This paper presents the performance of the 26 kVA inductive high-current transformer (HCT) during operation in the frequencies range of transformed harmonics from 50 Hz to 5 kHz. Performed research concerns the determination of the possibility of obtaining an order of the higher harmonic of a given RMS value in its distorted output current for the required RMS value of the main component and the maximum safe instantaneous value of the input voltage equal to 400 V. The results are presented for serial, serial-parallel and parallel configurations of primary and secondary windings (9 cases). Therefore, the most favourable configuration of the primary and secondary windings sections may be chosen. The tests are performed for the transformation of the distorted current containing a fundamental component and one higher harmonic of order from the 5th changed by the 5 up to the 100th. The constant 10% higher harmonic level in relation to the main component of the distorted secondary current is... [more]

Due to the insufficient consideration of medium and long-term wind power contract power in short-term dispatch, long-term planning and real-time consumption of wind power cannot be effectively undertaken, resulting in a large amount of abandoned wind power. A way to improve the wind power absorption capacity has become an urgent problem to be studied. According to the characteristics of the market and dispatching in the process of wind-fire integration construction, this paper constructs a wind power consumption model that connects the mid- and long-term transaction power decomposition and short-term dispatch. Considering the unit output characteristics and maintenance, the monthly contract electricity is decomposed into daily electricity, and the nesting of medium and long-term transactions and short-term scheduling is realized; the second stage is a short-term multi-objective optimal scheduling model considering the decomposition of contract electricity and the output of non-bidding... [more]

The production of syngas with optimal energy usage, a minimal environmental impact, and an adjustable H2/CO molar ratio is possible using tri-reforming of methane (TRM). Despite the number of studies dedicated to the TRM process, this process is still in its infancy, with many technical obstacles to overcome. Except for its kinetics and catalysts, which have been reviewed elsewhere, the TRM process is evaluated thoroughly in this work. First, feasibility studies of TRM and the TRM process are presented. Second, the impacts of various operating conditions on the rate of gas conversions, syngas production, and coke formation are discussed. Third, different reactor configurations are compared. This review then goes through the energy and energetic efficiency, economic, environmental, and safety aspects of the TRM process. Finally, a research path for the future is suggested.

The paper aims to give a universal methodology for assessing the storage capacity of a bedded rock salt formation in terms of the operational and strategic storage facilities for liquid fuels. The method assumes the development of a geological model of the analyzed rock salt formation and the determination of the salt caverns’ size and spacing and the impact of convergence on their capacity during operation. Based on this method, the paper presents calculations of the storage capacity using the example of the bedded rock salt formations in Poland and their results in the form of storage capacity maps. The maps show that the analyzed rock salt deposits’ storage capacity in northern Poland amounts to 7.1 B m3 and in the Fore-Sudetic Monocline to 10.5 B m3, in the case of strategic storage facilities. The spatial analysis of the storage capacity rasters, including determining the raster volumes and their unique values, allowed us to quantify the variability of the storage capacity in the... [more]

This paper presents an efficient and fast fault-tolerant control scheme for a bidirectional Z-source inverter (BiZSI)-fed induction-motor drive system for vehicular applications. The proposed strategy aims for the fault detection, localization and diagnosis of the proposed system during switch failures in the inverter module. Generally, power−semiconductor switch failures in inverter modules occur due to open- and short-circuit faults. An efficient modulation scheme is proposed and design specifications are thoroughly derived to obtain high voltage gains across the BiZSI network. A suitably fast detection and diagnosis scheme to isolate the faulty leg and resume the normal operation is discussed in this paper. The control scheme is provided such that the faulty leg is isolated and the motor phase is fed from a redundant leg to resume the operation. A feasible localization algorithm based on experimentally derived values and switching vectors is implemented. In addition, a fast fault di... [more]

With the rapid development of electric vehicles (EVs), many EV batteries have entered the retirement stage, leading to increasing concerns about the impact of resource recycling and environmental sustainability. Some countries have successfully applied reward−penalty and deposit−refund mechanisms in similar fields, such as lead-acid and waste portable batteries. However, whether these mechanisms are conducive to collecting waste EV batteries is unclear. This study aims to comprehensively analyze the influence of reward−penalty and deposit−refund mechanisms in EV battery collection by developing a Stackelberg game theoretical model. In the model, the recycling enterprise is the leader and the EV manufacturer is the follower. Furthermore, the total social welfare is used as the indicator to select the optimal incentive mechanisms. The results show that (1) both mechanisms could improve collection rates and recycling enterprises’ profits, though the collection rate is lower under the rewa... [more]

