| With the rapid development of society,the energy crisis and environmental pollution are becoming.more and more obvious,which has become a huge obstacle to the sustainable development of society.The microgrid system consisting of wind,photovoltaic and other renewable energy sources have become an important way to solve these problems.However,due to its randomness and volatility,renewable energy such as wind and photovoltaic will bring great harm to the power system in the process of integration into the power grid.Energy storage system can effectively suppress the fluctuation of wind power and improve the utilization of wind power because of its bidirectional throughput capability.According to the performance analysis of energy storage unit,due to its own control response speed and cycle life limitation,there is no single form of energy storage element to meet high power level and large capacity storage,so it needs a variety of forms of energy storage elements to cooperate with each other to give full play to the advantages of all parties,to better achieve the control requirements of smoothing fluctuations.Therefore,based on the research of power optimization control strategy for wind and solar microgrid,this thesis verifies the economic benefits of hybrid energy storage system and the optimal control effect of hybrid energy storage system in different scenarios.Firstly,the mathematical models of wind power generation system and photovoltaic power generation system are established,and on the basis of the mathematical model,the simulation model is established to verify the power generation characteristics.The self-disturbance maximum power control strategy of wind and photovoltaic power generation system is designed,and control effect is verified by simulation model.The double-loop control model of bidirectional AC/DC converter and DC/DC converter is established,and the control effect is verified by Simulink.Secondly,according to the difference of the characteristics of each energy storage unit in the energy storage system,the energy storage unit is divided into energy type energy storage unit and power type energy storage unit.A power type energy storage unit is adopted to absorb high-frequency power,and an energy type energy storage unit is adopted to absorb low-frequency power.A coordinated optimal control strategy based on state of charge is proposed for hybrid energy storage systems with batteries and supercapacitors.Firstly,the power allocation strategy is adjusted according to the charging state of the energy storage unit,and the concept of time variable is introduced,which is used as the control variable to adjust the power allocation.Then,considering the influence of charging state on the performance of energy storage unit,a time variable autonomous controller based on fuzzy control is designed to correct the time variable,and the power control instructions of battery and supercapacitor are obtained by re-distributing the power.Finally,the power instructions are revised to reduce the misalignment through the auxiliary over-charge and over-discharge protection strategy,and the coordinated optimal control among energy storage units is finally completed.Finally,the power optimization control effect of wind-photovoltaic microgrid is verified.Firstly,the active optimization sliding average algorithm is used to decompose the output power of wind-photovoltaic microgrid into grid-connected target variables and fluctuation components.Then,the fluctuation component is input into the hybrid energy storage system,and the power control quantity of the hybrid energy storage system is decomposed into battery power instruction and supercapacitor power instruction by coordinated optimization control algorithm,so that the fluctuation power can be eliminated.Finally,the optimization of output power of wind-photovoltaic microgrid is completed.Establish the life evaluation model of energy storage unit and economic evaluation index as the criterion to measure the quality of energy storage system. |
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