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Model for Energy Analysis of Miscanthus Production and Transportation
Alessandro Sopegno, Efthymios Rodias, Dionysis Bochtis, Patrizia Busato, Remigio Berruto, Valter Boero, Claus Sørensen
November 28, 2018 (v1)
Subject: Biosystems
Keywords: Biomass, biomass logistics, operations analysis
A computational tool is developed for the estimation of the energy requirements of Miscanthus x giganteus on individual fields that includes a detailed analysis and account of the involved in-field and transport operations. The tool takes into account all the individual involved in-field and transport operations and provides a detailed analysis on the energy requirements of the components that contribute to the energy input. A basic scenario was implemented to demonstrate the capabilities of the tool. Specifically, the variability of the energy requirements as a function of field area and field-storage distance changes was shown. The field-storage distance highly affects the energy requirements resulting in a variation in the efficiency if energy (output/input ratio) from 15.8 up to 23.7 for the targeted cases. Not only the field-distance highly affects the energy requirements but also the biomass transportation system. Based on the presented example, different transportation systems a... [more]
Development and a Validation of a Charge Sensitive Organic Rankine Cycle (ORC) Simulation Tool
Davide Ziviani, Brandon J. Woodland, Emeline Georges, Eckhard A. Groll, James E. Braun, W. Travis Horton, Martijn van den Broek, Michel De Paepe
November 28, 2018 (v1)
Keywords: charge-based solver, cycle modeling, organic Rankine cycle, scroll expander, single-screw expander
Despite the increasing interest in organic Rankine cycle (ORC) systems and the large number of cycle models proposed in the literature, charge-based ORC models are still almost absent. In this paper, a detailed overall ORC simulation model is presented based on two solution strategies: condenser subcooling and total working fluid charge of the system. The latter allows the subcooling level to be predicted rather than specified as an input. The overall cycle model is composed of independent models for pump, expander, line sets, liquid receiver and heat exchangers. Empirical and semi-empirical models are adopted for the pump and expander, respectively. A generalized steady-state moving boundary method is used to model the heat exchangers. The line sets and liquid receiver are used to better estimate the total charge of the system and pressure drops. Finally, the individual components are connected to form a cycle model in an object-oriented fashion. The solution algorithm includes a prec... [more]
Representational Learning for Fault Diagnosis of Wind Turbine Equipment: A Multi-Layered Extreme Learning Machines Approach
Zhi-Xin Yang, Xian-Bo Wang, Jian-Hua Zhong
November 28, 2018 (v1)
Keywords: autoencoder (AE), classification, extreme learning machines (ELM), fault diagnosis, wind turbine
Reliable and quick response fault diagnosis is crucial for the wind turbine generator system (WTGS) to avoid unplanned interruption and to reduce the maintenance cost. However, the conditional data generated from WTGS operating in a tough environment is always dynamical and high-dimensional. To address these challenges, we propose a new fault diagnosis scheme which is composed of multiple extreme learning machines (ELM) in a hierarchical structure, where a forwarding list of ELM layers is concatenated and each of them is processed independently for its corresponding role. The framework enables both representational feature learning and fault classification. The multi-layered ELM based representational learning covers functions including data preprocessing, feature extraction and dimension reduction. An ELM based autoencoder is trained to generate a hidden layer output weight matrix, which is then used to transform the input dataset into a new feature representation. Compared with the t... [more]
A Wavelet-Based Unified Power Quality Conditioner to Eliminate Wind Turbine Non-Ideality Consequences on Grid-Connected Photovoltaic Systems
Bijan Rahmani, Weixing Li, Guihua Liu
November 28, 2018 (v1)
Keywords: active series filter (SF), advanced generalized theory of instantaneous power (A-GTIP) theory, DC-link, load-terminal voltage, low–pass filter (LPF), phase locked loop (PLL), source current, synchronous reference frame (SRF) theory, unified power quality conditioner (UPQC), wavelet
