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Records with Subject: Process Operations
Showing records 151 to 175 of 710. [First] Page: 3 4 5 6 7 8 9 10 11 Last
Two-Stage Fuzzy Logic Inference Algorithm for Maximizing the Quality of Performance under the Operational Constraints of Power Grid in Electric Vehicle Parking Lots
Shahid Hussain, Ki-Beom Lee, Mohamed A. Ahmed, Barry Hayes, Young-Chon Kim
April 3, 2023 (v1)
Keywords: electric vehicles, fuzzy logic inference, parking lot, quality of experience, quality of performance
The widespread adoption of electric vehicles (EVs) has entailed the need for the parking lot operators to satisfy the charging and discharging requirements of all the EV owners during their parking duration. Meanwhile, the operational constraints of the power grids limit the amount of simultaneous charging and discharging of all EVs. This affects the EV owner’s quality of experience (QoE) and thereby reducing the quality of performance (QoP) for the parking lot operators. The QoE represents a certain percentage of the EV battery required for its next trip distance; whereas, the QoP refers to the ratio of EVs with satisfied QoE to the total number of EVs during the operational hours of the parking lot. This paper proposes a two-stage fuzzy logic inference based algorithm (TSFLIA) to schedule the charging and discharging operations of EVs in such a way that maximizes the QoP for the parking lot operators under the operational constraints of the power grid. The first stage fuzzy inference... [more]
Optimizing Parallel Pumping Station Operations in an Open-Channel Water Transfer System Using an Efficient Hybrid Algorithm
Xiaoli Feng, Baoyun Qiu, Yongxing Wang
April 3, 2023 (v1)
Keywords: discharge distribution, energy savings, hybrid algorithm, open-channel water transfer system, optimizing operation, parallel pumping stations
This article presents a methodology for optimizing the operation of parallel pumping stations in an open-channel water transfer system. A mathematical model was established for the minimum power with constraints on water level, flow rate and pump unit performance, and related factors. In the objective function, energy consumption of relevant equipment or facilities, such as main pump units, power transmission and transformation equipment, and auxiliary equipment, was considered comprehensively. The model was decomposed to two layers for solving. In the first layer, by using discharge distribution ratio as a variable, the flow rate and water level of the two water channels could be determined by employing the dichotomy approach (DA), and were calculated according to the principle of energy conservation, considering energy loss caused by hydraulic leakage and evaporation losses. In the second layer, the number of running pumps and the flow rate of a single pump were obtained by simulated... [more]
Degraded Trees from Spruce Budworm Epidemics as Bioenergy Feedstock: A Profitability Analysis of Forest Operations
Mathieu Béland, Evelyne Thiffault, Julie Barrette, Warren Mabee
April 3, 2023 (v1)
Keywords: costs, forest biomass, natural disturbances, silviculture, wood pellets
Natural disturbances are common in Canadian boreal managed forests. For example, during and after insect epidemics, foresters must deal with significant amounts of degraded or dead wood that cannot be processed into sawn timber or pulp. Bioenergy could be an alternative pathway for this wood. A case study in Quebec (Canada) was used to evaluate the profitability of pellet production for bioenergy using degraded trees from insect epidemics. A bioenergy scenario was simulated in which degraded trees were harvested for bioenergy alongside sound wood for timber and pulp. This scenario was compared to a reference scenario in which degraded trees were left on cutovers. Using wood pellets as a case study, the results showed that at current market prices, harvesting degraded trees for pellet production is not as profitable as leaving them in the forest. Nevertheless, the overall forest operations for procuring wood for timber and pulp were still profitable, even with very high degradation leve... [more]
Energy Inputs in Motor-Manual Release Cutting of Broadleaved Forests: Results of Twelve Options
Nicuşor Boja, Stelian Alexandru Borz
April 3, 2023 (v1)
Keywords: balance, Energy, forestry, input, motor-manual, operations, release cutting
