Effects of Photovoltaic Systems on Power Quality

Renewable Energy Resources (RER) are growing steadily and they are projected to supply all the electricity demand in the future. Currently, wind and solar energy resources have the highest rates of growth, and specifically in the recent years, solar energy has been number one in growth rate among all types of renewable resources. However, dealing with the solar energy's intermittent nature is the main challenge of its utilization. Fluctuations of received solar irradiance can cause significant variations to the output of Photovoltaic (PV) systems. Those output variations can also affect voltage and current at the Point of Common Coupling (PCC) and consequently, power quality of the system. In this work, fluctuations of a PV system due to a cloud shadow are simulated and their effects on Total Harmonic Distortion (THD), and Individual Harmonic Distortion (IHD) during the period in which the cloud shadow passes over the PV system are studied. Simulations results show that decrease in received irradiance caused by the cloud shadow can significantly impact the current THD of the system. Moreover, the effect of the impedance between the utility grid and the PCC on voltage THD is assessed.