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The power transformer is one of the most important equipments that has a critical role in good electrical power delivery. Ageing of paper insulation inside the transformer is irreversible and hugely related to the operation of power transformer. This study involved inspection data from in-service and out-of-service 150 kV power transformers provided by the Indonesian electric company. The degree of polymerization (DP) of the cellulose paper insulation and furanic compound in the insulating oil can be used to estimate the transformer's lifetime. In this study, the correlation between HI decreasing rate (HI dec_rate ) and the loading factor of 115 transformers historical data was observed. The DP of the transformer paper was predicted (DP pred ) using the ANFIS model using the dielectric characteristics and dissolved gases as input. The results show that the correlation between the DP pred decreasing rate (DP dec_rate ) and the loading factor is more significant than that between the HI dec_rate and the loading factor

In this contribution a possibility of electrochemical production of chlorine for water disinfection, by using photovoltaic panels from solar energy, is described. A simple way of chloride production by means of a photovoltaic panel, comparable with classical electrical power source was performed on an experimental device. By using photovoltaic panel with nominal output 50 W and solar irrigation 380 – 550 W/m2 chlorine production was 0.3 mg/min, which represents amount of chlorine sufficient for disinfections of approximately 4000 l water per day.

Solar energy, wind energy etc. are the main sustainable energy sources used around the world. These sustainable energy sources are used in day-to-day life in various forms for numerous purposes. One of the highly used sustainable energy sources is the solar energy which with the help of photovoltaic (PV) cells can be made use for the generation of electrical power. However, these sources generate less voltage values and thus it requires a high gain converter. In this paper, a modified Luo with flyback DC to DC converter is presented that assures high voltage gain, single switch, less stress across the components and less ripple current. Furthermore, the simulations along with the hardware prototype for the presented converter is carried out and presented in this paper.

Solar photovoltaic power plants are in rapid expansion throughout the world, with the total area occupied by panels being linked to the total electrical power produced. This paper considers this case as an instance of the generic problem of estimating the total area occupied by a class of interest in spaceborne hyperspectral images. As the spatial resolution characterizing these sensors is too coarse, spectral unmixing techniques identify the contribution of a specific material to the spectrum related to a single image element. Final results are obtained by summing all contributions in an area of interest, and favourably compared to pixel-based detection, also using higher resolution Sentinel-2 data. The data used in this paper are acquired by the currently operative DESIS sensor, mounted on the International Space Station, encouraging the use of spaceborne imaging spectrometers for such applications.

Grid codes play a significant role in setting power system characteristics, such as ramp rate of different kinds of power plants. Using novel energy sources, like solar energy, for supplying electrical power demands, develops the requisite for controlling the characteristics of these sources such as their power ramp rates. While solar power is going to increase or decrease, ramp rate control is crucial. There have been suggested different strategies for power ramp rate control. Some of these strategies need batteries and some do not. Due to solar radiation uncertainties, it is necessary to use energy storage systems to control power ramp rate. On the other hand, batteries add huge costs and unreliability to the power systems. As a result, there is a trading-off among initial cost, reliability, security, and operation costs for selecting an optimal strategy. Also significance of the grid is a decisive factor. In this paper, some power ramp rate control schemes are discussed, and the advantages and disadvantages of different types of schemes have been analyzed. Also, in this literature different kinds of power ramp rate control strategies for photovoltaics have been clustered into some major sets. Besides, power ramp rate control is essential for novel schemes such as virtual synchronous machines, so emerging virtual inertia in novel power grids is another motivation to establish different methods for controlling the power ramp rate of renewable energy sources. Thus, in this paper, there is a section discussing the applications of power ramp rate control schemes.

The contribution of solar photovoltaic (PV) in the electrical power sector is increasing expeditiously. Recent interest in the integration of solar PV into the grid raises concerns about the synchronization technique. Continuous research has successfully replaced the small stand-alone system with a grid-tied PV system. A grid-tied PV system is popular due to the abundance of solar light and advanced power electronics techniques. This paper helps to provide a basic conceptual framework to develop a superior grid-tied system. Synchronization is a crucial problem in grid-tied inverters operation and control research indicates that frequency, phase, and amplitude of voltage are the most crucial parameters that need to be measured and controlled for grid-tied application. This paper presents the state of the art of various synchronization methods for both single-phase and three-phase units. A phase-locked loop (PLL) is a popular grid synchronization approach, which needs to sustain power system oscillations as its vulnerability influences the produced reference signal. Traditional PLL catches the frequency and phase through feedback loop-filter (LF) to improve steady-state capability during adverse grid conditions. The review paper focuses on the power stages architecture of PV fed grid synchronization along with a comparison of various PLL techniques based on their merits and demerits. This paper will be the one-stop reference for the researchers in the area of PV-fed grid.

Energy harvesting in the railway industry has great potential for many applications. Energy harvesters can provide electrical power for track-side, on-board, and infrastructure instruments, including health monitoring sensors, signaling, switches, and safety equipment. Due to the rapidly growing trend of the railway network, a considerable number of instrumentations need to be located in inaccessible, remote, and harsh locations where providing the energy through cable is almost impossible. In these cases, self-powered sensors and distributed power generators can be used based on energy harvesting techniques. High-intensity sound and vibration levels in the railway environment prove them to be promising sources of energy for self-powered devices. This paper aims to provide a comprehensive review on the railway sound and vibration energy harvesting, from the beginning to the most state-of-the-art. This paper addresses different energy harvesting resources for the railway environment, diverse methods of energy harvesting and their advantages and drawbacks, and at the end, energy harvesting applications in the railway industry. Different models and prototypes of energy harvesters are introduced and compared. Finally, the potential applications of railway energy harvesting are addressed, and future challenges and trends are discussed. The scheme of the present paper is designed in a way to provide readers the most significant principles that need to be considered in the design of railway energy harvesters.

