Abstract
In this study, fast Fourier transform and inverse transform are adopted for noise reduction filtering the data of load rejection pressure of a single unit in a one-tube, four-unit pumped storage power station. Five-spot triple smoothing method is used to extract the time-average and pulsation value of the water hammer pressure of the spiral case and draft tube inlet. The reasonable correction formula is put forward, and the pulsating pressure rise rate of the spiral case (4.44%) and the draft tube inlet (−1.22%) are obtained. A mathematical model is also established for the transition process of the water conveyance and power generation system of the pumped storage power station, and the field single-unit load rejection condition is simulated. The simulation results are consistent with the measurements, and the accuracy of the calculation model in predicting the time-average pressure of water hammer is verified. Thus, the extreme successive load rejection conditions can be simulated based on the proposed model. Combining with the pulsating pressure rise rate of unit, the actual extreme value of extreme working condition is reasonably calculated. The conclusion shows that the pressure of spiral case and draft tube inlet after considering pressure pulsation can meet the control requirements, avoid the damage caused by extreme working condition test to unit, and ensure the operation safety of unit.
Highlights
With the progress of technology, pumped storage power stations have been developing towards the direction of high head, large capacity, and high speed
According to the numerical simulation calculation, the pressure control condition of the spiral case is that four units load rejection at the same time, the maximum pressure occurred in unit 1
For high-head pumped storage power station, the extreme pressure of dangerous working conditions under pressure pulsation cannot be predicted in a better way and checked whether it
Summary
With the progress of technology, pumped storage power stations have been developing towards the direction of high head, large capacity, and high speed. Such high amplitude and unsteady pressure fluctuation will affect the working life of the turbine [3,4] He et al analyzed the transient characteristics of the pump turbine in the start-up process by using the three-dimensional full flow channel numerical simulation method and discussed the relationship among pressure pulsation, mechanical vibration, and the dynamic stress of the runner. In view of the above problems, this paper analysed the on-site pressure data of single-unit load rejection of a certain high-head four-unit pumped storage power station, extracted the mean and pulsation value of the spiral case pressure and the draft tube inlet pressure and defined the pressure correction formula considering the pressure pulsation. The data of field load rejection pressure of the single unit at the station were processed, and the time-averaged and pulsation values of the water hammer pressure of the spiral case and draft tube inlet were extracted. The sixth and seventh parts contain the discussion and conclusion, respectively
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