Search Results (45,088)

Electrical machines are prone to various faults and require constant monitoring to ensure safe and dependable functioning. A potential fault in electrical machinery results in unscheduled downtime, necessitating the prompt assessment of any abnormal circumstances in rotating electrical machines. This paper provides an in-depth analysis as well as the most recent trends in the application of condition monitoring and fault detection techniques in the disciplines of electrical machinery. It first investigates the evolution of traditional monitoring techniques, followed by signal-based techniques such as spectrum, vibration, and temperature analysis, and the most recent trends in its signal processing techniques for assessing faults. Then, it investigates and details the implementation and evolution of modern approaches that employ intelligence-based techniques such as neural networks and support vector machines. All these applicable and state-of-art techniques in condition monitoring and fault diagnosis aid in predictive maintenance and identification and have the highly reliable operation of a motor drive system. Furthermore, this paper focuses on the possible transformational impact of electrical machine condition monitoring by thoroughly analyzing each of the monitoring techniques, their corresponding pros and cons, their approaches, and their applicability. It offers strong and useful insights into proactive maintenance measures, improved operating efficiency, and specific recommendations for future applications in the field of diagnostics. Full article

Hydrogen as an energy vector is going to play an important role in the global energy mix. On the other hand, wastewater management has become a worldwide concern, as urban settlements have been considerably increasing for decades. Consequently, biodigestion to produce biogas (rich in methane) in water treatment plants could be an interesting starting point to obtain a valuable gas that can be converted into hydrogen through steam reforming. The aim of this work was to review the main aspects concerning steam reforming of biogas from wastewater treatment plants. For this purpose, the whole chain, from water treatment to hydrogen production and purification, was considered, paying attention to the main challenges and new technologies for its optimization. Thus, a wide range of possibilities is offered, from direct energy use of syngas to high purification of hydrogen (mainly through pressure swing adsorption or membrane reactors), presenting advantages and disadvantages. In any case, the role of catalysts seems to be essential, and aspects such as hydrogen sulfide and coke deposition control should be addressed. In conclusion, biogas steam reforming applied to wastewater treatment plants is a reality, with serious possibilities for its global implementation at the industrial level, according to techno-economic assessment. Full article

Lightning is a modern societal problem that continues to increase in line with technological growth. Today’s infrastructure is very vulnerable to disturbances caused by weather conditions. The most influential weather phenomenon in this regard is the weather produced by cumulonimbus (CB) clouds. Almost every year, tanks and refineries in Indonesia explode due to lightning strikes. Furthermore, there have been several instances of outages in transmission and distribution lines, as well as lightning-related fatalities in mining areas. Lightning characteristics are widely used as important data for designing lightning protection systems. However, in Indonesia, there is still a need to obtain proper lightning characteristic data. Indonesia is a maritime country located in the tropics, making its geographical conditions highly conducive to the formation of cumulonimbus (CB) clouds. Therefore, this paper presents direct lightning peak-current measurements using magnetic tape, which has been installed in several provinces in Indonesia. The paper reports the local lightning characteristics for these provinces and presents a method for obtaining lightning data. To efficiently collect lightning data on a large scale, we propose a measurement system consisting of a lightning-event counter and magnetic tape. While magnetic tape has been widely used in laboratory testing, this research discusses its application and measurement results in natural lightning conditions in the field. The novel lightning characteristics obtained for several provinces in Indonesia are expected to assist professionals in designing lightning protection systems that match the local lightning characteristics, ultimately minimizing the impact of lightning damage. Full article

This paper presents a semi-analytical method for determining the distribution of the thermal field in a system of two parallel round conductors, taking into account the skin and proximity effects. The method of a suitably constructed Green’s function was applied to find an analytical expression for the eigenfunctions describing the temperature distributions. In turn, the relevant integrals, which cannot be determined analytically, were calculated numerically. The foundation of the method is the knowledge of the current density distribution in the conductors. As a result, the steady-state distribution of the temperature field in the conductors for various parameter values can be determined. The obtained numerical results were positively verified using the finite element method. Using the developed method, the share of skin and proximity effects in the temperature rise and steady-state current rating was evaluated. Closed analytical formulas were obtained for the AC case with the skin effect taken into account. When the skin depth is smaller than the wire radius, the skin effect has quite a large impact on the conductor temperature. The impact of the proximity effect is much smaller but clearly noticeable when the distance between the wires is smaller than five times the wire radius. In addition, the influence of the value of the heat transfer coefficient on the thermal field of the conductors was also examined. Full article

Climate change and transition risks have become major issues concerning the sustainable development of human society today. And the stranded fossil energy assets generated in this context are gradually becoming an important factor affecting corporate development and the stability of financial markets. Based on the data of China’s A-share listed companies in the high-carbon industry from 1998 to 2021, a two-way fixed-effects model is used to study the determinants of corporate fossil energy asset impairment. Furthermore, a “two-stage estimation approach” is used to measure the risk of stranding corporate fossil energy assets The results show that: (1) climate transition risks are a significant cause of stranded corporate fossil energy assets; (2) the stranded risk of Chinese companies’ fossil energy assets has been oscillating upward over the past two decades; (3) the stranded risk has increased significantly after the “double carbon” target. Based on the above conclusions, this paper puts forward relevant suggestions from both government and enterprise perspectives. Full article

