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The challenges of modern power systems with a high level of renewable generation penetration will impose increased ancillary service on Photovoltaic (PV) systems, including frequency regulation. In this paper, a frequency regulation strategy for PV systems without energy storage is proposed. The proposed strategy is divided into two layers: the frequency regulation layer and the power reserve control layer. In the power reserve control layer, a novel power reserve control is proposed as the core element and novel feature. The existing power reserve control for PV systems must estimate the maximum available power, which is difficult because of the variation in environmental conditions and complex modeling of PV systems. Instead, a power tracking control method based on a curtailment power-current curve is proposed. It can automatically track a given reserve ratio under any environmental condition without an irradiance sensor. In the frequency regulation layer, the combination of droop control and virtual inertia control is used to adjust the given power reserve ratio. Simulation results show that the proposed strategy offers good accuracy and tracking speed and can significantly improve the frequency response of the power system.

Accurate estimation of lithium battery state of charge is very important for ensuring the operation of battery management system, realizing the energy management strategy of electric vehicles, reducing mileage anxiety and promoting the sustainable development of electric vehicles. In this paper, several studies are carried out for state of charge estimation of lithium-ion battery: (1) Aiming at the problem of parameter identification of battery model, an optimal identification method of model parameters based on ant lion optimization algorithm is proposed. (2) An adaptive weighting Cubature particle filter (AWCPF) method is proposed for SOC estimation. The proposed AWCPF method is based on particle filter (PF) algorithm, while the Cubature Kalman filter (CKF) algorithm is utilized to generate the proposal distribution for PF algorithm, which can retrain the particles degradation problem in PF algorithm. To solve the problem that the CKF algorithm is sensitive to noise, comparing with fixed sigma point weights of the conventional CKF, the weights of sigma points are adaptively adjusted based on state and measurement residual vectors. Furthermore, the process noise and measurement noise are estimated iterative. In this paper, experimental verification of different initial values of SOC under various working conditions is carried out. The results show that the proposed AWCPF algorithm based SOC estimation method has high estimation accuracy, strong robustness, fast convergence speed, with the maximum SOC estimation error is less than 1%.

This paper considers the off-line roadside unit (RSU) ON/OFF scheduling problem in a sparse vehicular ad hoc network (VANET). We formulate the problem as a mixed integer non-linear programming problem and propose a heuristic scheduling algorithm called Multi-Level Greedy (MLG) algorithm to find a suboptimal approximation. In the proposed MLG algorithm, we introduce the concepts of optimal service location and suboptimal service location. Then, we obtain the ON-OFF state matrix of RSUs. Simulation results show that the MLG algorithm can significantly reduce the energy consumption of RSUs deployed and can provide a reference basis for energy efficient scheduling in VANETs.

Transverse flux permanent magnet (TFPM) machines are a potential candidate for direct-drive wind power application due to high torque and power densities. The operating principle of TFPM machines is firstly described with various topologies available in literature, with the placement of magnets as a criterion for the classification of TFPM machine topologies. This review includes characteristics, power factor improvement, cogging torque minimization, material consideration, modelling techniques, and scalability. Different wind turbine concepts with direct-drive machines, control techniques and power converter topologies are also considered in this paper.

Increasing the use of electric vehicles (EVs) is regarded as a step in the right direction to reduce air pollution and carbon emissions. However, a dramatic increase of EV and charging stations has raised voltage quality and harmonic distortion issues that affect the performance of integrated renewable power sources (wind and solar) and smart-grid electrical transmission networks. This paper models an integrated electric vehicle charging and battery storage system operating in the presence of unpredictable wind and solar power sources. The aim is to enable the design of an electrical control system that develops the correct duty cycle to stabilize and regulate the voltage at the dc/dc power conversion station. Simulations are performed to evaluate energy management by the proposed control system. The proposed system effectively manages the electric power on the grid by drawing power from the batteries at peak times and then charging them in off-peak times, reducing the load on the converter and enabling the reduction of charging time for electric vehicles. A constant voltage is achieved on the grid irrespective of fluctuations in renewable energy generation and in the load.

This paper investigates a linear generator (LIG) for application in high speed maglev train. Its configuration and working principle are introduced in detail. The mathematic models of magnetic field and induced voltage are established by the equivalent magnetic circuit method and the law of electromagnetic induction respectively, through which the characteristics of LIG and impact factors are analyzed preliminarily. An analytical and numerical method is proposed to analyze the characteristics of LIG further, in which the finite element model is applied to calculate the magnetic field accurately and the analytical model is used for the induced voltage calculation in a discrete way. The relationships of induced voltage amplitude and speed, induced voltage frequency and speed are clarified, providing the basis for the design of power supply system on vehicle. Finally, the experiments for the magnetic field and induced voltage are carried out on the performance test bench of magnet and real vehicle respectively to validate the analysis results.

