The study of dependency of power system stability on system inertia constant for various contingencies

Disturbances to an interconnected power system lead to fluctuation of electrical quantities such as voltage, current and frequency. Generally abnormalities lead to fall of system frequency and the initial reaction of the power system to a disturbance is called inertial response of the system which is a function of system inertia constant (H), the higher the system inertia constant the slower the rate of change of frequency (ROCOF) for a system hence the bigger value of this constant refers the higher stability of the system. This paper presents a differential equation for ROCOF, where ROCOF is an inverse function of system inertia constant as well as comparison of system stability for different types of faults inside a system for various inertia constants. Based on the results of the study, it can be concluded easily that the system stability for different contingencies is very much dependent on the overall H constant of the system.