Energy concentration on S-300 pulsed power generator

Energy Technology Data Exchange (ETDEWEB)

Bakshaev, Yu Z; Chernenko, A S; Korolev, V D; Mizhiritskij, V I; Zazhivikhin, V V [Kurchatov Institute, Moscow (Russian Federation)

1997-12-31

Energy concentration in fast Z-pinch investigation experiments on an 8-module 10 TW pulsed power S-300 generator (1.3 MV, 45 ns FWHM, 0.15 Ohm) is realized by a 3-d vacuum energy concentrator. The concentrator was constructed on the basis of triplate MITLs connected in parallel at the central unit where the Z-pinch is formed. At some start-up experiments on the 8-module installation version at 700 kV incident wave amplitude on concentrator for a gas puff load current of 4 MA with rise time of about 60 ns was obtained. The efficiency or current transfer from the concentrator input to the load for both a gas liner and a short-circuited case was practically the same. (author). 4 figs., 4 refs.

LOW-POWER AC LOADS AND ELECTRICAL POWER QUALITY

Directory of Open Access Journals (Sweden)

EPURE S.

2016-12-01

Full Text Available This paper deals with experimental study and numerical simulation of single phase AC low power loads: artificial light sources, personal computers, refrigeration units, air conditioning units and TV receivers. These loads are in such large numbers that represents the main source of disturbances (harmonic current, reactive power and unbalanced three-phase network. The obtained simulation models, verified by comparison with experimental results may be used in larger simulation models for testing and sizing the optimum parameters of active power filters. Models can also be used to study the interactions between grid elements and various loads or situations.

Efficient Load Scheduling Method For Power Management

Directory of Open Access Journals (Sweden)

Vijo M Joy

2015-08-01

Full Text Available An efficient load scheduling method to meet varying power supply needs is presented in this paper. At peak load times the power generation system fails due to its instability. Traditionally we use load shedding process. In load shedding process disconnect the unnecessary and extra loads. The proposed method overcomes this problem by scheduling the load based on the requirement. Artificial neural networks are used for this optimal load scheduling process. For generate economic scheduling artificial neural network has been used because generation of power from each source is economically different. In this the total load required is the inputs of this network and the power generation from each source and power losses at the time of transmission are the output of the neural network. Training and programming of the artificial neural networks are done using MATLAB.

Hip orthosis powered by pneumatic artificial muscle: voluntary activation in absence of myoelectrical signal.

Science.gov (United States)

do Nascimento, Breno Gontijo; Vimieiro, Claysson Bruno Santos; Nagem, Danilo Alves Pinto; Pinotti, Marcos

2008-04-01

Powered orthosis is a special class of gait assist device that employs a mechanical or electromechanical actuator to enhance movement of hip, knee, or ankle articulations. Pneumatic artificial muscle (PAM) has been suggested as a pneumatic actuator because its performance is similar to biological muscle. The electromyography (EMG) signal interpretation is the most popular and simplest method to establish the patient voluntary control of the orthosis. However, this technique is not suitable for patients presenting neurological lesions causing absence or very low quality of EMG signal. For those cases, an alternative control strategy should be provided. The aim of the present study is to develop a gait assistance orthosis for lower limb powered by PAMs controlled by a voluntary activation method based on the angular behavior of hip joint. In the present study, an orthosis that has been molded in a patient was employed and, by taking her anthropometric parameters and movement constraints, the adaptation of the existing orthosis to the powered orthosis was planned. A control system was devised allowing voluntary control of a powered orthosis suitable for patients presenting neurological lesions causing absence or very low quality of EMG signal. A pilot clinical study was reported where a patient, victim of poliovirus, successfully tested a hip orthosis especially modified for the gait test evaluation in the parallel bar system. The hip orthosis design and the control circuitry parameters were able to be set to provide satisfactory and comfortable use of the orthosis during the gait cycle.

Impact Study on Power Factor of Electrical Load in Power Distribution System

International Nuclear Information System (INIS)

Syirrazie Che Soh; Harzawardi Hasim; Ahmad Asraf, A.S.

2014-01-01

Low Power Factor of electrical loads cause high current is drawn from power supply. The impact of this circumstance is influenced by impedance of electrical load. Therefore, the key consideration of this study is how impedance of electrical loads influence power factor of electrical loads, and then power distribution as the whole. This study is important to evaluate the right action to mitigate low power factor effectively for electrical energy efficiency purpose. (author)

Voluntary muscle activation improves with power training and is associated with changes in gait speed in mobility-limited older adults

DEFF Research Database (Denmark)

Hvid, Lars G; Strotmeyer, Elsa S; Skjødt, Mathias

2016-01-01

Incomplete voluntary muscle activation may contribute to impaired muscle mechanical function and physical function in older adults. Exercise interventions have been shown to increase voluntary muscle activation, although the evidence is sparse for mobility-limited older adults, particularly...... in association with physical function. This study examined the effects of 12weeks of power training on outcomes of voluntary muscle activation and gait speed in mobility-limited older adults from the Healthy Ageing Network of Competence (HANC) study. We included 37 older men and women with a usual gait speed...... in TG (r=0.67, pactivation is improved in mobility-limited older adults following 12-weeks of progressive power training, and is associated with improved maximal gait speed. Incomplete voluntary muscle activation should be considered one of the key mechanisms...

Financing concentrating solar power in the Middle East and North Africa-Subsidy or investment?

International Nuclear Information System (INIS)

Trieb, Franz; Mueller-Steinhagen, Hans; Kern, Juergen

2011-01-01

The paper presents a strategy for the market introduction of concentrating solar power (CSP) plants in the Middle East and North Africa (MENA) that will not require considerable subsidization and will not constitute a significant burden for electricity consumers in the region. In the first section, the paper explains the need of MENA countries for sustainable supply of electricity and calculates the cost of electricity for a model case country. In the second part, the cost development of concentrating solar power plants is calculated on the basis of expectations for the expansion of CSP on a global level. After that, the challenges for the market introduction of CSP in MENA are explained. Finally, we present a strategy for the market introduction of CSP in MENA, removing the main barriers for financing and starting market introduction in the peak load and the medium load segment of power supply. The paper explains why long-term power purchase agreements (PPA) for CSP should be calculated on the basis of avoided costs, starting in the peak load segment. Such PPA are not yet available, the paper aims to convince policy makers to introduce them. - Research Highlights: → Concentrating Solar Power in the Mediterranean Region (MED-CSP 2005) (www.dlr.de/tt/med-csp). → Trans-Mediterranean Interconnection for Concentrating Solar Power (TRANS-CSP 2006) (www.dlr.de/tt/trans-csp). → Concentrating Solar Power for Seawater Desalination (AQUA-CSP 2007) (www.dlr.de/tt/aqua-csp). → Risk of Energy Availability: Common Corridors for Europe Supply Security (REACCESS 2009) (http://reaccess.epu.ntua.gr/). → Combined Solar Power and Desalination in the Mediterranean (MED-CSD 2010) (www.med-csd-ec.eu).

Concentrating solar thermal power.

Science.gov (United States)

Müller-Steinhagen, Hans

2013-08-13

In addition to wind and photovoltaic power, concentrating solar thermal power (CSP) will make a major contribution to electricity provision from renewable energies. Drawing on almost 30 years of operational experience in the multi-megawatt range, CSP is now a proven technology with a reliable cost and performance record. In conjunction with thermal energy storage, electricity can be provided according to demand. To date, solar thermal power plants with a total capacity of 1.3 GW are in operation worldwide, with an additional 2.3 GW under construction and 31.7 GW in advanced planning stage. Depending on the concentration factors, temperatures up to 1000°C can be reached to produce saturated or superheated steam for steam turbine cycles or compressed hot gas for gas turbine cycles. The heat rejected from these thermodynamic cycles can be used for sea water desalination, process heat and centralized provision of chilled water. While electricity generation from CSP plants is still more expensive than from wind turbines or photovoltaic panels, its independence from fluctuations and daily variation of wind speed and solar radiation provides it with a higher value. To become competitive with mid-load electricity from conventional power plants within the next 10-15 years, mass production of components, increased plant size and planning/operating experience will be accompanied by technological innovations. On 30 October 2009, a number of major industrial companies joined forces to establish the so-called DESERTEC Industry Initiative, which aims at providing by 2050 15 per cent of European electricity from renewable energy sources in North Africa, while at the same time securing energy, water, income and employment for this region. Solar thermal power plants are in the heart of this concept.

Load power device and system for real-time execution of hierarchical load identification algorithms

Science.gov (United States)

Yang, Yi; Madane, Mayura Arun; Zambare, Prachi Suresh

2017-11-14

A load power device includes a power input; at least one power output for at least one load; and a plurality of sensors structured to sense voltage and current at the at least one power output. A processor is structured to provide real-time execution of: (a) a plurality of load identification algorithms, and (b) event detection and operating mode detection for the at least one load.

LOAD THAT MAXIMIZES POWER OUTPUT IN COUNTERMOVEMENT JUMP

Directory of Open Access Journals (Sweden)

Pedro Jimenez-Reyes

2016-02-01

Full Text Available ABSTRACT Introduction: One of the main problems faced by strength and conditioning coaches is the issue of how to objectively quantify and monitor the actual training load undertaken by athletes in order to maximize performance. It is well known that performance of explosive sports activities is largely determined by mechanical power. Objective: This study analysed the height at which maximal power output is generated and the corresponding load with which is achieved in a group of male-trained track and field athletes in the test of countermovement jump (CMJ with extra loads (CMJEL. Methods: Fifty national level male athletes in sprinting and jumping performed a CMJ test with increasing loads up to a height of 16 cm. The relative load that maximized the mechanical power output (Pmax was determined using a force platform and lineal encoder synchronization and estimating the power by peak power, average power and flight time in CMJ. Results: The load at which the power output no longer existed was at a height of 19.9 ± 2.35, referring to a 99.1 ± 1% of the maximum power output. The load that maximizes power output in all cases has been the load with which an athlete jump a height of approximately 20 cm. Conclusion: These results highlight the importance of considering the height achieved in CMJ with extra load instead of power because maximum power is always attained with the same height. We advise for the preferential use of the height achieved in CMJEL test, since it seems to be a valid indicative of an individual's actual neuromuscular potential providing a valid information for coaches and trainers when assessing the performance status of our athletes and to quantify and monitor training loads, measuring only the height of the jump in the exercise of CMJEL.

Short-term load forecasting of power system

Science.gov (United States)

Xu, Xiaobin

2017-05-01

In order to ensure the scientific nature of optimization about power system, it is necessary to improve the load forecasting accuracy. Power system load forecasting is based on accurate statistical data and survey data, starting from the history and current situation of electricity consumption, with a scientific method to predict the future development trend of power load and change the law of science. Short-term load forecasting is the basis of power system operation and analysis, which is of great significance to unit combination, economic dispatch and safety check. Therefore, the load forecasting of the power system is explained in detail in this paper. First, we use the data from 2012 to 2014 to establish the partial least squares model to regression analysis the relationship between daily maximum load, daily minimum load, daily average load and each meteorological factor, and select the highest peak by observing the regression coefficient histogram Day maximum temperature, daily minimum temperature and daily average temperature as the meteorological factors to improve the accuracy of load forecasting indicators. Secondly, in the case of uncertain climate impact, we use the time series model to predict the load data for 2015, respectively, the 2009-2014 load data were sorted out, through the previous six years of the data to forecast the data for this time in 2015. The criterion for the accuracy of the prediction is the average of the standard deviations for the prediction results and average load for the previous six years. Finally, considering the climate effect, we use the BP neural network model to predict the data in 2015, and optimize the forecast results on the basis of the time series model.

Changes in salivary testosterone concentrations and subsequent voluntary squat performance following the presentation of short video clips.

Science.gov (United States)

Cook, Christian J; Crewther, Blair T

2012-01-01

Previous studies have shown that visual images can produce rapid changes in testosterone concentrations. We explored the acute effects of video clips on salivary testosterone and cortisol concentrations and subsequent voluntary squat performance in highly trained male athletes (n=12). Saliva samples were collected on 6 occasions immediately before and 15 min after watching a brief video clip (approximately 4 min in duration) on a computer screen. The watching of a sad, erotic, aggressive, training motivational, humorous or a neutral control clip was randomised. Subjects then performed a squat workout aimed at producing a 3 repetition maximum (3RM) lift. Significant (Psquats across all video sessions (Pfree hormone concentrations and the relative changes in testosterone closely mapped 3RM squat performance in a group of highly trained males. Thus, speculatively, using short video presentations in the pre-workout environment offers an opportunity for understanding the outcomes of hormonal change, athlete behaviour and subsequent voluntary performance. Copyright © 2011 Elsevier Inc. All rights reserved.

Unit-level voluntary turnover rates and customer service quality: implications of group cohesiveness, newcomer concentration, and size.

Science.gov (United States)

Hausknecht, John P; Trevor, Charlie O; Howard, Michael J

2009-07-01

Despite substantial growth in the service industry and emerging work on turnover consequences, little research examines how unit-level turnover rates affect essential customer-related outcomes. The authors propose an operational disruption framework to explain why voluntary turnover impairs customers' service quality perceptions. On the basis of a sample of 75 work units and data from 5,631 employee surveys, 59,602 customer surveys, and organizational records, results indicate that unit-level voluntary turnover rates are negatively related to service quality perceptions. The authors also examine potential boundary conditions related to the disruption framework. Of 3 moderators studied (group cohesiveness, group size, and newcomer concentration), results show that turnover's negative effects on service quality are more pronounced in larger units and in those with a greater concentration of newcomers.

Wireless power charging using point of load controlled high frequency power converters

Science.gov (United States)

Miller, John M.; Campbell, Steven L.; Chambon, Paul H.; Seiber, Larry E.; White, Clifford P.

2015-10-13

An apparatus for wirelessly charging a battery of an electric vehicle is provided with a point of load control. The apparatus includes a base unit for generating a direct current (DC) voltage. The base unit is regulated by a power level controller. One or more point of load converters can be connected to the base unit by a conductor, with each point of load converter comprising a control signal generator that transmits a signal to the power level controller. The output power level of the DC voltage provided by the base unit is controlled by power level controller such that the power level is sufficient to power all active load converters when commanded to do so by any of the active controllers, without generating excessive power that may be otherwise wasted.

Load following operation of nuclear power plants for meeting power system requirements

International Nuclear Information System (INIS)

Isoda, Hachiro

1987-01-01

This paper describes a calculating program on the availability factors of nuclear, thermal and pumed storage hydro power stations and some calculated results for typical three load factors, 55 %, 60 % and 71 %, are provided when the share of the nuclea power station in the generation facilities is increased. The load following requirement of the nuclear power station is also provided. Load following requirement: If there is a 10 % pumped storage hydro power station, the nuclear power station enables to be operated with its rated output up to 30 % - 35 % of its share. Its daily load following operation for 40 % and 50 % nuclear power station needs every weekend and every day respectively. Availability factor: The availability factor of the nuclear power station manages to get 80 % (maximum availability factor of the nuclear power station in this study) up to 30 % share of it with 10 % pumpued storage hydro power station. When the nuclear power station shares 40 % and 50 %, its availability factor decreases down 1 % and 5 % respectively. (author)

Modular load flow for restructured power systems

CERN Document Server

Hariharan, M V; Gupta, Pragati P

2016-01-01

In the subject of power systems, authors felt that a re-look is necessary at some conventional methods of analysis. In this book, the authors have subjected the time-honoured load flow to a close scrutiny. Authors have discovered and discussed a new load flow procedure – Modular Load Flow. Modular Load Flow explores use of power – a scalar – as source for electrical circuits which are conventionally analysed by means of phasors – the ac voltages or currents. The method embeds Kirchhoff’s circuit laws as topological property into its scalar equations and results in a unique wonderland where phase angles do not exist! Generators are shown to have their own worlds which can be superimposed to obtain the state of the composite power system. The treatment is useful in restructured power systems where stakeholders and the system operators may desire to know individual generator contributions in line flows and line losses for commercial reasons. Solution in Modular Load Flow consists of explicit expression...

The effects of training with loads that maximise power output and individualised repetitions vs. traditional power training.

Directory of Open Access Journals (Sweden)

J M Sarabia

Full Text Available It has been suggested that strength training effects (i.e. neural or structural vary, depending on the total repetitions performed and velocity loss in each training set.The aim of this study is to compare the effects of two training programmes (i.e. one with loads that maximise power output and individualised repetitions, and the other following traditional power training.Twenty-five males were divided into three groups (optimum power [OP = 10], traditional training [TT = 9] and control group [CG = 6]. The training load used for OP was individualised using loads that maximised power output (41.7% ± 5.8 of one repetition maximum [1RM] and repetitions at maximum power (4 to 9 repetitions, or 'reps'. Volume (sets x repetitions was the same for both experimental groups, while intensity for TT was that needed to perform only 50% of the maximum number of possible repetitions (i.e. 61.1%-66.6% of 1RM. The training programme ran over 11 weeks (2 sessions per week; 4-5 sets per session; 3-minute rests between sets, with pre-, intermediate and post-tests which included: anthropometry, 1RM, peak power output (PPO with 30%, 40% and 50% of 1RM in the bench press throw, and salivary testosterone (ST and cortisol (SC concentrations. Rate of perceived exertion (RPE and power output were recorded in all sessions.Following the intermediate test, PPO was increased in the OP group for each load (10.9%-13.2%. Following the post-test, both experimental groups had increased 1RM (11.8%-13.8% and PPO for each load (14.1%-19.6%. Significant decreases in PPO were found for the TT group during all sets (4.9%-15.4%, along with significantly higher RPE (37%.OP appears to be a more efficient method of training, with less neuromuscular fatigue and lower RPE.

Comparison of Power Supply Pumping of Switch-Mode Audio Power Amplifiers with Resistive Loads and Loudspeakers as Loads

DEFF Research Database (Denmark)

Knott, Arnold; Petersen, Lars Press

2013-01-01

Power supply pumping is generated by switch-mode audio power amplifiers in half-bridge configuration, when they are driving energy back into their source. This leads in most designs to a rising rail voltage and can be destructive for either the decoupling capacitors, the rectifier diodes...... in the power supply or the power stage of the amplifier. Therefore precautions are taken by the amplifier and power supply designer to avoid those effects. Existing power supply pumping models are based on an ohmic load attached to the amplifier. This paper shows the analytical derivation of the resulting...... waveforms and extends the model to loudspeaker loads. Measurements verify, that the amount of supply pumping is reduced by a factor of 4 when comparing the nominal resistive load to a loudspeaker. A simplified and more accurate model is proposed and the influence of supply pumping on the audio performance...

Current State of the Voluntary Renewable Energy Market (Presentation)

Energy Technology Data Exchange (ETDEWEB)

Heeter, J.

2013-09-01

This presentation highlights the status of the voluntary green power market in 2012. The voluntary green power market totaled more than 48 million MWh in 2012, with about 1.9 million customers participating. The supply continues to be dominated by wind, though solar is increasing its share of utility green pricing programs. Prices for voluntary renewable energy certificates (RECs) increased to above $1/MWh.

Residential response to voluntary time-of-use electricity rates

Energy Technology Data Exchange (ETDEWEB)

Mostafa Baladi, S. [Laurits R. Christensen Associates, Inc. Ames, IA 50011-1070 (United States); Herriges, Joseph A. [Iowa State University, 280D Heady Hall, Department of Economics, Iowa State University, Ames, IA 50011-1070 (United States); Sweeney, Thomas J. [MidAmerican Energy, Des Moines, Iowa (United States)

1998-09-01

The response of residential households to voluntary Time-of-Use (TOU) electricity rates is estimated using data from a recent experiment at Midwest Power Systems of Iowa. The study`s design allows us to examine both the participation decision and the customer`s load pattern changes once the TOU rate structure was in effect. Substitution elasticities between on-peak and off-peak electricity usage are estimated and compared to those obtained in earlier mandatory programs, indicating whether program volunteers are more responsive to TOU pricing than the typical household. Attitudinal questionnaires allow us to examine the role of usage perceptions in program participation

The effects of training with loads that maximise power output and individualised repetitions vs. traditional power training

Science.gov (United States)

Moya-Ramón, M.; Hernández-Davó, J. L.; Fernandez-Fernandez, J.; Sabido, R.

2017-01-01

Background It has been suggested that strength training effects (i.e. neural or structural) vary, depending on the total repetitions performed and velocity loss in each training set. Purpose The aim of this study is to compare the effects of two training programmes (i.e. one with loads that maximise power output and individualised repetitions, and the other following traditional power training). Methods Twenty-five males were divided into three groups (optimum power [OP = 10], traditional training [TT = 9] and control group [CG = 6]). The training load used for OP was individualised using loads that maximised power output (41.7% ± 5.8 of one repetition maximum [1RM]) and repetitions at maximum power (4 to 9 repetitions, or ‘reps’). Volume (sets x repetitions) was the same for both experimental groups, while intensity for TT was that needed to perform only 50% of the maximum number of possible repetitions (i.e. 61.1%–66.6% of 1RM). The training programme ran over 11 weeks (2 sessions per week; 4–5 sets per session; 3-minute rests between sets), with pre-, intermediate and post-tests which included: anthropometry, 1RM, peak power output (PPO) with 30%, 40% and 50% of 1RM in the bench press throw, and salivary testosterone (ST) and cortisol (SC) concentrations. Rate of perceived exertion (RPE) and power output were recorded in all sessions. Results Following the intermediate test, PPO was increased in the OP group for each load (10.9%–13.2%). Following the post-test, both experimental groups had increased 1RM (11.8%–13.8%) and PPO for each load (14.1%–19.6%). Significant decreases in PPO were found for the TT group during all sets (4.9%–15.4%), along with significantly higher RPE (37%). Conclusion OP appears to be a more efficient method of training, with less neuromuscular fatigue and lower RPE. PMID:29053725

Integrating Autonomous Load Controllers in Power Systems

DEFF Research Database (Denmark)

Douglass, Philip James

, but they are characterized by variable generation that is only partly predictable. Managing loads is already used in limited circumstances to improve security and efficiency of the power system. In power systems with a large penetration of variable generation, load management has large role to play in adapting consumption......Electric energy systems stand on the brink of radical change as the urgent need to reduce greenhouse gas emissions pushes more efficient utilization of energy resources and the adoption of renewable energy sources. New renewable sources such as wind and solar have a large potential......-sensitive load controller has been designed, implemented, and tested in real-life settings. Its performance demonstrated a large potential resource, in some cases greater than the average power consumption. The accuracy of load models was validated by comparison with field data. A voltage-sensitive controller...

Intrarater Reliability of Muscle Strength and Hamstring to Quadriceps Strength Imbalance Ratios During Concentric, Isometric, and Eccentric Maximal Voluntary Contractions Using the Isoforce Dynamometer.

Science.gov (United States)

Mau-Moeller, Anett; Gube, Martin; Felser, Sabine; Feldhege, Frank; Weippert, Matthias; Husmann, Florian; Tischer, Thomas; Bader, Rainer; Bruhn, Sven; Behrens, Martin

2017-08-17

To determine intrasession and intersession reliability of strength measurements and hamstrings to quadriceps strength imbalance ratios (H/Q ratios) using the new isoforce dynamometer. Repeated measures. Exercise science laboratory. Thirty healthy subjects (15 females, 15 males, 27.8 years). Coefficient of variation (CV) and intraclass correlation coefficients (ICC) were calculated for (1) strength parameters, that is peak torque, mean work, and mean power for concentric and eccentric maximal voluntary contractions; isometric maximal voluntary torque (IMVT); rate of torque development (RTD), and (2) H/Q ratios, that is conventional concentric, eccentric, and isometric H/Q ratios (Hcon/Qcon at 60 deg/s, 120 deg/s, and 180 deg/s, Hecc/Qecc at -60 deg/s and Hiso/Qiso) and functional eccentric antagonist to concentric agonist H/Q ratios (Hecc/Qcon and Hcon/Qecc). High reliability: CV 0.90; moderate reliability: CV between 10% and 20%, ICC between 0.80 and 0.90; low reliability: CV >20%, ICC Strength parameters: (a) high intrasession reliability for concentric, eccentric, and isometric measurements, (b) moderate-to-high intersession reliability for concentric and eccentric measurements and IMVT, and (c) moderate-to-high intrasession reliability but low intersession reliability for RTD. (2) H/Q ratios: (a) moderate-to-high intrasession reliability for conventional ratios, (b) high intrasession reliability for functional ratios, (c) higher intersession reliability for Hcon/Qcon and Hiso/Qiso (moderate to high) than Hecc/Qecc (low to moderate), and (d) higher intersession reliability for conventional H/Q ratios (low to high) than functional H/Q ratios (low to moderate). The results have confirmed the reliability of strength parameters and the most frequently used H/Q ratios.

Local wall power loading variations in thermonuclear fusion devices

International Nuclear Information System (INIS)

Carroll, M.C.; Miley, G.H.

1989-01-01

A 2 1/2-dimensional geometric model is presented that allows calculation of power loadings at various points on the first wall of a thermonuclear fusion device. Given average wall power loadings for brems-strahlung, cyclotron radiation charged particles, and neutrons, which are determined from various plasma-physics computation models, local wall heat loads are calculated by partitioning the plasma volume and surface into cells and superimposing the heating effects of the individual cells on selected first-wall differential areas. Heat loads from the entire plasma are thus determined as a function of position on the first-wall surface. Significant differences in local power loadings were found for most fusion designs, and it was therefore concluded that the effect of local power loading variations must be taken into account when calculating temperatures and heat transfer rates in fusion device first walls

Power quality load management for large spacecraft electrical power systems

Science.gov (United States)

Lollar, Louis F.

1988-01-01

In December, 1986, a Center Director's Discretionary Fund (CDDF) proposal was granted to study power system control techniques in large space electrical power systems. Presented are the accomplishments in the area of power system control by power quality load management. In addition, information concerning the distortion problems in a 20 kHz ac power system is presented.

Voluntary work, a diversity of forms

NARCIS (Netherlands)

Paul Dekker; Joep de Hart

2009-01-01

Original title: Vrijwilligerswerk in meervoud. By international standards, the level of participation in voluntary work in the Netherlands is high, and the signs are that this will continue. On the other hand, the type of voluntary work and the groups in which it is concentrated are changing.

[Voluntary alpha-power increasing training impact on the heart rate variability].

Science.gov (United States)

Bazanova, O M; Balioz, N V; Muravleva, K B; Skoraia, M V

2013-01-01

In order to study the effect of the alpha EEG power increasing training at heart rate variability (HRV) as the index of the autonomic regulation of cognitive functions there were follow tasks: (1) to figure out the impact of biofeedback in the voluntary increasing the power in the individual high-frequency alpha-band effect on heart rate variability and related characteristics of cognitive and emotional spheres, (2) to determine the nature of the relationship between alpha activity indices and heart rate variability, depending on the alpha-frequency EEG pattern at rest (3) to examine how the individual alpha frequency EEG pattern is reflected in changes HRV as a result of biofeedback training. Psychometric indicators of cognitive performance, the characteristics of the alpha-EEG activity and heart rate variability (HRV) as LF/HF and pNN50 were recorded in 27 healthy men aged 18-34 years, before, during, and after 10 sessions of training of voluntary increase in alpha power in the individual high-frequency alpha band with eyes closed. To determine the biofeedback effect on the alpha power increasing training, data subjects are compared in 2 groups: experimental (14) with the real and the control group (13 people)--with mock biofeedback. The follow up effect of trainings was studied through month over the 10 training sessions. Results showed that alpha biofeedback training enhanced the fluency and accuracy in cognitive performance, decreased anxiety and frontal EMG, increased resting frequency, width and power in individual upper alpha range only in participants with low baseline alpha frequency. While mock biofeedback increased resting alpha power only in participants with high baseline resting alpha frequency and did change neither cognitive performance, nor HRV indices. Biofeedback training eliminated the alpha power decrease in response to arithmetic task in both with high and low alpha frequency participants and this effect was followed up over the month. Mock

Changing Dynamics in the Voluntary Market (Presentation)

Energy Technology Data Exchange (ETDEWEB)

Heeter, J.

2014-12-01

Voluntary green power markets are those in which consumers and institutions voluntarily purchase renewable energy to match their electricity needs. This presentation, presented at the Renewable Energy Markets Conference in December 2014, outlines the voluntary market in 2013, including community choice aggregation and community solar.

Power Load Prediction Based on Fractal Theory

OpenAIRE

Jian-Kai, Liang; Cattani, Carlo; Wan-Qing, Song

2015-01-01

The basic theories of load forecasting on the power system are summarized. Fractal theory, which is a new algorithm applied to load forecasting, is introduced. Based on the fractal dimension and fractal interpolation function theories, the correlation algorithms are applied to the model of short-term load forecasting. According to the process of load forecasting, the steps of every process are designed, including load data preprocessing, similar day selecting, short-term load forecasting, and...

Illness, suffering and voluntary euthanasia.

Science.gov (United States)

Varelius, Jukka

2007-02-01

It is often accepted that we may legitimately speak about voluntary euthanasia only in cases of persons who are suffering because they are incurably injured or have an incurable disease. This article argues that when we consider the moral acceptability of voluntary euthanasia, we have no good reason to concentrate only on persons who are ill or injured and suffering.

Determination of aggregated load power consumption, under non-sinusoidal supply using an improved load model

International Nuclear Information System (INIS)

Bagheri, R.; Moghani, J.S.; Gharehpetian, G.B.; Mirtalaei, S.M.M.

2009-01-01

The harmonic content of supply voltage results in additional power losses and hence increases the load power consumption. The role of the power quality equipments on the power consumption without using an accurate model cannot be determined, too. In this paper, an improved model for aggregated loads proposed, which estimates the effects of voltage harmonics on the power consumption. The distinguished aspect of the proposed model is its parameters identification method which is based on the practical techniques, such as employing a capacitor bank or varying dummy loads in steps. The proposed model has been verified by the comparison of measured and simulated results.

Power load prediction based on GM (1,1)

Science.gov (United States)

Wu, Di

2017-05-01

Currently, Chinese power load prediction is highly focused; the paper deeply studies grey prediction and applies it to Chinese electricity consumption during the recent 14 years; through after-test test, it obtains grey prediction which has good adaptability to medium and long-term power load.

Load flow optimization and optimal power flow

CERN Document Server

Das, J C

2017-01-01

This book discusses the major aspects of load flow, optimization, optimal load flow, and culminates in modern heuristic optimization techniques and evolutionary programming. In the deregulated environment, the economic provision of electrical power to consumers requires knowledge of maintaining a certain power quality and load flow. Many case studies and practical examples are included to emphasize real-world applications. The problems at the end of each chapter can be solved by hand calculations without having to use computer software. The appendices are devoted to calculations of line and cable constants, and solutions to the problems are included throughout the book.

Public goods and private interests: The role of voluntary green power demand in achieving environmental improvements

Science.gov (United States)

Wiser, Ryan Hayes

This dissertation explores the role of consumer purchasing behavior in providing public, environmental goods. It does so by empirically evaluating one market---voluntary demand for renewable energy. The dissertation addresses the following five research questions: (1) What does early experience with green power marketing tell us about the prospects for this market to deliver environmental benefits? (2) What product design and marketing approaches might be used to increase voluntary demand? (3) What motivates non-residential customers to voluntarily purchase green power? (4) What role might public policy play in the creation of the green power market? (5) What preferences do individuals hold on the most appropriate forms of support for renewable energy? By helping to answer these questions, this dissertation seeks to better understand the gap between widespread positive attitudes for the environment and an often-anemic response to green product offerings. It contributes to not only the public goods and environmental marketing literatures, but also to contingent valuation methodology and to an emerging literature on the motivations of firms to contribute to environmental causes. The analysis performed is diverse, and includes: a literature review, a mail survey of green power marketers, a mail survey of non-residential green power customers, and contingent valuation and opinion surveys of U.S. residents. Detailed statistical analysis is performed on the data collected from the residential and non-residential surveys. The analysis reveals that customer participation in green power programs to date has been weak. The possibility that the traditional economic concept of "free riding" may explain this low response is raised, and the dissertation identifies a number of marketing approaches that might be used to partially combat this problem. Analysis of survey data shows that non-residential green power purchases have been motivated principally by altruistic concerns

The losses at power grid caused by small nonlinear loads

Directory of Open Access Journals (Sweden)

Stevanović Dejan

2013-01-01

Full Text Available The difference between registered active power and spent unregistered power represents the losses at power grid. This paper treats problems related to losses caused by nonlinear loads connected to the power grid. In recent years the load profile of power consumers turned from energy-waster linear to energysaver but non-linear loads. The main cause of the losses appears due to the lack of adequate measurement equipment. Namely, common household power meters register only active energy, while power meters for industrial application register reactive energy as well. This approach does not follow the change of the enduser profile. Tendency of improving energy efficiency brought wide use of switching mode regulators and replace old incandescent light bulb with new energy saving lamps (CFL - compact fluorescent lamp, LED bulb. Therefore, the number of non-linear load drastically increased. Registering only active component of power at consumer’s side does not depict the real profile of the consumption. Therefore, in this paper we analyse and quantify the effects of nonlinear loads at power losses. As a result we suggest an efficient method for measuring the distortion component of power. The method relays on low-cost upgrade of commercial electronic power meters. The presented results of measurements on small non-linear loads confirm the proposed technique. Besides, they prove the importance of measuring all components of apparent power and justified their use in billing policy. The implemented set-up is based on power meter manufactured by EWG of Niš. [Projekat Ministarstva nauke Republike Srbije, br. TR32004

Efficiency of voluntary closing hand and hook prostheses

NARCIS (Netherlands)

Smit, G.; Plettenburg, D.H.

2010-01-01

The Delft Institute of Prosthetics and Orthotics has started a research program to develop an improved voluntary closing, body-powered hand prosthesis. Five commercially available voluntary closing terminal devices were mechanically tested: three hands [Hosmer APRL VC hand, Hosmer Soft VC Male hand,

Administrative limits for tritium concentrations found in non-potable groundwater at nuclear power facilities

International Nuclear Information System (INIS)

Parker, R.; Hart, D.; WIllert, C.

2012-01-01

Currently, there is a regulatory limit available for tritium in drinking water, but no such limit for non-potable groundwater. Voluntary administrative limits for site groundwater may be established at nuclear power facilities to ensure minimal risk to human health and the environment, and provide guidance for investigation or other actions intended to prevent exceedances of future regulatory or guideline limits. This work presents a streamlined approach for nuclear power facilities to develop three tiers of administrative limits for tritium in groundwater so that facilities can identify abnormal/uncontrolled releases of tritium at an early stage, and take appropriate actions to investigate, control, and protect groundwater. Tier 1 represents an upper limit of background, Tier 2 represents a level between background and Tier 3, and Tier 3 represents a risk-based concentration protective of down-gradient receptors. (author)

Impact of Load Behavior on Transient Stability and Power Transfer Limitations

DEFF Research Database (Denmark)

Gordon, Mark

2009-01-01

This paper presents utility based load modeling practices and explores the interaction between loads and the power system and the effect of the interaction on transient stability and power transfer limitations. The effect of load composition is investigated at major load centers together with the......This paper presents utility based load modeling practices and explores the interaction between loads and the power system and the effect of the interaction on transient stability and power transfer limitations. The effect of load composition is investigated at major load centers together...... with the impact on rotor angle excursions of large scale generators during the transient and post-transient period. Responses of multi-induction motor stalling are also considered for different fault clearances in the system. Findings of the investigations carried out on the Eastern Australian interconnected...

Technology Roadmaps: Concentrating Solar Power

Energy Technology Data Exchange (ETDEWEB)

NONE

2010-07-01

The emerging technology known as concentrating solar power, or CSP, holds much promise for countries with plenty of sunshine and clear skies. Its electrical output matches well the shifting daily demand for electricity in places where airconditioning systems are spreading. When backed up by thermal storage facilities and combustible fuel, it offers utilities electricity that can be dispatched when required, enabling it to be used for base, shoulder and peak loads. Within about one to two decades, it will be able to compete with coal plants that emit high levels of CO2. The sunniest regions, such as North Africa, may be able to export surplus solar electricity to neighbouring regions, such as Europe, where demand for electricity from renewable sources is strong. In the medium-to-longer term, concentrating solar facilities can also produce hydrogen, which can be blended with natural gas, and provide low-carbon liquid fuels for transport and other end-use sectors. For CSP to claim its share of the coming energy revolution, concerted action is required over the next ten years by scientists, industry, governments, financing institutions and the public. This roadmap is intended to help drive these indispensable developments.

Evaluation of load rejection to house load test at 50% power for UCN 3

International Nuclear Information System (INIS)

Lee, Chang Gyun; Sohn, Suk Whun; Sohn, Jong Joo; Seo, Jong Tae; Lee, Sang Keun; Kim, Yong Sung; Nam, Kyu Won; Jung, Yang Mook; Chae, Kyeong Sik; Koh, Bum Jae; Oh, Chul Sung; Park, Hee Chool

1998-01-01

The Load Rejection to House Load test at 50% power was successfully performed during the UCN 3 PAT period. In this test, all plant control systems automatically controlled the plant from 50% power to house load operation mode. The KISPAC code, which was used in the performance analysis during the design process of UCN 3 and 4, predictions of the test agreed with the measured data demonstrating the validity of the code as well as completeness of the plant design

Real-Time Load-Side Control of Electric Power Systems

Science.gov (United States)

Zhao, Changhong

Two trends are emerging from modern electric power systems: the growth of renewable (e.g., solar and wind) generation, and the integration of information technologies and advanced power electronics. The former introduces large, rapid, and random fluctuations in power supply, demand, frequency, and voltage, which become a major challenge for real-time operation of power systems. The latter creates a tremendous number of controllable intelligent endpoints such as smart buildings and appliances, electric vehicles, energy storage devices, and power electronic devices that can sense, compute, communicate, and actuate. Most of these endpoints are distributed on the load side of power systems, in contrast to traditional control resources such as centralized bulk generators. This thesis focuses on controlling power systems in real time, using these load side resources. Specifically, it studies two problems. (1) Distributed load-side frequency control: We establish a mathematical framework to design distributed frequency control algorithms for flexible electric loads. In this framework, we formulate a category of optimization problems, called optimal load control (OLC), to incorporate the goals of frequency control, such as balancing power supply and demand, restoring frequency to its nominal value, restoring inter-area power flows, etc., in a way that minimizes total disutility for the loads to participate in frequency control by deviating from their nominal power usage. By exploiting distributed algorithms to solve OLC and analyzing convergence of these algorithms, we design distributed load-side controllers and prove stability of closed-loop power systems governed by these controllers. This general framework is adapted and applied to different types of power systems described by different models, or to achieve different levels of control goals under different operation scenarios. We first consider a dynamically coherent power system which can be equivalently modeled with

Real power regulation for the utility power grid via responsive loads

Science.gov (United States)

McIntyre, Timothy J [Knoxville, TN; Kirby, Brendan J [Knoxville, TN; Kisner, Roger A

2009-05-19

A system for dynamically managing an electrical power system that determines measures of performance and control criteria for the electric power system, collects at least one automatic generation control (AGC) input parameter to at least one AGC module and at least one automatic load control (ALC) input parameter to at least one ALC module, calculates AGC control signals and loads as resources (LAR) control signals in response to said measures of performance and control criteria, propagates AGC control signals to power generating units in response to control logic in AGC modules, and propagates LAR control signals to at least one LAR in response to control logic in ALC modules.

Brain Functional Connectivity is Different during VoluntaryConcentric and Eccentric Muscle Contraction

Directory of Open Access Journals (Sweden)

Wan X Yao

2016-11-01

Full Text Available Previous studies report greater activation in the cortical motor network in controlling eccentric contraction (EC than concentric contraction (CC of human skeletal muscles despite lower activation level of the muscle associated with EC. It is unknown, however, whether the strength of functional coupling between the primary motor cortex (M1 and other involved areas in the brain differs as voluntary movements are controlled by a network of regions in the primary, secondary and association cortices. Examining fMRI-based functional connectivity (FC offers an opportunity to measure strength of such coupling. To address the question, we examined functional MRI (fMRI data acquired during EC and CC (20 contractions each with similar movement distance and speed of the right first dorsal interosseous (FDI muscle in 11 young (20-32 years and healthy individuals and estimated FC between the M1 and a number of cortical regions in the motor control network. The major findings from the behavioral and fMRI-based FC analysis were that (1 no significant differences were seen in movement distance, speed and stability between the EC and CC; (2 significantly stronger mean FC was found for CC than EC. Our finding provides novel insights for a better understanding of the control mechanisms underlying voluntary movements produced by EC and CC. The finding is potentially helpful for guiding the development of targeted sport training and/or therapeutic programs for performance enhancement and injury prevention.

Modified bond model for shear in slabs under concentrated loads

NARCIS (Netherlands)

Lantsoght, E.O.L.; Van der Veen, C.; De Boer, A.

2015-01-01

Slabs subjected to concentrated loads close to supports, as occurring for truck loads on slab bridges, are less studied than beams in shear or slab-column connections in punching. To predict the shear capacity for this case, the Bond Model for concentric punching shear was studied initially.

Impact of extreme load requirements and quality assurance on nuclear power plant costs

International Nuclear Information System (INIS)

Stevenson, J.D.

1993-01-01

Definitive costs, applicable to nuclear power plant concrete structures, as a function of National Regulatory Requirements, standardization, the effect of extreme load design associated with both design basis accidents and extreme external events and quality assurance are difficult to develop since such effects are interrelated and not only differ widely from country to country, project to project but also vary in time. Table 1 shows an estimate of the of the overall plant cost effects of external event extreme load design on nuclear power plant design for the U.S -and selected foreign countries for which experience with LWRs exist- Germany is the most expensive primarily due to a military aircraft crash resistance. However, the German requirement for 4 safeguards trains rather than 2 and the containment design requirement to consider one Steam Generator blowdown concurrent with a RCS blowdown. This presentation will concentrate on the direct current impact extreme load design and quality assurance have on concrete structures, systems and components for nuclear plants. This presentation is considered timely due to the increased interest in the c potential backfit of Eastern European nuclear power stations of the WWER 440 and WWER 1000 types which typically did not consider the extreme loads identified in Table 1 and accident loads in Table 3 and quality assurance in Table 5 in their original design. Concrete structures in particular are highlighted because they typically form the last barrier to radioactive release from the containment and other Safety Related Structures

Evaluation of Load Rejection to house load test at 50% power for UCN 3

Energy Technology Data Exchange (ETDEWEB)

Lee, Chang Gyun; Sohn, Suk Whun; Sohn, Jong Joo; Seo, Jong Tae; Lee, Sang Keun [Korea Power Engineering Company, Inc., Seoul (Korea, Republic of); Kim, Yong Sung; Nam, Kyu Won; Jung, Yang Mook; Chae, Kyeong Sik; Koh, Bum Jae; Oh, Chul Sung; Park, Hee Chool [Korea Electric Power Corporation, Taejon (Korea, Republic of)

1999-12-31

The Load Rejection to House Load test at 50% power was successfully performed during the UCN 3 PAT period. In this test, all plant control systems automatically controlled the plant from 50% power to house load operation mode. The KISPAC code, which was used in the performance analysis during the design process of UCN 3 and 4, predictions of the test agreed with the measured data demonstrating the validity of the code as well as the completeness of the plant design. 3 refs., 8 figs., 1 tab. (Author)

Evaluation of Load Rejection to house load test at 50% power for UCN 3

Energy Technology Data Exchange (ETDEWEB)

Lee, Chang Gyun; Sohn, Suk Whun; Sohn, Jong Joo; Seo, Jong Tae; Lee, Sang Keun [Korea Power Engineering Company, Inc., Seoul (Korea, Republic of); Kim, Yong Sung; Nam, Kyu Won; Jung, Yang Mook; Chae, Kyeong Sik; Koh, Bum Jae; Oh, Chul Sung; Park, Hee Chool [Korea Electric Power Corporation, Taejon (Korea, Republic of)

1998-12-31

The Load Rejection to House Load test at 50% power was successfully performed during the UCN 3 PAT period. In this test, all plant control systems automatically controlled the plant from 50% power to house load operation mode. The KISPAC code, which was used in the performance analysis during the design process of UCN 3 and 4, predictions of the test agreed with the measured data demonstrating the validity of the code as well as the completeness of the plant design. 3 refs., 8 figs., 1 tab. (Author)

Price, environment and security: Exploring multi-modal motivation in voluntary residential peak demand response

International Nuclear Information System (INIS)

Gyamfi, Samuel; Krumdieck, Susan

2011-01-01

Peak demand on electricity grids is a growing problem that increases costs and risks to supply security. Residential sector loads often contribute significantly to seasonal and daily peak demand. Demand response projects aim to manage peak demand by applying price signals and automated load shedding technologies. This research investigates voluntary load shedding in response to information about the security of supply, the emission profile and the cost of meeting critical peak demand in the customers' network. Customer willingness to change behaviour in response to this information was explored through mail-back survey. The diversified demand modelling method was used along with energy audit data to estimate the potential peak load reduction resulting from the voluntary demand response. A case study was conducted in a suburb of Christchurch, New Zealand, where electricity is the main source for water and space heating. On this network, all water heating cylinders have ripple-control technology and about 50% of the households subscribe to differential day/night pricing plan. The survey results show that the sensitivity to supply security is on par with price, with the emission sensitivity being slightly weaker. The modelling results show potential 10% reduction in critical peak load for aggregate voluntary demand response. - Highlights: → Multiple-factor behaviour intervention is necessarily for effective residential demand response. → Security signals can achieve result comparable to price. → The modelling results show potential 10% reduction in critical peak load for aggregate voluntary demand response. → New Zealand's energy policy should include innovation and development of VDR programmes and technologies.

