Impact of smart inverter control with PV systems on voltage regulators in active distribution networks

Multiple voltage regulating devices, such as on-load tap changer (OLTC), step voltage regulators (SVRs), switched capacitors banks work in tandem with each other to regulate voltage in the distribution network. These conventional devices can be controlled in various ways based on either centralized or decentralized management system. When photovoltaic (PV) systems are operated with smart inverters, SVRs need to coordinate with them in order to regulate the critical bus. Depending on the high ramp up or ramp down condition in the morning and late afternoon respectively, SVR operations may not be able to keep voltages within the acceptable band. This paper presents the relationship of PV active and reactive power with SVR step changes, and proposes an algorithm to coordinate the SVRs with the PV inverters capability to curtail active power and absorb reactive power as needed to improve the power quality. The algorithm is tested on the modified IEEE-13 bus test feeder.