The integration of renewable power sources with power grids presents many challenges, such as synchronization with the grid, power quality problems and so on. The shunt active power filter (SAPF) can be a solution to address the issue while suppressing the grid-end current harmonics and distortions. Nonetheless, available SAPFs work somewhat unpredictably in practice. This is attributed to the dependency of the SAPF controller on nonlinear complicated equations and two distorted variables, such as load current and voltage, to produce the current reference. This condition will worsen when the plant includes wind turbines which inherently produce 3rd, 5th, 7th and 11th voltage harmonics. Moreover, the inability of the typical phase locked loop (PLL) used to synchronize the SAPF reference with the power grid also disrupts SAPF operation. This paper proposes an improved synchronous reference frame (SRF) which is equipped with a wavelet-based PLL to control the SAPF, using one variable such... [more]
Online Diagnosis for the Capacity Fade Fault of a Parallel-Connected Lithium Ion Battery Group
Hua Zhang, Lei Pei, Jinlei Sun, Kai Song, Rengui Lu, Yongping Zhao, Chunbo Zhu, Tiansi Wang
November 27, 2018 (v1)
Keywords: capacity fade, fault simulation, online fault diagnosis, parallel-connected battery group, recursive least squares algorithm with restricted memory and constraint
In a parallel-connected battery group (PCBG), capacity degradation is usually caused by the inconsistency between a faulty cell and other normal cells, and the inconsistency occurs due to two potential causes: an aging inconsistency fault or a loose contacting fault. In this paper, a novel method is proposed to perform online and real-time capacity fault diagnosis for PCBGs. Firstly, based on the analysis of parameter variation characteristics of a PCBG with different fault causes, it is found that PCBG resistance can be taken as an indicator for both seeking the faulty PCBG and distinguishing the fault causes. On one hand, the faulty PCBG can be identified by comparing the PCBG resistance among PCBGs; on the other hand, two fault causes can be distinguished by comparing the variance of the PCBG resistances. Furthermore, for online applications, a novel recursive-least-squares algorithm with restricted memory and constraint (RLSRMC), in which the constraint is added to eliminate the “i... [more]
Cathode Assessment for Maximizing Current Generation in Microbial Fuel Cells Utilizing Bioethanol Effluent as Substrate
Guotao Sun, Anders Thygesen, Anne S. Meyer
November 27, 2018 (v1)
Subject: Biosystems
Keywords: air cathode (AiC), bioethanol effluent, dissolved oxygen cathode (DOC), electrochemical impedance spectroscopy (EIS), ferricyanide cathode (FeC)
Implementation of microbial fuel cells (MFCs) for electricity production requires effective current generation from waste products via robust cathode reduction. Three cathode types using dissolved oxygen cathodes (DOCs), ferricyanide cathodes (FeCs) and air cathodes (AiCs) were therefore assessed using bioethanol effluent, containing 20.5 g/L xylose, 1.8 g/L arabinose and 2.5 g/L propionic acid. In each set-up the anode and cathode had an electrode surface area of 88 cm², which was used for calculation of the current density. Electricity generation was evaluated by quantifying current responses to substrate loading rates and external resistance. At the lowest external resistance of 27 Ω and highest substrate loading rate of 2 g chemical oxygen demand (COD) per L·day, FeC-MFC generated highest average current density (1630 mA/m²) followed by AiC-MFC (802 mA/m²) and DOC-MFC (184 mA/m²). Electrochemical impedance spectroscopy (EIS) was used to determine the impedance of the cathodes. It w... [more]
Cobalt-Based Electrolytes for Dye-Sensitized Solar Cells: Recent Advances towards Stable Devices
Federico Bella, Simone Galliano, Claudio Gerbaldi, Guido Viscardi
November 27, 2018 (v1)
Subject: Materials
Keywords: cobalt complex, cobalt electrolyte, dye-sensitized solar cell, polymer electrolyte, quasi-solid electrolyte, stability
Redox mediators based on cobalt complexes allowed dye-sensitized solar cells (DSCs) to achieve efficiencies exceeding 14%, thus challenging the emerging class of perovskite solar cells. Unfortunately, cobalt-based electrolytes demonstrate much lower long-term stability trends if compared to the traditional iodide/triiodide redox couple. In view of the large-scale commercialization of cobalt-based DSCs, the scientific community has recently proposed various approaches and materials to increase the stability of these devices, which comprise gelling agents, crosslinked polymeric matrices and mixtures of solvents (including water). This review summarizes the most significant advances recently focused towards this direction, also suggesting some intriguing way to fabricate third-generation cobalt-based photoelectrochemical devices stable over time.