Hydraulic transformer is a significant component to develop the future energy saving hydraulic systems; however, the speed stability is one of the problems in such a machine because the rotor is unconstrained and the rotary inertia of the rotor is small. In this paper, aiming at the rotating speed of hydraulic transformer, a hydro-dynamic model of is proposed considering the nonlinear friction, oil compressibility and leakage. Both simulation and experiment are carried out to validate the hydro-dynamic model. Moreover, this paper theoretically analyzes the low-speed stability of hydraulic transformer based on the hydro-dynamic model for the first time. The mechanism of creep is discussed and the creep judgment method is presented. The influence of each parameter on creep is investigated, and the possible ways to avoid creep are explored. The calculations of the lowest stable rotating speed and the lowest stable flow rate without creep are given. This study is significant for the design and practical application of hydraulic transformer in the future.

Las plantas solares fotovoltaicas (PV) a gran escala desempeñan un papel esencial para satisfacer la creciente demanda de energía en los últimos tiempos. Por lo tanto, con el propósito de lograr la mayor potencia cosechada en las condiciones de sombreado parcial, así como de proteger la matriz fotovoltaica de la calamidad del punto caliente, la estrategia de reconfiguración fotovoltaica se establece como un procedimiento eficiente. Esto se realiza mediante la redistribución de los módulos fotovoltaicos de acuerdo con sus niveles de sombreado. Motivados por esto, los autores de este artículo han introducido un nuevo algoritmo basado en la población que se conoce como algoritmo de depredadores marinos (MPA) para reestructurar dinámicamente la matriz fotovoltaica. Además, se introduce una función objetivo novedosa para mejorar el rendimiento del algoritmo en lugar de utilizar la función objetivo ponderada regular en la literatura. La efectividad de los algoritmos propuestos basados en la función objetivo novedosa se evalúa utilizando varias métricas como el factor de relleno, las pérdidas por desajuste, el porcentaje de pérdida de potencia y el porcentaje de mejora de potencia. Además, los resultados obtenidos se comparan con una conexión regular de enlace cruzado total (TCT), optimización de forrajeo de mantarrayas (MRFO), optimizador de halcón de Harris (HHO) y técnicas de reconfiguración basadas en optimizador de enjambre de partículas (PSO). Además, para demostrar la idoneidad de los métodos propuestos, se consideran y evalúan matrices fotovoltaicas a gran escala de $ 16\ times16 $ y $ 25\ times25 $. Los resultados revelan que el MPA mejoró la potencia de la matriz fotovoltaica en un porcentaje del 28,6 %, 2,7 % y 5,7 % en los casos de matrices fotovoltaicas de $ 9\ times9 $, $ 16\ times16 $ y $ 25\ times25 $, respectivamente. Las comparaciones exhaustivas respaldan que el MPA muestra una dispersión de sombra exitosa; por lo tanto, el número de picos múltiples en las características fotovoltaicas se ha reducido, y se han cosechado altos valores de potencia con el menor tiempo medio de ejecución en comparación con PSO, HHO y MRFO. Además, se ha realizado la prueba de rango con signo de Wilcoxon para confirmar la fiabilidad y aplicabilidad del enfoque propuesto también para las matrices fotovoltaicas a gran escala. Les centrales solaires photovoltaïques (PV) à grande échelle jouent un rôle essentiel pour répondre à la demande croissante d'énergie ces derniers temps. Par conséquent, dans le but d'atteindre la puissance récoltée la plus élevée dans les conditions d'ombrage partiel ainsi que de protéger le réseau photovoltaïque contre la calamité du point chaud, la stratégie de reconfiguration du PV est établie comme une procédure efficace. Ceci est effectué par redistribution des modules PV en fonction de leurs niveaux d'ombrage. Motivés par cela, les auteurs de cet article ont introduit un nouvel algorithme basé sur la population qui est connu sous le nom d'algorithme des prédateurs marins (MPA) pour restructurer dynamiquement le réseau PV. De plus, une nouvelle fonction objective est introduite pour améliorer les performances de l'algorithme plutôt que d'utiliser la fonction objective pondérée régulière dans la littérature. L'efficacité des algorithmes proposés basés sur la nouvelle fonction objective est évaluée à l'aide de plusieurs paramètres tels que le facteur de remplissage, les pertes de désadaptation, le pourcentage de perte de puissance et le pourcentage d'amélioration de puissance. En outre, les résultats obtenus sont comparés à une connexion totale croisée (TCT) régulière, à une optimisation de recherche de nourriture par raie manta (MRFO), à un