Lignocellulosic biomass is used in various industries and its procurement involves a set of operations that are mainly done using equipment powered by internal combustion engines. The sustainability of forest operations may be characterized by balancing their energy inputs with those typically embodied in their outputted products. Forest tending operations are problematic because most of them cannot output marketable products while the data on their energy inputs are important for the forest management. Six of the most commonly used brushcutters equipped successively with discs and knives were tested to provide part of the data needed to run an energy analysis and to be able to characterize the energy inputs in release cutting operations by implementing the Gross Energy Requirements method. Fuel burning was found to have the greatest contribution (83−92%) in the total energy inputs (0.8−1.2 GJ/ha) of the studied operations and it was highly dependent on the efficiency of operations. Mo... [more]
On-Line Diagnosis and Fault State Classification Method of Photovoltaic Plant
Jun-Hyun Shin, Jin-O Kim
April 3, 2023 (v1)
Keywords: health index, Machine Learning, on-line diagnosis, operation and maintenance, photovoltaic plant, reliability
This paper presents an on-line diagnosis method for large photovoltaic (PV) power plants by using a machine learning algorithm. Most renewable energy output power is decreased due to the lack of management tools and the skills of maintenance engineers. Additionally, many photovoltaic power plants have a long down-time due to the absence of a monitoring system and their distance from the city. The IEC 61724-1 standard is a Performance Ratio (PR) index that evaluates the PV power plant performance and reliability. However, the PR index has a low recognition rate of the fault state in conditions of low irradiation and bad weather. This paper presents a weather-corrected index, linear regression method, temperature correction equation, estimation error matrix, clearness index and proposed variable index, as well as a one-class Support Vector Machine (SVM) method and a kernel technique to classify the fault state and anomaly output power of PV plants.
A Multi-Agent NILM Architecture for Event Detection and Load Classification
André Eugenio Lazzaretti, Douglas Paulo Bertrand Renaux, Carlos Raimundo Erig Lima, Bruna Machado Mulinari, Hellen Cristina Ancelmo, Elder Oroski, Fabiana Pöttker, Robson Ribeiro Linhares, Lucas da Silva Nolasco, Lucas Tokarski Lima, Júlio Shigeaki Omori, Rodrigo Braun dos Santos
March 31, 2023 (v1)
Keywords: event detection, feature extraction, load classification, NILM, NILM architecture, non-intrusive load monitoring
A multi-agent architecture for a Non-Intrusive Load Monitoring (NILM) solution is presented and evaluated. The underlying rationale for such an architecture is that each agent (load event detection, feature extraction, and classification) outperforms others of the same type in particular scenarios; hence, by combining the expertise of these agents, the system presents an improved performance. Known NILM algorithms, as well as new algorithms, proposed by the authors, were individually evaluated and compared. The proposed architecture considers a NILM system composed of Load Monitoring Modules (LMM) that report to a Center of Operations, required in larger facilities. For the purposed of evaluating and comparing performance, five load event detect agents, five feature extraction agents, and five classification agents were studied so that the best combinations of agents could be implemented in LMMs. To evaluate the proposed system, the COOLL and the LIT-Dataset were used. Performance impr... [more]
Benchmarks for Embodied and Operational Energy Assessment of Hellenic Single-Family Houses
Elena G. Dascalaki, Poulia A. Argiropoulou, Constantinos A. Balaras, Kalliopi G. Droutsa, Simon Kontoyiannidis
March 31, 2023 (v1)
Keywords: benchmarks, embodied energy, embodied energy intensity (EEI), energy recovery time, energy use intensity (EUI), operational energy, renovations, single-family houses
Building energy performance benchmarking increases awareness and enables stakeholders to make better informed decisions for designing, operating, and renovating sustainable buildings. In the era of nearly zero energy buildings, the embodied energy along with operational energy use are essential for evaluating the environmental impacts and building performance throughout their lifecycle. Key metrics and baselines for the embodied energy intensity in representative Hellenic houses are presented in this paper. The method is set up to progressively cover all types of buildings. The lifecycle analysis was performed using the well-established SimaPro software package and the EcoInvent lifecycle inventory database, complemented with national data from short energy audits carried out in Greece. The operational energy intensity was estimated using the national calculation engine for assessing the building’s energy performance and the predictions were adapted to obtain more realistic estimates.... [more]
