Equivalent system frequency response model with energy storage

Providing Frequency Response (FR) using energy storage system (ESS) has been adopted in power systems worldwide to reduce the maximum frequency deviation. This paper presents a new equivalent system frequency response model with ESS. The model can be conveniently used to assess the system frequency nadir and calculate the capacity and equivalent droop of storage considering the maximum frequency deviation in a synchronous generator (SG) dominated system. Unlike existing calculation methods based on control strategies such as fuzzylogic, robust control, data-driving control and predictive algorithm, the proposed method (i) uses the equivalent capacity and equivalent droop to describe the FR of SG and ESS, thereby avoids the difficulty in solving highorder FR model and (ii) does not need the control strategy of SGs in the network. Therefore, the proposed method provides a simple yet systematic method in calculating the capacity and equivalent droop of ESS. The effectiveness of the proposed method is demonstrated using the four-generator two-area (4G2A) system with 0 %, 25 % and 50 % penetration of renewable resources and different types of SGs (hydraulic and steam SG) based on the given maximum frequency deviation..