Investigations Into Conducted Emissions of a 10-kW Photovoltaic Plant

Considering the inverter as the source of electromagnetic emission signals in a photovoltaic (PV) plant, a comprehensive set of measurements of conducted emissions at the input and output of the inverter in a 10-kW PV plant are presented. These are particularly relevant on the backdrop of 1) the ban of products in the EU market due to noncompliance and 2) the increased switching frequency in the inverters
$(\sim 100$
s of kHz) in the near future. Specifically, the common-mode (CM) and differential-mode (DM) currents and voltages are measured, and their frequency-domain behavior is studied. It is suggested that conducted emissions from PV can be classified into three zones: 1) extremely low-frequency (ELF) zone, 2) power frequency zone, and 3) switching frequency zone. Important observations from this exercise are the measurement of harmonic contents of current with total rated current distortion (TRD), imbalance in the output voltage, and low-frequency ripples in the dc voltage. Frequency-domain behavior of the CM quantities is studied which throws light on important points like a relation between input and output CM quantities and a relation between CM voltage and CM current.