This paper proposes a novel controller for the secondary load frequency control of a shipboard microgrid. The suggested controller is based on the linear matrix inequality technique and the Lyapunov stability theory. In the controller design procedure, the effects of the sensor-to-controller and controller-to-actuator delay communication links are considered, and a robust controller against the delay is proposed by utilizing a Lyapunov–Krasovskii functional. In addition, due to the practical space limitation of a ship, low-space, high-efficient renewable energy sources (RESs), and energy storage systems are considered. Furthermore, a diesel generator and a proton exchange membrane fuel cell are employed to effectively mitigate the frequency oscillations arise by the loads and RES power variations. Finally, to show the merits of the proposed method, several hardware-in-the-loop real-time simulations are performed. Comparison results illustrate the effectiveness of the proposed approach to the state-of-the-art methods.

This paper investigates the injecting power stabilization of nonlinear dc microgrids (MGs) with constant power loads (CPLs). By considering a centralized controller scheme, the limitations of the communication utilities are considered. Therefore, limited information is transferred through the nonideal noisy communication network. Consequently, a cubature Kalman filter (CKF) with a third degree is proposed to mitigate the effect of the noisy measurement and the noisy network on the system's information. Moreover, an estimation-based robust feedback controller is developed to design an optimal value for the injecting power. The considered CKF algorithm is robust against the system uncertainty and noisy environments and has a low computational time for high-order dc MGs with a high number of sources and CPLs. In addition, a systematic procedure to compute the feedback gain of the controller is presented, which can be numerically solved by linear matrix inequality techniques. Hardware-in-the-loop real-time simulation results verify the simplicity of the controller implementation, enhanced performance for the case of limited information, and better robustness against the noisy measurements compared to the state-of-the-art methods.

This article develops a novel decentralized controller for multi-area secondary load frequency control (LFC) of power systems. The proposed robust-adaptive approach estimates the external disturbance input and uncertainties, which are assumed to be matched with the control input. In this regard, a disturbance-observer state-feedback controller is designed. To offer a systematic approach, controller design conditions are derived in terms of linear matrix inequality constraints. Thereby, for any given representation of the LFC area, the controller gains can be straightforwardly obtained by using numerical solvers. Moreover, in order to enhance the steady-state performance, the controller is modified through the heuristic genetic algorithm. The controller design procedure is wholly offline and can be simply implemented. The developed decentralized approach does not need the information of the other areas, which reduces the cost and the number of measuring units. It is also robust against the power fluctuations of the load and renewable energy sources. To show the superiorities of the developed controller, four scenarios are considered. These scenarios comprise the aggregation of the photovoltaic, wind turbines, and electric vehicle to the power system. OPAL-RT experiments are given to verify the transient and steady-state performance and robustness of the proposed controller.

This paper proposes a novel controller for the secondary load frequency control (LFC) of an alternating current shipboard microgrid (MG). The suggested controller is based on the robust μ-and mixed μ-synthesis in which the structured system uncertainties and external disturbance inputs are considered in the design procedure of the controller. The offline designed controller is resilient against the power fluctuations of the load and renewable energy sources (RESs), such as solar and wave energies. The output of the controller manipulates a diesel generator, as well as energy storage systems (ESSs) to effectively regulate the frequency of the AC MG to the desired value and reduce the frequency oscillations originated by the loads and RES power changes. Several hardware-in-the-loop (HiL) real-time dSPACE emulator-based simulations have been performed to show the effectiveness of the suggested robust control scheme. Additionally, comparison results are provided to better highlight the advantages of the proposed μ-synthesis-based approach over the state-of-the-art techniques.

This paper presents fault tolerant controllers for a class of one‐sided Lipschitz nonlinear systems with external disturbances. A sliding mode observer (SMO) is integrated with the H_∞ filtering approach as the fault detection and isolation module. The problem is investigated in the presence of faults and disturbances simultaneously. The H_∞‐SMO is capable of approximating faults accurately, while reducing the effect of disturbances in the estimation of the state vector and occurred faults. Accordingly, using only a single SMO, the estimation error of the state vector and faults can be made simultaneously arbitrarily small. In addition, to deal with the weighted bilinear form appearing in the one‐sided Lipschitz condition, the quadratically inner bounded condition presented in the literature is employed in this paper as a useful solution. The proposed method guarantees the stability of the overall closed‐loop system, and after a short transient time, the estimation errors for state vector and fault signal converge to a small neighborhood of the origin. The effectiveness of the presented algorithm is confirmed in two examples including a single arm robot with a flexible joint and a numerical simulation.