Research On Control Strategy Of Energy Router Of Voltage Stabilization Coordination Under Multi Operating Conditions

China’s energy system has gradually changed from fossil energy to green clean renewable energy,but the direct connection of various distributed energy sources to the distribution network will lead to frequent fluctuations in grid voltage,which will seriously cause the collapse of the power system.In order to cope with and solve the above problems,this paper studies a multi-port energy router,which can realize the friendly connection between distributed energy resources and the power grid and reduce the impact on the distribution network through the design of its topology,port control strategy and energy coordination management.First of all,this article selects a multi-port energy router with DC bus architecture,which includes AC interface,photovoltaic interface,energy storage interface,diesel generator interface and DC load interface.A three-phase bridge converter is selected for the AC interface to achieve energy flow between the internal interface of the power grid and the energy router.The DC interface adopts the BUCK-BOOST half-bridge converter to achieve energy flow between various DC interfaces and DC buses.Its working principle and mathematical modeling are analyzed and derived,and the corresponding control strategies are given.The AC interface for the energy router uses Virtual Synchronous Generator Control(VSG).Firstly,by deriving and analyzing the mathematical model of the traditional synchronous generator,the external characteristics of the synchronous generator are introduced into the control structure of the converter,and then the zero pole analysis is carried out according to the derived VSG transfer function,and the influence of the key parameters in VSG on the dynamic performance of the converter is obtained.Considering that under the power grid fault,the negative sequence component will make the traditional VSG unable to operate stably,and the negative sequence component is separated by the instantaneous power of the derivation converter,and an improved VSG is proposed,and the working conditions of the grid voltage single and three-phase fault are set respectively through the Matlab/Simulink simulation platform,and the improved VSG has certain applicability through the active output power fluctuation and the waveform distortion rate of the output current.For the photovoltaic/diesel/storage interface on the DC side,virtual DC motor control(VDCM)is used to increase the rotation of the DC bus,so that the DC bus is injected with inertia and damping.Firstly,the working characteristics and mathematical models of photovoltaic interface,diesel interface and energy storage interface are analyzed.For the photovoltaic interface,the maximum power tracking control(MPPT)and constant voltage control are given.Then,by analyzing the mathematical model of the DC motor,damping and inertia are introduced into the energy storage interface control.According to the derived dynamic transfer function of VDCM,the BODE graph is analyzed to obtain the dynamic influence of key parameters in VDCM on the system.Finally,simulation experiments were carried out by Matlab/Simulink simulation platform,and the light intensity mutation,load mutation and emergency mode were set,and the sag control was compared with the sag control,and the sag control was found to be more suitable for energy storage system than VDCM.Finally,according to the working state of the energy router,as well as the voltage fluctuation and the state of charge(SOC)of the energy storage battery,the working mode is decomposed,and 13 working modes are divided.Coordinated simulation experiments were conducted through the Matlab/Simulink simulation platform.Finally,the experimental verification was completed by experimental prototype.