Single-phase power conditioning system with slew-rate controlled synchronizer for renewable energy system in microgrid

This paper proposes single-phase power conditioning system which is capable of connecting a microgrid to an utility grid seamlessly through slew-rate control. The power conditioning system is composed of a single-phase phase-locked loop using an inverse Park transformation to detect the grid phase, a phase synchronizer using the slew-rate control, and isolated bidirectional inverter which transfers power among the utility grid, energy storage, and load. The inverter is controlled by the voltage and current controllers for the island and grid-connected operation, respectively. The power conditioning system operates using the inverter controlled by a mode controller according to the microgrid operation mode and state of charge of the energy storage. The stable operation of the power conditioning system was verified in three microgrid operation modes through simulations using the MATLAB/Simulink tool.