Active Power Flow Control on Cross-Border Connections

Occurrence of unscheduled electric power flows is one of the most important issues challenging safety of any electric power system. To prevent failures related to the phenomenon, power flows in the system are controlled. This paper contains a review of the causes for which power flow control in a system is necessary, methods used to make flow adjustments, and devices used to control power flows in networks. The practical portion of the presented study includes development of a simulation model for the network with the use of PowerWorld software. Presented are also results of measurements of active power and its losses in the states of equilibrium, increased demand for energy, and with phase shift transformer (PST) and thyristor-controlled series capacitor (TCSC) installed in the system. On the grounds of the obtained measurements it was demonstrated how harmful is the effect of unscheduled active power flows on stability of an electric power system. Moreover, the effect of PST and TCSC on active power flows in the system is discussed including advantages and disadvantages of both device types.