In this paper, the concept of fractional calculus (FC) is introduced into the sliding mode control (SMC), named fractional order SMC (FOSMC), for the load frequency control (LFC) of an islanded microgrid (MG). The studied MG is constructed from different autonomous generation components such as diesel engines, renewable sources, and storage devices, which are optimally planned to benefit customers. The coefficients embedded in the FOSMC structure play a vital role in the quality of controller commands, so there is a need for a powerful heuristic methodology in the LFC study to adjust the design coefficients in such a way that better transient output may be achieved for resistance to renewable sources fluctuations. Accordingly, the Sine Cosine algorithm (SCA) is effectively combined with the harmony search (HS) for the optimal setting of the controller coefficients. The Lyapunov function based on the FOSMC is formulated to guarantee the stability of the LFC mechanism for the test MG. Finally, the hardware-in-the-loop (HIL) experiments are carried out to ensure that the suggested controller can suppress the frequency fluctuations effectively, and that it provides more robust MG responses in comparison with the prior art techniques.

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Switching sliding mode control (SSMC) can be utilized as a robust control technique, which is appropriate for the control of highly non-linear power systems like chaotic systems. The present study proposes a switching sliding mode control technique for control and chaos suppression of non-autonomous fractional-order (FO) nonlinear power systems with uncertainties and external disturbances. In the first step, a novel fractional switching sliding surface is introduced as well as its stability analysis to the origin is demonstrated. In the second step, based on the fractional version of the Lyapunov stability theory, a robust non-singular control law is designed to ensure the convergence of the system trajectories to the proposed sliding surface. Next, the proposed SSMC approach is utilized for designing a single input switching control technique for the stabilization of a class of 3D FO chaotic power systems. In order to evaluate the effectiveness and robustness of the suggested approach in practice, two examples including control and the stabilization of FO chaotic electric motors are illustrated.

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Introduction: This study was conducted to control hand tremors and decrease adverse effects due to the high field intensity in advanced Parkinson’s disease. We aimed at concurrently controlling two areas of Basal Ganglia (BG) in a closed-loop strategy. Methods: In the present research, two nuclei of BG, namely subthalamic nucleus and globus pallidus internal were simultaneously controlled. Furthermore, to enhance the feasibility of the suggested control strategy, the coefficients of the controller were determined using a hybrid version of the harmony search and cuckoo optimization algorithm. Results: The advantages of the applied method include decreasing hand tremors and applied electric field intensity to the brain; consequently, it leads to reducing adverse effects, such as muscle contraction and speech disorders. Moreover, the purposed controller has achieved superior performance against changing the parameters of the model (robustness analysis) and under noise tests, compared to other conventional controllers, such as Proportional Integrator (PI) and Proportional Derivative (PD). Conclusion: The employed approach provided an effective strategy to reduce hand tremors. It also decreased the delivered high field intensity to the brain; consequently, it reduced adverse effects, such as memory loss and speech disorders. It is important to ascertain the superior performance of the suggested closed-loop control scheme in different conditions and levels of tremor. Such a function was examined in terms of robustness against the variation of parameters and uncertainties. We also obtained time domain outcomes, i.e., compared with the state-of-the-art approaches.