Investigation of the interaction between step voltage regulators and large-scale photovoltaic systems regarding voltage regulation and unbalance

The number of installed photovoltaic (PV) systems has been increasing in an unprecedented rate every year throughout the world. In some situations, the PV systems can provide more power than the demand in certain parts of a network and cause reverse power flow, which the traditional distribution networks are not designed for. Consequently, these instances may result in adverse interactions between PV systems and voltage regulation devices such as step voltage regulators (SVRs). This can potentially drive voltage magnitudes beyond acceptable limits and possibly damage consumers’ appliances. In the literature, such interaction cases with consideration of realistic three-phase four-wire unbalanced networks have not yet been reported. Therefore, this study analyses the interaction between SVR and PV systems in a real-world network by utilising the quasi-static time-series technique for a long-term statistical assessment. This evaluation focuses on examining voltage regulation issues in an unbalanced three-phase four-wire network along with an open-delta SVR configuration, and the corresponding solution is proposed to resolve the concerning issues. The results of this study will provide valuable information on interaction characteristics to academia and utilities for assessing large-scale PV system integration.