This research paper attempts to investigate both the long-run and causality relationship among electric power consumption (EPC), technological transfer, financial development (FD), and environmental quality for the Saudi Arabia (KSA) economy from 1980 to 2019. In doing so, we propose a carbon emission function tested by incorporating multi-steps techniques such as autoregressive distributed lag (ARDL) has been exploited to determine the existence of cointegration or no; while vector error correction model (VECM) has been applied to decide the direction of causality. In this paper we have proposed two proxies of technological transfer, namely imported technology (MT) and Technical cooperation grants (TCG). The results indicate the existence of cointegration between the concerned series. Besides, the existence of a feed-back effect among variables (except TCG) in the long-run. However, in the short run feed-back effect exists among EPC and EnvQ; MT and EnvQ; EPC and MT. Thus, the paper provides original visions for policy makers to encourage the technological transfer by financing and supporting the electric energy sector which constitutes the main locomotive to improve the environment quality for the KSA.JEL classification : C32, C52, O11, Q43

Life Cycle Climate Performance (LCCP) is a widely accepted metric to evaluate the carbon footprint of air conditioning (AC) systems “from cradle to grave.” This paper: (1) reviews the invention and evolution of LCCP, including a comprehensive timeline and bibliography; (2) documents the successful application of LCCP in the replacement of HFC-410A with HFC-32 in room air conditioners; (3) compares the conceptual frameworks and the operational approaches; and 4) reflects on the drawbacks of current LCCP research and points out possible future work. The major policy-relevant findings are: 1. The indirect emissions caused by energy consumption is 70 to 80 percent of the LCCP of AC systems in most countries but will decline in importance as electric power supply shifts rapidly from fossil fuel to renewable energy sources, which have near-zero carbon intensity; 2. The embodied greenhouse gas (GHG) emissions in refrigerant manufacture are, in most cases, negligible but the physical and chemical properties are crucial for system optimization for low carbon footprint; 3. The LCCP metric can be used for multiple purposes such as refrigerant selection and AC system architecture optimization; and 4. Data limitations in material manufacturing and the carbon intensity of electric power are the most significant challenges. Finally, this paper describes a variety of methods to fill in data gaps, including the correction factor method, the data-driven method, and the database searching method. The next-generation LCCP will be an enhanced evaluation process considering local climate, heat islands, and local power supply characteristics.

This paper provides an overview of hyperloop technologies, including a brief discussion of key components of a hyperloop system that determine the electric power requirements as a function of time. At-scale hyperloop systems do not yet exist, so a model was used to generate a set of load profiles for conceptual hyperloop realizations at four locations in the United States: two systems in California and one each in Colorado and Ohio. In all four cases, the modeled hyperloop load profiles included pulses in both active and reactive power. Grid modeling was performed to estimate the grid impacts and for discussing grid integration challenges. The paper discusses how energy storage systems might be used to eliminate the pulsating load characteristics or significantly reduce it to accommodate current grid planning guidelines.

This paper reviews and compares the main doubly-fed induction generator (DFIG) models for stability assessment in the literature by PSCAD/EMTDC simulation. The main contribution of the paper is a detailed study on small- signal admittance-based modeling of DFIGs for stability analysis. A complete DFIG model characterized from a 2x2 admittance-based transfer matrix is proposed which has frequency coupling between positive and negative sequences resulting from considering the PLL and the DC capacitor. In addition, two simplified DFIG models in the literature are derived from the complete model and discussed. The models are applied to stability analysis using the generalized Nyquist criterion and the positive-mode-damping stability criterion. The predictions are validated for several mechanical speeds and short-circuit ratios by PSCAD/EMTDC time-domain simulation. The study shows the need to apply the complete model to accurately assess subsynchronous stability, as significant differences from simplified models may occur at low frequencies.

Compared to their predecessors, the next generations of aircrafts will be more electrified, require more electrical power and operate at higher voltage levels to meet strict weight and volume constraints. The combined effect of low-pressure environments, increased voltage levels and compact designs intensifies the risks of premature insulation degradation due to electrical discharge activity. This paper studies the resistance to surface discharges of PTFE (polytetrafluoroethylene) and ETFE (ethylene tetrafluoroethylene), two insulation materials widely used in today’s aircraft wiring systems due to their outstanding properties, such as a wide temperature operation range and a high dielectric strength. The study is carried out in a low-pressure chamber, which was pressurized within the pressure range of 10–100 kPa that includes most aircraft applications. There is a compelling need for experimental data to assess the resistance of insulation materials to surface discharges at a very early stage as a function of the environmental pressure. Data on resistance to surface discharges in low-pressure environments for aeronautical applications are lacking, while most standards for insulation systems are based on tests under standard pressure conditions. The results provided in this work can be useful to design wiring systems for future more electric aircrafts, as well as to design fault detection systems for an early detection and identification of faults related to surface discharges. Therefore, the data and analysis included in this paper could be of great interest to design and develop insulation systems for wiring systems and standard assessment methods, as well as to design fault detection strategies for the early detection and identification of surface discharges for future generations of more electric aircrafts. This research was partially funded by the Ministerio de Ciencia e Innovación de España, grant number PID2020‐114240RB‐I00 and by the Generalitat de Catalunya, grant number 2017 SGR 967.

To reduce peak demand for electricity, smooth load curve shape, improvepower system safety and efficiency, this paper, by using intelligent homeappliance user operation comfort model is set up to quantify the acceptance,this paper proposes a maximum minimum load management algorithm basedon optimization strategy to change electric power use time and power con-sumption mode.The results show that the proposed model and algorithm canforecast and manage the power load well, and can reduce the peak to averageratio by 14.3% and the total expenditure by 15.3% while maintaining theoperating comfort of power users to the maximum.The load managementproblem of multiple power users can reach Nash equilibrium in a finitenumber of iterations, and this Nash equilibrium point is also the globaloptimal point.

