE program, the electro- magnetic transient characteristics of the main transformer, such as the level of the main transformer current, overvoh- age, insulation and so on, are studied. It is put forward that the 500 kV main transformer neutral point Luoping Sub- station current-limiting reactor impedance selection principle, current-limiting effect, power frequency and switching overvoltage level, steady state and transient current level on the neutral point reactor of main transformer, the main transformer neutral arrester and current limiting reactor technology parameters are determined. By means of the transformation, it can significantly reduce the level of 220 kV single or two phases short-circuit current in Luoping Substation, and improve the operating condition of the main transformer.