The safe evacuation of residents near a nuclear power plant during a nuclear accident is vital for emergency response planning. To tackle this challenge, considering the dynamic dispersion of radioactive materials in the atmosphere and its impact on evacuation routes under different meteorological conditions is crucial. This paper develops a dynamic dose-based emergency evacuation model (DDEEM), which is an efficient and optimized nuclear accident evacuation model based on dynamic radiological dose calculation, utilizing an improved A* algorithm to determine optimal evacuation routes. The DDEEM takes into account the influence of radiological plume dispersion and path selection on evacuation effectiveness. This study employs the DDEEM to assess radiological consequences and evacuation strategies for students residing 5 $\mathrm{k}\mathrm{m}$ from a Chinese nuclear power plant. Under various meteorological conditions, including the three typical meteorological conditions, random ordered and random unordered meteorological sequences, optimal routes obtained through the DDEEM effectively reduce radiological dose exposure and mitigate radiation hazards. The results indicate that all evacuation paths generated by the DDEEM have a maximum dose of less than $1 \mathrm{m}\mathrm{S}\mathrm{v}$. Through simulations, the model’s effectiveness and reliability in dynamic radiological environments in terms of radiological consequences and evacuation analysis is verified. The research provides valuable insights and a practical tool for nuclear power plant emergency decision-making, enhancing emergency management capabilities during nuclear accidents. The DDEEM offers crucial technical support and a solid foundation for developing effective emergency response strategies. Full article

Position control algorithms can be classified into two groups: point-to-point control and continuous path control. For point-to-point control implemented in programmable logic controllers, the speed setpoint is mostly the only setpoint transmitted to the industrial converter. Incorrect settings of the position controller in PLC may lead to position overshoot or oscillations, which are unacceptable in position control applications. The speed control structure in the industrial converter usually has a fixed structure which does not allow the implementation of advanced speed controller. Moreover, standard library blocks for position control encounter difficulties in diagnostics and tuning. To address these limitations, this paper proposes a novel solution for position control that achieves time-optimal speed trajectory during acceleration and enhanced capabilities during deceleration. The proposed controller was verified by simulations of positioning of zinc ingot feeder unit drive and compared with a standard P-controller. Experimental results confirmed the performance of the proposed controller with the industrial application of a feeder unit. Full article

The intercooler is a crucial component of the rich gas compressor. Due to the shortcomings of the conventional segmental baffle intercooler, an optimization design of the novel industrial-grade twisted-elliptic-tube intercooler is proposed. This study aims to compare the heat-transfer performance of these two types of intercoolers in a delayed coking unit at Sinopec. During the plant revamp operation, the original segmental baffle intercooler was replaced by the novel twisted-elliptic-tube intercooler. Experimental determination and comparison analysis of the industrial locale operation of the two types of intercoolers before and after the revamps were conducted. The evaluation results show that the novel twisted-elliptic-tube intercooler has a higher cooling capacity, with a 13.2% increase, compared to the conventional intercooler. Under identical operating conditions, the overall heat-transfer coefficients increase by 87.8%. Moreover, the heat-transfer area and gas pressure drop decrease by 37.4% and 36.9%, respectively. The tube bundles’ vibration and loud noise problems of the old intercooler are eliminated. The average exit temperature of the enriched gas that requires cooling is 38.4 °C, which is 7.3 °C lower than that of the conventional intercooler. These outcomes indicate that utilizing this innovative twisted-elliptic-tube heat exchanger can provide substantial advantages in terms of high heat-transfer efficiency and exceptional anti-vibration performance. Full article

The evaluation of the energy efficiency of vehicles in operating conditions is used to solve management and control tasks in intelligent transport systems. The modern world fleet is characterized by an increase in the share of vehicles with alternative power plants (hybrid, electric, and hydrogen fuel cells). At the same time, vehicles with conventional power plants (internal combustion engines) remain in operation. A wide range of modern power plants determines the relevance of studying the advantages and limitations of existing methods of evaluating the vehicle energy efficiency, delineating the application scope and highlighting promising directions for their further development. The article systematizes the methods of evaluation and management of the energy efficiency of vehicles with conventional and alternative power plants. Special attention is paid to the assessment of energy consumption per unit of transport work at the stage of vehicle operation, taking into account various operational factors. The concept of a 3D morphological model of the transport system for evaluating the energy efficiency of vehicles is presented. An algorithm for the optimization of the current transport system configuration according to the criterion of an increase in the energy efficiency indicator is given. Full article

