轴流转桨式水轮机空化振动监测的试验研究

Experiment investigation of the cavitation vibration detection of Kaplan turbine

为满足电厂水轮机空化监测的需要,本文采用自行设计的空化监测系统对葛洲坝电厂某轴流转桨式水轮机组的现场空化特性进行了试验,通过数据采集和信号分析对多个工况下的水轮机空化信号特征进行了研究。试验中采用4个1-20kHz的高频振动加速度传感器,对水轮机四个不同位置的空化信号进行同时采集。试验表明在同一工作水头,多个工况下,水轮机的空化振动能量主要在2kHz以上,空化振动强度随着机组出力的增加而增大,在水轮机导叶轴和支持盖上所监测到的空化信号特征较尾水管处明显;同时也发现在该试验水头下115MW出力的空化振动能量较110MW和130MW小,是一个理想的工作点。这些结论对电厂的水轮机经济运行具有实际指导意义。

In order to meet the needs of cavitation detection in hydropower plants, a cavitation detection system is devised and an experimental investigation has been carried out to evaluate the cavitation characteristics of Kaplan turbine in Gezhouba hydroponer plant. The investigation is based on the data acquisition and signal processing in muhi-operating conditions. Four high-level accelerometers at frequencies from 1 to 20kHz have been adopted with four channels at the same time, which can improve the precision of data acquisition. In conclusion, the broadband vibration can be detected above 2 kHz under multi-operating conditions at the same net head, the amplitude of the vibration increases as the machine output increases from 30 to 130MW, and the characteristics of cavitation vibration signal are more obvious in the axis of guide vanes and the inner head cover than in the draft tube. But the output power of 115MW is a special operating point, whose vibration amplitude sharply decreases than at output of 110 and 130MW. These results can be a reference for the hydropower economic operation.