Operating limits of three-phase multifunctional photovoltaic converters applied for harmonic current compensation

The main objective of a photovoltaic (PV) inverter is to inject the PV power into the ac-grid. Generally, due to variations in solar irradiance, inverters operate bellow their rated current. Therefore, this current margin can be used to ancillary services, such as harmonic current compensation. However, it is necessary to study the photovoltaic inverters voltage and current capability effects during harmonic current injection. In this context, this work presents an algorithm to define the limitations imposed by the dc-link voltage and the inverter current. The algorithm is validated through a simulation and an overview of the simulation characteristics are also presented in this paper. Simulation results show that the algorithm can well estimate the amount of current that can be synthesized by the converter. According to the results, it is demonstrated that the dc-link voltage, the characteristics of the filter and the harmonic order contribute to the amount of harmonic current that can be synthesized by the converter.