The paper presents an analytical discussion of how to improve the energy efficiency of the steam cushion system operation for a Thermal Energy Storage (TES) tank. The EU’s green deal 2050 target policy requires an increase in the energy efficiency of energy production and use, as well as an increase in the share of renewable energy in the overall energy production balance. The use of energy-efficient TES is considered as one of the most important technologies to achieve the objectives of this EU policy. The analyses presented in the paper of energy-efficient operation of steam cushion (SC) systems were carried out by using operational data received from three District Heating Systems (DHSs) that supply heat and electricity to one of the largest cities in Poland and are equipped with the TES systems. These three analyzed TESs differ in capacities from 12,800 to 30,400 m3, tank diameters from 21 to 30 m and shell height from 37 to 48.2 m. The main purpose of using a steam cushion system... [more]

Detection of the axial displacement of power-transformer winding is important to ensure its highly reliable operation. Frequency response analysis is a promising candidate in detecting the axial displacement. However, a method of detecting the axial displacement at an incipient stage without the need for fingerprint data has not been investigated yet. This paper focuses on resonances showing a bipolar signature in the transfer function of inductive interwinding measurement, which is sensitive to the axial displacement of the winding. Transfer functions in the inductive interwinding measurements of eight power transformers are measured before shipping to elucidate the features of resonances showing a bipolar signature. The measured resonances showing the bipolar signature can be divided into the “stair type” and the “crossing-curve type”. It is found that the grounding points in an inductive interwinding measurement determine the type of resonance showing the bipolar signature, irrespec... [more]

Solar energy is planned to undergo large-scale deployment along with Thailand’s transformation to a carbon neutral society in 2050. In the course of energy transformation planning, the issue of energy infrastructure adaptation to climate change has often been left out. This study aims to identify climate-related risks and countermeasures taken in solar power plants in Thailand using thematic analysis with self-administered observations and structured interviews in order to propose points of consideration during long-term energy planning to ensure climate adaptation capacity. The analysis pointed out that floods and storms were perceived as major climate events affecting solar power plants in Thailand, followed by lightning and fires. Several countermeasures were taken, including hard countermeasures that require extensive investment. Following policy recommendations were derived from the climate-proofing investment scenario study. Policy support in terms of enabling regulations or fina... [more]

The recovery of oil and gas from underground reservoirs has a pervasive impact on petroleum-producing companies’ financial strength. A significant cause of the low recovery is the plugging of reservoir rocks’ interconnected pores and associated permeability impairment, known as formation damage. Formation damage can effectively reduce productivity in oil- and gas-bearing formations—especially in sandstone reservoirs endowed with clay. Therefore, knowledge of reservoir rock properties—especially the occurrence of clay—is crucial to predicting fluid flow in porous media, minimizing formation damage, and optimizing productivity. This paper aims to provide an overview of recent laboratory and field studies to serve as a reference for future extensive examination of formation damage mitigation/formation damage control technology measures in sandstone reservoirs containing clay. Knowledge gaps and research opportunities have been identified based on the review of the recent works. In additio... [more]

The manufacturing industry consumes electricity and natural gas to provide the power and heat required for manufacturing. Additionally, large amounts of electric energy and heat energy are used, and the electricity cost, amount of environmental pollution, and equipment maintenance cost are high. Thus, optimizing the management of equipment with new energy is important to satisfy the load demand from the system. This paper formulates the scheduling problem of these multiple energy systems as a multi-objective linear regression model (MLRM), and an energy management system is designed focusing on the economy and on greenhouse gas emissions. Furthermore, a variety of optimization objectives and constraints are proposed to make the energy management scheme more practical. Then, grey theory is combined with the common MLRM to accurately represent the uncertainty in the system and to make the model better reflect the actual situation. This paper takes load fluctuation, total grid operation c... [more]

This paper describes an interior permanent magnet synchronous motor (IPMSM) based on a new adjustable field method. The proposed PM motor achieved magnetic field control utilizing magnetic saturation. In this paper, a back electromotive force (e.m.f.) measurement test and a load test using the prototype motor were conducted to clarify if the proposed motor had a wide operation range. In the back e.m.f. measurement test, it was confirmed that the proposed motor had a wide magnetic field controllable range of 51.7%. In addition, it was revealed, through the load test, that the proposed motor had a wide operating range, including both low-speed high-torque and high-speed low-torque driving conditions. Moreover, based on electromagnetic field analysis, the magnetic field control performance of the proposed adjustable field method was compared with the conventional field weakening control and other adjustable field methods. As a comparison result, it was verified that the proposed motor had... [more]

