A Coordinated Voltage Control Approach for Coordination of OLTC, Voltage Regulator, and DG to Regulate Voltage in a Distribution Feeder

Integration of small-scale electricity generators, known as distributed generation (DG), into the distribution networks has become increasingly popular at the present. This tendency together with the falling price of the synchronous-type generator has potential to give DG a better chance at participating in the voltage regulation process together with other devices already available in the system. The voltage control issue turns out to be a very challenging problem for the distribution engineers since existing control coordination schemes would need to be reconsidered to take into account the DG operation. In this paper, we propose a control coordination technique, which is able to utilize the ability of DG as a voltage regulator and, at the same time, minimize interaction with other active devices, such as an on-load tap changing transformer and a voltage regulator. The technique has been developed based on the concept of control zone, line drop compensation, dead band, as well as the choice of controllers' parameters. Simulations carried out on an Australian system show that the technique is suitable and flexible for any system with multiple regulating devices including DG.

I. Introduction

THE increasing importance of reducing greenhouse gas emissions has been the key drive for a number of Australian government programs that aim to facilitate new generation projects with lower gas emissions than the pool average [1]. These generators are normally intended to operate while electrically connected to the distribution network and utilize renewable energy (hydro, solar, wind, and biomass) or low greenhouse emission fuels (natural gas). They are known as distributed generation (DG) resources. Not only can the connection and operation of DG reduce environmental emissions but it also offers a number of benefits compared with the conventional ones, such as lower capital cost of generation, generation capacity to more closely match the demand, as well as higher potential for enhanced security of supplies and improved power quality [2]. For these reasons, encouragements for installation of the DG units have been growing very fast worldwide in the last decade.