Optimal Coordination of Phase-Shifting Transformers in Curative Congestion Management

Curative congestion management (CCM) and the use of power flow controlling measures such as phase-shifting transformers (PST) increase the complexity of the optimization problem of congestion management. The large scale of today’s transmission grids make linear approximations of the nonlinear power flow equations the state of the art. This paper investigates the impact of linear approximations and potential linearization errors on the (n-l)-security when coordinating PST for CCM. Exemplary results show that remaining congestions occur after curative optimization of PST with a state of the art centralized algorithm that uses linear approximations based on the preventive system state. In an exemplary scenario in the year 2030 the centralized algorithm with a LP core leaves unrelieved congestions of up to 12.9 %. AsLP core leaves unrelieved congestions of up to 2.1 %. Therefore, this paper presents a decomposition approach to solve CCM, which calculates linear approximations in every outage situation.