High rotor temperature of electrical machines can cause a series of insulation failures. In serious cases, it will lead to system operation failure. However, under the condition of high-speed rotation of rotor, the conventional temperature measurement by means of embedded temperature sensor is difficult to be utilized due to the limitation of power and data transmission. This paper proposes a parallel contactless transmission strategy of power and data based on magnetically-coupled resonance and capacitive radio frequency technology. Electric power is transferred contactlessly by means of magnetically-coupled resonance, while the parallel contactless transmission of data signals is realized by means of capacitive radio frequency technology. The experimental prototype was developed and installed on a 22kW induction motor. The results show that the clear data signal can be received on the stator side without filtering to realize parallel wireless transmission of electric energy and rotor temperature data. The research results of this paper can provide a good technical scheme for contactless rotor temperature measurement of large and medium-sized electrical machines.

The evaluation of electrical load estimation is requisitely of any electrical power system. This manner is needed for system obligation, economical distribution and maintenance time of electrical system. In this paper, we propose electrical load estimation method based on fuzzy inference system which gives accurate results for estimated loads in Iraq (Diyala governorateBaaquba city). And it can assist the electrical generation and distribution system that depends on important parameters (temperature, humidity and the speed of the wind). By considering the parameters temperature, humidity and the speed of the wind. These parameters are applied as inputs to the fuzzy logic control system to obtain the normalize estimated load as output by electing membership functions. It is exceptionally valuable to form a choice by taking into consideration these assessed readings that come to from the proposed FIS that displayed in this paper with precision of 0.969 from the real stack request.

As one of the core businesses of power grid enterprises, power marketing is not only a direct source of income for power grid enterprises, but also an important communication window between power grid enterprises and power users and power generation enterprises. The quality of electric power marketing will directly affect the company’s financial status and corporate image, which is the key work of leaders at all levels of power grid enterprises. As an important part of marketing business, electric power marketing audit plays a role in standardizing electricity consumption behavior of power users and maintaining normal electricity price order. This paper proposes to use big data algorithm to analyze customers’ illegal electricity use behavior. Taking the power supply company as an example, this paper uses big data algorithm to mine and analyze the data related to marketing business, so as to realize the judgment and early warning of users’ abnormal electricity use characteristics.

The paper presents a method for obtaining analytical dependences of the heat pump heat capacity and electrical power on the environment and the coolant parameters. A model based on polynomial approximation in two independent parameters is offered. The paper shows the model identification for the 7.5-12.5 kW air-to-water heat pumps from one manufacturer. The accuracy of the obtained model is estimated.

The global power industry is at the brink of a revolutionary change. For the survival of humanity, it is essential to tackle the grave issue of climate change. The power industry needs to shift to the utilization of clean energy to sustain the increasing energy demands without affecting the environment. Therefore, it is important to establish a power network which is sustainable, free fuel-based, ultra-low-cost, and reliable power network. This paper discusses solar and wind power as a sustainable energy source for such a power network. In addition to energy sources, the storage system to support the power infrastructure is discussed. The role of power electronics in reducing the cost of electrical power is also discussed. Finally, the paper is concluded along with a brief discussion.

Climate change problems cannot be addressed without a transformation of the energy production sector, since it is responsible for a significant share of total greenhouse gas emissions. For this reason, governments are promoting the use of Renewable Energy Sources (RES), especially wind and solar. In order to increase the penetration of RES, whose energy production cannot be controlled to follow the demand, more and more energy storage systems are needed, for ensuring adequacy and security to electrical power systems. This paper is focused on an innovative thermal energy storage technology based on fluidized solid particles, capable of receiving energy as electricity and storing it as heat for later use, e.g. produce steam for industrial applications. In such a system, electric energy is converted to heat by means of resistors, that can be supplied with AC and/or DC sources. In the paper, different use-case scenarios are presented, involving the grid and/or a photovoltaic plant as electric power sources. Then some possible configurations for power converters are described and compared, to find the most appropriate solution for each use-case scenario.

Among the various types of renewable energy sources (RES), the photovoltaic (PV) generators play a very significant role in the production of electrical power, as the technology of these generators has been well perceived for a long period. These generators have been trusted to be environment-friendly. In this paper, mainly photovoltaic (PV) system-generated power has been designed and installed for energy production. This paper aims to present a solar power predictive analysis using deep neural networks (DNNs). A variant of recurrent neural network (RNN), namely long short-term memory (LSTM), has been used to model a photovoltaic (PV) grid-connected array output and approximate the generated power. A new algorithm is proposed for assessing the PV power for different array setups. An extensive comparative study using the DNN techniques is performed for evaluating different types of grid-connected array setups. This study is beneficial for the reader and useful for engineers and researchers interested in DNNs applied to solar photovoltaic systems data generation.

Producción Científica, The widespread use of devices based on power electronics and other nonlinear loads has led to an increase in harmonic distortion that affects the quality of power systems. Therefore, the correct measurement of harmonic and interharmonic content is necessary. The International Electrotechnical Commission (IEC) standards define the concepts of spectral and time grouping required for such measurements. This paper demonstrates that the procedures defined in the IEC standards are not sufficiently accurate when several close interharmonic tones interact due to the lack of stability of the values that the Discrete Fourier Transform obtains in each sampling window, and to the inaccuracy in the measurement of interharmonic groups and rates when using the Hanning window. This paper proposes novel solutions based on time aggregation and the use of other groupings and alternative windows. The results obtained are compared with the results produced by applying the rectangular window indicated in the standards, using sensitivity analysis varying one of the tones and using experimental results measuring the output signals of frequency inverters driving induction motors. The proposed method achieves greater accuracy and stability in the measurement of spectral groupings and their related distortion rates in signals with abundant and dispersed interharmonic content.