optimiseur harris hawk (HHO) et à des techniques de reconfiguration basées sur un optimiseur d'essaim de particules (PSO). De plus, pour démontrer la pertinence des méthodes proposées, des réseaux photovoltaïques à grande échelle de $ 16\ times16 $ et $ 25\times25 $ sont considérés et évalués. Les résultats révèlent que le MPA a augmenté la puissance du réseau photovoltaïque de 28,6 %, 2,7 % et 5,7 % dans les cas des réseaux photovoltaïques $ 9\ times9 $ , $ 16\ times16 $ et $ 25\ times25 $ , respectivement. Les comparaisons complètes confirment que la MPA montre une dispersion d'ombre réussie ; par conséquent, le nombre de pics multiples dans les caractéristiques PV a diminué, et des valeurs élevées de puissance ont été récoltées avec le temps d'exécution moyen le plus faible par rapport à PSO, HHO et MRFO. De plus, le test de Wilcoxon a été réalisé pour confirmer la fiabilité et l'applicabilité de l'approche proposée pour les réseaux photovoltaïques à grande échelle. Large-scale solar photovoltaic (PV) plants play an essential role in providing the increasing demand for energy in recent time. Therefore, in the purpose of achieving the highest harvested power under the partial shading conditions as well as protecting the PV array from the hot-spot calamity, the PV reconfiguration strategy is established as an efficient procedure. This is performed by redistribution of PV modules according to their levels of shading. Motivated by this, the authors in this article have introduced a novel population-based algorithm that is known as marine predators algorithm (MPA) to restructure the PV array dynamically. Moreover, a novel objective function is introduced to enhance the algorithm performance rather than utilizing the regular weighted objective function in the literature. The effectiveness of the proposed algorithms based on the novel objective function is evaluated using several metrics such as fill factor, mismatch losses, percentage of power loss, and percentage of power enhancement. Besides, the obtained results are compared with a regular total-cross-tied (TCT) connection, manta ray foraging optimization (MRFO), harris hawk optimizer (HHO) and particle swarm optimizer (PSO) based reconfiguration techniques. Furthermore, to demonstrate the suitability of the proposed methods, large scale PV arrays of $16\times16$ and $25\times25$ are considered and evaluated. The results reveal that MPA enhanced the PV array power by percentage of 28.6 %, 2.7 % and 5.7 % in cases of $9\times9$ , $16\times16$ and $25\times25$ PV arrays, respectively. The comprehensive comparisons endorse that MPA shows a successful shade dispersion; hence the number of multiple peaks in the PV characteristics has reduced, and high values of power have been harvested with least mean execution time in comparison with PSO, HHO and MRFO. Moreover, the Wilcoxon signed-rank test has been accomplished to confirm the reliability and applicability of the proposed approach for the PV large scale arrays as well. تلعب محطات الطاقة الشمسية الكهروضوئية واسعة النطاق دورًا أساسيًا في توفير الطلب المتزايد على الطاقة في الآونة الأخيرة. لذلك، لغرض تحقيق أعلى قوة محصودة في ظل ظروف التظليل الجزئي وكذلك حماية المصفوفة الكهروضوئية من كارثة البقعة الساخنة، يتم إنشاء استراتيجية إعادة تشكيل الكهروضوئية كإجراء فعال. يتم ذلك عن طريق إعادة توزيع الوحدات الكهروضوئية وفقًا لمستويات التظليل الخاصة بها. بدافع من هذا، قدم المؤلفون في هذه المقالة خوارزمية جديدة قائمة على السكان تُعرف باسم خوارزمية الحيوانات المفترسة البحرية (MPA) لإعادة هيكلة المصفوفة الكهروضوئية ديناميكيًا. علاوة على ذلك، يتم تقديم وظيفة موضوعية جديدة لتعزيز أداء الخوارزمية بدلاً من استخدام وظيفة الهدف المرجحة العادية في الأدبيات. يتم تقييم فعالية الخوارزميات المقترحة بناءً على وظيفة الهدف الجديدة باستخدام العديد من المقاييس مثل عامل التعبئة، وفقدان عدم التطابق، والنسبة المئوية لفقدان الطاقة، والنسبة المئوية لتعزيز الطاقة. إلى جانب ذلك، تتم مقارنة النتائج التي تم الحصول عليها مع اتصال منتظم إجمالي التعادل (TCT)، وتحسين البحث عن مانتا راي (MRFO)، ومحسن هاريس هوك (HHO) وتقنيات إعادة التكوين القائمة على محسن سرب الجسيمات (PSO). علاوة على ذلك، لإثبات ملاءمة الطرق المقترحة، يتم النظر في المصفوفات الكهروضوئية واسعة النطاق التي تبلغ 16 دولارًا\ مرات 16 دولارًا و 25 دولارًا\ مرات 25 دولارًا وتقييمها. كشفت النتائج أن MPA عززت طاقة المصفوفة الكهروضوئية بنسبة 28.6 ٪ و 2.7 ٪ و 5.7 ٪ في حالات المصفوفات الكهروضوئية 9 $\ times9 $ و 16 $\ times16 $ و 25 $\ times25 $ على التوالي. تؤيد المقارنات الشاملة أن الآلام والكروب الذهنية تظهر تشتتًا ناجحًا للظل ؛ وبالتالي انخفض عدد القمم المتعددة في الخصائص الكهروضوئية، وتم حصاد القيم العالية للقوة بأقل وقت للتنفيذ مقارنة بـ PSO و HHO و MRFO. علاوة على ذلك، تم إجراء اختبار تصنيف ويلكوكسون الموقّع لتأكيد موثوقية وقابلية تطبيق النهج المقترح للمصفوفات الكهروضوئية واسعة النطاق أيضًا.