On Some Technical Aspects of Transmission and Distribution Networks Interaction

In this paper we analyze some technical aspects of the interaction between transmission and distribution systems that, in our view, could prove very important for power system operation within market environments, particularly for proper determination of the borders between the two subsystems. The interaction is analyzed through three problems: frequency control by controllable loads, voltage optimization and control in transmission system by reactive power compensating devices installed in distribution system, and the need for better reliability analysis for distribution systems. All three problems are supported with simulation results obtained with the help of a synthetic five-bus test system.