水电厂励磁系统PT断线原因分析及处理

摘要

Through judging the possible links where the fault occurs, such as the contact state of measuring circuit outside the regulator, the PT plate components, the contact state of measuring data cable, the load differences of PT secondary side and the regulator PT wire break criterion etc., so as to find out the reasons of false alarm signal due to instantaneous PT wire break of excitation system when starts up the hydropower unit from zero voltage. Finally, it is known that one of the fault reasons is too small DC sampling value resulting from long time delay of DC sampling of PT plate. Namely, a false alarm signal is sent out when a PT wire break criterion is satisfied. To solve this problem, it is required to optimize the RC filter parameters of PT plate. After optimization, the regulator runs normally and no simi-lar false alarm signal is received.%为查找水电厂机组开机零起升压过程中励磁系统出现瞬时PT断线报警的原因,主要从调节器外围测量回路接触情况、PT板件内元件、测量数据线接触情况、PT二次侧负载差异情况及调节器PT断线判据等可能存在问题的环节进行了分析排查,最终确定了故障原因之一是PT板件直流采样值延时时间偏长而导致直流采样值偏小,当满足PT断线判据时误报故障信号,针对此原因提出的处理办法是优化PT板件RC滤波参数,经优化后调节器运行正常,没有再出现同类故障信号.