Modelling, Testing and Analysis of a Regenerative Hydraulic Shock Absorber System
Ruichen Wang, Fengshou Gu, Robert Cattley, Andrew D. Ball
November 27, 2018 (v1)
Keywords: Modelling, parameter identification, power regeneration, shock absorber, suspension
To improve vehicle fuel economy whilst enhancing road handling and ride comfort, power generating suspension systems have recently attracted increased attention in automotive engineering. This paper presents our study of a regenerative hydraulic shock absorber system which converts the oscillatory motion of a vehicle suspension into unidirectional rotary motion of a generator. Firstly a model which takes into account the influences of the dynamics of hydraulic flow, rotational motion and power regeneration is developed. Thereafter the model parameters of fluid bulk modulus, motor efficiencies, viscous friction torque, and voltage and torque constant coefficients are determined based on modelling and experimental studies of a prototype system. The model is then validated under different input excitations and load resistances, obtaining results which show good agreement between prediction and measurement. In particular, the system using piston-rod dimensions of 50⁻30 mm achieves recovera... [more]
A Study on Price-Based Charging Strategy for Electric Vehicles on Expressways
Lixing Chen, Zhong Chen, Xueliang Huang, Long Jin
November 27, 2018 (v1)
Keywords: electric vehicles (EVs), expressway, price-based charging, queueing algorithm
With the large-scale adoption of electric vehicles (EVs) on expressways, the exploration of a guiding-based charging method to effectively adjust interactions between EVs and the fast charging stations (CSs) is urgently needed. This paper proposes a status-of-use (SOU) price-based charging strategy that can motivate users to charge in advance. A queuing model for a CS cluster was established to verify the effectiveness of the strategy, and then a simulation of traveling and charging conditions of 12,000 pure EVs on the road network from 0:00 to 24:00 was performed according to the related data and using the Monte Carlo method, the Floyd-Warshall algorithm, and the queuing algorithm proposed in this paper. Compared to unordered charging (UC), SOU price-based charging can not only reduce the charging cost and waiting time for users, but also increase the utilization ratio of charging facilities in a CS cluster and thus lower their influence on the power grid and expressway traffic. SOU p... [more]
An Intelligent Sensor for the Ultra-High-Frequency Partial Discharge Online Monitoring of Power Transformers
Jian Li, Xudong Li, Lin Du, Min Cao, Guochao Qian
November 27, 2018 (v1)
Keywords: field programmable gate array (FPGA), high-speed voltage comparator, intelligent sensor, level scanning method, online monitoring, partial discharge (PD), ultra-high-frequency (UHF)
Ultra-high-frequency (UHF) partial discharge (PD) online monitoring is an effective way to inspect potential faults and insulation defects in power transformers. The construction of UHF PD online monitoring system is a challenge because of the high-frequency and wide-frequency band of the UHF PD signal. This paper presents a novel, intelligent sensor for UHF PD online monitoring based on a new method, namely a level scanning method. The intelligent sensor can directly acquire the statistical characteristic quantities and is characterized by low cost, few data to output and transmit, Ethernet functionality, and small size for easy installation. The prototype of an intelligent sensor was made. Actual UHF PD experiments with three typical artificial defect models of power transformers were carried out in a laboratory, and the waveform recording method and intelligent sensor proposed were simultaneously used for UHF PD measurement for comparison. The results show that the proposed intellig... [more]
Comparative Study of the Subsurface Thermal Structure in Northern Honshu, Japan, Based on Normalized Temperature Data and Solute Geothermometers
Yota Suzuki, Seiichiro Ioka, Hirofumi Muraoka
November 27, 2018 (v1)
Subject: Energy Policy
Keywords: activity index, geothermal database, geothermal energy, geothermal exploration, geothermal mapping, geothermometry, volcanic front
To promote geothermal development in Aomori Prefecture, Japan, this study compiled a database of the geothermal resources of the prefecture, which included chemical data for 786 hot springs, temperature data for 26 natural springs, and subsurface temperature data for 35 wells. A map of the activity index distribution for the entire prefecture was also developed using the Aomori Prefecture Geothermal Resource database, and its efficiency was discussed by comparison with the distribution of Quaternary volcanoes and the temperature distribution map calculated using quartz and Na-K solute geothermometers. The activity index distribution map for the entire prefecture showed a good fit with both the distribution map of a region with a sharp eastern edge of low-velocity zones in the mantle wedge and the volcanic front, as well as the temperature distribution map calculated using the quartz and Na-K geothermometers. This reflected the effectiveness of the developed map, which indicated the Hak... [more]
