Improved selective harmonic compensation for single-phase inverters

Described in this paper is the design and implementation of state space current control with harmonic compensation for a single-phase grid-connected inverter using the pole placement method. The control performance of a grid connected inverter is often affected by the grid impedance in the distribution system to which it is connected. Because it offers full controllability, state space control was employed to address grid impedance effects. As a result, system stability and robustness to grid impedance uncertainties, as well as damping to reduce the LC filter resonance can be improved. In order to track the inverter current reference without steady state error, a PR controller was augmented with state space control. Due to the grid voltage distortion, a harmonic compensator was added to suppress the low order current harmonics. Analysis and experimental results demonstrate the effectiveness of the proposed control method.