Optimal daily coordination of volt/VAr control devices in distribution systems with distributed generators

As the impacts of distributed generators (DGs) on distribution systems are significant, this paper proposes a particle swarm-based optimization technique to define an optimal coordination of DGs, an under load tap changer (ULTC) including substation and feeder capacitors for volt/VAr control. The objective for the coordination is considered in the view point of the distribution system operators as to minimize the summation of daily energy payment for DGs´ owner and energy loss cost. Case study is conducted with a modified 29-bus distribution system of Provincial Electricity Authority (PEA), Thailand. It is found that the obtained optimal coordination strategies meet the requirement of the objective function and can help improve the system performance while satisfying all the technical and functional constraints.