Dynamical model of unified power flow controllers in load-flow analysis

Based on the novel concept of interpreting the updated voltage solutions at each iteration in the Newton-Raphson (NR) load-flow analysis as dynamic variables, the paper develops a procedure for representing the unified power flow controllers (UPFCs) in the steady-state evaluation. Both the shunt converter and series converter control systems of a UPFC are modeled in their dynamical form with NR iterative step as the discrete independent variable in the load-flow analysis. The key advantage of the method developed is that of facilitating the process of constraint resolution during the NR solution sequence. Any priority in control functions pre-set in the UPFC controllers is automatically represented in the load-flow formulation. The method developed together with its software implementation is tested using a representative power network with UPFC