Current waveform quality from grid‐connected photovoltaic inverters and its dependence on operating conditions

The increasing installation of grid‐connected photovoltaics (PV) in the urban environment will lead to a significant penetration into the low voltage electricity supply network of small power electronic generators. Inevitably some disturbance to the electricity supply quality will result from these embedded generators. It is shown that the inverters used to grid connect PV arrays are susceptible to minor distortion of the network waveform and that this can result in higher levels of current waveform distortion, or harmonic disturbance, being sourced into the supply than would be expected from analyses which assume an ideal voltage waveform. The level of current distortion is shown to be very dependent on the type of inverter control used. Inverter operation is also a function of operating point; clearly a device at part load cannot be expected to deliver the same quality of current waveform as when operating under its rated design conditions. The impedance of the grid connection also has an impact on the inverter's operation. Copyright © 2000 John Wiley & Sons, Ltd.