• Energy Research

Microgrids are often considered as the solution for affordable and clean energy in the distribution sector. This article presents the small-signal stability analysis of a distributed generation unit in an autonomous microgrid operation. The purpose of the proposed strategy is to optimally improve the capacity of the power system to restore the reasonable operating condition following a small physical disturbance. The proposed strategy is the joined execution of both the modified antlion optimization algorithm (MALO) and artificial neural network (ANN), and hence it is abbreviated to MALANN. In this article, the proposed controller comprises two control loops, namely the inner current control loop and the outer power control loop. The MALO technique is incorporated to generate the dataset of possible proportional integral (PI) gain parameters. By using the accomplished dataset of MALO, the ANN is trained, and convincing estimate execution is brought out through the entire machine working condition. The proposed strategy is implemented in MATLAB/Simulink, and the results are examined with two test cases and compared with various solution techniques such as base method and ant-lion optimization. The results prove that the stability analysis is reasonably accurate, and the controller offers a reliable system's operation.

In modern dc shipboard microgrid (SMG) systems, the propulsion motors and hotel loads are always supplied through tightly regulated point of load converters, which behave as constant power loads (CPLs). The negative incremental impedance due to CPL's characteristics destabilizes the dc bus voltage of dc SMGs. Due to uncertain operating conditions of maritime ships on the sea, the dc bus voltage robust control is a crucial matter. Therefore, this paper presents a cutting-edge systematic review on advanced nonlinear control strategies to stabilize and control the CPLs in dc SMGs, such as sliding mode control, synergetic control, backstepping control, model predictive control, and passivity-based control. The latest stabilization techniques and the future trends towards an adaptive nonlinear control have been presented throughout this review. Several feedforward control-based observation and estimation techniques have been highlighted. The stability analysis and stability challenges of dc SMGs are also discussed.

The repercussions of high levels of environmental pollution coupled with the low reserves and increased costs of traditional energy sources have led to the widespread adaptation of wind energy worldwide. However, the expanded use of wind energy is accompanied by major challenges for electric grid operators due to the difficulty of controlling and forecasting the production of wind energy. The development of methods for addressing these problems has therefore attracted the interest of numerous researchers. This paper presents an innovative method for assessing wind speed in different and widely spaced locations. The new method uses wind speed data from multiple sites as a single package that preserves the characteristics of the correlations among those sites. Powerful Waikato Environment for Knowledge Analysis (Weka) machine learning software has been employed for supporting data preprocessing, clustering, classification, visualization, and feature selection and for using a standard algorithm to construct decision trees according to a training set. The resultant arrangement of the sites according to likely wind energy productivity facilitates enhanced decisions related to the potential for the effective operation of wind energy farms at the sites. The proposed method is anticipated to provide network operators with an understanding of the possible productivity of each site, thus facilitating their optimal management of network operations. The results are also expected to benefit investors interested in establishing profitable projects at those locations.

This article presents a novel quadruple boost inverter (QBI) with an integrated boost stage that comprises an inductor, a capacitor, a switch, and an input source. The inductor on the input side limits the inrush current and also the capacitor charging current ripples. The QBI topology comprises a dc source, an input inductor, nine switches, three diodes, and capacitors. This produces a nine-level waveform, which reduces the need for additional filters such as inductors and capacitors. The proposed QBI is elementary, compact, and needs fewer components than existing nine levels inverter. Compared to the typical triangular carrier-based sinusoidal pulse width modulation, the newly developed parabolic level-shifted carrier has a much greater RMS value. Another advantage of the proposed topology is extension for generating higher voltage levels without increment in the blocking voltage across the switches. This makes the topology ideal for medium voltage high power applications. The output voltage has been determined in terms of selection, sizing, and expression. The proposed QBI is compared to existing similar nine-level inverters in order to assess its efficacy. The experiment is performed on a laboratory prototype to state the practical feasibility of QBI topology for the inductive load, variation in input, load, and modulation index.