Concentrating Solar Power. Technology Roadmap

Energy Technology Data Exchange (ETDEWEB)

NONE

2010-10-15

Concentrating solar power can contribute significantly to the world's energy supply. As shown in this roadmap, this decade is a critical window of opportunity during which CSP could become a competitive source of electrical power to meet peak and intermediate loads in the sunniest parts of the world. This roadmap identifies technology, economy and policy goals and milestones needed to support the development and deployment of CSP, as well as ongoing advanced research in CSF. It also sets out the need for governments to implement strong, balanced policies that favour rapid technological progress, cost reductions and expanded industrial manufacturing of CSP equipment to enable mass deployment. Importantly, this roadmap also establishes a foundation for greater international collaboration. The overall aim of this roadmap is to identify actions required - on the part of all stakeholders - to accelerate CSP deployment globally. Many countries, particularly in emerging regions, are only just beginning to develop CSP. Accordingly, milestone dates should be considered as indicative of urgency, rather than as absolutes. This roadmap is a work in progress. As global CSP efforts advance and an increasing number of CSP applications are developed, new data will provide the basis for updated analysis. The IEA will continue to track the evolution of CSP technology and its impacts on markets, the power sector and regulatory environments, and will update its analysis and set additional tasks and milestones as new learning comes to light.

High Cable Forces Deteriorate Pinch Force Control in Voluntary-Closing Body-Powered Prostheses.

Directory of Open Access Journals (Sweden)

Mona Hichert

Full Text Available It is generally asserted that reliable and intuitive control of upper-limb prostheses requires adequate feedback of prosthetic finger positions and pinch forces applied to objects. Body-powered prostheses (BPPs provide the user with direct proprioceptive feedback. Currently available BPPs often require high cable operation forces, which complicates control of the forces at the terminal device. The aim of this study is to quantify the influence of high cable forces on object manipulation with voluntary-closing prostheses.Able-bodied male subjects were fitted with a bypass-prosthesis with low and high cable force settings for the prehensor. Subjects were requested to grasp and transfer a collapsible object as fast as they could without dropping or breaking it. The object had a low and a high breaking force setting.Subjects conducted significantly more successful manipulations with the low cable force setting, both for the low (33% more and high (50% object's breaking force. The time to complete the task was not different between settings during successful manipulation trials.High cable forces lead to reduced pinch force control during object manipulation. This implies that low cable operation forces should be a key design requirement for voluntary-closing BPPs.

Assessing Power System Stability Following Load Changes and Considering Uncertainty

Directory of Open Access Journals (Sweden)

D. V. Ngo

2018-04-01

Full Text Available An increase in load capacity during the operation of a power system usually causes voltage drop and leads to system instability, so it is necessary to monitor the effect of load changes. This article presents a method of assessing the power system stability according to the load node capacity considering uncertainty factors in the system. The proposed approach can be applied to large-scale power systems for voltage stability assessment in real-time.

Testable, fault-tolerant power interface circuit for normally de-energized loads

International Nuclear Information System (INIS)

Hager, R.E.

1987-01-01

A power interface circuit is described for supplying power from a power line to a normally de-energized process control apparatus in a pressurized light water nuclear power system in dependence upon three input signals, comprising: voter means for supplying power to the normally de-energized load when at least two of the three input signals indicate that the normally de-energized load should be activated; a normally closed switch, operatively connected to the power line and the voter means, for supplying power to the voter means during ordinary operation; a first resistor operatively connected to the power line; a current detector operatively connected to the first resistor and the voter means; a second resistor operatively connected to the current detector and ground; and current sensor means, operatively connected between the voter means and the normally de-energized load, for detecting the power supplied to the normally de-energized load by the voter means

Muscle power output properties using the stretch-shortening cycle of the upper limb and their relationships with a one-repetition maximum bench press.

Science.gov (United States)

Miyaguchi, Kazuyoshi; Demura, Shinichi

2006-05-01

The purpose of this study was to examine the output properties of muscle power by the dominant upper limb using SSC, and the relationships between the power output by SSC and a one-repetition maximum bench press (1 RM BP) used as a strength indicator of the upper body. Sixteen male athletes (21.4+/-0.9 yr) participated in this study. They pulled a load of 40% of maximum voluntary contraction (MVC) at a stretch by elbow flexion of the dominant upper limb in the following three preliminary conditions: static relaxed muscle state (SR condition), isometric muscle contraction state (ISO condition), and using SSC (SSC condition). The velocity with a wire load via a pulley during elbow flexion was measured accurately using a power instrument with a rotary encoder, and the muscle power curve was drawn from the product of the velocity and load. Significant differences were found among all evaluation parameters of muscle power exerted from the above three conditions and the parameters regarding early power output during concentric contraction were larger in the SSC condition than the SR and ISO conditions. The parameters on initial muscle contraction velocity when only using SSC significantly correlated with 1 RM BP (r=0.60-0.62). The use of SSC before powerful elbow flexion may contribute largely to early explosive power output during concentric contraction. Bench press capacity relates to a development of the above early power output when using SSC.

Sliding mode load frequency control for multi-area time-delay power system with wind power integration

DEFF Research Database (Denmark)

Mi, Yang; Hao, Xuezhi; Liu, Yongjuan

2017-01-01

The interconnected time-delay power system has become an important issue for the open communication network. Meanwhile, due to the output power fluctuation of integrated wind energy, load frequency control (LFC) for power system with variable sources and loads has become more complicated. The novel...

Market Brief. Status of the Voluntary Renewable Energy Certificate Market (2011 Data)

Energy Technology Data Exchange (ETDEWEB)

Heeter, Jenny [National Renewable Energy Lab. (NREL), Golden, CO (United States); Armstrong, Philip [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bird, Lori [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2012-09-01

This report documents the status and trends of U.S. 'voluntary' markets -- those in which consumers and institutions purchase renewable energy to match their electricity needs on a voluntary basis. Voluntary REC markets continue to exhibit growth and spur renewable energy development. Voluntary green power markets provide an additional revenue stream for renewable energy projects and raise consumer awareness of the benefits of renewable energy. Although a full estimate of the size of the voluntary market is not available for 2011, this review uses indicative metrics to capture 2011 voluntary market trends.

Market Brief: Status of the Voluntary Renewable Energy Certificate Market (2011 Data)

Energy Technology Data Exchange (ETDEWEB)

Heeter, J.; Armstrong, P.; Bird, L.

2012-09-01

This report documents the status and trends of U.S. 'voluntary' markets -- those in which consumers and institutions purchase renewable energy to match their electricity needs on a voluntary basis. Voluntary REC markets continue to exhibit growth and spur renewable energy development. Voluntary green power markets provide an additional revenue stream for renewable energy projects and raise consumer awareness of the benefits of renewable energy. Although a full estimate of the size of the voluntary market is not available for 2011, this review uses indicative metrics to capture 2011 voluntary market trends.

An Optimization Framework for Load and Power Distribution in Wind Farms

DEFF Research Database (Denmark)

Soleimanzadeh, Maryam; Wisniewski, Rafal; Kanev, Stoyan

2012-01-01

The aim of this paper is to develop a controller for wind farms to optimize the load and power distribution. In this regard, the farm controller calculates the power reference signals for individual wind turbine controllers such that the sum of the power references tracks the power demanded...... by a system operator. Moreover, the reference signals are determined to reduce the load acting on wind turbines at low frequencies. Therefore, a trade-off is made for load and power control, which is formulated as an optimization problem. Afterwards, the optimization problem for the wind farm modeled...

Effect of vibration during fatiguing resistance exercise on subsequent muscle activity during maximal voluntary isometric contractions.

Science.gov (United States)

McBride, Jeffrey M; Porcari, John P; Scheunke, Mark D

2004-11-01

This investigation was designed to determine if vibration during fatiguing resistance exercise would alter associated patterns of muscle activity. A cross-over design was employed with 8 subjects completing a resistance exercise bout once with a vibrating dumbbell (V) (44 Hz, 3 mm displacement) and once without vibration (NV). For both exercise bouts, 10 sets were performed with a load that induced concentric muscle failure during the 10th repetition. The appropriate load for each set was determined during a pretest. Each testing session was separated by 1 week. Electromyography (EMG) was obtained from the biceps brachii muscle at 12 different time points during a maximum voluntary contraction (MVC) at a 170 degrees elbow angle after each set of the dumbbell exercise. The time points were as follows: pre (5 minutes before the resistance exercise bout), T1-T10 (immediately following each set of resistance exercise), and post (15 minutes after the resistance exercise bout). EMG was analyzed for median power frequency (MPF) and maximum (mEMG). NV resulted in a significant decrease in MPF at T1-T4 (p recruitment of high threshold motor units during fatiguing contractions. This may indicate the usage of vibration with resistance exercise as an effective tool for strength training athletes.

Biomechanical comparison between concentrated, follower, and muscular loads of the lumbar column.

Science.gov (United States)

Shih, Kao-Shang; Weng, Pei-Wei; Lin, Shang-Chih; Chen, Yi-Tzu; Cheng, Cheng-Kung; Lee, Chian-Her

2016-10-01

Experimental and numerical methods have been extensively used to simulate the lumbar kinematics and mechanics. One of the basic parameters is the lumbar loads. In the literature, both concentrated and distributed loads have been assumed to simulate the in vivo lumbar loads. However, the inconsistent loads between those studies exist and make the comparison of their results controversial. Using finite-element method, this study aimed to numerically compare the effects of the concentrated, follower, and muscular loads on the lumbar biomechanics during flexion. Two conditions of equivalent and simple constraints were simulated. The equivalent condition assumes the identical flexion at the L1 level and loads at the L5 level for the three types of loads. Another condition is to remove such kinematic and mechanical constraints on the lumbar. The comparison indices were flexed profile, distributed stress, and transferred loads of the discs and vertebrae at the different levels. The results showed that the three modes in the equivalent condition show the nearly same flexed profiles. In the simple condition, however, the L1 vertebra of the concentrated mode anteriorly translates about 3 and 5 times that of the follower and muscular mode, respectively. By contrast, the flexion profiles of the follower and muscular are comparable. In the equivalent condition, all modes consistently show the gradually increasing stress and loads toward the caudal levels. The results of both concentrated and muscular modes exhibit the quite comparable trends and even magnitudes. In the simple condition, however, the removal of flexion and load constraints makes the results of the concentrated mode significantly different from its counterparts. In both conditions, the predictedindices of the follower mode are more uniform along the lumbar. In conclusion, the kinematic and mechanical constraints significantly affect the profile, stress, and loads of the three modes. In the equivalent condition

Fatigue Load Sensitivity Based Optimal Active Power Dispatch For Wind Farms

DEFF Research Database (Denmark)

Zhao, Haoran; Wu, Qiuwei; Huang, Shaojun

2017-01-01

This paper proposes an optimal active power dispatch algorithm for wind farms based on Wind Turbine (WT) load sensitivity. The control objectives include tracking power references from the system operator and minimizing fatigue loads experienced by WTs. The sensitivity of WT fatigue loads to power...... sensitivity are derived, which significantly improves the computation efficiency of the local WT controller. The proposed algorithm can be implemented in different active power control schemes. Case studies were conducted with a wind farm under balance control for both low and high wind conditions...

Improving automated load flexibility of nuclear power plants with ALFC

Energy Technology Data Exchange (ETDEWEB)

Kuhn, Andreas [AREVA GmbH, Karlstein (Germany). Plant Control/Training; Klaus, Peter [E.ON NPP Isar 2, Essenbach (Germany). Plant Operation/Production Engineering

2016-07-01

In several German and Swiss Nuclear Power Plants with Pressurized Water Reactor (PWR) the control of the reactor power was and will be improved in order to be able to support the energy transition with increasing volatile renewable energy in the grid by flexible load operation according to the need of the load dispatcher (power system stability). Especially regarding the mentioned German NPPs with a nominal electric power of approx. 1,500 MW, the general objectives are the main automated grid relevant operation modes. The new possibilities of digital I and C (as TELEPERM {sup registered} XS) enable the automation of the operating modes provided that manual support is no longer necessary. These possibilities were and will be implemented by AREVA within the ALFC-projects. Manifold adaption algorithms to the reactor physical variations during the nuclear load cycle enable a precise control of the axial power density distribution and of the reactivity management in the reactor core. Finally this is the basis for a highly automated load flexibility with the parallel respect and surveillance of the operational limits of a PWR.

Improving automated load flexibility of nuclear power plants with ALFC

Energy Technology Data Exchange (ETDEWEB)

Kuhn, Andreas [AREVA GmbH, Karlstein (Germany). Section Manager Training; Klaus, Peter [Preussenelektra NPP, Essenbach (Germany). Production Engineering

2017-03-15

In several German and Swiss Nuclear Power Plants with Pressurized Water Reactor (PWR) the control of the reactor power was and will be improved in order to be able to support the energy transition with increasing volatile renewable energy in the grid by flexible load operation according to the need of the load dispatcher (power system stability). Especially regarding the mentioned German NPPs with a nominal electric power of approx. 1500 MW, the general objectives are several automated grid relevant operation modes. The new possibilities of digital I and C (as TELEPERM {sup registered} XS) enable the automation of this operating modes provided that manual support is no longer necessary. These possibilities were and will be implemented by AREVA within the ALFC-projects. Manifold adaption algorithms to the reactor physical variations during the nuclear load cycle enable a precise control of the axial power density distribution and of the reactivity manage - ment in the reactor core. Finally this is the basis for a highly automated load flexibility with the parallel respect and surveillance of the operational limits of a PWR.

Modeling a constant power load for nickel-hydrogen battery testing using SPICE

Science.gov (United States)

Bearden, Douglas B.; Lollar, Louis F.; Nelms, R. M.

1990-01-01

The effort to design and model a constant power load for the HST (Hubble Space Telescope) nickel-hydrogen battery tests is described. The constant power load was designed for three different simulations on the batteries: life cycling, reconditioning, and capacity testing. A dc-dc boost converter was designed to act as this constant power load. A boost converter design was chosen because of the low test battery voltage (4 to 6 VDC) generated and the relatively high power requirement of 60 to 70 W. The SPICE model was shown to consistently predict variations in the actual circuit as various designs were attempted. It is concluded that the confidence established in the SPICE model of the constant power load ensures its extensive utilization in future efforts to improve performance in the actual load circuit.

Analytical solution for a strained reinforcement layer bonded to lip-shaped crack under remote mode Ⅲ uniform load and concentrated load

Institute of Scientific and Technical Information of China (English)

You-wen LIU; Chao XIE; Chun-zhi JIANG; Qi-hong FANG

2010-01-01

In this paper,the analytical solution of stress field for a strained reinforcement layer bonded to a lip-shaped crack under a remote mode Ⅲ uniform load and a concentrated load is obtained explicitly in the series form by using the technical of conformal mapping and the method of analytic continuation.The effects of material combinations,bond of interface and geometric configurations on interfacial stresses generated by eigenstrain,remote load and concentrated load are studied.The results show that the stress concentration and interfacial stresses can be reduced by rational material combinations and geometric configurations designs for different load forms.

Effect of External Loading on Force and Power Production During Plyometric Push-ups.

Science.gov (United States)

Hinshaw, Taylour J; Stephenson, Mitchell L; Sha, Zhanxin; Dai, Boyi

2018-04-01

Hinshaw, TJ, Stephenson, ML, Sha, Z, and Dai, B. Effect of external loading on force and power production during plyometric push-ups. J Strength Cond Res 32(4): 1099-1108, 2018-One common exercise to train upper-body strength and power is the push-up. Training at the loads that would produce the greatest power is an effective way to increase peak power. The purpose of the current study was to quantify the changes in peak force, peak power, and peak velocity among a modified plyometric push-up and plyometric push-ups with or without external loading in physically active young adults. Eighteen male and 17 female participants completed 4 push-ups: (a) modified plyometric push-up on the knees, (b) plyometric push-up without external loading, (c) plyometric push-up with an external load of 5% of body weight, and (d) plyometric push-up with an external load of 10% of body weight. Two force platforms were set up to collect vertical ground reaction forces at the hands and feet. The modified plyometric push-up demonstrated the lowest force, power, and velocity (5.4≥ Cohen's dz ≥1.2). Peak force and force at peak velocity increased (3.8≥ Cohen's dz ≥0.3) and peak velocity and velocity at peak power decreased (1.4≥ Cohen's dz ≥0.8) for the push-up without external loading compared with the 2 push-ups with external loading. No significant differences were observed for peak power among the push-ups with or without external loading (0.4≥ Cohen's dz ≥0.1). Although peak power is similar with or without external loading, push-ups without external loading may be more beneficial for a quick movement, and push-ups with external loading may be more beneficial for a greater force production.

Poloidal variations in toroidal fusion reactor wall power loadings

International Nuclear Information System (INIS)

Carroll, M.C.; Miley, G.H.

1985-01-01

A geometric formulation is developed by the authors for determining poloidal variations in bremmstrahlung, cyclotron radiation, and neutron wall power loadings in toroidal fusion devices. Assuming toroidal symmetry and utilizing a numerical model which partitions the plasma into small cells, it was generally found that power loadings are highest on the outer surface of the torus, although variations are not as large as some have predicted. Results are presented for various plasma power generation configurations, plasma volume fractions, and toroidal aspect ratios, and include plasma and wall blockage effects

Biofeedback, voluntary control, and human potential.

Science.gov (United States)

Norris, P

1986-03-01

This paper examines some of the philosophical and scientific relationships involving self-control, voluntary control, and psychophysiologic self-regulation. The role of biofeedback in mediating conscious and unconscious processes is explored. Demonstrations of superior voluntary control and its relationship to belief, confidence, and expectation are examined. Biofeedback demonstrates the potential of control to oneself, creating confidence in one's ability to establish enhanced and peak performance in athletics, education, and psychophysiologic therapy. Emphasis is placed on the power of images in all human functioning, and in enhancing human potential.

Short-Term Forecasting of Loads and Wind Power for Latvian Power System: Accuracy and Capacity of the Developed Tools

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Radziukynas V.

2016-04-01

Full Text Available The paper analyses the performance results of the recently developed short-term forecasting suit for the Latvian power system. The system load and wind power are forecasted using ANN and ARIMA models, respectively, and the forecasting accuracy is evaluated in terms of errors, mean absolute errors and mean absolute percentage errors. The investigation of influence of additional input variables on load forecasting errors is performed. The interplay of hourly loads and wind power forecasting errors is also evaluated for the Latvian power system with historical loads (the year 2011 and planned wind power capacities (the year 2023.

Short-Term Forecasting of Loads and Wind Power for Latvian Power System: Accuracy and Capacity of the Developed Tools

Science.gov (United States)

Radziukynas, V.; Klementavičius, A.

2016-04-01

The paper analyses the performance results of the recently developed short-term forecasting suit for the Latvian power system. The system load and wind power are forecasted using ANN and ARIMA models, respectively, and the forecasting accuracy is evaluated in terms of errors, mean absolute errors and mean absolute percentage errors. The investigation of influence of additional input variables on load forecasting errors is performed. The interplay of hourly loads and wind power forecasting errors is also evaluated for the Latvian power system with historical loads (the year 2011) and planned wind power capacities (the year 2023).

Simplified Entropic Model for the Evaluation of Suspended Load Concentration

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Domenica Mirauda

2018-03-01

Full Text Available Suspended sediment concentration is a key aspect in the forecasting of river evolution dynamics, as well as in water quality assessment, evaluation of reservoir impacts, and management of water resources. The estimation of suspended load often relies on empirical models, of which efficiency is limited by their analytic structure or by the need for calibration parameters. The present work deals with a simplified fully-analytical formulation of the so-called entropic model in order to reproduce the vertical distribution of sediment concentration. The simplification consists in the leading order expansion of the generalized spatial coordinate of the entropic velocity profile that, strictly speaking, applies to the near-bed region, but that provides acceptable results also near the free surface. The proposed closed-form solution, which highlights the interplay among channel morphology, stream power, secondary flows, and suspended transport features, allows reducing the needed number of field measurements and, therefore, the time of field activities. Its accuracy and robustness were successfully tested based on the comparison with laboratory data reported in literature.

Urban Saturated Power Load Analysis Based on a Novel Combined Forecasting Model

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Huiru Zhao

2015-03-01

Full Text Available Analysis of urban saturated power loads is helpful to coordinate urban power grid construction and economic social development. There are two different kinds of forecasting models: the logistic curve model focuses on the growth law of the data itself, while the multi-dimensional forecasting model considers several influencing factors as the input variables. To improve forecasting performance, a novel combined forecasting model for saturated power load analysis was proposed in this paper, which combined the above two models. Meanwhile, the weights of these two models in the combined forecasting model were optimized by employing a fruit fly optimization algorithm. Using Hubei Province as the example, the effectiveness of the proposed combined forecasting model was verified, demonstrating a higher forecasting accuracy. The analysis result shows that the power load of Hubei Province will reach saturation in 2039, and the annual maximum power load will reach about 78,630 MW. The results obtained from this proposed hybrid urban saturated power load analysis model can serve as a reference for sustainable development for urban power grids, regional economies, and society at large.

Effects of concentric vs eccentric loading on cardiovascular ...

African Journals Online (AJOL)

Effects of concentric vs eccentric loading on cardiovascular variables and ECG. Madan Bhavna1*, Sarika, Sandhu J.S1. 1. Department of Sports Medicine and Physiotherapy Guru Nanak Dev University; ..... psychological and performance.

Concentrating Solar Power Projects - Planta Solar 20 | Concentrating Solar

Science.gov (United States)

Power | NREL 20 This page provides information on Planta Solar 20, a concentrating solar power Solar's Planta Solar 20 (PS20) is a 20-megawatt power tower plant being constructed next to the PS10 tower and increasing incident solar radiation capture will increase net electrical power output by 10

Optimal load allocation of complex ship power plants

International Nuclear Information System (INIS)

Baldi, Francesco; Ahlgren, Fredrik; Melino, Francesco; Gabrielii, Cecilia; Andersson, Karin

2016-01-01

Highlights: • The optimal operation of the prime movers of hybrid ship power plants is addressed. • Both mechanical, electric and thermal power demand are considered. • The problem is modelled as a mixed integer-nonlinear programming problem. • Up to 3% savings can be achieved with hybrid power plants. • Including the thermal power demand improves the solution by up to 4%. - Abstract: In a world with increased pressure on reducing fuel consumption and carbon dioxide emissions, the cruise industry is growing in size and impact. In this context, further effort is required for improving the energy efficiency of cruise ship energy systems. In this paper, we propose a generic method for modelling the power plant of an isolated system with mechanical, electric and thermal power demands and for the optimal load allocation of the different components that are able to fulfil the demand. The optimisation problem is presented in the form of a mixed integer linear programming (MINLP) problem, where the number of engines and/or boilers running is represented by the integer variables, while their respective load is represented by the non-integer variables. The individual components are modelled using a combination of first-principle models and polynomial regressions, thus making the system nonlinear. The proposed method is applied to the load-allocation problem of a cruise ship sailing in the Baltic Sea, and used to compare the existing power plant with a hybrid propulsion plant. The results show the benefits brought by using the proposing method, which allow estimating the performance of the hybrid system (for which the load allocation is a non-trivial problem) while also including the contribution of the heat demand. This allows showing that, based on a reference round voyage, up to 3% savings could be achieved by installing the proposed system, compared to the existing one, and that a NPV of 11 kUSD could be achieved already 5 years after the installation of the

Artificial bee colony algorithm for economic load dispatch with wind power energy

Directory of Open Access Journals (Sweden)

Safari Amin

2016-01-01

Full Text Available This paper presents an efficient Artificial Bee Colony (ABC algorithm for solving large scale economic load dispatch (ELD problems in power networks. To realize the ELD, the valve-point loading effect, system load demand, power losses, ramp rate limits and prohibited operation zones are considered here. Simulations were performed on four different power systems with 3, 6, 15 and 40 generating units and the results are compared with two forms of power systems, one power system is with a wind power generator and other power system is without a wind power generator. The results of this study reveal that the proposed approach is able to find appreciable ELD solutions than those of previous algorithms.

Temperature rise of cyclicly loaded power cables

Energy Technology Data Exchange (ETDEWEB)

Brakelmann, H

1984-09-01

A calculation method for the current ratings of cyclicly loaded power cables is introduced, taking into account optional shapes of the load cycle as well as the drying-out of the soil. The method is based on the Fourier-analysis of the loss cycle, representing an extension of the calculation method of VDE 0298. It is shown, that the ''VDE-method'' gives good results for the thermal resistances, if an ''utility load cycle'' in accordance with VDE 0298 is supposed. Only for cycles deviating essentially from the utility load cycle, the thermal resistances calculated by the ''VDE-method'' may be too great. In these cases the represented method is advantageous and can be processed by the aid of microcomputers.

Improving electrical power systems reliability through locally controlled distributed curtailable load

Science.gov (United States)

Dehbozorgi, Mohammad Reza

2000-10-01

Improvements in power system reliability have always been of interest to both power companies and customers. Since there are no sizable electrical energy storage elements in electrical power systems, the generated power should match the load demand at any given time. Failure to meet this balance may cause severe system problems, including loss of generation and system blackouts. This thesis proposes a methodology which can respond to either loss of generation or loss of load. It is based on switching of electric water heaters using power system frequency as the controlling signal. The proposed methodology encounters, and the thesis has addressed, the following associated problems. The controller must be interfaced with the existing thermostat control. When necessary to switch on loads, the water in the tank should not be overheated. Rapid switching of blocks of load, or chattering, has been considered. The contributions of the thesis are: (A) A system has been proposed which makes a significant portion of the distributed loads connected to a power system to behave in a predetermined manner to improve the power system response during disturbances. (B) The action of the proposed system is transparent to the customers. (C) The thesis proposes a simple analysis for determining the amount of such loads which might be switched and relates this amount to the size of the disturbances which can occur in the utility. (D) The proposed system acts without any formal communication links, solely using the embedded information present system-wide. (E) The methodology of the thesis proposes switching of water heater loads based on a simple, localized frequency set-point controller. The thesis has identified the consequent problem of rapid switching of distributed loads, which is referred to as chattering. (F) Two approaches have been proposed to reduce chattering to tolerable levels. (G) A frequency controller has been designed and built according to the specifications required to

Determination of strength exercise intensities based on the load-power-velocity relationship.

Science.gov (United States)

Jandačka, Daniel; Beremlijski, Petr

2011-06-01

The velocity of movement and applied load affect the production of mechanical power output and subsequently the extent of the adaptation stimulus in strength exercises. We do not know of any known function describing the relationship of power and velocity and load in the bench press exercise. The objective of the study is to find a function modeling of the relationship of relative velocity, relative load and mechanical power output for the bench press exercise and to determine the intensity zones of the exercise for specifically focused strength training of soccer players. Fifteen highly trained soccer players at the start of a competition period were studied. The subjects of study performed bench presses with the load of 0, 10, 30, 50, 70 and 90% of the predetermined one repetition maximum with maximum possible speed of movement. The mean measured power and velocity for each load (kg) were used to develop a multiple linear regression function which describes the quadratic relationship between the ratio of power (W) to maximum power (W) and the ratios of the load (kg) to one repetition maximum (kg) and the velocity (m•s(-1)) to maximal velocity (m•s(-1)). The quadratic function of two variables that modeled the searched relationship explained 74% of measured values in the acceleration phase and 75% of measured values from the entire extent of the positive power movement in the lift. The optimal load for reaching maximum power output suitable for the dynamics effort strength training was 40% of one repetition maximum, while the optimal mean velocity would be 75% of maximal velocity. Moreover, four zones: maximum power, maximum velocity, velocity-power and strength-power were determined on the basis of the regression function.

Using Maximal Isometric Force to Determine the Optimal Load for Measuring Dynamic Muscle Power

Science.gov (United States)

Spiering, Barry A.; Lee, Stuart M. C.; Mulavara, Ajitkumar P.; Bentley, Jason R.; Nash, Roxanne E.; Sinka, Joseph; Bloomberg, Jacob J.

2009-01-01

Maximal power output occurs when subjects perform ballistic exercises using loads of 30-50% of one-repetition maximum (1-RM). However, performing 1-RM testing prior to power measurement requires considerable time, especially when testing involves multiple exercises. Maximal isometric force (MIF), which requires substantially less time to measure than 1-RM, might be an acceptable alternative for determining the optimal load for power testing. PURPOSE: To determine the optimal load based on MIF for maximizing dynamic power output during leg press and bench press exercises. METHODS: Twenty healthy volunteers (12 men and 8 women; mean +/- SD age: 31+/-6 y; body mass: 72 +/- 15 kg) performed isometric leg press and bench press movements, during which MIF was measured using force plates. Subsequently, subjects performed ballistic leg press and bench press exercises using loads corresponding to 20%, 30%, 40%, 50%, and 60% of MIF presented in randomized order. Maximal instantaneous power was calculated during the ballistic exercise tests using force plates and position transducers. Repeated-measures ANOVA and Fisher LSD post hoc tests were used to determine the load(s) that elicited maximal power output. RESULTS: For the leg press power test, six subjects were unable to be tested at 20% and 30% MIF because these loads were less than the lightest possible load (i.e., the weight of the unloaded leg press sled assembly [31.4 kg]). For the bench press power test, five subjects were unable to be tested at 20% MIF because these loads were less than the weight of the unloaded aluminum bar (i.e., 11.4 kg). Therefore, these loads were excluded from analysis. A trend (p = 0.07) for a main effect of load existed for the leg press exercise, indicating that the 40% MIF load tended to elicit greater power output than the 60% MIF load (effect size = 0.38). A significant (p . 0.05) main effect of load existed for the bench press exercise; post hoc analysis indicated that the effect of

Glycol-Substitute for High Power RF Water Loads

CERN Document Server

Ebert, Michael

2005-01-01

In water loads for high power rf applications, power is dissipated directly into the coolant. Loads for frequencies below approx. 1GHz are ordinarily using an ethylene glycol-water mixture as coolant. The rf systems at DESY utilize about 100 glycol water loads with powers ranging up to 600kW. Due to the increased ecological awareness, the use of glycol is now considered to be problematic. In EU it is forbidden to discharge glycol into the waste water system. In case of cooling system leakages one has to make sure that no glycol is lost. Since it is nearly impossible to avoid any glycol loss in large rf systems, a glycol-substitute was searched for and found. The found sodium-molybdate based substitute is actually a additive for corrosion protection in water systems. Sodium-molybdate is ecologically harmless; for instance, it is also used as fertilizer in agriculture. A homoeopathic dose of 0.4% mixed into deionised water gives better rf absorption characteristics than a 30% glycol mixture. The rf coolant feat...

Concentrating Solar Power Projects - Khi Solar One | Concentrating Solar

Science.gov (United States)

Power | NREL Khi Solar One This page provides information on Khi Solar One, a concentrating solar power (CSP) project, with data organized by background, parcipants and power plant configuration . Status Date: February 8, 2016 Project Overview Project Name: Khi Solar One Country: South Africa Location

The acute effects of moderately loaded concentric-only quarter squats on vertical jump performance.

Science.gov (United States)

Crum, Aaron J; Kawamori, Naoki; Stone, Michael H; Haff, G Gregory

2012-04-01

Limited research exists examining the effect of moderately loaded conditioning activities that are employed as part of a strength-power potentiating complex (SPPC). Additionally, no studies to date have explored the effects of using a concentric-only quarter back squat protocol as part of an SPPC. Therefore, the purpose of this study was to examine the effects of a moderately loaded (50-65% of 1RM) concentric-only quarter back squat protocol on the occurrence of potentiation effects at various time points. Twenty men who could quarter back squat a minimum of 2.4 times their body mass (3.7 ± 0.7 kg·per body mass) participated in this investigation. All subjects participated in 3 conditions: control (CT), a 50% of 1RM trial (50POT), and a 65% of 1RM trial (65POT). One minute before each condition, a maximal countermovement vertical jump (CMJ) was performed. One minute later, the subject performed 1 of 3 conditions: CT condition, 50POT, or 65POT, followed by vertical jumps at 0.5, 3, 5, 10, and 15 minutes after conditioning activity. A force plate was used to quantify displacement, peak power output, peak force, and the rate of force development for each CMJ. There were no significant differences (p > 0.05) in any of the performance measures quantified during the CMJ trials when comparing the CT, 50POT, and 65POT treatment conditions. However, 48% of the subjects demonstrated some degree of potentiation at the 30 seconds after completing the 65POT trial, but this percent increase was not statistically significant. From a practical perspective, if the goal of the SPPC is to create a maximization of the potentiation effect, moderately loaded activities may not be the best alternative.

Load Flow Analysis of Hybrid AC-DC Power System with Offshore Wind Power

DEFF Research Database (Denmark)

Dhua, Debasish; Huang, Shaojun; Wu, Qiuwei

2017-01-01

The offshore wind power has received immense attention because of higher wind speed and lower opposition for construction. A wide range of combinations of high-voltage ACDC transmission have been proposed for integrating offshore wind farms and long-distance power transmission. This paper...... is to model such hybrid AC-DC systems including the interfacing converters, which have several control parameters that can change the load flow of the hybrid systems. Then, the paper proposes a Load Flow algorithm based on the Newton-Raphson method, which covers three different section types...

Concentrating Solar Power Projects - Nevada Solar One | Concentrating Solar

Science.gov (United States)

Power | NREL Nevada Solar One This page provides information on Nevada Solar One, a concentrating solar power (CSP) project, with data organized by background, participants, and power plant configuration. Acciona Energy's Nevada Solar One is the third largest CSP plant in the world and the first plant

Experience of load following in French nuclear power plants

International Nuclear Information System (INIS)

Miossec, C.

1989-01-01

The relative importance of the French nuclear programme has reached such a scale that nuclear power stations can no longer be operated in the base load mode: their capacity exceeded the network demands for 1200 hours in 1983 and it is estimated that this figure will move to 5200 hours in 1990; their power should be able to vary flexibly. These figures illustrate the policy of substituting nuclear power plants for fossil-fired plants and explain the need for nuclear units to provide a quality of service at least equal to that of their ''elders'', which, for several years, have regularly participated in load following. Electricite de France (EDF) therefore had to perform the studies and work necessary to provide nuclear units with the required modulation capacity. There are several grid requirements and three types of flexibility are to be distinguished. The first, load follow, is fundamental when adapting to demand. The second type of flexibility, frequency adjustment, is another important factor in the quality of the product delivered to the consumer. The third type of flexibility is participation in the spinning reserve. When automatic operations are inadequate, available power reserves must be used to support the gird. Load following operations are performed. The operating mode with load modulation is subject to authorisations issued by the governmental organisations responsible for nuclear safety. EDF and the manufacturers have had to prove that such operations remain compatible with safety under normal operating conditions and, in the event of incidents, modulation should be capable of considerably modifying the initial conditions. (5 figures). (Author)

A methodology for Electric Power Load Forecasting

Directory of Open Access Journals (Sweden)

Eisa Almeshaiei

2011-06-01

Full Text Available Electricity demand forecasting is a central and integral process for planning periodical operations and facility expansion in the electricity sector. Demand pattern is almost very complex due to the deregulation of energy markets. Therefore, finding an appropriate forecasting model for a specific electricity network is not an easy task. Although many forecasting methods were developed, none can be generalized for all demand patterns. Therefore, this paper presents a pragmatic methodology that can be used as a guide to construct Electric Power Load Forecasting models. This methodology is mainly based on decomposition and segmentation of the load time series. Several statistical analyses are involved to study the load features and forecasting precision such as moving average and probability plots of load noise. Real daily load data from Kuwaiti electric network are used as a case study. Some results are reported to guide forecasting future needs of this network.

Minimization of Load Variance in Power Grids—Investigation on Optimal Vehicle-to-Grid Scheduling

Directory of Open Access Journals (Sweden)

Kang Miao Tan

2017-11-01

Full Text Available The introduction of electric vehicles into the transportation sector helps reduce global warming and carbon emissions. The interaction between electric vehicles and the power grid has spurred the emergence of a smart grid technology, denoted as vehicle-to grid-technology. Vehicle-to-grid technology manages the energy exchange between a large fleet of electric vehicles and the power grid to accomplish shared advantages for the vehicle owners and the power utility. This paper presents an optimal scheduling of vehicle-to-grid using the genetic algorithm to minimize the power grid load variance. This is achieved by allowing electric vehicles charging (grid-to-vehicle whenever the actual power grid loading is lower than the target loading, while conducting electric vehicle discharging (vehicle-to-grid whenever the actual power grid loading is higher than the target loading. The vehicle-to-grid optimization algorithm is implemented and tested in MATLAB software (R2013a, MathWorks, Natick, MA, USA. The performance of the optimization algorithm depends heavily on the setting of the target load, power grid load and capability of the grid-connected electric vehicles. Hence, the performance of the proposed algorithm under various target load and electric vehicles’ state of charge selections were analysed. The effectiveness of the vehicle-to-grid scheduling to implement the appropriate peak load shaving and load levelling services for the grid load variance minimization is verified under various simulation investigations. This research proposal also recommends an appropriate setting for the power utility in terms of the selection of the target load based on the electric vehicle historical data.

Effect of loading on peak power of the bar, body, and system during power cleans, squats, and jump squats.

Science.gov (United States)

McBride, Jeffrey M; Haines, Tracie L; Kirby, Tyler J

2011-08-01

Nine males (age 24.7 ± 2.1 years, height 175.3 ± 5.5 cm, body mass 80.8 ± 7.2 kg, power clean 1-RM 97.1 ± 6.36 kg, squat 1-RM = 138.3 ± 20.9 kg) participated in this study. On day 1, the participants performed a one-repetition maximum (1-RM) in the power clean and the squat. On days 2, 3, and 4, participants performed the power clean, squat or jump squat. Loading for the power clean ranged from 30% to 90% of the participant's power clean 1-RM and loading for the squat and jump squat ranged from 0% to 90% of the participant's squat 1-RM, all at 10% increments. Peak force, velocity, and power were calculated for the bar, body, and system (bar + body) for all power clean, squat, and jump squat trials. Results indicate that peak power for the bar, body, and system is differentially affected by load and movement pattern. When using the power clean, squat or jump squat for training, the optimal load in each exercise may vary. Throwing athletes or weightlifters may be most concerned with bar power, but jumpers or sprinters may be more concerned with body or system power. Thus, the exercise type and load vary according to the desired stimulus.

Load allocation of power plant using multi echelon economic dispatch

Science.gov (United States)

Wahyuda, Santosa, Budi; Rusdiansyah, Ahmad

2017-11-01

In this paper, the allocation of power plant load which is usually done with a single echelon as in the load flow calculation, is expanded into a multi echelon. A plant load allocation model based on the integration of economic dispatch and multi-echelon problem is proposed. The resulting model is called as Single Objective Multi Echelon Economic Dispatch (SOME ED). This model allows the distribution of electrical power in more detail in the transmission and distribution substations along the existing network. Considering the interconnection system where the distance between the plant and the load center is usually far away, therefore the loss in this model is seen as a function of distance. The advantages of this model is its capability of allocating electrical loads properly, as well as economic dispatch information with the flexibility of electric power system as a result of using multi-echelon. In this model, the flexibility can be viewed from two sides, namely the supply and demand sides, so that the security of the power system is maintained. The model was tested on a small artificial data. The results demonstrated a good performance. It is still very open to further develop the model considering the integration with renewable energy, multi-objective with environmental issues and applied to the case with a larger scale.

Velocity- and power-load relationships of the bench pull vs. bench press exercises.

Science.gov (United States)

Sánchez-Medina, L; González-Badillo, J J; Pérez, C E; Pallarés, J G

2014-03-01

This study compared the velocity- and power-load relationships of the antagonistic upper-body exercises of prone bench pull (PBP) and bench press (BP). 75 resistance-trained athletes performed a progressive loading test in each exercise up to the one-repetition maximum (1RM) in random order. Velocity and power output across the 30-100% 1RM were significantly higher for PBP, whereas 1RM strength was greater for BP. A very close relationship was observed between relative load and mean propulsive velocity for both BP (R2=0.97) and PBP (R2=0.94) which enables us to estimate %1RM from velocity using the obtained prediction equations. Important differences in the load that maximizes power output (Pmax) and the power profiles of both exercises were found according to the outcome variable used: mean (MP), peak (PP) or mean propulsive power (MPP). When MP was considered, the Pmax load was higher (56% BP, 70% PBP) than when PP (37% BP, 41% PBP) or MPP (37% BP, 46% PBP) were used. For each variable there was a broad range of loads at which power output was not significantly different. The differing velocity- and power-load relationships between PBP and BP seem attributable to the distinct muscle architecture and moment arm levers involved in these exercises. © Georg Thieme Verlag KG Stuttgart · New York.

Load-Sharing Characteristics of Power-Split Transmission System Based on Deformation Compatibility and Loaded Tooth Contact Analysis

Directory of Open Access Journals (Sweden)

Hao Dong

2015-01-01

Full Text Available In order to implement the uniform load distribution of the power-split transmission system, a pseudostatic model is built. Based on the loaded tooth contact analysis (LTCA technique, the actual meshing process of each gear pair is simulated and the fitting curve of time-varying mesh stiffness is obtained. And then, the torsional angle deformation compatibility conditions are proposed according to the closed-loop characteristic of power flow, which will be combined with the torque equilibrium conditions and elastic support conditions to calculate the transfer torque of each gear pair. Finally, the load-sharing coefficient of the power-split transmission system is obtained, and the influences of the installation errors are analyzed. The results show that the above-mentioned installation errors comprehensively influence the load-sharing characteristics, and the reduction of only one error could not effectively achieve perfect load-sharing characteristics. Allowing for the spline clearance floating and constrained by the radial spacing ring, the influence of the floating pinion is analyzed. It shows that the floating pinion can improve the load-sharing characteristics. Through the comparison between the theoretical and related experimental data, the reasonability and feasibility of the above-proposed method and model are verified.

The Determination of Load Profiles and Power Consumptions of Home Appliances

Directory of Open Access Journals (Sweden)

Fatih Issi

2018-03-01

Full Text Available In recent years, the increment of distributed electricity generation based on renewable energy sources and improvement of communication technologies have caused the development of next-generation power grids known as smart grids. The structures of smart grids have bidirectional communication capability and enable the connection of energy generated from distributed sources to any point on the grid. They also support consumers in energy efficiency by creating opportunities for management of power consumption. The information on power consumption and load profiles of home appliances is essential to perform load management in the dwelling accurately. In this study, the power consumption data for all the basic home appliances, utilized in a two-person family in Çankırı, Turkey, was obtained with high resolution in one-second intervals. The detailed power consumption analysis and load profile were executed for each home appliance. The obtained data is not only the average power consumption of each appliance but also characterizes different operating modes or their cycles. In addition, the impact of these devices on home energy management studies and their standby power consumptions were also discussed. The acquired data is an important source to determine the load profile of individual home appliances precisely in home energy management studies. Although the results of this study do not completely reflect the energy consumption behavior of the people who live in this region, they can reveal the trends in load demands based on a real sample and customer consumption behavior of a typical two-person family.

