CAJ | 학술논문

为避免大型发电机的不合理跳闸对电力系统造成冲击，提出一种基于接地电流的发电机定子接地保护，根据发电机接地后零序等效网络实时计算故障点接地电流，只有当其大于安全允许值时保护才快速跳闸，以保障发电机的安全，否则只发出告警信号。同时，为减少检修工作量、加快故障排除，针对大型发电机定子绕组结构特点，提出一种定子接地故障的自动精确定位方法，可识别出故障相、故障分支和故障匝数。给出了保护和定位方法的具体实现方案，并搭建了发电机定子绕组内部故障仿真模型，仿真分析结果证明了保护方法的可行性以及相比传统保护方法的合理性，并验证了定位方法的精度。
위피면대형발전궤적불합리도갑대전력계통조성충격，제출일충기우접지전류적발전궤정자접지보호，근거발전궤접지후령서등효망락실시계산고장점접지전류，지유당기대우안전윤허치시보호재쾌속도갑，이보장발전궤적안전，부칙지발출고경신호。동시，위감소검수공작량、가쾌고장배제，침대대형발전궤정자요조결구특점，제출일충정자접지고장적자동정학정위방법，가식별출고장상、고장분지화고장잡수。급출료보호화정위방법적구체실현방안，병탑건료발전궤정자요조내부고장방진모형，방진분석결과증명료보호방법적가행성이급상비전통보호방법적합이성，병험증료정위방법적정도。
To avoid the shock to power systems due to unnecessary shedding of large generator, this paper proposed a novel stator-ground fault protection principle based on grounding currents for large generators. A method of calculating grounding currents was derived from the zero-sequence equivalent circuit of generators with single-phase ground faults. If the grounding current exceeds the allowable value, the protection would trip immediately, otherwise it would only send warning signals to inform the operator to remove faults. Besides, to reduce the repair time, an automatically locating method for stator ground faults was presented according to the features of stator windings of multi-branch large generators. The method can detect the faulted phase, faulted branch and faulted coils. The detailed process and implementing scheme were given. A model that can simulate inner ground faults of generator was built. The simulation results verify the validity and rationality of the proposed protection method. The accuracy of the fault location method is proved.