Due to the limitation of energy storage output and the problem of overcharging and over-discharging of the state of charge of a single energy storage system during the process of primary frequency modulation
an integrated control strategy based on fuzzy control for hybrid energy storage participation in the primary frequency modulation of the power grid is proposed. Firstly
a hybrid energy storage system is constructed based on the fast-charging and fast-discharging characteristics of supercapacitors and the large-capacity characteristics of batteries
and the sequence of frequency modulation actions is set as supercapacitors before batteries
and batteries before thermal power units. Secondly
a fuzzy controller containing virtual negative inertia control is designed to achieve smooth switching and complementary advantages among different control modes. Meanwhile
adaptive parameters
storage feedback control parameters
and SOC self-recovery output are designed based on the Logistic function to avoid overcharging and over-discharging energy storage. Finally
Matlab/Simulink software is used to build a simulation model
where the proposed integrated control strategy is simulated and analyzed based on the actual power load of the grid. The results show that
compared to the scenario without energy storage
this control strategy reduces the maximum frequency deviation by 61.1% and shortens the time required for the grid frequency deviation to reach a stable value by 82.8%. It effectively enhances the system's frequency regulation capability
improves the output of energy storage
and stabilizes the state of charge of the energy storage equipment.
MARZEBALI M H, MAZIDI M, MOHITI M.An adaptive droop-based control strategy for fuel cell-battery hybrid energy storage system to support primary frequency in Stand-Alone Microgrids[J]. Journal of energy storage, 2020, 27: 101127.
YAN L Q, SHUI T, XUE T L, et al.Comprehensive control strategy considering hybrid energy storage for primary frequency modulation[J]. Energies, 2022, 15(11): 4079.