Saturation Scheme for Single-Phase Photovoltaic Inverters in Multifunctional Operation

Single and three-phase photovoltaic inverters are responsible to extract the photovoltaic array power and inject it into the grid. Due to variations in solar irradiance, inverters have a current margin, which is not explored during the day. Thereby, many works have proposed multifunctional operation. This concept consists in aggregate to the inverter control strategy other functions, such as harmonics and reactive power compensation. However, most important fact and less related in literature is the necessity of techniques to compensate partially reactive power and harmonics of the load, ensuring the inverter work below the rated current. Hence, the present work proposes a current dynamic saturation scheme in order to compensate partially reactive power and harmonics of the load during the multifunctional operation. Simulations show that the dynamic saturation prevents the inverter of inject low-order harmonics while ensuring the operation below the system rated current. By applying the multifunctional operation, the grid current THD is reduced from 104.64% to 1.54% and reactive power is fully compensated, resulting in a considerable grid improvement.