Minimum load reduction for once-through boiler power plants

International Nuclear Information System (INIS)

Colombo, P.; Godina, G.; Manganelli, R.

2001-01-01

In Italy the liberalization process of energy market is giving particular importance to the optimization of power plants performances; especially for those that will be called to satisfy grid peak demands. On those plants some techniques have been experimented for the reduction of minimum load; these techniques, investigated and tested by an engineering dynamic simulator, have been sequentially tested on plant. The minimum load for up 320 MW of Tavazzano power plants has been diminished from 140 down to 80 MW without plant modification [it

The effects of low and moderate doses of caffeine supplementation on upper and lower body maximal voluntary concentric and eccentric muscle force.

Science.gov (United States)

Tallis, Jason; Yavuz, Harley C M

2018-03-01

Despite the growing quantity of literature exploring the effect of caffeine on muscular strength, there is a dearth of data that directly explores differences in erogenicity between upper and lower body musculature and the dose-response effect. The present study sought to investigate the effects of low and moderate doses of caffeine on the maximal voluntary strength of the elbow flexors and knee extensors. Ten nonspecifically strength-trained, recreationally active participants (aged 21 ± 0.3 years) completed the study. Using a randomised, counterbalanced, and double-blind approach, isokinetic concentric and eccentric strength was measured at 60 and 180°/s following administration of a placebo, 3 mg·kg -1 body mass caffeine, and 6 mg·kg -1 body mass caffeine. There was no effect of caffeine on the maximal voluntary concentric and eccentric strength of the elbow flexors, or the eccentric strength of the knee extensors. Both 3 and 6 mg·kg -1 body mass caffeine caused a significant increase in peak concentric force of the knee extensors at 180°/s. No difference was apparent between the 2 concentrations. Only 6 mg·kg -1 body mass caused an increase in peak concentric force during repeated contractions. The results infer that the effective caffeine concentration to evoke improved muscle performance may be related to muscle mass and contraction type. The present work indicates that a relatively low dose of caffeine treatment may be effective for improving lower body muscular strength, but may have little benefit for the strength of major muscular groups of the upper body.

Load shedding and emergency load sequencing system at Sizewell B power station

International Nuclear Information System (INIS)

Bowcock, S.; Miller, D.

1992-01-01

Sizewell B Nuclear Power Station has a main electrical system that connects together the main turbo-generators, generating at 23.5kV, the 400kV grid and the auxiliary equipment required to operate the station. A separate essential electrical system fed from the main electrical system, supplies all the auxiliaries required to shut-down the nuclear reactor and maintain it in a safe shut-down condition. For safety reasons four similar independent essential electrical systems are provided, each headed by a 3.3kV switchboard and a stand-by 8MW diesel generator. Feeds from the 3.3kV switchboards in turn supply the essential 3.3kV drives and transformer fed 415V essential switchboards. The function of the Load Shedding and Emergency Load Sequencing (LSELS) System is to monitor the condition of the 3.3kV incoming supply from the main electrical system to each essential 3.3kV switchboard and initiate its replacement, with the supply from the associated diesel generator, if it is outside set parameters. In order to achieve this transfer the essential electrical system load must be reduced to a level which the diesel can accommodate as a standing load and then allow the sequenced reconnection of required loads so as not to overload the diesel. The LSELS equipment is categorised as Safety Category 1E and has a significant importance to the safe operation of the power station. Therefore the design of the system must be highly reliable and the purpose of this paper is to detail the design approach used to ensure that a high system reliability is achieved. (Author)

Power training using pneumatic machines vs. plate-loaded machines to improve muscle power in older adults.

Science.gov (United States)

Balachandran, Anoop T; Gandia, Kristine; Jacobs, Kevin A; Streiner, David L; Eltoukhy, Moataz; Signorile, Joseph F

2017-11-01

Power training has been shown to be more effective than conventional resistance training for improving physical function in older adults; however, most trials have used pneumatic machines during training. Considering that the general public typically has access to plate-loaded machines, the effectiveness and safety of power training using plate-loaded machines compared to pneumatic machines is an important consideration. The purpose of this investigation was to compare the effects of high-velocity training using pneumatic machines (Pn) versus standard plate-loaded machines (PL). Independently-living older adults, 60years or older were randomized into two groups: pneumatic machine (Pn, n=19) and plate-loaded machine (PL, n=17). After 12weeks of high-velocity training twice per week, groups were analyzed using an intention-to-treat approach. Primary outcomes were lower body power measured using a linear transducer and upper body power using medicine ball throw. Secondary outcomes included lower and upper body muscle muscle strength, the Physical Performance Battery (PPB), gallon jug test, the timed up-and-go test, and self-reported function using the Patient Reported Outcomes Measurement Information System (PROMIS) and an online video questionnaire. Outcome assessors were blinded to group membership. Lower body power significantly improved in both groups (Pn: 19%, PL: 31%), with no significant difference between the groups (Cohen's d=0.4, 95% CI (-1.1, 0.3)). Upper body power significantly improved only in the PL group, but showed no significant difference between the groups (Pn: 3%, PL: 6%). For balance, there was a significant difference between the groups favoring the Pn group (d=0.7, 95% CI (0.1, 1.4)); however, there were no statistically significant differences between groups for PPB, gallon jug transfer, muscle muscle strength, timed up-and-go or self-reported function. No serious adverse events were reported in either of the groups. Pneumatic and plate-loaded

Measurements and modelling of base station power consumption under real traffic loads.

Science.gov (United States)

Lorincz, Josip; Garma, Tonko; Petrovic, Goran

2012-01-01

Base stations represent the main contributor to the energy consumption of a mobile cellular network. Since traffic load in mobile networks significantly varies during a working or weekend day, it is important to quantify the influence of these variations on the base station power consumption. Therefore, this paper investigates changes in the instantaneous power consumption of GSM (Global System for Mobile Communications) and UMTS (Universal Mobile Telecommunications System) base stations according to their respective traffic load. The real data in terms of the power consumption and traffic load have been obtained from continuous measurements performed on a fully operated base station site. Measurements show the existence of a direct relationship between base station traffic load and power consumption. According to this relationship, we develop a linear power consumption model for base stations of both technologies. This paper also gives an overview of the most important concepts which are being proposed to make cellular networks more energy-efficient.

Measurements and Modelling of Base Station Power Consumption under Real Traffic Loads

Directory of Open Access Journals (Sweden)

Goran Petrovic

2012-03-01

Full Text Available Base stations represent the main contributor to the energy consumption of a mobile cellular network. Since traffic load in mobile networks significantly varies during a working or weekend day, it is important to quantify the influence of these variations on the base station power consumption. Therefore, this paper investigates changes in the instantaneous power consumption of GSM (Global System for Mobile Communications and UMTS (Universal Mobile Telecommunications System base stations according to their respective traffic load. The real data in terms of the power consumption and traffic load have been obtained from continuous measurements performed on a fully operated base station site. Measurements show the existence of a direct relationship between base station traffic load and power consumption. According to this relationship, we develop a linear power consumption model for base stations of both technologies. This paper also gives an overview of the most important concepts which are being proposed to make cellular networks more energy-efficient.

Analysis and comparison between a concentrating solar and a photovoltaic power plant

International Nuclear Information System (INIS)

Desideri, Umberto; Campana, Pietro Elia

2014-01-01

Highlights: • The performance of CSP and PV plants were compared with similar assumptions. • The influence of the site on the performance of CSP and PV plants is determined. • CSP plants performance is always higher in locations where DNI is prevailing. • CSP levelized electricity costs are generally lower than those from PV plants. • PV plants may produce larger amounts of electricity where the DNI is not prevailing. - Abstract: Solar energy is a source, which can be exploited in two main ways to generate power: direct conversion into electric energy using photovoltaic panels and by means of a thermodynamic cycle. In both cases the amount of energy, which can be converted, is changing daily and seasonally, causing a discontinuous electricity production. In order to limit this drawback, concentrated solar power plants (CSP) and photovoltaic plants (PV) can be equipped with a storage system that can be configured not only for covering peak-loads but also for the base-load after the sunset or before the sunrise. In CSP plants it is the sun’s thermal energy to be stored, whereas in PV applications it is the electrical energy to be stored in batteries, although this is not economically and environmentally feasible in large-scale power plants. The main aim of this paper is to study the performance of concentrated solar power plants equipped with molten salts thermal storage to cover a base load of 3 MW el . In order to verify the possibility of storing effectively the thermal energy and to design a plant for base load operation, two locations were chosen for the study: Gela in southern Italy, and Luxor in Egypt. The electricity production of the CSP facilities has been analyzed and then compared with the electricity production of PV plants. Two different comparisons were done, one by sizing the PV plant to provide the same peak power and one using the same collectors surface. This paper has also highlighted some important issues in site selection and in

On load flow control in electric power systems

Energy Technology Data Exchange (ETDEWEB)

Herbig, Arnim

2000-01-01

This dissertation deals with the control of active power flow, or load flow in electric power systems. During the last few years, interest in the possibilities to control the active power flows in transmission systems has increased significantly. There is a number of reasons for this, coming both from the application side - that is, from power system operations - and from the technological side. where advances in power electronics and related technologies have made new system components available. Load flow control is by nature a multi-input multi-output problem, since any change of load flow in one line will be complemented by changes in other lines. Strong cross-coupling between controllable components is to be expected, and the possibility of adverse interactions between these components cannot be rejected straightaway. Interactions with dynamic phenomena in the power system are also a source of concern. Three controllable components are investigated in this thesis, namely the controlled series capacitor (CSC), the phase angle regulator (PAR), and the unified power flow controller (UPFC). Properties and characteristics of these devices axe investigated and discussed. A simple control strategy is proposed. This strategy is then analyzed extensively. Mathematical methods and physical knowledge about the pertinent phenomena are combined, and it is shown that this control strategy can be used for a fairly general class of devices. Computer simulations of the controlled system provide insight into the system behavior in a system of reasonable size. The robustness and stability of the control system are discussed as are its limits. Further, the behavior of the control strategy in a system where the modeling allows for dynamic phenomena are investigated with computer simulations. It is discussed under which circumstances the control action has beneficial or detrimental effect on the system dynamics. Finally, a graphical approach for analyzing the effect of controllers

Low reflectance high power RF load

Science.gov (United States)

Ives, R. Lawrence; Mizuhara, Yosuke M.

2016-02-02

A load for traveling microwave energy has an absorptive volume defined by cylindrical body enclosed by a first end cap and a second end cap. The first end cap has an aperture for the passage of an input waveguide with a rotating part that is coupled to a reflective mirror. The inner surfaces of the absorptive volume consist of a resistive material or are coated with a coating which absorbs a fraction of incident RF energy, and the remainder of the RF energy reflects. The angle of the reflector and end caps is selected such that reflected RF energy dissipates an increasing percentage of the remaining RF energy at each reflection, and the reflected RF energy which returns to the rotating mirror is directed to the back surface of the rotating reflector, and is not coupled to the input waveguide. Additionally, the reflector may have a surface which generates a more uniform power distribution function axially and laterally, to increase the power handling capability of the RF load. The input waveguide may be corrugated for HE11 mode input energy.

A Wind Farm Controller for Load and Power Optimization in a Farm

DEFF Research Database (Denmark)

Soleimanzadeh, Maryam; Brand, Arno; Wisniewski, Rafal

2011-01-01

This paper describes the design procedure of an optimal wind farm controller. The controller optimizes the structural load and power production simultaneously, on the basis of an analytical wind farm model. The farm model delivers maps of wind, loads and energy in the wind farm. Moreover, the model...... computes the wind speed at the turbines, turbine bending moments and aerodynamic power and torque. The optimal control problem is formulated based on the model for two different wind directions. The controller determines the reference signals for each individual wind turbine controller in two scenarios...... based on low and high wind speed. In low wind speed, the reference signals for rotor speed are adjusted, taking the trade-off between power maximization and load minimization into account. In high wind speed, the power and pitch angle reference signals are determined while structural loads are minimized....

Power law load dependence of atomic friction

OpenAIRE

Fusco, C.; Fasolino, A.

2004-01-01

We present a theoretical study of the dynamics of a tip scanning a graphite surface as a function of the applied load. From the analysis of the lateral forces, we extract the friction force and the corrugation of the effective tip-surface interaction potential. We find both the friction force and potential amplitude to have a power-law dependence on applied load with exponent similar to1.6. We interpret these results as characteristic of sharp undeformable tips in contrast to the case of macr...

Optimal Load Response to Time-of-Use Power Price for Demand Side Management in Denmark

DEFF Research Database (Denmark)

Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte

2010-01-01

-of-use power price for demand side management in order to save the energy costs as much as possible. 3 typical different kinds of loads (industrial load, residential load and commercial load) in Denmark are chosen as study cases. The energy costs decrease up to 9.6% with optimal load response to time......-of-use power price for different loads. Simulation results show that the optimal load response to time-of-use power price for demand side management generates different load profiles and reduces the load peaks. This kind of load patterns may also have significant effects on the power system normal operation.......Since the hourly spot market price is available one day ahead in Denmark, the price could be transferred to the consumers and they may shift their loads from high price periods to the low price periods in order to save their energy costs. This paper presents a load optimization method to time...

Rest Interval Required for Power Training With Power Load in the Bench Press Throw Exercise.

Science.gov (United States)

Hernández Davó, Jose L; Solana, Rafael Sabido; Sarabia Marín, Jose M; Fernández Fernández, Jaime; Moya Ramón, Manuel

2016-05-01

This study aimed to test the influence of various rest interval (RI) durations used between sets on power output performance and physiological and perceptual variables during a strength training session using 40% of the 1 repetition maximum (1RM) in the bench press throw exercise. Thirty-one college students (18 males and 13 females) took part in the study. The experimental protocol consists of 5 sets of 8 repetitions of the bench press throw exercise with a load representing 40% of 1RM. Subjects performed the experimental protocol on 3 different occasions, differing by the RI between sets (1, 2, or 3 minutes). During the sessions, power data (mean power and peak power), physiological (lactate concentration [La]) and perceptual (rating of perceived exertion) variables were measured. In addition, delayed onset muscular soreness was reported 24 and 48 hours after the training session. One-way repeated-measures analysis of variance showed that 1-minute RI entailed higher power decreases and greater increases in values of physiological and perceptual variables compared with both 2- and 3-minute RIs. Nevertheless, no differences were found between 2- and 3-minute RIs. Therefore, this study showed that, when training with 40% of 1RM in the bench press throw exercise, a 2-minute RI between sets can be enough to avoid significant decreases in power output. Consequently, training sessions' duration could be reduced without causing excessive fatigue, allowing additional time to focus on other conditioning priorities.

An AC/AC Direct Power Conversion Topology Having Multiple Power Grid Connections with Adjustable Loading

DEFF Research Database (Denmark)

Klumpner, Christian; Blaabjerg, Frede

2004-01-01

independent producers/consumers to connect to multiple distribution grids in order to optimise the electricity price, as this will vary during the day from one power distribution company to another one. It will be needed to have a load that can smoothly adjust the power consumed from each power grid in order......Normally, a power converter has one supply port to connect to the power grid and one or multiple output ports to connect to AC loads that require variable voltage and variable frequency. As the trend on the energy market is towards deregulation, new converter topologies are needed to allow...... to minimize the overall energy cost or in case of special applications, to improve the system redundancy. Also, having a generator that can simultaneously feed fractions of its power into multiple grids which are not coupled (different voltage, frequency, displacement angle) and continuously adjust...

High power RF performance test of an improved SiC load

Energy Technology Data Exchange (ETDEWEB)

Hwang, W.H.; Kim, S.H.; Park, Y.J. [Pohang Accelerator Lab., Pohang Inst. of Sceince and Technology, Pohang (KR)] [and others

1998-11-01

Two prototypes of SiC loads sustaining a maximum peak power of 50 MW were fabricated by Nihon Koshuha Co. in Japan. The PAL conducted the high power RF performance tests of SiC loads to verify the operation characteristics for the application to the PLS Linac. The in-situ facility for the K 12 module was used for the test, which consists of a modulator and klystron system, waveguide network, vacuum and cooling system, and RF analyzing equipment. As the test results, no breakdown appeared up to 50 MW peak power of 1 {mu}s pulse width at a repetition rate of 50 Hz. However, as the peak power increased above 20 MW at 4 {mu}s with 10 Hz, the breakdown phenomena has been observed. Analysing the test results with the current operation power level of PLS Linac, it is confirmed that the SiC loads well satisfy the criteria of the PLS Linac operation. (author)

Local load management system and intermittent power on the grid

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-07-01

The project relates to the UK's obligations on renewable energy sources. The objectives were (i) to identify contractual requirements and commercial benefits of load management under the UK's Renewable Obligation and electric power trading arrangements (ii) through modelling, demonstrate the benefits of load management to major customers operating on-site wind generators; (iii) to develop a low-cost load management system incorporating communication technologies and switching devices and (iv) to identify the social and psychological aspects of load management. The demonstration of the load management system was conducted on the Findhorn Foundation's low voltage electric power distribution network and a 75kw wind turbine. The project demonstrated suitable technology for distributed load management on a grid-connected system in order to optimize the renewable energy generated on site, and the analyses identified several areas where grid-connected management can provide financial benefits. There is much scope for exploitation of commercial opportunities. The work was conducted by Econnect Ltd under contract to the DTI.

Study of Flexible Load Dispatch to Improve the Capacity of Wind Power Absorption

Science.gov (United States)

Yunlei, Yang; Shifeng, Zhang; Xiao, Chang; Da, Lei; Min, Zhang; Jinhao, Wang; Shengwen, Li; Huipeng, Li

2017-05-01

The dispatch method which track the trend of load demand by arranging the generation scheme of controllable hydro or thermal units faces great difficulties and challenges. With the increase of renewable energy sources such as wind power and photovoltaic power introduced to grid, system has to arrange much more spinning reserve units to compensate the unbalanced power. How to exploit the peak-shaving potential of flexible load which can be shifted with time or storage energy has become many scholars’ research direction. However, the modelling of different kinds of load and control strategy is considerably difficult, this paper choose the Air Conditioner with compressor which can storage energy in fact to study. The equivalent thermal parameters of Air Conditioner has been established. And with the use of “loop control” strategies, we can predict the regulated power of Air Conditioner. Then we established the Gen-Load optimal scheduling model including flexible load based on traditional optimal scheduling model. At last, an improved IEEE-30 case is used to verify. The result of simulation shows that flexible load can fast-track renewable power changes. More than that, with flexible load and reasonable incentive method to consumers, the operating cost of the system can be greatly cut down.

Automatic control of load increases power and efficiency in a microbial fuel cell

Energy Technology Data Exchange (ETDEWEB)

Premier, Giuliano C.; Kim, Jung Rae; Michie, Iain [Sustainable Environment Research Centre (SERC), Faculty of Advanced Technology, University of Glamorgan, Pontypridd, Mid-Glamorgan CF37 1DL (United Kingdom); Dinsdale, Richard M.; Guwy, Alan J. [Sustainable Environment Research Centre (SERC), Faculty of Health, Sport and Science, University of Glamorgan, Pontypridd, Mid-Glamorgan CF37 1DL (United Kingdom)

2011-02-15

Increasing power production and coulombic efficiency (CE) of microbial fuel cells (MFCs) is a common research ambition as the viability of the technology depends to some extent on these measures of performance. As MFCs are typically time varying systems, comparative studies of controlled and un-controlled external load impedance are needed to show if control affects the biocatalyst development and hence MFC performance. The application of logic based control of external load resistance is shown to increase the power generated by the MFC, when compared to an equivalent system which has a static resistive load. The controlled MFC generated 1600 {+-} 400 C, compared to 300 {+-} 10 C with an otherwise replicate fixed load MFC system. The use of a parsimonious gradient based control was able to increase the CE to within the range of 15.1-22.7%, while the CE for a 200 {omega} statically loaded MFC lay in the range 3.3-3.7%. The controlled MFC improves the electrogenic anodic biofilm selection for power production, indicating that greater power and substrate conversion can be achieved by controlling load impedance. Load control ensured sustainable current demand, applied microbial selection pressures and provided near-optimal impedance for power transference, compared to the un-controlled system. (author)

A Comparison of Load-Velocity and Load-Power Relationships Between Well-Trained Young and Middle-Aged Males During Three Popular Resistance Exercises.

Science.gov (United States)

Fernandes, John F T; Lamb, Kevin L; Twist, Craig

2018-05-01

Fernandes, JFT, Lamb, KL, and Twist, C. A comparison of load-velocity and load-power relationships between well-trained young and middle-aged males during 3 popular resistance exercises. J Strength Cond Res 32(5): 1440-1447, 2018-This study examined the load-velocity and load-power relationships among 20 young (age 21.0 ± 1.6 years) and 20 middle-aged (age 42.6 ± 6.7 years) resistance-trained males. Participants performed 3 repetitions of bench press, squat, and bent-over-row across a range of loads corresponding to 20-80% of 1 repetition maximum (1RM). Analysis revealed effects (p velocity for all 3 exercises, and interaction effects on power for squat and bent-over-row (p bench press and bent-over-row, the young group produced higher barbell velocities, with the magnitude of the differences decreasing as load increased (ES; effect size 0.0-1.7 and 1.0-2.0, respectively). Squat velocity was higher in the young group than the middle-aged group (ES 1.0-1.7) across all loads, as was power for each exercise (ES 1.0-2.3). For all 3 exercises, both velocity and 1RM were correlated with optimal power in the middle-aged group (r = 0.613-0.825, p velocities at low external loads and power outputs as high as the young males across a range of external resistances. Moreover, the strong correlations between 1RM and velocity with optimal power suggest that middle-aged males would benefit from training methods which maximize these adaptations.

Effects of voluntary and automatic control of center of pressure sway during quiet standing.

Science.gov (United States)

Ueta, Kozo; Okada, Yohei; Nakano, Hideki; Osumi, Michihiro; Morioka, Shu

2015-01-01

The authors investigated the effects of voluntary and automatic control on the spatial variables (envelope area, maximal amplitude, and root mean square [RMS]) of center of pressure (COP) displacement during quiet standing and identified differences in their postural control strategies (mean velocity [MV], mean power frequency [MPF], and power density). COP data were recorded under relaxed (experimental control), still (voluntary control), and dual (automatic control) conditions. RMS was significantly lower in the still and dual conditions than in the relaxed condition. MV, MPF, and power density were significantly higher in the still condition than in the dual condition. These results indicate that both voluntary and automatic control decrease the spatial variables of COP displacement; however, their postural control strategies are different.

Nectar loads as fuel for collecting nectar and pollen in honeybees: adjustment by sugar concentration.

Science.gov (United States)

Harano, Ken-Ichi; Nakamura, Jun

2016-06-01

When honeybee foragers leave the nest, they receive nectar from nest mates for use as fuel for flight or as binding material to build pollen loads. We examined whether the concentration of nectar carried from the nest changes with the need for sugar. We found that pollen foragers had more-concentrated nectar (61.8 %) than nectar foragers (43.8 %). Further analysis revealed that the sugar concentration of the crop load increased significantly with waggle duration, an indicator of food-source distance, in both groups of foragers. Crop volume also increased with waggle duration. The results support our argument that foragers use concentrated nectar when the need for sugar is high and suggest that they precisely adjust the amount of sugar in the crop by altering both volume and nectar concentrations. We also investigated the impact of the area where foragers receive nectar on the crop load concentration at departure. Although nectar and pollen foragers tend to load nectar at different areas in the nest, area did not have a significant effect on crop load concentration. Departing foragers showed an average of 2.2 momentary (nectar with inappropriate concentrations during these contacts.

DC switching regulated power supply for driving an inductive load

Science.gov (United States)

Dyer, George R.

1986-01-01

A power supply for driving an inductive load current from a dc power supply hrough a regulator circuit including a bridge arrangement of diodes and switching transistors controlled by a servo controller which regulates switching in response to the load current to maintain a selected load current. First and second opposite legs of the bridge are formed by first and second parallel-connected transistor arrays, respectively, while the third and fourth legs of the bridge are formed by appropriately connected first and second parallel connected diode arrays, respectively. The regulator may be operated in three "stages" or modes: (1) For current runup in the load, both first and second transistor switch arrays are turned "on" and current is supplied to the load through both transistor arrays. (2) When load current reaches the desired level, the first switch is turned "off", and load current "flywheels" through the second switch array and the fourth leg diode array connecting the second switch array in series with the load. Current is maintained by alternating between modes 1 and 2 at a suitable duty cycle and switching rate set by the controller. (3) Rapid current rundown is accomplished by turning both switch arrays "off", allowing load current to be dumped back into the source through the third and fourth diode arrays connecting the source in series opposition with the load to recover energy from the inductive load. The three operating states are controlled automatically by the controller.

Bifurcation Analysis of a DC-DC Bidirectional Power Converter Operating with Constant Power Loads

Science.gov (United States)

Cristiano, Rony; Pagano, Daniel J.; Benadero, Luis; Ponce, Enrique

Direct current (DC) microgrids (MGs) are an emergent option to satisfy new demands for power quality and integration of renewable resources in electrical distribution systems. This work addresses the large-signal stability analysis of a DC-DC bidirectional converter (DBC) connected to a storage device in an islanding MG. This converter is responsible for controlling the balance of power (load demand and generation) under constant power loads (CPLs). In order to control the DC bus voltage through a DBC, we propose a robust sliding mode control (SMC) based on a washout filter. Dynamical systems techniques are exploited to assess the quality of this switching control strategy. In this sense, a bifurcation analysis is performed to study the nonlinear stability of a reduced model of this system. The appearance of different bifurcations when load parameters and control gains are changed is studied in detail. In the specific case of Teixeira Singularity (TS) bifurcation, some experimental results are provided, confirming the mathematical predictions. Both a deeper insight in the dynamic behavior of the controlled system and valuable design criteria are obtained.

Concentrating Solar Power Projects - KaXu Solar One | Concentrating Solar

Science.gov (United States)

Power | NREL KaXu Solar One This page provides information on KaXu Solar One, a concentrating solar power (CSP) project, with data organized by background, parcipants and power plant configuration . Status Date: April 14, 2015 Project Overview Project Name: KaXu Solar One Country: South Africa Location

Intrusive images and voluntary memory for affective pictures: contextualization and dual-task interference.

Science.gov (United States)

Krans, Julie; Langner, Oliver; Reinecke, Andrea; Pearson, David G

2013-12-01

The present study addressed the role of context information and dual-task interference during the encoding of negative pictures on intrusion development and voluntary recall. Healthy participants were shown negative pictures with or without context information. Pictures were either viewed alone or concurrently with a visuospatial or verbal task. Participants reported their intrusive images of the pictures in a diary. At follow-up, perceptual and contextual memory was tested. Participants in the context group reported more intrusive images and perceptual voluntary memory than participants in the no context group. No effects of the concurrent tasks were found on intrusive image frequency, but perceptual and contextual memory was affected according to the cognitive load of the task. The analogue method cannot be generalized to real-life trauma and the secondary tasks may differ in cognitive load. The findings challenge a dual memory model of PTSD but support an account in which retrieval strategy, rather than encoding processes, accounts for the experience of involuntary versus voluntary recall. Copyright © 2013 Elsevier Ltd. All rights reserved.

Voluntary euthanasia.

Science.gov (United States)

Brewin, Thurstan B

1986-05-10

Brewin comments upon James Rachels' The End of Life (Oxford University Press; 1986) and Voluntary Euthanasia (Peter Owen; 1986), a compilation edited by A.B. Downing and B. Smoker that is an expanded version of a 1969 work by Britain's Voluntary Euthanasia Society. Rachels maintains that it is illogical to distinguish between active and passive euthanasia. In Voluntary Euthanasia, 17 contributors argue the pros and cons of the issue. The Voluntary Euthanasia Society proposes that mentally competent persons be allowed by law to request euthanasia, either when taken ill or by advance directive. Brewin says he is almost but not quite convinced by the arguments for legalized voluntary euthanasia. He is concerned about the "slippery slope," the uncertainties of prognosis and quality of life judgments, the pressures to which the terminally ill or aged might be subjected, and the potentially negative impact of euthanasia on the physician patient relationship.

Load management potentials for the railway power system; Potenziale fuer das Lastmanagement im Bahnenergiesystem

Energy Technology Data Exchange (ETDEWEB)

Bosch, Julius; Aniceto, Josep M. [SBB AG Infrastruktur Energie, Zollikofen (Switzerland)

2013-02-15

The railway power supply system of the Schweizerische Bundesbahnen (SBB) is characterised by major load fluctuations that are expected to increase in the future. The available power that is generated must be kept at absolute load peak level which causes high costs. Simulations show that a load management is a practicable way of noticeably reducing load peaks in the SBB railway power supply system without having an adverse effect on railway operations or the energy demand.

Voluntary resistance running induces increased hippocampal neurogenesis in rats comparable to load-free running.

Science.gov (United States)

Lee, Min Chul; Inoue, Koshiro; Okamoto, Masahiro; Liu, Yu Fan; Matsui, Takashi; Yook, Jang Soo; Soya, Hideaki

2013-03-14

Recently, we reported that voluntary resistance wheel running with a resistance of 30% of body weight (RWR), which produces shorter distances but higher work levels, enhances spatial memory associated with hippocampal brain-derived neurotrophic factor (BDNF) signaling compared to wheel running without a load (WR) [17]. We thus hypothesized that RWR promotes adult hippocampal neurogenesis (AHN) as a neuronal substrate underlying this memory improvement. Here we used 10-week-old male Wistar rats divided randomly into sedentary (Sed), WR, and RWR groups. All rats were injected intraperitoneally with the thymidine analogue 5-Bromo-2'-deoxuridine (BrdU) for 3 consecutive days before wheel running. We found that even when the average running distance decreased by about half, the average work levels significantly increased in the RWR group, which caused muscular adaptation (oxidative capacity) for fast-twitch plantaris muscle without causing any negative stress effects. Additionally, immunohistochemistry revealed that the total BrdU-positive cells and newborn mature cells (BrdU/NeuN double-positive) in the dentate gyrus increased in both the WR and RWR groups. These results provide new evidence that RWR has beneficial effects on AHN comparable to WR, even with short running distances. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Canadian House Dust Study: Population-based concentrations, loads and loading rates of arsenic, cadmium, chromium, copper, nickel, lead, and zinc inside urban homes

Energy Technology Data Exchange (ETDEWEB)

Rasmussen, Pat E. [Exposure and Biomonitoring Division, Healthy Environments and Consumer Safety Branch, Health Canada, 50 Colombine Driveway, Ottawa, ON, Canada K1A 0K9 (Canada); Department of Earth Sciences, University of Ottawa, 140 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Levesque, Christine [Exposure and Biomonitoring Division, Healthy Environments and Consumer Safety Branch, Health Canada, 50 Colombine Driveway, Ottawa, ON, Canada K1A 0K9 (Canada); Chénier, Marc; Gardner, H. David [Exposure and Biomonitoring Division, Healthy Environments and Consumer Safety Branch, Health Canada, 50 Colombine Driveway, Ottawa, ON, Canada K1A 0K9 (Canada); Department of Earth Sciences, University of Ottawa, 140 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Jones-Otazo, Heather [Regions and Programs Branch, Health Canada, 180 Queen Street West, Toronto, ON, Canada M5V 3L7 (Canada); Petrovic, Sanya [Contaminated Sites Division, Healthy Environments and Consumer Safety Branch, Health Canada, 269 Laurier Ave West, Ottawa, ON, Canada K1A 0K9 (Canada)

2013-01-15

The Canadian House Dust Study was designed to obtain nationally representative urban house dust metal concentrations (μg g{sup −1}) and metal loadings (μg m{sup −2}) for arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn). Consistent sampling of active dust of known age and provenance (area sampled) also permitted the calculation of indoor loading rates (mg m{sup −2} day{sup −1} for dust and μg m{sup −2} day{sup −1} for metals) for the winter season (from 2007 to 2010) when houses are most tightly sealed. Geomean/median indoor dust loading rates in homes located more than 2 km away from industry of any kind (9.6/9.1 mg m{sup −2} day{sup −1}; n = 580) were significantly lower (p < .001) than geomean (median) dust loading rates in homes located within 2 km of industry (13.5/13.4 mg m{sup −2} day{sup −1}; n = 421). Proximity to industry was characterized by higher indoor metal loading rates (p < .003), but no difference in dust metal concentrations (.29 ≥ p ≤ .97). Comparisons of non-smokers' and smokers' homes in non-industrial zones showed higher metal loading rates (.005 ≥ p ≤ .038) in smokers' homes, but no difference in dust metal concentrations (.15 ≥ p ≤ .97). Relationships between house age and dust metal concentrations were significant for Pb, Cd and Zn (p < .001) but not for the other four metals (.14 ≥ p ≤ .87). All seven metals, however, displayed a significant increase in metal loading rates with house age (p < .001) due to the influence of higher dust loading rates in older homes (p < .001). Relationships between three measures of metals in house dust – concentration, load, and loading rate – in the context of house age, smoking behavior and urban setting consistently show that concentration data is a useful indicator of the presence of metal sources in the home, whereas dust mass is the overriding influence on metal loadings and loading rates

Study on Impact of Electric Vehicles Charging Models on Power Load

Science.gov (United States)

Cheng, Chen; Hui-mei, Yuan

2017-05-01

With the rapid increase in the number of electric vehicles, which will lead the power load on grid increased and have an adversely affect. This paper gives a detailed analysis of the following factors, such as scale of the electric cars, charging mode, initial charging time, initial state of charge, charging power and other factors. Monte Carlo simulation method is used to compare the two charging modes, which are conventional charging and fast charging, and MATLAB is used to model and simulate the electric vehicle charging load. The results show that compared with the conventional charging mode, fast charging mode can meet the requirements of fast charging, but also bring great load to the distribution network which will affect the reliability of power grid.

Short term and medium term power distribution load forecasting by neural networks

International Nuclear Information System (INIS)

Yalcinoz, T.; Eminoglu, U.

2005-01-01

Load forecasting is an important subject for power distribution systems and has been studied from different points of view. In general, load forecasts should be performed over a broad spectrum of time intervals, which could be classified into short term, medium term and long term forecasts. Several research groups have proposed various techniques for either short term load forecasting or medium term load forecasting or long term load forecasting. This paper presents a neural network (NN) model for short term peak load forecasting, short term total load forecasting and medium term monthly load forecasting in power distribution systems. The NN is used to learn the relationships among past, current and future temperatures and loads. The neural network was trained to recognize the peak load of the day, total load of the day and monthly electricity consumption. The suitability of the proposed approach is illustrated through an application to real load shapes from the Turkish Electricity Distribution Corporation (TEDAS) in Nigde. The data represents the daily and monthly electricity consumption in Nigde, Turkey

Design And Modeling An Automated Digsilent Power System For Optimal New Load Locations

Directory of Open Access Journals (Sweden)

Mohamed Saad

2015-08-01

Full Text Available Abstract The electric power utilities seek to take advantage of novel approaches to meet growing energy demand. Utilities are under pressure to evolve their classical topologies to increase the usage of distributed generation. Currently the electrical power engineers in many regions of the world are implementing manual methods to measure power consumption for farther assessment of voltage violation. Such process proved to be time consuming costly and inaccurate. Also demand response is a grid management technique where retail or wholesale customers are requested either electronically or manually to reduce their load. Therefore this paper aims to design and model an automated power system for optimal new load locations using DPL DIgSILENT Programming Language. This study is a diagnostic approach that assists system operator about any voltage violation cases that would happen during adding new load to the grid. The process of identifying the optimal bus bar location involves a complicated calculation of the power consumptions at each load bus As a result the DPL program would consider all the IEEE 30 bus internal networks data then a load flow simulation will be executed. To add the new load to the first bus in the network. Therefore the developed model will simulate the new load at each available bus bar in the network and generate three analytical reports for each case that captures the overunder voltage and the loading elements among the grid.

The Effect of the Number of Sets on Power Output for Different Loads

Science.gov (United States)

Morales-Artacho, Antonio J.; Padial, Paulino; García-Ramos, Amador; Feriche, Belén

2015-01-01

There is much debate concerning the optimal load (OL) for power training. The purpose of this study was to investigate the effect of the number of sets performed for a given load on mean power output (Pmean). Fourteen physically active men performed 3 sets of 3 bench-press repetitions with 30, 40 and 50 kg. The highest mean power value (Pmax) across all loads and Pmean were compared when data were taken from the first set at each absolute load vs. from the best of three sets performed. Pmean increased from the first to the third set (from 5.99 ± 0.81 to 6.16 ± 0.96 W·kg−1, p = 0.017), resulting in a main effect of the set number (p 0.05). Pmax and velocity were significantly affected by the method employed to determine Pmean at each load (p < 0.05). These results show a positive effect of the number of sets per load on Pmean, affecting Pmax, OL and potentially power training prescription. PMID:26240658

The Effect of the Number of Sets on Power Output for Different Loads

Directory of Open Access Journals (Sweden)

Morales-Artacho Antonio J.

2015-06-01

Full Text Available There is much debate concerning the optimal load (OL for power training. The purpose of this study was to investigate the effect of the number of sets performed for a given load on mean power output (Pmean. Fourteen physically active men performed 3 sets of 3 bench-press repetitions with 30, 40 and 50 kg. The highest mean power value (Pmax across all loads and Pmean were compared when data were taken from the first set at each absolute load vs. from the best of three sets performed. Pmean increased from the first to the third set (from 5.99 ± 0.81 to 6.16 ± 0.96 W·kg−1, p = 0.017, resulting in a main effect of the set number (p 0.05. Pmax and velocity were significantly affected by the method employed to determine Pmean at each load (p < 0.05. These results show a positive effect of the number of sets per load on Pmean, affecting Pmax, OL and potentially power training prescription.

Impacts of Ripple Current to the Loading and Lifetime of Power Semiconductor Device

DEFF Research Database (Denmark)

Ma, Ke; Choi, Uimin; Blaabjerg, Frede

2017-01-01

The thermal loading of power electronics devices is determined by many factors and has being a crucial design consideration because it is closely related to the reliability and cost of the converter system. In this paper the impacts of the ripple current to the loss and thermal loading, as well...... as reliability performances of power devices are comprehensively investigated and tested. It is concluded that the amplitude of ripple current may modify the loss and thermal loading of the power devices, especially under the conditions of converter with low power output, and thus the lifetime of devices could...

Concentrating Solar Power. Report April 2009

Energy Technology Data Exchange (ETDEWEB)

Pihl, Erik (Chalmers Univ. of Technology, Enery and Environment, Goeteborg (Sweden))

2009-04-15

Concentrating solar power (CSP) technologies offer ways to utilise solar radiation by concentrating the light. In a concentrated form, the light can be utilised more cost efficiently. It is focused with mirrors or lenses and used either as a heat source in thermal power cycles (thermal CSP) or as a light source for high efficiency photovoltaic cells (concentrating photovoltaics, CPV). All concentrating systems use tracking to follow the movement of the sun, in two or three dimensions, and require direct sunlight (no diffusing clouds). CSP plants are often more complex, component wise than those based on flat PV. The extra cost of complexity is generally more than offset by the larger scales, the less need for expensive materials such as purified silicon and a better fit with the current energy infrastructure. Some thermal CSP plants offer great possibilities to deal with the intermittency of solar energy, as the heat generated can be stored in the form of a heated liquid in large tanks for many hours with little additional cost, and drive the thermal power generation also during cloudy periods or at night. CSP is growing rapidly and can be an important portion of future low-carbon energy systems. A prerequisite is that expected cost reductions are, at least largely, realised. In regions with good solar conditions (Mediterranean countries, US Southwest, Middle East, Australia etc), CSP systems already in the short-term future can satisfy significant shares of the power demand, to decrease CO{sub 2} emissions. Less solar-intensive regions (Northern Europe, much of North America etc) can be supplied with CSP power from solar-rich regions by using long distance power grids, for instance the high voltage DC cables being deployed and developed today

Three-phase Power Flow Calculation of Low Voltage Distribution Network Considering Characteristics of Residents Load

Science.gov (United States)

Wang, Yaping; Lin, Shunjiang; Yang, Zhibin

2017-05-01

In the traditional three-phase power flow calculation of the low voltage distribution network, the load model is described as constant power. Since this model cannot reflect the characteristics of actual loads, the result of the traditional calculation is always different from the actual situation. In this paper, the load model in which dynamic load represented by air conditioners parallel with static load represented by lighting loads is used to describe characteristics of residents load, and the three-phase power flow calculation model is proposed. The power flow calculation model includes the power balance equations of three-phase (A,B,C), the current balance equations of phase 0, and the torque balancing equations of induction motors in air conditioners. And then an alternating iterative algorithm of induction motor torque balance equations with each node balance equations is proposed to solve the three-phase power flow model. This method is applied to an actual low voltage distribution network of residents load, and by the calculation of three different operating states of air conditioners, the result demonstrates the effectiveness of the proposed model and the algorithm.

Progress in excess of power experiments with electrochemical loading of deuterium in palladium

International Nuclear Information System (INIS)

Violante, V.; Moretti, S.; Bertolotti, M.

2006-01-01

A research activity has been carried out, during the last 3 years, in the field of triggering anomalous heat effects in palladium deuteride. An enhancement of the excess of power reproducibility in deuterated palladium was obtained by using He-Ne Laser irradiation during electrochemical loading. A preliminary correlation between excess of energy and 4 He concentration increasing above the background was found. The continuation of the experimental program confirmed that Laser triggering produce an interesting gain of reproducibility. An upgrade of the experimental set-up has been realized. (author)

Small Signal Stability Improvement of Power Systems Using Optimal Load Responses in Competitive Electricity Markets

DEFF Research Database (Denmark)

Hu, Weihao; Su, Chi; Chen, Zhe

2011-01-01

Since the hourly spot market price is available one day ahead in Denmark, the price could be transferred to the consumers and they may shift some of their loads from high price periods to the low price periods in order to save their energy costs. The optimal load response to an electricity price...... price is proposed. A 17-bus power system with high wind power penetrations, which resembles the Eastern Danish power system, is chosen as the study case. Simulation results show that the optimal load response to electricity prices is an effective measure to improve the small signal stability of power...... for demand side management generates different load profiles and may provide an opportunity to improve the small signal stability of power systems with high wind power penetrations. In this paper, the idea of power system small signal stability improvement by using optimal load response to the electricity...

Optimization of Boiler Control to Improve the Load-following Capability of Power-plant Units

DEFF Research Database (Denmark)

Mortensen, J. H.; Mølbak, T.; Andersen, Palle

The capability to perform fast load changes has been an important issue in the power market, and will become increasingly more so due to the incresing commercialisation of the European power market. An optimizing control system for improving the load-following capability of power-plant units has...... tests on a 265 MW coal-fired power-plant unit reveals that the maximum allowable load gradient that can be imposed on the plant, can be increased from 4 MW/min. to 8 MW/min....

Optimization of Boiler Control to Improve the Load-following Capability of Power-plant Units

DEFF Research Database (Denmark)

Mortensen, J. H.; Mølbak, T.; Andersen, Palle

1998-01-01

The capability to perform fast load changes has been an important issue in the power market, and will become increasingly more so due to the incresing commercialisation of the European power market. An optimizing control system for improving the load-following capability of power-plant units has...... tests on a 265 MW coal-fired power-plant unit reveals that the maximum allowable load gradient that can be imposed on the plant, can be increased from 4 MW/min. to 8 MW/min....

Application of Classification Methods for Forecasting Mid-Term Power Load Patterns

Science.gov (United States)

Piao, Minghao; Lee, Heon Gyu; Park, Jin Hyoung; Ryu, Keun Ho

Currently an automated methodology based on data mining techniques is presented for the prediction of customer load patterns in long duration load profiles. The proposed approach in this paper consists of three stages: (i) data preprocessing: noise or outlier is removed and the continuous attribute-valued features are transformed to discrete values, (ii) cluster analysis: k-means clustering is used to create load pattern classes and the representative load profiles for each class and (iii) classification: we evaluated several supervised learning methods in order to select a suitable prediction method. According to the proposed methodology, power load measured from AMR (automatic meter reading) system, as well as customer indexes, were used as inputs for clustering. The output of clustering was the classification of representative load profiles (or classes). In order to evaluate the result of forecasting load patterns, the several classification methods were applied on a set of high voltage customers of the Korea power system and derived class labels from clustering and other features are used as input to produce classifiers. Lastly, the result of our experiments was presented.

