ULTC Control based on Remote Voltage Monitoring in Distribution System with Distributed Generations

M. Kim, R. Hara, and H. Kita (Japan)


Distributed generation, voltage regulation, under load tap changer (ULTC)


Distributed generation (DG) has become an essential and indispensable element from environmental and energy security perspectives. However, because the unpredictable and unstable output from DG may give some effects on the voltage profile on distribution feeders, the regulation of sending voltage that satisfies the receiving voltages even when DGs were interconnected is very difficult. Generally, sending voltage at substation in distribution systems is regulated by an under load tap changer (ULTC) so that customer’s receiving voltages can be maintained within a predetermined range. Since the conventional control schemes such as program and LDC (Line Drop Compensation) does not consider the presence of DGs, more sophisticated and flexible voltage regulation methods should be developed to enhance the system’s acceptability for DG interconnection. This paper proposes a new control method for ULTC which can improve the control performance and enhance the maximum installable DG capacity. The availability of the proposed method for multiple feeders is studied through numerical simulations of Korean 22.9[KV] model system.

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