The penetration of photovoltaic (PV) generators into distribution systems is creating new power quality concerns for utility companies in the form of voltage fluctuations resulting from rapid PV output change. This change in PV output is, in turn, caused by transient clouds. Individual clouds can move rapidly across the sky, blocking and unblocking the solar irradiance received by a PV installation. The resulting change in PV generator output can be as high as 80% of its capacity, which can occur within a time-span of just 10 to 30 seconds. When a large portion of the total feeder load/generation profile is comprised of PV generators, the resulting power quality impact can be significant. This report presents research results on the above emerging problem. It includes the characteristics and models of PV output changes caused by transient clouds, a description of the impacts on power quality and utility equipment, methods for analyzing the impacts, and solutions for mitigating the associated power quality issues.
Photovoltaic Systems, Power Quality, Cloud Transients