Research On Power Router Control Strategy Of DC Distribution Network

The DC distribution network has advantages over the AC distribution network in terms of transmission power capacity,system controllability,cost,and power quality.As a node-type unit that constitutes the energy Internet,the electric energy router undertakes the functions of energy flow control and information flow control.The DC power distribution network power router is composed of multi-port conversion units,which flexibly coordinate the input and load of each voltage level.The problem of combined coordinated control of transformation units is one of the core problems of power routers.This paper studies the comprehensive control of power routers in DC distribution networks.The thesis introduces the evolution process of the power router,analyzes the characteristics of various conversion processes,and uses dual active bridge conversion as the main conversion form of the power router studied in this paper,and designs the structure of the power router of the DC distribution network to be studied,based on the DC distribution The nodal control characteristics of electricity,the voltage level and capacity of the electrical energy router are formulated,and the structure and connection form of the related conversion circuit are determined,and the control method of the conversion unit is determined.For the problem of voltage equalization and current sharing of the conversion module in high-power conversion,the voltage equalization control strategy of energybalanced DC-DC converters in series and parallel is studied.In view of the discreteness of the parameters of the modular converter,it is difficult to accurately divide the voltage and current even when the duty ratio of the converter is the same,which leads to the problem that the module that bears a large load is easy to be damaged.The voltage-sharing controller directly controls the energy output balance of each group of converters to ensure the equalization of the input voltage and solve the problem of the equalization of the output current.Aiming at the control problems of DC power routers with multiple voltage levels and complex transformation processes,a comprehensive control method for port energy balance is proposed.Analyze the energy flow of the port,establish the energy model of the DC power router for the port,design a comprehensive controller according to the energy relationship of the port,comprehensively control the energy between the units at all levels,analyze the parameter differences of passive devices in the system The design of the integrated control strategy for the operation of the DC power router connected to the grid to improve the DC bus voltage stability.The Matlab/Simulink platform is used to simulate and verify the comprehensive control strategy and voltage equalization control strategy studied in the paper.The results show that the control strategy proposed in the paper has certain advantages in terms of effectiveness and stability.