Issues of Capacitive Reactive Power Flow in Electricity Networks

Due to changes in power networks and increased use of power electronics-based devices as consumer loads, utilities are now facing a problem of capacitive (reverse) reactive power flow in electricity networks. In this paper, the field measurement data from Dutch distribution system operator (DSO) and transmission system operator (TSO) is presented which clearly shows the flow of capactive reactive power occurring in electricity networks. Moreover, the historical data illustrates that there is decline of imported reactive power from transmission system to distribution system over the years. Furthermore, in this paper a case study for a modified CIGRE low voltage (LV) distribution network in DIgSILENT PowerFactory is done where first the capactive reactive power situation is simulated using loads with capacitive power factor and then a solution based on smart inverter function is proposed to minimize the capacitive reactive power exchange between LV and medium voltage (MV) network. In this way, by controlling smart inverters available in distribution network we can manage the amount of reactive power flow in the LV network and at the transmission distribution system boundaries.