Renewable energy penetration and distributed generation are key for the transition towards more sustainable societies, but they impose a substantial challenge in terms of matching generation with demand due to the intermittent and unpredictable nature of some of these renewable energy sources. Thus, the role of energy storage in today’s and future electricity markets is undisputed. Batteries stand out among the different alternatives for energy storage. The R&D effort into different battery chemistries contributes to reducing the investment associated with battery systems. However, optimizing their operation according to the users’ and the electricity markets’ needs is the turning point to finally make these systems attractive. This review delves into the topic of battery management systems from a battery-technology-independent perspective, and it also explores more fundamental but related aspects, such as battery modeling or state estimation. The techno-economic part of battery energy storage systems is also covered in this document to understand their real potential and viability. Full article

The current study investigates economic expectations and socio-psychological factors influencing individuals’ residential photovoltaic (RPV) adoption intentions in Thailand. The theory of planned behavior (TPB) and the diffusion of innovation theory provide a framework for our predictor selection. We obtained the data from a nationwide survey on electricity prosumer infrastructure. RPV non-users (N = 760) were asked to rate their RPV knowledge, attitudes, perceived behavioral controls (PBCs), norms, and innovativeness. They then read scenarios describing the current RPV installation cost and payback rate. They rated their adoption intention and specified their intended system capacity, affordable installation cost, and desirable payback period. The gaps between the actual and desired installation costs and the internal rate of return were calculated. These economic expectation gaps, attitudes based on financial benefits, PBC based on perceived financial barriers, social norms, and innovativeness significantly predicted the adoption intention. On the other hand, perceived knowledge, attitudes based on environmental and image benefits, and PBC based on anticipated troubles and inconveniences failed to predict intention. The implications of the TPB model for RPV adoption were discussed. Full article

The maintenance of electrical grids is crucial for improving their reliability, performance, and cost-effectiveness. It involves employing various strategies to ensure smooth operation and address potential issues. With the advancement of digital technologies, utilizing time-series prediction has emerged as a valuable approach to enhance maintenance practices in electrical systems. The utilization of various recorded data from electrical grid components plays a crucial role in digitally enabled maintenance. However, the comprehensive exploration of time-series data prediction for maintenance is still lacking. This review paper extensively explores different time series that can be utilized to support maintenance efforts in electrical grids with regard to different maintenance strategies and grid components. The digitization of the electrical grids has enabled the collection of diverse time-series data from various network components. In this context, the paper provides an overview of how these time-series and historical-fault data can be utilized for maintenance purposes in electrical grids. Various maintenance levels and time series used for maintenance purposes in different components of the electrical grid are presented. Full article

To achieve carbon neutrality, many countries and regions are making efforts to promote the commercialization of greenhouse gas (GHG) mitigation technologies using emissions trading systems (ETSs). Accurate predictions of when the cost of GHG reduction technologies will become competitive below carbon prices could be invaluable to engineers and policy makers. In this study, carbon price movement in the EU-ETS was analyzed using a geometric Brownian motion (GBM) model. Using daily price data for the last 10 years, it tested whether the price pattern of the latter three years could be predicted by applying the first seven years of data to the GBM model. The results showed that the GBM model could well predict the upper and lower bounds of the actual carbon price. Based on the acceptable predictability of the GBM model, simulations were performed using carbon price data over the last decade, showing that carbon prices would reach around 200 EUR/tCO₂ by the start of 2026. This is higher than the cost of CO₂ avoided evaluated from the costs of commercial-scale carbon capture facilities for coal-fired power plants. This means that carbon capture technologies in the coal-fired power sector could become economically competitive within the next several years. Full article

The converter valve is the core equipment of flexible DC transmission, but it has been severely damaged in previous earthquakes. Therefore, the seismic performance of its structure has a significant impact on the safety and reliability of power transmission. To study the seismic performance of ±500 kV flexible DC converter valves and identify weak links in the supporting valve tower, this article first established a refined finite-element model of a valve tower based on its physical structure; then modal analysis on the valve tower was conducted; finally, time-domain analysis of the valve tower under three seismic excitations, namely Wenchuan, EI Centro, and artificial, was conducted, and the equivalent stress and directional displacement cloud maps of the key parts of the valve tower were obtained. The research results indicate that the dynamic characteristics of the valve tower are relatively complex, with low fundamental frequency and diverse natural vibration modes. Under earthquake action, the predominant frequency of EI Centro waves is close to the fundamental frequency of the valve tower, which is prone to resonance and causes significant damage to the valve structure. The improved design of the valve tower meets the seismic strength requirements of level 8 seismic intensity. Full article

A dual-axis solar tracking system with a novel and simple structure was designed and constructed, as documented in this paper. The photoelectric method was utilized to perform the tracking. The solar radiation values of the designed system and a fixed panel system were theoretically estimated and compared, showing that the proposed system is more efficient in collecting solar energy than a fixed solar panel with a 30° tilted fixed surface facing south. The experimental results verified the validity of the prediction as well as the efficiency of the proposed solar tracking system. In a comparison of the data obtained from the measurements, 24.6% more energy was seen to have been obtained in the dual-axis solar tracking system compared to the fixed system. This study possesses potential value in small- and medium-sized photovoltaic applications. Full article