A hybrid control approach to improve power quality in microgrid systems

Power quality (PQ) in distributed energy resources (DERs) is paramount for maintaining a stable and efficient electricity supply. The consistency and cleanliness of power are integral to ensuring reliability, sustainability, and optimal performance, thereby supporting a resilient and eco-friendly energy infrastructure. This paper introduces a hybrid control method designed to address two significant challenges in microgrid (MG) applications: active resonance damping (ARD) and unbalanced voltage compensation (UVC). Furthermore, the proposed hybrid method combines effective ARD with UVC at MG terminals. The active damping technique employs an external control level to counteract undesirable resonant harmonics, overcoming control bandwidth limitations. This approach offers simplicity in setup and performance without requiring additional system parameter adjustments. For UVC, the suggested control technique estimates the compensation reference using the dual d-q control, reducing the complexity and cost associated with load current measurement issues. The hybrid method integrates the resonant damping signal and the MG negative sequence reference (NSR) voltage, which are fed into a two-level sine-pulse width modulation block (SPWM) to control the MG converter. Simulation results validate the robustness of the proposed combined method in simultaneously compensating for unbalanced voltage and active resonance.

Graphical abstract