One of the recent problems on waste sorting systems is their performance evaluation for proper decision making and management. For this purpose, multi-criteria methods can be used to evaluate the sorting system from both operational and financial perspectives. According to a recent literature review, there are no solutions for evaluating waste sorting systems that take into account: sorting point utilisation, sorting efficiency, waste stream irregularity, and technical system availability. In addition, the problem of data uncertainty and the need to use expert judgements indicate the need for the implementation of methods adjusted to the qualitative and quantitative assessment, such as the fuzzy approach. Following this, in order to overcome the presented limitations, the authors introduced the new assessment method for waste sorting systems based on multi-criteria model implementation and fuzzy theory use. Therefore, the developed model was based on a hierarchical fuzzy logic model fo... [more]

This paper presents safety-related modifications to the improved high-voltage unity-gain buffer and their impact on the operation quality of this circuit. The analyzed buffer architecture combines the virtues of source and gate followers. It provides high input impedance to the gate follower and voltage gain precision to the source follower while retaining a very simple structure and an extremely short signal path. These properties enable its various applications, e.g., as an interconnection of voltage and current mode function blocks in signal paths of medium- and high-voltage integrated circuits. The scrutinized buffer consists of MOS devices with different maximum interterminal voltages, which results in the necessity of enhancing its architecture with a set of safety devices to ensure non-destructive power-up, normal operation, and power-down phases of the buffer operation. The consequences of the implemented safety changes vs. the influence of the physical implementation process o... [more]

The issues discussed in this article concern the energy efficiency of transport tasks carried out by the air SAR system in the Baltic Sea. Search and rescue (SAR) are rescue operations consisting of finding people in danger, providing them with help, and delivering them to a safe place. The transport task is an element of the rescue operations carried out in the open water area. It is carried out by a given type of helicopter from a strictly defined rescue base. The aim of the article is to develop a method of selecting the base and means of transport for the transport task carried out by the air SAR system, based on the assessment of energy efficiency of a given transport task. The article proposes a selection model; parameterization of the model was carried out, indicators of energy efficiency evaluation were determined, and limitations were indicated. In practical terms, the authors’ model of selection is presented on the example of transport tasks carried out by the air SAR system... [more]

In this study, the mixing power and the axial and radial velocity distributions were determined for the standard PBT45-6 impeller with inclined blades and for three NACA impellers with airfoil blades. On the basis of the velocity distributions obtained by means of PIV techniques, the pumping efficiency and the size of the secondary circulation for the tested impellers were determined. The next stage was to calculate the efficiency of the impeller operation, in which the comparative criteria were the values of the mixing energy in the form of a dimensional and dimensionless criterion. The lowest mixing energy was obtained for impellers with symmetrical profiled NACA0021 blades, which was 20% lower than the similar mixing energy obtained for the standard PBT45-6 impeller.

Protection of the natural environment is a key activity driving development in the transport discipline today. The use of simulators to train civil aviation pilots provides an excellent opportunity to maintain the balance between efficiency and limit the negative impact of transport on the environment. Therefore, we decided to determine the impact of selected simulations of air operations on energy consumption. The aim of the research was to determine the energy consumption of the flight simulator depending on the type of flight operation and configuration used. We also decided to compare the obtained result with the energy consumption of an aircraft of a similar class, performing a similar aviation operation and other means of transport. In order to obtain the results, a research plan was proposed consisting of 12 scenarios differing in the simulated aircraft model, weather conditions and the use of the simulator motion platform. In each of the scenarios, energy consumption was measur... [more]

One of the requirements for the safe operation of customer premises equipment (CPE) is an adequate grounding system as a means to divert high fault currents to the ground. In this work we report on the results of an experimental study of the impulse characteristics at a charging voltage of 30 kV on the surge protective device connected to 16 earth electrodes and installed at two sites, giving various ground resistance at low voltages, RDC values. All of these grounding electrodes were installed and tested under the same charging voltage to determine the effectiveness of ground electrodes toward the damage of a modem at the premises. We observed that modems did not experience damage when the ground electrode of the distribution pole (DP) had an RDC below 30 Ω in general and below 46 Ω when ground electrodes installed in low resistivity soil were used. The impulse polarity did not affect the damage susceptibility of the CPE.

In this article, we focus on the development and scope of virtual power plants (VPPs) as a strategy to facilitate the integration of distributed energy resources (DERs) in the power system. Firstly, the concepts about VPPs and their scope and limitations are introduced. Secondly, smart management systems for the integration of DERs are considered and a scheme of DER management through a bottom-up strategy is proposed. Then, we analyze the coordination of VPPs with the system operators and their commercial integration in the electricity markets. Finally, the challenges that must be overcome to achieve the large-scale implementation of VPPs in the power system are identified and discussed.

