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Showing records 133 to 157 of 241. [First] Page: 1 3 4 5 6 7 8 9 10 11 Last
A Fault-Tolerant Location Approach for Transient Voltage Disturbance Source Based on Information Fusion
Guoqing Weng, Feiteng Huang, Jun Yan, Xiaodong Yang, Youbing Zhang, Haibo He
February 27, 2019 (v1)
Keywords: automatic location, DG integration, direction-judgment, fault tolerance, information fusion, transient voltage disturbance source
This paper proposed a fault-tolerant approach based on information fusion (IF) to automatically locate the transient voltage disturbance source (TVDS) in smart distribution grids. We first defined three credibility factors that will influence the reliability of the direction-judgments at each power quality monitor (PQM). Then we proposed two rules of influence and a verification factor for the distributed generation (DG) integration. Based on the two sets of direction-judgment criteria, a novel decision-making method with fault tolerance based on the IF theory is proposed for automatic location of the TVDS. Three critical schemes, including credibility fusion, conflict weakening, and correction for DG integration, have been integrated in the proposed fusion method, followed by a reliability evaluation of the location results. The proposed approach was validated on the IEEE 13-node test feeder, and the TVDS location results demonstrated the effectiveness and fault tolerance of the IF ba... [more]
Analyzing Crude Oil Spot Price Dynamics versus Long Term Future Prices: A Wavelet Analysis Approach
Josué M. Polanco-Martínez, Luis M. Abadie
February 27, 2019 (v1)
Keywords: futures oil markets, Maximal Overlap Discrete Wavelet Transform (MODWT), nonlinear causality test, oil spot prices, stochastic model, tight oil, time series analysis, wavelet correlation
The West Texas Intermediate (WTI) spot price shows high volatility and in 2014 and 2015 when quoted prices declined sharply, long-term prices in future markets were less volatile. These prices are different and diverge depending on how they process fundamental and transitory factors. US tight oil production has been a major innovation with significant macroeconomic effects. In this paper we use WTI spot prices and long-term futures prices, the latter calculated as the expected value with a stochastic model calibrated with the futures quotes of each sample day. These long-term prices are the long-term equilibrium value under risk neutral measurement. In order to analyze potential time-scale relationships between spots and future, we perform a wavelet cross-correlation analysis using a novel wavelet graphical tool recently proposed. To check the direction of the causality, we apply non-linear causality tests to raw data and log returns as well as to the wavelet transform of the spot and... [more]
Mechanical Properties of Longmaxi Black Organic-Rich Shale Samples from South China under Uniaxial and Triaxial Compression States
Yusong Wu, Xiao Li, Jianming He, Bo Zheng
February 27, 2019 (v1)
Subject: Materials
Keywords: anisotropy, bedding, confining pressure, hydraulic fracturing, rock mechanics, shale
With the exploitation of shale gas booming all over the world, more and more studies are focused on the core technology, hydraulic fracturing, to improve commercial exploitation. Shale gas resources in China are enormous. In this research, a series of tests were carried out with samples of black organic-rich shale from the Lower Silurian Longmaxi formation, south China. Samples were drilled from different directions and were subjected to uniaxial and triaxial condition with various confining pressures, aiming at studying its rock mechanics properties, so as to provide basis for research and breakthrough of hydraulic fracturing technology. According to the results of the study, the development and distribution of shale’s bedding planes significantly impact its mechanical properties. Shale samples show obvious brittle characteristics under low confining pressure, and its mechanical behavior begins to transform from brittle to plastic characteristics with increasing confining pressure. Sh... [more]
Performance of a Predictive Model for Calculating Ascent Time to a Target Temperature
Jin Woo Moon, Min Hee Chung, Hayub Song, Se-Young Lee
February 27, 2019 (v1)
Keywords: artificial neural network (ANN), ascending time, heating system, predictive controls, setback temperature
The aim of this study was to develop an artificial neural network (ANN) prediction model for controlling building heating systems. This model was used to calculate the ascent time of indoor temperature from the setback period (when a building was not occupied) to a target setpoint temperature (when a building was occupied). The calculated ascent time was applied to determine the proper moment to start increasing the temperature from the setback temperature to reach the target temperature at an appropriate time. Three major steps were conducted: (1) model development; (2) model optimization; and (3) performance evaluation. Two software programs—Matrix Laboratory (MATLAB) and Transient Systems Simulation (TRNSYS)—were used for model development, performance tests, and numerical simulation methods. Correlation analysis between input variables and the output variable of the ANN model revealed that two input variables (current indoor air temperature and temperature difference from the targe... [more]
Systematic Assessment of Carbon Emissions from Renewable Energy Access to Improve Rural Livelihoods
Judith A. Cherni, Raúl Olalde Font, Lucía Serrano, Felipe Henao, Antonio Urbina
