统调动力源系统单相接地故障选线研究

Research on United Adjustment Power Source System Single Phase Ground Fault Line Selection

发电厂辅机统调动力源系统为非工频小电流接地系统,其单相接地故障常规保护装置及工频小电流接地选线装置均无法正确识别。文中分析了统调动力源系统的运行工况,计算了单母线低频率的极端工况下最小接地电容电流数值,据此提出研制非工频小电流接地选线装置的技术要求,并开发出高精度、能够适应系统频率变化的发电机统调动力源接地选线装置。设计了专用的功能及性能模拟测试电路对装置进行检测,结果表明,该装置完全满足设计要求,投运后运行良好,解决了工程难题。

The power plant auxiliary machine united adjustment power source system is non-utility frequency and small current grounding system. Conventional protection device cannot detect single phase grounding fault in the system correctly. Operating conditions of united adjustment power source system is analyzed, and minimum capacitive ground fault current value is calculated in single busbar low frequency operating condition. Based on calculation, technical requirements of non-utility frequency low current grounding fault line selection device is proposed. Then a high precision fault line selection device which adaptive to system frequency changes is developed. A special functionality simulation test circuit is also built to test developed device. The testing resuhs show that proposed device satisfies design requirements, works well after commissioning and solves practical engineering problem.