Les constructeurs automobiles se concentrent sur des technologies récentes telles que la croissance de la chaîne de traction des véhicules à hydrogène (H2) et à pile à combustible (FC) pour améliorer l'efficacité du Tank-to-Wheel (TTW). Avantages, réduction des coûts, respect de l'environnement, capacité zéro émission et haute puissance, etc. Dans la chaîne de traction des véhicules à pile à combustible, les convertisseurs de puissance CC-CC jouent un rôle essentiel pour augmenter la tension de l'empilement de piles à combustible. Par conséquent, satisfaire la demande du moteur et de la transmission dans les véhicules. Plusieurs topologies de convertisseurs CC-CC ont été proposées pour diverses applications automobiles telles que les véhicules hybrides alimentés par pile à combustible, batterie et énergie renouvelable, etc. Dans la plupart des cas, les convertisseurs de puissance CC-CC sont des solutions viables et rentables pour FC-VPT avec une taille réduite et une efficacité accrue. Cet article décrit l'état de l'art dans les topologies de convertisseur de puissance multi-étage (MPC) DC-DC non isolé unidirectionnel pour l'application FC-VPT. Le document présentait l'examen complet, la comparaison de différentes topologies et indiquait l'adéquation pour différentes applications de véhicules. Cet article aborde également les applications DC-DC MPC plus spécifiques au groupe motopropulseur d'un petit véhicule à de gros véhicules (bus, camions, etc.). En outre, les avantages et les inconvénients soulignés avec les caractéristiques importantes pour les convertisseurs. Enfin, la classification des convertisseurs DC-DC, ses défis et ses applications pour la technologie FC sont présentés dans l'article de synthèse comme étant à la pointe de la recherche. Las compañías automotrices se están centrando en tecnologías recientes como el crecimiento del tren de potencia vehicular (VPT) de hidrógeno (H2) y pila de combustible (FC) para mejorar la eficiencia del tanque a la rueda (TTW). Beneficios, menor coste, respetuoso con el medio ambiente, cero emisiones y capacidad de alta potencia, etc. En el tren de potencia de los vehículos de pila de combustible, los convertidores de potencia CC-CC desempeñan un papel vital para aumentar el voltaje de la pila de pila de combustible. Por lo tanto, satisfaga la demanda del motor y la transmisión en los vehículos. Varias topologías de convertidores CC-CC se han propuesto para diversas aplicaciones vehiculares, como celdas de combustible, baterías y vehículos híbridos alimentados con energía renovable, etc. En la mayoría de los casos, los convertidores de potencia CC-CC son soluciones viables y rentables para FC-VPT con un tamaño reducido y una mayor eficiencia. Este artículo describe el estado de la técnica en topologías de convertidor de potencia multietapa (MPC) DC-DC no aislado unidireccional para la aplicación FC-VPT. El documento presentó la revisión exhaustiva, la comparación de diferentes topologías y estableció la idoneidad para diferentes aplicaciones vehiculares. Este artículo también analiza las aplicaciones DC-DC MPC más específicas para el tren de potencia de un vehículo pequeño a vehículos grandes (autobuses, camiones, etc.). Además, las ventajas y desventajas señaladas con las características destacadas para los convertidores. Finalmente, la clasificación de los convertidores DC-DC, sus desafíos y aplicaciones para la tecnología FC se presenta en el artículo de revisión como estado del arte en investigación. The automobile companies are focusing on recent technologies such as growing Hydrogen (H2) and Fuel Cell (FC) Vehicular Power Train (VPT) to improve the Tank-To-Wheel (TTW) efficiency. Benefits, the lower cost, `Eco' friendly, zero-emission and high-power capacity, etc. In the power train of fuel cell vehicles, the DC-DC power converters play a vital role to boost the fuel cell stack voltage. Hence, satisfy the demand of the motor and transmission in the vehicles. Several DC-DC converter topologies have proposed for various vehicular applications like fuel cell, battery, and renewable energy fed hybrid vehicles etc. Most cases, the DC-DC power converters are viable and cost-effective solutions for FC-VPT with reduced size and increased efficiency. This article describes the state-of-the-art in unidirectional non-isolated DC-DC Multistage Power Converter (MPC) topologies for FC-VPT application. The paper presented the comprehensive review, comparison of different topologies and stated the suitability for different vehicular applications. This article also discusses the DC-DC MPC applications more specific to the power train of a small vehicle to large vehicles (bus, trucks etc.). Further, the advantages and disadvantages pointed out with the prominent features for converters. Finally, the classification of the DC-DC converters, its challenges, and applications for FC technology is presented in the review article as state-of-the-art in research. تركز شركات السيارات على التقنيات الحديثة مثل زراعة الهيدروجين (H2) و خلايا الوقود (FC) قطار توليد الطاقة للمركبات (VPT) لتحسين كفاءة Tank - To - Wheel (TTW). الفوائد، والتكلفة الأقل، والقدرة الصديقة للبيئة، والانبعاثات الصفرية، والطاقة العالية، وما إلى ذلك. في مجموعة نقل الحركة لمركبات خلايا الوقود، تلعب محولات الطاقة DC - DC دورًا حيويًا في تعزيز جهد مكدس خلايا الوقود. وبالتالي، تلبية طلب المحرك وناقل الحركة في المركبات. اقترحت العديد من طوبولوجيا محول DC - DC لمختلف تطبيقات المركبات مثل خلايا الوقود والبطارية والمركبات الهجينة التي تغذيها الطاقة المتجددة وما إلى ذلك. في معظم الحالات، تعد محولات الطاقة DC - DC حلولًا قابلة للتطبيق وفعالة من حيث التكلفة لـ FC - VPT مع تقليل الحجم وزيادة الكفاءة. تصف هذه المقالة أحدث ما توصلت إليه طبولوجيا محول الطاقة متعدد المراحل (MPC) أحادي الاتجاه وغير المعزول DC - DC لتطبيق FC - VPT. قدمت الورقة المراجعة الشاملة ومقارنة الطوبولوجيا المختلفة وذكرت مدى ملاءمة تطبيقات المركبات المختلفة. تناقش هذه المقالة أيضًا تطبيقات DC - DC MPC الأكثر تحديدًا لمجموعة نقل الحركة لمركبة صغيرة إلى المركبات الكبيرة (الحافلات والشاحنات وما إلى ذلك). علاوة على ذلك، أشارت المزايا والعيوب إلى الميزات البارزة للمحولات. أخيرًا، يتم تقديم تصنيف محولات DC - DC وتحدياتها وتطبيقاتها لتكنولوجيا FC في مقالة المراجعة كأحدث ما توصلت إليه الأبحاث.