Auxiliary System Load Schemes in Large Thermal and Nuclear Power Plants

International Nuclear Information System (INIS)

Kuzle, I.; Bosnjak, D.; Pandzic, H.

2010-01-01

Uninterrupted auxiliary system power supply in large power plants is a key factor for normal operation, transient states, start-ups and shutdowns and particularly during fault conditions. Therefore, there are many challenges in designing the main electrical system as well as the auxiliary systems power supply. Depending upon the type of fuel used and the environmental control system required, a thermal power plant may consume as much as 10% of its total generation for auxiliary power, while a nuclear power plant may require only 4 - 6% auxiliaries. In general, the larger the power generating plant, the higher the voltage selected for the AC auxiliary electric system. Most stations in the 75 to 500 MW range utilize 4,2 kV as the base auxiliary system voltage. Large generating stations 500 - 1000 MW and more use voltage levels of 6,9 kV and more. Some single dedicated loads such as electric driven boiler feed pumps are supplied ba a 13,8 kV bus. While designing the auxiliary electric system, the following areas must be considered: motor starting requirements, voltage regulation requirements, short-circuit duty requirements, economic considerations, reliability and alternate sources. Auxiliary power supply can't be completely generalized and each situation should be studied on its own merits to determine the optimal solution. Naturally, nuclear power plants have more reliability requirements and safety design criteria. Main coolant-pump power supply and continuity of service to other vital loads deserve special attention. This paper presents an overview of some up-to-date power plant auxiliary load system concepts. The main types of auxiliary loads are described and the electric diagrams of the modern auxiliary system supply concepts are given. Various alternative sources of auxiliary electrical supply are considered, the advantages and disadvantages of these are compared and proposals are made for high voltage distribution systems around the thermal and nuclear plant

Remote Area Power Supply (RAPS) load and resource profiles.

Energy Technology Data Exchange (ETDEWEB)

Giles, Lauren (Energetics, Inc., Washington, DC); Skolnik, Edward G. (Energetics, Inc., Washington, DC); Marchionini, Brian (Energetics, Inc., Washington, DC); Fall, Ndeye K. (Energetics, Inc., Washington, DC)

2007-07-01

In 1997, an international team interested in the development of Remote Area Power Supply (RAPS) systems for rural electrification projects around the world was organized by the International Lead Zinc Research Organization (ILZRO) with the support of Sandia National Laboratories (SNL). The team focused on defining load and resource profiles for RAPS systems. They identified single family homes, small communities, and villages as candidates for RAPS applications, and defined several different size/power requirements for each. Based on renewable energy and resource data, the team devised a ''strawman'' series of load profiles. A RAPS system typically consists of a renewable and/or conventional generator, power conversion equipment, and a battery. The purpose of this report is to present data and information on insolation levels and load requirements for ''typical'' homes, small communities, and larger villages around the world in order to facilitate the development of robust design practices for RAPS systems, and especially for the storage battery component. These systems could have significant impact on areas of the world that would otherwise not be served by conventional electrical grids.

Method of bringing nuclear power plant to fractional electrical load conditions

International Nuclear Information System (INIS)

Iljunin, V.G.; Kuznetsoy, I.A.; Murogov, V.M.; Shmelev, A.N.

1978-01-01

A method is described of bringing a nuclear power plant to fractional electric load conditions, which power plant comprises at least two nuclear reactors, at least one nuclear reactor being a breeder and both reactors transferring heat to the turbine working substance, consisting in that the consumption of the turbine working substance is reduced in accordance with a predetermined fractional load. At the same time, the amount of heat being transferred from the nuclear reactors to the turbine working substance is reduced, for which purpose the reactors are included in autonomous cooling circuits to successively transfer heat to the turbine working substance. The breeding reactor is included in the cooling circuit with a lower coolant temperature, the temperature of the coolant at the inlet and outlet of the breeder being reduced to a level ensuring the operation of the nuclear power plant in predetermined fractional load conditions, due to which the power of the breeder is increased, and afterheat is removed

Probability problems in seismic risk analysis and load combinations for nuclear power plants

International Nuclear Information System (INIS)

George, L.L.

1983-01-01

This workshop describes some probability problems in power plant reliability and maintenance analysis. The problems are seismic risk analysis, loss of load probability, load combinations, and load sharing. The seismic risk problem is to compute power plant reliability given an earthquake and the resulting risk. Component survival occurs if its peak random response to the earthquake does not exceed its strength. Power plant survival is a complicated Boolean function of component failures and survivals. The responses and strengths of components are dependent random processes, and the peak responses are maxima of random processes. The resulting risk is the expected cost of power plant failure

Application of computational intelligence techniques for load shedding in power systems: A review

International Nuclear Information System (INIS)

Laghari, J.A.; Mokhlis, H.; Bakar, A.H.A.; Mohamad, Hasmaini

2013-01-01

Highlights: • The power system blackout history of last two decades is presented. • Conventional load shedding techniques, their types and limitations are presented. • Applications of intelligent techniques in load shedding are presented. • Intelligent techniques include ANN, fuzzy logic, ANFIS, genetic algorithm and PSO. • The discussion and comparison between these techniques are provided. - Abstract: Recent blackouts around the world question the reliability of conventional and adaptive load shedding techniques in avoiding such power outages. To address this issue, reliable techniques are required to provide fast and accurate load shedding to prevent collapse in the power system. Computational intelligence techniques, due to their robustness and flexibility in dealing with complex non-linear systems, could be an option in addressing this problem. Computational intelligence includes techniques like artificial neural networks, genetic algorithms, fuzzy logic control, adaptive neuro-fuzzy inference system, and particle swarm optimization. Research in these techniques is being undertaken in order to discover means for more efficient and reliable load shedding. This paper provides an overview of these techniques as applied to load shedding in a power system. This paper also compares the advantages of computational intelligence techniques over conventional load shedding techniques. Finally, this paper discusses the limitation of computational intelligence techniques, which restricts their usage in load shedding in real time

Short-term Power Load Forecasting Based on Balanced KNN

Science.gov (United States)

Lv, Xianlong; Cheng, Xingong; YanShuang; Tang, Yan-mei

2018-03-01

To improve the accuracy of load forecasting, a short-term load forecasting model based on balanced KNN algorithm is proposed; According to the load characteristics, the historical data of massive power load are divided into scenes by the K-means algorithm; In view of unbalanced load scenes, the balanced KNN algorithm is proposed to classify the scene accurately; The local weighted linear regression algorithm is used to fitting and predict the load; Adopting the Apache Hadoop programming framework of cloud computing, the proposed algorithm model is parallelized and improved to enhance its ability of dealing with massive and high-dimension data. The analysis of the household electricity consumption data for a residential district is done by 23-nodes cloud computing cluster, and experimental results show that the load forecasting accuracy and execution time by the proposed model are the better than those of traditional forecasting algorithm.

Magnetic field concentration using ferromagnetic material to propel a wireless power transfer based micro-robot

Directory of Open Access Journals (Sweden)

Dongwook Kim

2018-05-01

Full Text Available In this paper, we propose a novel coil structure, using a ferromagnetic material which concentrates the magnetic field, as the propulsion system of a wireless power transfer (WPT based micro-robot. This structure uses an incident magnetic field to induce current during wireless power transfer, to generate a Lorentz force. To prevent net cancelation of the Lorentz force in the load coil, ferrite films were applied to one side of the coil segment. The demonstrated simplicity and effectiveness of the proposed micro-robot showed its suitability for applications. Simulation and experimental results confirmed a velocity of 1.02 mm/s with 6 mW power transfer capacity for the 3 mm sized micro-robot.

Magnetic field concentration using ferromagnetic material to propel a wireless power transfer based micro-robot

Science.gov (United States)

Kim, Dongwook; Park, Bumjin; Park, Jaehyoung; Park, Hyun Ho; Ahn, Seungyoung

2018-05-01

In this paper, we propose a novel coil structure, using a ferromagnetic material which concentrates the magnetic field, as the propulsion system of a wireless power transfer (WPT) based micro-robot. This structure uses an incident magnetic field to induce current during wireless power transfer, to generate a Lorentz force. To prevent net cancelation of the Lorentz force in the load coil, ferrite films were applied to one side of the coil segment. The demonstrated simplicity and effectiveness of the proposed micro-robot showed its suitability for applications. Simulation and experimental results confirmed a velocity of 1.02 mm/s with 6 mW power transfer capacity for the 3 mm sized micro-robot.

After-hours Power Status of Office Equipment and Inventory of Miscellaneous Plug-load Equipment

Energy Technology Data Exchange (ETDEWEB)

Roberson, Judy A.; Webber, Carrie A.; McWhinney, Marla C.; Brown, Richard E.; Pinckard, Margaret J.; Busch, John F.

2004-01-22

This research was conducted in support of two branches of the EPA ENERGY STAR program, whose overall goal is to reduce, through voluntary market-based means, the amount of carbon dioxide emitted in the U.S. The primary objective was to collect data for the ENERGY STAR Office Equipment program on the after-hours power state of computers, monitors, printers, copiers, scanners, fax machines, and multi-function devices. We also collected data for the ENERGY STAR Commercial Buildings branch on the types and amounts of ''miscellaneous'' plug-load equipment, a significant and growing end use that is not usually accounted for by building energy managers. This data set is the first of its kind that we know of, and is an important first step in characterizing miscellaneous plug loads in commercial buildings. The main purpose of this study is to supplement and update previous data we collected on the extent to which electronic office equipment is turned off or automatically enters a low power state when not in active use. In addition, it provides data on numbers and types of office equipment, and helps identify trends in office equipment usage patterns. These data improve our estimates of typical unit energy consumption and savings for each equipment type, and enables the ENERGY STAR Office Equipment program to focus future effort on products with the highest energy savings potential. This study expands our previous sample of office buildings in California and Washington DC to include education and health care facilities, and buildings in other states. We report data from twelve commercial buildings in California, Georgia, and Pennsylvania: two health care buildings, two large offices (> 500 employees each), three medium offices (50-500 employees), four education buildings, and one ''small office'' that is actually an aggregate of five small businesses. Two buildings are in the San Francisco Bay area of California, five are in

Load management: Model-based control of aggregate power for populations of thermostatically controlled loads

International Nuclear Information System (INIS)

Perfumo, Cristian; Kofman, Ernesto; Braslavsky, Julio H.; Ward, John K.

2012-01-01

Highlights: ► Characterisation of power response of a population of air conditioners. ► Implementation of demand side management on a group of air conditioners. ► Design of a controller for the power output of a group of air conditioners. ► Quantification of comfort impact of demand side management. - Abstract: Large groups of electrical loads can be controlled as a single entity to reduce their aggregate power demand in the electricity network. This approach, known as load management (LM) or demand response, offers an alternative to the traditional paradigm in the electricity market, where matching supply and demand is achieved solely by regulating how much generation is dispatched. Thermostatically controlled loads (TCLs), such as air conditioners (ACs) and fridges, are particularly suitable for LM, which can be implemented using feedback control techniques to regulate their aggregate power. To achieve high performance, such feedback control techniques require an accurate mathematical model of the TCL aggregate dynamics. Although such models have been developed, they appear too complex to be effectively used in control design. In this paper we develop a mathematical model aimed at the design of a model-based feedback control strategy. The proposed model analytically characterises the aggregate power response of a population of ACs to a simultaneous step change in temperature set points. Based on this model, we then derive, and completely parametrise in terms of the ACs ensemble properties, a reduced-order mathematical model to design an internal-model controller that regulates aggregate power by broadcasting temperature set-point offset changes. The proposed controller achieves high LM performance provided the ACs are equipped with high resolution thermostats. With coarser resolution thermostats, which are typical in present commercial and residential ACs, performance deteriorates significantly. This limitation is overcome by subdividing the population

Limitations of power conversion systems under transient loads and impact on the pulsed tokamak power reactor

International Nuclear Information System (INIS)

Sager, G.T.; Wong, C.P.C.; Kapich, D.D.; McDonald, C.F.; Schleicher, R.W.

1993-11-01

The impact of cyclic loading of the power conversion system of a helium-cooled, pulsed tokamak power plant is assessed. Design limits of key components of heat transport systems employing Rankie and Brayton thermodynamic cycles are quantified based on experience in gas-cooled fission reactor design and operation. Cyclic loads due to pulsed tokamak operation are estimated. Expected performance of the steam generator is shown to be incompatible with pulsed tokamak operation without load leveling thermal energy storage. The close cycle gas turbine is evaluated qualitatively based on performance of existing industrial and aeroderivative gas turbines. Advances in key technologies which significantly improve prospects for operation with tokamak fusion plants are reviewed

Limit State of Trapezoidal Metal Sheets Exposed to Concentrated Load

OpenAIRE

Kateřina Jurdová

2013-01-01

In most industrial compounds are used trapezoidal metal sheets like a roof decks. These trapezoidal metal sheets are exposed by concentrated loads, usually by service loads arise from installation of air distribution, sanitary distribution, sprinkler system or wiring installation. In objects of public facilities (like shopping centre, tennis hall, etc.) they can be used for hanging advertising posters etc, too. These systems work as “building kit”. These anchoring systems are represented by c...

Probabilistic decision model of wind power investment and influence of green power market

International Nuclear Information System (INIS)

Gillenwater, Michael

2013-01-01

This paper presents results from a model of a representative wind power investor's decision making process using a Monte Carlo simulation of a project financial analysis. Data, in the form of probability distribution functions (PDFs) for key input variables were collected from interviews with investors and other professionals active in the U.S. wind power industry using a formal expert elicitation protocol. This study presents the first quantitative estimates of the effect of the U.S. voluntary Renewable Energy Certificate (REC) market on renewable energy generation. The results indicate that the investment decisions of wind power project developers in the United States are unlikely to have been altered by the voluntary REC market. The problem with the current voluntary REC market is that it does not offer developers a reliable risk-adjusted revenue stream. Consequently, the claims by U.S. green power retailers and promoters that voluntary market RECs result in additional wind power projects lack credibility. Even dramatic increases in voluntary market REC prices, in the absence of long-term contracts, were found to have only a small effect on investor behavior. - Highlights: • I use a formal expert elicitation to collect data from wind power investors. • I use a Monte Carlo model to look at the influence of Renewable Energy Certificates on investment. • Investment decisions are unlikely to have been altered by the voluntary REC market. • Claims that the U.S. green power market result in additional wind power lack credibility

77 FR 70484 - Preoperational Testing of Onsite Electric Power Systems To Verify Proper Load Group Assignments...

Science.gov (United States)

2012-11-26

...-1294, ``Preoperational Testing of On-Site Electric Power Systems to Verify Proper Load Group... entitled ``Preoperational Testing of On- Site Electric Power Systems to Verify Proper Load Group... Electric Power Systems to Verify Proper Load Group Assignments, Electrical Separation, and Redundancy...

Dynamic analysis of a pumped-storage hydropower plant with random power load

Science.gov (United States)

Zhang, Hao; Chen, Diyi; Xu, Beibei; Patelli, Edoardo; Tolo, Silvia

2018-02-01

This paper analyzes the dynamic response of a pumped-storage hydropower plant in generating mode. Considering the elastic water column effects in the penstock, a linearized reduced order dynamic model of the pumped-storage hydropower plant is used in this paper. As the power load is always random, a set of random generator electric power output is introduced to research the dynamic behaviors of the pumped-storage hydropower plant. Then, the influences of the PI gains on the dynamic characteristics of the pumped-storage hydropower plant with the random power load are analyzed. In addition, the effects of initial power load and PI parameters on the stability of the pumped-storage hydropower plant are studied in depth. All of the above results will provide theoretical guidance for the study and analysis of the pumped-storage hydropower plant.

Mid-term load forecasting of power systems by a new prediction method

International Nuclear Information System (INIS)

Amjady, Nima; Keynia, Farshid

2008-01-01

Mid-term load forecasting (MTLF) becomes an essential tool for today power systems, mainly in those countries whose power systems operate in a deregulated environment. Among different kinds of MTLF, this paper focuses on the prediction of daily peak load for one month ahead. This kind of load forecast has many applications like maintenance scheduling, mid-term hydro thermal coordination, adequacy assessment, management of limited energy units, negotiation of forward contracts, and development of cost efficient fuel purchasing strategies. However, daily peak load is a nonlinear, volatile, and nonstationary signal. Besides, lack of sufficient data usually further complicates this problem. The paper proposes a new methodology to solve it, composed of an efficient data model, preforecast mechanism and combination of neural network and evolutionary algorithm as the hybrid forecast technique. The proposed methodology is examined on the EUropean Network on Intelligent TEchnologies (EUNITE) test data and Iran's power system. We will also compare our strategy with the other MTLF methods revealing its capability to solve this load forecast problem

Voltage Sag Mitigation and Load Reactive Power Compensation by UPQC

OpenAIRE

Ajitha, P; Jananisri, D

2014-01-01

This paper presents Unified Power Quality Conditioner(UPQC) that consist of series inverter and shunt inverter in back to back configuration which simultaneously compensate the power quality(PQ) problems of both voltage sag and load reactive power compensation . In this paper ,Neural network is tool which is considered for solving power quality problems. The simulation results from MATLAB/SIMULINK are discussed to validate the proposed method.

Design of photovoltaic central power station concentrator array

Energy Technology Data Exchange (ETDEWEB)

1984-02-01

A design for a photovoltaic central power station using tracking concentrators has been developed. The 100 MW plant is assumed to be located adjacent to the Saguaro Power Station of Arizona Public Service. The design assumes an advanced Martin Marietta two-axis tracking fresnel lens concentrator. The concentrators are arrayed in 5 MW subfields, each with its own power conditioning unit. The photovoltaic plant output is connected to the existing 115 kV switchyard. The site specific design allows detailed cost estimates for engineering, site preparation, and installation. Collector and power conditioning costs have been treated parametrically.

Effects of resistance training using known vs unknown loads on eccentric-phase adaptations and concentric velocity.

Science.gov (United States)

Hernández-Davó, J L; Sabido, R; Behm, D G; Blazevich, A J

2018-02-01

The aims of this study were to compare both eccentric- and concentric-phase adaptations in highly trained handball players to 4 weeks of twice-weekly rebound bench press throw training with varying loads (30%, 50% and 70% of one-repetition maximum [1-RM]) using either known (KL) or unknown (UL) loads and to examine the relationship between changes in eccentric- and concentric-phase performance. Twenty-eight junior team handball players were divided into two experimental groups (KL or UL) and a control group. KL subjects were told the load prior each repetition, while UL were blinded. For each repetition, the load was dropped and then a rebound bench press at maximum velocity was immediately performed. Both concentric and eccentric velocity as well as eccentric kinetic energy and musculo-articular stiffness prior to the eccentric-concentric transition were measured. Results showed similar increases in both eccentric velocity and kinetic energy under the 30% 1-RM but greater improvements under 50% and 70% 1-RM loads for UL than KL. UL increased stiffness under all loads (with greater magnitude of changes). KL improved concentric velocity only under the 30% 1-RM load while UL also improved under 50% and 70% 1-RM loads. Improvements in concentric movement velocity were moderately explained by changes in eccentric velocity (R 2 =.23-.62). Thus, UL led to greater improvements in concentric velocity, and the improvement is potentially explained by increases in the speed (as well as stiffness and kinetic energy) of the eccentric phase. Unknown load training appears to have significant practical use for the improvement of multijoint stretch-shortening cycle movements. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Scaling relationships between bed load volumes, transport distances, and stream power in steep mountain channels

Science.gov (United States)

Schneider, Johannes M.; Turowski, Jens M.; Rickenmann, Dieter; Hegglin, Ramon; Arrigo, Sabrina; Mao, Luca; Kirchner, James W.

2014-03-01

Bed load transport during storm events is both an agent of geomorphic change and a significant natural hazard in mountain regions. Thus, predicting bed load transport is a central challenge in fluvial geomorphology and natural hazard risk assessment. Bed load transport during storm events depends on the width and depth of bed scour, as well as the transport distances of individual sediment grains. We traced individual gravels in two steep mountain streams, the Erlenbach (Switzerland) and Rio Cordon (Italy), using magnetic and radio frequency identification tags, and measured their bed load transport rates using calibrated geophone bed load sensors in the Erlenbach and a bed load trap in the Rio Cordon. Tracer transport distances and bed load volumes exhibited approximate power law scaling with both the peak stream power and the cumulative stream energy of individual hydrologic events. Bed load volumes scaled much more steeply with peak stream power and cumulative stream energy than tracer transport distances did, and bed load volumes scaled as roughly the third power of transport distances. These observations imply that large bed load transport events become large primarily by scouring the bed deeper and wider, and only secondarily by transporting the mobilized sediment farther. Using the sediment continuity equation, we can estimate the mean effective thickness of the actively transported layer, averaged over the entire channel width and the duration of individual flow events. This active layer thickness also followed approximate power law scaling with peak stream power and cumulative stream energy and ranged up to 0.57 m in the Erlenbach, broadly consistent with independent measurements.

Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet

Directory of Open Access Journals (Sweden)

M. Hamrin

2009-11-01

Full Text Available Here, and in a companion paper by Hamrin et al. (2009 [Scale size and life time of energy conversion regions observed by Cluster in the plasma sheet], we investigate localized energy conversion regions (ECRs in the Earth's plasma sheet. In total we have studied 151 ECRs within 660 h of plasma sheet data from the summer and fall of 2001 when Cluster was close to apogee at an altitude of about 15–20 R_E. Cluster offers appropriate conditions for the investigation of energy conversion by the evaluation of the power density, E·J, where E is the electric field and J the current density. From the sign of the power density, we have identified more than three times as many Concentrated Load Regions (CLRs as Concentrated Generator Regions (CGRs. We also note that the CLRs appear to be stronger. To our knowledge, these are the first in situ observations confirming the general notion of the plasma sheet, on the average, behaving as a load. At the same time the plasma sheet appears to be highly structured, with energy conversion occurring in both directions between the fields and the particles. From our data we also find that the CLRs appear to be located closer to the neutral sheet, while CGRs prefer locations towards the plasma sheet boundary layer (PSBL. For both CLRs and CGRs, E and J in the GSM y (cross-tail direction dominate the total power density, even though the z contribution occasionally can be significant. The prevalence of the y-direction seems to be weaker for the CGRs, possibly related to a higher fluctuation level near the PSBL.

Correlated wind-power production and electric load scenarios for investment decisions

International Nuclear Information System (INIS)

Baringo, L.; Conejo, A.J.

2013-01-01

Highlights: ► Investment models require an accurate representation of the involved uncertainty. ► Demand and wind power production are correlated and uncertain parameters. ► Two methodologies are provided to represent uncertainty and correlation. ► An accurate uncertainty representation is crucial to get optimal results. -- Abstract: Stochastic programming constitutes a useful tool to address investment problems. This technique represents uncertain input data using a set of scenarios, which should accurately describe the involved uncertainty. In this paper, we propose two alternative methodologies to efficiently generate electric load and wind-power production scenarios, which are used as input data for investment problems. The two proposed methodologies are based on the load- and wind-duration curves and on the K-means clustering technique, and allow representing the uncertainty of and the correlation between electric load and wind-power production. A case study pertaining to wind-power investment is used to show the interest of the proposed methodologies and to illustrate how the selection of scenarios has a significant impact on investment decisions.

Transistor-based filter for inhibiting load noise from entering a power supply

Science.gov (United States)

Taubman, Matthew S

2013-07-02

A transistor-based filter for inhibiting load noise from entering a power supply is disclosed. The filter includes a first transistor having an emitter coupled to a power supply, a collector coupled to a load, and a base. The filter also includes a first capacitor coupled between the base of the first transistor and a ground terminal. The filter further includes an impedance coupled between the base and a node between the collector and the load, or a second transistor and second capacitor. The impedance can be a resistor or an inductor.

Microprocessor control unit of thyristor regulator of microhydroelectric power station ballast load

International Nuclear Information System (INIS)

Nomokonova, Yu; Bogdanov, E

2014-01-01

The operational principle of microhydroelectric power station ballast load is presented. The comparative overview of the mathematical modeling methods is performed. The ranges of thyristors optimal work are shown as a result of the regulator regimes analysis. Shows the necessity of regulation the ballast load in microhydroelectric power station with help of developed algorithm of the program for microprocessor control

A fully integrated, wide-load-range, high-power-conversion-efficiency switched capacitor DC-DC converter with adaptive bias comparator for ultra-low-power power management integrated circuit

Science.gov (United States)

Asano, Hiroki; Hirose, Tetsuya; Kojima, Yuta; Kuroki, Nobutaka; Numa, Masahiro

2018-04-01

In this paper, we present a wide-load-range switched-capacitor DC-DC buck converter with an adaptive bias comparator for ultra-low-power power management integrated circuit. The proposed converter is based on a conventional one and modified to operate in a wide load range by developing a load current monitor used in an adaptive bias comparator. Measurement results demonstrated that our proposed converter generates a 1.0 V output voltage from a 3.0 V input voltage at a load of up to 100 µA, which is 20 times higher than that of the conventional one. The power conversion efficiency was higher than 60% in the load range from 0.8 to 100 µA.

Peer Reviews: a voluntary means of enhancing operating culture

International Nuclear Information System (INIS)

Vella, R.

1996-01-01

In the nuclear energy industry, and also in other fields, excellent experience has been gained from the regular accumulation of expert evidence of power station operation through external organizations or teams. In 1991, the World Association of Nuclear Operations (WANO) initiated a pilot programme for voluntary 'Peer Reviews'. The success of this first exercise in gathering expert evidence led to the introduction of the 'Peer Review' programme in 1993 as one of the standard programmes of WANO. The object was to increase the safety and reliability of nuclear power stations throughout the world. WANO Peer Reviews are voluntary and are carried out at the request of a member. They are oriented towards special WANO performance objectives and criteria, which have been established by the management of WANO. (orig.) [de

Concentrating Solar Power Program Review 2013 (Book) (Revised)

Energy Technology Data Exchange (ETDEWEB)

2013-06-01

This U.S. Department of Energy (DOE) Concentrating Solar Power Program Review Meeting booklet will be provided to attendees at the Concentrating Solar Power Review Meeting in Phoenix, Arizona on April 23-25, 2013.

Automatic Power Control for Daily Load-following Operation using Model Predictive Control Method

Energy Technology Data Exchange (ETDEWEB)

Yu, Keuk Jong; Kim, Han Gon [KH, Daejeon (Korea, Republic of)

2009-10-15

Under the circumstances that nuclear power occupies more than 50%, nuclear power plants are required to be operated on load-following operation in order to make the effective management of electric grid system and enhanced responsiveness to rapid changes in power demand. Conventional reactors such as the OPR1000 and APR1400 have a regulating system that controls the average temperature of the reactor core relation to the reference temperature. This conventional method has the advantages of proven technology and ease of implementation. However, this method is unsuitable for controlling the axial power shape, particularly the load following operation. Accordingly, this paper reports on the development of a model predictive control method which is able to control the reactor power and the axial shape index. The purpose of this study is to analyze the behavior of nuclear reactor power and the axial power shape by using a model predictive control method when the power is increased and decreased for a daily load following operation. The study confirms that deviations in the axial shape index (ASI) are within the operating limit.

Nonsafety loads on glass 1E power sources, revisited

International Nuclear Information System (INIS)

Lewin, J.

1980-01-01

The supply of some nonsafety loads from class 1E power sources is allowed by industry standards (IEEE Standards 308 and 384) and by US Nuclear Regulatory Commission Regulatory Guides 1.32 and 1.75. This has been questioned as a possible source of degradation of the class 1E system, and this power deals with assessment of the effects of this practice on the reliability of the power supply for engineered safety features (ESF) systems

Moving from voluntary euthanasia to non-voluntary euthanasia: equality and compassion.

Science.gov (United States)

Amaraskekara, Kumar; Bagaric, Mirko

2004-09-01

The recent Dutch law legalising active voluntary euthanasia will reignite the euthanasia debate. An illuminating method for evaluating the moral status of a practice is to follow the implications of the practice to its logical conclusion. The argument for compassion is one of the central arguments in favour of voluntary active euthanasia. This argument applies perhaps even more forcefully in relation to incompetent patients. If active voluntary euthanasia is legalised, arguments based on compassion and equality will be directed towards legalising active non-voluntary euthanasia in order to make accelerated termination of death available also to the incompetent. The removal of discrimination against the incompetent has the potential to become as potent a catch-cry as the right to die. However, the legalisation of non-voluntary euthanasia is undesirable. A review of the relevant authorities reveals that there is no coherent and workable "best interests" test which can be invoked to decide whether an incompetent patient is better off dead. This provides a strong reason for not stepping onto the slippery path of permitting active voluntary euthanasia.

Transposing Concentration-Discharge Curves onto Unmonitored Catchments to Estimate Seasonal Nutrient Loads

Science.gov (United States)

Minaudo, C.; Moatar, F.; Abbott, B. W.; Dupas, R.; Gascuel-Odoux, C.; Pinay, G.; Roubeix, V.; Danis, P. A.

2017-12-01

Many lakes and reservoirs in Europe suffer from severe eutrophication. Accurate quantification of nutrient loads are critical for effective mitigation measures, but this information is often unknown. For example, in France, only 50 out of 481 lakes and reservoirs have national monitoring allowing estimation of interannual nitrogen and phosphorus loads, and even these loads are computed from low-frequency data. To address this lack of data, we developed a straightforward method to predict seasonal loads in lake tributaries. First, we analyzed concentration-discharge (C-Q) curves in monitored catchments and identified slopes, intercepts, and coefficient of variation of the log(C)-log(Q) regressions determined for both low and high flows, separated by the median daily flow [Moatar et al., 2017]. Then, we used stepwise multiple linear regression models to empirically link the characteristics of C-Q curves with a set of catchment descriptors such as land use, lithology, morphology indices, climate, and hydrological indicators. Modeled C-Q relationships were then used to estimate annual and seasonal nutrient loads in nearby and similar unmonitored catchments. We implemented this approach on a large dataset from France where stream flow was surveyed daily and water quality (suspended solids, nitrate, total phosphorus, and orthophosphate concentrations) was measured on a monthly basis at 233 stations over the past 20 years in catchments from 10 to 3000 km². The concentration at the median daily flow (seen here as a metric of the general level of contamination in a catchment) was predicted with uncertainty ranging between 30 and 100 %, depending on the variable. C-Q slopes were predicted with large errors, but a sensitivity analysis was conducted to determine the impact of C-Q slopes uncertainties on computed annual and seasonal loads. This approach allows estimation of seasonal and annual nutrient loads and could be potentially implemented to improve protection and

Beam-Forming Concentrating Solar Thermal Array Power Systems

Science.gov (United States)

Cwik, Thomas A. (Inventor); Dimotakis, Paul E. (Inventor); Hoppe, Daniel J. (Inventor)

2016-01-01

The present invention relates to concentrating solar-power systems and, more particularly, beam-forming concentrating solar thermal array power systems. A solar thermal array power system is provided, including a plurality of solar concentrators arranged in pods. Each solar concentrator includes a solar collector, one or more beam-forming elements, and one or more beam-steering elements. The solar collector is dimensioned to collect and divert incoming rays of sunlight. The beam-forming elements intercept the diverted rays of sunlight, and are shaped to concentrate the rays of sunlight into a beam. The steering elements are shaped, dimensioned, positioned, and/or oriented to deflect the beam toward a beam output path. The beams from the concentrators are converted to heat at a receiver, and the heat may be temporarily stored or directly used to generate electricity.

Voluntary Control of Residual Antagonistic Muscles in Transtibial Amputees: Feedforward Ballistic Contractions and Implications for Direct Neural Control of Powered Lower Limb Prostheses.

Science.gov (United States)

Huang, Stephanie; Huang, He

2018-04-01

Discrete, rapid (i.e., ballistic like) muscle activation patterns have been observed in ankle muscles (i.e., plantar flexors and dorsiflexors) of able-bodied individuals during voluntary posture control. This observation motivated us to investigate whether transtibial amputees are capable of generating such a ballistic-like activation pattern accurately using their residual ankle muscles in order to assess whether the volitional postural control of a powered ankle prosthesis using proportional myoelectric control via residual muscles could be feasible. In this paper, we asked ten transtibial amputees to generate ballistic-like activation patterns using their residual lateral gastrocnemius and residual tibialis anterior to control a computer cursor via proportional myoelectric control to hit targets positioned at 20% and 40% of maximum voluntary contraction of the corresponding residual muscle. During practice conditions, we asked amputees to hit a single target repeatedly. During testing conditions, we asked amputees to hit a random sequence of targets. We compared movement time to target and end-point accuracy. We also examined motor recruitment synchronization via time-frequency representations of residual muscle activation. The result showed that median end-point error ranged from -0.6% to 1% maximum voluntary contraction across subjects during practice, which was significantly lower compared to testing ( ). Average movement time for all amputees was 242 ms during practice and 272 ms during testing. Motor recruitment synchronization varied across subjects, and amputees with the highest synchronization achieved the fastest movement times. End-point accuracy was independent of movement time. Results suggest that it is feasible for transtibial amputees to generate ballistic control signals using their residual muscles. Future work on volitional control of powered power ankle prostheses might consider anticipatory postural control based on ballistic-like residual

Power system security enhancement through direct non-disruptive load control

Science.gov (United States)

Ramanathan, Badri Narayanan

The transition to a competitive market structure raises significant concerns regarding reliability of the power grid. A need to build tools for security assessment that produce operating limit boundaries for both static and dynamic contingencies is recognized. Besides, an increase in overall uncertainty in operating conditions makes corrective actions at times ineffective leaving the system vulnerable to instability. The tools that are in place for stability enhancement are mostly corrective and suffer from lack of robustness to operating condition changes. They often pose serious coordination challenges. With deregulation, there have also been ownership and responsibility issues associated with stability controls. However, the changing utility business model and the developments in enabling technologies such as two-way communication, metering, and control open up several new possibilities for power system security enhancement. This research proposes preventive modulation of selected loads through direct control for power system security enhancement. Two main contributions of this research are the following: development of an analysis framework and two conceptually different analysis approaches for load modulation to enhance oscillatory stability, and the development and study of algorithms for real-time modulation of thermostatic loads. The underlying analysis framework is based on the Structured Singular Value (SSV or mu) theory. Based on the above framework, two fundamentally different approaches towards analysis of the amount of load modulation for desired stability performance have been developed. Both the approaches have been tested on two different test systems: CIGRE Nordic test system and an equivalent of the Western Electric Coordinating Council test system. This research also develops algorithms for real-time modulation of thermostatic loads that use the results of the analysis. In line with some recent load management programs executed by utilities, two

Artificial intelligence analysis of paraspinal power spectra.

Science.gov (United States)

Oliver, C W; Atsma, W J

1996-10-01

OBJECTIVE: As an aid to discrimination of sufferers with back pain an artificial intelligence neural network was constructed to differentiate paraspinal power spectra. DESIGN: Clinical investigation using surface electromyography. METHOD: The surface electromyogram power spectra from 60 subjects, 33 non-back-pain sufferers and 27 chronic back pain sufferers were used to construct a back propagation neural network that was then tested. Subjects were placed on a test frame in 30 degrees of lumbar forward flexion. An isometric load of two-thirds maximum voluntary contraction was held constant for 30 s whilst surface electromyograms were recorded at the level of the L(4-5). Paraspinal power spectra were calculated and loaded into the input layer of a three-layer back propagation network. The neural network classified the spectra into normal or back pain type. RESULTS: The back propagation neural was shown to have satisfactory convergence with a specificity of 79% and a sensitivity of 80%. CONCLUSIONS: Artificial intelligence neural networks appear to be a useful method of differentiating paraspinal power spectra in back-pain sufferers.

Controlled load with supporting power grid property; Gesteuerte Verbraucher mit netzstuetzender Eigenschaft

Energy Technology Data Exchange (ETDEWEB)

Zimmermann, Olaf; Potthoff, Ulrich [Fraunhofer-Institut fuer Verkehrs- und Infrastruktursysteme (IVI), Dresden (Germany)

2012-07-01

In the German grid, the proportion of volatile energy is steadily increasing for several years. The ratio between energy production and consumption must be always balanced. With the unsteady supply of renewable energy in particular, the power plant and grid control is facing new challenges. At the Fraunhofer Institute for Transportation and Infrastructure Systems was analyzed, if power regulation of selected loads could make a contribution to the reliability of supply. The power consumption should be regulated as a function of the available energy supply. As suitable loads stationary refrigeration equipment or the growing number of plug-in electric vehicles have been identified. The Fraunhofer IVT's approach is an autonomous and decentralized system in which each load accommodates its consumption automatically based on locally determinable network parameters. (orig.)

Constituent concentrations, loads, and yields to Beaver Lake, Arkansas, water years 1999-2008

Science.gov (United States)

Bolyard, Susan E.; De Lanois, Jeanne L.; Green, W. Reed

2010-01-01

Beaver Lake is a large, deep-storage reservoir used as a drinking-water supply and considered a primary watershed of concern in the State of Arkansas. As such, information is needed to assess water quality, especially nutrient enrichment, nutrient-algal relations, turbidity, and sediment issues within the reservoir system. Water-quality samples were collected at three main inflows to Beaver Lake: the White River near Fayetteville, Richland Creek at Goshen, and War Eagle Creek near Hindsville. Water-quality samples collected over the period represented different flow conditions (from low to high). Constituent concentrations, flow-weighted concentrations, loads, and yields from White River, Richland Creek, and War Eagle Creek to Beaver Lake for water years 1999-2008 were documented for this report. Constituents include total ammonia plus organic nitrogen, dissolved nitrite plus nitrate nitrogen, dissolved orthophosphorus (soluble reactive phosphorus), total phosphorus, total nitrogen, dissolved organic carbon, total organic carbon, and suspended sediment. Linear regression models developed by computer program S-LOADEST were used to estimate loads for each constituent for the 10-year period at each station. Constituent yields and flow-weighted concentrations for each of the three stations were calculated for the study. Constituent concentrations and loads and yields varied with time and varied among the three tributaries contributing to Beaver Lake. These differences can result from differences in precipitation, land use, contributions of nutrients from point sources, and variations in basin size. Load and yield estimates varied yearly during the study period, water years 1999-2008, with the least nutrient and sediment load and yields generally occurring in water year 2006, and the greatest occurring in water year 2008, during a year with record amounts of precipitation. Flow-weighted concentrations of most constituents were greatest at War Eagle Creek near Hindsville

Numerical simulation of thermal loading produced by shaped high power laser onto engine parts

International Nuclear Information System (INIS)

Song Hongwei; Li Shaoxia; Zhang Ling; Yu Gang; Zhou Liang; Tan Jiansong

2010-01-01

Recently a new method for simulating the thermal loading on pistons of diesel engines was reported. The spatially shaped high power laser is employed as the heat source, and some preliminary experimental and numerical work was carried out. In this paper, a further effort was made to extend this simulation method to some other important engine parts such as cylinder heads. The incident Gaussian beam was transformed into concentric multi-circular patterns of specific intensity distributions, with the aid of diffractive optical elements (DOEs). By incorporating the appropriate repetitive laser pulses, the designed transient temperature fields and thermal loadings in the engine parts could be simulated. Thermal-structural numerical models for pistons and cylinder heads were built to predict the transient temperature and thermal stress. The models were also employed to find the optimal intensity distributions of the transformed laser beam that could produce the target transient temperature fields. Comparison of experimental and numerical results demonstrated that this systematic approach is effective in simulating the thermal loading on the engine parts.

The impact of hybrid energy storage on power quality, when high power pulsed DC loads are operated on a microgrid testbed

Science.gov (United States)

Kelley, Jay Paul

As the Navy's demands for high power transient loads evolves, so too does the need for alternative energy sources to back-up the more traditional power generation. Such applications in need of support include electrical grid backup and directed energy weapon systems such as electromagnetic launchers, laser systems, and high power microwave generators, among others. Among the alternative generation sources receiving considerable attention are energy storage devices such as rechargeable electrochemical batteries and capacitors. In such applications as those mentioned above, these energy storage devices offer the ability to serve a dual role as both a power source to the various loads as well high power loads themselves to the continual generation when the high power transient loads are in periods of downtime. With the recent developments in electrochemical energy storage, lithium-ion batteries (LIBs) seem like the obvious choice, but previous research has shown that the elevated rates of charging can be detrimental to both the cycle life and the operational life span of the device. In order to preserve the batteries, their charge rate must be limited. One proposed method to accomplish the dual role task mentioned above, while preserving the life of the batteries, is by combining high energy density LIBs with high power density electric double layer capacitors (EDLCs) or lithium-ion capacitors (LICs) using controllable power electronics to adjust the flow of power to and from each device. Such a configuration is typically referred to as hybrid energy storage module (HESM). While shipboard generators start up, the combined high energy density and high power density of the HESM provides the capability to source critical loads for an extended period of time at the high rates they demand. Once the generator is operationally efficient, the HESM can act as a high energy reservoir to harvest the energy from the generator while the loads are in short periods of inactivity

Impact evaluation of conducted UWB transients on loads in power-line networks

Science.gov (United States)

Li, Bing; Månsson, Daniel

2017-09-01

Nowadays, faced with the ever-increasing dependence on diverse electronic devices and systems, the proliferation of potential electromagnetic interference (EMI) becomes a critical threat for reliable operation. A typical issue is the electronics working reliably in power-line networks when exposed to electromagnetic environment. In this paper, we consider a conducted ultra-wideband (UWB) disturbance, as an example of intentional electromagnetic interference (IEMI) source, and perform the impact evaluation at the loads in a network. With the aid of fast Fourier transform (FFT), the UWB transient is characterized in the frequency domain. Based on a modified Baum-Liu-Tesche (BLT) method, the EMI received at the loads, with complex impedance, is computed. Through inverse FFT (IFFT), we obtain time-domain responses of the loads. To evaluate the impact on loads, we employ five common, but important quantifiers, i.e., time-domain peak, total signal energy, peak signal power, peak time rate of change and peak time integral of the pulse. Moreover, to perform a comprehensive analysis, we also investigate the effects of the attributes (capacitive, resistive, or inductive) of other loads connected to the network, the rise time and pulse width of the UWB transient, and the lengths of power lines. It is seen that, for the loads distributed in a network, the impact evaluation of IEMI should be based on the characteristics of the IEMI source, and the network features, such as load impedances, layout, and characteristics of cables.

Observer-Based Load Frequency Control for Island Microgrid with Photovoltaic Power

Directory of Open Access Journals (Sweden)

Chaoxu Mu

2017-01-01

Full Text Available As renewable energy is widely integrated into the power system, the stochastic and intermittent power generation from renewable energy may cause system frequency deviating from the prescribed level, especially for a microgrid. In this paper, the load frequency control (LFC of an island microgrid with photovoltaic (PV power and electric vehicles (EVs is investigated, where the EVs can be treated as distributed energy storages. Considering the disturbances from load change and PV power, an observer-based integral sliding mode (OISM controller is designed to regulate the frequency back to the prescribed value, where the neural network observer is used to online estimate the PV power. Simulation studies on a benchmark microgrid system are presented to illustrate the effectiveness of OISM controller, and comparative results also demonstrate that the proposed method has a superior performance for stabilizing the frequency over the PID control.

Reliability Constrained Priority Load Shedding for Aerospace Power System Automation

Science.gov (United States)

Momoh, James A.; Zhu, Jizhong; Kaddah, Sahar S.; Dolce, James L. (Technical Monitor)

2000-01-01

The need for improving load shedding on board the space station is one of the goals of aerospace power system automation. To accelerate the optimum load-shedding functions, several constraints must be involved. These constraints include congestion margin determined by weighted probability contingency, component/system reliability index, generation rescheduling. The impact of different faults and indices for computing reliability were defined before optimization. The optimum load schedule is done based on priority, value and location of loads. An optimization strategy capable of handling discrete decision making, such as Everett optimization, is proposed. We extended Everett method to handle expected congestion margin and reliability index as constraints. To make it effective for real time load dispatch process, a rule-based scheme is presented in the optimization method. It assists in selecting which feeder load to be shed, the location of the load, the value, priority of the load and cost benefit analysis of the load profile is included in the scheme. The scheme is tested using a benchmark NASA system consisting of generators, loads and network.

