Optimising location of unified power flow controllers using the method of augmented Lagrange multipliers

The unified power flow controller (UPFC) has been proved to be an effective means for regulating voltage profile and power flow in modern power systems. Optimising its location becomes a concern when coming to the practical implementation stage. This paper proposes a mathematical model to work out a pragmatic approach based on the augmented Lagrange multiplier method to determine optimal location for UPFCs to be installed. Investment consideration of UPFCs and real power loss of the network concerned are integrated into the objective functions. The proposed method takes account of steady state security constraints of the power systems represented by models having large scale and nonlinear mathematical properties. Case studies show that the optimally located UPFC can improve the steady state performance and significantly increase the loadability of the system