The paper proposed an innovative predictive maintenance system, designated to monitor and diagnose critical electrical equipment (generally large power electric motors) within industrial electrical installations. A smart and minimally invasive system is designed and developed. Its scope is to evaluate continuously the essential operating parameters (electrical, thermal, and mechanical) of the investigated equipment. It manages to report the deviations of inspected machine operating parameters values from the rated ones. The system also suggests the potential cause of these abnormal variations along with possible means (if the defect is identified in a database, constantly updated with each appearance of a malfunction). The developed maintenance device generates an operating report of the analyzed equipment, in which the values of power quality and energy indicators are computed and interpreted. Additionally, real-time remote transmission of analyzed data is facilitated, making them acc... [more]

In recent years, the usage potential of alternative energy sources has been gaining importance to increase the efficiency of ships within the scope of the obligations brought by international maritime regulations. The possibility of using alternative energy sources such as solar energy, wind energy, fuel cells, and waste heat recovery technologies on ships has been evaluated in the literature. Today, ships also have waste heat recovery systems as standard equipment for this purpose, and this method is suitable for thermoelectric generators that generate electricity from temperature differences on shipboards. This article aims to review the thermal technologies for the power generation of shipboards. By conducting a case study, an energy efficiency increase was obtained when functional areas were selected on a practical ship, and the effect of this efficiency increase on emissions was examined. As a result of the research, it was discovered that thermoelectric generators increased onboa... [more]

As many new devices and factors, such as renewable energy sources, energy storage (ESs), electric vehicles (EVs), and demand response (DR), flood into the distribution network, the characteristics of the distribution network are becoming complicated and diversified. In this study, a two-layer collaborative optimized operation model for the multi-character distribution network considering multiple uncertain factors is proposed to achieve optimal dispatching of ES and EV and obtain the optimal grid structure of the distribution network. Based on basic device models of distribution network, the upper layer distribution network reconfiguration (DNR) model is established and solved by the particle swarm optimization (PSO) based on the Pareto optimality and the Prim algorithm. Then, the lower layer optimal dispatching model of ES and EV is established and solved by the binary PSO. The upper layer model and the lower layer model are integrated to form the collaborative optimized operation mod... [more]

The continuity of gas-supply service is a major concern for all gas-supply operators. A safety review of a gas-supply system could help to mitigate the potential repercussions of supply disruptions. Disruptions occur at random due to systemic failures in gas distribution networks. Assessing the operational safety of gas distribution networks is challenging and complex, especially when operational data are limited or associated with high uncertainty. This paper focuses on gas leak incidents. Natural gas leaks disrupt the production process and endanger the ecosystem. Mechanically originated damage in pipelines is found to be the major cause of leaks, according to our investigations. This paper proposes a three-parameter risk matrix to be used in the safety analysis of gas-supply systems. This paper then raises the possibility of using grey-system theory. Grey-system theory has been used to overcome the limitations of the conventional matrix method. This choice is motivated by two facts:... [more]

The paper presents the results of sociological qualitative research on safety management in work organization. The focus was on how to adapt the workforce to the sanitary regime during the time of the COVID-19 pandemic in the lignite mining and energy sector in the Bełchatów poviat (Łódź voivodeship, Poland). The study aimed to identify the dimensions of safety and the work culture created in crisis conditions as perceived by workers. Based on the conducted analysis, the process of adapting employees to the new rules of work organization was reported, including the transition from fear and anxiety to control over threats and negative emotions. The essence of the research was to support institutional memory to consolidate the existing knowledge and use it in the future.

This paper proposes a prediction-driven sequential optimization methodology for joint decision-making problems of production-sales-stock in refined oil enterprises. In the proposed prediction-driven sequential optimization methodology, three dynamic nonlinear programming models are first constructed to model the production-sales-stock decision-making problems in refined oil enterprises. Then, the analytical solutions to sequential optimization for production-sales-stock decision-making issues are presented by using the inverse inference method in dynamic programming. Finally, the impact of price and demand prediction of refined oil products on sequential optimization for production-sales-stock decision-making are analyzed using a numerical analysis method. Numerical results demonstrated the significant impact of forecasting results of price and demand of refined oil products on sequential optimization decision-making, indicating that the prediction-driven sequential optimization method... [more]

With the further development and wide application of wireless technology in 6G, people are increasingly inseparable from wireless devices, from the ground to the air. The power consumption and service life of devices have become an urgent problem to be solved. In this paper, the energy harvesting relaying system based on the power splitting method with unidirectional DF half-duplex and full-duplex relay is proposed. The relay node is powered by itself through energy harvesting. Specifically, we analyze the system capacity, and the formula of system outage probability is also obtained. Simulation results show the performance of the half-duplex and full-duplex system. With a smaller power splitting factor, more energy is harvested, the outage probability is lower, and the capacity is higher.

