Seamless transfer with interactive compensation algorithm for three-phase grid-connected inverter

Abstract

This paper proposes an interactive control algorithm for seamless transfer of three-phase grid-connected converter between grid-tide mode and stand-alone mode. In order to archive a smooth transfer between two modes, the voltage controller and current controller are designed to generate the output voltage reference of PWM with no interrupted transition during islanding operation and grid connected operation. Additionally, a suitable phaselocked loop (PLL) algorithm is posed to obtain the phase angle of grid voltage continuously during operation time even if the utility outages. With the proposed algorithm, the control algorithm guarantees a smooth profile voltage across the local load when the grid is being disconnected or reconnected. In this paper, the simulation and experiment results verify the proposed method.