Energy Function based Approach for Online Inertia Estimation Utilizing Synchrophasor Measurements

System inertia plays a crucial role in maintaining transient stability in a Power System (PS) network during a disturbance. Increased penetration of Renewable Energy Sources (RESs) into the system, makes the system inertia a variable quantity. Hence, the estimation of the system inertia under such scenarios is becoming more pertinent. In this paper, an energy function based approach is proposed for online inertia estimation using measurements from Phasor Measurement Units (PMUs). The synchronous machine's swing equation is used to emulate the system dynamics. The Potential Energy (PE) at a bus is calculated from the PMU measurement. A novel analogy is established between the inertia constant and the rate of change of PE. Real-Time Digital Simulator (RTDS) is used to illustrate the performance of the proposed approach on the WSCC 9 bus system. The superiority of the proposed approach is investigated by comparing the results with an existing method in the literature.