Energy Management in the Operation of Enterprises in the Light of the Applicable Provisions of the Energy Efficiency Directive (2012/27/EU)
Katarzyna Grondys, Armenia Androniceanu, Zdzisława Dacko-Pikiewicz
March 31, 2023 (v1)
Keywords: Energy Efficiency, energy management, enterprise management
One of the ways to sustain development is striving for energy efficiency. This is the purpose of directive 2012/27/EU on energy efficiency, which aims at explaining and promoting energy−saving and ecological solutions that allow increasing the output of consumed energy. Several years after implementation, it is possible to assess the directive’s usefulness and completeness in a few areas of the economy, in particular in the operation of enterprises, which substantially contribute to the global energy consumption. Therefore, the purpose of the study was defined as an assessment of the execution of the concept of energy efficiency in business operations in EU countries, in accordance with the assumptions of directive 2012/27/EU. The collected raw data were derived from surveys gathered in the process of public consultations of the European Commission regard directive 2012/27/EU on energy efficiency. Resulting observations were analysed using the basic methods of descriptive statistics, a... [more]
Comparative of Power Calculation Methods for Single-Phase Systems under Sinusoidal and Non-Sinusoidal Operation
Alonso de Jesús Chica Leal, César Leonardo Trujillo Rodríguez, Francisco Santamaria
March 31, 2023 (v1)
Keywords: power measurement, power system harmonics, Q measurement, reactive power
This article presents a comparative experimental evaluation of some power calculation methods used for three-phase and single-phase systems. In order to make the comparison, methods based on three reference frames, the natural one, αβ and dq, are considered. This paper addresses the experimental comparison for single-phase systems facing sinusoidal and non-sinusoidal waveforms in both linear and non-linear loads. The results are obtained from an experimental platform consisting of a controlled voltage inverter and an acquisition system based on a TMS320F28335, where the power calculation algorithms are implemented. The experimental comparison of the different methods for active and reactive power calculation is made in terms of accuracy and processing time in digital implementation.
A Comparative Study of GaN HEMT and Si MOSFET-Based Active Clamp Forward Converters
Xiaobin Li, Hongbo Ma, Junhong Yi, Song Lu, Jianping Xu
March 29, 2023 (v1)
Keywords: active clamp forward converter, GaN HEMT, high-efficiency, synchronous rectification
Compared with conventional forward converters, active clamp forward (ACF) converters have many advantages, including lower voltage stress on the primary power devices, the ability to switch at zero voltage, reduced EMI and duty cycle operation above 50%. Thus, it has been the most popular solution for the low bus voltage applications, such as 48 V and 28 V. However, because of the poor performance of Si MOSFETs, the efficiency of active clamp forward converters is difficult to further improved. Focusing on the bus voltage of 28 V with 18~36 V voltage range application, the Gallium Nitride high electron-mobility transistors (GaN HEMT) with ultralow on-resistance, low parasitic capacitances, and no reverse recovery, is incorporated into active clamp forward converters for achieving higher efficiency and power density, in this paper. Meanwhile, the comparative analysis is performed for Si MOSFET and GaN HEMT. In order to demonstrate the feasibility and validity of the proposed solution an... [more]
Multi-Step Ahead Short-Term Load Forecasting Using Hybrid Feature Selection and Improved Long Short-Term Memory Network
Shaoqian Pei, Hui Qin, Liqiang Yao, Yongqi Liu, Chao Wang, Jianzhong Zhou
March 29, 2023 (v1)
Keywords: hybrid feature selection, Improved Long Short-Term Memory network, Max-Relevance and Min-Redundancy, multi-step ahead load, short-term load forecasting