This paper describes the matching of various loads to sources (including nonlinear ones). The purpose of matching is to extract the maximum available power from the source. This has particular importance for renewable sources and energy-harvesting devices, in which unused energy is just wasted. The main innovations in this paper include (and followed by examples) simplified calculation of the matching parameter for a controllable load and matching by means of a family of power-conservative two-port networks, denoted POPI (Pin = Pout), such as transformers, gyrators, loss-free resistors (LFRs) and series LFRs (SLFRs). An additional innovation described in this paper is a new, simplified model of an HF power amplifier based on the series LFR concept. This model predicts that the efficiency of the HF power amplifier operated under the matched-mode condition can significantly exceed the 50% efficiency limit that is predicted by the conventional model. As HF power amplifiers drive antennas in transmission and some wireless power transfer (which uses radiative techniques) systems, it is clear that the operation of such systems in the matched-mode condition is not restricted to a 50% efficiency limit.

The propensity to utilization of inexpensive, clean and distributed energy resources in the today's power systems structure are expanding due to various economic, political and sociological reasons. However, the power generated by these resources is extremely unpredictable, which is called uncertainty and exceptionally fluctuated drastically that is known as variability, during the operation epoch. So, exposure to these two features is great significance and value. This problem is known as the power system flexibility in the literature of electrical power system studies. Promoting flexibility in the system is too expensive and can be evaluated in different time frames. This paper studies the power system flexibility with the presence of uncertainty and variability of demand and supply side resources in a planning timeframe. This paper proposed an improved method for demand response uncertainty modeling with Z-number. This method is a hybrid possibilistic and probabilistic process. Furthermore, this paper applied an approved method for renewable generation uncertainty modeling with Monte Carlo. The scrutinies show, the most cost-effective way to consider the flexibility is planning timeframe, so this study proposed a novel paradigm for Flexibility-Constrained Integrated resource planning in presence of high penetration uncertain and variable demand-side and supply-side resources namely as FCIRPU/V-DSRs. The simulations are implemented with the proposed FCIRPU/V-DSRs methodology on a test system. The results show that this innovative framework provides a significant improvement in the power system flexibility at an inferior cost than other investigated methods.

The static var compensator (SVC) is one of the devices that has been widely used for reactive compensation to improve the capacity and flexibility of power transfer in the electrical power system. However, the SVC changes the voltages and currents of the power network to which it is connected. Consequently, the measured impedance can be changed and affect protection relays operation based on this characteristic. Several papers have been published about the SVC effects on distance protection applied in transmission lines (TL). However, it is not widely known the impact of SVC on the transient behavior of generators, such as protection against loss of excitation (LOE) in synchronous machines connected to TL with SVC. In this sense, based on the modeling of a test electrical power system in the PSCAD/EMTDC simulation environment, the assessment of the effects of SVC on the behavior of the ANSI 40 protection function for the conditions of the total LOE and partial LOE since these events can cause the synchronous machine to operate in conditions above the rated ones. In addition, this paper presents a testbed that allows performing secondary tests in physical relays when simulated signals are applied to perform protection studies in the presence of SVC in power systems.

Carbon foot print is latest hot discussion and all the countries are started the initiation to minimize it. One of the main carbon emission industries is thermal electrical power generating company. For the social welfare the emission has to minimize to maximum extend. The electrical power generation company as well needs to minimize the generation cost for the better operation. Minimizing carbon foot print and minimal power generation cost are opposite to each other. When the optimization focused to minimize the generation cost it lead to increase the carbon foot print and vice versa. This paper addresses the constraint the optimization problem which needs the objective of reducing both emission and generation cost. Electrical power generating cost of thermal power plant is nonlinear and non-convex in nature. Likewise the emission produced by the thermal power plant is complex mathematical problem. Intelligent algorithms are best suitable to solve these types of practical problems. In this paper hybrid of firefly algorithm and differential evolution technique is adopted to find the constrained emission minimization and cost minimization. Firefly algorithm works based on brightness, attractiveness and movement and there is no mutation process. Differential evolution technique has better mutation process and hence this mutation operation of differential evolution technique is introduced with firefly algorithm for the hybrid operation and to get better result. The research work is aimed to reduce the carbon foot print as well the generation cost of the power system.

The paper considers the problem of modeling the dependence of the value of thermal energy production by an electric power company on the air temperature using neural network technology. As an example of an electric power company producing thermal energy, the Public Joint-Stock Company (PJSC) Yakutskenergo. As consumers of thermal energy, organizations, enterprises and the population of the city of Yakutsk, are located at latitude 62 and characterized by a cold northern climate. The numerical experiments carried out in this paper have shown that the general trend of the temperature dependence of thermal energy production, observed empirically, is well described by a neural network

This paper presents a low-frequency oscillation compensation in an electrical power system connecting large-scale electric vehicle loads (EVs). The particle swarm optimization (PSO) method has been adapted to adjust the control parameters of the generator under Power System Stabilizer (PSS) parameters. The EVs charging stations have been directly installed to the power grid for the battery charging process of the EVs according to the increasing number of EVs. The DC fast charging of the large scale EVs has been significantly affected by the low-frequency oscillation of the grids that have been considered in terms of power system stability margin. This paper has aimed to solve the methodology for turning the PSS parameters by adapting the PSO via MATLAB® and DIgSILENT®. The PSS could control the low-frequency oscillation in the proposed power grids. The simulation system has selected the 6-bus testing system, which has increased the EVs loads by 50, 100, 150, 200, and 300 percentages at bus No. B3. The simulation results have indicated that the rotor low-frequency oscillation could control instability region. Therefore, the proposed PSS controller turning could handle the power system swing and adjust the power system stability. In this condition, the proposed PSO method should have been explicitly used for low-frequency swing control of the generator's rotor into a balanced state under the large-scale EVs penetration level.

