Grid-connected inverter with inner output impedance and governor-free characteristics

This paper proposes for a PWM ac/dc inverter a new control algorithm that provides the inverter with both inner output impedance and governor-free characteristics. The proposed algorithm regulates the inverter as a voltage source all the time in not only standalone but grid-connected operations. The Park's equation of a synchronous machine is realized in a PWM inverter. The inner output impedance and the governor-free characteristics based on the algorithm are analyzed mathematically. The characteristic equations to design the inverter are derived through the analysis. Experimental results show that the measured values and the calculated values get in good agreement. The output voltage and current performance of the proposed inverter is characterized similarly to a synchronous machine without any compulsory control.