Dynamic Available AGC Based Approach for Enhancing Utility Scale Energy Storage Performance

With ever-increasing penetration of non-dispatchable intermittent generation resources in electric grids all over the world, the system operators are facing more challenges to meet the system AGC requirements which aim to maintain the target grid frequency and scheduled tie flows. The utility scale energy storage applications have been often referred to as one of the potential solutions for improving the system frequency response, especially the speed of response. A new concept relating to the use of Dynamic Available AGC (DAA) of the Battery Energy Storage System (BESS) is proposed in this paper and applied in conjunction with the priority and proportional AGC signal distribution strategies. Additionally, this paper proposes an independent AGC control strategy based on Area Control Error (ACE) signal distribution to further enhance the impact of the fast response capability of the BESS. The same is accomplished by means of implementing an independent Proportional Integral (PI) controller without low-order filter typically associated with the ACE signal distribution. The AGC simulation results based on generation trip and normal load variance events, as tested on the El Salvador system model, indicate significant benefits to the system AGC performance when using the concept of the DAA for the BESS and the independent AGC control strategy. The AGC simulation results also indicate that the utilization of 10 MW/3.66 MWh BESS can replace about 36 MW conventional AGC units on the tested system model without compromising on the AGC performance of the system for day-to-day variations experienced in the system load.