Networked microgrid (NMG) is a novel conceptual paradigm that can bring multiple advantages to the distributed system. Increasing renewable energy utilization, reliability and efficiency of system operation and flexibility of energy sharing amongst several microgrids (MGs) are some specific privileges of NMG. In this paper, residential MGs, commercial MGs, and industrial MGs are considered as a community of NMG. The loads’ profiles are split into multiple sections to evaluate the maximum load demand (MLD). Based on the optimal operation of each MG, the operating reserve (OR) of the MGs is calculated for each section. Then, the self-organizing map as a supervised and a k-means algorithm as an unsupervised learning clustering method is utilized to cluster the MGs and effective energy-sharing. The clustering is based on the maximum load demand of MGs and the operating reserve of dispatchable energy sources, and the goal is to provide a more efficient system with high reliability. Eventual... [more]

Today’s power distribution networks are predicted to incorporate more Power Electronics (PE)-based power conversion systems, widely acknowledged as harmonic sources. Concerns about power harmonic severity in the distribution networks can arise, especially with the growing numbers of Medium Voltage Direct Current (MVDC) systems, which are also facilitated by such power converters. Yet, an accurate harmonic model of the MVDC converter is required to investigate its harmonic emissions, propagations, effects, and solutions in today’s distribution networks. This article is devoted to the development of a detailed model of a cascaded Neutral Point-Clamped (NPC)-based MVDC converter for accurate harmonic analysis studies. An appropriate control system with a simple Proportional Integral (PI) controller tuned using the loop-shaping technique is developed. An interleaved Sinusoidal Pulse-Width Modulation (SPWM) scheme aiming to improve the harmonic performance of such an application is introduc... [more]

Electric springs (ESs) are novel electric-power devices that alleviate power-quality problems such as voltage fluctuations induced by grid access to renewable energy resources. However, with the continuous increase of uncertain factors such as parameter perturbation and external disturbance, the environment becomes more complicated, so traditional linear controllers for ESs are finding it increasingly difficult to meet the control requirements due to narrow stability regions, low precision, and poor robustness. To overcome this problem, we propose herein a control method that combines adaptive control and sliding-mode control and apply it to ESs. First, an inexact model of the ES system was established and analyzed. Next, an ES control system was designed based on adaptive sliding-mode control, and then the asymptotic stability of the closed-loop system is proven. Finally, the proposed control system was verified through a MATLAB simulation. The results show that adaptive sliding-mode... [more]

The increasing Photovoltaic (PV) penetration in residential Low Voltage (LV) networks is likely to result in a voltage rise problem. One of the potential solutions to deal with this problem is to adopt a distribution transformer fitted with an On-Load Tap Changer (OLTC). The control of the OLTC in response to local measurements reduces the need for expensive communication channels and remote measuring devices. However, this requires developing an advanced decision-making algorithm to estimate the existence of voltage issues and define the best set point of the OLTC. This paper presents a decentralized data-driven control approach to operate the OLTC using local measurements at a distribution transformer (i.e., active power and voltage at the secondary side of the transformer). To do so, Monte Carlo simulations are utilized offline to produce a comprehensive dataset of power flows throughout the distribution transformer and customers’ voltages for different PV penetrations. By the appli... [more]

With the large amounts of small capacity and heterogeneous distributed electricity units connected to the distribution power network, there exist increasingly complex management challenges. In this paper, a new management scheme that can classify and divide the distributed units according to their adjustable characteristics is proposed, which consequently forms an effective collection of fragmented adjustable ability and promotes the utilization of micropower resources. Inspired by the social division of labor in the biological community, the approach is based on a logical aggregation with the division of labor. A feature extraction method was acquired on the basis of the daily output curve, which reduces the data dimension and, subsequently, clusters the output feature points by the K-means algorithm. The simulation is performed by taking the measured output curve of low voltage distributed units on the low voltage side. The experimental results analyze the characteristics of seven cl... [more]

In this article, issues related to electromagnetic compatibility and energy/power quality for a laptop are addressed. Power quality problems are outlined. Testing frameworks (developed by authors) are presented and discussed for a laptop when two different sampling frequencies are used: 80 kHz and 19.2 kHz. Waveforms corresponding to the voltage across the laptop’s terminals and current absorbed by it were acquired. Recordings and numerical processing, based on original software using Fast Fourier Transform, are discussed, and the analysis of waveforms in both cases is performed. Various power quality indices were calculated. Theoretical and practical aspects related to the determination of power quantities, power flows, and power factor are presented. Some conclusions concerning different ranges of frequencies are presented, along with some considerations for power quality problems. Tests for conducted emissions (single phase and neutral wire respectively) and for the radiated emissio... [more]