As the continuous consumption of non-renewable energy leads to resource shortages, distributed PV generation technology has received widespread attention. The DC microgrid is an effective way to connect distributed PV generation. However, DC microgrids have numerous challenges, such as the absence of zero current crossing point and high fault current rising rate. In the paper, a bi-directional DC solid-state circuit breaker based on flipped Γ-source is proposed to overcome some of the challenges in DC microgrid. The topology uses the mutual inductance current generated by the transformer to force the SCR naturally commutates off. Which can rapidly interrupt and isolate the faulty part, and at the same time, there will be no circulating current impact on the source side. The diode bridges allow the response to faults on either the source or load side with only a single controlled switch. Therefore, the topology is simplified while enabling it to obtain the capability of bidirectional op... [more]

High geotemperatures are encountered during tunnel construction in areas with complex geological structures, which can seriously affect personnel and equipment in the process of tunnel construction and operation. The Nige tunnel, a deep-buried extra-long tunnel, was selected to monitor the geotemperature during construction. The air, rock, and water temperatures during the tunnel construction were measured at the tunnel face, and the actual temperatures of the rock or water body at the tunnel face were measured by advanced drilling. The variation trends of the water temperature, air temperature, and flow of water with the tunnel mileage were analyzed. The differences in three measured rock temperatures in three advanced drillings were revealed. The results showed that the Nige tunnel had a maximum water temperature of 63.4 °C, maximum rock temperature (Rock T) of 88.8 °C, and maximum air temperature (Air T) of 56.4 °C. Increasing trends of the air, rock, and water temperatures with the... [more]

Academics and practitioners are paying increasing attention to green marketing as lesser damage to the environment and future generations become a priority in a current complex business environment. Despite the expanding studies in this field, there is still a lack of psychometrically sound scales to measure green marketing practices. To fill this gap, the research aimed to develop and evaluate a multifaceted green marketing scale. First, we draw on theoretical evidence to define and conceptualize the construct of green marketing. Then, we use a multistudy scale development process to create and validate the Green Marketing Scale (GMaS). Two groups of participants were used for the validation of the scale. Study 1 (n = 102), with the help of exploratory factor analysis (EFA), refined and reduced the items, proposed the factor structure. Study 2 (n = 155) established the validity of the construct and the reliability of the scale. The authors have tested the six-factor model against the... [more]

Motors powered directly from solar panels are becoming more and more popular in pump applications. However, solar panels can be the source of operational issues due to varying irradiance, ambient temperature, weather. This paper shows how it is worth expanding a solar induction motor drive to provide an uninterrupted flow of electricity to the motor. In addition, the main components of the uninterruptible induction motor drive are presented, including the LLC (inductor-inductor-capacitor) converter, the three-phase inverter, and the three-phase rectifier. LLC converters that can increase the voltage from 25−40 V to 330 V cannot be bought directly from manufacturers. Therefore, a custom LLC converter was made for the research. It was necessary to build a custom converter to avoid the use of solar panel strings. This way, solar panels connected in parallel can be used. A low-voltage (25−40 V) supply was implemented from the solar side, while the induction motor requires 230 V AC three-ph... [more]

A regional integrated energy system (RIES) is an electricity-centric multi-energy system that can realize the mutual conversion of electricity, heat, cold, and other energy. Through multi-flexible resource interaction and the transaction of multi-investment entities, the efficiency of energy utilization can be improved. To systematize energy-consuming entities and scale photovoltaic-based renewable energy in a distribution network, the energy-consuming behavior, energy-producing schedule, and trading strategy can be coupled. Considering the interaction between the energy-consuming behavior and the uncertainty of distributed photovoltaic output, an optimal operation method for RIES is proposed on the basis of social network theory and an uncertain evolutionary game method in this paper. From the perspective of the operator, the overall profits of RIES are maximized considering the entity characteristics of both the demand and the supply side. A case study shows that the proposed method... [more]

The aim of this study is to investigate the effects of the separator thickness on not only the heat and mass transfer characteristics, but also the power generation characteristics of a polymer electrolyte membrane fuel cell (PEMFC) with a thin polymer electrolyte membrane (PEM) and thin gas diffusion layer (GDL) operated at higher temperatures of 363 and 373 K. The in-plane temperature distributions on the back of the separator at the anode and cathode, which are the opposite sides to the GDL, are measured using a thermograph at various initial cell temperatures (Tinit), relative humidity (RH) levels, and supply gas flow rates. The total voltage corresponding to the load current is measured in order to evaluate the performance of the PEMFC. As a result, it is revealed that the effect of the RH on the power generation characteristics is more significant when the separator thickness decreases. It is revealed that the power generation performance obtained at high current densities decrea... [more]

