Numerical simulation of hydraulic transients in pumped storage power station with finite volume method

Abstract:

The second-order finite volume method (FVM) Godunov scheme was adopted to investigate the hydraulic transients in pumped storage power station. Firstly, the governing equations of mathematical model were discretized according to FVM, and the flux was calculated by Riemann solver. Three slope limiters were introduced and compared to avoid spurious oscillations during data reconstruction. The whole characteristic curves of the unit were transformed by using improved Suter approach. The virtual-boundary approach combined with the governing equations of the unit was presented to achieve a unified computation scheme for all the control volumes at internal domain and boundaries. The results calculated by the proposed scheme were compared with those of method of characteristics (MOC) scheme and measured data, and parameter sensitivity was discussed. Results show that when Courant number was equal to 1, the second-order FVM and MOC had the same accuracy; when Courant number was less than 1, the second-order FVM was more accurate and stable than MOC. During load rejection process of pumped storage station, the unit speed calculated by second-order FVM was basically consistent with the measured value and more accurate than that predicted by MOC. For the calculation of hydraulic transients in pumped storage power station, the values of wave speed in pipe sections with different properties should be adjusted to realize MOC simulations, resulting in computation complexity and numerical errors. While FVM is simpler in computation with higher accuracy, which only requires reducing the Courant number. Therefore, the proposed numerical approach is stable and accurate for hydraulic transients.