February 27, 2019 (v1)
Subject: Energy Policy
Keywords: life-cycle analysis (LCA), multi-criteria decision analysis (MCDA), photovoltaic technologies, rural energy and development, SURE-DSS
One way of increasing access to electricity for impoverished unconnected areas without adding significant amounts of CO₂ to the atmosphere is by promoting renewable energy technologies. However, decision-makers rarely, if ever, take into account the level of in-built energy requirements and consequential CO₂ emissions found in renewable energy, particularly photovoltaic cells and related equipment, which have been widely disseminated in developing countries. The deployment of solar panels worldwide has mostly relied on silicon crystalline cell modules, despite the fact that less polluting material—in particular, thin film and organic cells—offers comparatively distinct technical, environmental and cost advantages characteristics. A major scientific challenge has thus been the design of a single decision-making approach to assess local and global climate change-related impacts as well as the socio-economic effects of low-carbon technology. The article focuses on the functions of the mul... [more]
Wireless Power Transfer System Architectures for Portable or Implantable Applications
Yan Lu, Dongsheng Brian Ma
February 27, 2019 (v1)
Keywords: coupling coils, DC-DC converter, inductive power transfer, low-dropout regulator, power amplifier, rectifier, voltage regulation, wireless power transfer
This paper discusses the near-field inductive coupling wireless power transfer (WPT) at the system level, with detailed analyses on each state-of-the-art WPT output voltage regulation topologies. For device miniaturization and power loss reduction, several novel architectures for efficient WPT were proposed in recent years to reduce the number of passive components as well as to improve the system efficiency or flexibility. These schemes are systematically studied and discussed in this paper. The main contribution of this paper is to provide design guidelines for WPT system design. In addition, possible combinations of the WPT building block configurations are summarized, compared, and investigated for potential new architectures.
Research on a Micro-Grid Frequency Modulation Strategy Based on Optimal Utilization of Air Conditioners
Qingzhu Wan, Yuan Bian, Yalan Chen
February 27, 2019 (v1)
Keywords: energy storage system, frequency control, micro-grid, thermostatically controlled loads
With the proportion of air conditioners increasing gradually, they can provide a certain amount of frequency-controlled reserves for a micro-grid. Optimizing utilization of air conditioners and considering load response characteristics and customer comfort, the frequency adjustment model is a quadratic function model between the trigger temperature of the air conditioner compressor, and frequency variation is provided, which can be used to regulate the trigger temperature of the air conditioner when the micro-grid frequency rises and falls. This frequency adjustment model combines a primary frequency modulation method and a secondary frequency modulation method of the energy storage system, in order to optimize the frequency of a micro-grid. The simulation results show that the frequency modulation strategy for air conditioners can effectively improve the frequency modulation ability of air conditioners and frequency modulation effects of a micro-grid in coordination with an energy sto... [more]
Modeling of a Field-Modulated Permanent-Magnet Machine
Xianglin Li, K. T. Chau, Yubin Wang
February 27, 2019 (v1)
Keywords: d-q frame, field-modulated permanent magnet (FMPM) machine, finite element analysis (FEA), Modelling
In this work, an effective field-modulated permanent-magnet (FMPM) machine was investigated, in which the spoke-magnet outer rotor and open-slot stator were employed. The objective of this paper is to provide the mathematical modeling analysis that was performed for the purpose of control research on this type of FMPM machine. The simulation results by means of finite element analysis (FEA) are given to verify the theoretical analysis and the validity of mathematical model. A prototype machine was also fabricated for experimentation. Both the analytical model and the FEA results are validated by experimental tests on the prototype machine.
Sensorless Control of Interior Permanent Magnet Synchronous Motor in Low-Speed Region Using Novel Adaptive Filter
Lisi Tian, Jin Zhao, Jiajiang Sun
February 27, 2019 (v1)
Keywords: adaptive filter, interior permanent magnet synchronous motor (IPMSM), sensorless control, speed estimation
This paper presents a novel position and speed estimation method for low-speed sensorless control of interior permanent-magnet synchronous machines (IPMSMs). The parameter design of the position and speed estimator is based on the sampled current rather than the motor electrical parameters. The proposed method not only simplifies the parameter design, it enables the estimator to work normally even in the condition that the electrical parameters are uncertain or varied. The adaptive filters are adopted to extract the desired high frequency current. The structure and corresponding transfer function are analyzed. To address the shortage of insufficient stop-band attenuation, the structure of the adaptive filter is modified to provide suitable bandwidth and stop-band attenuation simultaneously. The effectiveness of the proposed sensorless control strategy has been verified by simulations and experiments.
