Supercapacitor utilization for power smoothening and stability improvement of a hybrid energy system in a weak grid environment


Abstract: In this paper, a novel control scheme based on the application of a supercapacitor (SC) is proposed for power smoothening and stability improvement of a hybrid energy system (HES) in weak grid conditions. The basic property of fast charging/discharging of the SC is utilized to design the proposed control. In weak grid conditions, the control structure is proposed for power smoothening and DC link voltage regulation with the help of the SC. Moreover, the stability is increased, ripples in voltage are reduced, there is fast dynamic response, and oscillations are damped out under different conditions. In conventional control, voltage controller stability is the main concern under weak grid conditions. On the other hand, the proposed control scheme has independent voltage controller stability in weak grid conditions. Drawbacks of the conventional scheme due to coupling components and large grid impedance in a weak grid are illustrated mathematically. The design and the steady-state stability analysis of the proposed control scheme are explained and compared with the conventional scheme. The HES is modeled and simulated in MATLAB/Simulink to verify the enhanced performance of the proposed scheme. In comparison with the conventional control strategy, the proposed scheme has an improved DC link voltage profile and smoothened power, resulting in the fast dynamic response of the HES connected to the weak grid.

Keywords: Supercapacitor, hybrid energy system, power quality, photovoltaic, weak grid, stability

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