Voluntary health insurance in the European Union: a critical assessment.

Science.gov (United States)

Mossialos, Elias; Thomson, Sarah M S

2002-01-01

The authors examine the role and nature of the market for voluntary health insurance in the European Union and review the impact of public policy, at both the national and E.U. levels, on the development of this market in recent years. The conceptual framework, based on a model of industrial analysis, allows a wide range of policy questions regarding market structure, conduct, and performance. By analyzing these three aspects of the market for voluntary health insurance, the authors are also able to raise questions about the equity and efficiency of voluntary health insurance as a means of funding health care in the European Union. The analysis suggests that the market for voluntary health insurance in the European Union suffers from significant information failures that seriously limit its potential for competition or efficiency and also reduce equity. Substantial deregulation of the E.U. market for voluntary health insurance has stripped regulatory bodies of their power to protect consumers and poses interesting challenges for national regulators, particularly if the market is to expand in the future. In a deregulated environment, it is questionable whether this method of funding health care will encourage a more efficient and equitable allocation of resources.

Probabilistic Constrained Load Flow Considering Integration of Wind Power Generation and Electric Vehicles

DEFF Research Database (Denmark)

Vlachogiannis, Ioannis (John)

2009-01-01

A new formulation and solution of probabilistic constrained load flow (PCLF) problem suitable for modern power systems with wind power generation and electric vehicles (EV) demand or supply is represented. The developed stochastic model of EV demand/supply and the wind power generation model...... are incorporated into load flow studies. In the resulted PCLF formulation, discrete and continuous control parameters are engaged. Therefore, a hybrid learning automata system (HLAS) is developed to find the optimal offline control settings over a whole planning period of power system. The process of HLAS...

Theory Study and Application of the BP-ANN Method for Power Grid Short-Term Load Forecasting

Institute of Scientific and Technical Information of China (English)

Xia Hua; Gang Zhang; Jiawei Yang; Zhengyuan Li

2015-01-01

Aiming at the low accuracy problem of power system short⁃term load forecasting by traditional methods, a back⁃propagation artifi⁃cial neural network (BP⁃ANN) based method for short⁃term load forecasting is presented in this paper. The forecast points are re⁃lated to prophase adjacent data as well as the periodical long⁃term historical load data. Then the short⁃term load forecasting model of Shanxi Power Grid (China) based on BP⁃ANN method and correlation analysis is established. The simulation model matches well with practical power system load, indicating the BP⁃ANN method is simple and with higher precision and practicality.

Utilization of Model Predictive Control to Balance Power Absorption Against Load Accumulation

Energy Technology Data Exchange (ETDEWEB)

Abbas, Nikhar [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tom, Nathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-06-03

Wave energy converter (WEC) control strategies have been primarily focused on maximizing power absorption. The use of model predictive control strategies allows for a finite-horizon, multiterm objective function to be solved. This work utilizes a multiterm objective function to maximize power absorption while minimizing the structural loads on the WEC system. Furthermore, a Kalman filter and autoregressive model were used to estimate and forecast the wave exciting force and predict the future dynamics of the WEC. The WEC's power-take-off time-averaged power and structural loads under a perfect forecast assumption in irregular waves were compared against results obtained from the Kalman filter and autoregressive model to evaluate model predictive control performance.

Consequences of mis-loading and the power distribution in bowed fuel assemblies

International Nuclear Information System (INIS)

Andersson, Magnus

2002-04-01

The thesis is divided in two parts. The first part will investigate consequences of a mis-loaded fuel assembly in Ringhals 3, which is a pressurised water reactor (PWR). The aim of this work is to show that there are no or very small benefits from making an additional flux map at 30 % power in order to detect anomalies. Out of the 17 simulations, there exists only one type of mis-loading, which leads to problems. The case, which leads to problems, is when a Gd fitted assembly changes place with a non Gd. This leads to a too high power peaking factor and increased quadrant power tilt. The gain of a flux map at 30% power is small

Consequences of mis-loading and the power distribution in bowed fuel assemblies

Energy Technology Data Exchange (ETDEWEB)

Andersson, Magnus

2002-04-01

The thesis is divided in two parts. The first part will investigate consequences of a mis-loaded fuel assembly in Ringhals 3, which is a pressurised water reactor (PWR). The aim of this work is to show that there are no or very small benefits from making an additional flux map at 30 % power in order to detect anomalies. Out of the 17 simulations, there exists only one type of mis-loading, which leads to problems. The case, which leads to problems, is when a Gd fitted assembly changes place with a non Gd. This leads to a too high power peaking factor and increased quadrant power tilt. The gain of a flux map at 30% power is small.

A stochastic framework for the grid integration of wind power using flexible load approach

International Nuclear Information System (INIS)

Heydarian-Forushani, E.; Moghaddam, M.P.; Sheikh-El-Eslami, M.K.; Shafie-khah, M.; Catalão, J.P.S.

2014-01-01

Highlights: • This paper focuses on the potential of Demand Response Programs (DRPs) to contribute to flexibility. • A stochastic network constrained unit commitment associated with DR is presented. • DR participation levels and electricity tariffs are evaluated on providing a flexible load profile. • Novel quantitative indices for evaluating flexibility are defined to assess the success of DRPs. • DR types and customer participation levels are the main factors to modify the system load profile. - Abstract: Wind power integration has always been a key research area due to the green future power system target. However, the intermittent nature of wind power may impose some technical and economic challenges to Independent System Operators (ISOs) and increase the need for additional flexibility. Motivated by this need, this paper focuses on the potential of Demand Response Programs (DRPs) as an option to contribute to the flexible operation of power systems. On this basis, in order to consider the uncertain nature of wind power and the reality of electricity market, a Stochastic Network Constrained Unit Commitment associated with DR (SNCUCDR) is presented to schedule both generation units and responsive loads in power systems with high penetration of wind power. Afterwards, the effects of both price-based and incentive-based DRPs are evaluated, as well as DR participation levels and electricity tariffs on providing a flexible load profile and facilitating grid integration of wind power. For this reason, novel quantitative indices for evaluating flexibility are defined to assess the success of DRPs in terms of wind integration. Sensitivity studies indicate that DR types and customer participation levels are the main factors to modify the system load profile to support wind power integration

Maximum power point tracker for portable photovoltaic systems with resistive-like load

Energy Technology Data Exchange (ETDEWEB)

De Cesare, G.; Caputo, D.; Nascetti, A. [Department of Electronic Engineering, University of Rome La Sapienza via Eudossiana, 18 00184 Rome (Italy)

2006-08-15

In this work we report on the design and realization of a maximum power point tracking (MPPT) circuit suitable for low power, portable applications with resistive load. The design rules included cost, size and power efficiency considerations. A novel scheme for the implementation of the control loop of the MPPT circuit is proposed, combining good performance with compact design. The operation and performances were simulated at circuit schematic level with simulation program with integrated circuit emphasis (SPICE). The improved operation of a PV system using our MPPT circuit was demonstrated using a purely resistive load. (author)

Advances in High Power Calorimetric Matched Loads for Short Pulses and CW Gyrotrons

International Nuclear Information System (INIS)

Bin, W.M.; Bruschi, A.; Cirant, S.; Gandini, F.; Granucci, G.; Mellera, V.; Muzzini, V.; Nardone, A.; Sozzi, C.; Spinicchia, N.

2006-01-01

The development of high power gyrotrons for plasma physics research needs proper matched and calorimetric loads able to absorb and measure the power, which nowadays is foreseen to be as high as 2 MW during CW operations. To this end IFP/CNR has developed a family of matched loads useful in the mm-wave frequency band for applications ranging from a few ms to CW in pulse length. The different loads in the family, made of an integrating sphere with a partially reflecting coating on the inner wall, are characterized by having the same absorbing geometry for the incoming beam and a different heat removal system for the specific application. Some important advances have been recently achieved from the point of view of the uniformity of power distribution on the absorbing wall and of the load construction. With high precision achieved in the coating thickness a better control of the heating power distribution is possible by proper shaping of the local reflectivity, in addition to the shaping of the mirror dispersing the input beam. A more sophisticated model describing the power distribution has been developed, taking into account a variable thickness of the absorbing coating, the proper shape of the spreading mirror, the frequency of the incoming radiation and the shape of the input beam. Lower coating thickness is shown to be preferable, at equal local reflectivity, from the point of view of a lower peak temperature and thermal stress. The paper describes a load with variable coating thickness along the meridian of the sphere, showing a uniform power deposition on the inner walls. The cooling pipe is completely electroformed on the spherical copper shell, ensuring the maintenance of the correct curvature of the inner surface and a fast heat conduction from the absorbing coating to the water through the thin copper body. For CW use all heated parts of the load must be cooled and this is achieved by 16 electroformed spiral channels. Both short pulse loads (0.1-1 s) and

Systems and methods for providing power to a load based upon a control strategy

Science.gov (United States)

Perisic, Milun; Kajouke, Lateef A; Ransom, Ray M

2013-12-24

Systems and methods are provided for an electrical system. The electrical system includes a load, an interface configured to receive a voltage from a voltage source, and a controller configured to receive the voltage from the voltage source through the interface and to provide a voltage and current to the load. Wherein, when the controller is in a constant voltage mode, the controller provides a constant voltage to the load, when the controller is in a constant current mode, the controller provides a constant current to the load, and when the controller is in a constant power mode, the controller provides a constant power to the load.

Power Load Event Detection and Classification Based on Edge Symbol Analysis and Support Vector Machine

Directory of Open Access Journals (Sweden)

Lei Jiang

2012-01-01

Full Text Available Energy signature analysis of power appliance is the core of nonintrusive load monitoring (NILM where the detailed data of the appliances used in houses are obtained by analyzing changes in the voltage and current. This paper focuses on developing an automatic power load event detection and appliance classification based on machine learning. In power load event detection, the paper presents a new transient detection algorithm. By turn-on and turn-off transient waveforms analysis, it can accurately detect the edge point when a device is switched on or switched off. The proposed load classification technique can identify different power appliances with improved recognition accuracy and computational speed. The load classification method is composed of two processes including frequency feature analysis and support vector machine. The experimental results indicated that the incorporation of the new edge detection and turn-on and turn-off transient signature analysis into NILM revealed more information than traditional NILM methods. The load classification method has achieved more than ninety percent recognition rate.

Impact of optimal load response to real-time electricity price on power system constraints in Denmark

DEFF Research Database (Denmark)

Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte

2010-01-01

Since the hourly spot market price is available one day ahead in Denmark, the price could be transferred to the consumers and they may shift their loads from high price periods to the low price periods in order to save their energy costs. The optimal load response to a real-time electricity price...... and may represent the future of electricity markets in some ways, is chosen as the studied power system in this paper. A distribution system where wind power capacity is 126% of maximum loads is chosen as the study case. This paper presents a nonlinear load optimization method to real-time power price...... for demand side management in order to save the energy costs as much as possible. Simulation results show that the optimal load response to a real-time electricity price has some good impacts on power system constraints in a distribution system with high wind power penetrations....

Impact evaluation of conducted UWB transients on loads in power-line networks

Directory of Open Access Journals (Sweden)

B. Li

2017-09-01

Full Text Available Nowadays, faced with the ever-increasing dependence on diverse electronic devices and systems, the proliferation of potential electromagnetic interference (EMI becomes a critical threat for reliable operation. A typical issue is the electronics working reliably in power-line networks when exposed to electromagnetic environment. In this paper, we consider a conducted ultra-wideband (UWB disturbance, as an example of intentional electromagnetic interference (IEMI source, and perform the impact evaluation at the loads in a network. With the aid of fast Fourier transform (FFT, the UWB transient is characterized in the frequency domain. Based on a modified Baum–Liu–Tesche (BLT method, the EMI received at the loads, with complex impedance, is computed. Through inverse FFT (IFFT, we obtain time-domain responses of the loads. To evaluate the impact on loads, we employ five common, but important quantifiers, i.e., time-domain peak, total signal energy, peak signal power, peak time rate of change and peak time integral of the pulse. Moreover, to perform a comprehensive analysis, we also investigate the effects of the attributes (capacitive, resistive, or inductive of other loads connected to the network, the rise time and pulse width of the UWB transient, and the lengths of power lines. It is seen that, for the loads distributed in a network, the impact evaluation of IEMI should be based on the characteristics of the IEMI source, and the network features, such as load impedances, layout, and characteristics of cables.

Power load limits of the WENDELSTEIN 7-X target elements-comparison of experimental results and design values for power loads up to the critical heat flux

International Nuclear Information System (INIS)

Greuner, H; Boeswirth, B; Boscary, J; Leuprecht, A; Plankensteiner, A

2007-01-01

The power load limits of the WENDELSTEIN7-X divertor target elements were experimentally evaluated with heat loads considerably exceeding the expected operating conditions. The water-cooled elements are designed for steady-state heat flux of 10 MW m -2 and to remove a power load up to 100 kW. The elements must allow a limited operation time at 12 MW m -2 steady-state and should not fail for short pulses of up to 15 MW m -2 for cooling conditions in the subcooled nucleate boiling regime. In the framework of the qualification phase, pre-series target elements were loaded up to 24 MW m -2 without loss of CFC tiles. A critical heat flux at the target of 31 MW m -2 was achieved. The paper discusses the results of the tests performed at the high heat flux test facility GLADIS. The experimental results compared to transient nonlinear fine element method (FEM) calculations confirm a high thermal safety margin of the target design sufficient for plasma operation in W7-X

Support for Voluntary Euthanasia with No Logical Slippery Slope to Non-Voluntary Euthanasia.

Science.gov (United States)

Daskal, Steven

2018-01-01

This paper demonstrates that acceptance of voluntary euthanasia does not generate commitment to either non-voluntary euthanasia or euthanasia on request. This is accomplished through analysis of John Keown's and David Jones's slippery slope arguments, and rejection of their view that voluntary euthanasia requires physicians to judge patients as better off dead. Instead, voluntary euthanasia merely requires physicians to judge patients as within boundaries of appropriate deference. This paper develops two ways of understanding and defending voluntary euthanasia on this model, one focused on the independent value of patients' autonomy and the other on the evidence of well-being provided by patients' requests. Both avoid the purported slippery slopes and both are independently supported by an analogy to uncontroversial elements of medical practice. Moreover, the proposed analyses of voluntary euthanasia suggest parameters for the design of euthanasia legislation, both supporting and challenging elements of existing laws in Oregon and the Netherlands.

Thermal Loading and Lifetime Estimation for Power Device Considering Mission Profiles in Wind Power Converter

DEFF Research Database (Denmark)

Ma, Ke; Liserre, Marco; Blaabjerg, Frede

2015-01-01

for the reliability improvement and also for cost reduction of wind power technology. Unfortunately, the existing lifetime estimation methods for the power electronic converter are not yet suitable in the wind power application, because the comprehensive mission profiles are not well specified and included......As a key component in the wind turbine system, the power electronic converter and its power semiconductors suffer from complicated power loadings related to environment, and are proven to have high failure rates. Therefore, correct lifetime estimation of wind power converter is crucial...... devices, more detailed information of the lifetime-related performance in wind power converter can be obtained. Some experimental results are also included to validate the thermal behavior of power device under different mission profiles....

Wind Farm Active Power Dispatch for Output Power Maximizing Based on a Wind Turbine Control Strategy for Load Minimizing

DEFF Research Database (Denmark)

Zhang, Baohua; Hu, Weihao; Hou, Peng

2015-01-01

Inclusion of the wake effect in the wind farm control design (WF) can increase the total captured power by wind turbines (WTs), which is usually implemented by derating upwind WTs. However, derating the WT without a proper control strategy will increase the structural loads, caused by operation...... in stall mode. Therefore, the WT control strategy for derating operation should be considered in the attempt at maximizing the total captured power while reducing structural loads. Moreover, electrical power loss on the transmission system inside a WF is also not negligible for maximizing the total output...... power of the WF. In this paper, an optimal active power dispatch strategy based on a WT derating strategy and considering the transmission loss is proposed for maximizing the total output power. The active power reference of each WT is chosen as the optimization variable. A partial swarm optimizing...

An Efficient Topology for Wireless Power Transfer over a Wide Range of Loading Conditions

Directory of Open Access Journals (Sweden)

Tianqing Li

2018-01-01

Full Text Available Although an inductive power transfer (IPT system can transfer power efficiently in full-load conditions, its efficiency obviously decreases in light-load conditions. To solve this problem, based on a two-coil IPT system with a series-series compensation topology, a single-ended primary-inductor converter is introduced at the secondary side. By adjusting the set effective value of the current in the primary coil, the converter input voltage changes to maintain the equivalent input resistance of the converter in an optimal condition. The system can then transfer the power efficiently with the wide load conditions. Moreover, the system operates at a constant resonance frequency with a high power factor. Both the simulation and experimentation of a prototype with a 10 W IPT system demonstrate the effectiveness of the proposed topology for wireless power transfer.

Experience with high percent step load decrease from full power in NPP Krsko

International Nuclear Information System (INIS)

Vukovic, V.

2000-01-01

The control system of NPP Kriko, is designed to automatically control the reactor in the power range between 15 and 100 percent of rated power for the following designed transients; - 10 percent step change in load; 5 percent per minute loading and unloading; step full load decrease with the aid of automatically initiated and controlled steam dump. Because station operation below 15 percent of rated power is designed for a period of time during startup or standby conditions, automatic control below 15 percent is not provided. The steam dump accomplishes the following functional tasks: it permits the nuclear plants to accept a sudden 95 percent loss of load without incurring reactor trip; it removes stored energy and residual heat following a reactor trip and brings the plant to equilibrium no-load conditions without actuation of the steam generator safety valves; it permits control of the steam generator pressure at no-load conditions and permits a manually controlled cooldown of the plant. The first two functional tasks are controlled by Tavg. The third is controlled by steam pressure. Interlocks minimise any possibility of an inadvertent actuation of steam dump system. This paper discusses relationships between designed (described) characteristics of plant and the data which are obtained during startup and/or first ten years of operation. (author)

Optimized Power Dispatch in Wind Farms for Power Maximizing Considering Fatigue Loads

DEFF Research Database (Denmark)

Zhang, Baohua; N. Soltani, Mohsen; Hu, Weihao

2018-01-01

Wake effects in a wind farm (WF) include the wind velocity deficit and added turbulence. The wind velocity deficit may bring significant loss of the wind power and the added turbulence may cause extra fatigue load on the wind turbines (WTs). Inclusion of the wake effects in the wind farm control...... at a series of turbulence intensity, mean wind speed and active power reference to form a lookup table, which is used for the WF control. The proposed strategy is compared with WT MPPT control strategy and WF MPPT control strategy. The simulation results show the effectiveness of the proposed strategy....

Power factor improvement in three-phase networks with unbalanced inductive loads using the Roederstein ESTAmat RPR power factor controller

Science.gov (United States)

Diniş, C. M.; Cunţan, C. D.; Rob, R. O. S.; Popa, G. N.

2018-01-01

The paper presents the analysis of a power factor with capacitors banks, without series coils, used for improving power factor for a three-phase and single-phase inductive loads. In the experimental measurements, to improve the power factor, the Roederstein ESTAmat RPR power factor controller can command up to twelve capacitors banks, while experimenting using only six capacitors banks. Six delta capacitors banks with approximately equal reactive powers were used for experimentation. The experimental measurements were carried out with a three-phase power quality analyser which worked in three cases: a case without a controller with all capacitors banks permanently parallel connected with network, and two other cases with power factor controller (one with setting power factor at 0.92 and the other one at 1). When performing experiments with the power factor controller, a current transformer was used to measure the current on one phase (at a more charged or less loaded phase).

Space station electrical power distribution analysis using a load flow approach

Science.gov (United States)

Emanuel, Ervin M.

1987-01-01

The space station's electrical power system will evolve and grow in a manner much similar to the present terrestrial electrical power system utilities. The initial baseline reference configuration will contain more than 50 nodes or busses, inverters, transformers, overcurrent protection devices, distribution lines, solar arrays, and/or solar dynamic power generating sources. The system is designed to manage and distribute 75 KW of power single phase or three phase at 20 KHz, and grow to a level of 300 KW steady state, and must be capable of operating at a peak of 450 KW for 5 to 10 min. In order to plan far into the future and keep pace with load growth, a load flow power system analysis approach must be developed and utilized. This method is a well known energy assessment and management tool that is widely used throughout the Electrical Power Utility Industry. The results of a comprehensive evaluation and assessment of an Electrical Distribution System Analysis Program (EDSA) is discussed. Its potential use as an analysis and design tool for the 20 KHz space station electrical power system is addressed.

Thermal loading of wind power converter considering dynamics of wind speed

DEFF Research Database (Denmark)

Baygildina, Elvira; Peltoniemi, Pasi; Pyrhönen, Olli

2013-01-01

The thermal loading of power semiconductors is a crucial performance related to the reliability and cost of the wind power converter. However, the thermal loading impacts by the variation of wind speeds have not yet been clarified, especially when considering the aerodynamic behavior of the wind...... turbines. In this paper, the junction temperatures in the wind power converter are studied under not only steady state, but also turbulent wind speed conditions. The study is based on a 1.5 MW direct-driven turbine system with aerodynamic model described by Unsteady Blade Element Momentum Method (BEMM......), and the thermal stress of power devices is investigated from the frequency spectrum point of view of wind speed. It is concluded that because of the strong inertia effects by the aerodynamic behavior of wind turbines, thermal stress of the semiconductors is relatively more stable and only influenced by the low...

Nonlinear Robust Control for Low Voltage Direct-Current Residential Microgrids with Constant Power Loads

Directory of Open Access Journals (Sweden)

Martín-Antonio Rodríguez-Licea

2018-05-01

Full Text Available A Direct Current (DC microgrid is a concept derived from a smart grid integrating DC renewable sources. The DC microgrids have three particularities: (1 integration of different power sources and local loads through a DC link; (2 on-site power source generation; and (3 alternating loads (on-off state. This kind of arrangement achieves high efficiency, reliability and versatility characteristics. The key device in the development of the DC microgrid is the power electronic converter (PEC, since it allows an efficient energy conversion between power sources and loads. However, alternating loads with strictly-controlled PECs can provide negative impedance behavior to the microgrid, acting as constant power loads (CPLs, such that the overall closed-loop system becomes unstable. Traditional CPL compensation techniques rely on a damping increment by the adaptation of the source or load voltage level, adding external circuitry or by using some advanced control technique. However, none of them provide a simple and general solution for the CPL problem when abrupt changes in parameters and/or in alternating loads/sources occur. This paper proposes a mathematical modeling and a robust control for the basic PECs dealing with CPLs in continuous conduction mode. In particular, the case of the low voltage residential DC microgrid with CPLs is taken as a benchmark. The proposed controller can be easily tuned for the desired response even by the non-expert. Basic converters with voltage mode control are taken as a basis to show the feasibility of this analysis, and experimental tests on a 100-W testbed include abrupt parameter changes such as input voltage.

Power-aware load balancing of large scale MPI applications

OpenAIRE

Etinski, Maja; Corbalán González, Julita; Labarta Mancho, Jesús José; Valero Cortés, Mateo; Veidenbaum, Alex

2009-01-01

Power consumption is a very important issue for HPC community, both at the level of one application or at the level of whole workload. Load imbalance of a MPI application can be exploited to save CPU energy without penalizing the execution time. An application is load imbalanced when some nodes are assigned more computation than others. The nodes with less computation can be run at lower frequency since otherwise they have to wait for the nodes with more computation blocked in MPI calls. A te...

Loading Concentrations of Pollutant in Alur Ilmu at UKM Bangi Campus: Event Mean Concentration (EMC) Approach

International Nuclear Information System (INIS)

Haslinur Md Din; Mohd Ekhwan Toriman; Mazlin Mokhtar

2012-01-01

Water pollutant loadings and river discharge are among the basic data used in determining the dynamicity of a river. The input of water quality and river discharge are usually available through the collection of water samples in the field or at the observatory, and are done automatically using the data logger sensor. This paper discusses the concentrations pollutant load water quality and its relationship with discharge (m 3 / s) using Event Mean Concentration (EMC) in the Alur Ilmu, UKM source from the Diptrokarp forest at Hutan Simpan Bangi (2 degree 55' 1 4.72 N 101 degree 46' 5 7.37 E). Alur Ilmu is a 1.79 km long stretching across the main campus of National University of Malaysia before flowing into the Langat River. Water quality was measured using automatic gauging and continuous water quality stations which are installed at downstream of Alur Ilmu (2 degree 55 ' 40.33 N 100 degree 46 ' 47.15 E) and involves in measuring the parameters of total dissolved solid (TDS) and dissolved oxygen (DO). Laboratory analysis carried out for chemical parameters such as ammonia nitrogen (NH 3 -N), total suspended solid (TSS), biochemical oxygen demand (BOD) and chemical oxygen demand (COD) in accordance with guidelines American Public Health Association (APHA, 1995). The normal discharge rate recorded at Alur Ilmu is 0.33 m 3 / s and the wet discharge is 13.04 m 3 / s.The total estimated pollutant loadings according to EMC as DO (18.51±3.01 mg/ L), TDS (794.92±186.72 mg/ L), BOD (11.57±0.28 mg/ L), COD (201.29±1.55 mg/ l), TSS (470.03±27.63 mg/ L) and Ammonia Nitrogen (2.52±0.0 mg/ L). Correlation test showed a direct relationship between rainfall and flow (Q) and several pollutant loadings with R 2 =1 at a significance level of 0.05. The study also classified some of the pollutants concentrations in class III and IV as determined by the Water Quality Index (WQI). (author)

The empirical slippery slope from voluntary to non-voluntary euthanasia.

Science.gov (United States)

Lewis, Penney

2007-01-01

This article examines the evidence for the empirical argument that there is a slippery slope between the legalization of voluntary and non-voluntary euthanasia. The main source of evidence in relation to this argument comes from the Netherlands. The argument is only effective against legalization if it is legalization which causes the slippery slope. Moreover, it is only effective if it is used comparatively-to show that the slope is more slippery in jurisdictions which have legalized voluntary euthanasia than it is in jurisdictions which have not done so. Both of these elements are examined comparatively.

Superposition of automatic and voluntary aspects of grip force control in humans during object manipulation.

Directory of Open Access Journals (Sweden)

Frederic Danion

Full Text Available When moving grasped objects, people automatically modulate grip force (GF with movement-dependent load force (LF in order to prevent object slip. However, GF can also be modulated voluntarily as when squeezing an object. Here we investigated possible interactions between automatic and voluntary GF control. Participants were asked to generate horizontal cyclic movements (between 0.6 and 2.0 Hz of a hand-held object that was restrained by an elastic band such that the load force (LF reached a peak once per movement cycle, and to simultaneously squeeze the object at each movement reversal (i.e., twice per cycle. Participants also performed two control tasks in which they either only moved (between 0.6 and 2.0 Hz or squeezed (between 1.2 and 4.0 Hz the object. The extent to which GF modulation in the simultaneous task could be predicted from the two control tasks was assessed using power spectral analyses. At all frequencies, the GF power spectra from the simultaneous task exhibited two prominent components that occurred at the cycle frequency (ƒ and at twice this frequency (2ƒ, whereas the spectra from the movement and squeeze control task exhibited only single peaks at ƒ and 2ƒ, respectively. At lower frequencies, the magnitudes of both frequency components in the simultaneous task were similar to the magnitudes of the corresponding components in the control tasks. However, as frequency increased, the magnitudes of both components in the simultaneous task were greater than the magnitudes of the corresponding control task components. Moreover, the phase relationship between the ƒ components of GF and LF began to drift from the value observed in the movement control task. Overall these results suggest that, at lower movement frequencies, voluntary and automatic GF control processes operate at different hierarchical levels. Several mechanisms are discussed to account for interaction effects observed at higher movement frequencies.

PROBABILISTIC FLOW DISTRIBUTION AS A REACTION TO THE STOCHASTICITY OF THE LOAD IN THE POWER SYSTEM

Directory of Open Access Journals (Sweden)

A. M. Hashimov

2016-01-01

Full Text Available For the analysis and control of power systems deterministic approaches that are implemented in the form of well-known methods and models of calculation of steady-state and transient modes are mostly use in current practice. With the use of these methods it is possible to obtain solutions only for fixed circuit parameters of the system scheme and assuming that active and reactive powers as well as generation in nodal points of the network remain the same. In reality the stochastic character of power consumption cause the casual fluctuations of voltages at the nodes and power flows in electric power lines of the power system. Such casual fluctuations of operation can be estimated with the use of probabilistic simulation of the power flows. In the article the results of research of the influence of depth of casual fluctuations of the load power of the system on the probability distribution of voltage at nodes as well as on the flows of active and reactive power in the lines are presented. Probabilistic modeling of flow under stochastic load change is performed for different levels of fluctuations and under loading of the mode of the system up to peak load power. Test study to quantify the effect of stochastic variability of loads on the probabilistic distribution parameters of the modes was carried out on behalf of the electrical network of the real power system. The results of the simulation of the probability flow distribution for these fluctuations of the load, represented in the form of discrete sample values of the active power obtained with the use of the analytical Monte-Carlo method, and real data measurements of their values in the network under examination were compared.

Optimization Strategy for Economic Power Dispatch Utilizing Retired EV Batteries as Flexible Loads

Directory of Open Access Journals (Sweden)

Shubo Hu

2018-06-01

Full Text Available With the increasing penetration of new and renewable energy, incorporating variable adjustable power elements on the demand side is of particular interest. The utilization of batteries as flexible loads is a hot research topic. Lithium-ion batteries are key components in electric vehicles (EVs in terms of capital cost, mass and size. They are retired after around 5 years of service, but still retain up to 80% of their nominal capacity. Disposal of waste batteries will become a significant issue for the automotive industry in the years to come. This work proposes the use of the second life of these batteries as flexible loads to participate in the economic power dispatch. The characteristics of second life batteries (SLBs are varied and diverse, requiring a new optimization strategy for power dispatch at the system level. In this work, SLBs are characterized and their operating curves are obtained analytically for developing an economic power dispatch model involving wind farms and second life batteries. In addition, a dispatch strategy is developed to reduce the dispatch complex brought by the disperse spatial and time distribution of EVs and decrease the system operating cost by introducing incentive and penalty costs in regulating the EV performance. In theory, SLBs are utilized to reduce the peak-valley difference of power loads and to stabilize the power system. Test results based on a ten-unit power system have verified the effectiveness of the proposed dispatch model and the economic benefit of utilizing SLBs as flexible loads in power systems. This work may provide a viable solution to the disposal of waste batteries from EVs and to the stable operation of fluctuating power systems incorporating stochastic renewable energy.

A 2-megawatt load for testing high voltage DC power supplies

International Nuclear Information System (INIS)

Horan, D.; Kustom, R.; Ferguson, M.; Primdahl, K.

1993-01-01

A high power water-cooled resistive load, capable of dissipating 2 Megawatts at 95 kilovolts is being designed and built. The load utilizes wirewound resistor elements suspended inside insulating tubing contained within a pressure vessel which is supplied a continuous flow of deionized water for coolant. A sub-system of the load is composed of non-inductive resistor elements in an oil tank. Power tests conducted on various resistor types indicate that dissipation levels as high as 22 times the rated dissipation in air can be achieved when the resistors are placed in a turbulent water flow of at least 15 gallons per minute. Using this data, the load was designed using 100 resistor elements in a series arrangement. A single-wall 316 stainless steel pressure vessel with flanged torispherical heads is built to contain the resistor assembly and deionized water. The resistors are suspended within G-11 tubing which span the cylindrical length of the vessel. These tubes are supported by G-10 baffles which also increase convection from the tubes by promoting turbulence within the surrounding water

New series active power filter for computers loads and small non-linear loads

Energy Technology Data Exchange (ETDEWEB)

Tarnini, M.Y. [Hariri Canadian Univ., Meshref (Lebanon)

2009-07-01

This paper proposed the use of a single-phase series active power filter to reduce voltage total harmonic distortion and provide improved power quality. Control schemes were developed using simple control algorithms and a reduced number of current transducers. The circuit was comprised of a power supply and zero crossing detector; a hall-effect current sensor and signal conditioning circuit; a microcontroller circuit; a driving circuit; and an inverter bridge. The filter corrected fundamental and sinusoidal voltage amplitudes. The amplitude of the fundamental current in the series filter was controlled using a microcontroller placed between the load voltage and a pre-established reference point. Experiments were conducted to test the source voltage and source current after compensation using a prototype of the filter. The control system provided effective correction of the power factor and harmonic distortion, and reached steady state in approximately 2 cycles. It was concluded that the compensator can also be adapted for use in 3-phase systems. 13 refs., 1 tab., 14 figs.

Life cycle assessment and evaluation of energy payback time on high-concentration photovoltaic power generation system

International Nuclear Information System (INIS)

Nishimura, A.; Hayashi, Y.; Tanaka, K.; Hirota, M.; Kato, S.; Ito, M.; Araki, K.; Hu, E.J.

2010-01-01

In this study, the environmental load of photovoltaic power generation system (PV) during its life cycle and energy payback time (EPT) are evaluated by LCA scheme. Two hypothetical case studies in Toyohashi, Japan and Gobi dessert in China have been carried out to investigate the influence of installation location and PV type on environmental load and EPT. The environmental load and EPT of a high-concentration photovoltaic power generation system (hcpV) and a multi-crystalline silicon photovoltaic power generation system (mc-Si PV) are studied. The study shows for a PV of 100 MW size, the total impacts of the hcpV installed in Toyohashi is larger than that of the hcpV installed in Gobi desert by 5% without consideration of recycling stage. The EPT of the hcpV assumed to be installed in Gobi desert is shorter than EPT of the hcpV assumed to be installed in Toyohashi by 0.64 year. From these results, the superiority to install PV in Gobi desert is certificated. Comparing with hcpV and mc-Si PV, the ratio of the total impacts of mc-Si PV to that of hcpV is 0.34 without consideration of recycling stage. The EPT of hcpV is longer than EPT of mc-Si PV by 0.27 year. The amount of global solar radiation contributing to the amount of power generation of mc-Si PV is larger than the amount of direct solar radiation contributing to the amount of power generation of hcpV by about 188 kW h/(m 2 year) in Gobi desert. Consequently, it appears that using mc-Si PV in Gobi desert is the best option.

Balancing the Power-to-Load Ratio for a Novel Variable Geometry Wave Energy Converter with Nonideal Power Take-Off in Regular Waves: Preprint

Energy Technology Data Exchange (ETDEWEB)

Tom, Nathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yu, Yi-Hsiang [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wright, Alan D [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-09-28

This work attempts to balance power absorption against structural loading for a novel variable geometry wave energy converter. The variable geometry consists of four identical flaps that will be opened in ascending order starting with the flap closest to the seafloor and moving to the free surface. The influence of a pitch motion constraint on power absorption when utilizing a nonideal power take-off (PTO) is examined and found to reduce the losses associated with bidirectional energy flow. The power-to-load ratio is evaluated using pseudo-spectral control to determine the optimum PTO torque based on a multiterm objective function. The pseudo-spectral optimal control problem is extended to include load metrics in the objective function, which may now consist of competing terms. Separate penalty weights are attached to the surge-foundation force and PTO control torque to tune the optimizer performance to emphasize either power absorption or load shedding. PTO efficiency is not included in the objective function, but the penalty weights are utilized to limit the force and torque amplitudes, thereby reducing losses associated with bidirectional energy flow. Results from pseudo-spectral control demonstrate that shedding a portion of the available wave energy can provide greater reductions in structural loads and reactive power.

Load characteristics of wireless power transfer system with different resonant types and resonator numbers

Science.gov (United States)

Zhang, Yiming; Zhao, Zhengming; Chen, Kainan; Fan, Jun

2017-05-01

Wireless Power Transfer (WPT) has been the research focus and applied in many fields. Normally power is transferred wirelessly to charge the battery, which requires specific load characteristics. The load characteristics are essential for the design and operation of the WPT system. This paper investigates the load characteristics of the WPT system with different resonant types and resonator numbers. It is found that in a WPT system with series or LCL resonance under a constant voltage source, the load characteristic is determined by the number of inductors. Even number of inductors results in a constant current characteristic and odd number constant voltage characteristic. Calculations, simulations, and experiments verify the analysis.

Sex differences in neuromuscular function after repeated eccentric contractions of the knee extensor muscles.

Science.gov (United States)

Lee, Andrea; Baxter, Jake; Eischer, Claire; Gage, Matt; Hunter, Sandra; Yoon, Tejin

2017-06-01

This study examined the mechanisms for force and power reduction during and up to 48 h after maximal eccentric contractions of the knee extensor muscles in young men and women. 13 men (22.8 ± 2.6 years) and 13 women (21.6 ± 2.2 years) performed 150 maximal effort eccentric contractions (5 sets of 30) with the knee extensor muscles at 60° s -1 . Maximal voluntary isometric contractions (MVIC) and maximal voluntary concentric contractions (MVCC) were performed before and after the 150 eccentric contractions. The MVCCs involved a set of two isokinetic contractions at 60° s -1 and sets of isotonic contractions performed at seven different resistance loads (1 N m, 10, 20, 30, 40, 50, and 60% MVIC). Electrical stimulation was used during the MVICs and at rest to determine changes in voluntary activation and contractile properties. At baseline, men were stronger than women (MVIC: 276 ± 48 vs. 133 ± 37 N m) and more powerful (MVCC: 649 ± 77 vs. 346 ± 78 W). At termination of the eccentric contractions, voluntary activation, resting twitch amplitude, and peak power during concentric contractions at the seven loads and at 60° s -1 decreased (P  0.05) with no sex differences. Central mechanisms were primarily responsible for the depressed maximal force production up to 48 h after repeated eccentric contractions of the knee extensors and these mechanisms were similar in men and women.

Power system operation risk analysis considering charging load self-management of plug-in hybrid electric vehicles

International Nuclear Information System (INIS)

Liu, Zhe; Wang, Dan; Jia, Hongjie; Djilali, Ned

2014-01-01

Highlights: • The interactive mechanism between system and PHEVs is presented. • The charging load self-management without sacrificing user requirements is proposed. • The charging load self-management is coupled to system operation risk analysis. • The charging load self-management can reduce the extra risk brought by PHEVs. • The charging load self-management can shift charging power to the time with low risk. - Abstract: Many jurisdictions around the world are supporting the adoption of electric vehicles through incentives and the deployment of a charging infrastructure to reduce greenhouse gas emissions. Plug-in hybrid electric vehicles (PHEVs), with offer mature technology and stable performance, are expected to gain an increasingly larger share of the consumer market. The aggregated effect on power grid due to large-scale penetration of PHEVs needs to be analyzed. Nighttime-charging which typically characterizes PHEVs is helpful in filling the nocturnal load valley, but random charging of large PHEV fleets at night may result in new load peaks and valleys. Active response strategy is a potentially effective solution to mitigate the additional risks brought by the integration of PHEVs. This paper proposes a power system operation risk analysis framework in which charging load self-management is used to control system operation risk. We describe an interactive mechanism between the system and PHEVs in conjunction with a smart charging model is to simulate the time series power consumption of PHEVs. The charging load is managed with adjusting the state transition boundaries and without violating the users’ desired charging constraints. The load curtailment caused by voltage or power flow violation after outages is determined by controlling charging power. At the same time, the system risk is maintained under an acceptable level through charging load self-management. The proposed method is implemented using the Roy Billinton Test System (RBTS) and

Concentration: The Neural Underpinnings of How Cognitive Load Shields Against Distraction.

Science.gov (United States)

Sörqvist, Patrik; Dahlström, Örjan; Karlsson, Thomas; Rönnberg, Jerker

2016-01-01

Whether cognitive load-and other aspects of task difficulty-increases or decreases distractibility is subject of much debate in contemporary psychology. One camp argues that cognitive load usurps executive resources, which otherwise could be used for attentional control, and therefore cognitive load increases distraction. The other camp argues that cognitive load demands high levels of concentration (focal-task engagement), which suppresses peripheral processing and therefore decreases distraction. In this article, we employed an functional magnetic resonance imaging (fMRI) protocol to explore whether higher cognitive load in a visually-presented task suppresses task-irrelevant auditory processing in cortical and subcortical areas. The results show that selectively attending to an auditory stimulus facilitates its neural processing in the auditory cortex, and switching the locus-of-attention to the visual modality decreases the neural response in the auditory cortex. When the cognitive load of the task presented in the visual modality increases, the neural response to the auditory stimulus is further suppressed, along with increased activity in networks related to effortful attention. Taken together, the results suggest that higher cognitive load decreases peripheral processing of task-irrelevant information-which decreases distractibility-as a side effect of the increased activity in a focused-attention network.

Optimization of Boiler Control to Improve the Load-following Capability of Power-plant Units

OpenAIRE

Mortensen, J. H.; Mølbak, T.; Andersen, Palle; Pedersen, Tom Søndergaard

1998-01-01

The capability to perform fast load changes has been an important issue in the power market, and will become increasingly more so due to the incresing commercialisation of the European power market. An optimizing control system for improving the load-following capability of power-plant units has therefore been developed. The system is implemented as a complement, producing control signals to be added to those of the existing boiler control system, a concept which has various practical advanta...

Energy management for vehicle power net with flexible electric load demand

NARCIS (Netherlands)

Kessels, J.T.B.A.; Bosch, van den P.P.J.; Koot, M.W.T.; Jager, de A.G.

2005-01-01

The electric power demand in road vehicles increases rapidly and to supply all electric loads efficiently, energy management (EM) turns out to be a necessity. In general, EM exploits the storage capacity of a buffer connected to the vehicle's power net, such that energy is stored or retrieved at

Multi-timescale modelling for the loading behaviours of power electronics converter

DEFF Research Database (Denmark)

Ma, Ke; Blaabjerg, Frede

2015-01-01

The thermal dynamics of power device, referred as “thermal cycling”, are closely related to the reliability as well as the cost of the power electronics converter. However, the device loading is disturbed by many factors of the converter system which present at various times-constants from micro...

Power Stabilization Strategy of Random Access Loads in Electric Vehicles Wireless Charging System at Traffic Lights

Directory of Open Access Journals (Sweden)

Linlin Tan

2016-10-01

Full Text Available An opportunity wireless charging system for electric vehicles when they stop and wait at traffic lights is proposed in this paper. In order to solve the serious power fluctuation caused by random access loads, this study presents a power stabilization strategy based on counting the number of electric vehicles in a designated area, including counting method, power source voltage adjustment strategy and choice of counting points. Firstly, the circuit model of a wireless power system with multi-loads is built and the equation of each load is obtained. Secondly, after the counting method of electric vehicles is stated, the voltage adjustment strategy, based on the number of electric vehicles when the system is at a steady state, is set out. Then, the counting points are chosen according to power curves when the voltage adjustment strategy is adopted. Finally, an experimental prototype is implemented to verify the power stabilization strategy. The experimental results show that, with the application of this strategy, the charging power is stabilized with the fluctuation of no more than 5% when loads access randomly.

Power analysis and simulation of a vehicle under combined loads

International Nuclear Information System (INIS)

Khayyam, H.; Kouzani, A.Z.; Khoshmanesh, K.; Hu, E.

2008-01-01

Reducing fuel consumption in vehicles offers many obvious economic benefits, and also helps reduce air pollution emission levels. Mechanical engineers and automotive researches have continuously searched for ways to optimize fuel consumption in vehicles. This paper presented an analytical model of fuel consumption (AMFC) in an effort to coordinate the driving power and manage the overall fuel consumption for an internal combustion engine vehicle. The model calculated the different loads applied on the vehicle, such as road-slope, road-friction, wind-drag, accessories, and mechanical losses. It also solved the combustion equation of the engine under different working conditions including various fuel compositions, excess airs and air inlet temperatures. The model then determined the contribution of each load to signify the energy distribution and power flows of the vehicle. In order to assess the model's sensitivity to different loads, the following four simulations were conducted: flat-windless, flat-windy, sloppy-windless, sloppy-windy. The average fuel consumption for the four simulations was presented. The paper outlined the specification of the vehicle and environment as well as the simulation methodology. The model, algorithm, slope simulation, and drive strategy were presented. It was concluded that the power consumption significantly increased where the slope friction came into play and that the model has the potential to assist in vehicle energy management. 16 refs., 4 tabs., 14 figs

Analysis of Interrelationships among Voluntary and Prosthetic Leg Joint Parameters Using Cyclograms.

