Voltage regulation of LV feeders with high penetration of PV distributed generation using electronic tap changing transformers

摘要

As penetration levels of PV Distributed Generation (DG) continue to increase into Low Voltage distribution feeders, electrical utility companies are finding that traditional strategies for managing the voltage profile along these feeders are becoming less effective because of the bidirectional variations in real power flow that are caused by these PV systems. Various strategies have been proposed to resolve this issue, commonly by enhancing the inverter systems of the PV sources to inject reactive power to help flatten the feeder voltage profile. However, such approaches usually require coordinated communication between the PV inverters, and are technically complex to implement. This paper proposes an alternative approach, by incorporating an electronic tap changer into the distribution transformer that supplies the LV feeder so that the LV supply voltage magnitude can step change on a 50Hz cycle by cycle basis. A simple algorithm then varies the transformer tap position as the power flow through the transformer changes, to keep the voltages along the feeder well within regulatory limits irrespective of the magnitude and direction of power flow. The strategy has been confirmed by detailed simulation investigations on feeders with a variety of characteristics, under a wide range of load and PV power injection conditions.