An Event-Triggered Online Energy Management Algorithm of Smart Home: Lyapunov Optimization Approach
Wei Fan, Nian Liu, Jianhua Zhang
November 27, 2018 (v1)
Keywords: energy management, event triggering, Lyapunov optimization, smart home
As an important component of the smart grid on the user side, a home energy management system is the core of optimal operation for a smart home. In this paper, the energy scheduling problem for a household equipped with photovoltaic devices was investigated. An online energy management algorithm based on event triggering was proposed. The Lyapunov optimization method was adopted to schedule controllable load in the household. Without forecasting related variables, real-time decisions were made based only on the current information. Energy could be rapidly regulated under the fluctuation of distributed generation, electricity demand and market price. The event-triggering mechanism was adopted to trigger the execution of the online algorithm, so as to cut down the execution frequency and unnecessary calculation. A comprehensive result obtained from simulation shows that the proposed algorithm could effectively decrease the electricity bills of users. Moreover, the required computational... [more]
Analysis and Minimization of Output Current Ripple for Discontinuous Pulse-Width Modulation Techniques in Three-Phase Inverters
Gabriele Grandi, Jelena Loncarski, Milan Srndovic
November 27, 2018 (v1)
Keywords: harmonic distortion, inverters, pulse-width modulation (PWM), ripple minimization
This paper gives the complete analysis of the output current ripple in three-phase voltage source inverters considering the different discontinuous pulse-width modulation (DPWM) strategies. In particular, peak-to-peak current ripple amplitude is analytically evaluated over the fundamental period and compared among the most used DPWMs, including positive and negative clamped (DPWM+ and DPWM−), and the four possible combinations between them, usually named as DPWM0, DPWM1, DPWM2, and DPWM3. The maximum and the average values of peak-to-peak current ripple are estimated, and a simple method to correlate the ripple envelope with the ripple rms is proposed and verified. Furthermore, all the results obtained by DPWMs are compared to the centered pulse-width modulation (CPWM, equivalent to the space vector modulation) to identify the optimal pulse-width modulation (PWM) strategy as a function of the modulation index, taking into account the different average switching frequency. In this way,... [more]
Adaptive Protection Scheme for a Distribution System Considering Grid-Connected and Islanded Modes of Operation
Yavuz Ates, Ali Rifat Boynuegri, Mehmet Uzunoglu, Abdullah Nadar, Recep Yumurtacı, Ozan Erdinc, Nikolaos G. Paterakis, João P. S. Catalão
November 27, 2018 (v1)
Keywords: adaptive protection, distributed generation (DG), relay coordination, smart grid
The renewable energy-based distributed generation (DG) implementation in power systems has been an active research area during the last few decades due to several environmental, economic and political factors. Although the integration of DG offers many advantages, several concerns, including protection schemes in systems with the possibility of bi-directional power flow, are raised. Thus, new protection schemes are strongly required in power systems with a significant presence of DG. In this study, an adaptive protection strategy for a distribution system with DG integration is proposed. The proposed strategy considers both grid-connected and islanded operating modes, while the adaptive operation of the protection is dynamically realized considering the availability of DG power production (related to faults or meteorological conditions) in each time step. Besides, the modular structure and fast response of the proposed strategy is validated via simulations conducted on the IEEE 13-node... [more]
A Novel Single Winding Structure and Closed Loop Control of the Suspension Force Vector of Bearingless Permanent Magnet Synchronous Motors
Huangqiu Zhu, Jianfei Yuan, Jintao Jv
November 27, 2018 (v1)
Keywords: bearingless permanent magnet synchronous motors (BPMSM), closed loop control of suspension force vector, finite element analysis (FEA), simulation and experiment, T-shaped single winding configuration
