Advance Controller for Power Quality and Performance Improvement of Grid-Connected Single-Phase Rooftop PVS

This paper proposes a robust controller for a single-phase single-stage photovoltaic systems (PVS) converter connected to the grid. A high efficiency single-phase single-stage converters are prone to double frequency oscillations and DC-link voltage fluctuations when connected to a PVS. It introduces phase shift and injects harmonics in the grid current. To address this issue, a robust DC-link voltage controller is proposed. It can achieve fast transient response with lesser overshoot under power intermittency and grid side disturbances. A filter is employed to reduce the impact of switching frequency, however, a Lyapunov-based inner loop current controller with an active damping method minimizes the effect of resonance and achieves system stability. The proposed composite controller guarantees the system robustness against grid disturbances and parameter uncertainties. In addition, it eliminates the effect of phase shift and achieves zero steady-state error. The simulation results are presented to demonstrate the performance of the controller.

Keywords: Current control, Double-frequency ripple, DC-link control, Power conversion harmonics, Power quality, non-linear controller, Renewable integration.