Fast terminal sliding mode control-based direct power control for single-stage single-phase PV system

Today, grid-connected photovoltaic systems have gained widespread penetration among renewable energy systems. For low power applications, a single-phase inverter with less power converter is a good compromise for high efficiency. The control must make it possible to extract the maximum power from the photovoltaic modules, ensure good dynamic performance for active and reactive power injection, ensure power quality, and reject disturbances and parameter mismatch. Besides, the controllers of the grid and PV sides should be coordinated. In this study, a fast terminal sliding mode control combined with Direct Power Control is proposed. Thanks to the two-cascaded control loops, simulations and experimental results with a 1 kW test bench have proven the proposal's effectiveness in terms of dynamic performances and robustness to irradiance variations. Comparison with deadbeat-Direct Power Control, predictive control, and power hysteresis control shows that our proposal leads to lower Total Harmonic Distortion (3,5%) for the electrical grid's current and lower time response (one-tenth of half the grid cycle).