Ukrainian electricity production sector is in a critical situation. It is necessary to increase the coal production to ensure the continuity of electricity production. In this paper, an analysis of coal mining in western Donbas, Ukraine, was presented. The crucial thing is to increase coal production in this region. The new calculation schemes were proposed to increase coal extraction in Donbas mines. The coal pillar parameters, which are necessary for the effective control of the rock pressure caused by the stooping, were substantiated. The obtained parameters for the coal pillars will allow extracting more coal, safely and quickly dismantling the mechanized complex and effectively protecting the ongoing mine work. The case study helps determine the coal losses because of pillar leaving and to improve the stability of the main haulage roads located in the zone of the stooping effect as well as to achieve additional coal production in the mine. Such a technological solution allows to e... [more]

A dual-mode hybrid step-up circuit for electromagnetic energy harvesting (EVEH) is proposed in this paper, with the merits of continuous output power delivery with and without external vibrations, simple architecture, and no need for extra circuits to start up. The proposed hybrid converter combines a multi-stage voltage multiplier (VM) with a boost regulator, which utilizes the winding inductance of the electromagnetic energy harvester as a boost inductor. With external vibration, the proposed circuit powers the load and stores energy in the super-capacitor through VM mode. When external vibration disappears, it automatically switches to boost mode and powers the load using the energy stored in the supercapacitor. For hybrid mode operation, the number of VM stages is optimized considering the following three aspects: sufficient voltage gains when vibration is on, time durations to provide constant power when vibration is off for as long as possible, and low losses at VM stage. A GaN-b... [more]

This paper proposes a swing-magnet-type generator that utilizes environment vibration for energy harvesting applications. This device consisted of a liquid, a swing magnet with a float, and a coil, and it was expected to generate electricity using the minute vibration of a bicycle. The vibration of the wide frequency band of the bicycle was converted into a vibration of a low-frequency mover. The yoke size of the permanent magnet affected the linkage flux and swing characteristics. Therefore, we verified the effect of the mover characteristics on the swing moment by structural simulations and vibration experiments using a linear motor. The yoke size changed the torque, which affected the resonant frequency of the swing. The magnetic-field analysis revealed the effect on the flux linkage in the yoke. The output voltage of the generator in the bicycle was 2.1 V, which could power a light-emitting diode.

The protection against the unintentional islanding of Grid-Tied inverters is an important electrical security issue addressed by the main Standards. This concern is justified in face of the fact that unintentional islanding can lead to abrupt variations of voltage and frequency, electrical damages, professional accidents, power quality degradation, and out-of-phase reclosure. In response to the islanding concern, the literature has proposed several Anti-Islanding Protection (AIP) schemes that can be divided in passive and active methods. Many of the active AIP is based on the insertion of some disturbance in the inverter current in order to deviate the frequency out of the allowed thresholds, tripping the inverter internal disconnection system. Thus, the main objective of this paper is to analyze the performance of the Active Phase Jump with Positive Feedback (APJPF) algorithm compared to other well-known frequency drift-based solutions. More than that, this work covers the Non-Detecti... [more]

According to Thomson Reuters DataStream database, 22,458 merger and acquisition (M&A) transactions with a deal value exceeding 7016 billion Euros have occurred in the energy worldwide sector during 1995−2020. International M&A enable promotion of sustainable competitive advantages, accelerates industry developments and helps to promote sustainable social and economic development. Our research aims to systemize empirical studies, which would enable assessment of the relationship between M&A transactions and the principles of sustainable development in the energy sector. To do so, SALSA (search, appraisal, synthesis and analysis) methodology with additional snowballing technique (chain-referral sampling) is conducted. The current research contributes to existing knowledge by providing an extensive systematic literature review of the academic publications on sustainable development and M&A deals. This paper may be insightful for practitioners and scholars because it highlights the most re... [more]

Kazakhstan has a relatively high level of overall gender development, as well as of female employment in its energy industries. Diverse views and backgrounds are necessary to address the challenges of curbing emissions in Kazakhstan, a major fossil fuel producer and exporter. However, our analysis of the Labor Force Survey indicates that female representation among energy sector managers and overall workforce has been falling over time. Moreover, we find that women in Kazakhstan’s coal mining, petroleum extraction, and power industries are concentrated in low-skilled and non-core occupations. Next, by analyzing data on labor compensation within energy occupations, we discover signs of persistent vertical discrimination, which may reduce incentives for women to upgrade their skills. Finally, we find that major shocks, such as the COVID-19 pandemic, may stall or reverse prior progress in increasing the energy sector’s gender diversity. Our findings contribute to raising gender awareness... [more]

