500kV主变单相替换对主保护的影响分析

结合某500kV变电站用原#1主变A相备用变压器替代存在故障的#2主变B相运行的工程实例,基于PSCAD/EMTDC建立了单相三绕组自耦变压器组的模型,对比分析替换前后的稳态和暂态特性,研究变压器单相替换后因三相绕组短路电压百分比不一致对变压器差动保护和瓦斯保护的影响.仿真分析表明该替换对变压器主保护影响不大,可以在不修改定值的情况下继续运行.为500kV变压器单相替换的工程实施提供了技术支撑.

Analysis of impact on 500 kV transformer protection caused by single phase transformer replacement

A example of a faulted single-phase transformer replaced by a new standby transformer in a 500 kV substation was studied in this paper,A special model of single phase three winding autotransformer was established with the PSCAD/EMTDC software,which was used to compare the transformer steady and transient characteristics before and after the replacement.After the replacement,short-circuit voltage percentages of three phase was asymmetry.The impact on differential protection and gas protection was also analyzed.After simulation and analysis,the preliminary conclusion was that the replacement had little impact on main protection of the transformer.The transformer can thus operated without the protection value modified,which provided technical support for further studies on 500 kV single phase transformer replacement.