A conventional electrical grid mostly depends on the electrical power generated from fossil fuels. However, the pollutants from fossil fuels are the key factors for adverse climate change. Most of the developed countries of the world have already recognized the fact that the energy mix requires to be diversified by incorporating renewable energy. This is especially relevant for many of the member countries of the Organization of Islamic Cooperation (OIC), consisting of 57 countries, whose abundance of fossil fuel reserve indicates that much of their electric power is still generated from fossil fuels. In order to integrate renewable energy sources into the hybrid energy mix, an existing conventional grid needs to undergo drastic changes. Alongside this, the population boom in the OIC member countries has caused higher demand for a steady supply of electricity that the conventional grids have long been struggling to cope with. With a view to solving this multifaceted problem, incorporation of the smart power management schemes is indispensable using a smart electrical grid, where information and communications technology is integrated into its major building blocks. This allows advanced applications of a grid, such as the formation of micro-grids, demand-side management, energy storage, high-tech power electronic converters, etc. As the smart grids are being adopted by many developed countries, it is high time for the OIC member countries to pay due attention to this development, if they have not already done so. This paper explains, with special focus on the OIC member countries, the various smart power management technologies, their operations and applications, and the benefits and challenges. Then it goes on to carry out the Strength-Weakness-Opportunity-Threat with Analytical-Heuristic-Procedure (SWOT-AHP) analysis to evaluate its feasibility of incorporation and the underlying strategies appropriate for its implementation. Furthermore, a Hybrid Multi-Criteria-Decision-Making (MCDM) analysis is performed to evaluate the sequence of the emphasis that should be given on each of the technologies from those available for the smart power management initiative. Finally, the study reinforces the stance by drawing parallels from the UN Sustainable Development Goals (SDG) and highlights the importance of the smart grid in line with the global vision of SDG. This paper aims at assisting the decision-makers in implementing smart power management schemes in the OIC member countries, in particular, and other countries of the world, in general.

More electric aircrafts (MEAs) are paving the path to all electric aircrafts (AEAs), which make a much more intensive use of electrical power than conventional aircrafts. Due to the strict weight requirements, both MEA and AEA systems require to increase the distribution voltage in order to limit the required electrical current. Under this paradigm new issues arise, in part due to the voltage rise and in part because of the harsh environments found in aircrafts systems, especially those related to low pressure and high-electric frequency operation. Increased voltage levels, high-operating frequencies, low-pressure environments and reduced distances between wires pose insulation systems at risk, so partial discharges (PDs) and electrical breakdown are more likely to occur. This paper performs an experimental analysis of the effect of low-pressure environments and high-operating frequencies on the visual corona voltage, since corona discharges occurrence is directly related to arc tracking and insulation degradation in wiring systems. To this end, a rod-to-plane electrode configuration is tested in the 20–100 kPa and 50–1000 Hz ranges, these ranges cover most aircraft applications, so that the corona extinction voltage is experimentally determined by using a low-cost high-resolution CMOS imaging sensor which is sensitive to the visible and near ultraviolet (UV) spectra. The imaging sensor locates the discharge points and the intensity of the discharge, offering simplicity and low-cost measurements with high sensitivity. Moreover, to assess the performance of such sensor, the discharges are also acquired by analyzing the leakage current using an inexpensive resistor and a fast oscilloscope. The experimental data presented in this paper can be useful in designing insulation systems for MEA and AEA applications.

As a developing nation with its increasing energy demands, Fiji is in the process of introducing renewables to generate green power to minimize its reliance on fossil fuels and to minimize greenhouse emissions. The paper focuses on green power generation with the available renewables. The overview deals with their prospective users and therefore the challenges to those sources within the view of the local context. Photovoltaic standalone systems connect peoples of remote areas with the rest of the country to upgrade their living standard. Power generating authority along with the Ministry of Energy of Fiji are actively involved in evaluating and incorporating these potentials for power generation. Hydropower, bioenergy, solar energy and wind power are the prominent renewables on which Fiji's future power generation would be based. The share of renewable energies in the urban power generation in the calendar year 2019 was about 53% (561.96 million units). 55.9% of the Fijian population lives in rural areas and settlements. The photovoltaic standalone system through the solar home system (SHS) project and mini-hydroelectric-grids have been introduced to electrify these areas. Photovoltaic grid-connected systems are being introduced in the urban population to increase green energy proportion in the country's electricity power generation. Photovoltaic road lights are being planned to replace conventional road lights. The emission of carbon dioxide by the power sector has been gradually reducing since 1993. In 2015, 1925 million metric tonnes of carbon dioxide was emitted which was 21% less than that of 2005. The Government of Fiji is committed to utilize natural renewable energy resources available and generate 99% green electrical power by 2030. This paper sets a benchmark for other pacific island nations in realizing the success that renewables are achieving in the isolated populations of Fiji.

Power transformers are most imperative and critical element in electrical power system grid. To have a consistent electricity supply it is obligatory to give substantial attention for upkeep of the transformer. To capitalize on the lifespan and reliability of transformers, it is significant to be aware of the ageing and damage of any internal as well as external parts such as winding, core, tap changer, bushings etc. of power transformers. Condition monitoring is a significant protagonist in asset performance management approach and right diagnosis will provide the indication of probable faults that may occur and means to get rid of it. For accurate measurements of failure chances and to estimate residual life of power transformers, industry standards have defined certain methods in order to associate outcomes from several routines, type and special tests. This paper covers a comprehensive review on established tests as a part of chemical, electrical and miscellaneous incipient faults such as dissolved gas analysis, oil testing methods, sweep frequency response analysis, recovery voltage method, partial discharge, infrared thermograph test, turns ratio test, dielectric dissipation factor, transformer winding resistance, core to ground test, and insulation resistance calculation. It also contemplates the practices extensively helpful for measuring the health index, lifecycle enhancement, condition-based assessment and probability of failures. This paper summarizes a comprehensive assortment of methods extracted from industry and academic resources and distinguishes internal faults in an integrated structure with inclusion of health index formulation and interpretation for lifecycle prediction and possible suggestions to improve the asset condition. Index Terms- Power Transformer, Incipient Faults, Condition Based Assessment, Health Index, Failure Analysis.