Science.gov (United States)

Jasni, Farahiyah; Hamzaid, Nur Azah; Mohd Syah, Nor Elleeiana; Chung, Tze Y; Abu Osman, Noor Azuan

2017-01-01

The walking mechanism of a prosthetic leg user is a tightly coordinated movement of several joints and limb segments. The interaction among the voluntary and mechanical joints and segments requires particular biomechanical insight. This study aims to analyze the inter-relationship between amputees' voluntary and mechanical coupled leg joints variables using cyclograms. From this analysis, the critical gait parameters in each gait phase were determined and analyzed if they contribute to a better powered prosthetic knee control design. To develop the cyclogram model, 20 healthy able-bodied subjects and 25 prosthesis and orthosis users (10 transtibial amputees, 5 transfemoral amputees, and 10 different pathological profiles of orthosis users) walked at their comfortable speed in a 3D motion analysis lab setting. The gait parameters (i.e., angle, moment and power for the ankle, knee and hip joints) were coupled to form 36 cyclograms relationship. The model was validated by quantifying the gait disparities of all the pathological walking by analyzing each cyclograms pairs using feed-forward neural network with backpropagation. Subsequently, the cyclogram pairs that contributed to the highest gait disparity of each gait phase were manipulated by replacing it with normal values and re-analyzed. The manipulated cyclograms relationship that showed highest improvement in terms of gait disparity calculation suggested that they are the most dominant parameters in powered-knee control. In case of transfemoral amputee walking, it was identified using this approach that at each gait sub-phase, the knee variables most responsible for closest to normal walking were: knee power during loading response and mid-stance, knee moment and knee angle during terminal stance phase, knee angle and knee power during pre-swing, knee angle at initial swing, and knee power at terminal swing. No variable was dominant during mid-swing phase implying natural pendulum effect of the lower limb between

Analysis of Interrelationships among Voluntary and Prosthetic Leg Joint Parameters Using Cyclograms

Directory of Open Access Journals (Sweden)

Nur Azah Hamzaid

2017-04-01

Full Text Available The walking mechanism of a prosthetic leg user is a tightly coordinated movement of several joints and limb segments. The interaction among the voluntary and mechanical joints and segments requires particular biomechanical insight. This study aims to analyze the inter-relationship between amputees' voluntary and mechanical coupled leg joints variables using cyclograms. From this analysis, the critical gait parameters in each gait phase were determined and analyzed if they contribute to a better powered prosthetic knee control design. To develop the cyclogram model, 20 healthy able-bodied subjects and 25 prosthesis and orthosis users (10 transtibial amputees, 5 transfemoral amputees, and 10 different pathological profiles of orthosis users walked at their comfortable speed in a 3D motion analysis lab setting. The gait parameters (i.e., angle, moment and power for the ankle, knee and hip joints were coupled to form 36 cyclograms relationship. The model was validated by quantifying the gait disparities of all the pathological walking by analyzing each cyclograms pairs using feed-forward neural network with backpropagation. Subsequently, the cyclogram pairs that contributed to the highest gait disparity of each gait phase were manipulated by replacing it with normal values and re-analyzed. The manipulated cyclograms relationship that showed highest improvement in terms of gait disparity calculation suggested that they are the most dominant parameters in powered-knee control. In case of transfemoral amputee walking, it was identified using this approach that at each gait sub-phase, the knee variables most responsible for closest to normal walking were: knee power during loading response and mid-stance, knee moment and knee angle during terminal stance phase, knee angle and knee power during pre-swing, knee angle at initial swing, and knee power at terminal swing. No variable was dominant during mid-swing phase implying natural pendulum effect of the

Load control services in the management of power system security costs

International Nuclear Information System (INIS)

Jayantilal, A.; Strbac, G.

1999-01-01

The new climate of deregulation in the electricity industry is creating a need for a more transparent cost structure and within this framework the cost of system security has been a subject of considerable interest. Traditionally power system security has been supplied by out-of-merit generation, in the short term, and transmission reinforcement, in the long term. This paper presents a method of analysing the role of load-demand in the management of power system security costs by utilising load control services (LCS). It also proposes a competitive market to enable bidding from various participants within the electricity industry to supply system security. (author)

Electrical engineering unit for the reactive power control of the load bus at the voltage instability

Science.gov (United States)

Kotenev, A. V.; Kotenev, V. I.; Kochetkov, V. V.; Elkin, D. A.

2018-01-01

For the purpose of reactive power control error reduction and decrease of the voltage sags in the electric power system caused by the asynchronous motors started the mathematical model of the load bus was developed. The model was built up of the sub-models of the following elements: a transformer, a transmission line, a synchronous and an asynchronous loads and a capacitor bank load, and represents the automatic reactive power control system taking into account electromagnetic processes of the asynchronous motors started and reactive power changing of the electric power system elements caused by the voltage fluctuation. The active power/time and reactive power/time characteristics based on the recommended procedure of the equivalent electric circuit parameters calculation were obtained. The derived automatic reactive power control system was shown to eliminate the voltage sags in the electric power system caused by the asynchronous motors started.

Utilization of Model Predictive Control to Balance Power Absorption Against Load Accumulation: Preprint

Energy Technology Data Exchange (ETDEWEB)

Abbas, Nikhar; Tom, Nathan

2017-09-01

Wave energy converter (WEC) control strategies have been primarily focused on maximizing power absorption. The use of model predictive control strategies allows for a finite-horizon, multiterm objective function to be solved. This work utilizes a multiterm objective function to maximize power absorption while minimizing the structural loads on the WEC system. Furthermore, a Kalman filter and autoregressive model were used to estimate and forecast the wave exciting force and predict the future dynamics of the WEC. The WEC's power-take-off time-averaged power and structural loads under a perfect forecast assumption in irregular waves were compared against results obtained from the Kalman filter and autoregressive model to evaluate model predictive control performance.

Utility-Scale Concentrating Solar Power and Photovoltaic Projects: A Technology and Market Overview

Energy Technology Data Exchange (ETDEWEB)

Mendelsohn, M.; Lowder, T.; Canavan, B.

2012-04-01

Over the last several years, solar energy technologies have been, or are in the process of being, deployed at unprecedented levels. A critical recent development, resulting from the massive scale of projects in progress or recently completed, is having the power sold directly to electric utilities. Such 'utility-scale' systems offer the opportunity to deploy solar technologies far faster than the traditional 'behind-the-meter' projects designed to offset retail load. Moreover, these systems have employed significant economies of scale during construction and operation, attracting financial capital, which in turn can reduce the delivered cost of power. This report is a summary of the current U.S. utility-scale solar state-of-the-market and development pipeline. Utility-scale solar energy systems are generally categorized as one of two basic designs: concentrating solar power (CSP) and photovoltaic (PV). CSP systems can be further delineated into four commercially available technologies: parabolic trough, central receiver (CR), parabolic dish, and linear Fresnel reflector. CSP systems can also be categorized as hybrid, which combine a solar-based system (generally parabolic trough, CR, or linear Fresnel) and a fossil fuel energy system to produce electric power or steam.

Capillary Ion Concentration Polarization for Power-Free Salt Purification

Science.gov (United States)

Park, Sungmin; Jung, Yeonsu; Cho, Inhee; Kim, Ho-Young; Kim, Sung Jae

2014-11-01

In this presentation, we experimentally and theoretically demonstrated the capillary based ion concentration polarization for power-free salt purification system. Traditional ion concentration polarization phenomenon has been studied for a decade for both fundamental nanoscale fluid dynamics and novel engineering applications such as desalination, preconcentration and energy harvesting devices. While the conventional system utilizes an external power source, the system based on capillary ion concentration polarization is capable of perm-selective ion transportation only by capillarity so that the same ion depletion zone can be formed without any external power sources. An ion concentration profile near the nanostructure was tracked using fluorescent probes and analyzed by solving the modified Nernst-Planck equation. As a result, the concentration in the vicinity of the nanostructure was at least 10 times lower than that of bulk electrolyte and thus, the liquid absorbed into the nanostructure had the low concentration. This mechanism can be used for the power free salt purification system which would be significantly useful in underdeveloped and remote area. This work was supported by Samsung Research Funding Center of Samsung Electronics under Project Number SRFC-MA1301-02.

Short-term load and wind power forecasting using neural network-based prediction intervals.

Science.gov (United States)

Quan, Hao; Srinivasan, Dipti; Khosravi, Abbas

2014-02-01

Electrical power systems are evolving from today's centralized bulk systems to more decentralized systems. Penetrations of renewable energies, such as wind and solar power, significantly increase the level of uncertainty in power systems. Accurate load forecasting becomes more complex, yet more important for management of power systems. Traditional methods for generating point forecasts of load demands cannot properly handle uncertainties in system operations. To quantify potential uncertainties associated with forecasts, this paper implements a neural network (NN)-based method for the construction of prediction intervals (PIs). A newly introduced method, called lower upper bound estimation (LUBE), is applied and extended to develop PIs using NN models. A new problem formulation is proposed, which translates the primary multiobjective problem into a constrained single-objective problem. Compared with the cost function, this new formulation is closer to the primary problem and has fewer parameters. Particle swarm optimization (PSO) integrated with the mutation operator is used to solve the problem. Electrical demands from Singapore and New South Wales (Australia), as well as wind power generation from Capital Wind Farm, are used to validate the PSO-based LUBE method. Comparative results show that the proposed method can construct higher quality PIs for load and wind power generation forecasts in a short time.

Load Flow and Short Circuit Analysis of the Class III Power System of HANARO

Energy Technology Data Exchange (ETDEWEB)

Kim, H. K.; Jung, H. S

2005-12-15

The planning, design, and operation of electric power system require engineering studies to assist in the evaluation of the system performance, reliability, safety and economics. The Class III power of HANARO supplies power for not only HANARO but also RIPF and IMEF. The starting current of most ac motors is five to ten times normal full load current. The loads of the Class III power are connected in consecutive orders at an interval for 10 seconds to avoid excessive voltage drop. This technical report deals with the load flow study and motor starting study for the Class III power of HANARO using ETAP(Electrical Transient Analyzer Program) to verify the capacity of the diesel generator. Short-circuit studies are done to determine the magnitude of the prospective currents flowing throughout the power system at various time intervals after a fault occurs. Short-circuit studies can be performed at the planning stage in order to help finalize the system layout, determine voltage levels, and size cables, transformers, and conductors. From this study, we verify the short circuit current capacity of air circuit breaker(ACB) and automatic transfer switch(ATS) of the Class III power.

Detailed partial load investigation of a thermal energy storage concept for solar thermal power plants with direct steam generation

Science.gov (United States)

Seitz, M.; Hübner, S.; Johnson, M.

2016-05-01

Direct steam generation enables the implementation of a higher steam temperature for parabolic trough concentrated solar power plants. This leads to much better cycle efficiencies and lower electricity generating costs. For a flexible and more economic operation of such a power plant, it is necessary to develop thermal energy storage systems for the extension of the production time of the power plant. In the case of steam as the heat transfer fluid, it is important to use a storage material that uses latent heat for the storage process. This leads to a minimum of exergy losses during the storage process. In the case of a concentrating solar power plant, superheated steam is needed during the discharging process. This steam cannot be superheated by the latent heat storage system. Therefore, a sensible molten salt storage system is used for this task. In contrast to the state-of-the-art thermal energy storages within the concentrating solar power area of application, a storage system for a direct steam generation plant consists of a latent and a sensible storage part. Thus far, no partial load behaviors of sensible and latent heat storage systems have been analyzed in detail. In this work, an optimized fin structure was developed in order to minimize the costs of the latent heat storage. A complete system simulation of the power plant process, including the solar field, power block and sensible and latent heat energy storage calculates the interaction between the solar field, the power block and the thermal energy storage system.

Load-Following Voltage Controller Design for a Static Space Nuclear Power System

International Nuclear Information System (INIS)

Parlos, Alexander G.; Onbasioglou, Fetiye O.; Metzger, John D.

2000-01-01

The reliability of static space nuclear power systems (SNPSs) could be improved through the use of backup devices in addition to shunt regulators, as currently proposed for load following. Shunt regulator failure leading to reactor shutdown is possible, as is the possible need to deliver somewhat higher power level to the load than originally expected. A backup system is proposed in SNPSs to eliminate the possibility of a single-point failure in the shunt regulators and to increase the overall system power delivery capability despite changing mission needs and component characteristics. The objective of this paper is to demonstrate the feasibility of such a backup device for voltage regulation in static SNPSs that is capable of overcoming system variations resulting from operation at different power levels. A dynamic compensator is designed using the Linear Quadratic Gaussian with Loop Transfer Recovery method. The resulting compensators are gain scheduled using the SNPS electric power as the scheduling variable, resulting in a nonlinear compensator. The performance of the gain-scheduled compensator is investigated extensively using an SNPS simulator. The simulations demonstrate the effects of the fuel temperature reactivity coefficient variations on the load-following capabilities of the SNPS. Robustness analysis results demonstrate that the proposed controller exhibits significant operational flexibility, and it can be considered for long-term space mission requiring significant levels of autonomy

The relationship between loads and power of a rotor and an actuator disc

International Nuclear Information System (INIS)

Van Kuik, Gijs A M

2014-01-01

Most state of the art rotor design methods are based on the actuator disc theory developed about one century ago. The actuator disc is an axisymmetric permeable surface carrying a load that represents the load on a real rotor with a finite number of blades N. However, the mathematics of the transition from a real rotor load to an axisymmetrically loaded disc is not yet presented in literature. By formulating an actuator disc equation of motion in which the Bernoulli constant H is expressed in kinematical terms, a comparison of the power conversion and load on the disc and rotor is possible. For both the converted power is expressed as a change of angular momentum times rotational speed. The limits for N → ∞ while the chord c → 0, the rotational speed Ω → ∞, the load F becoming uniform by ∂F/∂r → 0 and the thickness ε → 0 confirm that the classical disc represents the rotor with an infinite number of blades. Furthermore, the expressions for the blade load are compared to the expressions in current design and analysis tools. The latter do not include the load on chord-wise vorticity. Including this is expected to give a better modelling of the tip and root flow

The relationship between loads and power of a rotor and an actuator disc

Science.gov (United States)

van Kuik, Gijs A. M.

2014-12-01

Most state of the art rotor design methods are based on the actuator disc theory developed about one century ago. The actuator disc is an axisymmetric permeable surface carrying a load that represents the load on a real rotor with a finite number of blades N. However, the mathematics of the transition from a real rotor load to an axisymmetrically loaded disc is not yet presented in literature. By formulating an actuator disc equation of motion in which the Bernoulli constant H is expressed in kinematical terms, a comparison of the power conversion and load on the disc and rotor is possible. For both the converted power is expressed as a change of angular momentum times rotational speed. The limits for N → ∞ while the chord c → 0, the rotational speed Ω → ∞, the load F becoming uniform by ∂F/∂r → 0 and the thickness epsilon → 0 confirm that the classical disc represents the rotor with an infinite number of blades. Furthermore, the expressions for the blade load are compared to the expressions in current design and analysis tools. The latter do not include the load on chord-wise vorticity. Including this is expected to give a better modelling of the tip and root flow.

Evaluation of reactivity and Xe behavior during daily load following operation

International Nuclear Information System (INIS)

Sakamoto, Yasunori; Araki, Tsuneyasu; Yamamoto, Fumiaki

1992-01-01

A boiling water reactor (BWR) has an excellent load following capability provided by a core flow control, which is used for changing a reactor power level and for compensating the subsequent Xe concentration change. The core characteristics during load following operations are investigated in detail, using our reactor core simulator. Comparisons of changes of the Doppler reactivity, the void reactivity and the Xe reactivity during transients are performed. Also the features of Xe transient during load following operations are shown. It has been shown that the core flow change required to compensate the Xe reactivity change produces much greater change of the void reactivity than that required for power level changes, and that the resulting local power change in the lower part of the core is greater than that in the upper part, because the Xe concentration change in the lower part is hardly compensated by the core flow control. Also the effects of power level changes, cycle patterns, and initial concentration of Xe and I on the Xe transient behavior have been investigated. (author)

Load characteristics of wireless power transfer system with different resonant types and resonator numbers

Directory of Open Access Journals (Sweden)

Yiming Zhang

2017-05-01

Full Text Available Wireless Power Transfer (WPT has been the research focus and applied in many fields. Normally power is transferred wirelessly to charge the battery, which requires specific load characteristics. The load characteristics are essential for the design and operation of the WPT system. This paper investigates the load characteristics of the WPT system with different resonant types and resonator numbers. It is found that in a WPT system with series or LCL resonance under a constant voltage source, the load characteristic is determined by the number of inductors. Even number of inductors results in a constant current characteristic and odd number constant voltage characteristic. Calculations, simulations, and experiments verify the analysis.

Automatic Control of Reactor Temperature and Power Distribution for a Daily Load following Operation

Energy Technology Data Exchange (ETDEWEB)

Yu, Keuk Jong; Kim, Han Gon [Korea Hydro and Nuclear Power Institute, Daejeon (Korea, Republic of)

2010-10-15

An automatic control method of reactor power and power distribution was developed for a daily load following operation of APR1400. This method used a model predictive control (MPC) methodology having second-order plant data. And it utilized a reactor power ratio and axial shape index as control variables. However, the reactor regulating system of APR1400 is operated by the difference between the average temperature of the reactor core and the reference temperature, which is proportional to the turbine load. Thus, this paper reports on the model predictive control methodology using fourth-order plant data and a reactor temperature instead of the reactor power shape. The purpose of this study is to develop a revised automatic controller and analyze the behavior of the nuclear reactor temperature (Tavg) and the axial shape index (ASI) using the MPC method during a daily load following operation

Concentration Measurements of Suspended Load using ADV with Influence of the Particle Size

Science.gov (United States)

Schwarzwälder, Kordula

2017-04-01

ADV backscatter data can be used under certain conditions to gain information about the concentrations of suspended loads. This was shown in many studies before (Fugate and Friedrichs 2002; Chanson et al 2008; Ha et al. 2009). This paper reports on a pre-study to investigate the influence of particle size on concentration measurements for suspended sediment load with ADV. The study was conducted in a flume in the Oskar-von-Miller-Institute using fresh water from a river including the natural suspended load. The ADV used in the experiments was a Vectrino Profiler (Nortek). In addition water samples were taken for TSS and TOC. For the measurements a surge was generated in the flume to ensure that also particles of larger size will be present in the water phase. The measurements and samples were taken during the whole surge event. Therefore we were able to find a good correlation between the backscatter data of the ADV and the TSS as well as TOC results. For the decreasing part of the flow event the concentration of TOC in the suspended load of the water phase is decreasing much slower than the TSS and results in a damped decrease of the backscatter values. This means that the results for concentration measurements might be slightly influenced by the size of the particles. Further evaluations of measurements conducted with a LISST SL (Sequoia) will be investigated to show the trend of the particle sizes during this process and fortify this result. David C. Fugate, Carl T. Friedrichs, Determining concentration and fall velocity of estuarine particle populations using ADV, OBS and LISST, Continental Shelf Research, Volume 22, Issues 11-13, 2002 H.K. Ha, W.-Y. Hsu, J.P.-Y. Maa, Y.Y. Shao, C.W. Holland, Using ADV backscatter strength for measuring suspended cohesive sediment concentration, Continental Shelf Research, Volume 29, Issue 10, 2009 Hubert Chanson, Maiko Takeuchi, Mark Trevethan, Using turbidity and acoustic backscatter intensity as surrogate measures of

Transient and steady-state tests of the space power research engine with resistive and motor loads

Science.gov (United States)

Rauch, Jeffrey S.; Kankam, M. David

1995-01-01

The NASA Lewis Research Center (LeRC) has been testing free-piston Stirling engine/linear alternators (FPSE/LA) to develop advanced power convertors for space-based electrical power generation. Tests reported herein were performed to evaluate the interaction and transient behavior of FPSE/LA-based power systems with typical user loads. Both resistive and small induction motor loads were tested with the space power research engine (SPRE) power system. Tests showed that the control system could maintain constant long term voltage and stable periodic operation over a large range of engine operating parameters and loads. Modest resistive load changes were shown to cause relatively large voltage and, therefore, piston and displacer amplitude excursions. Starting a typical small induction motor was shown to cause large and, in some cases, deleterious voltage transients. The tests identified the need for more effective controls, if FPSE/LAs are to be used for stand-alone power systems. The tests also generated a large body of transient dynamic data useful for analysis code validation.

Transient and Steady-state Tests of the Space Power Research Engine with Resistive and Motor Loads

Science.gov (United States)

Rauch, Jeffrey S.; Kankam, M. David

1995-01-01

The NASA Lewis Research Center (LeRC) has been testing free-piston Stirling engine/linear alternators (FPSE/LA) to develop advanced power convertors for space-based electrical power generation. Tests reported herein were performed to evaluate the interaction and transient behavior of FPSE/LA-based power systems with typical user loads. Both resistive and small induction motor loads were tested with the space power research engine (SPRE) power system. Tests showed that the control system could maintain constant long term voltage and stable periodic operation over a large range of engine operating parameters and loads. Modest resistive load changes were shown to cause relatively large voltage and, therefore, piston and displacer amplitude excursions. Starting a typical small induction motor was shown to cause large and, in some cases, deleterious voltage transients. The tests identified the need for more effective controls, if FPSE/LAs are to be used for stand-alone power systems. The tests also generated a large body of transient dynamic data useful for analysis code validation.

Decentralized model predictive based load frequency control in an interconnected power system

Energy Technology Data Exchange (ETDEWEB)

Mohamed, T.H., E-mail: tarekhie@yahoo.co [High Institute of Energy, South Valley University (Egypt); Bevrani, H., E-mail: bevrani@ieee.or [Dept. of Electrical Engineering and Computer Science, University of Kurdistan (Iran, Islamic Republic of); Hassan, A.A., E-mail: aahsn@yahoo.co [Faculty of Engineering, Dept. of Electrical Engineering, Minia University, Minia (Egypt); Hiyama, T., E-mail: hiyama@cs.kumamoto-u.ac.j [Dept. of Electrical Engineering and Computer Science, Kumamoto University, Kumamoto (Japan)

2011-02-15

This paper presents a new load frequency control (LFC) design using the model predictive control (MPC) technique in a multi-area power system. The MPC technique has been designed such that the effect of the uncertainty due to governor and turbine parameters variation and load disturbance is reduced. Each local area controller is designed independently such that stability of the overall closed-loop system is guaranteed. A frequency response model of multi-area power system is introduced, and physical constraints of the governors and turbines are considered. The model was employed in the MPC structures. Digital simulations for both two and three-area power systems are provided to validate the effectiveness of the proposed scheme. The results show that, with the proposed MPC technique, the overall closed-loop system performance demonstrated robustness in the face of uncertainties due to governors and turbines parameters variation and loads disturbances. A performance comparison between the proposed controller and a classical integral control scheme is carried out confirming the superiority of the proposed MPC technique.

Decentralized model predictive based load frequency control in an interconnected power system

International Nuclear Information System (INIS)

Mohamed, T.H.; Bevrani, H.; Hassan, A.A.; Hiyama, T.

2011-01-01

This paper presents a new load frequency control (LFC) design using the model predictive control (MPC) technique in a multi-area power system. The MPC technique has been designed such that the effect of the uncertainty due to governor and turbine parameters variation and load disturbance is reduced. Each local area controller is designed independently such that stability of the overall closed-loop system is guaranteed. A frequency response model of multi-area power system is introduced, and physical constraints of the governors and turbines are considered. The model was employed in the MPC structures. Digital simulations for both two and three-area power systems are provided to validate the effectiveness of the proposed scheme. The results show that, with the proposed MPC technique, the overall closed-loop system performance demonstrated robustness in the face of uncertainties due to governors and turbines parameters variation and loads disturbances. A performance comparison between the proposed controller and a classical integral control scheme is carried out confirming the superiority of the proposed MPC technique.

After-hours power status of office equipment and energy use of miscellaneous plug-load equipment

Energy Technology Data Exchange (ETDEWEB)

Roberson, Judy A.; Webber, Carrie A.; McWhinney, Marla C.; Brown, Richard E.; Pinckard, Marageret J.; Busch, John F.

2004-05-27

This research was conducted in support of two branches of the EPA ENERGY STAR program, whose overall goal is to reduce, through voluntary market-based means, the amount of carbon dioxide emitted in the U.S. The primary objective was to collect data for the ENERGY STAR Office Equipment program on the after-hours power state of computers, monitors, printers, copiers, scanners, fax machines, and multi-function devices. We also collected data for the ENERGY STAR Commercial Buildings branch on the types and amounts of miscellaneous plug-load equipment, a significant and growing end use that is not usually accounted for by building energy managers. For most types of miscellaneous equipment, we also estimated typical unit energy consumption in order to estimate total energy consumption of the miscellaneous devices within our sample. This data set is the first of its kind that we know of, and is an important first step in characterizing miscellaneous plug loads in commercial buildings. The main purpose of this study is to supplement and update previous data we collected on the extent to which electronic office equipment is turned off or automatically enters a low power state when not in active use. In addition, it provides data on numbers and types of office equipment, and helps identify trends in office equipment usage patterns. These data improve our estimates of typical unit energy consumption and savings for each equipment type, and enables the ENERGY STAR Office Equipment program to focus future effort on products with the highest energy savings potential. This study expands our previous sample of office buildings in California and Washington DC to include education and health care facilities, and buildings in other states. We report data from sixteen commercial buildings in California, Georgia, and Pennsylvania: four education buildings, two medical buildings, two large offices (> 500 employees each), three medium offices (50-500 employees each), and five small

Computer-aided load monitoring system for nuclear power plant steel framing structures

International Nuclear Information System (INIS)

Skaczylo, A.T.; Fung, S-J; Hooks, R.W.

1984-01-01

The design of nuclear power plant steel framing structures is a long and involved process. It is often complicated by numerous changes in design loads as a result of additions, deletions and modifications of HVAC hangers, cable tray hangers, electric conduit hangers, and small bore and large bore mechanical component supports. Manual tracking of load changes of thousands of supports and their impact to the structural steel design adequacy is very time-consuming and is susceptible to errors. This paper presents a computer-aided load monitoring system using the latest technology of data base management and interactive computer software. By linking the data base to analysis and investigation computer programs, the engineer has a very powerful tool to monitor not only the load revisions but also their impact on the steel structural floor framing members and connections. Links to reporting programs allow quick information retrieval in the form of comprehensive reports. Drawing programs extract data from the data base to draw hanger load system drawings on a computer-aided drafting system. These capabilities allow engineers to minimize modifications by strategically locating new hangers or rearranging auxiliary steel configuration

Force-directed design of a voluntary closing hand prosthesis

NARCIS (Netherlands)

De Visser, H.; Herder, J.L.

2000-01-01

This paper presents the design of a body-powered voluntary closing prosthetic hand. It is argued that the movement of the fingers before establishing a grip is much less relevant for good control of the object held than the distribution of forces once the object has been contacted. Based on this

Performance assessment of a power loaded supercapacitor based on manufacturer data

International Nuclear Information System (INIS)

Mellincovsky, Martin; Kuperman, Alon; Lerman, Chaim; Aharon, Ilan; Reichbach, Noam; Geula, Gal; Nakash, Ronen

2013-01-01

Highlights: • Analytic performance of a power loaded supercapacitor is derived. • Power and energy capabilities based on manufacturer data are obtained. • Power limitations based on depth of discharge are presented. - Abstract: Analytical derivation of constant power loaded supercapacitor behavior is presented in the paper. Simple RC model based on manufacturer datasheet extracted parameters is employed. Power and energy related figures of merit are obtained from the derived expressions and compared to the datasheet provided values. It is revealed that some of the performance characteristics provided in most of the datasheets are theoretical and cannot be achieved in practice. The process of a realistic Ragone plot derivation based on the proposed method is described in the paper as well. It is shown that the lower limit of supercapacitor voltage imposes certain limits on power and energy capabilities of the device. Extended simulation and experimental results are provided in order to reinforce the proposed method and justify the selected RC model for describing the supercapacitor performance. By appropriate comparison of simulations and experiments it is proven that the selected model, while being oversimplified and low order, may be used to predict supercapacitor behavior with reasonable accuracy to perform at least an initial design

FY 1998 annual report on the demonstration tests for establishing load concentration controlling systems. Survey on safety of commercial systems; Fuka shuchu seigyo system kakuritsu jissho shiken 1998 nendo kenkyu hokokusho. Jjitsuyo system anzensei chosa

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-03-01

The demonstration tests are being conducted for establishing load concentration controlling systems, which directly or indirectly control load devices in residential power consumers or the like from a power supplier, as one of the DSM measures. This project is aimed at survey on the systems which support general residential consumers or the like to adequately control loads indirectly, and at clarification of technical essentials the system should have when it is actually put in service and the safety rules to be observed, thereby contributing eventual commercialization of the load concentration controlling systems. The field test results indicate that functions of a monitor set in a domestic consumer can be well operated even by inexperienced persons in handling machines, when they have some experiences. Reliability of a monitoring/controlling device, set in a domestic consumer on a trial basis, can be secured effectively by addition of an LC circuit and changing the modulation mode to FSK. The devices developed on a trial basis are found to be well serviceable for the demonstration tests. The best method for communication with the monitoring/controlling device for electric appliances in a domestic consumer is communication via a power transmission line. (NEDO)

The characterization of secondary lithium-ion battery degradation when operating complex, ultra-high power pulsed loads

Science.gov (United States)

Wong, Derek N.

The US Navy is actively developing all electric fleets, raising serious questions about what is required of onboard power supplies in order to properly power the ship's electrical systems. This is especially relevant when choosing a viable power source to drive high power propulsion and electric weapon systems in addition to the conventional loads deployed aboard these types of vessels. Especially when high pulsed power loads are supplied, the issue of maintaining power quality becomes important and increasingly complex. Conventionally, a vessel's electrical power is generated using gas turbine or diesel driven motor-generator sets that are very inefficient when they are used outside of their most efficient load condition. What this means is that if the generator is not being utilized continuously at its most efficient load capacity, the quality of the output power may also be effected and fall outside of the acceptable power quality limits imposed through military standards. As a solution to this potential problem, the Navy has proposed using electrochemical storage devices since they are able to buffer conventional generators when the load is operating below the generator's most efficient power level or able to efficiently augment a generator when the load is operating in excess of the generator's most efficient power rating. Specifically, the US Navy is interested in using commercial off-the-shelf (COTS) lithium-ion batteries within an intelligently controlled energy storage module that could act as either a prime power supply for on-board pulsed power systems or as a backup generator to other shipboard power systems. Due to the unique load profile of high-rate pulsed power systems, the implementation of lithium-ion batteries within these complex systems requires them to be operated at very high rates and the effects these things have on cell degradation has been an area of focus. There is very little published research into the effects that high power transient

Concentrated solar power generation using solar receivers

Science.gov (United States)

Anderson, Bruce N.; Treece, William Dean; Brown, Dan; Bennhold, Florian; Hilgert, Christoph

2017-08-08

Inventive concentrated solar power systems using solar receivers, and related devices and methods, are generally described. Low pressure solar receivers are provided that function to convert solar radiation energy to thermal energy of a working fluid, e.g., a working fluid of a power generation or thermal storage system. In some embodiments, low pressure solar receivers are provided herein that are useful in conjunction with gas turbine based power generation systems.

Selenium concentrations and loads from coal mining operations in the Elk River Watershed, Southeastern BC : 2004-2009

International Nuclear Information System (INIS)

Paine, M.; Orr, P.; Franklin, W.; Fraser, C.

2010-01-01

This presentation reported on a study in which selenium concentrations were measured at 27 receiving and 40 discharge water stations in British Columbia's Elk River watershed, where Teck Coal Ltd. operates 5 coal mines. Monthly measurements were taken in the Elk River and its major tributaries from 2004 to 2009 to evaluate trends for selenium concentrations in receiving waters, and for concentrations and loads at selected discharges. Selenium concentrations were found to be much higher than background levels of 1 g/L in areas downstream of mine discharges in the Fording River, Line Creek, Michel Creek and in the lower Elk River below its confluence with the Fording River. Concentrations increased considerably over time in the Fording and lower Elk Rivers, and in Line Creek. Most of the selenium loads discharged to the Elk River and its tributaries were found to originate from less than 10 major sources. Concentrations increased with time at most major sources. At some sources, selenium loads increased with time, but decreased at others. The increase in concentrations in the lower Elk River and at several major sources from 2007 to 2009 may be attributed in part to a decrease in flow. Options for reducing selenium loads discharged to downstream receiving waters are being investigated by the mines.

Modeling and simulation of stand-alone hybrid power system with fuzzy MPPT for remote load application

Directory of Open Access Journals (Sweden)

Bogaraj T.

2015-09-01

Full Text Available Many parts of remote locations in the world are not electrified even in this Advanced Technology Era. To provide electricity in such remote places renewable hybrid energy systems are very much suitable. In this paper PV/Wind/Battery Hybrid Power System (HPS is considered to provide an economical and sustainable power to a remote load. HPS can supply the maximum power to the load at a particular operating point which is generally called as Maximum Power Point (MPP. Fuzzy Logic based MPPT (FLMPPT control method has been implemented for both Solar and Wind Power Systems. FLMPPT control technique is implemented to generate the optimal reference voltage for the first stage of DC-DC Boost converter in both the PV and Wind energy system. The HPS is tested with variable solar irradiation, temperature, and wind speed. The FLMPPT method is compared with P&O MPPT method. The proposed method provides a good maximum power operation of the hybrid system at all operating conditions. In order to combine both sources, the DC bus voltage is made constant by employing PI Controllers for the second stage of DC-DC Buck-Boost converter in both Solar and Wind Power Systems. Battery Bank is used to store excess power from Renewable Energy Sources (RES and to provide continuous power to load when the RES power is less than load power. A SPWM inverter is designed to convert DC power into AC to supply three phase load. An LC filter is also used at the output of inverter to get sinusoidal current from the PWM inverter. The entire system was modeled and simulated in Matlab/Simulink Environment. The results presented show the validation of the HPS design.

Forecasting loads and prices in competitive power markets

International Nuclear Information System (INIS)

Bunn, D.W.

2000-01-01

This paper provides a review of some of the main methodological issues and techniques which have become innovative in addressing the problem of forecasting daily loads and prices in the new competitive power markets. Particular emphasis is placed upon computationally intensive methods, including variable segmentation, multiple modeling, combinations, and neural networks for forecasting the demand side, and strategic simulation using artificial agents for the supply side

Load following generation in nuclear power plants by latent thermal energy storage

International Nuclear Information System (INIS)

Abe, Yoshiyuki; Takahashi, Yoshio; Kamimoto, Masayuki; Sakamoto, Ryuji; Kanari, Katsuhiko; Ozawa, Takeo

1985-01-01

The recent increase in nuclear power plants and the growing difference between peak and off-peak demands imperatively need load following generation in nuclear power plants to meet the time-variant demands. One possible way to resolve the problem is, obviously, a prompt reaction conrol in the reactors. Alternatively, energy storage gives another sophisticated path to make load following generation in more effective manner. Latent thermal energy storage enjoys high storage density and allows thermal extraction at nearly constant temperature, i.e. phase change temperature. The present report is an attempt to evaluate the feasibility of load following electric power generation in nuclear plants (actually Pressurized Water Reactors) by latent thermal energy storage. In this concept, the excess thermal energy in the off-peak period is stored in molten salt latent thermal energy storage unit, and additional power output is generated in auxiliary generator in the peak demand duration using the stored thermal energy. The present evaluation gives encouraging results and shows the primary subject to be taken up at first is the compatibility of candidate storage materials with inexpensive structural metal materials. Chapter 1 denotes the background of the present report, and Chapter 2 reviews the previous studies on the peak load coverage by thermal energy storage. To figure out the concept of the storage systems, present power plant systems and possible constitution of storage systems are briefly shown in Chapter 3. The details of the evaluation of the candidate storage media, and the compilation of the materials' properties are presented in Chapter 4. In Chapter 5, the concept of the storage systems is depicted, and the economical feasibility of the systems is evaluated. The concluding remarks are summarized in Chapter 6. (author)

Voluntary agreements in environmental policy

International Nuclear Information System (INIS)

Torvanger, Asbjoern

2001-01-01

A typically voluntary agreement is signed between the authorities and an industrial sector in order to reduce the emission of environmentally harmful substances. There are many different types of agreements. Voluntary agreements are not strictly voluntary, since in the background there is often some kind of ''threat'' about taxation or fees if the industry is unwilling to cooperate. This type of agreements has become popular in many OECD countries during the last decades. In Norway there are only a few agreements of this type. Experience with the use of voluntary agreements as well as research show that they are less cost-effective than market-based instruments such as taxes and quota systems. If there are great restrictions on the use of taxes and quota systems because of information- or measurement problems, or because these instruments are not politically acceptable, then voluntary agreements may be an interesting alternative. Thus, voluntary agreements are best used as a supplement to other instruments in some niche areas of the environmental policy. In some cases, voluntary agreements may be used between two countries or at a regional level, for example within the EU

Load frequency control of an asynchronous restructured power system

African Journals Online (AJOL)

This paper presents the analysis of load frequency control (LFC) of a two-area restructured power system interconnected via parallel ac/dc transmission links. Simulation results show that the limitations of PI controller can be overcome by including Fuzzy logic concept and thereby the dynamic performance can be improved ...

Effects of Different Relative Loads on Power Performance During the Ballistic Push-up.

Science.gov (United States)

Wang, Ran; Hoffman, Jay R; Sadres, Eliahu; Bartolomei, Sandro; Muddle, Tyler W D; Fukuda, David H; Stout, Jeffrey R

2017-12-01

Wang, R, Hoffman, JR, Sadres, E, Bartolomei, S, Muddle, TWD, Fukuda, DH, and Stout, JR. Effects of different relative loads on power performance during the ballistic push-up. J Strength Cond Res 31(12): 3411-3416, 2017-The purpose of this investigation was to examine the effect of load on force and power performance during a ballistic push-up. Sixty (24.5 ± 4.3 years, 1.75 ± 0.07 m, and 80.8 ± 13.5 kg) recreationally active men who participated in this investigation completed all testing and were included in the data analysis. All participants were required to perform a 1 repetition maximum bench press, and ballistic push-ups without external load (T1), with 10% (T2) and 20% (T3) of their body mass. Ballistic push-ups during T2 and T3 were performed using a weight loaded vest. Peak and mean force, power, as well as net impulse and flight time were determined for each ballistic push-up. Peak and mean force were both significantly greater (p ballistic push-up, regardless of the participants' level of strength.

Part-load performance of a high temperature Kalina cycle

International Nuclear Information System (INIS)

Modi, Anish; Andreasen, Jesper Graa; Kærn, Martin Ryhl; Haglind, Fredrik

2015-01-01

Highlights: • Detailed algorithm to solve high temperature Kalina cycle in part load. • A central receiver concentrating solar power plant with direct vapour generation considered as case study. • Part-load performance curves and fitted equations presented. - Abstract: The Kalina cycle has recently seen increased interest as an alternative to the conventional steam Rankine cycle. The cycle has been studied for use with both low and high temperature applications such as geothermal power plants, ocean thermal energy conversion, waste heat recovery, gas turbine bottoming cycle, and solar power plants. The high temperature cycle layouts are inherently more complex than the low temperature layouts due to the presence of a distillation-condensation subsystem, three pressure levels, and several heat exchangers. This paper presents a detailed approach to solve the Kalina cycle in part-load operating conditions for high temperature (a turbine inlet temperature of 500 °C) and high pressure (100 bar) applications. A central receiver concentrating solar power plant with direct vapour generation is considered as a case study where the part-load conditions are simulated by changing the solar heat input to the receiver. Compared with the steam Rankine cycle, the Kalina cycle has an additional degree of freedom in terms of the ammonia mass fraction which can be varied in order to maximize the part-load efficiency of the cycle. The results include the part-load curves for various turbine inlet ammonia mass fractions and the fitted equations for these curves.

Power flow control strategy in distribution network for dc type distributed energy resource at load bus

International Nuclear Information System (INIS)

Hanif, A.; Choudhry, M.A.

2013-01-01

This research work presents a feed forward power flow control strategy in the secondary distribution network working in parallel with a DC type distributed energy resource (DER) unit with SPWM-IGBT Voltage Source Converter (VSC). The developed control strategy enables the VSC to be used as power flow controller at the load bus in the presence of utility supply. Due to the investigated control strategy, power flow control from distributed energy resource (DER) to common load bus is such that power flows to the load without facing any power quality problem. The technique has an added advantage of controlling power flow without having a dedicated power flow controller. The SPWM-IGBT VSC is serving the purpose of dc-ac converter as well as power flow controller. Simulations for a test system using proposed power flow control strategy are carried out using SimPower Systems toolbox of MATLAB at the rate and Simulink at the rate. The results show that a reliable, effective and efficient operation of DC type DER unit in coordination with main utility network can be achieved. (author)

40 CFR 86.1772-99 - Road load power, test weight, and inertia weight class determination.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 19 2010-07-01 2010-07-01 false Road load power, test weight, and inertia weight class determination. 86.1772-99 Section 86.1772-99 Protection of Environment ENVIRONMENTAL... for Light-Duty Vehicles and Light-Duty Trucks § 86.1772-99 Road load power, test weight, and inertia...

Partial thorium loading in the initial core of Kakrapar atomic power reactor

International Nuclear Information System (INIS)

Balakrishnan, M.R.

1993-01-01

The first unit of Kakrapar nuclear power station has gone critical with some thorium oxide fuel bundles loaded in its core. The thorium helps to flatten the power by reducing neutron flux in the centre of the reactor. However, the placing of the thorium had to be planned with care, because if the neutron flux at a point where a safety rod is located is depressed, the reactivity worth of the safety rod gets reduced. Using a dynamic programing approach, the Reactor Engineering Division of Bhabha Atomic Research Centre worked out a satisfactory configuration for loading the thorium bundles

Searching for the majority: algorithms of voluntary control.

Directory of Open Access Journals (Sweden)

Jin Fan

Full Text Available Voluntary control of information processing is crucial to allocate resources and prioritize the processes that are most important under a given situation; the algorithms underlying such control, however, are often not clear. We investigated possible algorithms of control for the performance of the majority function, in which participants searched for and identified one of two alternative categories (left or right pointing arrows as composing the majority in each stimulus set. We manipulated the amount (set size of 1, 3, and 5 and content (ratio of left and right pointing arrows within a set of the inputs to test competing hypotheses regarding mental operations for information processing. Using a novel measure based on computational load, we found that reaction time was best predicted by a grouping search algorithm as compared to alternative algorithms (i.e., exhaustive or self-terminating search. The grouping search algorithm involves sampling and resampling of the inputs before a decision is reached. These findings highlight the importance of investigating the implications of voluntary control via algorithms of mental operations.

Voluntary Service System (VSS)

Data.gov (United States)

Department of Veterans Affairs — Voluntary Service System (VSS) is a national-level application which replaced the site-based Voluntary Timekeeping System (VTK). VTK was used for many years at the...

A Beacon Transmission Power Control Algorithm Based on Wireless Channel Load Forecasting in VANETs.

Science.gov (United States)

Mo, Yuanfu; Yu, Dexin; Song, Jun; Zheng, Kun; Guo, Yajuan

2015-01-01

In a vehicular ad hoc network (VANET), the periodic exchange of single-hop status information broadcasts (beacon frames) produces channel loading, which causes channel congestion and induces information conflict problems. To guarantee fairness in beacon transmissions from each node and maximum network connectivity, adjustment of the beacon transmission power is an effective method for reducing and preventing channel congestion. In this study, the primary factors that influence wireless channel loading are selected to construct the KF-BCLF, which is a channel load forecasting algorithm based on a recursive Kalman filter and employs multiple regression equation. By pre-adjusting the transmission power based on the forecasted channel load, the channel load was kept within a predefined range; therefore, channel congestion was prevented. Based on this method, the CLF-BTPC, which is a transmission power control algorithm, is proposed. To verify KF-BCLF algorithm, a traffic survey method that involved the collection of floating car data along a major traffic road in Changchun City is employed. By comparing this forecast with the measured channel loads, the proposed KF-BCLF algorithm was proven to be effective. In addition, the CLF-BTPC algorithm is verified by simulating a section of eight-lane highway and a signal-controlled urban intersection. The results of the two verification process indicate that this distributed CLF-BTPC algorithm can effectively control channel load, prevent channel congestion, and enhance the stability and robustness of wireless beacon transmission in a vehicular network.