The presence of stray capacitance in ZnO (Zinc Oxide) surge arresters causes hurdles in arrester operation and non-uniform voltage distribution along the arrester column, especially for High Voltage (HV) and Extra high voltage (EHV) applications. Since the magnitude of stray capacitance is directly proportional to the arrester height; the shortening of surge arresters is a preeminent method to enhance the arrester performance and voltage distribution. Particularly, this stray capacitive effect delays the arrester operation from in-action to action mode, especially against very fast surges. Moreover, the shortening of the arrester column improves the voltage distribution and hence the electric field varies between the stacks. Therefore, this research work focuses on the preparation of two new high gradient arrester materials doping with rare earth oxides. The microstructures of the newly developed materials are analyzed. It is found that there is a reduction of grain sizes and an increase of voltage gradients in the newly developed arrester materials. From this, the height requirement per unit is estimated and compared with the conventional ZnO arrester. Using these high gradient materials, the reduction of height and compactness of the arrester assembly may be achieved greatly. Thus, the developed ZnO surge arrester with high gradient materials enhances the arrester behavior with the attendant improvement of voltage distribution due to its reduced height and stray effect.

In remote locations such as villages, islands and hilly areas, there is a possibility of frequent power failures, voltage drops or power fluctuations due to grid-side faults. Grid-connected renewable energy systems or micro-grid systems are preferable for such remote locations to meet the local critical load requirements during grid-side failures. In renewable energy systems, solar photovoltaic (PV) power systems are accessible and hybrid PV-battery systems or energy storage systems (ESS) are more capable of providing uninterruptible power to the local critical loads during grid-side faults. This energy storage system also improves the system dynamics during power fluctuations. In present work, a PV-battery hybrid system with DC-side coupling is considered, and a power balancing control (PBC) is proposed to transfer the power to grid/load and the battery. In this system, a solar power conditioning system (PCS) acts as an interface across PV source, battery and the load/central grid. With the proposed PBC technique, the system can operate in following operational modes: (a) PCS can be able to work in grid-connected mode during regular operation; (b) PCS can be able to charge the batteries and (c) PCS can be able to operate in standalone mode during grid side faults and deliver power to the local loads. The proposed controls are explained, and the system response during transient and steady-state conditions is described. With the help of controller-in-loop simulation results, the proposed power balancing controls are validated, for both off-grid and on-grid conditions.