HESS Sizing Methodology for an Existing Thermal Generator for the Promotion of AGC Response Ability

Due to the increasing penetration of renewables, power systems with lower inertia may result in larger frequency excursion. The emergency of new inertia and fast-frequency response characteristics made energy storage systems (ESSs) much more attractive in recent years. ESS can largely improve the frequency regulation capability of a traditional thermal generating unit with relatively slow ramp rate. In this paper, a novel method for sizing a hybrid energy storage system (HESS) to improve automatic generation control (AGC) response of an existing thermal generator is presented, which strikes a right balance between the extra benefit from faster AGC response and the increased HESS cost. First, a novel control scheme for HESS is proposed to improve both the AGC response speed and the precision of a HESS-generator system. And then, based on the benefit analysis of AGC response, a novel cost-benefit-based optimization model is presented for HESS configuration with the aim of maximizing the AGC response benefit of HESS-generator system. Finally, using actual historical data, the simulation is conducted to demonstrate the effectiveness of the presented sizing methodology.