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

This paper presents the results of comprehensive testing, and subsequent detailed analysis of obtained test results, evaluating harmonic and interharmonic performance of PV 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 PVInvs’ performance, the 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 emission, and paper also discusses impact of PVInvs’ controls (e.g. maximum power point tracking control) as a possible origin of the interharmonic distortion.