电动机软起动智能控制系统的应用

青溪水电厂排水系统的水泵控制系统原设计采用旧式常规电动机控制系统，投入运行后多次出现故障，存在许多安全隐患。为确保该系统的安全运行进行了技术改造，以软启动器代替原电动机接触器，以可编程控制器取代常规的继电器，增加了水位信号系统。改造后的排水控制系统具有以下功能：可根据水位和运行要求自动起动、停运排水泵；可根据运行要求灵活切换排水泵的工作方式；提供过载、欠载、缺相和电压不平衡保护；现场显示运行状态，实现智能化监控。改造后系统运行情况良好，消除了输水管道的水锤现象和电动机起动时的冲击电流，减少了电动机的起动电流和检修维护工作量、该项技术还可推广应用于水电厂其它辅机设备或其它领域的自动控制中。

Application of intelligent control system for motor soft start

The drainage system in Qingxi Hydropower Plant originally adopted conventional relay control for its pump control system, which had many hidden troubles and resulted in multiple failures. A resultant modification was conducted, substituting soft starter for original motor contactor, programmable logic controller (PLC) for traditional relay, and adding water level beaconage. The modified drainage control system can automatically start-up/shut-down drainage pump as per water level and operation requirements; flexibly shift working modes of drainage pump as demanded; provide protection against overload, underload, open phase and voltage imbalance; display operation status on site and realize intelligent supervisory control. The modification removes water hammer phenomena in the conduit and surge current during motor startup, lowers motor startup current and saves maintenance labor. The proposed technique can also be spread to other auxiliary apparatus in hydropower plants or other fields of autocontrol.