This work presents the development, validation, and sensitivity analyses of a portable device capable of performing high-frequency dielectric spectroscopy tests on site. After a brief introduction on the operation principle and the description of the impact of frequency on dielectric spectroscopy, the article presents the results of tests on reference samples confirming good agreement with expected values. The frequency region in which the device operates, 1−200 kHz, was chosen because of its correlation with oxidative species of polymeric compound. The sensitivity analyses were performed measuring the dielectric response of low voltage cables with different aged lengths. The outcome of these tests is twofold. On the one hand, they confirm the suitability of the technique for aging evaluation, and, on the other hand, they allow the assessment of the minimum aged length (damage ratio) which causes appreciable variations on the obtained dielectric spectrum. This quantity was found to be... [more]

In the context of an eco-responsible production and distribution of electrical energy at the local scale of an urban territory, we consider a smart grid as a system interconnecting different prosumers, which all retain their decision-making autonomy and defend their own interests in a comprehensive system where the rules, accepted by all, encourage virtuous behavior. In this paper, we present and analyze a model and a management method for smart grids that is shared between different kinds of independent actors, who respect their own interests, and that encourages each actor to behavior that allows, as much as possible, an energy independence of the smart grid from external energy suppliers. We consider here a game theory model, in which each actor of the smart grid is a player, and we investigate distributed machine-learning algorithms to allow decision-making, thus, leading the game to converge to stable situations, in particular to a Nash equilibrium. We propose a Linear Reward Inac... [more]

Power generation using concentrating solar energy is a potential solution to provide clean, green, and sustainable power generation in the long term. The objective of this paper is to analyze the performance of a parabolic trough collector-based concentrating solar power (CSP) plant by selecting four different reference days (i.e., 22 March, 22 June, 22 September, and 22 December), representing four seasons in Mongolian climate conditions. Numerical simulation of the 50 MW CSP plant was performed, both at nominal and part-load conditions using the heat balance method considering variations of power load owing to the direct normal irradiation (DNI). The results revealed that the 50 MW CSP plant could operate well throughout the year, and it showed the highest value of operating performance for the 22 June due to the higher DNI and small solar incidence angle. The operating performance for the 22 March and 22 September is nearly similar. The lowest value of operating performance occurred... [more]

The expansion of renewable energy with its volatile feed-in character places higher demands on the power grid of the future. Large-scale storage systems (LSS) are a promising option for supporting the electricity grid and have been gaining importance in the last years, both on the market for frequency containment reserve (FCR) and in research. The majority of publications investigating the interaction between storage and FCR are based on simulations rather than on field measurements. This paper presents the analyses of multi-year, high-resolution field measurements of the hybrid 6 MW/7.5 MWh battery storage “M5BAT” to address this issue. The influence of FCR operation on the operation and degradation of the hybrid LSS and the individual battery technologies is investigated via a statistical evaluation of the historical operating data between 2017 and 2021. The data-based analysis of the LSS and the individual battery technologies reveals a high availability of the LSS of over 96.5%. Fu... [more]

Different risks are associated with the operation and maintenance of wind farms in cold climate regions, mainly due to the harsh weather conditions that wind farms experience in that region such as the (i) increased stoppage rate of wind turbines due to harsh weather conditions, (ii) limited accessibility to wind farms due to snow cover on roads, and (iii) cold stress to workers at wind farms. In addition, there are risks that are caused by wind farms during their operation, which impact the surrounding environment and community such as the (iv) risk of ice throw from wind turbines, (v) environmental risks caused by the wind farms, and (vi) social opposition risk to installing wind farms in cold climate regions, such as the Arctic. The analysis of these six risks provides an overall view of the potential risks encountered by designers, operators, and decision makers at wind farms. This paper presents a methodology to quantify the aforementioned risks using fuzzy logic method. At first,... [more]

Power generation technologies are essential for modern economies. Modal Analysis (MA) is advanced but well-established method for monitoring of structural integrity of critical assets, including power ones. Apart from classical MA, the Operational Modal Analysis approach is widely used in the study of dynamic properties of technical objects. The principal reasons are its advantages over the classical approach, such as the lack of necessity to apply the excitation force to the object and isolate it from other excitation sources. However, for industrial facilities, the operational excitation rarely takes the form of white noise. Especially in the case of rotating machines, the presence of rotational speed harmonics in the response signals causes problems with the correct identification of the modal model. The article presents a hybrid approach where combination of results of two Operational Modal Analyses and Experimental Modal Analysis is performed to improve the models’ quality. The pr... [more]