Study On The Connected Optimal Dispatch Of Wind And Photovoltaic Power Generation Based On Pumped Storage And Photothermal Power Station

Wind and photovoltaic power generations,a new technology of energy power generation with high economic value which can be used widely,have been developed rapidly under the background of promoting energy conservation,emission reduction and the rapid development of clean energy.With the increase in the scale of wind and photovoltaic power generations,the consumption of traditional fossil energy has been reduced effectively and the sustainable development of energy has been realized.However,difficulty in dispatching the power grid has been increased due to the uncontrollable characteristic of the wind and photovoltaics;the traditional dispatching mode of grid operation and dispatching capacity of conventional units haven't met the demands of grid-connected of wind and photovoltaics with large scale.Therefore,the optimal dispatch of the whole system is conducted in this thesis by using pumped storage and photothermal power stations as an energy storage system and conditioning power supply.The main research contents are shown as follows:(1)On the basis of the analyses of the mathematical models and output characteristics of wind and photovoltaic power generations,the further analyses of dispatching and energy storage characteristics are made.Though the simulation analysis,it is found that applying pumped storage and photothermal power station as the energy storage system can balance output power of the wind plant and the photovoltaic power station,so that the output of wind and photovoltaic can meet the demand for grid access.(2)Firstly,aiming at the impact of the uncertainty and randomness of the output of wind and photovoltaics on the grid and the problem of consuming the wind and photovoltaics difficultly,the chance constrained programming method is employed to establish a day-ahead optimal dispatching model of wind and photovoltaic power generations based on the pumped storage and photothermal power station.The first objective function in the model stands for the lowest operational cost that considers not only the operational costs of conventional units,but also the operational costs of wind and photovoltaic power generation,pumped storage station and photothermal power station.The second objective function is the minimum variance of combined system's output power,and it plays the role in enhancing the function of dispatching output of wind and photovoltaics in the pumped storage station and the photothermal power station.Therefore,the stochastic dispatching model is established by bringing in the chance constrained program.Then,the multi-objective function is processed by the method of fuzzy satisfaction,and the technique of stochastic simulation and the improved particle swarm optimization algorithm are used to solve the function.The case study shows that day-ahead optimal dispatching model of wind and photovoltaic power generations based on the pumped storage and photothermal power station can not onlybalance the output of wind and photovoltaic,but also can improve the economy of the combined system.Finally,the rationality and effectiveness of the dispatching model are compared and analyzed through different dispatching scene.(3)Depending on the characteristic that predicted accuracy of the output of wind and photovoltaics and load will increase with the decrease in time-scale,the dispatching mode of wind and photovoltaic power generations in multi-time scale based on pumped storage and photothermal power generation is proposed in this thesis.Firstly,the problems existing in traditional dispatch are introduced.Then,the overall strategy of coordination and dispatch in multi-time scale is established to study the solving steps of the optimal dispatching model in multi-time scale,the mathematical models of rolling dispatch and real-time dispatch are also established by using the method of the chance constrained program at the same time.What's more,through the simulation analysis on the cases of some area in Northwest China,the results of both rolling and real-time dispatches are obtained.And the result of real-time dispatch is analyzed and compared with the result of day-ahead dispatch.The analysis of algorithm case shows that day-ahead dispatch uses day-ahead predicted data with large error to make dispatching plan and day-ahead dispatching plan with large deviation.After carrying out the rolling plan,the deviation is greatly reduced,and the phenomenon of abandoning wind and photovoltaics is alleviated.Finally,through the implementation of real-time dispatching plan,the deviation between the real-time dispatching plan and the real-time plan is rather small.And through the adjustment by the AGC unit,the manual intervention is shaken off basically so that the economy and safety of the connected dispatching system and the accessing rate of wind and photovoltaics are improved greatly,meanwhile,the impact of the volatility and randomness of wind and photovoltaics on the power grid is reduced.