Control Of DC Converters For Cooperative Operation Of DC Sources In Flexible DC Power Distribution Systems

The flexible DC power distribution systems have gained much attention and it can improve the quality and capacity of the power,reduce power conversion,renewable energy interfacing and so forth.The flexible DC power distribution systems can supply multiple power with a lot of power electronic DC converters.The active bridge DC converter has been widely used for the equipment of DC distribution because of the advantages of electrical isolation,voltage matching,high efficiency and bidirectional,etc.There are a lot of multiple distributed power sources in the DC power distribution systems.How to realize the coordinated operation between distributed power sources,rationally distribute power and meet the purpose of reliable power supply with control of the DC converter are the focus of this paper.The content of this paper mainly includes the following two points:A novel decentralized control method is proposed which can solve the cooperative operation of multiport low and medium sources.This method is based on series-parallel low-voltage energy storage system.The droop control and the inverse control can realize the coordinated operation and the rational allocation of power of distributed battery energy storage units.The DAB converter of the battery energy storage adopts phase shift control and bias magnetic control.Finally,the stability and effectiveness of proposed decentralized control method can verified by small signal model and simulation.To make the control of different distributed photovoltaic access large-capacity DC bus come true,a three-port active bridge DC converter is selected which simplifies the circuit structure and strengthens the advantages of centralized control.The efficiency can be improved with the single-stage power conversion.In order to realize independent MPPT of PV,a decoupling control method is proposed.This paper uses duty cycle control add phase shift control to meet the principle of volt-second balance and expands the soft switching range.Finally,the feasibility of control strategy is verified by simulation.