Modeling And Control Of DC Microgrid Based On Multi-Port DC/DC Converter

Distributed generation is the main form of renewable energy utilization and an important development direction of smart grids.However,due to the volatility,randomness and poor controllability of renewable energy generation,how to be compatible with the large-scale access of these distributed renewable energy sources has become a huge challenge for the current grid operation and control.The microgrid is to solve the problem of renewable.One of the most effective ways to distribute energy.Compared with the AC microgrid,the DC microgrid is more convenient for distributed power supply access,and there is no problem of synchronization and reactive power flow between power sources,and the controllability and reliability are greatly improved.Therefore,this paper will conduct research on the operational control of DC microgrid.Firstly,the various components of DC microgrid are introduced.The physical models of photovoltaic power generation,energy storage modules and typical DC/DC are analyzed.The module of photovoltaic power generation is simulated and analyzed.The UI under different illumination intensities is obtained.The characteristic curve and the PU characteristic curve verify the instability of photovoltaic power generation.At the same time,a multi-port DC/DC structure is proposed.Compared with typical DC/DC,multi-port DC/DC can link distributed power,energy storage and load to achieve energy intercommunication.Then,for the application requirements of DC microgrid,a multi-port DC/DC topology suitable for DC microgrid is proposed.The working process of the multi-port flyback converter is analyzed in detail,and the parameters of each component of the model are designed.Through simulation,the model can reduce the voltage amplitude at both ends when the switch is turned off,and realize the zero current switch of the switch tube,thereby reducing the switching loss of the switch tube and improving the reliability of the DC.Secondly,the control strategy of photovoltaic system in DC microgrid is analyzed,and three working states of energy storage system under different photovoltaic output power and different load power requirements are introduced.Based on this,a self-compensating droop control strategy is proposed to realize the stable bus voltage of the energy storage system.At the same time,reasonable power distribution can be achieved between each parallel battery pack.Finally,the multi-port DC/DC DC microgrid is verified by simulation.The feasibility of running a control strategy.Finally,the fault classification and analysis of DC microgrid system and DC microgrid multi-port DC/DC are carried out.Simulation of each fault type is made,and the PV branch fault,energy storage system branch fault,DC bus fault and DC microgrid are obtained.Multi-port DC/DC fault response curve for fast detection of fault location and fault type.