Improving Proportional-Resonant Controller for Unbalanced Voltage and Frequency Variation Grid

The proportional-resonant (PR) controller has been implemented into a power converter to regulate the injected currents in the grid-connected applications. The PR controller has infinite gain at the resonant frequency and thus is able to track a sinusoidal reference signal at the stationary frame. This feature makes the current controllers for the power converter is much simpler in comparison to the PI regulator in synchronous frame. One issue with the PR controller, however, is its dependency on the frequency. The controller cannot track the reference under frequency variation conditions. This paper aims to introduce an improvement in the PR configuration. The derivation of feedback current is taking account and it improves the controller robustness under frequency changes. The simulation results show that the proposed configuration has better performance in comparison the conventional PR controller since it can effectively track the reference signal under frequency deviation.