Artificial Neural Network Model for Alkali-Surfactant-Polymer Flooding in Viscous Oil Reservoirs: Generation and Application
Si Le Van, Bo Hyun Chon
February 27, 2019 (v1)
Keywords: artificial neural network, chemical flooding, enhanced oil recovery, net present value, Optimization
Chemical flooding has been widely utilized to recover a large portion of the oil remaining in light and viscous oil reservoirs after the primary and secondary production processes. As core-flood tests and reservoir simulations take time to accurately estimate the recovery performances as well as analyzing the feasibility of an injection project, it is necessary to find a powerful tool to quickly predict the results with a level of acceptable accuracy. An approach involving the use of an artificial neural network to generate a representative model for estimating the alkali-surfactant-polymer flooding performance and evaluating the economic feasibility of viscous oil reservoirs from simulation is proposed in this study. A typical chemical flooding project was referenced for this numerical study. A number of simulations have been made for training on the basis of a base case from the design of 13 parameters. After training, the network scheme generated from a ratio data set of 50%-20%-30%... [more]
Moisture Migration in an Oil-Paper Insulation System in Relation to Online Partial Discharge Monitoring of Power Transformers
Wojciech Sikorski, Krzysztof Walczak, Piotr Przybylek
February 27, 2019 (v1)
Keywords: oil-paper insulation, online monitoring, partial discharge (PD), power transformer, water migration
Most power transformers operating in a power system possess oil-paper insulation. A serious defect of this type of insulation, which is associated with long operation time, is an increase in the moisture content. Moisture introduces a number of threats to proper operation of the transformer, e.g., ignition of partial discharges (PDs). Due to the varying temperature of the insulation system during the unit’s normal operation, a dynamic change (migration of water) takes place, precipitating the oil-paper system from a state of hydrodynamic equilibrium. This causes the PDs to be variable in time, and they may intensify or extinguish. Studies on model objects have been conducted to determine the conditions (temperature, humidity, time) that will have an impact on the ignition and intensity of the observed phenomenon of PDs. The conclusions of this study will have a practical application in the evaluation of measurements conducted in the field, especially in relation to the registration of... [more]
Numerical Models for Viscoelastic Liquid Atomization Spray
Lijuan Qian, Jianzhong Lin, Fubing Bao
February 27, 2019 (v1)
Keywords: atomization spray, numerical modeling, viscoelastic fluid
Atomization spray of non-Newtonian liquid plays a pivotal role in various engineering applications, especially for the energy utilization. To operate spray systems efficiently and well understand the effects of liquid rheological properties on the whole spray process, a comprehensive model using Euler-Lagrangian approaches was established to simulate the evolution of the atomization spray for viscoelastic liquid. Based on the Oldroyd model, the viscoelastic linear dispersion relation was introduced into the primary atomization; an extended viscoelastic version of Taylor analogy breakup (TAB) model was proposed; and the coalescence criteria was modified by rheological parameters, such as the relaxation time, the retardation time and the zero shear viscosity. The predicted results are validated with experimental data varying air-liquid mass flow ratio (ALR). Then, numerical calculations are conducted to investigate the characteristics of viscoelastic liquid atomization process. Results s... [more]
Production of Synthetic Natural Gas from Refuse-Derived Fuel Gasification for Use in a Polygeneration District Heating and Cooling System
Natalia Kabalina, Mário Costa, Weihong Yang, Andrew Martin
February 27, 2019 (v1)
Keywords: district heating and cooling systems, gasification, Polygeneration, refuse derived fuels, synthetic natural gas
Nowadays conventional district heating and cooling (DHC) systems face the challenge of reducing fossil fuel dependency while maintaining profitability. To address these issues, this study examines the possibility of retrofitting DHC systems with refuse-derived fuel (RDF) gasifiers and gas upgrading equipment. A novel system is proposed based on the modification of an existing DHC system. Thermodynamic and economic models were established to allow for a parametric analysis of key parameters. The study revealed that such an upgrade is both feasible and economically viable. In the basic scenario, the retrofitted DHC system can simultaneously produce 60.3 GWh/year of heat, 65.1 GWh/year of cold, 33.2 GWh/year of electricity and 789.5 tons/year of synthetic natural gas. A significant part of the heat load can be generated from the waste heat of the upgrading equipment. The investment in retrofitting the polygeneration DHC system presents a payback period of 3 years.
