交流励磁发电电动机内部故障分析及主保护设计新进展

New Development of Internal Fault Analysis and Main Protection Design of AC Excited Generator-Motor

国内抽水蓄能电站的建设已进入高潮,已在国外广泛应用的转速可调的交流励磁发电电动机也备受关注。丰宁抽水蓄能二期工程准备投产两台300MW可调速交流励磁发电电动机,本文对此机组定子绕组/转子绕组内部故障分析计算的方法以及主保护设计的特点进行归纳总结,为后续变速机组的设计提供了借鉴:交流励磁发电电动机多回路数学模型是交流电机多回路理论的拓展,其正确性已得到实验样机的验证;基于常规水电机组和定速发电电动机主保护设计经验,通过典型故障特征分析来简化丰宁抽水蓄能二期变速机组定子绕组主保护设计;交流励磁发电电动机转子绕组内部短路时产生的分数次谐波磁场会在定子绕组同相分支间产生环流,为变速机组故障率高的转子绕组主保护设计提供了新思路。

The domestic construction of pumped storage power station has reached a climax,and the AC excited generator-motor with adjustable speed,which has been widely used abroad,has also attracted much more attention.Two AC excited generatormotors of 300MW with adjustable speed will be put into operation in the Fengning pumped storage phase II project.For this special kind of generator unit,this paper summarizes the internal fault analysis and calculation methods of its stator winding and rotor winding,furthermore analyzes its characteristics of the main protection design,which provides reference for the subsequent design of variable speed units:the Multi-Loop mathematical model of AC excited generator motor is the expansion of the Multi-Loop theory of AC motor,and its correctness has been verified by the experimental prototype;based on the design experience on main protection of conventional hydropower units and constant speed generator motor,the main protection design on stator winding of Fengning pumped storage phase II variable speed unit is simplified by analyzing the typical fault characteristics;the harmonic magnetic field of fractional order caused by the rotor winding internal short circuit of AC excited generator-motor will generate circulating current between branches in the same phase of the stator winding,which provides a new idea for the main protection design of the rotor winding with high failure rate of variable speed unit.