Load frequency fractional‐order controller design for shipboard microgrids using direct search alghorithm. Issue 4 (26th November 2022)

• Record Type: Journal Article
• Authors: Bahrampour, Elham; Dehghani, Maryam; Asemani, Mohammad Hassan; Abolpour, Roozbeh
• Is Part Of: IET renewable power generation. Volume 17:Issue 4(2023)
• Page Start: 894
• Page End: 906
• Publication Date: 2022-11-26
• Subjects: Renewable energy sources -- Periodicals; 333.79405
• DOI: 10.1049/rpg2.12643
• Languages: English
• ISSNs: 1752-1416

Abstract

Abstract: Load frequency control (LFC) is one of the controversial topics in power systems, especially in shipboard microgrids (SMG). In such applications, renewable energies such as wind, solar, or wave energies provide the power supply. However, changes in the weather conditions or loads can disrupt the frequency. To have a constant frequency in the presence of such turbulence in SMG, a fractional‐order dynamic output feedback controller (FDOFC) is proposed. As a result, the closed‐loop system is extended to a non‐identical fractional‐order system in the state space model. First, the non‐identical fractional‐order system is transformed into an identical one using the least common multiple techniques to determine control parameters. Subsequently, using a direct search algorithm, a considered initial design space is divided into smaller totally stable (TS) sub‐spaces. Then, among all TS controller parameters, the H ∞ $H_{\infty }$ controller is designed to reduce the effects of disturbances. The study is carried out on a practical SMG system to show the practicality of the proposed FDOFC. Finally, to evaluate the proposed method's efficiency, the SMG results are compared with the results obtained with μ synthesis, H ∞ $H_{\infty }$, Bilinear Matrix Inequality (BMI)‐based, and fuzzy fractional optimization methods. Compared to the state‐of‐the‐art approaches, more promising results are obtained for H ∞ $H_{\infty }$ ‐norm of the closed‐loop system about ten times smaller, that is, | | Δ f | | ∞ = 0.00026 $||\Delta f||_\infty = 0.00026$ which is such a negligible norm that concludes perfect disturbance rejection. Moreover, in more scenarios, the robustness of the designed framework is evaluated under parameter variations and time delays in communication. The results show that the maximum frequency deviation is 2.5 × 10 − 3 $2.5 \times 10^{-3}$, which is very small. Therefore, the controller also works impressively under deviations of SMG system parameters, and communication time delays. Abstract : We propose a fractional‐order dynamic output feedback controller (FDOFC) to have a constant frequency in the presence of turbulence in SMG. Using a direct search algorithm, a considered initial design space is divided into smaller totally stable (TS) sub‐spaces; and among all TS controller parameters, the H? controller is designed in order to reduce the effects of disturbances. To evaluate the efficiency of the proposed method, the obtained SMG results are compared with the results obtained with ? synthesis, H?, Bilinear Matrix Inequality (BMI)‐based, and fuzzy fractional optimization methods.