Study On Ice Evolution In The Reservoir Area Of Pumped-storage Power Station In Cold Region

China has planned and built a large number of pumped-storage power stations(PSPS)in cold regions.The ice condition in the reservoir area of PSPS is different from that of conventional hydropower stations.It mainly involves with the impact of PSPS operation on ice conditions in reservoir area,calculation of frozen storage capacity under different ice conditions etc.At present,there are relatively few studies on the ice condition in the reservoir area of PSPS,most of which are based on the observation and description of the ice condition in the specific PSPS,while the relevant numerical simulation research is insufficient.Therefore,it is of great significance to systematically study the ice condition evolution in the reservoir area of PSPS in cold regions for ice disaster prevention and control.The research adopts numerical simulation method.Three typical PSPS of Pushi River,Hohhot and Xilongchi were selected as research objects,and the effects of air temperature and water temperature on ice thickness changes were considered.The mathematical model of ice condition in reservoir area of pumped storage power stations in cold regions was established.The model related parameters are preliminarily determined and the model is solved.By compiling the application program of the mathematical model of ice regime in the reservoir area of PSPS,the simulation of ice regime evolution in the reservoir area of PSPS is realized.By analyzing the formation,development and melting process of ice in the reservoir area of PSPS,the following results are obtained:(1)Through numerical simulation of steady-state and unsteady-state ice cover thickening process under hydrostatic conditions,it is found that air temperature has an effect on steady-state ice thickness and ice freezing rate.Under the same negative air temperature,the ice cover thickening rate increases rapidly in the initial stage,then slows down gradually and tends to be stable.The simulation results are in line with the actual situation.(2)Numerical simulation of water temperature field after water filling in reservoir area.During ice freezing period,the intake water in the reservoir area increases the overall water temperature,especially in the area near the intake.The further away from the intake,the weaker the temperature rise effect.The intake flow rate and temperature are the important factors affecting the water temperature distribution.(3)Considering the actual characteristics of the reservoir area of PSPS,three physical calculation areas of the intake area,the reservoir area and the outlet area are constructed.Coupled with three models,including hydraulic calculation model,temperature diffusion model and ice cover thermal fluctuation model,the water-heat-ice process of PSPS is studied.The ice condition in the reservoir area of the PSPS is simulated by combining the grid generation and dynamic boundary treatment technology.The results show that the correlation between air temperature and ice cover,water temperature and ice cover is generally significant.The simulated calculation values of maximum ice cover and frozen storage capacity in the reservoir area are consistent with the measured conditions.(4)Because of the heat transfer caused by water inflow and outflow,the thickening process of the ice cover in the reservoir area of the PSPS is slower than that of the conventional reservoir,and the ice melting duration is relatively short,and the ice thickness distribution is uneven.It is difficult to completely freeze the reservoir area in winter when the PSPS is in normal operation.Thin ice area and open water area are located near the intake.The above research results can provide some reference for the selection of winter operation dispatching mode of PSPS and the reserve of frozen storage capacity.