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Appl. Sci. 2018, 8(11), 2193; https://doi.org/10.3390/app8112193

Internal Mechanism and Improvement Criteria for the Runaway Oscillation Stability of a Pump-Turbine

1
Chongqing Southwest Water Transport Engineering Research Institute, Chongqing Jiaotong University, Chongqing 400016, China
2
China Ship Development and Design Center, Wuhan 430064, China
3
State Key Laboratory of Water Resources and Hydropower Engineering Science, Wuhan University, Wuhan 430072, China
*
Author to whom correspondence should be addressed.
Received: 3 October 2018 / Revised: 31 October 2018 / Accepted: 5 November 2018 / Published: 8 November 2018
(This article belongs to the Special Issue Pumped-Storage Hydropower Plants)
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Abstract

The runaway oscillation process of the pump-turbine in a high head pumped-storage power plant is usually unstable. The root cause of its instability is still unclear. In this paper, its internal mechanism and the improvement method were studied in depth. First, the flow characteristics in a model pump-turbine during the runaway process at four guide-vane openings (GVOs) were investigated by 3D transient numerical simulations. Then, the energy dissipation characteristics of different types of backflow vortex structures (BFVSs) occurring at the runner inlet and their impacts on the runaway stability were investigated by the entropy production theory. The results show that the location change of BFVSs between the hub side and the mid-span of the runner inlet around the no-load point leads to the sharp change in the energy dissipation rate, which makes the slope of dynamic trajectory positive and the runaway oscillation self-excited. If the occurrence of BFVSs at the hub side is suspended, the runaway process will be damped. Finally, the pump-turbine runner was improved to obtain a wider stable operating range. View Full-Text
Keywords: pump-turbine; runaway process; oscillation stability; transient flows; entropy production; pumped-storage power plant pump-turbine; runaway process; oscillation stability; transient flows; entropy production; pumped-storage power plant
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Zhou, Q.; Xia, L.; Zhang, C. Internal Mechanism and Improvement Criteria for the Runaway Oscillation Stability of a Pump-Turbine. Appl. Sci. 2018, 8, 2193.

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