Calculation of steady-state load flows incorporating system control effects and consumer self-regulation characteristics

Abstract

In standard methods for the calculation of steady-state load flows, based on the swing-bus concept, the effects of automatic generation control, static response of prime movers, consumer self-regulation characteristics and load-shedding action are neglected. Calculations of line flows and bus voltages are unrealistic, particularly in the case of large generation/load disturbances, when both the system frequency and tieline loads deviate from their scheduled values. To overcome this shortcoming, a load-flow model without a swing bus is proposed which takes into account all the relevant actions mentioned above that have been neglected so far. The model is used for load-flow calculations by applying the standard Newton-Raphson iterative procedure for the solution of nonlinear problems, as well as the technique of sparse matrices employed in the solution of a system of linear equations. The method is proved on a sample system of 43 buses and 53 branches of a 220 kV and 400 kV network in the Republic of Serbia. The results obtained from this example justify the use of such a non-standard load-flow model, particularly for security analysis following large generator and tieline outages. © 1981.