Weighted control research on seamless transfer for dual-mode three phase inverter in micro-grid

The utility-interactive inverters can operate in grid-connected and islanded mode. The key technology of dual-mode inverter is to achieve the seamless transfer and reduce the impact of current and voltage to load or grid. A practical grid-connected switch is a physical switch and the switching delay exists. The paper analyzes the influence of the switching delay in detail, that is, there is a uncontrollable intermediate state in the transfer process of grid-connected or off-grid, which will cause voltage and current overshoot. This paper presents a voltage and current weighted control strategies without increasing system complexity. The strategy can ensure that the transient transfer is seamless transfer. Simulations based on MATLAB are carried out and the experiments based on a three-phase inverter verify this method feasibility.