Operation Limits of Grid-Tied Photovoltaic Inverters with Harmonic Current Compensation Based on Capability Curves

Generally, due to variations in solar irradiance, photovoltaic (PV) inverters operate below their rated current. Therefore, the available current margin can be used to perform ancillary services, such as reactive power control and harmonic current compensation (HC) of nonlinear loads. An important component of the PV system is the passive filter, which attenuates the harmonic generated by inverter switching. The filter may reduce the inverter ability to compensate the harmonic currents. This work presents an investigation of inverter capability to provide HC of nonlinear loads. An algorithm is proposed to determine the capability curves of a multifunctional inverter during harmonic current compensation. The proposed methodology is validated in an experimental setup. The obtained results show that the proposed modeling can estimate with accuracy the minimum required dc-link voltage, when harmonic current compensation is performed by the PV inverter. Also, a sensitivity parameter analysis is carried out. Thus, the main system parameters that affect the inverter capability to provide harmonic current compensation are identified. Furthermore, simulation and experimental results validate the proposed approach.