Research On The Key Technology Of Multi-port Energy Router Adapting To New Energy Access

With the global energy shortage and environmental pollution becoming more and more serious,the development and utilization of new energy has been valued by all countries in the world,therefore,some scholars have proposed the idea of building a global energy internet,which aims to transport and absorb new energy such as solar energy and wind energy.In the power grid,the traditional power frequency transformer is an important device for power conversion,however,it has the disadvantages of large size,etc,in order to overcome the shortcomings above,power electronic transformers came into being.The energy router is a power conversion device developed on the basis of the power electronic transformer topology,and the energy router has become the core equipment for building the energy internet.In order to meet the requirements of energy internet access to new energy and energy storage devices,here it takes multi-port energy router as the main research object,and separately analyzes the topology,working principle,control strategy and prototype design of multi-port energy router.The main research contents are as follows:(1)The three external physical sources of small hydropower,photovoltaic and energy storage devices are mathematically modeled,and the characteristics of three external physical sources are analyzed,which lays a foundation for the selection of multi-port energy router topology.The common topology of energy routers is compared and analyzed.According to the results of comparative analysis and the characteristics of external physical sources,the topology of multi-port energy routers suitable for this topic is selected.The topology has four ports,including the small hydropower input port,the grid-connected port,the photovoltaic port,and the energy storage port.The working principle of the four ports of the multi-port energy router is described.(2)The four ports of the multi-port energy router are mathematically modeled respectively.Based on this,the control strategy for each port is proposed.The control block diagram of each port is given.The effectiveness of the proposed control strategy is verified by simulation.In order to enable the ports of the multi-port energy router to work together,a two-layer control strategy is proposed.The upper layer is a multi-modal coordinated control strategy,and the lower layer is the independent control strategy of the above four ports.The simulation results show that the multi-port energy router can operate in multiple scenarios.And the simulation results show that the proposed two-layer control strategy can effectively control the four ports of the multi-port energy router,so that the DC bus voltage and the output power remain stable.(3)The design scheme of multi-port energy router small prototype is elaborated,including the overall system structure,power sub-module main circuit topology,power sub-module main circuit parameter,control system hardware,communication scheme,phase-locked and synchronous control scheme,current sharing scheme.Among them,the design of control system hardware includes power module,AD sampling module,main controller module,communication module,and fault protection module.Finnally,the simulation of the small prototype is carried out.