Research On Joint Optimal Scheduling Of Cascaded Hydro-Wind-Photovoltaic Generation System

Due to the limited exploitable capacity of the primary energy,the power generation on the power supply side can not keep pace with the power demand of the social production,resulting in the decrease of power supply quality,the sharp increase of the peak-valley load difference and the decrease of the load rate in the large regional power grid,during the peak period of power consumption,the phenomenon of switching off and power limiting occurs frequently.The adjustment of energy structure under the sustainable development strategy of energy saving and emission reduction coincides with the reduction of fossil energy shortage and the green concept advocated.This paper makes full use of the adjustability of the surplus water resources and storage capacity of cascade hydropower stations,and combines with large-scale wind and photovoltaic dispatching to improve the clean energy power supply to the grid,and to alleviate the power supply pressure and peak load regulation pressure of the grid,the following studies have been carried out on a cascade hydropower station in Hubei Province and the wind and photovoltaic electric fields nearby:Firstly,in view of the problems faced by cascade hydropower stations,such as "abandoned water and flood protection in flood season,less water and less power generation in dry season" and not being able to maximize the development and utilization of water resources,the medium-and long-term optimal operation strategy of cascade hydropower stations with new hybrid pumped-storage units is proposed.Based on the objective function of maximum annual generation efficiency,the adaptive water level corridor method is used to decouple the constraint conditions of cascade complex relations under the installment price,and a stepwise optimization algorithm is used to solve the model.The simulation results show that the new pumped-storage units can increase the overall generation income of the cascade,decrease the abandoned water in the high-flow years,and increase the electricity in the low-flow periods,thus providing a new idea for maximizing the utilization of water resources and improving the cascade water distribution.Secondly,with the increasing installed capacity of wind and photoelectric fields in the vicinity of cascade hydropower stations,the contradiction between the small area of power supply and the choke point of main transformer has become increasingly prominent,resulting in a large number of wind and photovoltaic problems,the wind-photovoltaic-cascade hydropower stations combined complementary operation model is constructed.Taking the maximum annual generation as the objective function,the step-by-step optimization algorithm is applied to solve the problem.The simulation results show that the wind-photovoltaic is connected into the power grid together with the complementary of hydropower and water power,which guarantees the full absorption of the wind and photovoltaic and gives the support to the hydropower quantity,and improves the problem of less electricity in the dry period of the hydropower output channel.It provides a reference for the cascade water scenery joint operation to improve the clean efficient energy use and the power consumption on the grid in the future.Thirdly,in order to solve the problem of low proportion of peak-shaving power supply and insufficient peak-shaving capacity,a combined peak-shaving strategy of wind-photovoltaic-cascade hydropower stations is introduced,and a short-term dispatching model with the minimum mean square deviation of residual load as the objective function is constructed,an improved particle swarm optimization algorithm with shrinkage factor and homogenization of initial population based on good point set method is presented.The simulation results show that wind-photovoltaic-cascade hydropower stations are combined to regulate the peak load,wind power and photovoltaic power are fully connected to the network,and the residual load mean square error and peak-valley difference are further reduced,the paper provides a reference for the feasibility of the combined peak regulation of cascade hydropower stations and the surrounding wind and photovoltaic electric fields.The improved particle swarm optimization algorithm does not fall into local optimum prematurely,and has better searching precision and convergence speed.