Impact of SOC Estimation on Primary Frequency Regulation for Sustainable Grid Energy Storage System

Abstract

AbstractIn the present scenario, it is very important to concentrate on grid energy storage to maximize renewable energy utilization. Nowadays, commercially feasible projects have been developed to store energy in large level by the development of battery storage technology (BST). In power system, when grid power is lost, battery storage system can deal with the renewable intermittency. Because of intermittent nature, the renewable system provides imbalanced frequency in the grid. So energy storage systems are required to balance the frequency variations by the way of charging and discharging and keep the frequency level at desired limit. Under-frequency events are to be seriously considered and when it happens. State-of-charge estimation is a crucial part in energy management system because SOC estimation involves in modeling and optimizing battery performance in terms of extension of life cycle, cost reduction, and safe operation of batteries for various applications including smart grid application. So estimation of SOC provides a key factor for optimized energy management and control system design. In this paper, equivalent circuit model-based SOC estimation is analyzed based on, mapping of the % of SOC directly with the circuit parameters such as open circuit voltage (OCV) and impedance (Z), and the availability the SOC (tk) is calculated by integrating ampere hour integral method with this one. And also, how the estimation of SOC regulates the grid frequency is also analyzed.KeywordsGrid energy storageBattery storage technology (BST)Imbalanced frequencyGrid frequency regulationSOC estimation