Utilizing Electric Vehicles to Assist Integration of Large Penetrations of Distributed Photovoltaic Generation Capacity

Abstract

Executive Summary Introduction and Motivation This analysis provides the first insights into the leveraging potential of distributed photovoltaic (PV) technologies on rooftop and electric vehicle (EV) charging. Either of the two technologies by themselves - at some high penetrations – may cause some voltage control challenges or overloading problems, respectively. But when combined, there – at least intuitively – could be synergistic effects, whereby one technology mitigates the negative impacts of the other. High penetration of EV charging may overload existing distribution system components, most prominently the secondary transformer. If PV technology is installed at residential premises or anywhere downstream of the secondary transformer, it will provide another electricity source thus, relieving the loading on the transformers. Another synergetic or mitigating effect could be envisioned when high PV penetration reverts the power flow upward in the distribution system (from the homes upstream into the distribution system). Protection schemes may then no longer work and voltage violation (exceeding the voltage upper limited of the ANSI voltage range) may occur. In this particular situation, EV charging could absorb the electricity from the PV, such that the reversal of power flow can be reduced or alleviated. Given these potential mutual synergistic behaviors of PV and EV technologies, this project attempted to quantify the benefits of combining the two technologies. Furthermore, of interest was how advanced EV control strategies may influence the outcome of the synergy between EV charging and distributed PV installations. Particularly, Californian utility companies with high penetration of the distributed PV technology, who have experienced voltage control problems, are interested how intelligent EV charging could support or affect the voltage control