负序磁场中同步发电机转子绕组匝间短路故障恶化的分析

Deterioration Analysis of Inter-Turn Short Circuit Fault in Synchronous Generator Rotor Windings Under Negative Sequence Magnetic Field

以1台300 MW同步发电机为例,考虑了阻尼系统,在不对称运行条件下,研究了励磁绕组匝间短路后发电机的相关故障特征量,包括励磁电流、励磁绕组的感应电动势、被短路的励磁回路电流以及阻尼绕组电流等。在此基础上研究了负序磁场中励磁短路线圈的匝数、节距以及短路点过渡电阻等因素对励磁短路电流的影响,并粗略地计算了短路点的发热量。研究结果可为发电机经历恶劣工况后的励磁匝间短路故障的维修提供可靠的决策支持。

The rotor windings inter-turn short circuit fault is one of the common faults in turbine generator.When a generator runs in asymmetric condition emerging negative sequence magnetic field,the deterioration rate of inter-turn short circuit fault in rotor windings can be accelerated.In this paper,a 300 MW turbine generator running under asymmetric operation was studied as an example.Considering damping system,the variations of generator fault characteristics after rotor winding inter-turn short circuit were studied,including rotor current,rotor winding induced electromotive force,short circuit loop current and damping current.What’s more,the influences of rotor short circuit coil turns and pitch and short-circuit point transition resistance under negative sequence magnetic field on the rotor short current were studied,also the heating condition of the short circuit point was roughly analyzed.The results provided a reliable decision support for repairing inter-turn short circuit in rotor winding after a generator experienced bad operating conditions.