高坝洲电站机组冷却水流量频繁越限报警分析

Analysis of Abnormal Alarm for Excessive Flow of Unit Cooling Water in Gaobazhou Hydropower Station

高坝州水电站机组在开机、停机状态下多次出现冷却水流量越限报警,且报警频繁,经过对流量计的工作性能与工作状况等进行深入分析研判发现,流量计测量管对外来振动非常敏感,且安装区振动源的振动频率会影响流量计测量管的振动频率,引起流量计的异常振动和零点漂移,造成计量误差。高坝洲电站的水导冷却水流量计安装在水轮机顶盖上方,机组开机时会产生很大的振动,尤其是开、停机过程中,振动更大。此外,管道内壁及探头附着物、尾水波动也是造成高坝洲电厂流量计出现问题的原因。经过采取相应措施,冷却水流量越限频繁报警情况明显好转。

During the startup and shutdown processes of generator units in Gaobazhou Hydropower Station,abnormal frequent alarms are encountered for excessive flow of the unit cooling water. An in-depth analysis on the working performance and conditions of the flowmeter is carried out. It shows that the flowmeter measuring tube is very sensitive to external vibrations. The vibration frequency of the external vibration sources could affect the vibration frequency of the flowmeter measuring tube,which will lead to abnormal vibration and zero drift of the flowmeter measuring tube and finally cause measurement errors. In Gaobazhou Hydropower Station,the cooling water flowmeter is installed above the upper case of the unit. While the unit startup and shutdown processes will generate large vibrations. In addition,the problem could be also caused by the attachments on the internal surface of the tube and the probe,and the fluctuation of the tail water. Corresponding treatment measures are then applied. The abnormal alarm problem is now obviously improved.