Short-term load forecasting (STLF) plays an important role in the economic dispatch of power systems. Obtaining accurate short-term load can greatly improve the safety and economy of a power grid operation. In recent years, a large number of short-term load forecasting methods have been proposed. However, how to select the optimal feature set and accurately predict multi-step ahead short-term load still faces huge challenges. In this paper, a hybrid feature selection method is proposed, an Improved Long Short-Term Memory network (ILSTM) is applied to predict multi-step ahead load. This method firstly takes the influence of temperature, humidity, dew point, and date type on the load into consideration. Furthermore, the maximum information coefficient is used for the preliminary screening of historical load, and Max-Relevance and Min-Redundancy (mRMR) is employed for further feature selection. Finally, the selected feature set is considered as input of the model to perform multi-step ahe... [more]
New Infeed Correction Methods for Distance Protection in Distribution Systems
Fahd Hariri, Mariesa Crow
March 29, 2023 (v1)
Keywords: distance relay, distributed generation, faults, infeed effect, protection, PSCAD
The reliability and security of power systems may be jeopardized by the increase in the amounts of renewable generation and the uncertainties produced by these devices. In particular, the protection schemes of traditional power systems have been challenged by the integration of distributed generation (DG) resources. Distance relays (DRs), which have been mainly employed to protect transmission systems, are increasingly proposed as one of the solutions to protect distribution systems with a heavy penetration of DGs. However, conventional distance protection faces several drawbacks that might lead to maloperation. One of those challenges is the “infeed effect”, which causes the impedance seen by the distance relay to be larger than the actual positive-sequence line impedance between the fault and relay location. This paper proposes three new methods to estimate the distance to the fault in the presence of infeeds, whether in a radial distribution feeder or the transmission line. Unlike o... [more]
High-Gain High-Efficiency DC−DC Converter with Single-Core Parallel Operation Switched Inductors and Rectifier Voltage Multiplier Cell
Eduardo Augusto Oliveira Barbosa, Márcio Rodrigo Santos de Carvalho, Leonardo Rodrigues Limongi, Marcelo Cabral Cavalcanti, Eduardo José Barbosa, Gustavo Medeiros de Souza Azevedo
March 28, 2023 (v1)
Keywords: high efficiency, high gain DC–DC converter, switched inductor, voltage multiplier cell
This paper proposes a high step-up high-efficiency converter, comprised of an active switched coupled-inductor cell. The secondary windings are integrated into a rectifier voltage multiplier cell in a boost-flyback configuration, allowing the operation with high voltage gain with low switches duty cycle and low turn-ratios on the coupled-inductors. Both coupled-inductors are integrated into a single core due to the parallel operation of the switches. The leakage inductances of the coupled-inductors are used to mitigate the reverse recovery currents of the diodes, while regenerative clamp circuits are used to protect the switches from the voltage spikes caused by the leakage inductances. The operation of the converter is analyzed both quantitatively and qualitatively, and the achieved results are validated through experimentation of a 400 W prototype. A 97.1% CEC efficiency is also reported.
Science Mapping: A Scientometric Review on Resource Curses, Dutch Diseases, and Conflict Resources during 1993−2020
Chi-Swian Wong
March 28, 2023 (v1)
Keywords: African countries, bibliometric analysis, CiteSpace, Conflict Resources, Dutch Diseases, Resource Curses
Over the past few decades, the wealth of Africa has not made African wealthy. There is a voicing that Africa is cursed, whether richly poor or poorly rich. Sub-Saharan Africa is commonplace for political turbulence, as well as humanitarian and economic misery. In such a catastrophic situa-tion, political economics studies have focused on the Resource Curses, Dutch Diseases, and Con-flict Resources in this area. A systematic scientometric analysis of this field would be beneficial but is currently lacking in the academic literature. Using VOSviewer and CiteSpace, this review fills the void by analyzing the 1783 articles published in the WoS SSCI Collection between 1993 and 2020 on the “Resource Curses”, “Dutch Diseases”, and “Conflict Resources”. The author dis-cusses recent papers with disruptive potential, references with the most robust citation explora-tions, and cooperation networks between authors and institutes. Three hotspots were detected: the causes and effects of the Resource... [more]
On the Correlation of Solar Activity and Troposphere on the GNSS/EGNOS Integrity. Fuzzy Logic Approach
