A new approach for load flow analysis of integrated AC–DC power systems using sequential modified Gauss–Seidel methods

SUMMARY The paper describes a new approach for the load flow calculations of integrated AC–DC system. A simple and reliable method for sequential modified Gauss and Gauss–Seidel power flow for AC–DC system is developed. This approach is based on applying nodal injection theory at all buses. The DC system is treated by the current injected to the buses where it is connected and its effect is reflected at internal buses by additional power injection. Iterations between AC and DC power flow algorithms are made to match boundary conditions between the two systems. In this approach, the active and reactive power and the AC voltages at the converter buses are considered as the interface between the AC and DC equations in each iteration step. The combined AC–DC equations are solved separately using sequential modified Gauss and Gauss–Seidel methods. The developed algorithm to solve the AC–DC power flow has been tested on the IEEE 9-bus test system. Copyright © 2011 John Wiley & Sons, Ltd.