With the completion of the Lianghekou Reservoir, with a multiyear regulation capacity, the operation relationship of the cascade reservoirs in the Yalong River is becoming increasingly complex. In order to study an optimal operation mode of the cascade reservoirs in the Yalong River under different inflow frequencies, based on the shortcomings of the existing single reservoir operation mode and the local joint operation mode of the cascade reservoirs, this paper first proposed a global joint operation mode for the cascade reservoirs to develop the power generation potential of daily regulating reservoirs and then gave a solution method for the cascade reservoirs’ operational model based on an improved stochastic fractal search (ISFS) algorithm. Finally, taking the maximum power generation as the goal and the inflow data of five typical years as the model inputs, this paper analyzed the differences in the power generation and water abandonment results of the cascade reservoirs in the mi... [more]

In the slider-crank mechanism, where the rotational motion is transformed into the translational motion, the input torque is highly variable due to the inertial effect. The consequence of fluctuating torque is that it causes the load upon the prime mover to be inconsistent, which might likely results in higher stresses in the components, higher joint friction, and the necessity for higher driving power. In this paper, a technique of reduction of the dynamic torque and joint forces in the slider-crank mechanism using mechanical resonance is described. A comparative result of the conventional system in the process of gas compression, as a practical application example, is presented. The result shows that the utilization of resonance has the advantage of providing lower dynamic torque and rotating joint forces compared to the conventional operation. Since the compression of the air itself takes effect as a spring compression, in the gas compression process, the narrow torque and force reg... [more]

To date, along with the rapid development of urban rail transit (URT) in China, the evaluation of operational efficiency and energy efficiency has become one of the most important topics. However, the extant literature regarding the efficiency of URT at the line level and considering carbon emissions is limited. To fill the gap, an evaluation model based on slacks-based measure (SBM) data envelopment analysis (DEA) is proposed to measure the efficiencies, which is applied to 61 URT lines in China’s four megacities. The findings are summarized as follows: (1) The average operational efficiency and energy efficiency of URT lines are low, and both have great room for improvement. (2) There are significant disparities in the efficiency of URT lines in the case cities. For instance, the average operational efficiency of URT lines in Guangzhou is higher than that of other cities, while the average energy efficiency of URT lines in Shanghai is higher than that of other cities. (3) The URT lin... [more]

The current paper discusses the most recent advancements in automated vehicle (AV) certification and how existing regulations/best practices from the nuclear field helped make AVs a reality. In particular, three main pillars differentiate the newly devised certification frameworks from previous automotive regulations: the introduction of a safety management system, the adoption of in-service monitoring and reporting data logging systems, and the use of virtual testing to demonstrate the safety of the AV; a set of pillars that are also found in the nuclear practice. The argumentation is informed by relevant literature and shared experiences from the nuclear power plant and transportation fields where there are established safety practices to manage safety-critical cyber-physical systems. Although the nuclear and transportation fields might seem unrelated, strong synergies were found, including risk management approaches and operational data collection procedures, which supported the tim... [more]

Lithology is one of the critical parameters influencing drilling operations and reservoir production behavior. Well completion is another important area where facies type has a crucial influence on fracture propagation. Geological formations are highly heterogeneous systems that require extensive evaluation with sophisticated approaches. Classification of facies is a critical approach to characterizing different depositional systems. Image classification is implemented as a quick and easy method to detect different facies groups. Artificial intelligence (AI) algorithms are efficiently used to categorize geological formations in a large dataset. This study involves the classification of different facies with various supervised and unsupervised learning algorithms. The dataset for training and testing was retrieved from a digital rock database published in the data brief. The study showed that supervised algorithms provided more accurate results than unsupervised algorithms. In this stud... [more]

This review emphasizes the role and performance of versatile DC-DC converters in AC/DC and Hybrid microgrid applications, especially when solar (photo voltaic) PV is the major source. Here, the various converter topologies are compared with regard to voltage gain, component count, voltage stress, and soft switching. This study suggests the suitability of the converter based on the source type. The merits of a coupled inductor and interleaved converters in micro gird applications are elucidated. The efficiency and operating frequencies of converts for different operating modes are presented to determine the suitable converters for inductive and resistive loads. The drawbacks of converters are discussed. Finally, the mode of operation of different converts with different grid power sources and its stability and reliability issues are highlighted. In addition, the significance of the converter’s size and cost-effectiveness when choosing various PV source applications are discussed.

