Research On Key Technologies Of Multi Machine Coordinated Control And Energy Management For Hybrid AC/DC Microgrid With Wind-Solar-Diesel-Storege

With the increasing depletion of fossil energy,the development process of new energy has been promoted,and the construction of hybrid AC/DC microgrid with wind-solar-diesel-storege is conducive to absorbing nearby new energy,improving the utilization rate of new energy and restraining the disturbance caused by new energy to power grid.Hybrid AC/DC microgrid with wind-solar-diesel-storege has many difficulties,such as many internal units,difficult coordination processes and complex system operation conditions.Designing an energy management strategy that can reasonably coordinate the output between various units of microgrid is the key to ensure the stable,reliable and economic operation of the system.This paper has carried out the following work:Firstly,the mathematical model and output characteristics of wind turbine and photovoltaic cell are analyzed,and the maximum power point tracking control strategy and constant voltage control strateg y of wind power generation unit and photovoltaic power generation unit are designed.The modeling and control method of diesel generator are analyzed,which lays a foundation for the research of virtual diesel generator control strategy.The model and char acteristics of battery and supercapacitor are analyzed,and the mathematical model of bidirectional DC/DC converter is deduced,which lays a foundation for the research of hybrid energy storage control strategy in the following paper.Secondly,the parallel active structure is determined as the main circuit structure of hybrid energy storage unit.Aiming at the phenomenon that virtual capacitor parameters in the supercapacitor control strategy has a n influence on the DC bus voltage and the charging and discharging process of supercapacitor,a power frequency division control strategy of hybrid energy storage unit based on fuzzy adaptive virtual capacitor parameter tuning is proposed.The simulation results show that the control strategy can effectively reduc e the fluctuation of DC bus voltage,shorten the time for DC bus voltage to enter the steady state value,and suppress the drop of the supercapacitor in the state of charge when the system is disturbed.This control strategy improves the ability of the sys tem energy management strategy to resist various disturbance to a certain extent.Thirdly,a virtual diesel generator control strategy based on accurate diesel generator mathematical model is proposed to solve the power imbalance phenomenon when AC/DC interconnected converter and diesel generator run in parallel,and the model deduced based on throttle controller motion increment equation is closer to the original throttle controller.The power balance of AC/DC interconnected converter and diesel generator is realized,which solves the problem of power imbalance when they run in parallel,reduces the reserve capacity requirement of AC/DC interconnected converter when dealing with power mutation,and avoids the situation that the system energy management strategy cannot control the normal output of both.The simulation results verify the effectiveness of the virtual diesel generator control strategy designed in this paper.Finally,this paper takes the deviation degree of DC bus voltage and AC bus frequency as the judgment criterion to carry out hierarchical management of the power in the hybrid AC/DC microgrid with wind-solar-diesel-storege.Combined with the function and characteristics of internal units such as wind power generation,photovoltaic power generation,diesel generator and hybrid energy storage,and based on the analysis of the operation modes of the hybrid AC/DC microgrid with windsolar-diesel-storege in different hierarchical area,the energy management strategy of the hybrid AC/DC microgrid with wind-solar-diesel-storege that is suitable for island operation mode is designed.The simulation results verify that the energy management strategy designed in this paper can effectively suppress the disturbance caused by the sudden change of AC/DC load and fluctuation of new energy,and can maintain the power balance between the power consumption side and the power generation side in the microgrid in real time.