Fine Voltage Control Based on Frequency Separation Two-Degrees-of-Freedom Control for Single-Phase Inverter

Abstract

This paper proposes a new control system that facilitates two-degrees-of-freedom (2DOF) control to reduce the output voltage distortion in the self-sustained operation mode of a photovoltaic generation system. The proposed control system is configured by combining the disturbance observer using a notch filter (notch type disturbance observer) and a sinusoidal tracking controller. This configuration of the system facilitates high tracking performance and high disturbance suppression performance. This system is a new frequency-separation-type 2DOF control system that has the complete tracking performance of only the fundamental frequency, and has the desired recovery performance of the other harmonic frequency and the quick inserting load current. The numerical simulation results and experimental results confirm that the proposed control system reduces the output voltage distortion in an effective manner. Furthermore, the proposed control system is highly robust to the changes in the load.