System Identification Based Frequency Nadir Improvement with Synchronous Condenser and BESS in Bulk Transmission Grid

Frequency deviation in a transmission system with a higher frequency nadir is a widespread phenomenon in a power system due to the power and inertia imbalance caused by any disturbances in a power system, which can lead to instability and system blackout. Power imbalance may happen due to changes in load or disturbances (e.g., different types of faults, loss of generations, or loss of lines). The battery energy storage system (BESS), along with a synchronous condenser (SC), in the appropriate position, maybe a promising solution for fast frequency regulation and reducing the nadir. Usually, an SC compensates for inertia deviation while a BESS is linked to the fast frequency response. This paper presents a comprehensive study to show the positioning of a BESS and SC and shows a strategy to reduce the nadir with an inertial frequency response from an SC and a fast frequency response from a BESS. A frequency nadir improvement algorithm, based on the electromechanical mode of the system, is proposed. The analysis is performed on a modified IEEE 9-bus transmission system with real-life parameters for modeling an SC and BESS. The simulation results shows significant improvement in both the frequency nadir (∼sim 75% reduction) and the system stability with the proposed architecture.