Active power deficit estimation in presence of Renewable Energy Sources

The inertia of the power system is reduced in the presence of Renewable Energy Sources (RESs) due to their low or even no contribution in the inertial response as it is inherently available in the Synchronous Machines (SMs). The total inertia of the grid becomes unknown or at least uncertain following outage of SMs during cascading events. Therefore, the active power deficit following the disturbance/s may not be properly estimated by existing conventional System Frequency Response (SFR) methods in which the total inertia of the power system is required to be known. In this paper, the actual active power deficit is estimated independent of grid inertia, type and number of occurred cascading events after each Load Shedding (LS) stage using shed load amount, pre-shed and post-shed Rate of Change of Frequency (ROCOF). Numerical simulations conducted on IEEE 39 bus standard test system in DigSilent PowerFactory software demonstrates the accuracy of the proposed method.