A Simplified Approach to Steady-State Stability Limits [includes discussion]

A numerical study has been made which shows the effect of shunt loads on the steady-state stability limit of a power system. In particular, the effect of the load characteristic, i.e. constant impedance, or constant current, or constant power, was considered. In general, the study shows shunt loads to have a stabilizing effect on the system except when the load is heavy, nearly constant power in nature, close to a machine which supplies a minor part of the loads requirement, and poorly connected to the rest of the system. On the basis of this study and a-c network analyzer tests, a simplified method for determining the stability limit is developed and presented herein. Equations for the stability limit are also presented.