Voltage control in radial systems with dispersed generation

After the introduction of the competitive electricity market in many countries, the number of small-size generators connected to the distribution systems is rapidly increasing. This paper analyses the interactions among the voltage control operated in the HV/MV substation and the possible voltage control operated by the dispersed generators connected to the MV nodes of the distribution system. A novel controller of voltage and reactive power of the dispersed generator is proposed. With this controller, when the voltage at the network side remains in an acceptable range, the reactive power generation of the dispersed generator is null with minimum losses for the generator and its transformer; otherwise, the dispersed generator gives an additional contribution to control the voltage of the system. Results showing the effectiveness of the proposed controller are presented for an actual distribution system.