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The article suggests employing second-order sliding mode control (SOSMC) to manage photovoltaic systems (PVS) connected to the electrical grid. These systems face complexities due to non-linearities, variability, uncertainties, disturbances, and climate changes. The proposed control strategy utilizes two converters: one at the photovoltaic generator (PVG) side for maximum power point tracking (MPPT) to optimize energy generation and another at the grid connection point to regulate power injection into the grid and maintain the DC bus voltage (Vdc) while achieving unit power factor (UPF). Both converters are equipped with SOSMC controllers, enabling independent adjustment of active (P) and reactive (Q) power. This approach aims to enhance the energy efficiency and robustness of PVS under varying climatic conditions. The performance of the system is evaluated under standard and variable irradiation conditions using the MATLAB/Simulink environment. Simulation results indicate that SOSMC significantly improves system performance and efficiency compared to conventional vector control (CVC). Notably, it reduces active power overshoot by 100%, decreases Vdc response time, and lowers total harmonic distortion (THD) of the current to 1.19%, demonstrating its effectiveness across different irradiation levels. [ABSTRACT FROM AUTHOR]

This paper proposes a Nonlinear Backstepping Approach (NBA) to improve the control performance of a Permanent Magnet Synchronous Generator (PMSG)-based Wind Energy Generation System (WEGS) under parameter uncertainties and short circuits with fluctuations in the grid voltage. Both the rectifier and the three-phase inverter are controlled using the NBA scheme; this method ensures Maximum Power Point Tracking (MPPT), which is a very appealing control objective with unpredictable scenarios of wind speed, and regulates the active and reactive power flows to the electrical network under varying wind speeds. Also, an inverter was employed to control voltage of the DC bus and the powers. The regulator's stability is achieving using the Lyapunov approach. Simulation results with Matlab/Simulink confirm the efficiency of the presented scheme. The comparative analysis of the NBA with conventional Vector Controllers (VCs), under parameter deviations and for low voltage drop conditions, demonstrates the efficiency of the studied method. [ABSTRACT FROM AUTHOR]

Thermoelectric devices are one of the technologies used either to generate electricity by applying a temperature difference using thermal energy or as a heating/cooling system by applying an electrical voltage. The number of materials required to produce a product is an important factor in determining its price. Production costs associated with these materials, as well as their availability and quality, play a crucial role in price determination by manufacturers. In this context, a method that employs a uniform volume distribution was implemented. This approach enabled the analysis to focus on other variables, thereby promoting a more precise and relevant evaluation of overall performance. Based on the finite element method, this study investigated the influence of geometric shape, including Rect-leg, Y-leg, Pin-leg and X-leg designs, on the performance of solar thermoelectric generators and thermoelectric coolers. The study was conducted considering the same hot alumina junction surface that receives solar radiation; however, the effective surface, which corresponded to the heat flow area and had a similar area near the exposed surface, varied depending on the chosen leg geometry, thus impacting the heat flux due to the variation in thermal resistance. In the case of a solar thermoelectric generator, the Rect-leg model, having the same effective surface area, presented the lowest heat loss value resulting from convection and radiation in the heat spreader and the hot alumina plate. Under the same conditions, the Y-leg showed the highest value. The Rect-leg design generated, by using thermal and optical concentration, the highest output power of 0.028 and 0.054 W, and efficiency of 3.47% and 4.7%, respectively, whereas the Y-leg generated lower values of 0.006523 and 0.018744 W for power, and 2.83% and 2.71% for efficiency, respectively. In the case of the thermoelectric coolers, the Y-leg generated the highest temperature difference between the hot and cold sides of 67.28 K at an electric current value of 1.8 A, whereas the Rect-leg, Pin-leg and X-leg generated ~66.25, ~67.02 and ~67.19 K at 6.1, 2.7 and 2.6 A. [ABSTRACT FROM AUTHOR]

This paper proposes a nonlinear optimal Backstepping method for controlling the doubly-fed induction generator used in wind energy conversion and obtainingmaximum power. The grid is connected directly to the stator. The rotor, on the other hand, is connected to the grid via two bidirectional converters. This work aims to regulate active and reactive power while maintaining a unit power factor using the proposed controller. The Lyapunov function guarantees the stability of the system. The most challenging aspect of Backstepping is determining the best positive constants, which are critical to the system performance. This process becomes more complex, especially when the generator parameters are uncertain or when the wind profile varies. As a result, optimizing the gains is an essential aspect of the controller design. The particle swarm optimization method is suggested for determining the optimum Backstepping constants. The performance and robustness of the proposed method are investigated and compared to the Conventional Backstepping and the Proportional-Integral Control strategies of a 5 MW wind power plant system under parameter variations and quickly changing wind speed profiles. Matlab/Simulink makes it possible to get results. The advised methodology ensures the tracking system's robust stability and reduces the response time to 1.8 (m s). Furthermore, it guarantees a negligible static error. [ABSTRACT FROM AUTHOR]