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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]

Very high gain and sharp radiation beam of an original antenna array design, made of 16 linear three stacked cylindrical dielectric resonator antennas (three ScCDRA), is proposed in this work for automotive short-range radar (SRR) applications operating at 79 GHz. Firstly, a single antenna which functions around 79 GHz and reaches a gain value up to 11.8 dB is designed with success by piling three cylindrical DRA having permittivity values, respectively, 17.9, 16.9, and 9. However, relatively near peak values, of the main and the side lobs, makes the preliminary design less efficient for vehicle radar applications. To get a radar design with enhance properties, such as lower return loss, higher gain and especially reduced radiation pattern side lobs, we proceeded with an array design of 16 linear antennaelements (1×16). As results, the three ScCDRA array structure provides 21.3 dB as gain peak value, a very narrow angular half power beam width (HPBW) of radiation pattern of 0.7 degree at 79 GHz. Feeding network design and positions of the sixteen linear antenna-elements, within this array, have been extensively investigated to carry out an optimal design still resonating around 79 GHz with a lower S11 parameter value up to -40 dB and hilly directional characteristics of radiation diagram. [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]

Due to the increased penetration of wind energy into the electrical power systems in recent years, the turbine controls are actively occupied in the research. This paper presents a nonlinear backstepping strategy to control the generators and the grid sides of a Wind Farm System (WFS) based Direct Drive Synchronous Generator (DDSG). The control objectives such as Tracking the Maximum Power (TMP) from the WFS, pitch control, regulation of dc-link voltage, and reactive and active power generation at varying wind velocity are included. To validate the proposed control strategy, simulation results for 6-MW-DDSG based Wind Farm System are carried out by MATLAB-Simulink. Performance comparison and evaluation with Vector Oriented Control (VOC) are provided under a wide range of functioning conditions, three-phase voltage dips, and the probable occurrence of uncertainties. The proposed control strategy offers remarkable characteristics such as excellent dynamic and steady state performance under varying wind speed and robustness to parametric variations in the WFS and under severe faults of grid voltage. [ABSTRACT FROM AUTHOR]

As the penetration of the Wind Energy Generation System (WEGS) into the modern power systems is extensively increased, an efficient control strategy of a WEGS plays an essential role in wind power utilization. This study presents Sliding Mode Control (SMC) design for the Variable Speed Wind Farm Systems (VS-WFS) based on Permanent Magnet Synchronous Generator (PMSG) and interconnected to the electric network. The proposed control laws are used to regulate both grid-side and generator converters. The generator side converters are used to track the maximum wind power. The function of the grid side inverter is to transfer the total extracted wind power from DC-link to the electric network and regulate the DC-link voltage. A SMC scheme is developed in the sense of Lyapunov stability theorem for the VS-WFS. Besides, the effectiveness of the proposed SMC scheme is demonstrated by comparison with a traditional Proportional Integral (PI) control strategy for fault conditions as well as for normal working conditions. Simulation results with Matlab/Simulink environment are presented to support the theoretical considerations demonstrating the potential contributions of both control strategies. The proposed SMC scheme can provide excellent control performance than the traditional PI strategy. [ABSTRACT FROM AUTHOR]

• Establish the MPPT with optimal speed ratio combined with hidden layer recurrent neural network (HLRNN) to obtain faster convergence. • Optimize the PI controller gains by using a hidden layer recurrent neural network. • Investigate the active power behavior in the presence of unbalanced grid faults. • Amelioration of the response time of the produced power compared with some other existing neural network schemes. This paper suggests the Hidden Layer Recurrent Neural Network (HLRNN) for controlling a wind power generation system based on a dual-fed induction generator. The generator's stator is connected directly to the electrical grid, while the rotor is linked through bidirectional converters. A PI controller-based Indirect Vector Control (IVC) scheme has been established to pilot the system. The PI regulator allows linear systems to perform well, but when subjected to physical variation conditions, the system's response becomes unstable, making the PI controller insufficient. This paper aims to ensure the PI controller gains self-adaptation regardless of the severity of the circumstances. The effectiveness of the proposed control is demonstrated by taking into account critical conditions such as wind speed changes, generator parameter variations, and asymmetrical faults in the grid. Furthermore, it is confirmed by the enhanced performance and the reduced oscillations during a voltage dip. The simulation results, achieved using MATLAB/Simulink, demonstrate that the response time is reduced to 1.8 (m s), the static error is minimized to 0.16%, and the overshoot is improved to 0.24% when compared to the IVC based on the PI controller and some existing neural network schemes. [ABSTRACT FROM AUTHOR]

The high operating temperature of solid oxide fuel cells, can cause serious damage such as cathode delamination or cracking of the SOFC layers, which cause a decrease in the performance of the latter, a rigorous nondestructive inspection is necessary, in particular that their prices are high. In this paper we have treated thermal control by pulsed infrared thermography of the solid oxide fuel cells electrodes, using 3D finite elements method. The thermal images obtained were processed, and a quantitative analysis was performed to obtain information concerning cracks in electrolyte supported and anode supported planar cells, and cathode delamination in electrolyte supported and cathode supported cells. The results obtained as the temperature distribution in the fuel cells, with and without defects, shows the difference between the flawed and the unflawed cells. The thermal response informs us about the presence of the defects, and in addition it informed us about their depths. • The pulsed infrared thermography technique was applied to the oxide fuel cells damages detection. • The technique is based on an instantaneous pulse light excitation. • The results obtained in term of damages detection show the effectiveness of the technique used. [ABSTRACT FROM AUTHOR]