At present, because of their advantages of simple structure, low cost, low power consumption and high efficiency, single winding bearingless permanent magnet synchronous motors (SBPMSMs) have become one of the research hotspots in the bearingless technology field. However, a high motional-electromotive force (EMF) is generated by rotor rotation in the single winding, which already has side-effects on the normal suspension force current, and the suspension force response can be delayed. Because the method of double torque current inverse injection in the symmetrical winding allows the motional-EMFs of the corresponding phase windings to offset each other in the opposite direction, with no adverse effects on original performance, a T-shaped single winding configuration is proposed to realize precisely that effect. In this paper, the analytical expressions of the radial suspension force and torque are deduced and the motional-EMF and performance are analyzed by finite element method using... [more]
Telecommunication Technologies for Smart Grid Projects with Focus on Smart Metering Applications
Nikoleta Andreadou, Miguel Olariaga Guardiola, Gianluca Fulli
November 27, 2018 (v1)
Keywords: smart grid, smart grid projects, smart metering solutions, telecommunication technologies
This paper provides a study of the smart grid projects realised in Europe and presents their technological solutions with a focus on smart metering Low Voltage (LV) applications. Special attention is given to the telecommunications technologies used. For this purpose, we present the telecommunication technologies chosen by several European utilities for the accomplishment of their smart meter national roll-outs. Further on, a study is performed based on the European Smart Grid Projects, highlighting their technological options. The range of the projects analysed covers the ones including smart metering implementation as well as those in which smart metering applications play a significant role in the overall project success. The survey reveals that various topics are directly or indirectly linked to smart metering applications, like smart home/building, energy management, grid monitoring and integration of Renewable Energy Sources (RES). Therefore, the technological options that lie be... [more]
Fabrication and Characterization of CH₃NH₃PbI3−x−yBrxCly Perovskite Solar Cells
Atsushi Suzuki, Hiroshi Okada, Takeo Oku
November 27, 2018 (v1)
Subject: Materials
Keywords: crystal structure, microstructure, perovskite, photovoltaic property, solar cell
Fabrication and characterization of CH₃NH₃PbI3−x−yBrxCly perovskite solar cells using mesoporous TiO₂ as electron transporting layer and 2,2′,7,7′-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9′-spirobifluorene as a hole-transporting layer (HTL) were performed. The purpose of the present study is to investigate role of halogen doping using iodine (I), bromine (Br) and chlorine (Cl) compounds as dopant on the photovoltaic performance and microstructures of CH₃NH₃PbI3−x−yBrxCly perovskite solar cells. The X-ray diffraction identified a slight decrease of crystal spacing in the perovskite crystal structure doped with a small amount of I, Br, and Cl in the perovskite compounds. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) showed the perovskite crystal behavior depended on molar ratio of halogen of Pb, I, Br and Cl. Incorporation of the halogen doping into the perovskite crystal structure improved photo generation, carrier diffusion without carrier recombina... [more]
Nanostructured p-Type Semiconductor Electrodes and Photoelectrochemistry of Their Reduction Processes
Matteo Bonomo, Danilo Dini
November 27, 2018 (v1)
Subject: Other
Keywords: CO2 reduction, dye-sensitized solar cell, metal chalcogenides, metal oxides, p-type, photoelectrochemistry, reduction, semiconductor, solar fuels
This review reports the properties of p-type semiconductors with nanostructured features employed as photocathodes in photoelectrochemical cells (PECs). Light absorption is crucial for the activation of the reduction processes occurring at the p-type electrode either in the pristine or in a modified/sensitized state. Beside thermodynamics, the kinetics of the electron transfer (ET) process from photocathode to a redox shuttle in the oxidized form are also crucial since the flow of electrons will take place correctly if the ET rate will overcome that one of recombination and trapping events which impede the charge separation produced by the absorption of light. Depending on the nature of the chromophore, i.e., if the semiconductor itself or the chemisorbed dye-sensitizer, different energy levels will be involved in the cathodic ET process. An analysis of the general properties and requirements of electrodic materials of p-type for being efficient photoelectrocatalysts of reduction proce... [more]