The variation in the thermal state of electrical energy substation equipment is normally associated with natural wear or equipment failure. This can be detected by infrared thermography, but technically it demands a long time to analyze these images. Computational analysis can allow an automated, more agile, and more efficient analysis to detect overheated regions in thermographic images. Therefore, it is necessary to segment the region of interest in the images; however, the results may diverge depending on the technique used. Thus, this article presents the improvement of four different techniques implemented in Python and applied in a substation under real operating conditions for a period of eleven months. The performance of the four methods was compared using eight statistical performance measures, and the efficiency was measured by the runtime. The segmentation results showed that the methods based on a threshold (Otsu and Histogram-Based Threshold) were fast, with processing tim... [more]

This article presents an idea of the implementation of different real load profiles for energy storage system (ESS) operation. The considered approaches are based on real long-term measurements using energy meters, the adaptation of the standard profiles defined by the distribution system operator (DSO), as well as a mix of the level of contracted power and short-term measurements. All combinations are used as electricity demand to formulate an ESS operation plan that cooperates with the PV system and the electricity market. The GAMS solver is applied to obtain optimal operation tasks of the ESS to cover different real and pseudo-real load profiles of an industrial company. Obtained results are presented using a real case study of a metallurgy company with a 317 kWp photovoltaic installation and a 200 kW ESS.

The defects in the welds of energy pipelines have significantly influenced their safe operation. The inefficient and inaccurate detection of the defects may give rise to catastrophic accidents. Ultrasonic phased array inspection is an important means of ensuring pipeline safety. The total focusing method (TFM), using ultrasonic phased arrays, has become widely used in recent years in non-destructive evaluation (NDE). However, manual defect recognition of TFM images is seen to lack accuracy and robustness, arising from deficiency of practical experience. In this paper, the automated classification of different defects from TFM images is studied with a view to facilitate inspection efficacy. By experimentally implementing the TFM approach on a bespoke specimen, the images corresponding to crack-like defects and pore-like defects were employed to investigate the effectiveness of four different machine learning models (known as Support Vector Machine, CART Decision tree, K Nearest Neighbor... [more]

Accounting for shadows on urban roads is a complex task in the operation of solar-powered electric vehicles. There have been few opportunities to compare the methods and tools for the construction of an effective shading database for urban roads. This study quantitatively investigated and compared shading matrices generated from 3D models or fisheye images. Skymaps were formed considering the geometry of nearby shading obstructions. Sun-path diagrams tracking the position of the sun by time and season were overlaid on the skymaps, and month-by-hour shading matrices were calculated. Mean squared error (MSE) was used to clarify the quantitative differences between the shading matrices. The cases were divided into A, B, and C according to the presence of buildings and trees around the survey points. Under case A (trees), case B (buildings and trees), and case C (buildings), the average MSEs between the matrices were 24.5%, 23.9%, and 2.1%, respectively. The shading matrices using either 3... [more]

The economic power-dispatching model of a multi-microgrid is comprehensively established in this paper, considering many factors, such as generation cost, discharge cost, power-purchase cost, power sales revenue, and environmental cost. To construct this model, power interactions between the two microgrids and those between the micro- and main grids are considered. Furthermore, the particle swarm optimization (PSO) algorithm is utilized to solve the economic power-dispatching model. To validate the effectiveness of the proposed model as well as the solution algorithm, a practical project case is studied and discussed. In the case study, the impact of multiple scenarios is first analyzed. Then, the system operation economic costs under different scenarios are described in detail. Moreover, according to the optimization power-dispatching results of the multi-microgrid, power interactions between the two microgrids and those between the micro- and main grids are fully discussed.

In order to accommodate more intermittent renewable energy in coal-dominated power systems, conventional thermal power plants need to improve their operational flexibility to balance the energy system at all times. However, flexible operation of coal-fired power plants could reduce energy efficiency and increase CO2 and pollutant emission, so it is important to consider environmental implications and optimize the dispatch of wind and coal power units in the system. In this paper, based on the output profile of wind power, a wind power peak (T, H) simulation model based on Gaussian distribution was established. Using a high-proportion wind power wind−coal combined base load power generation system as an example, the economical and environmentally friendly unit operation based on different wind power penetration was studied by simulation, and the decision strategy was established. Wind energy curtailment boundary was determined with power generation cost, energy consumption, CO2 and poll... [more]

Magnesium borohydride (Mg(BH4)2) is an attractive compound for solid-state hydrogen storage due to its lucratively high hydrogen densities and theoretically low operational temperature. Hydrogen release from Mg(BH4)2 occurs through several steps. The reaction intermediates formed at these steps have been extensively studied for a decade. In this work, we apply spectroscopic methods that have rarely been used in such studies to provide alternative insights into the nature of the reaction intermediates. The commercially obtained sample was decomposed in argon flow during thermogravimetric analysis combined with differential scanning calorimetry (TGA-DSC) to differentiate between the H2-desorption reaction steps. The reaction products were analyzed by powder X-ray diffraction (PXRD), near edge soft X-ray absorption spectroscopy at boron K-edge (NEXAFS), and synchrotron infrared (IR) spectroscopy in mid- and far-IR ranges (SR-FTIR). Up to 12 wt% of H2 desorption was observed in the gravime... [more]