Design of an Energy Efficient Future Base Station with Large-Scale Antenna System
Byung Moo Lee, Youngok Kim
February 27, 2019 (v1)
Keywords: base station (BS), energy efficiency (EE), large-scale (LS) antenna system
Due to the continuous increase in data demanded by end-users, an energy-efficient base station (BS) is a vital topic of interest that would not only result in a substantial economic impact on service providers, but would also reduce the carbon footprint of operating a network. In this regard, we propose the structure and systematic operation of a BS with a large-scale (LS) antenna system that can increase the energy efficiency (EE) of cellular systems. The proposed BS structure includes various power-related units, such as a central management apparatus, power controller, EE calculator, radio site-dependent parameter space (RSD-PS) and determiner. With the information provided from each unit, the decision unit determines how to adjust each component of the BS in order to maximize the EE. Extensive simulations show that the proposed BS improves the EE performance by about 83.05% relative to the reference BS.
Laboratory Experiment and Numerical Analysis of a New Type of Solar Tower Efficiently Generating a Thermal Updraft
Yuji Ohya, Masaki Wataka, Koichi Watanabe, Takanori Uchida
February 27, 2019 (v1)
Keywords: computational fluid dynamics (CFD), diffuser, laboratory experiment, solar tower, thermal updraft
A new type of solar tower was developed through laboratory experiments and numerical analyses. The solar tower mainly consists of three components. The transparent collector area is an aboveground glass roof, with increasing height toward the center. Attached to the center of the inside of the collector is a vertical tower within which a wind turbine is mounted at the lower entry to the tower. When solar radiation heats the ground through the glass roof, ascending warm air is guided to the center and into the tower. A solar tower that can generate electricity using a simple structure that enables easy and less costly maintenance has considerable advantages. However, conversion efficiency from sunshine energy to mechanical turbine energy is very low. Aiming to improve this efficiency, the research project developed a diffuser-type tower instead of a cylindrical tower, and investigated a suitable diffuser shape for practical use. After changing the tower height and diffuser open angle, w... [more]
Evaluation of Conservation Voltage Reduction with Analytic Hierarchy Process: A Decision Support Framework in Grid Operations Planning
Kyungsung An, Hao Jan Liu, Hao Zhu, Zhao Yang Dong, Kyeon Hur
February 27, 2019 (v1)
Keywords: analytic hierarchy process (AHP), conservation voltage reduction (CVR), CVR factor, integer programming, power transfer distribution factor (PTDF), voltage sensitivity factor (VSF)
This paper presents a systematic framework to evaluate the performance of conservation voltage reduction (CVR) by determining suitable substations for CVR in operations planning. Existing CVR planning practice generally only focuses on the energy saving aspect without taking other underlying attributes into account, i.e., network topology and reduced voltage effects on other substations. To secure the desired operating reserve and avoid any adverse impacts, these attributes should be considered for implementing CVR more effectively. This research develops a practical decision-making framework based on the analytic hierarchy process (AHP) to quantify several of the aforementioned attributes. Candidate substations for CVR deployment are prioritized such that performances are compared in terms of power transfer distribution factor (PTDF), voltage sensitivity factor (VSF), and CVR factor. In addition, to meet a specified reserve requirement, an integer programming approach is adopted to se... [more]
Electrodeposited Magnesium Nanoparticles Linking Particle Size to Activation Energy
Chaoqi Shen, Kondo-Francois Aguey-Zinsou
February 27, 2019 (v1)
Keywords: activation energy, hydrogen storage, magnesium, nanosize, particle size
The kinetics of hydrogen absorption/desorption can be improved by decreasing particle size down to a few nanometres. However, the associated evolution of activation energy remains unclear. In an attempt to clarify such an evolution with respect to particle size, we electrochemically deposited Mg nanoparticles on a catalytic nickel and noncatalytic titanium substrate. At a short deposition time of 1 h, magnesium particles with a size of 68 ± 11 nm could be formed on the nickel substrate, whereas longer deposition times led to much larger particles of 421 ± 70 nm. Evaluation of the hydrogen desorption properties of the deposited magnesium nanoparticles confirmed the effectiveness of the nickel substrate in facilitating the recombination of hydrogen, but also a significant decrease in activation energy from 56.1 to 37.8 kJ·mol−1 H₂ as particle size decreased from 421 ± 70 to 68 ± 11 nm. Hence, the activation energy was found to be intrinsically linked to magnesium particle size. Such a re... [more]
Numerical Simulation of a Vortex Combustor Based on Aluminum and Steam