A Beacon Transmission Power Control Algorithm Based on Wireless Channel Load Forecasting in VANETs.

Directory of Open Access Journals (Sweden)

Yuanfu Mo

Full Text Available In a vehicular ad hoc network (VANET, the periodic exchange of single-hop status information broadcasts (beacon frames produces channel loading, which causes channel congestion and induces information conflict problems. To guarantee fairness in beacon transmissions from each node and maximum network connectivity, adjustment of the beacon transmission power is an effective method for reducing and preventing channel congestion. In this study, the primary factors that influence wireless channel loading are selected to construct the KF-BCLF, which is a channel load forecasting algorithm based on a recursive Kalman filter and employs multiple regression equation. By pre-adjusting the transmission power based on the forecasted channel load, the channel load was kept within a predefined range; therefore, channel congestion was prevented. Based on this method, the CLF-BTPC, which is a transmission power control algorithm, is proposed. To verify KF-BCLF algorithm, a traffic survey method that involved the collection of floating car data along a major traffic road in Changchun City is employed. By comparing this forecast with the measured channel loads, the proposed KF-BCLF algorithm was proven to be effective. In addition, the CLF-BTPC algorithm is verified by simulating a section of eight-lane highway and a signal-controlled urban intersection. The results of the two verification process indicate that this distributed CLF-BTPC algorithm can effectively control channel load, prevent channel congestion, and enhance the stability and robustness of wireless beacon transmission in a vehicular network.

Market power in electricity markets: Beyond concentration measures

International Nuclear Information System (INIS)

Borenstein, S.; Bushnell, J.; Knittel, C.R.

1999-01-01

The wave of electricity market restructuring both within the US and abroad has brought the issue of horizontal market power to the forefront of energy policy. Traditionally, estimation and prediction of market power has relied heavily on concentration measures. In this paper, the authors discuss the weaknesses of concentration measures as a viable measure of market power in the electricity industry, and they propose an alternative method based on market simulations that take advantage of existing plant level data. The authors discuss results from previous studies they have performed, and present new results that allow for the detection of threshold demand levels where market power is likely to be a problem. In addition, the authors analyze the impact of that recent divestitures in the California electricity market will have on estimated market power. They close with a discussion of the policy implications of the results

Balancing Power Absorption and Fatigue Loads in Irregular Waves for an Oscillating Surge Wave Energy Converter: Preprint

Energy Technology Data Exchange (ETDEWEB)

Tom, Nathan M.; Yu, Yi-Hsiang; Wright, Alan D.; Lawson, Michael

2016-06-01

The aim of this paper is to describe how to control the power-to-load ratio of a novel wave energy converter (WEC) in irregular waves. The novel WEC that is being developed at the National Renewable Energy Laboratory combines an oscillating surge wave energy converter (OSWEC) with control surfaces as part of the structure; however, this work only considers one fixed geometric configuration. This work extends the optimal control problem so as to not solely maximize the time-averaged power, but to also consider the power-take-off (PTO) torque and foundation forces that arise because of WEC motion. The objective function of the controller will include competing terms that force the controller to balance power capture with structural loading. Separate penalty weights were placed on the surge-foundation force and PTO torque magnitude, which allows the controller to be tuned to emphasize either power absorption or load shedding. Results of this study found that, with proper selection of penalty weights, gains in time-averaged power would exceed the gains in structural loading while minimizing the reactive power requirement.

Optimization of hybrid power system composed of SMES and flywheel MG for large pulsed load

International Nuclear Information System (INIS)

Niiyama, K.; Yagai, T.; Tsuda, M.; Hamajima, T.

2008-01-01

A superconducting magnetic storage system (SMES) has some advantages such as rapid large power response and high storage efficiency which are superior to other energy storage systems. A flywheel motor generator (FWMG) has large scaled capacity and high reliability, and hence is broadly utilized for a large pulsed load, while it has comparatively low storage efficiency due to high mechanical loss compared with SMES. A fusion power plant such as International Thermo-Nuclear Experimental Reactor (ITER) requires a large and long pulsed load which causes a frequency deviation in a utility power system. In order to keep the frequency within an allowable deviation, we propose a hybrid power system for the pulsed load, which equips the SMES and the FWMG with the utility power system. We evaluate installation cost and frequency control performance of three power systems combined with energy storage devices; (i) SMES with the utility power, (ii) FWMG with the utility power, (iii) both SMES and FWMG with the utility power. The first power system has excellent frequency power control performance but its installation cost is high. The second system has inferior frequency control performance but its installation cost is the lowest. The third system has good frequency control performance and its installation cost is attained lower than the first power system by adjusting the ratio between SMES and FWMG

An electrical betweenness approach for vulnerability assessment of power grids considering the capacity of generators and load

Science.gov (United States)

Wang, Kai; Zhang, Bu-han; Zhang, Zhe; Yin, Xiang-gen; Wang, Bo

2011-11-01

Most existing research on the vulnerability of power grids based on complex networks ignores the electrical characteristics and the capacity of generators and load. In this paper, the electrical betweenness is defined by considering the maximal demand of load and the capacity of generators in power grids. The loss of load, which reflects the ability of power grids to provide sufficient power to customers, is introduced to measure the vulnerability together with the size of the largest cluster. The simulation results of the IEEE-118 bus system and the Central China Power Grid show that the cumulative distributions of node electrical betweenness follow a power-law and that the nodes with high electrical betweenness play critical roles in both topological structure and power transmission of power grids. The results prove that the model proposed in this paper is effective for analyzing the vulnerability of power grids.

Optimization of disk generator performance for base-load power plant systems applications

International Nuclear Information System (INIS)

Teare, J.D.; Loubsky, W.J.; Lytle, J.K.; Louis, J.F.

1980-01-01

Disk generators for use in base-load MHD power plants are examined for both open-cycle and closed-cycle operating modes. The OCD cases are compared with PSPEC results for a linear channel; enthalpy extractions up to 23% with 71% isentropic efficiency are achievable with generator inlet conditions similar to those used in PSPEC, thus confirming that the disk configuration is a viable alternative for base-load power generation. The evaluation of closed-cycle disks includes use of a simplified cycle model. High system efficiencies over a wide range of power levels are obtained for effective Hall coefficients in the range 2.3 to 4.9. Cases with higher turbulence (implying β/sub eff/ less than or equal to 2.4) yield high system efficiencies at power levels of 100 to 500 MW/sub e/. All these CCD cases compare favorably with linear channels reported in the GE ECAS study, yielding higher isentropic efficiences for a given enthalpy extraction. Power densities in the range 70 to 170 MW/m 3 appear feasible, leading to very compact generator configurations

A model of market power in electricity industries subject to peak load pricing

International Nuclear Information System (INIS)

Arellano, Maria-Soledad; Serra, Pablo

2007-01-01

This paper studies the exercise of market power in price-regulated electricity industries under peak-load pricing and merit order dispatching, but where investment decisions are taken by independent generating companies. Within this context, we show that producers can exercise market power by under-investing in base-load capacity, compared to the welfare-maximizing configuration. We also show that when there is free entry with an exogenous fixed entry cost that is later sunk, more intense competition results in higher welfare but fewer firms. (author)

Current multiplier to improved generator-to-load coupling for pulse-power generators

International Nuclear Information System (INIS)

Chuvatin, A.S.; Rudakov, L.I.; Weber, B.V.; Bayol, F.; Cadiergues, R.

2005-01-01

The circuit presented improves the coupling of existing and future pulsed power generators to physical loads. The efficiency of the proposed current multiplication scheme could theoretically exceed the values for a typical direct load-to-generator circuit. The scheme could be beneficial for use in actual applications and two examples of such applications are given [ru

Skeletal Muscle Remodeling in Response to Eccentric vs. Concentric Loading: Morphological, Molecular, and Metabolic Adaptations

Directory of Open Access Journals (Sweden)

Martino V. Franchi

2017-07-01

Full Text Available Skeletal muscle contracts either by shortening or lengthening (concentrically or eccentrically, respectively; however, the two contractions substantially differ from one another in terms of mechanisms of force generation, maximum force production and energy cost. It is generally known that eccentric actions generate greater force than isometric and concentric contractions and at a lower metabolic cost. Hence, by virtue of the greater mechanical loading involved in active lengthening, eccentric resistance training (ECC RT is assumed to produce greater hypertrophy than concentric resistance training (CON RT. Nonetheless, prevalence of either ECC RT or CON RT in inducing gains in muscle mass is still an open issue, with some studies reporting greater hypertrophy with eccentric, some with concentric and some with similar hypertrophy within both training modes. Recent observations suggest that such hypertrophic responses to lengthening vs. shortening contractions are achieved by different adaptations in muscle architecture. Whilst the changes in muscle protein synthesis in response to acute and chronic concentric and eccentric exercise bouts seem very similar, the molecular mechanisms regulating the myogenic adaptations to the two distinct loading stimuli are still incompletely understood.Thus, the present review aims to, (a critically discuss the literature on the contribution of eccentric vs. concentric loading to muscular hypertrophy and structural remodeling, and, (b clarify the molecular mechanisms that may regulate such adaptations.We conclude that, when matched for either maximum load or work, similar increase in muscle size is found between ECC and CON RT. However, such hypertrophic changes appear to be achieved through distinct structural adaptations, which may be regulated by different myogenic and molecular responses observed between lengthening and shortening contractions.

Reactor control device for controlling load of nuclear power plant

International Nuclear Information System (INIS)

Hirota, Tadakuni; Yokoyama, Terukuni; Masuda, Jiro.

1981-01-01

Purpose: To improve the load follow-up capacity of a nuclear reactor by automatically controlling the width of the not-sensing band of a control rod inserting and removing discriminator circuit. Constitution: When load control operations such as automatic load control, automatic frequency control, governor free operation and so forth are conducted, the width of a not sensing band of a control rod inserting and removing discriminator circuit is ao automatically controlled that the not sensing band width may return to ordinary value in a normal operation by avoiding the fast repetition of inserting and removing control rods by increasing the width of the insensing band if the period of a control deviation signal produced due to the variation in the load is quickly repeated and varied in correspondence to the control deviation signal. That is, a circuit for varying the insensing band of the control circuit for driving a control mechanism is provided to reduce the amount of driving the control rods in a load control operation and to reduce the strain of the power distribution of the nuclear reactor, thereby improving the load control capacity. (Yoshihara, H.)

Radial power distribution shaping within a PWR fuel assembly utilizing asymmetrically loaded gadolinia-bearing fuel pins

International Nuclear Information System (INIS)

Stone, I.Z.

1992-01-01

As in-core fuel management designs evolve to meet the demands of increasing energy output, more innovative methods are developed to maintain power peaking within acceptable thermal margin limits. In-core fuel management staff must utilize various loading pattern strategies such as cross-core movement of fuel assemblies, multibatch enrichment schemes, and burnable absorbers as the primary means of controlling the radial power distribution. The utilization of fresh asymmetrically loaded gadolinia-bearing assemblies as a fuel management tool provides an additional means of controlling the radial power distribution. At Siemens Nuclear Power Corporation (SNP), fresh fuel assemblies fabricated with asymmetrically loaded gadolinia-bearing fuel rods have been used successfully for several cycles of reactor operation. Asymmetric assemblies are neutronically modeled using the same tools and models that SNP uses to model symmetrically loaded gadolinia-bearing fuel assemblies. The CASMO-2E code is used to produce the homogenized macroscopic assembly cross sections for the nodal core simulator. Optimum fuel pin locations within the asymmetrical assembly are determined using the pin-by-pin PDQ7 assembly core model for each new assembly design. The optimum pin location is determined by the rod loading that minimizes the peak-to-average pin power

Balancing Power Absorption and Structural Loading for a Novel Fixed-Bottom Wave Energy Converter with Nonideal Power Take-Off in Regular Waves: Preprint

Energy Technology Data Exchange (ETDEWEB)

Tom, Nathan M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Yu, Yi-Hsiang [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Wright, Alan D [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-06-08

In this work, the net power delivered to the grid from a nonideal power take-off (PTO) is introduced followed by a review of the pseudo-spectral control theory. A power-to-load ratio, used to evaluate the pseudo-spectral controller performance, is discussed, and the results obtained from optimizing a multiterm objective function are compared against results obtained from maximizing the net output power to the grid. Simulation results are then presented for four different oscillating wave energy converter geometries to highlight the potential of combing both geometry and PTO control to maximize power while minimizing loads.

Distribution factors for reactive power in the presence of bilateral transactions

International Nuclear Information System (INIS)

De Tuglie, E.; Torelli, F.

2004-01-01

The twin factors of limited investment in electric transmission systems and the overexploitation of electrical resources results in an increase in the need for reactive power to support system voltage profile and to supply loads. It is reasonable to expect that generators and compensators, heavily involved in reactive support on a voluntary basis, will be remunerated for their service by market transactions. This remuneration will depend on the network topology, i.e. of buyers, sellers and reactive injection locations, on the active power exchanged and the reactive power required by loads. All these aspects are taken into account in developing a methodology based on circuit considerations. Using this approach, at a given system operating point characterised by a predefined set of transactions, reactive responsibilities can be formulated as the sum of two terms: one strictly related to transactions and the other dependent on electric network parameters. Test results demonstrate the efficacy of the proposed methodology in sharing reactive power responsibilities in a fair way among market participants. (author)

Voluntary resistance running with short distance enhances spatial memory related to hippocampal BDNF signaling.

Science.gov (United States)

Lee, Min Chul; Okamoto, Masahiro; Liu, Yu Fan; Inoue, Koshiro; Matsui, Takashi; Nogami, Haruo; Soya, Hideaki

2012-10-15

Although voluntary running has beneficial effects on hippocampal cognitive functions if done abundantly, it is still uncertain whether resistance running would be the same. For this purpose, voluntary resistance wheel running (RWR) with a load is a suitable model, since it allows increased work levels and resultant muscular adaptation in fast-twitch muscle. Here, we examined whether RWR would have potential effects on hippocampal cognitive functions with enhanced hippocampal brain-derived neurotrophic factor (BDNF), as does wheel running without a load (WR). Ten-week-old male Wistar rats were assigned randomly to sedentary (Sed), WR, and RWR (to a maximum load of 30% of body weight) groups for 4 wk. We found that in RWR, work levels increased with load, but running distance decreased by about half, which elicited muscular adaptation for fast-twitch plantaris muscle without causing any negative stress effects. Both RWR and WR led to improved spatial learning and memory as well as gene expressions of hippocampal BDNF signaling-related molecules. RWR increased hippocampal BDNF, tyrosine-related kinase B (TrkB), and cAMP response element-binding (CREB) protein levels, whereas WR increased only BDNF. With both exercise groups, there were correlations between spatial memory and BDNF protein (r = 0.41), p-CREB protein (r = 0.44), and work levels (r = 0.77). These results suggest that RWR plays a beneficial role in hippocampus-related cognitive functions associated with hippocampal BDNF signaling, even with short distances, and that work levels rather than running distance are more determinant of exercise-induced beneficial effects in wheel running with and without a load.

Effect of SMES unit in load following contract in a restructured power ...

African Journals Online (AJOL)

user

In order to achieve interconnected operation of a power system, an electric energy system must be maintained at a desired operating level characterized by nominal frequency, voltage ... path to exchange contract data as well as measurements to do load following in real-time. .... through its power conversion system (PCS).

Computing time-series suspended-sediment concentrations and loads from in-stream turbidity-sensor and streamflow data

Science.gov (United States)

Rasmussen, Patrick P.; Gray, John R.; Glysson, G. Doug; Ziegler, Andrew C.

2010-01-01

Over the last decade, use of a method for computing suspended-sediment concentration and loads using turbidity sensors—primarily nephelometry, but also optical backscatter—has proliferated. Because an in- itu turbidity sensor is capa le of measuring turbidity instantaneously, a turbidity time series can be recorded and related directly to time-varying suspended-sediment concentrations. Depending on the suspended-sediment characteristics of the measurement site, this method can be more reliable and, in many cases, a more accurate means for computing suspended-sediment concentrations and loads than traditional U.S. Geological Survey computational methods. Guidelines and procedures for estimating time s ries of suspended-sediment concentration and loading as a function of turbidity and streamflow data have been published in a U.S. Geological Survey Techniques and Methods Report, Book 3, Chapter C4. This paper is a summary of these guidelines and discusses some of the concepts, s atistical procedures, and techniques used to maintain a multiyear suspended sediment time series.

Voluntary Environmental Governance Arrangements

NARCIS (Netherlands)

van der Heijden, J.

2012-01-01

Voluntary environmental governance arrangements have focal attention in studies on environmental policy, regulation and governance. The four major debates in the contemporary literature on voluntary environmental governance arrangements are studied. The literature falls short of sufficiently

Minimization of Load Variance in Power Grids—Investigation on Optimal Vehicle-to-Grid Scheduling

DEFF Research Database (Denmark)

Tan, Kang Miao; Ramachandaramurthy, Vigna K.; Yong, Jia Ying

2017-01-01

-to-grid optimization algorithm is implemented and tested in MATLAB software (R2013a, MathWorks, Natick, MA, USA). The performance of the optimization algorithm depends heavily on the setting of the target load, power grid load and capability of the grid-connected electric vehicles. Hence, the performance...... of the proposed algorithm under various target load and electric vehicles’ state of charge selections were analysed. The effectiveness of the vehicle-to-grid scheduling to implement the appropriate peak load shaving and load levelling services for the grid load variance minimization is verified under various...

An Investigation to Resolve the Interaction Between Fuel Cell, Power Conditioning System and Application Loads

Energy Technology Data Exchange (ETDEWEB)

Sudip K. Mazumder

2005-12-31

Development of high-performance and durable solidoxide fuel cells (SOFCs) and a SOFC power-generating system requires knowledge of the feedback effects from the power-conditioning electronics and from application-electrical-power circuits that may pass through or excite the power-electronics subsystem (PES). Therefore, it is important to develop analytical models and methodologies, which can be used to investigate and mitigate the effects of the electrical feedbacks from the PES and the application loads (ALs) on the reliability and performance of SOFC systems for stationary and non-stationary applications. However, any such attempt to resolve the electrical impacts of the PES on the SOFC would be incomplete unless one utilizes a comprehensive analysis, which takes into account the interactions of SOFC, PES, balance-of-plant system (BOPS), and ALs as a whole. SOFCs respond quickly to changes in load and exhibit high part- and full-load efficiencies due to its rapid electrochemistry, which is not true for the thermal and mechanical time constants of the BOPS, where load-following time constants are, typically, several orders of magnitude higher. This dichotomy can affect the lifetime and durability of the SOFCSs and limit the applicability of SOFC systems for load-varying stationary and transportation applications. Furthermore, without validated analytical models and investigative design and optimization methodologies, realizations of cost-effective, reliable, and optimal PESs (and power-management controls), in particular, and SOFC systems, in general, are difficult. On the whole, the research effort can lead to (a) cost-constrained optimal PES design for high-performance SOFCS and high energy efficiency and power density, (b) effective SOFC power-system design, analyses, and optimization, and (c) controllers and modulation schemes for mitigation of electrical impacts and wider-stability margin and enhanced system efficiency.

A fast and optimized dynamic economic load dispatch for large scale power systems

International Nuclear Information System (INIS)

Musse Mohamud Ahmed; Mohd Ruddin Ab Ghani; Ismail Hassan

2000-01-01

This paper presents Lagrangian Multipliers (LM) and Linear Programming (LP) based dynamic economic load dispatch (DELD) solution for large-scale power system operations. It is to minimize the operation cost of power generation. units subject to the considered constraints. After individual generator units are economically loaded and periodically dispatched, fast and optimized DELD has been achieved. DELD with period intervals has been taken into consideration The results found from the algorithm based on LM and LP techniques appear to be modest in both optimizing the operation cost and achieving fast computation. (author)

Terricolous alpine lichens are sensitive to both load and concentration of applied nitrogen and have potential as bioindicators of nitrogen deposition

International Nuclear Information System (INIS)

Britton, Andrea J.; Fisher, Julia M.

2010-01-01

The influence of applied nitrogen (N) concentration and load on thallus chemistry and growth of five terricolous alpine lichen species was investigated in a three-month N addition study. Thallus N content was influenced by both concentration and load; but the relative importance of these parameters varied between species. Growth was most affected by concentration. Thresholds for effects observed in this study support a low critical load for terricolous lichen communities ( -1 y -1 ) and suggest that concentrations of N currently encountered in UK cloudwater may have detrimental effects on the growth of sensitive species. The significance of N concentration effects on sensitive species also highlights the need to avoid artificially high concentrations when designing N addition experiments. Given the sensitivity of some species to extremely low loads and concentrations of N we suggest that terricolous lichens have potential as indicators of deposition and impact in northern and alpine ecosystems. - Terricolous lichen species' N content responds to both applied N concentration and load while applied N concentration has greatest effects on growth.

Terricolous alpine lichens are sensitive to both load and concentration of applied nitrogen and have potential as bioindicators of nitrogen deposition

Energy Technology Data Exchange (ETDEWEB)

Britton, Andrea J., E-mail: a.britton@macaulay.ac.u [Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom); Fisher, Julia M. [Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom)

2010-05-15

The influence of applied nitrogen (N) concentration and load on thallus chemistry and growth of five terricolous alpine lichen species was investigated in a three-month N addition study. Thallus N content was influenced by both concentration and load; but the relative importance of these parameters varied between species. Growth was most affected by concentration. Thresholds for effects observed in this study support a low critical load for terricolous lichen communities (<7.5 kg N ha{sup -1} y{sup -1}) and suggest that concentrations of N currently encountered in UK cloudwater may have detrimental effects on the growth of sensitive species. The significance of N concentration effects on sensitive species also highlights the need to avoid artificially high concentrations when designing N addition experiments. Given the sensitivity of some species to extremely low loads and concentrations of N we suggest that terricolous lichens have potential as indicators of deposition and impact in northern and alpine ecosystems. - Terricolous lichen species' N content responds to both applied N concentration and load while applied N concentration has greatest effects on growth.

Simultaneous Wireless Power Transfer and Data Communication Using Synchronous Pulse-Controlled Load Modulation.

Science.gov (United States)

Mao, Shitong; Wang, Hao; Zhu, Chunbo; Mao, Zhi-Hong; Sun, Mingui

2017-10-01

Wireless Power Transfer (WPT) and wireless data communication are both important problems of research with various applications, especially in medicine. However, these two problems are usually studied separately. In this work, we present a joint study of both problems. Most medical electronic devices, such as smart implants, must have both a power supply to allow continuous operation and a communication link to pass information. Traditionally, separate wireless channels for power transfer and communication are utilized, which complicate the system structure, increase power consumption and make device miniaturization difficult. A more effective approach is to use a single wireless link with both functions of delivering power and passing information. We present a design of such a wireless link in which power and data travel in opposite directions. In order to aggressively miniaturize the implant and reduce power consumption, we eliminate the traditional multi-bit Analog-to-Digital Converter (ADC), digital memory and data transmission circuits all together. Instead, we use a pulse stream, which is obtained from the original biological signal, by a sigma-delta converter and an edge detector, to alter the load properties of the WPT channel. The resulting WPT signal is synchronized with the load changes therefore requiring no memory elements to record inter-pulse intervals. We take advantage of the high sensitivity of the resonant WPT to the load change, and the system dynamic response is used to transfer each pulse. The transient time of the WPT system is analyzed using the coupling mode theory (CMT). Our experimental results show that the memoryless approach works well for both power delivery and data transmission, providing a new wireless platform for the design of future miniaturized medical implants.

International Voluntary Renewable Energy Markets (Presentation)

Energy Technology Data Exchange (ETDEWEB)

Heeter, J.

2012-06-01

This presentation provides an overview of international voluntary renewable energy markets, with a focus on the United States and Europe. The voluntary renewable energy market is the market in which consumers and institutions purchase renewable energy to match their electricity needs on a voluntary basis. In 2010, the U.S. voluntary market was estimated at 35 terawatt-hours (TWh) compared to 300 TWh in the European market, though key differences exist. On a customer basis, Australia has historically had the largest number of customers, pricing for voluntary certificates remains low, at less than $1 megawatt-hour, though prices depend on technology.

Multi-objective Extremum Seeking Control for Enhancement of Wind Turbine Power Capture with Load Reduction

Science.gov (United States)

Xiao, Yan; Li, Yaoyu; Rotea, Mario A.

2016-09-01

The primary objective in below rated wind speed (Region 2) is to maximize the turbine's energy capture. Due to uncertainty, variability of turbine characteristics and lack of inexpensive but precise wind measurements, model-free control strategies that do not use wind measurements such as Extremum Seeking Control (ESC) have received significant attention. Based on a dither-demodulation scheme, ESC can maximize the wind power capture in real time despite uncertainty, variabilities and lack of accurate wind measurements. The existing work on ESC based wind turbine control focuses on power capture only. In this paper, a multi-objective extremum seeking control strategy is proposed to achieve nearly optimum wind energy capture while decreasing structural fatigue loads. The performance index of the ESC combines the rotor power and penalty terms of the standard deviations of selected fatigue load variables. Simulation studies of the proposed multi-objective ESC demonstrate that the damage-equivalent loads of tower and/or blade loads can be reduced with slight compromise in energy capture.

Robust Distributed Model Predictive Load Frequency Control of Interconnected Power System

Directory of Open Access Journals (Sweden)

Xiangjie Liu

2013-01-01

Full Text Available Considering the load frequency control (LFC of large-scale power system, a robust distributed model predictive control (RDMPC is presented. The system uncertainty according to power system parameter variation alone with the generation rate constraints (GRC is included in the synthesis procedure. The entire power system is composed of several control areas, and the problem is formulated as convex optimization problem with linear matrix inequalities (LMI that can be solved efficiently. It minimizes an upper bound on a robust performance objective for each subsystem. Simulation results show good dynamic response and robustness in the presence of power system dynamic uncertainties.

Possible standards for relieving the load of operational thermal power plants to the minimum of the power system's electric loads

Energy Technology Data Exchange (ETDEWEB)

Gitman, M.I.; Smirnov, I.A.

1988-03-01

Describes how operational measures involving feeding the steam extraction load into existing off-peak hot-water boilers produce a reduction in electric power at night and on public holidays by an average of 35% without the need for reconstruction, special equipment or changing the heat circuit. This method enables coal-fired central heating systems to be relieved by 20-30% and gaz-mazout systems (the majority) by 50-70%. To compensate for the loss of manoeuverability in central heating units on holidays in the colder period of the year, it may be necessary to stop supplementary power units (KEhS units) several times a year. 5 refs.

Changes in power and force generation during coupled eccentric-concentric versus concentric muscle contraction with training and aging

DEFF Research Database (Denmark)

Caserotti, Paolo; Aagaard, Per; Puggaard, Lis

2008-01-01

Age-related decline in maximal concentric muscle power is associated with frailty and functional impairments in the elderly. Compared to concentric contraction, mechanical muscle output is generally enhanced when muscles are rapidly pre-stretched (eccentric contraction), albeit less pronounced...... with increasing age. Exercise has been recommended to prevent loss of muscle power and function and recent guidelines indicate training program for increasing muscle power highly relevant for elderly subjects. This study examined the differences in muscle power, force and movement pattern during concentric......) and JH increased in training group (P age-related decline in muscle power and functional performance observed in the control subjects, while substantial gains...

Analysis on capability of load following for nuclear power plants abroad and its enlightenment

Science.gov (United States)

Zheng, Kuan; Zhang, Fu-qiang; Deng, Ting-ting; Zhang, Jin-fang; Hao, Weihua

2017-01-01

With the acceleration adjustment of China’s energy structure, the development of nuclear power plants in China has been going back to the fast track. While as the trend of slowing electric power demand is now unmistakable, it enforces the power system to face much greater pressure in some coastal zones where the nuclear power plants are of a comparative big proportion, such as Fujian province and Liaoning province. In this paper, the capability of load following of nuclear power plants of some developed countries with high proportion of nuclear power generation such as France, US and Japan are analysed, also from the aspects including the safety, the economy and their practical operation experience is studied. The feasibility of nuclear power plants to participate in the peak regulation of system is also studied and summarized. The results of this paper could be of good reference value for the China’s nuclear power plants to participate in system load following, and also of great significance for the development of the nuclear power plants in China.

New approaches to provide ride-through for critical loads in electric power distribution systems

Science.gov (United States)

Montero-Hernandez, Oscar C.

2001-07-01

The extensive use of electronic circuits has enabled modernization, automation, miniaturization, high quality, low cost, and other achievements regarding electric loads in the last decades. However, modern electronic circuits and systems are extremely sensitive to disturbances from the electric power supply. In fact, the rate at which these disturbances happen is considerable as has been documented in recent years. In response to the power quality concerns presented previously, this dissertation is proposing new approaches to provide ride-through for critical loads during voltage disturbances with emphasis on voltage sags. In this dissertation, a new approach based on an AC-DC-AC system is proposed to provide ride-through for critical loads connected in buildings and/or an industrial system. In this approach, a three-phase IGBT inverter with a built in Dc-link voltage regulator is suitably controlled along with static by-pass switches to provide continuous power to critical loads. During a disturbance, the input utility source is disconnected and the power from the inverter is connected to the load. The remaining voltage in the AC supply is converted to DC and compensated before being applied to the inverter and the load. After detecting normal utility conditions, power from the utility is restored to the critical load. In order to achieve an extended ride-through capability a second approach is introduced. In this case, the Dc-link voltage regulator is performed by a DC-DC Buck-Boost converter. This new approach has the capability to mitigate voltage variations below and above the nominal value. In the third approach presented in this dissertation, a three-phase AC to AC boost converter is investigated. This converter provides a boosting action for the utility input voltages, right before they are applied to the load. The proposed Pulse Width Modulation (PWM) control strategy ensures independent control of each phase and compensates for both single-phase or poly

Recent research in electric power pricing and load management

International Nuclear Information System (INIS)

Tabors, R.D.

1990-01-01

Reliable electricity is a necessity for industrial and economic development. In the developing nations, power systems are growing rapidly. Typically, demand for electricity grows faster than either total energy demand or gross domestic product. Load management systems and innovative tariff structures offer to utilities potentially significant operating and capital cost savings through increased efficiency. Benefits must be weighed against the costs of implementation, communication, control and monitoring. When comparing developed and developing country utilities one may conclude that the developing countries may have far more to gain from direct load management and innovative tariff systems. They may be able to introduce variable (cost dependent/time dependent) reliability as opposed to the constant reliability expected in the USA and Western Europe; and many utilities may be able to design more flexible (and less costly) utility systems around a combination of load management and pricing structures, that encourage a higher level of interaction between customer and utility than is the case in the more developed utilities. (author). 84 refs

The design, fabrication and maintenance of semi-trailers employed in the highway transport of weight-concentrated radioactive loads

Energy Technology Data Exchange (ETDEWEB)

Huffman, D.S. [Allied-Signal Inc., Metropolis, IL (United States)

1991-12-31

Transportation of weight-concentrated radioactive loads by truck is an essential part of a safe and economical nuclear industry. This proposed standard presents guidance and performance criteria for the safe transport of these weight-concentrated radioactive loads. ANSI N14.30 will detail specific requirements for the design, fabrication, testing, in-service inspections, maintenance and certification of the semi-trailers to be employed in said service. Furthermore, guidelines for a quality assurance program are also enumerated. This standard would apply to any semi-trailer that may or may not be specifically designed to carry weight-concentrated loads. Equipment not suitable per the criteria established in the standard would be removed from service. The nature of the nuclear industry and the need for a positive public perception of the various processes and players, mandates that the highway transportation of weight-concentrated radioactive loads be standardized and made inherently safe. This proposed standard takes a giant step in that direction.

Status and Trends in U.S. Compliance and Voluntary Renewable Energy Certificate Markets (2010 Data)

Energy Technology Data Exchange (ETDEWEB)

Heeter, Jenny [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bird, Lori [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2011-10-01

The "voluntary" or "green power" market is that in which consumers and institutions voluntarily purchase renewable energy to match all or part of their electricity needs. Voluntary action provides a revenue stream for renewable energy projects and raises consumer awareness of the benefits of renewable energy. There are numerous ways consumers and institutions can purchase renewable energy. Historically, the voluntary market has consisted of three market sectors: (1) utility green pricing programs (in states with regulated electricity markets), (2) competitive suppliers (in states with restructured electricity markets), and (3) unbundled renewable electricity certificate (REC) markets, where RECs are purchased by consumers separately from electricity ("unbundled").

78 FR 69793 - Voluntary Remedial Actions and Guidelines for Voluntary Recall Notices

Science.gov (United States)

2013-11-21

...'' and ``hard copy'' as possible forms of direct voluntary recall notice. Because firms often lack... formatting of a voluntary recall notice in the form of a press release should comport with the most current... transmitted using an electronic medium and in hard copy form. Acceptable forms of, and means for...

Load Frequency Control of AC Microgrid Interconnected Thermal Power System

Science.gov (United States)

Lal, Deepak Kumar; Barisal, Ajit Kumar

2017-08-01

In this paper, a microgrid (MG) power generation system is interconnected with a single area reheat thermal power system for load frequency control study. A new meta-heuristic optimization algorithm i.e. Moth-Flame Optimization (MFO) algorithm is applied to evaluate optimal gains of the fuzzy based proportional, integral and derivative (PID) controllers. The system dynamic performance is studied by comparing the results with MFO optimized classical PI/PID controllers. Also the system performance is investigated with fuzzy PID controller optimized by recently developed grey wolf optimizer (GWO) algorithm, which has proven its superiority over other previously developed algorithm in many interconnected power systems.

The voluntary offset - approaches and limitations

International Nuclear Information System (INIS)

2012-06-01

After having briefly presented the voluntary offset mechanism which aims at funding a project of reduction or capture of greenhouse gas emissions, this document describes the approach to be followed to adopt this voluntary offset, for individuals as well as for companies, communities or event organisations. It describes other important context issues (projects developed under the voluntary offset, actors of the voluntary offsetting market, market status, offset labels), and how to proceed in practice (definition of objectives and expectations, search for needed requirements, to ensure the meeting of requirements with respect to expectations). It addresses the case of voluntary offset in France (difficult implantation, possible solutions)

Green Power Partnership 100 Green Power Users

Science.gov (United States)

EPA's Green Power Partnership is a voluntary program designed to reduce the environmental impact of electricity generation by promoting renewable energy. Partners on this list use green power to meet 100 of their U.S. organization-wide electricity use.

A GPS-Based Control Method for Load Sharing and Power Quality Improvement in Microgrids

DEFF Research Database (Denmark)

Golsorkhi, Mohammad; Lu, Dylan; Savaghebi, Mehdi

2016-01-01

This paper proposes a novel control method for accurate sharing of load current among the Distributed Energy Resources (DER) and high power quality operating in islanded ac microgrids. This control scheme is based on hierarchical structure comprising of decentralized primary controllers and a cen....... The secondary controller produces compensation signals at fundamental and dominant harmonics to improve the voltage quality at a sensitive load bus. Experimental results are presented to validate the efficacy of the proposed method.......This paper proposes a novel control method for accurate sharing of load current among the Distributed Energy Resources (DER) and high power quality operating in islanded ac microgrids. This control scheme is based on hierarchical structure comprising of decentralized primary controllers...

Re-assessment of road accident data-analysis policy : applying theory from involuntary, high-consequence, low-probability events like nuclear power plant meltdowns to voluntary, low-consequence, high-probability events like traffic accidents

Science.gov (United States)

2002-02-01

This report examines the literature on involuntary, high-consequence, low-probability (IHL) events like nuclear power plant meltdowns to determine what can be applied to the problem of voluntary, low-consequence high-probability (VLH) events like tra...

Worst-case residual clipping noise power model for bit loading in LACO-OFDM

KAUST Repository

Zhang, Zhenyu; Chaaban, Anas; Shen, Chao; Elgala, Hany; Ng, Tien Khee; Ooi, Boon S.; Alouini, Mohamed-Slim

2018-01-01

Layered ACO-OFDM enjoys better spectral efficiency than ACO-OFDM, but its performance is challenged by residual clipping noise (RCN). In this paper, the power of RCN of LACO-OFDM is analyzed and modeled. As RCN is data-dependent, the worst-case situation is considered. A worst-case indicator is defined for relating the power of RCN and the power of noise at the receiver, wherein a linear relation is shown to be a practical approximation. An LACO-OFDM bit-loading experiment is performed to examine the proposed RCN power model for data rates of 6 to 7 Gbps. The experiment's results show that accounting for RCN has two advantages. First, it leads to better bit loading and achieves up to 59% lower overall bit-error rate (BER) than when the RCN is ignored. Second, it balances the BER across layers, which is a desired property from a channel coding perspective.

Modeling of unified power quality conditioner (UPQC) in distribution systems load flow

International Nuclear Information System (INIS)

Hosseini, M.; Shayanfar, H.A.; Fotuhi-Firuzabad, M.

2009-01-01

This paper presents modeling of unified power quality conditioner (UPQC) in load flow calculations for steady-state voltage compensation. An accurate model for this device is derived to use in load flow calculations. The rating of this device as well as direction of reactive power injection required to compensate voltage to the desired value (1 p.u.) is derived and discussed analytically and mathematically using phasor diagram method. Since performance of the compensator varies when it reaches to its maximum capacity, modeling of UPQC in its maximum rating of reactive power injection is derived. The validity of the proposed model is examined using two standard distribution systems consisting of 33 and 69 nodes, respectively. The best location of UPQC for under voltage problem mitigation in the distribution network is determined. The results show the validity of the proposed model for UPQC in large distribution systems.

Modeling of unified power quality conditioner (UPQC) in distribution systems load flow

Energy Technology Data Exchange (ETDEWEB)

Hosseini, M.; Shayanfar, H.A. [Center of Excellence for Power System Automation and Operation, Department of Electrical Engineering, Iran University of Science and Technology, Tehran (Iran); Fotuhi-Firuzabad, M. [Department of Electrical Engineering, Sharif University of Technology, Tehran (Iran)

2009-06-15

This paper presents modeling of unified power quality conditioner (UPQC) in load flow calculations for steady-state voltage compensation. An accurate model for this device is derived to use in load flow calculations. The rating of this device as well as direction of reactive power injection required to compensate voltage to the desired value (1 p.u.) is derived and discussed analytically and mathematically using phasor diagram method. Since performance of the compensator varies when it reaches to its maximum capacity, modeling of UPQC in its maximum rating of reactive power injection is derived. The validity of the proposed model is examined using two standard distribution systems consisting of 33 and 69 nodes, respectively. The best location of UPQC for under voltage problem mitigation in the distribution network is determined. The results show the validity of the proposed model for UPQC in large distribution systems. (author)

Heat Transfer Phenomena in Concentrating Solar Power Systems.

Energy Technology Data Exchange (ETDEWEB)

Armijo, Kenneth Miguel; Shinde, Subhash L.

2016-11-01

Concentrating solar power (CSP) utilizes solar thermal energy to drive a thermal power cycle for the generation of electricity. CSP systems are facilitated as large, centralized power plants , such as power towers and trough systems, to take advantage of ec onomies of scale through dispatchable thermal energy storage, which is a principle advantage over other energy generation systems . Additionally, the combination of large solar concentration ratios with high solar conversion efficiencies provides a strong o pportunity of employment of specific power cycles such as the Brayton gas cycle that utilizes super critical fluids such as supercritical carbon dioxide (s CO 2 ) , compared to other sola r - fossil hybrid power plants. A comprehensive thermal - fluids examination is provided by this work of various heat transfer phenomena evident in CSP technologies. These include sub - systems and heat transfer fundamental phenomena evident within CSP systems , which include s receivers, heat transfer fluids (HTFs), thermal storage me dia and system designs , thermodynamic power block systems/components, as well as high - temperature materials. This work provides literature reviews, trade studies, and phenomenological comparisons of heat transfer media (HTM) and components and systems, all for promotion of high performance and efficient CSP systems. In addition, f urther investigations are also conducted that provide advanced heat transfer modeling approaches for gas - particle receiver systems , as well as performance/efficiency enhancement re commendations, particularly for solarized supercritical power systems .

Robust nonlinear model predictive control for nuclear power plants in load following operations with bounded xenon oscillations

International Nuclear Information System (INIS)

Eliasi, H.; Menhaj, M.B.; Davilu, H.

2011-01-01

Research highlights: → In this work, a robust nonlinear model predictive control algorithm is developed. → This algorithm is applied to control the power level for load following. → The state constraints are imposed on the predicted trajectory during optimization. → The xenon oscillations are the main constraint for the load following problem. → In this algorithm, xenon oscillations are bounded within acceptable limits. - Abstract: One of the important operations in nuclear power plants is load-following in which imbalance of axial power distribution induces xenon oscillations. These oscillations must be maintained within acceptable limits otherwise the nuclear power plant could become unstable. Therefore, bounded xenon oscillation considered to be a constraint for the load-following operation. In this paper, a robust nonlinear model predictive control for the load-following operation problem is proposed that ensures xenon oscillations are kept bounded within acceptable limits. The proposed controller uses constant axial offset (AO) strategy to maintain xenon oscillations to be bounded. The constant AO is a robust state constraint for load-following problem. The controller imposes restricted state constraints on the predicted trajectory during optimization which guarantees robust satisfaction of state constraints without restoring to a min-max optimization problem. Simulation results show that the proposed controller for the load-following operation is so effective so that the xenon oscillations kept bounded in the given region.

Power variables and bilateral force differences during unloaded and loaded squat jumps in high performance alpine ski racers.

Science.gov (United States)

Patterson, Carson; Raschner, Christian; Platzer, Hans-Peter

2009-05-01

The purpose of this paper was to investigate the power-load relationship and to compare power variables and bilateral force imbalances between sexes with squat jumps. Twenty men and 17 women, all members of the Austrian alpine ski team (junior and European Cup), performed unloaded and loaded (barbell loads equal to 25, 50, 75, and 100% body weight [BW]) squat jumps with free weights using a specially designed spotting system. Ground reaction force records from 2 force platforms were used to calculate relative average power (P), relative average power in the first 100 ms of the jump (P01), relative average power in the first 200 ms of the jump (P02), jump height, percentage of best jump height (%Jump), and maximal force difference between dominant and nondominant leg (Fmaxdiff). The men displayed significantly higher values at all loads for P and jump height (p free weights.

Research on Power System Scheduling Improving Wind Power Accommodation Considering Thermal Energy Storage and Flexible Load

Science.gov (United States)

Zou, Chenlu; Cui, Xue; Wang, Heng; Zhou, Bin; Liu, Yang

2018-01-01

In the case of rapid development of wind power and heavy wind curtailment, the study of wind power accommodation of combined heat and power system has become the focus of attention. A two-stage scheduling model contains of wind power, thermal energy storage, CHP unit and flexible load were constructed. This model with the objective function of minimizing wind curtailment and the operation cost of units while taking into account of the total coal consumption of units, constraint of thermal energy storage and electricity-heat characteristic of CHP. This paper uses MICA to solve the problem of too many constraints and make the solution more feasible. A numerical example showed that the two stage decision scheduling model can consume more wind power, and it could provide a reference for combined heat and power system short-term operation

Robust feedback-linearization control for axial power distribution in pressurized water reactors during load-following operation

OpenAIRE

M. Zaidabadi nejad; G.R. Ansarifar

2018-01-01

Improved load-following capability is one of the most important technical tasks of a pressurized water reactor. Controlling the nuclear reactor core during load-following operation leads to some difficulties. These difficulties mainly arise from nuclear reactor core limitations in local power peaking: the core is subjected to sharp and large variation of local power density during transients. Axial offset (AO) is the parameter usually used to represent the core power peaking. One of the impor...