In recent years, the increased distributed generation (DG) capacity in electric distribution systems has been observed. Therefore, it is necessary to research existing structures of distribution networks as well as to develop new (future) system structures. There are many works on the reliability of distribution systems with installed DG sources. This paper deals with a reliability analysis for both present and future medium voltage (MV) electric distribution system structures. The impact of DG technology used and energy source location on the power supply reliability has been analyzed. The reliability models of electrical power devices, conventional and renewable energy sources as well as information and communications technology (ICT) components have been proposed. Main contribution of this paper are the results of performed calculations, which have been analyzed for specific system structures (two typical present network structures and two future network structures), using detailed... [more]

As the number of threats and the severity of their impact increases, an ever greater emphasis is being placed on the protection of critical infrastructure. Thus, the issue of resilience, or its assessment and strengthening, is increasingly coming to the fore. The resilience assessment of critical infrastructure, especially in the energy sector, has received considerable attention due to the high level of interest in this issue. However, the issue of strengthening resilience poses a significant challenge not only in the energy sector but also in the entire critical infrastructure system. Despite the great importance of this area, there is not a large number of authors moving in this direction and paying attention to resilience-strengthening tools. For this reason, the aim of this article is to provide the reader with a comprehensive methodological overview of resilience strengthening in the critical energy infrastructure sector. This article also provides an overview of internal and ext... [more]

This paper adopts the Modular Multilevel Converter Type Railway Power Conditioner (MMC-RPC) equipment to effectively manage the power quality of the high-speed railway traction power supply system including the reactive power and negative sequence component. Firstly, the single-phase model of the MMC was established to deduce the working characteristics of the MMC-RPC and its compensation principle for the traction power supply system with the v/v wiring transformer. Secondly, the adaptive VSG control strategy was adopted for the inverter of the MMC-RPC to provide dynamic inertial and damping support for the traction power supply system based on the virtual synchronous generator (VSG) control. Compared with the traditional double closed-loop (DCL) and VSG controls, it has better anti-disturbance and dynamic performance. The root locus analysis of control parameters based on a small signal model shows that VSG control can provide more stability margin. Furthermore, Differential Flatness... [more]

The evolution of changes in shopping in the modern society necessitates suppliers to seek new solutions consisting of increasing the efficiency of transport processes. When it comes to controlling the flow of goods in modern distribution networks, planning and timely deliveries are of particular importance. The first factor creating a competitive advantage involves the tendency to shorten order delivery times, especially for products with a short shelf life. Shorter delivery times, in turn, extend the period of effective residence of the product “available on the shelf”, increasing the likelihood of its sale. The second component in line with the Sustainable Development Strategy consists of aspects related to the protection of the natural environment, in particular those related to car transport. In this case, the fuel consumption and the level of emitted toxic substances (including carbon dioxide) are analyzed and assessed. Bearing in mind the above, this article presents the problem... [more]

The reasonable and efficient use of the abundant biomass resources in rural areas has not been realized. Therefore, the concept of a combined cooling, heating, and power (CCHP) microgrid system, considering biomass pyrolysis and gasification, has been developed by researchers. A biomass gasification device can fully use biomass resources and can play a role in absorbing wind energy. Meanwhile, in order to minimize the operating cost of each micropower supply unit, as well as the environmental pollution costs, researchers have also established an optimal scheduling model for CCHP microgrids, which uses the sparrow search algorithm. In this paper, we have improved upon the traditional sparrow algorithm to solve the problems of its uneven population distribution, poor global search ability, and the risk of falling into local optima, through the development of the random walk sparrow search algorithm (RSSA). First, a sinusoidal chaotic map is used to generate the early-generation sparrow p... [more]

In order to find the causes of statistical line loss abnormalities and propose better loss reduction strategies, it is necessary to improve the accuracy of theoretical line loss calculations. Since Distributed Generation (DG) access to the distribution network causes variability of power flow in the distribution network within a short period, the error of the traditional line loss calculation method increases. For the line loss calculation of medium-voltage distribution networks containing DGs with high-density collection data, a continuous line loss calculation method for the distribution network was proposed, aiming at improving the accuracy compared with the traditional line loss calculation method. The proposed method makes full use of the high-density collection data on the dispatch side and DG side, distributing the supply power to each load node by power to calculate real-time power flow, thus obtaining a more credible line loss value. The effectiveness and accuracy of the propo... [more]