Xianhe Chen, Zhixun Xia, Liya Huang, Likun Ma
February 27, 2019 (v1)
Keywords: aluminum particle, diffusion flame, numerical simulation, steam, vortex combustor
In this paper we report a new development in the numerical model for aluminum-steam combustion. This model is based on the diffusion flame of the continuum regime and the thermal equilibrium between the particle and the flow field, which can be used to calculate the aluminum particle combustion model for two phase calculation conditions. The model prediction is in agreement with the experimental data. A new type of vortex combustor is proposed to increase the efficiency of the combustion of aluminum and steam, and the mathematical model of the two phase reacting flow in this combustor is established. The turbulence effects are modeled using the Reynolds Stress Model (RSM) with Linear Pressure-Strain approach, and the Eddy-Dissipation model is used to simulate the gas phase combustion. Aluminum particles are injected into the vortex combustor, forming a swirling flow around the chamber, whose trajectories are traced using the Discrete Phase Model (DPM). The simulation results show that... [more]
Application of Project Management Process on Environmental Management System Improvement in Mining-Energy Complexes
Jelena Malenović Nikolić, Dejan Vasović, Ivana Filipović, Stevan Mušicki, Ivica Ristović
February 27, 2019 (v1)
Subject: Energy Policy
Keywords: environment, management, mining and energy complexes, network planning, sustainable development
Aims and background: Mining and energy complexes in Serbia are recognized as a major source of a large number of pollutants. Serbia’s environmental performance reports clearly indicate that large mining and energy complexes are the dominant source of air pollution. It is difficult to determine which of them remarkably threaten the quality of the environment, as all the basic elements of the environment (air, water, and soil) are threatened, not just one. Mining and energy complexes significantly reduce the quality of the immediate environment, as the distance areas throughout water and air pollution propagation. Additional motivation for this study lies in the fact that large mining and energy complexes are particularly interesting because they are located in the immediate vicinity or large rivers (mostly the Danube), which are protected in many national and international legislation acts (particularly the Danube). The basis for the preservation of environmental quality is an effective... [more]
A Decentralized Control Method for Distributed Generations in an Islanded DC Microgrid Considering Voltage Drop Compensation and Durable State of Charge
Chul-Sang Hwang, Eung-Sang Kim, Yun-Su Kim
February 27, 2019 (v1)
Keywords: decentralized control, durable state of charge (SOC), islanded DC microgrid, voltage drop compensation
This paper presents a decentralized control method for distributed generations (DGs) in an islanded direct current (DC) microgrid. In most typical DC microgrids, a decentralized control method is based on a voltage droop control method. However, the grid voltage differs from node to node due to line voltage drop, and hence the power sharing ratio among DGs cannot be matched with as desired value. Especially in an islanded DC microgrid including an energy storage system as a voltage source, it is difficult for DGs to maintain the charge state of the ESS in a decentralized way. To overcome this problem, state of charge (SOC)-voltage droop control is applied to the ESS. By using the proposed droop method, the SOC information can be assigned to the grid voltage, and hence the other DGs are able to support the SOC in a decentralized way. For DGs to enhance the accuracy of the SOC estimation, voltage drop is compensated for based on forecasting data and line impedance data. The simulation is... [more]
Portfolio Decision of Short-Term Electricity Forecasted Prices through Stochastic Programming
Agustín A. Sánchez de la Nieta, Virginia González, Javier Contreras
February 27, 2019 (v1)
Keywords: ARIMA models, day-ahead electricity market price, forecasting portfolio, stochastic programming
Deregulated electricity markets encourage firms to compete, making the development of renewable energy easier. An ordinary parameter of electricity markets is the electricity market price, mainly the day-ahead electricity market price. This paper describes a new approach to forecast day-ahead electricity market prices, whose methodology is divided into two parts as: (i) forecasting of the electricity price through autoregressive integrated moving average (ARIMA) models; and (ii) construction of a portfolio of ARIMA models per hour using stochastic programming. A stochastic programming model is used to forecast, allowing many input data, where filtering is needed. A case study to evaluate forecasts for the next 24 h and the portfolio generated by way of stochastic programming are presented for a specific day-ahead electricity market. The case study spans four weeks of each one of the years 2014, 2015 and 2016 using a specific pre-treatment of input data of the stochastic programming (SP... [more]