In the Industry 4.0 paradigm, the control of electrical power production and consumption in small energy nodes remains an important objective. The new energy production nodes are usually installed in locations with reduced power requirements. They can produce energy to cover the needs of the consumer and the excess can be pushed in the national power grid system. This paper proposes a scheme to control the balance between produced energy, the locally consumed energy and the energy pushed into the national power grid system, using grid controlled inverters. The inverter connects the local energy source, with the local consumer and also ensures a bidirectional connection to the national power grid system. The inverter can be programmed to satisfy the local consumer power requirements, from the local source or from the national power grid system, and it can also deliver the local excess energy to the national power grid system. The controller is connected with the Internet and is able to send data to an IoT server. This paper presents a solution, along with its supporting technology, to create a network infrastructure based on thinger.io IoT technology. We present this solution for control, monitoring and optimization the electrical power production and consumption for small consumers using the IoT technology. This device can be used in small farm areas where we can monitor and control the balance between energy production and energy consumption from local sources or from the national power grid system. The device can also be used to monitor and control energy flow in remote small industrial plants or agricultural farms.

Transitioning the energy sector to zero or net-zero emission of greenhouse gasses (GHG) and substantially reducing other pollutants is a massive, costly, and long-term effort. The typical starting point and centerpiece of energy decarbonization is the electric power sector. The sector is a large direct GHG emitter. It already has many technological, non-carbon emitting alternatives that are rapidly declining in capital and operating costs and improving in performance, making electricity the least expensive and accessible energy carrier to decarbonize. This paper explores what the modeling community should do to inform this transition. The underpinning premise of this paper is that policymakers genuinely want to be informed from the modeling community about their range of options, their ability to achieve various objectives, and possible unintended outcomes. Since the goal of the modeling community is to help inform policymaking, it is important that they hear the needs of policymakers, be it economic, technological, or social goals.

An interconnection of electric power networks enables decarbonization of the electricity system by harnessing and sharing large amounts of renewable energy. The highest potential renewable energy areas are often far from load centers, integrated through long-distance transmission interconnections. The transmission interconnection mitigates the variability of renewable energy sources by importing and exporting electricity between neighbouring regions. This paper presents an overview of regional and global energy consumption trends by use of fuel. A large power grid interconnection, including renewable energy and its integration into the utility grid, and globally existing large power grid interconnections are also presented. The technologies used for power grid interconnections include HVAC, HVDC (including LCC, VSC comprising of MMC-VSC, HVDC light), VFT, and newly proposed FASAL are discussed with their potential projects. Future trends of grid interconnection, including clean energy initiatives and developments, UHV AC and DC transmission systems, and smart grid developments, are presented in detail. A review of regional and global initiatives in the context of a sustainable future by implementing electric energy interconnections is presented. It presents the associated challenges and benefits of globally interconnected power grids and intercontinental interconnectors. Finally, in this paper, research directions in clean and sustainable energy, smart grid, UHV transmission systems that facilitate the global future grid interconnection goal are addressed.

The Africa Continental Free Trade Area presents an opportunity for the creation of a single continental electricity market in Africa. This market has the potential to promote the efficient development of electricity infrastructure and symbiotic electricity trading between members of Africa's five regional electric power pools. A framework is proposed to harness the opportunities presented by the African Continental Free Trade Area through the coordination of technical and commercial endeavors of the regional power pools in Africa. This includes fostering sharing mechanisms of best practices that support the development of national and international institutions, harmonizing regulations and grid codes, and promoting electricity trading opportunities that will catalyze the development of inter-regional infrastructure projects. In this paper, the authors propose a bilateral contract market that aligns with and complements the existing regional power pools without encumbering them with unnecessary bureaucracy. The paper's policy recommendations are designed to promote proactive adoption and compliance with the recommended best practices, market rules and regulations by market participants, motivated by their self-interests.

As a typical big data representative, the information of global Cellular Signal Strength (CSS), defined as the signal power received by mobile phones, plays an important role in geographic flow analysis, because the density of such information can reflect the urbanization variables such as population, gross domestic product, built-up area, electric power consumption, and etc. Despite the importance, the real-time analysis of global CSS distribution remains a challenging problem due to the large data scale. In this paper, a Display-driven Computing (DisDC) technique is designed and applied to provide efficient large scale interactive CSS visualization, generating results by calculating the value of each pixel that directly for display that can dramatically improve system capacity in big data handling. Specifically, we present an efficient CSS measurement algorithm, which introduces spatial indexes and a corresponding query strategy; besides, an optimized parallel computing architecture is proposed to ensure the ability of real-time visualization. Experiments show that our approach obviously outperforms traditional methods and is capable of handling more than 40 million base stations in real-time. Moreover, an online demonstration is provided at https://github.com/MemoryMmy/CSSMap.

In this paper, an integrated drive converter of segmented-double-stator switched reluctance machine (SDS-SRM) with isolation and non-isolation charging capabilities for electric vehicle (EV) is presented. The proposed converter can not only reduce the number of the power switches, but also implement multiple operation modes. In non-isolation charging mode, the motor windings and existing power switches constitute a buck/boost converter to charge the battery. The appropriate rotor positions are obtained to achieve torque-free control, and the interleaved phase currents control method is introduced to reduce the charging current ripples. In isolation charging mode, the inner-stator is powered by the utility grid to drive the middle-rotor, and converts electrical energy into mechanical energy. While, the outer-stator is operated in generation mode to convert mechanical energy into electrical energy. The SDS-SRM is served as a rotating transformer to transfer the electric power to charge the battery with the galvanic isolation function. A low power proof-of-concept prototype platform is built and experiments are carried out to verify the effectiveness of the proposed integrated drive converter and the corresponding control schemes.