Karolina Krzykowska-Piotrowska, Ewa Dudek, Paweł Wielgosz, Beata Milanowska, Jordi Mongay Batalla
March 28, 2023 (v1)
Keywords: GNSS, integrity, satellite navigation signal, solar activity
There is a noticeable number of studies carried out on both the operational parameters of Global Navigation Satellite System (GNSS) and the satellite signal itself. Researchers look for, inter alia, proven sources of errors affecting the integrity of the satellite signal because this parameter determines the approval of the system’s operational use. It also seems of key importance that the atmospheric conditions, in any area of satellite signal usage, should not be underestimated due to their extensive impact. As the ionospheric refraction seriously limits the operational use of the satellite navigation signal, in this article, the authors attempted to quantify the effect of solar activity (expressed by sunspots) on the signal integrity using fuzzy logic. Fuzzy reasoning is used when information is inaccurate or incomplete and necessitates making decisions under conditions of uncertainty. Thanks to fuzzy sets, there are no obstacles to characterize the degree of intensity of a given ph... [more]
Safe Operation Conditions of Electrical Power System Considering Power Balanceability among Power Generators, Loads, and Storage Devices
Saher Javaid, Mineo Kaneko, Yasuo Tan
March 28, 2023 (v1)
Keywords: energy storage devices, power balanceability, power fluctuations, renewable resources
The introduction of an energy storage system plays a vital role in the integration of renewable energy by keeping a stable operation and enhancing the flexibility of the power flow system, especially for an islanding microgrid which is not tied to a grid and for a self-contained microgrid which tries to stay independent from a grid as much as possible. To accommodate the effects of power fluctuations of distributed energy resources and power loads on power systems, a power flow assignment under power balance constraint is essential. However, due to power limitations of power devices, the capacity of storage devices, and power flow connections, the power balance may not be achieved. In this paper, we proposed a system characterization which describes the relation among power generators, power loads, power storage devices, and connections that must be satisfied for a system to operate by keeping SOC limitations of power storage devices. When we consider one power generator, one power loa... [more]
High-Efficient Brushless Wound Rotor Synchronous Machine Topology Based on Sub-Harmonic Field-Excitation Technique
Syed Sabir Hussain Bukhari, Qasim Ali, Jesús Doval-Gandoy, Jong-Suk Ro
March 28, 2023 (v1)
Keywords: brushless operation, sub-harmonic field excitation, synchronous motor
This paper presents a new high-efficient three-phase brushless wound rotor synchronous machine (BL-WRSM) based on a sub-harmonic field excitation technique. In the proposed machine topology, the stator is equipped with two different three-phase windings: (1) main armature winding, and (2) additional armature winding. The main armature winding is based on a 4-pole winding configuration, whereas the additional armature winding is based on a 2-pole winding configuration. Both windings are supplied current from two different inverters, i.e., inverter-1, inverter-2, and simultaneously. Inverter-1 provides the regular input current to the main armature winding, whereas inverter-2 provides a three-phase current of low magnitude to the 2-pole additional armature winding. This generates an additional sub-harmonic component of MMF in the airgap beside the fundamental MMF. On the other side, the rotor is equipped with (1) harmonic, and (2) field windings. These windings are electrically coupled v... [more]
Numerical Analysis on the Flue Gas Temperature Maintenance System of a Solid Fuel-Fired Boiler Operating at Minimum Loads
Michalina Kurkus-Gruszecka, Piotr Krawczyk, Janusz Lewandowski
March 28, 2023 (v1)
Keywords: flue gas bypass, flue gas mixing, flue gas temperature before SCR, low-load power boiler operation, power plant flexibility
Currently, energy policy is associated with the increase in the share of renewable sources in systemic energy production. Due to this trend, coal-fired power units must increase their work flexibility. Adapting a coal power plant to work with a lower load often causes the issue of maintaining the temperature before the selective catalytic reduction (SCR) installation at a sufficiently high level. This paper presents a CFD analysis of the mixing area of two flue gas streams before the SCR installation with various methods for mixing flue gas streams. The novelty of the work is mixing the flue gas streams of different temperatures using a flap shape developed by the authors. A series of numerical simulations were performed to develop the location and method of introducing the higher temperature gas, obtaining a uniform distribution of the exhaust gas temperature. The simulation scheme was applied to a series of geometrical modifications of the boundary conditions. The tested solution usi... [more]