Chemical Analysis of Different Parts of Date Palm (Phoenix dactylifera L.) Using Ultimate, Proximate and Thermo-Gravimetric Techniques for Energy Production
Ramadan A. Nasser, Mohamed Z. M. Salem, Salim Hiziroglu, Hamad A. Al-Mefarrej, Ahmed S. Mohareb, Manawwer Alam, Ibrahim M. Aref
November 27, 2018 (v1)
Subject: Materials
Keywords: date palm, Energy, proximate analysis, thermo-gravimatric analysis, ultamiate analysis
The objective of the study was to analyze chemical structure of date palm (Phoenix dactylifera L.) by employing ultimate, proximate and thermo-gravimetric techniques. Samples from different anatomical parts of date palm, namely trunk, frond base, frond midrib, leaflets, coir, fruit stem, date stone, and fruit empty bunches were considered for the experiments. Based on the findings in this work palm leaflet samples gave the highest amount of extractives content (32.9%), followed by date palm stone specimens with 31.5%. Cellulose content values of 32.8% and 47.5% were obtained for date palm stone and palm coir samples, respectively. Overall the hemicellulose contents of all samples were relatively similar to those of typical wood or non-wood lignocellulosic materials with the two exceptions of palm coir and palm leaflets. Both palm coir and palm leaflet specimens had 12.6% and 16.1% hemicellulose content. Volatile matter values of 74.3% and 87.5% were determined for leaflets and fruit em... [more]
Black Start Strategy for PV-ESS Multi-Microgrids with Three-Phase/Single-Phase Architecture
Zhirong Xu, Ping Yang, Zhiji Zeng, Jiajun Peng, Zhuoli Zhao
November 27, 2018 (v1)
Keywords: black start, distributed restoration, hierarchical control, multi-microgrids
With the rapid development of microgrids (MGs) in recent years, it is anticipated that combinations of multiple microgrids—multi-microgrids (MMGs)—will gradually become a new form of power grid. A safe and efficient black start strategy for MMGs is in urgent demand because of their complicated structure and control systems. In this paper, first, we analyze the topology and control system of residential-type MMGs with three-phase/single-phase (TP/SP) architecture. Second, a black start strategy based on a hierarchical control scheme is presented, including the selection strategy for the main power supply and master microgrid, the stand-alone operation strategy, and the grid-connected operation strategy. After the selection of the main power supplies, the master MG is determined. Hereby, all sub-microgrids (SMGs) execute the stand-alone algorithm. When the synchronous connection condition is satisfied, the slave SMGs connect to the master MG who provides the voltage and frequency support... [more]
Assessment of the Variability of Biogas Production from Sugar Beet Silage as Affected by Movement and Loss of the Produced Alcohols and Organic Acids
Ali Heidarzadeh Vazifehkhoran, Jin Mi Triolo, Søren Ugilt Larsen, Kasper Stefanek, Sven G. Sommer
November 27, 2018 (v1)
Subject: Biosystems
Keywords: anaerobic digestion, Beta vulgaris, biomethanation, ensiling, organic components, Renewable and Sustainable Energy
The biochemical methane potential and composition of sugar beet pulp silage were investigated using samples taken from six different depths in both open and closed silos (height 3.6 m). The biochemical methane potential (BMP) of pulp silage in open silos ranged from 337 to 420 normal litre (NL) CH₄/kg volatile solids (VS), while the BMP of pulp silage in closed silos varied between 411 and 451 NL CH₄/kg VS. The biochemical methane potential peaked at a depth of 1.45 m with 420 NL CH₄/kg VS for open silos and 451 NL CH₄/kg VS for closed silos. The ethanol concentration and biochemical methane potential showed the same trend with depth throughout the silos. The energy loss correlated to the loss of volatile solids, and the depths described a linear relationship between them for both the open and closed silos (R² = 0.997 for the open silo and R² = 0.991 for the closed silo). The energy potentials and composition of beet pulp silage were highly stratified and there was a risk that the sila... [more]
Experimental Attempts to Investigate the Influence of Petrographic Properties on Drying Characteristics of Lignite in Superheated Steam Atmosphere
Anna Sciazko, Yosuke Komatsu, Marcin Zakrzewski, Taro Akiyama, Akira Hashimoto, Naoki Shikazono, Shozo Kaneko, Shinji Kimijima, Janusz S. Szmyd, Yoshinori Kobayashi
November 27, 2018 (v1)
Keywords: drying characteristic, lignite upgrading, low-rank coal (LRC), superheated steam drying, Turow lignite