This paper presents a suite of analytics that are proposed to be embedded in next-generation smart sensors in electric power grids. The proposed analytics take the electrical signals as the input and unlock the full potential in signal processing and machine learning for real-time event detection and classification. Meanwhile, a robust synchrophasor estimation mechanism is housed within the proposed sensor technology that will be triggered following a detected event and guides on the adaptive selection of the best-fit (most accurate) synchrophasor estimation algorithms at all times. Embedding such analytics within the sensor and closer to where the waveforms are captured, the proposed distributed intelligence solution technology mitigates the potential risks to communication failures and latencies as well as malicious cyber threats. Our experiments demonstrate that the introduced scheme achieves improved quality of measurements with a promising event detection and classification accuracy, collectively resulting in enhanced online situational awareness in modern power grids.

This paper presents a comprehensive literature review with focus on the difficulties electric vehicles (EVs) face to charge the battery while on a trip, and proposes a solution without the need of an expensive change in infrastructure. The proposed method charges EVs while en route from another vehicle, which will be referred to as vehicle-to-vehicle recharging (VVR). The aim of this system is to bring an innovative way for EVs to charge their battery without getting off route on a highway. The electric vehicle can request such a service from a designated charger vehicle on demand and receive electric power wirelessly while en route. The vehicles that provide energy (charger vehicles) through wireless power transfer (WPT) only need to be semi-autonomous in order to engage/disengage during a trip. The state-of-the-art is divided into three subsections relevant to the proposed system and where most of the innovations to reduce the burden of charging EVs can be found: (1) infrastructure changes, (2) device level innovations, and (3) autonomous vehicles. The infrastructure changes highlight some of the proposed systems that aim to help EVs become a convenient solution to the public. Device level innovations covers some of the literature on technology that addresses EVs in terms of WPT. And finally, the autonomous vehicle subsection covers the importance of such technology in terms of safety and reliability, that could be implemented on the VVR system. Furthermore, modeling, analysis, and simulation is presented to validate the feasibility of the proposed system.

Integrated power systems (IPSs) are popular in the shipbuilding industry. DC shipboard microgrids (dc-SMGs) have many advantages compared with ac ones in terms of system efficiency, operation flexibility, component size, and fault protection performance. Being in the exploring stage, dc-SMGs have several potential configurations with different system architectures and voltage levels. In a dc-SMG, functional blocks integrated include power generation modules (PGMs), propulsion system, high power loads, and pulse loads specifically in naval ships. In modern ships, the PGMs include not only generators and fuel cells (FCs) but also energy storage systems (ESSs), which cooperate with generators to improve the overall efficiency and reliability. High power electric converters are vital interfaces between the functional blocks and the dc distribution system. Rectifiers for generators take the tasks of dc bus voltage regulation and power sharing. Inverters for propulsion motors are responsible for the motor drive in different operating conditions. Bidirectional dc/dc converters for ESSs are used to provide supply-demand balance and voltage fluctuation mitigation. This paper makes a comprehensive review of power architecture, functional blocks including electrical machines and energy storage, as well as power converters in dc shipboard power systems.

The recent seismic events that occurred in South Korea have increased the interest in the re-evaluation of the seismic capacity of nuclear power plant (NPP) equipment, which is often conservatively estimated. To date, various approaches—including the Bayesian method proposed by the United States (US) Electric Power Research Institute —have been developed to quantify the seismic capacity of NPP equipment. Among these, the Bayesian approach has advantages in accounting for both prior knowledge and new information to update the probabilistic distribution of seismic capacity. However, data availability and region-specific issues exist in applying this Bayesian approach to Korean NPP equipment. Therefore, this paper proposes to construct an earthquake experience database by combining available earthquake records at Korean NPP sites and the general location of equipment within NPPs. Also, for the better representation of the seismic demand of Korean earthquake datasets, which have distinct seismic characteristics from those of the US at a high-frequency range, a broadband frequency range optimization is suggested. The proposed data construction and seismic demand optimization method for seismic capacity re-evaluation are demonstrated and tested on a 480 V motor control center of a South Korea NPP.

Spacecraft operation in ultra-low Earth orbits (150–250 km) can provide advantages for carrying out traditional tasks. At the same time, the long-term maintenance of spacecraft in such orbits requires the delivery of a propellant supply from the Earth to compensate the aerodynamic drag. An increase in the lifetime can be achieved with air-breathing electric propulsion (ABEP) using outboard atmospheric gases as a propellant. To ensure ABEP operation, it is necessary to provide the required electric power supply and density of ionized gas. At the same time, lowering the orbit altitude or extension of solar arrays is accompanied by a rise in aerodynamic drag, the required thrust to compensate it and, therefore, the required power supply. In this paper the problem of integrated optimization of the trajectories and layout parameters of spacecraft by the criterion of the ABEP power consumption at the fixed spacecraft volume is considered. Variations in the density and composition of the atmosphere and the periods of shading of the spacecraft are taken into account. An analytical solution is obtained depending on generalized parameters that combine such characteristics as the specific power of solar arrays, total thruster efficiency and aerodynamic drag coefficient. The dependencies of the orbit characteristics enabling the long-term maintenance of spacecraft with ABEP on the generalized parameters are determined.

Probabilistic wind power forecasting is an important input in the decision-making process in future electric power grids with large penetrations of renewable generation. Traditional probabilistic wind power forecasting models are trained offline and are then used to make predictions online. However, this strategy cannot make full use of the most recent information during the prediction process. In addition, ensemble learning is recognized as an effective approach for further improving forecasting performance by combining multiple forecasting models. This paper studies an online ensemble approach for probabilistic wind power forecasting by taking full advantage of the most recent information and leveraging the strengths of multiple forecasting models. The online ensemble approach is first formulated as an online convex optimization model. On this basis, a quantile passive-aggressive regression model is proposed to solve the online convex optimization model. Case studies and comparisons with other online learning methods are conducted on an open wind power data set from Belgium. Results show that the proposed method outperforms competing methods in terms of pinball loss and Winkler score with high reliability.

