Effects of PEV penetration on voltage unbalance
Balancing loads in low voltage networks is a challenging task due to a continuous fluctuation in the power demand. Voltage unbalance is a condition in which the voltage phasors differ in amplitude and/or do not have its normal 120° phase relationship. This has a potential to introduce technical issues that lead to a costly phenomenon for power distribution system due to the high penetration of Plug-in Electric Vehicles (PEVs). Voltage unbalance study is essential as the propagation of zero sequence component in the distribution system is limited by transformer winding connections and network grounding. Indeed, single phase loads are not affected by unbalance unless the unbalance causes over or under voltages which exceed the acceptable limits. However, the large numbers of PEVs charging from single phase residential feeders of distribution networks may exceed the statutory limits. This chapter presents theoretical discussion with analytical framework for modeling the effects of voltage unbalances due to PEV penetration. A PEV charging profile of a conventional PEV battery has been employed with the daily load demand to synthesize the dynamic effect of PEV penetration. A distribution network topology has been used with unbalanced allocation of single-phase loads and PEVs connected in four-wire, three phase network to investigate the effects of PEV charging on the feeders subject to voltage unbalance. Furthermore, the chapter explores the application of PEV load balancing strategy in the context of smart grid to mitigate the effects of unbalanced allocation of PEVs.