Non-synchronous Inertia Estimation in a Renewable Energy Integrated Power System With Reduced Number of Monitoring Nodes

Accurate estimation of non-synchronous inertia in renewable energy (RE)-integrated power systems is challenging through conventional approaches, as emulated inertia from inverter-based resources (IBRs) is fundamentally different from the inherent inertial response of synchronous generators. In this context, this paper presents a novel realistic approach for estimating the non-synchronous inertial response in a large-scale RE-integrated power system. The method incorporates an optimal number of frequency and voltage monitoring nodes while ensuring an accurate estimation of non-synchronous inertia. In the proposed method, the synchronous inertial response for a frequency disturbance is estimated first using the conventional approach, followed by an estimate of the loads’ inertial contribution. The latter is calculated using center-of-inertia frequency and voltage measurement across the power system with a voltage-controlled zone approach. Finally, the non-synchronous inertial response is estimated by segregating the aggregate inertial response of synchronous generators and the loads from the overall estimated inertia of the system. The proposed approach can help the system operator determine inertial contributions from the loads and IBRs depending on loading conditions and the availability of virtual inertia from RE sources, estimate the minimum required synchronous inertia, and select the appropriate proportional gains and time constants of virtual inertial controllers. The proposed method is validated by implementing it on a modified IEEE 39-bus system and a real-life Gujarat State grid model (in India).