Research On Household Energy Router And Its Control Strategy

With the continued growth of the world's energy demand,the discrepancy between energy supply and demand has gradually deteriorated,new energy sources have been developed.Whereas the structure and operation mode of the traditional power system inevitably change when a large number of distributed energy sources connected it.The energy internet technology came into being.As a key node of the energy internet architecture,the energy router is the core equipment to realize energy interconnection and adapt to energy transformation.It is great significance for the transformation and upgrading of the power grid in the future because the energy router has functions such as energy control,information processing,personalized energy use,etc.However,common household energy router has some defects,such as poor DC bus voltage stability and excessive current distortion when energy flows in the opposite direction and so on,such that the power grid is polluted.Therefore,for the household energy router and its core device solid-state transformer,this paper focuses on the solid-state transformer topology,the control strategy of the rectification stage,the intermediate stage,and the inverter stage.Finally,energy positive the waveforms of the output voltage and current of the household energy device are obtained by the cascade simulation of the three-level circuit,which verifies the superiority of the control and the rationality of the design of the topology of the household energy router.The contributions are as follows:(1)The topology of solid-state transformers of household energy routers.Based on the three-level circuit structure of the solid-state transformer,the overall topology of it is designed by determining the single-phase full-bridge PWM rectifier circuit,the dual active bridge circuit,and the single-phase inverter circuit,respectively.Then the schematic diagram of the household energy router is provided.Finally,the mathematical model of the three-level circuit is established.(2)Fuzzy adaptive control strategy for solid-state transformer rectification stage.Since the output voltage is not stable,the larger voltage fluctuation is produced when load change in the traditional control strategy,the idea of fuzzy control is introduced to deal with these problems in this paper,as a result,a fuzzy adaptive control strategy based on double closed loop control is proposed,which not only advances the voltage response speed of single-phase PWM rectifier,but also reduces the fluctuation of output voltage when the load fluctuates,at the same time,the rectifier and inverter can work under unit power factor.The control strategy satisfies the requirements of the two-way energy transmission of the household energy router.(3)Single phase shift control strategy for the intermediate stage of solid state transformer based on voltage single loop.By analyzing the characteristics of the single-phase shift control and the transfer function of the intermediate stage from input to output and from control to output,single-phase shift closed-loop control for the single-phase voltage is proposed such that the intermediate circuit energy flows in two directions.(4)The dq decoupling control strategy for the solid-state transformer inverter stage based on the virtual coordinate transformation.For the problem of steady-state error of PI control in the system of the inverter stage,dq decoupling control based on virtual coordinate transformation is used by inspiring the control method of the three-phase circuit,and the vectors relationship of the rotating coordinate systems in the inverter stage is given to reduce the steady-state error of the system.Finally,a simulation model of the home energy router is built,through a cascaded three-level circuit,the waveforms of energy flow in the forward and reverses of the output voltage and current of the household energy device is shown to verify the superiority of the proposed method.