Control Strategy of Smooth Switching Between Grid-connected and Off-grid Operation for Multi-port Home Energy Router

Abstract

This paper takes home energy router(ER) as the research object and analyzes the topology of energy router(ER). From an economic point of view, the disturbance observation method is adopted to realize maximum power-point tracking (MPPT) control for the photovoltaic(PV) array. The controller of the energy storage converter and the DC load converter were designed, which can realize the charge and discharge management of the energy storage battery and the stability of the load voltage. Aiming at the problem of switching between grid-connected and off-grid operation modes on the AC side of the ER, design a pre-synchronization controller to realize the synchronization of the inverter output voltage and the grid voltage before switching from off-grid operation to grid- connected operation mode. Based on PQ-U/f control method, considering the problem of controller saturation, adopt a shared current loop controller structure, and use the state-following controller switching method to achieve smooth switching between grid-connected and off-grid operation. Finally, through Matlab/Simulink software simulation, the stability of the system and the feasibility of the control strategy are verified.