A Methodology to Substitute Slack bus under Wide Angle Starting Points using Pseudo Load Flow Formulation

Abstract: Modern power system is very complex and interconnected. The losses that occur in the power system were assigned to slack bus and an equal incremental cost cannot be maintained in Economic Load Dispatch (ELD) problem. In order to overcome this problem, in this paper, a modified power flow analysis by using economic load dispatch is developed. In this method, an additional factor is introduced. Using this, the losses assigned to slack bus are distributed to remaining generator buses so that the equal incremental fuel cost can be maintained in ELD problem. But, there are some cases where the conventional Newton-Raphson (NR) load flow problems failed to converge. In such cases, by using some truncated Taylor series approximations, the pseudo flow equations are developed to obtain the solution. These equations provide a robust starting process for the NR solution of the conventional load flow problem. A methodology to solve more realistic system with wide voltage angles, Pseudo load flow equations is developed. The effectiveness of the developed methodology in obtaining optimal schedules for the generators to solve ELD problem using the conventional NR and developed Pseudo load flow formulations are planned to verify on IEEE-9 bus test system with supporting numerical and as well as graphical results.

Keywords: Economic load dispatch; Pseudo load flow formulation; Removal of slack bus; Load flow approximations.