Preliminary Analysis of an Aged RPV Subjected to Station Blackout
Rosa Lo Frano, Salvatore Angelo Cancemi, Piotr Darnowski, Riccardo Ciolini, Sandro Paci
March 28, 2023 (v1)
Keywords: ageing, creep, finite element, long-term operation, MELCOR, reactor pressure vessel, station blackout
Today, 46% of operating Nuclear Power Plants (NPP) have a lifetime between 31 and 40 years, while 19% have been in operation for more than 40 years. Long Term Operation (LTO) is an urgent requirement for all of the nuclear industry. The aim of this study is to assess the performance of a reactor pressure vessel (RPV) subjected to a station blackout (SBO) event. Alterations suffered by the material properties and creep at elevated temperatures are considered. In this study, coupling between MELCOR and Finite Element Method (FEM) codes is carried out. In the Finite Element (FE) model, the combined effects of ageing and creep are implemented through degraded material properties and a viscoplastic model. The reliability of the model is validated by comparing the FOREVER/C1 experimental results. The results show that the RPV lower head bends downwards with a maximum radial expansion of about 260 mm and RPV thermomechanical properties are reduced by more than 50% at high temperatures. The ef... [more]
A Method for Grading the Hidden Dangers of Urban Gas Polyethylene Pipelines Based on Improved PLC Methods
Yunlong Wang, Zhiting Liu, Xinru Huang, Haizhou Lv, Yun Wu, Kai Zhou
March 28, 2023 (v1)
Keywords: compensation coefficient, failure database of pipelines, hidden dangers classification, polyethylene, urban gas pipelines
The classification of hidden dangers in urban gas pipelines plays a vital role in the smooth operation of urban gas pipelines and in solving the problem of hidden safety dangers in urban gas pipelines. In recent years, the number and proportion of polyethylene (PE) pipelines in urban gas pipelines are increasing day by day, but the current classification of hidden dangers in urban gas pipelines is still based on steel pipelines, and the classification method is highly subjective. Therefore, this paper proposes an improved PLC method that integrates the use of a risk matrix and compensation coefficient to solve the problem of grading the hidden dangers of PE pipelines of urban gas. The improved PLC method is based on the failure database of urban gas PE pipelines to obtain the vulnerability and severity of consequences when determining the initial level of hidden dangers, and the compensation coefficient is modified according to regional vulnerability, ease of rectification, condition a... [more]
Measurement of Forces in a Mining Plough Chain during Operation
Mariusz Szot, Łukasz Herezy, Piotr Szade, Witold Frąc
March 28, 2023 (v1)
Keywords: cylindrical strain gauges, force measurement, mining plough chain, on-site measurements
Pulling chains are one of the most critical components of a plough longwall system. Their failure is hard to predict and results in costly and lengthy downtimes. Measurements of the actual forces acting on a plough chain are needed as they can provide important information about the nature of their operation and contribute to preventing their wear and failure by supplementing data gathered by a plough control station. In this work, a strain gauge system for the measurement of the forces in a plough chain is designed, manufactured and tested under real conditions for the first time. Constructed using a cylindrical strain gauge and widely available electronic components, the finished sensor was calibrated on a testing machine and used to measure forces in a 42 × 137 plough chain at LW Bogdanka. Measurements conducted under real conditions show that forces in the chain during steady ploughing does not exceed 400 kN. However, the forces peaked to up to 728.6 kN at certain points in the ope... [more]
Impact of Time Resolution on Curtailment Losses in Hybrid Wind-Solar PV Plants
Antun Meglic, Ranko Goic
March 28, 2023 (v1)
Keywords: curtailment losses, hybrid power plants, smoothing effect, solar power, time resolution, wind power