A superheated steam fluidized bed dryer (SSFBD) in a self-heat recuperative configuration has a great potential of improving thermal efficiency of a lignite-fired power plant by recovering both of latent heat of vaporization of water kept in the fuel and part of sensible heat during the fuel processing. However, the optimal design of the dryer requires the fundamental knowledge of drying characteristics in respect to the individual properties of the utilized fuel. Experimental investigation to determine the correlation between a specific coal properties originated from geological background and its drying characteristics is thus the major concern in this paper. The investigated lignite is a representative of Turoszow deposit in Poland. Experimental attempts unveiling drying kinetics were carried out for 5 mm and 10 mm diameter spherical samples in the superheated steam atmosphere in the temperature range of 110 °C⁻170 °C. Simultaneous and continuous measurements of changes in weight, s... [more]
Effects of Different Factors on Electrical Equipment UV Corona Discharge Detection
Zhenyu Li, Licheng Li, Xingliang Jiang, Jianlin Hu, Zhijin Zhang, Wei Zhang
November 27, 2018 (v1)
Subject: Other
Keywords: corona discharge, correction, gain, observation angle, observation distance, photon number, UV imaging
As a non-contact discharge detection method, ultraviolet (UV) imaging can rapidly, directly, and securely detect corona discharges. Therefore, UV imaging has been widely applied to power systems. To study the influences of different factors on UV corona discharge detection, two typical types of UV imagers (DayCor®Superb and CoroCAM®6D) were utilized. Results show that the observation angle has little impact on UV detection if no obstacles block the detection line of sight. Given that different UV imagers have different optimal imager gains, photon numbers under different gains could be calibrated to the values under optimal gains in accordance with the gain correction formula. Photon numbers decrease with the increase in the square of observation distance. Detection results under different observation distances could be corrected to the contrast distance after the detection of electrical equipment. The photon numbers of different UV imager types could be corrected in accordance with th... [more]
A Multi-Period Framework for Coordinated Dispatch of Plug-in Electric Vehicles
Yinuo Huang, Chuangxin Guo, Yi Ding, Licheng Wang, Bingquan Zhu, Lizhong Xu
November 27, 2018 (v1)
Keywords: day-ahead dispatch, interval optimization, PEV-clustered model, plug-in electric vehicles (PEVs), priority-ordering method, real-time dispatch
Coordinated dispatch of plug-in electric vehicles (PEVs) with renewable energies has been proposed in recent years. However, it is difficult to achieve effective PEV dispatch with a win-win result, which not only optimizes power system operation, but also satisfies the requirements of PEV owners. In this paper, a multi-period PEV dispatch framework, combining day-ahead dispatch with real-time dispatch, is proposed. On the one hand, the day-ahead dispatch is used to make full use of wind power and minimize the fluctuation of total power in the distribution system, and schedule the charging/discharging power of PEV stations for each period. On the other hand, the real-time dispatch arranges individual PEVs to meet the charging/discharging power demands of PEV stations given by the day-ahead dispatch. To reduce the dimensions of the resulting large-scale, non-convex problem, PEVs are clustered according to their travel information. An interval optimization model is introduced to obtain th... [more]
How Much Detail Should We Use to Compute Societal Aggregated Exergy Efficiencies?
Miguel Palma, Tânia Sousa, Zeus Guevara
November 27, 2018 (v1)
Subject: Energy Policy
Keywords: efficiency, Energy, energy carriers, energy use, Exergy, useful exergy
The current method used for calculating societal aggregated exergy efficiencies is reviewed. Cooling is introduced as an end-use category; conversion efficiencies for heating processes are obtained for each energy carrier; and electricity shares per end-use are retrieved for each sector, improving the accuracy of the estimated values of aggregated exergy efficiencies. We show that: (1) cooling uses are a relevant end-use in Portugal and that their introduction decreased overall efficiency by 3.4% in 2009; and (2) disaggregating the heating second law efficiencies for each energy carrier has a significant effect on the aggregated efficiencies of the country, decreasing aggregated efficiency by 1.3% in 2009. We studied two other factors that showed no significant impact on aggregated exergy efficiency: a technological lag of 10 years in the efficiency of stationary mechanical drive devices and the use of a year-specific ambient temperature to compute exergy efficiencies of heating proces... [more]
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