Cooperation of large-scale wind farm and battery storage in frequency control: An optimal Fuzzy-logic based controller

Grid integration of renewables and battery energy storage systems and its consequent synchronous machines retirement may drive power systems into low-inertia conditions with high risk of frequency instability which is associated with lack of sufficient inertia and primary frequency response previously supplied by synchronous machines. Therefore, there is a need to figure out alternative solutions to compensate the lack of system frequency dynamic supports in future renewable-dominated power systems. In this context, this paper aims to highlight wind farm capabilities, particularly doubly-fed induction generator (DFIG) and permanent magnet synchronous generator (PMSG), in system primary frequency control, similar to conventional synchronous units, while also investigates the synergy between the wind unit cooperation with large-scale battery storages. First, a novel dynamic model is presented which takes into account large-scale wind farms, as well as utility-scale batteries, equipped with frequency-sensitive active power reference scheme so as to control the system frequency violations following contingencies. The proposed frequency control model also includes powerelectronics interface model, its associated control loops, and a novel Fuzzy-logic based controller. The proposed Fuzzy-logic based controller along with a wash-out filter allows combined wind-battery system to estimate the system active power mismatch, emerged from a contingency/trip, to determine the consequent frequency variations, and therefore to deliver fast frequency response in a robust and reliable way to arrest the mentioned frequency distortions. The proposed Fuzzy-based controller is then designed via optimizing its model parameters, including the membership function parameters, thereby improving its efficiency in frequency control provision as well as active power control. The optimization process is performed via a widely used artificial bee colony (ABC) algorithm while a multi-objective function is considered. The proposed frequency control model is then evaluated in the 14-generation low-inertia Australian test system with 30% wind penetration. This work tries to provide a deep insight on how to utilize wind farms for frequency support and how to wind-battery frequency response may positively interact with nearby converter-based resources, i.e., photovoltaic units. The proposed Fuzzy-based coordination approach for large-scale wind-battery units can be a potential solution to deal with frequency stability problems in future power systems with low-inertia conditions including multiple nearby converter-based resources.