Unusual pressure rise during the load rejection at a Deriaz turbine

29th IAHR Symposium on Hydraulic Machinery and Systems

Kikuta, H.^1 ; Shimokawa, K.^1 ; Izutsu, K.^1 ; Tsukamoto, T.^1 ; Nakamura, S.^1

Voith Fuji Hydro K.K., Tanabeshinden, Kawasaki-ku, Kawasaki

210-9830, Japan^1

关键词: Commissioning test;    Guide vane openings;    High frequency HF;    Hydropower stations;    Load rejections;    Maximum pressure;    Pressure fluctuation;    Water hammer pressure;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/240/2/022058/pdf
DOI  :  10.1088/1755-1315/240/2/022058

来源: IOP

【 摘 要 】

From the power generation optimization point of view, a type of Deriaz turbine was selected for the Y Hydropower Station in Japan, with the maximum net head of 60.7m and the rated output of 6.3MW. During the commissioning tests of the load rejection, unusual pressure rise waveforms were observed in the oscilloscope. The high frequency pressure fluctuations with large amplitude appeared on the water hammer pressure waveform. In most cases, the maximum pressure rise occurred at the peak of the pressure fluctuations and was close the guarantee. To mitigate the pressure fluctuation and have enough margins to the guarantee of the pressure rise, we tried various closing laws of the runner blade and guide vane and the aeration valve on and off. It is concluded that the pressure fluctuation was related to the developed swirl in the draft tube and there were two key factors to effectively mitigate the amplitude level at site. The one is to keep the closing law close to the on-cam relation during the load rejection. The second is to bring the guide vane opening as small as possible before the pressure fluctuations start, yet we have to take the balance with the water hammer pressure rise.