Experimental-Based Evaluation of PV Inverter Harmonic and Interharmonic Distortion Due to Different Operating Conditions

This paper presents the results of comprehensive testing and subsequent detailed analysis of the obtained test results, evaluating harmonic and interharmonic performances of photovoltaic inverters (PVInvs) for a range of different operating conditions. The presented results indicate significant power-dependent changes in harmonic and interharmonic emissions of tested PVInvs for different supply voltage conditions (presence of voltage waveform distortions and various source impedance values). To correctly quantify and describe these changes in PVInv performance, this paper discusses and applies measurement procedures and metrics for evaluating harmonic and interharmonic emission recommended in existing standards, as well as some additional metrics and indicators. For some operating conditions, tested PVInvs significantly increase both harmonic and interharmonic emissions, and this paper also discusses the impact of PVInv control (e.g., maximum power point tracking control) as a possible origin of the interharmonic distortion.