Voltage regulation of unbalanced distribution network with distributed generators

Abstract

Distribution networks are not perfectly balanced all time due to the nature of dynamic loads in the system. Photovoltaic (PV) systems started to be integrated into these distribution networks as distributed generators (DG) through inverters. In addition, wind turbines also started to be integrated but not as distributed as PVs. Both DGs have a fluctuating power outputs due to the intermittent resources that can affect the voltage profile of the system and can also increase the OLTC operation which has limitation on precise voltage regulations as well as on response time to the voltage changes. Inverters can reduce these effects and regulate the voltage by injecting reactive power. This paper presents a study on the distributed PV voltage control of an unbalanced distribution network that includes OLTC and wind turbine generation at the substation. Single phase PV and OLTC voltage control is proposed. In addition, the wind turbine impact on distribution network is investigated. IEEE 13 bus distribution network is simulated in Matlab Simulink and feeder bus voltages are monitored when OLTC, PV, and wind turbine provide voltage regulation. Results show that voltage profile of point of common coupling stays within the limits with the help of PV single phase voltage regulation. The OLTC operation depends on the PV voltage control and injected power amount. Results also show that the OLTC operation is reduced with the PV voltage control and wind turbine has impact on the voltage profile.