Achieving AC Power Flow Convergence Through Generator Active Power Re-Dispatch

The importance of a converged AC power flow (ACPF) case cannot be overstated, as it forms the foundation of other power systems studies. However, achieving a converged power flow model can be particularly difficult due to the non linear nature of the power flow equations. Convergence is further affected when excessive power flows through certain transmission lines causing significant overloads. This paper addresses this challenge by developing an algorithm that achieves ACPF convergence by re-dispatching the active power of selected generators to alleviate congestion on critical transmission lines, thus restoring the ACPF case to a solvable operating point. The algorithm performs the re-dispatch using the bus mismatch data from the initial diverged ACPF case and DC power flow based linear distribution factors. This method was implemented on the 6102-bus Electric Reliability Council of Texas (ERCOT) grid under multiple operating conditions and successfully facilitated the convergence of 64 cases out of 74 non-converging ACPF cases. Additionally, the voltage quality of the newly converged cases are analyzed. Key words. AC Power Flow Convergence, Generator Redispatch, Distribution Factors, DC Power Flow, Transmission Line Congestion