Coordinated voltage and reactive power control scheme for smart grids with distributed generation

The presence of distributed generation (DG) in electrical grids increases the complexity of the regulation process because the injection of power from these sources, which is intrinsically random for generators based on renewable sources, can alter the voltage profiles on the network buses. This requires the design of a suitable methodology aimed at assuring effective grid operation by the optimal coordination of DGs operations with traditional voltage regulating devices. In this paper, a coordinated voltage-control (CVC) scheme for smart grids with distributed generation depending on system conditions is introduced. Based on voltage and reactive power constraints three states are defined in which roles (Master/Slave)of the devices (DGs, OLTCs) are interchanged to allow maximum reactive power reserve for DGs. A mathematical formulation of optimal VAR control problem is performed for all the states in order to minimize the system real power loss. The 12-Bus test system is modified with DGs connected. Application of algorithm to the test system results in reduced system losses and improved voltage profile.