The article analyzes the functioning of existing logistics centers in Ukraine. The logistics real estate segment was developed dynamically in Ukraine in the years before the full-scale invasion of Russia. Most logistics complexes are located in the Kyiv region, sometimes in the cities of Kharkiv, Odesa, Dnipropetrovsk and Lviv. Logistics real estate has suffered significant damage since the start of the war, and some warehouses have been completely destroyed. In order to fulfill a coordinating and integrating role in the implementation of logistics operations in the western region of Ukraine, the authors proposed the creation of a powerful regional logistics center in Lviv. The operation of the center will ensure the provision of a full range of logistics services based on the criterion of minimizing the loss of time and money. The authors proposed an algorithm for determining the optimal location of the logistics center in the region. The regional logistics center has been developed,... [more]

With the development of autopilot, the performance of intelligent vehicles is constrained by their inability to perceive blind and beyond visual range areas. Vehicle-to-infrastructure cooperative perception has become an effective method for achieving reliable and higher-level autonomous driving. A vehicle-to-infrastructure cooperative beyond visual range and non-blind area method, based on heterogeneous sensors, was proposed in this study. Firstly, a feature map receptive field enhancement module with spatial dilated convolution module (SDCM), based on spatial dilated convolution, was proposed and embedded into the YOLOv4 algorithm. The YOLOv4-SDCM algorithm with SDCM module achieved a 1.65% mAP improvement in multi-object detection performance with the BDD100K test set. Moreover, the backbone of CenterPoint was improved with the addition of self-calibrated convolutions, coordinate attention, and residual structure. The proposed Centerpoint-FE (Feature Enhancement) algorithm achieved... [more]

Experiments were conducted to investigate the heat transfer and flow characteristics of the vertical upward smooth and rifled tubes from subcritical to supercritical pressure. The distributions of wall temperature and heat transfer coefficient (HTC) were obtained, and the HTC correlations and friction resistance coefficient correlations were fitted with experimental data. In addition, the influences of heat flux and type of tube on heat transfer performance were analyzed. The research shows that heat flux has different influences on the heat transfer characteristics under different pressures. The increase in heat flux improves the heat transfer characteristics in the nucleate boiling region, yet it leads to the advance in heat transfer deterioration. However, for supercritical water, the increase in heat flux reduces the heat transfer ability. In addition, using the rifled tube not only improves the heat transfer performance, but also inhibits the occurrence of heat transfer deteriorat... [more]

Advances in medium voltage direct current (MVDC) technologies and the penetration of extended MVDC systems are still significantly hindered by the lack of adequate direct current (DC) switching equipment. The fundamentally different fault current behavior in case of a DC fault, compared to faults in alternating current (AC) systems, with regard to the characteristics and development of fault currents and their interruption make dedicated test procedures necessary. One testing approach is the application of a power-electronic buck converter (PEBC) to simulate relevant stresses on DC switching equipment during a DC fault current interruption. Since the associated requirements, especially regarding current ratings of several kiloamperes, cannot be fulfilled by using a singular PEBC, a modularization becomes necessary. However, particularly in high-power applications, the interconnection of several PEBC modules poses significant challenges. In this article, a demonstrator PEBC-based high-p... [more]

An extremely important role in the underground method of mining deposits is the type of access, which is the initial stage of the mining operations. The main feature of mineral deposits is their exhaustiveness and the inability to restore resources. This necessitates the rational management of deposit resources, especially the minimization of resource losses during exploitation. This article presents information on the mining area and methods of access the deposits. In particular, attention was paid to the advantages and disadvantages of access by means of an adit, decline, and a vertical and inclined shaft. Given the relationships among the various stages of mining works, it was found that the number of active levels depends on the volume of production and the adopted mining methods. In addition, attention was drawn to the fact that the access to deposits at increasing depth is related to the intensification of natural hazards that affect the access structure.

The trend regarding providing more distributed solutions compared to a fully centralized operation has increased the research activities conducted on the improvement of active regional communities in the power system operation in the last decades. In this study, an energy management-oriented decision-making mechanism for residential end-users based local community is proposed in a mixed-integer linear programming context. The proposed concept normally includes inflexible resiliency-sensitive load−demand activated as flexible during abnormal operating conditions, fuel cell electric vehicles (FCEVs) fed via the hydrogen provided by an electrolyzer unit connected to the residential community and capable of acting in vehicle-to-grid (V2G) mode, common energy storage and photovoltaic (PV) based distributed generation units and dispersed PV based generating options at the end-user premises. The combination of the hydrogen−electricity chain with the V2G capability of FCEVs and the resiliency-... [more]