Curtailment losses for large-scale hybrid wind−solar photovoltaic (PV) plants with a single grid connection point are often calculated in 1 h time resolution, underestimating the actual curtailment losses due to the flattening of power peaks occurring in shorter time frames. This paper analyses the curtailment losses in hybrid wind−PV plants by utilising different time resolutions of wind and PV production while varying the grid cut-off power, wind/solar PV farm sizes, and shares of wind/PV capacity. Highly resolved 1 s measurements from the operational wind farm and pyranometer are used as an input to specialized wind and PV farm power production models that consider the smoothing effect. The results show that 15 min resolution is preferred over 1 h resolution for large-scale hybrid wind−PV plants if more accurate assessment of curtailment losses is required. Although 1 min resolution additionally increases the estimation accuracy over 15 min resolution, the improvement is not signifi... [more]
Increasing Drilling Speed by Absorption and Hydraulic Supercharging of Drill String in Formation Containing Hydrogen Sulfide: A Case Study
Yongwang Liu, Xiaoyuan Chen, Yixiang Niu, Zhichuan Guan, Wei Wang, Chuanfu Liu
March 28, 2023 (v1)
Keywords: downhole speed-up tools, hydrogen sulfide, the speed-up technology by drill string absorption and hydraulic supercharging, well WWY 1
Increasing drilling speed and shortening the well construction period are the goals of the drilling field. The use of downhole speed-up tools has been noted for its advantages such as no additional cost, no change in drilling equipment and no impact on normal drilling operations. However, conventional downhole speed-up tools cannot meet the needs when the drilled formation contains hydrogen sulfide. Then, the technology test on increasing drilling speed by absorption and hydraulic supercharging of drill string in hydrogen sulfide formation was carried out in well Wanweiye1 (WWY1), Anhui Province, China. The results show that: firstly, the speed-up device by absorption and hydraulic supercharging of drill string can be used in the formation containing hydrogen sulfide, and can still perform normal drilling operations with a hydrogen sulfide concentration of 567 ppm; secondly, the speed-up technology by absorption and hydraulic supercharging of drill string has a significant speed-raisin... [more]
Analysis of a Series‑Parallel Resonant Converter for DC Microgrid Applications
Bor-Ren Lin
March 28, 2023 (v1)
Keywords: DC microgrid, series‑parallel resonant converter, zero-voltage switching
An input-series output-parallel soft switching resonant circuit with balance input voltage and primary-side current is studied and implemented for direct current (DC) microgrid system applications. Two resonant circuits are connected with input-series and output-parallel structure to have the advantages of low voltage stresses on active devices and low current stresses on power diodes. A balance capacitor is adopted on high voltage side to balance two input capacitor voltages. The LLC (inductor−inductor−capacitor) resonant circuit cells are employed in the converter to have soft switching operation for power semiconductors. The magnetic coupling component is adopted on the primary-side to automatically realize current balance of the two resonant circuits. In the end, a laboratory hardware circuit is built and tested. Experiments demonstrate and prove the validity of the resonant converter.
Process Improvements for Direct Reduced Iron Melting in the Electric Arc Furnace with Emphasis on Slag Operation
Marcus Kirschen, Thomas Hay, Thomas Echterhof
March 28, 2023 (v1)
Keywords: direct reduced iron, electric arc furnace, process improvement, process model
Steelmaking based on direct reduced iron (DRI, and its compacted derivative hot briquetted iron, HBI) is an anticipated important global alternative to current steel production based on FeOx reduction in blast furnaces due to its lower specific CO2 emission. The majority of DRI is melted and refined in the electric arc furnace with different process conditions compared to the melting of steel scrap due to its raw material composition being rather different. We provide data and analysis of slag composition of DRI charges vs. steel scrap charges for 16 industrial electric arc furnaces (EAFs). Suggestions for optimized slag operation and resulting process improvements of DRI melting in the EAF are given. A dynamic mass and energy model of the DRI melting in the EAF is introduced to illustrate the implications of the adapted slag operation on the EAF process with DRI charges.
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