HVDC-System-Interaction Assessment through Line-Flow Change-Distribution Factor and Transient-Stability Analysis at Planning Stage
Sungchul Hwang, Jaegul Lee, Gilsoo Jang
February 27, 2019 (v1)
Subject: Other
Keywords: high-voltage direct current (HVDC), interaction, Planning, transient stability
Many of the recent projects for new transmission line have considered the high-voltage direct current (HVDC) system, owing to the many advantages of the direct current (DC) system. The most noteworthy advantage is that a cable can serve as a substitute for the overhead transmission line in residential areas; therefore, the HVDC system application is increasing, and as the number of DC systems in the power system increases, the interaction assessment regarding the HVDC system gains importance. An index named multi-infeed interaction factor (MIIF) is commonly used to estimate the interaction between power converters; however, the HVDC system is composed of two converters and a transmission line. The MIIF represents the interaction between the rectifiers and inverters, but not for the whole system. In this work, a method to assess the interaction of the whole system was therefore studied. To decide on the location of the new HVDC transmission system at the planning stage, in consideration... [more]
Decoupling Design and Verification of a Free-Piston Linear Generator
Peng Sun, Chi Zhang, Jinhua Chen, Fei Zhao, Youyong Liao, Guilin Yang, Chinyin Chen
February 27, 2019 (v1)
Keywords: decoupling design, free-piston, linear generator, power and efficiency distribution
This paper proposes a decoupling design approach for a free-piston linear generator (FPLG) constituted of three key components, including a combustion chamber, a linear generator and a gas spring serving as rebounding device. The approach is based on the distribution of the system power and efficiency, which provides a theoretical design method from the viewpoint of the overall power and efficiency demands. The energy flow and conversion processes of the FPLG are analyzed, and the power and efficiency demands of the thermal-mechanical and mechanical-electrical energy conversion are confirmed. The energy and efficiency distributions of the expansion and compression strokes within a single stable operation cycle are analyzed and determined. Detailed design methodologies of crucial geometric dimensions and operational parameters of each key component are described. The feasibility of the proposed decoupling design approach is validated through several design examples with different output... [more]
Green Small Cell Operation of Ultra-Dense Networks Using Device Assistance
Gilsoo Lee, Hongseok Kim
February 27, 2019 (v1)
Keywords: belief propagation, cellular networks, Energy Efficiency, Optimization, small cell
As higher performance is demanded in 5G networks, energy consumption in wireless networks increases along with the advances of various technologies, so enhancing energy efficiency also becomes an important goal to implement 5G wireless networks. In this paper, we study the energy efficiency maximization problem focused on finding a suitable set of turned-on small cell access points (APs). Finding the suitable on/off states of APs is challenging since the APs can be deployed by users while centralized network planning is not always possible. Therefore, when APs in small cells are randomly deployed and thus redundant in many cases, a mechanism of dynamic AP turning-on/off is required. We propose a device-assisted framework that exploits feedback messages from the user equipment (UE). To solve the problem, we apply an optimization method using belief propagation (BP) on a factor graph. Then, we propose a family of online algorithms inspired by BP, called DANCE, that requires low computati... [more]
Fault-Ride through Strategy for Permanent-Magnet Synchronous Generators in Variable-Speed Wind Turbines
Mohamed Abdelrahem, Ralph Kennel
February 27, 2019 (v1)
Keywords: fault-ride through, Model Predictive Control, permanent-magnet synchronous generator, wind turbine
Currently, the electric power production by wind energy conversion systems (WECSs) has increased significantly. Consequently, wind turbine (WT) generators are requested to fulfill the grid code (GC) requirements stated by network operators. In case of grid faults/voltage dips, a mismatch between the generated active power from the wind generator and the active power delivered to the grid is produced. The conventional approach is using a braking chopper (BC) in the DC-link to dissipate this active power. This paper proposes a fault-ride through (FRT) strategy for variable-speed WECSs based on permanent magnet synchronous generators (PMSGs). The proposed strategy exploits the rotor inertia of the WECS (inertia of the WT and PMSG) to store the surplus active power during the grid faults/voltage dips. Thus, no additional hardware components are requested. Furthermore, a direct model predictive control (DMPC) scheme for the PMSG is proposed in order to enhance the dynamic behavior of the WE... [more]
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