Series-connected multi-pulse rectifiers (MPRs) are used to provide high quality electric power for high-voltage and high-power occasions. Due to conventional MPRs have limited harmonic reduction ability that cannot fulfill the related harmonic standard, some effective DC side harmonic reduction methods have been proposed to further improve power quality of the MPRs. This paper gives a comprehensive review on DC link harmonic reduction methods of series-connected MPRs. Passive and active harmonic reduction mechanisms are respectively analyzed based on two typical topologies, which are theoretical foundations for understanding and constructing novel harmonic reduction circuits (HRCs). Some useful DC side HRCs are presented and compared from aspects of their performances, complexity of overall structure, magnetic device capacity and power losses, etc. The necessary simulation results are given to verify and compare the effectiveness of some involved harmonic reduction methods. Based on these topologies, the advantages, drawbacks and future trends of the passive or active methods are concluded; besides, the hybrid harmonic reduction methods are also considered. This article aims to provide useful guidance for the researches of harmonic elimination and multi-pulse rectification technology.

CubeSats have been popular for space research due to lower cost, faster development, and easier deployment. The electrical power system (EPS) is one of the significant subsystem for the CubeSat since it handles power generation, energy storage, and power distribution to all other subsystems. Therefore, the design of EPS becomes crucial for successful CubeSat mission, wherein the first step is the selection of EPS architecture. The main objective of this paper is to present an extensive review of all the conventional and emerging EPS architectures of CubeSats. A total of seventeen categories of CubeSat EPS architectures have been identified, classified, and the operational aspects of these architectures are presented in addition to a qualitative comparison. This study is expected to provide a useful reference guide for all the researchers and developers working in the area of CubeSats EPS. Also, some of the potential research topics are provided to further exploration and innovation for the CubeSat EPS.

Hydrogen has shown great potential in the renewable power integration and urban mobility decarbonization like the hydrogen fuel cell vehicles (HFCVs). The HFCV refueling as an essential hydrogen load is of great flexibility. Considering the HFCV demand response, this paper studies the integrated electric power and hydrogen system (IPHS) operation. First, the HFCV refueling load model is formulated with its routing on the transportation network considered. Second, the optimal IPHS operation model is developed in which the electric power operation, tube-trailer based hydrogen delivery and HFCV refueling are coordinated. Third, a Lagrangian Relaxation (LR) based method is developed to solve the proposed model efficiently, which corresponds to a price-based demand response mechanism for HFCVs. Compared with existing works on IPHS, the influence of transportation networks is delicately analyzed on both HFCV refueling and hydrogen delivery. The case studies have proven the effectiveness of the proposed method and demonstrated that the overall operation cost is decreased via the proper guidance of HFCV refueling. The HFCV demand response shows great potential in exploring the synergy of energy and transportation systems.

This paper investigates the integration of the fractional-order capacitor on electrical power systems to improve system performance. The system performance problem in this exploration is reducing the losses and improving the voltage profile. For decades, capacitor installation is having a great effect on compensating system reactive power which affects system performance and quality. The novelty in the proposed work is to integrate the fractional capacitor to the power systems as a distributed generator. The study compares the classical capacitor implementation versus the fractional capacitor as a suggested new technology. Due to the complexity of the study to obtain optimal size, parameter, and location of the proposed technologies, Marine predator as a meta-heuristic optimization technique is employed. The proposed methodology can be divided into two parts; a single objective function to study the losses minimization and the voltage improvement individually and the second part is the multi-objective single representation problem to find the optimal solution for both two targets, the losses reduction, and the voltage profile improvement. The proposed fractional capacitor implementation is assimilated to standard IEEE 69 radial system.

The motor in high power electric vehicle (EV) easily reached at voltage limit because of its large magnetic flux. Therefore, the motor should be designed so that the voltage is controlled at the limit. To achieve well voltage control condition, the interior permanent-magnet synchronous motor (IPMSM) is controlled by the field-weakening control method after the constant torque region. This is conducted by canceling the magnetic flux from the permanent magnet with the magnetic flux of the stator winding. However, this method generates many harmonics. In this paper, a design that effectively controls the voltage by reducing the harmonics generated in the field-weakening control is proposed. To reduce the harmonics in the field-weakening region, change stator and rotor design parameters, and the reason for using v-type permanent magnet arrangement for high-speed operation will be elucidated.

Desiccant dehumidification systems are thermally regenerated systems that can be used either as standalone or as complementary additives for conventional cooling systems. One of their best competitive qualities is the potential to utilize low-grade heat sources for the regeneration process, thus decreasing electrical power consumption and scaling back the emissions of greenhouse gasses. However, up till now, desiccant dehumidification systems saw limited practical applications, due to their relatively high capital costs and low efficiency. To enhance the commercial competitiveness of desiccant dehumidification systems and expand their fairly tiny niche market, it was necessary to improve the system's performance and reliability and reduce their costs. A detailed discussion of the current designs configurations and the main differences between them may help future researchers to come up with novel, innovative designs, to overcome the system's drawbacks and make them actual viable alternative competitors in the dehumidification market. Consequently, this paper presents and analyzes the development of those configurations in the following three main aspects: packed bed, fluidized bed, and rotating desiccant wheel.

The space charge dynamic behavior and accumulation are important contributions to the formation of electrical trees, as recognized by crosslinked polyethylene (XLPE) cable insulation under alternating current electric stress. In this paper, in order to investigate the reasons for the charge accumulation phenomenon revealed by experiments under ac stress, a bipolar space charge transport model with symmetrical and asymmetrical parameters is built under AC stress. The charge accumulation mechanism is analyzed based on the variation of space charge density with different voltage application time and voltage phase. The effects of each major physical parameter are simulated and analyzed, respectively. The results show that there is no obvious space charge accumulation with the transport model under symmetrical physical parameters. However, asymmetrical parameters in the transport model result in different motions between positive and negative charges, which greatly enhances the charge accumulation. Each main parameter has an influence on charge accumulation in different perspectives and extents. The applicability of the simulation model with asymmetrical parameters is evaluated by comparing experiment and simulation results. This study contributes to the understanding of space charge generation mechanism under AC voltage and serves as a basis for improving the stability of XLPE electric power cables.