[The investigation of control mechanisms of stepping rhythm in human in the air-stepping conditions during passive and voluntary leg movements].

Science.gov (United States)

Solopova, I A; Selionon, V A; Grishin, A A

2010-01-01

In unloading condition the degree of activation of the central stepping program was investigated during passive leg movements in healthy subjects, as well as the excitability of spinal motoneurons during passive and voluntary stepping movement. Passive stepping movements with characteristics maximally approximated to those during voluntary stepping were accomplished by experimenter. The comparison of the muscle activity bursts during voluntary and imposed movements was made. In addition to that the influence of artificially created loading onto the foot to the leg movement characteristics was analyzed. Spinal motoneuron excitability was estimated by means of evaluation of amplitude modulation of the soleus H-reflex. The changes of H-reflexes under the fixation of knee or hip joints were also studied. In majority of subjects the passive movements were accompanied by bursts of EMG activity of hip muscles (and sometimes of knee muscles), which timing during step cycle was coincided with burst timing of voluntary step cycle. In many cases the bursts of EMG activity during passive movements exceeded activity in homonymous muscles during voluntary stepping. The foot loading imitation exerted essential influence on distal parts of moving extremity during voluntary as well passive movements, that was expressed in the appearance of movements in the ankle joint and accompanied by emergence and increasing of phasic EMG activity of shank muscles. The excitability of motoneurons during passive movements was greater then during voluntary ones. The changes and modulation of H-reflex throughout the step cycle without restriction of joint mobility and during exclusion of hip joint mobility were similar. The knee joint fixation exerted the greater influence. It is supposed that imposed movements activate the same mechanisms of rhythm generation as a supraspinal commands during voluntary movements. In the conditions of passive movements the presynaptic inhibition depend on afferent

Load follow operation in nuclear power plants and its influence on PWR fuel behaviour

International Nuclear Information System (INIS)

Nagino, Y.; Miyazaki, Y.

1980-01-01

The contribution of nuclear power generation to our company's grid system is becoming greater each year, which makes it necessary to operate nuclear power plants with load follow mode in the near future. (author)

Swarm Intelligence-Based Hybrid Models for Short-Term Power Load Prediction

Directory of Open Access Journals (Sweden)

Jianzhou Wang

2014-01-01

Full Text Available Swarm intelligence (SI is widely and successfully applied in the engineering field to solve practical optimization problems because various hybrid models, which are based on the SI algorithm and statistical models, are developed to further improve the predictive abilities. In this paper, hybrid intelligent forecasting models based on the cuckoo search (CS as well as the singular spectrum analysis (SSA, time series, and machine learning methods are proposed to conduct short-term power load prediction. The forecasting performance of the proposed models is augmented by a rolling multistep strategy over the prediction horizon. The test results are representative of the out-performance of the SSA and CS in tuning the seasonal autoregressive integrated moving average (SARIMA and support vector regression (SVR in improving load forecasting, which indicates that both the SSA-based data denoising and SI-based intelligent optimization strategy can effectively improve the model’s predictive performance. Additionally, the proposed CS-SSA-SARIMA and CS-SSA-SVR models provide very impressive forecasting results, demonstrating their strong robustness and universal forecasting capacities in terms of short-term power load prediction 24 hours in advance.

AN INVESTIGATION TO RESOLVE THE INTERACTION BETWEEN FUEL CELL, POWER CONDITIONING SYSTEM AND APPLICATION LOADS

Energy Technology Data Exchange (ETDEWEB)

Sudip K. Mazumder; Chuck McKintyre; Dan Herbison; Doug Nelson; Comas Haynes; Michael von Spakovsky; Joseph Hartvigsen; S. Elangovan

2003-11-03

Solid-Oxide Fuel Cell (SOFC) stacks respond quickly to changes in load and exhibit high part- and full-load efficiencies due to its rapid electrochemistry. However, this is not true for the thermal, mechanical, and chemical balance-of-plant subsystem (BOPS), where load-following time constants are, typically, several orders of magnitude higher. This dichotomy diminishes the reliability and performance of the electrode with increasing demand of load. Because these unwanted phenomena are not well understood, the manufacturers of SOFC use conservative schemes (such as, delayed load-following to compensate for slow BOPS response or expensive inductor filtering) to control stack responses to load variations. This limits the applicability of SOFC systems for load-varying stationary and transportation applications from a cost standpoint. Thus, a need exists for the synthesis of component- and system-level models of SOFC power-conditioning systems and the development of methodologies for investigating the system-interaction issues (which reduce the lifetime and efficiency of a SOFC) and optimizing the responses of each subsystem, leading to optimal designs of power-conditioning electronics and optimal control strategies, which mitigate the electrical-feedback effects. Equally important are ''multiresolution'' finite-element modeling and simulation studies, which can predict the impact of changes in system-level variables (e.g., current ripple and load-transients) on the local current densities, voltages, and temperature (these parameters are very difficult or cumbersome, if not impossible to obtain) within a SOFC cell. Towards that end, for phase I of this project, sponsored by the U.S. DOE (NETL), we investigate the interactions among fuel cell, power-conditioning system, and application loads and their effects on SOFC reliability (durability) and performance. A number of methodologies have been used in Phase I to develop the steady-state and transient

Operation and thermal loading of three-level Neutral-Point-Clamped wind power converter under various grid faults

DEFF Research Database (Denmark)

Ma, Ke; Blaabjerg, Frede; Liserre, Marco

2012-01-01

In order to fulfill the continuous growing grid-side demands, the full-scale power converters are becoming more and more popular in the wind power application. Nevertheless, the more severe loading of the power semiconductor devices in the full-scale power converters, especially during Low Voltage...... Ride Through (LVRT) operation under grid faults, may compromise the reliability of the system and consequently further increase its cost. In this paper, the impact of various grid faults on a three-level Neutral-Point-Clamped (3L-NPC) grid-converter in terms of thermal loading of power semiconductor...

Rye cover crop and gamagrass strip effects on NO3 concentration and load in tile drainage.

Science.gov (United States)

Kaspar, T C; Jaynes, D B; Parkin, T B; Moorman, T B

2007-01-01

A significant portion of the NO3 from agricultural fields that contaminates surface waters in the Midwest Corn Belt is transported to streams or rivers by subsurface drainage systems or "tiles." Previous research has shown that N fertilizer management alone is not sufficient for reducing NO3 concentrations in subsurface drainage to acceptable levels; therefore, additional approaches need to be devised. We compared two cropping system modifications for NO3 concentration and load in subsurface drainage water for a no-till corn (Zea mays L.)-soybean (Glycine max [L.] Merr.) management system. In one treatment, eastern gamagrass (Tripsacum dactyloides L.) was grown in permanent 3.05-m-wide strips above the tiles. For the second treatment, a rye (Secale cereale L.) winter cover crop was seeded over the entire plot area each year near harvest and chemically killed before planting the following spring. Twelve 30.5x42.7-m subsurface-drained field plots were established in 1999 with an automated system for measuring tile flow and collecting flow-weighted samples. Both treatments and a control were initiated in 2000 and replicated four times. Full establishment of both treatments did not occur until fall 2001 because of dry conditions. Treatment comparisons were conducted from 2002 through 2005. The rye cover crop treatment significantly reduced subsurface drainage water flow-weighted NO3 concentrations and NO3 loads in all 4 yr. The rye cover crop treatment did not significantly reduce cumulative annual drainage. Averaged over 4 yr, the rye cover crop reduced flow-weighted NO3 concentrations by 59% and loads by 61%. The gamagrass strips did not significantly reduce cumulative drainage, the average annual flow-weighted NO3 concentrations, or cumulative NO3 loads averaged over the 4 yr. Rye winter cover crops grown after corn and soybean have the potential to reduce the NO3 concentrations and loads delivered to surface waters by subsurface drainage systems.

Photovoltaic power converter system with a controller configured to actively compensate load harmonics

Science.gov (United States)

de Rooij, Michael Andrew; Steigerwald, Robert Louis; Delgado, Eladio Clemente

2008-12-16

Photovoltaic power converter system including a controller configured to reduce load harmonics is provided. The system comprises a photovoltaic array and an inverter electrically coupled to the array to generate an output current for energizing a load connected to the inverter and to a mains grid supply voltage. The system further comprises a controller including a first circuit coupled to receive a load current to measure a harmonic current in the load current. The controller includes a second circuit to generate a fundamental reference drawn by the load. The controller further includes a third circuit for combining the measured harmonic current and the fundamental reference to generate a command output signal for generating the output current for energizing the load connected to the inverter. The photovoltaic system may be configured to compensate harmonic currents that may be drawn by the load.

Load flow analysis for determining the location of NPP power distribution in West Kalimantan

International Nuclear Information System (INIS)

Citra Candranurani; Rizki Finnansyah Setya Budi; Sahala M Lumbanraja

2015-01-01

Electricity crisis condition happened in West Kalimantan (Kalbar) as a result of power plant capacity almost equal to the peak load. The system will experience a shortfall if there are plants that not operating and do not have reserve. The policy of electricity planning until 2022 is replacing diesel power plant with steam power plant. For long-term planning is required the role of new and renewable energy in order to reduce dependency on fossil fuel consumption, such as NPP utilization. The purpose of this study was to determine the optimum location of the NPP power distribution in order to prepare electricity infrastructure. Load flow calculation in this study using ETAP 12.5 software. NPP is planned to supply base load, so the optimum capacity factor is above 80 %. The result show that there are three location where NPP can generate over 80 % of its capacity, namely: Mempawah Substation, Singkawang Substation, and Sambas Substation. The most optimum located in Mempawah Substation with capacity factor 83.5 %. The location of the three Substation are onshore and in line with one requirement for NPP construction, namely: the availability of cooling water. (author)

Insurance risk of nuclear power plant concentrations

International Nuclear Information System (INIS)

Feldmann, J.

1976-01-01

The limited number of sites available in the Federal Republic of Germany for the erection of nuclear power plants has resulted in the construction of multiple nuclear generating units on a few sites, such as Biblis, Gundremmingen and Neckarwestheim. At a value invested of approximately DM 1,200/kW this corresponds to a property concentration on one site worth DM 2 - 3 billion and more. This raises the question whether a concentration of value of this magnitude does not already exceed the limits of bearable economic risks. The property risk of a nuclear power plant, as that of any other industrial plant, is a function of the property that can be destroyed in a maximum probable loss. Insurance companies subdivide plants into so-called complex areas in which fire damage or nuclear damage could spread. While in some foreign countries twin nuclear power plants are built, where the technical systems of both units are installed in one building without any physical separation, dual unit plants are built in the Federal Republic in which the complexes with a high concentration of valuable property are physically separate building units. As a result of this separation, property insurance companies have no grounds for assessing the risk and hence, the premium different from those of single unit plants. (orig.) [de

Remote control and load management of electric power distribution networks; Fjaerroevervakning och belastningsstyrning av eldistributionsnaet

Energy Technology Data Exchange (ETDEWEB)

Jonsson, Mats; Larsson, Mikael

1993-02-01

Remote control and load management increase the electricity distributors possibilities to even out the consumption of electricity for optimal usage of electricity subscription and supply system. Controlling can be done either through technology or through encouragement of off-peak consumption. There are a number of similar systems for controlling consumption, where the manufacturers have chosen different ways to solve the main problem, namely the communication. We have concentrated in examining systems which communicate through the supply system, different types of telephone connections and wireless communication links. In the future demands for better electricity consumption control will be put forward. This will bring along a greater need at distribution level for continuous monitoring of purchased and used electricity flow. The distributors will also need better possibilities to directly affect power consumption. Those manufacturers who do not use load management today should acquire experience through provincial installations in suitable areas with equipment ready for tomorrows needs and requirements. Today there are some different systems on the market that offer flexibility and ready-to-use possibilities. (3 refs., 17 figs.)

Investigation of load leveling in Hokuriku Electric Power Co., Inc.; Hokuriku denryoku no fuka heijunka eno torikumi

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-08-01

Hokuriku Electric Power Co., Inc. aims at an around 2% improvement of the load factor up to 2005, by which the quick and proper service and the proposal of load leveling menu are planned. This paper describes an outline of the investigation of load leveling. Various programs have been proposed so that the customers can further shift the load by their consideration. Proposed systems include the time-of-day electricity rate system, the load regulation contract system for industries, the seasonal time-of-day rate system, the electric power system for snowmelt in which the load is dumped at the peak, and the secondary electric power system for snowmelt. Accompanying with the revision of electric utility law, the enlargement of its available time, the price reduction, and the discount rate system for the ice regenerative air conditioners have been provided. For the business activities, a demonstration model house was exhibited to indicate a proper house with local characteristics in Hokuriku district. Furthermore, the spreading activities of regenerative systems and the consulting activities have been positively promoted. 4 figs., 1 tab.

Determination of the wind power systems load to achieve operation in the maximum energy area

Science.gov (United States)

Chioncel, C. P.; Tirian, G. O.; Spunei, E.; Gillich, N.

2018-01-01

This paper analyses the operation of the wind turbine, WT, in the maximum power point, MPP, by linking the load of the Permanent Magnet Synchronous Generator, PMSG, with the wind speed value. The load control methods at wind power systems aiming an optimum performance in terms of energy are based on the fact that the energy captured by the wind turbine significantly depends on the mechanical angular speed of the wind turbine. The presented control method consists in determining the optimal mechanical angular speed, ωOPTIM, using an auxiliary low power wind turbine, WTAUX, operating without load, at maximum angular velocity, ωMAX. The method relies on the fact that the ratio ωOPTIM/ωMAX has a constant value for a given wind turbine and does not depend on the time variation of the wind speed values.

Worst-case residual clipping noise power model for bit loading in LACO-OFDM

KAUST Repository

Zhang, Zhenyu

2018-03-19

Layered ACO-OFDM enjoys better spectral efficiency than ACO-OFDM, but its performance is challenged by residual clipping noise (RCN). In this paper, the power of RCN of LACO-OFDM is analyzed and modeled. As RCN is data-dependent, the worst-case situation is considered. A worst-case indicator is defined for relating the power of RCN and the power of noise at the receiver, wherein a linear relation is shown to be a practical approximation. An LACO-OFDM bit-loading experiment is performed to examine the proposed RCN power model for data rates of 6 to 7 Gbps. The experiment\\'s results show that accounting for RCN has two advantages. First, it leads to better bit loading and achieves up to 59% lower overall bit-error rate (BER) than when the RCN is ignored. Second, it balances the BER across layers, which is a desired property from a channel coding perspective.

Concentrating Solar Power Systems

Science.gov (United States)

Pitz-Paal, R.

2017-07-01

Development of Concentrating Solar Power Systems has started about 40 years ago. A first commercial implementation was performed between 1985 and 1991 in California. However, a drop in gas prices caused a longer period without further deployment. It was overcome in 2007 when new incentive schemes for renewables in Spain and the US enabled a commercial restart. In 2016, almost 100 commercial CSP plants with more than 5GW are installed worldwide. This paper describes the physical background of CSP technology, its technical characteristics and concepts. Furthermore, it discusses system performances, cost structures and the expected advancement.

Test and evaluation of load converter topologies used in the Space Station Freedom power management and distribution dc test bed

Science.gov (United States)

Lebron, Ramon C.; Oliver, Angela C.; Bodi, Robert F.

1991-01-01

Power components hardware in support of the Space Station freedom dc Electric Power System were tested. One type of breadboard hardware tested is the dc Load Converter Unit, which constitutes the power interface between the electric power system and the actual load. These units are dc to dc converters that provide the final system regulation before power is delivered to the load. Three load converters were tested: a series resonant converter, a series inductor switch-mode converter, and a switching full-bridge forward converter. The topology, operation principles, and test results are described, in general. A comparative analysis of the three units is given with respect to efficiency, regulation, short circuit behavior (protection), and transient characteristics.

Advancing Concentrating Solar Power Research (Fact Sheet)

Energy Technology Data Exchange (ETDEWEB)

None, None

2014-02-01

Researchers at the National Renewable Energy Laboratory (NREL) provide scientific, engineering, and analytical expertise to help advance innovation in concentrating solar power (CSP). This fact sheet summarizes how NREL is advancing CSP research.

Economic emission dispatching with variations of wind power and loads using multi-objective optimization by learning automata

International Nuclear Information System (INIS)

Liao, H.L.; Wu, Q.H.; Li, Y.Z.; Jiang, L.

2014-01-01

Highlights: • Apply multi-objective optimization by learning automata to power system. • Sequentially dimensional search and state memory are incorporated. • Track dispatch under significant variations of wind power and load demand. • Good performance in terms of accuracy, distribution and computation time. - Abstract: This paper is concerned with using multi-objective optimization by learning automata (MOLA) for economic emission dispatching in the environment where wind power and loads vary. With its capabilities of sequentially dimensional search and state memory, MOLA is able to find accurate solutions while satisfying two objectives: fuel cost coupled with environmental emission and voltage stability. Its searching quality and efficiency are measured using the hypervolume indicator for investigating the quality of Pareto front, and demonstrated by tracking the dispatch solutions under significant variations of wind power and load demand. The simulation studies are carried out on the modified midwestern American electric power system and the IEEE 118-bus test system, in which wind power penetration and load variations present. Evaluated on these two power systems, MOLA is fully compared with multi-objective evolutionary algorithm based on decomposition (MOEA/D) and non-dominated sorting genetic algorithm II (NSGA-II). The simulation results have shown the superiority of MOLA over NAGA-II and MOEA/D, as it is able to obtain more accurate and widely distributed Pareto fronts. In the dynamic environment where the operation condition of both wind speed and load demand varies, MOLA outperforms the other two algorithms, with respect to the tracking ability and accuracy of the solutions

Maximum power output and load matching of a phosphoric acid fuel cell-thermoelectric generator hybrid system

Science.gov (United States)

Chen, Xiaohang; Wang, Yuan; Cai, Ling; Zhou, Yinghui

2015-10-01

Based on the current models of phosphoric acid fuel cells (PAFCs) and thermoelectric generators (TGs), a new hybrid system is proposed, in which the effects of multi-irreversibilities resulting from the activation, concentration, and ohmic overpotentials in the PAFC, Joule heat and heat leak in the TG, finite-rate heat transfer between the TG and the heat reservoirs, and heat leak from the PAFC to the environment are taken into account. Expressions for the power output and efficiency of the PAFC, TG, and hybrid system are analytically derived and directly used to discuss the performance characteristics of the hybrid system. The optimal relationship between the electric currents in the PAFC and TG is obtained. The maximum power output is numerically calculated. It is found that the maximum power output density of the hybrid system will increase about 150 Wm-2, compared with that of a single PAFC. The problem how to optimally match the load resistances of two subsystems is discussed. Some significant results for practical hybrid systems are obtained.

Perspective loads of transformer substations at development of urban power supply systems

Directory of Open Access Journals (Sweden)

Svetlana Guseva

2012-06-01

Full Text Available In work the system approach to formation of the urban power supply system is given. The hierarchical structure of the construction, voltage levels and load densities is considered. The mathematical and geometrical modeling of service areas for transformer substations of diff erent voltage is fulfi lled. Determination of perspective loads of transformer substations is given. The method of graphic placement of transformer substations in the city territory for new substations at existing structure of networks is off ered. The calculation program Microsoft EXCEL and the graphic program AutoCad are used for realization of method. The method allows fi nding a rational decision for the development of urban power supply system on the beginning design stages in conditions of the information uncertainty.

Current summary of international extreme load design requirements for nuclear power plant facilities

International Nuclear Information System (INIS)

Stevenson, J.D.

1980-01-01

The development of extreme load design criteria both as to rate and depth within any national jurisdiction as applied to nuclear power plant design is a function of several factors. The prime factor is the number of nuclear power plant facilities which are operating, under construction or planned in a given country. The second most important factor seems to be the degree of development of a domestic independent nuclear steam system supplier, NSSS vendor. Finally, countries whose domestic NSSS firms are active in the export market appear to have more active criteria development programs or at least they appear more visible to the foreign observer. For the purposes of this paper, extreme loads are defined as those loads having probability of occurence less than 10 -1 /yr and whose occurence could result in radiological consequences in excess of those permitted by national health standards. The specific loads considered include earthquake, extreme wind (tornado), airplane crash, detonation, and high energy system rupture. The paper identifies five national centers for extreme load criteria development; Canada, Great Britian, USA, USSR, and West Germany with both France and Japan also about to appear as independent centers of criteria development. Criteria under development by each national center are discussed in detail. (orig.)

Advanced operational strategy for the IRIS reactor: Load follow through mechanical shim (MSHIM)

International Nuclear Information System (INIS)

Franceschini, Fausto; Petrovic, Bojan

2008-01-01

The renaissance of nuclear power brings more attention to advanced reactor designs and their improved performance and flexibility, including their enhanced load follow capability. Reactor control strategy used to perform transients including power changes has impact on the overall control system design. In particular, as the power change is performed within a load follow maneuver, several modifications occur in the core from a neutronic view point: the fuel and moderator temperature change, the xenon concentration and distribution are modified, the power distribution skewed axially, etc. These changes need to be adequately counterbalanced to keep both the core critical and the power distribution acceptable. The traditional approach in PWRs is to compensate for the reactivity change due to the power variation by adjusting the soluble boron concentration and moving a limited number of control rod banks. However, advanced reactors may adopt a different strategy for a variety of reasons. For example, water-cooled reactors that do not use soluble boron in coolant obviously cannot use its adjustment for this purpose. Moreover, Integral Primary System Reactors (IPSRs) using soluble boron, due to their integral design, have a large inventory of primary coolant. Therefore dilution/boration strategy, while in principle an option, becomes expensive for short time changes and leads to large volume of liquid effluent, in particular toward the end of cycle. Therefore, a capability to perform load follow without changing soluble boron concentration is very desirable for a range of reactor designs. International Reactor Innovative and Secure (IRIS) is an advanced medium-size IPSR that has been selected as the reference reactor for the purpose of this study. A capability to perform load follow maneuvers without changing soluble boron concentration has been examined and demonstrated through implementation of the Westinghouse Mechanical Shim (MSHIM) control strategy. A control bank

Trends in suspended-sediment loads and concentrations in the Mississippi River Basin, 1950–2009

Science.gov (United States)

Heimann, David C.; Sprague, Lori A.; Blevins, Dale W.

2011-01-01

Trends in loads and concentrations of suspended sediment and suspended sand generally were downward for stations within the Mississippi River Basin during the 60-, 34-, and 12-year periods analyzed. Sediment transport in the lower Mississippi River has historically been, and continues to be, most closely correlative to sediment contributions from the Missouri River, which generally carried the largest annual suspended-sediment load of the major Mississippi River subbasins. The closure of Fort Randall Dam in the upper Missouri River in 1952 was the single largest event in the recorded historical decline of suspended-sediment loads in the Mississippi River Basin. Impoundments on tributaries and sediment reductions as a result of implementation of agricultural conservation practices throughout the basin likely account for much of the remaining Mississippi River sediment transport decline. Scour of the main-stem channel downstream from the upper Missouri River impoundments is likely the largest source of suspended sand in the lower Missouri River. The Ohio River was second to the Missouri River in terms of sediment contributions, followed by the upper Mississippi and Arkansas Rivers. Declines in sediment loads and concentrations continued through the most recent analysis period (1998–2009) at available Mississippi River Basin stations. Analyses of flow-adjusted concentrations of suspended sediment indicate the recent downward temporal changes generally can be explained by corresponding decreases in streamflows.

Study of regeneration system of 300 MW power unit based on nondeaerating heat balance diagram at reduced load

Science.gov (United States)

Esin, S. B.; Trifonov, N. N.; Sukhorukov, Yu. G.; Yurchenko, A. Yu.; Grigor'eva, E. B.; Snegin, I. P.; Zhivykh, D. A.; Medvedkin, A. V.; Ryabich, V. A.

2015-09-01

More than 30 power units of thermal power stations, based on the nondeaerating heat balance diagram, successfully operate in the former Soviet Union. Most of them are power units with a power of 300 MW, equipped with HTGZ and LMZ turbines. They operate according to a variable electric load curve characterized by deep reductions when undergoing night minimums. Additional extension of the range of power unit adjustment makes it possible to maintain the dispatch load curve and obtain profit for the electric power plant. The objective of this research is to carry out estimated and experimental processing of the operating regimes of the regeneration system of steam-turbine plants within the extended adjustment range and under the conditions when the constraints on the regeneration system and its equipment are removed. Constraints concerning the heat balance diagram that reduce the power unit efficiency when extending the adjustment range have been considered. Test results are presented for the nondeaerating heat balance diagram with the HTGZ turbine. Turbine pump and feed electric pump operation was studied at a power unit load of 120-300 MW. The reliability of feed pump operation is confirmed by a stable vibratory condition and the absence of cavitation noise and vibration at a frequency that characterizes the cavitation condition, as well as by oil temperature maintenance after bearings within normal limits. Cavitation performance of pumps in the studied range of their operation has been determined. Technical solutions are proposed on providing a profitable and stable operation of regeneration systems when extending the range of adjustment of power unit load. A nondeaerating diagram of high-pressure preheater (HPP) condensate discharge to the mixer. A regeneration system has been developed and studied on the operating power unit fitted with a deaeratorless thermal circuit of the system for removing the high-pressure preheater heating steam condensate to the mixer

Fatigue analysis of CANFLEX-NU fuel elements subjected to power-cyclic loads

International Nuclear Information System (INIS)

Sim, Ki Seob; Suk, Ho Chun.

1997-08-01

This report describes the fatigue analysis of the CANDU advanced fuel, so-called CANFLEX-NU, subjected to power-cyclic loads more than 1,000. The CANFLEX-NU bundle is composed of 43 elements with natural uranium fuel. As a result, the CANFLEX-NU fuel elements will maintain good integrity under the condition of 1,500 power-cycles. (author). 4 refs., 19 figs

Computerized optimum distribution of loads among the turbogenerators of fossil-fuel electric power plants

Energy Technology Data Exchange (ETDEWEB)

Foshko, L S; Zusmanovich, L B; Flos, S L; Pal' chik, V A; Konevskii, B I

1979-04-01

The problem of determining the optimum distribution of loads among turbogenerators in a fossil-fuel power plant is considered based on satisfying the following requirements: distribution of electrical and thermal loads to minimize the heat expended on the turbine unit; calculation based on turbogenerator characteristics that most completely describe operating conditions; no constraints on the configuration of turbogenerator performance characteristics; calculation of load distribution based on net characteristics including the internal needs of the turbogenerators; consideration of all operational limitations in turbogenerator working conditions; results should be applicable to any predetermined differential of the load change. A flowchart is given showing the organization of the Optim-76 program complex for solution of this problem. An example is given showing application of the Optim-76 program implemented by a Minsk-32 computer in the case of a heat and electric power station with three turbogenerators. The results show that a dynamic programming method has considerable advantages for this applicaton on third-generation computers.

Comparing Voluntary and Mandatory Gameplay

Directory of Open Access Journals (Sweden)

Esther Kuindersma

2016-09-01

Full Text Available Gameplay is commonly considered to be a voluntary activity. Game designers generally believe that voluntary gameplay is essentially different from mandatory gameplay. Such a belief may be a challenge for serious games, as instruction is usually mandatory. The article describes the outcomes of two experiments on the impact of voluntariness on the learning effect and enjoyment of a serious game. In the first experiment freedom of choosing to play a serious game was studied, with participants who had volunteered to participate. The results suggested that, contrary to the opinion of many game designers, being required to play a serious game does not automatically take the fun out of the game. The second experiment had voluntary participants and mandatory participants, who had to participate as part of a homework assignment. The outcomes show that mandatory participants enjoyed the game as much as the voluntary participants, even if they had to play the game for a minimum required time. These studies indicate that mandatory gameplay does not reduce enjoyment and learning effect.

Effects of social participation and the emergence of voluntary social interactions on household power-saving practices in post-disaster Kanagawa, Japan

International Nuclear Information System (INIS)

Nakamura, Hidenori

2013-01-01

An online social survey was conducted to reveal household electricity-saving behaviour and its relationship with participation in social group activities, as well as face-to-face and online social interactions, i.e., information sources used and information dissemination through personal networks, in a disaster-affected region of Kanagawa, Japan, during the summer of 2011. The study confirms the positive contribution of respondents’ participation in social group activities to the number of power-saving practices conducted. It also reveals the emergence of voluntary social face-to-face and/or online interactions for power-saving. The study suggests it would be useful to provide effective information to proactive individuals who are closely engaged in power-saving in households and who are proactively disseminating power-saving information practices to others. Such individuals include (1) women who have school-children and who are proactively engaging in the social interactions of their children’s schools, other parents, neighbours, as well as their own parents and relatives; and (2) men and women who are using various kinds of online interaction tools and are also engaged in face-to-face social interactions

40 CFR 86.129-00 - Road load power, test weight, and inertia weight class determination.

Science.gov (United States)

2010-07-01

... adjusted loaded vehicle weight, as defined in § 86.094-2 or 86.1803-01 as applicable. For all other vehicles, test weight basis shall be loaded vehicle weight, as defined in § 86.082-2 or 86.1803-01 as... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Road load power, test weight, and...

Power System Stability Using Decentralized Under Frequency and Voltage Load Shedding

DEFF Research Database (Denmark)

Hoseinzadeh, Bakhtyar; Silva, Filipe Faria Da; Bak, Claus Leth

2014-01-01

information to shed the loads with higher voltage decay first. Therefore, this approach deals with coordination of voltage and frequency information instead of independent methods. Numerical simulations which are carried out in DigSilent PowerFactory software confirm the efficiency of proposed methodology...

The effect of different accentuated eccentric load levels in eccentric-concentric loading contractions on acute neuromuscular, growth hormone and blood lactate responses during a hypertrophic protocol

OpenAIRE

Ojasto, Timo

2007-01-01

When accentuated load is applied during the eccentric (ECC) phase of eccentric-concentric (ECC-CON) contractions, it is defined as dynamic accentuated external resistance (DAER) exercise. This study monitored acute neuromuscular responses, growth hormone (GH) and blood lactate (La) concentrations to find out the most efficient ECC-CON loading strategy for muscle hypertrophy by employing various DAER resistances in the bench-press. Male subjects (age=32.4±4.3years, n=11) were assigned as subje...

Status and Trends in U.S. Compliance and Voluntary Renewable Energy Certificate Markets (2010 Data)

Energy Technology Data Exchange (ETDEWEB)

Heeter, J.; Bird, L.

2011-10-01

This report documents the status and trends of 'compliance'--renewable energy certificate (REC) markets used to meet state renewable portfolio standard (RPS) requirements--and 'voluntary' markets--those in which consumers and institutions purchase renewable energy to match their electricity needs on a voluntary basis. Today, 29 states and the District of Columbia have an RPS, more than half of all U.S. electricity customers have an option to purchase some type of green power product directly from a retail electricity provider, and all consumers have the option to purchase RECs. This report documents REC activities and trends in the United States. The compliance REC market analysis includes analysis of REC trading, regional REC markets, REC tracking systems, types of compliance RECs, compliance REC pricing trends, and an overview of compliance with RPS polices. The voluntary REC analysis presents data and analysis on voluntary market sales and customer participation, products and premiums, green pricing marketing and administrative expenses, voluntary REC pricing, and the voluntary carbon offsets market. The report concludes with a discussion of upcoming guidance from the Federal Trade Commission on green marketing claims, the emergence of community solar programs, and the potential impact of Dodd-Frank regulations on the REC market.

Unilateral and collusive market power in the electricity pool of England and Wales

International Nuclear Information System (INIS)

Bunn, D.W.; Martoccia, M.

2005-01-01

This paper uses a detailed market microsimulation of agent bidding behaviour to provide insights into the evolution of generator market power in the electricity pool of England and Wales. We identify an evolution, as market concentration declined, from unilateral market power dominance in the early years (1990-1996) to tacit collusive coordination towards the end (1996-2001), whereupon the pool was replaced by voluntary bilateral trading. The microsimulation analysis does not provide closed form solutions for market equilibrium nor a multi-agent co-evolutionary set of scenarios, but provides a diagnostic aid in determining when market concentration may decline to the point at which price leadership gives way to tacit collusion as means of exercising market power. (author)

Implementation and Assessment of a Decentralized Load Frequency Control: Application to Power Systems with High Wind Energy Penetration

Directory of Open Access Journals (Sweden)

Irene Muñoz-Benavente

2017-01-01

Full Text Available This paper describes and assesses a decentralized solution based on a wireless sensor-actuator network to provide primary frequency control from demand response in power systems with high wind energy penetration and, subsequently, with relevant frequency excursions. The proposed system is able to modify the electrical power demand of a variety of thermostatically-controlled loads, maintaining minimum comfort levels and minimizing both infrastructure requirements and primary reserves from the supply side. This low-cost hardware solution avoids any additional wiring, extending the wireless sensor-actuator network technology towards small customers, which account for over a 30% share of the current power demand. Frequency excursions are collected by each individual load controller, considering not only the magnitude of the frequency deviation, but also their evolution over time. Based on these time-frequency excursion characteristics, controllers are capable of modifying the power consumption of thermostatically-controlled loads by switching them off and on, thus contributing to primary frequency control in power systems with higher generation unit oscillations as a consequence of relevant wind power integration. Field tests have been carried out in a laboratory environment to assess the load controller performance, as well as to evaluate the electrical and thermal response of individual loads under frequency deviations. These frequency deviations are estimated from power systems with a high penetration of wind energy, which are more sensitive to frequency oscillations and where demand response can significantly contribute to mitigate these frequency excursions. The results, also included in the paper, evaluate the suitability of the proposed load controllers and their suitability to decrease frequency excursions from the demand side in a decentralized manner.

Comparison of the Force-, Velocity- and Power-Time Curves Between the Concentric-Only and Eccentric-Concentric Bench Press Exercises.

Science.gov (United States)

Pérez-Castilla, Alejandro; Comfort, Paul; McMahon, John J; Pestaña-Melero, Francisco Luis; García-Ramos, Amador

2018-01-17

The aim of this study was to compare the temporal and mechanical variables between the concentric-only and eccentric-concentric bench press (BP) variants. Twenty-one men (age: 22.0±4.2 years, body mass: 73.4±7.7 kg, height: 177.2±8.0 cm; one-repetition maximum [1RM]: 1.12±0.12 kg⋅kg) were evaluated during the concentric-only and eccentric-concentric BP variants using 80% 1RM. Temporal (concentric phase duration, propulsive phase duration, and time to reach the maximum values of force, velocity, and power) and mechanical variables (force, velocity, and power), determined using a linear velocity transducer, were compared between both BP variants. All temporal variables were significantly lower during the eccentric-concentric BP compared to the concentric-only BP (P velocity and power were significantly higher for the eccentric-concentric BP compared to the concentric-only BP (all P velocity (ES: 0.40) and power (ES: 0.41). The stretch-shortening cycle (i.e., eccentric-concentric BP) mainly enhanced force production at the early portion of the concentric phase, but this potentiation effect gradually reduced over the latter part of the movement. Finally, force was higher for the concentric-only BP during 49% of the concentric phase duration. These results suggest that both BP variants should be included during resistance training programs in order to optimize force output at different points of the concentric phase.

Upper limits to americium concentration in large sized sodium-cooled fast reactors loaded with metallic fuel

International Nuclear Information System (INIS)

Zhang, Youpeng; Wallenius, Janne

2014-01-01

Highlights: • The americium transmutation capability of Integral Fast Reactor was investigated. • The impact from americium introduction was parameterized by applying SERPENT Monte Carlo calculations. • Higher americium content in metallic fuel leads to a power penalty, preserving consistent safety margins. - Abstract: Transient analysis of a large sized sodium-cooled reactor loaded with metallic fuel modified by different fractions of americium have been performed. Unprotected loss-of-offsite power, unprotected loss-of-flow and unprotected transient-over-power accidents were simulated with the SAS4A/SASSYS code based on the geometrical model of an IFR with power rating of 2500 MW th , using safety parameters obtained with the SERPENT Monte Carlo code. The Ti-modified austenitic D9 steel, having higher creep rupture strength, was considered as the cladding and structural material apart from the ferritic/martensitic HT9 steel. For the reference case of U–12Pu–1Am–10Zr fuel at EOEC, the margin to fuel melt during a design basis condition UTOP is about 50 K for a maximum linear rating of 30 kW/m. In order to maintain a margin of 50 K to fuel failure, the linear power rating has to be reduced by ∼3% and 6% for 2 wt.% and 3 wt.% Am introduction into the fuel respectively. Hence, an Am concentration of 2–3 wt.% in the fuel would lead to a power penalty of 3–6%, permitting a consumption rate of 3.0–5.1 kg Am/TW h th . This consumption rate is significantly higher than the one previously obtained for oxide fuelled SFRs

Tritium concentration in ambient air around Kaiga Nuclear Power Plant

Directory of Open Access Journals (Sweden)

Srinivas S Kamath

2018-01-01

Full Text Available Tritium (3H is one of the important long-lived radioisotopes in the gaseous effluent from nuclear power plants. In this article, we present the results of 3H monitoring in ambient air samples around the Kaiga Nuclear Power Plant, on the West Coast of India. Air samples were collected by moisture condensation method and the 3H concentration was determined by liquid scintillation spectrometry. The 3H concentration in the 2.3–15 km zone of the power plant varied in the range of <0.04–6.64 Bq m−3 with a median of 0.67 Bq m−3. The samples collected from the 2.3–5 km zone of the power plant exhibit marginally higher concentration when compared to the 5–10 km and 10–15 km zones, which is as expected. The values observed in the present study for Kaiga region are similar to those reported from other nuclear power plants, both within India and other parts of the world.

Simulation of control performance under house load transients for nuclear power plant

International Nuclear Information System (INIS)

Liao Zhongyue; Wang Yuanlong; Tang Yuyuan; Liu Jiong

1999-01-01

The CATIA2 code is used to simulate the extreme normal transients--house load transients of Qinshan Phase II 600 MW nuclear power plant. The simulating results show that all of the reactor main parameters are operating in the allowable ranges, the reactor system is stable, and the control characteristics of the nuclear power plant is satisfactory. They are also good in agreement with Framatome's results

Prioritized rule based load management technique for residential building powered by PV/battery system

Directory of Open Access Journals (Sweden)

T.R. Ayodele

2017-06-01

Full Text Available In recent years, Solar Photovoltaic (PV system has presented itself as one of the main solutions to the electricity poverty plaguing the majority of buildings in rural communities with solar energy potential. However, the stochasticity associated with solar PV power output owing to vagaries in weather conditions is a major challenge in the deployment of the systems. This study investigates approach for maximizing the benefits of a Stand-Alone Photovoltaic-Battery (SAPVB system via techniques that provide for optimum energy gleaning and management. A rule-based load management scheme is developed and tested for a residential building. The approach allows load prioritizing and shifting based on certain rules. To achieve this, the residential loads are classified into Critical Loads (CLs and Uncritical Loads (ULs. The CLs are given higher priority and therefore are allowed to operate at their scheduled time while the ULs are of less priority, hence can be shifted to a time where there is enough electric power generation from the PV arrays rather than the loads being operated at the time period set by the user. Four scenarios were created to give insight into the applicability of the proposed rule based load management scheme. The result revealed that when the load management technique is not utilized as in the case of scenario 1 (Base case, the percentage satisfaction of the critical and uncritical loads by the PV system are 49.8% and 23.7%. However with the implementation of the load management scheme in scenarios 2, 3 and 4, the percentage satisfaction of the loads (CLs, ULs are (93.8%, 74.2%, (90.9%, 70.1% and (87.2%, 65.4% for scenarios 2, 3 and 4, respectively.

Fuzzy Adaptive Particle Swarm Optimization for Power Loss Minimisation in Distribution Systems Using Optimal Load Response

DEFF Research Database (Denmark)

Hu, Weihao; Chen, Zhe; Bak-Jensen, Birgitte

2014-01-01

Consumers may decide to modify the profile of their demand from high price periods to low price periods in order to reduce their electricity costs. This optimal load response to electricity prices for demand side management generates different load profiles and provides an opportunity to achieve...... power loss minimization in distribution systems. In this paper, a new method to achieve power loss minimization in distribution systems by using a price signal to guide the demand side management is proposed. A fuzzy adaptive particle swarm optimization (FAPSO) is used as a tool for the power loss...

Effects of load on ground reaction force and lower limb kinematics during concentric squats.

Science.gov (United States)

Kellis, Eleftherios; Arambatzi, Fotini; Papadopoulos, Christos

2005-10-01

The purpose of this study was to examine the effects of external load on vertical ground reaction force, and linear and angular kinematics, during squats. Eight males aged 22.1 +/- 0.8 years performed maximal concentric squats using loads ranging from 7 to 70% of one-repetition maximum on a force plate while linear barbell velocity and the angular kinematics of the hip, knee and ankle were recorded. Maximum, average and angle-specific values were recorded. The ground reaction force ranged from 1.67 +/- 0.20 to 3.21 +/- 0.29 times body weight and increased significantly as external load increased (P squat exercises is not achieved at the same position of the lower body as external load is increased. In contrast, joint velocity coordination does not change as load is increased. The force-velocity relationship was linear and independent from the set of data used for its determination.

Experimental and numerical investigation of slabs on ground subjected to concentrated loads

Science.gov (United States)

Øverli, Jan

2014-09-01

An experimental program is presented where a slab on ground is subjected to concentrated loading at the centre, the edges and at the corners. Analytical solutions for the ultimate load capacity fit well with the results obtained in the tests. The non-linear behaviour of the slab is captured by performing nonlinear finite element analyses. The soil is modelled as a no-tension bedding and a smeared crack approach is employed for the concrete. Through a parametric study, the finite element model has been used to assess the influence of subgrade stiffness and shrinkage. The results indicate that drying shrinkage can cause severe cracking in slabs on grade.

Power loads in the limiter phase of Wendelstein 7-X

Energy Technology Data Exchange (ETDEWEB)

Niemann, Holger; Jakubowski, Marcin; Sunn Pedersen, Thomas [Max-Planck-Institut fuer Plasmaphysik, Greifswald (Germany); Wurden, Glen [Los Alamos National Laboratory, Los Alamos (United States)

2016-07-01

Wendelstein 7-X (W7-X), an advanced stellarator with five-fold symmetry, will start its initial plasma operation phase(OP1.1) in December 2015. In OP1.1 the plasma-wall interaction is realized with 5 graphite limiters installed on the inboard side of the plasma vessel, which should efficiently intercept >99% of the convective plasma heat load at the plasma edge with the chosen magnetic configuration. Assuming an even distribution of power loads among all 5 limiters, discharges with 2 MW of ECRH heating power could be run for up to a second. Calculations shows typical three separate helical magnetic flux bundles of different connection length in the order of a few tens of meters. These form 3-D structure of magnetic footprints results in localized peaks in the limiter power deposition patterns. The heterogenous temperature distribution pattern will be investigated with two IR cameras. The heat flux density will be evaluated with the THEODOR code from evolution of the surface temperature data. Together with two sets of Langmuir probes in module 5 this provides enough data to resolve experimentally different channels of heat transport towards the limiter in OP1.1 plasmas. Additionally, the obtained data will be compared against the output of EMC3-Eirene calculations to identify the channels of energy transport at the plasma boundary in the first operation phase of W7-X.

Demand Response Load Following of Source and Load Systems

DEFF Research Database (Denmark)

Hu, Jianqiang; Cao, Jinde; Yong, Taiyou

2017-01-01

This paper presents a demand response load following strategy for an interconnected source and load system, in which we utilize traditional units and population of cooling thermostatically controlled loads (TCLs) to follow the mismatched power caused by the load activities and the renewable power...... injection in real time. In the demand side of power systems, these TCLs are often affiliated to a bus load agent and can be aggregated to multiple TCL aggregators. Firstly, aggregate evaluation of the TCL aggregator is carried out based on a bilinear aggregate model so as to derive the available regulation...

Effect of Enhanced Air Temperature (extreme heat, and Load of Non-Linear Against the Use of Electric Power

Directory of Open Access Journals (Sweden)

I Ketut Wijaya

2015-12-01

Full Text Available Usage Electric power is very easy to do, because the infrastructure for connecting  already available and widely sold. Consumption electric power is not accompanied by the ability to recognize electric power. The average increase of electricity power in Bali in extreme weather reaches 10% in years 2014, so that Bali suffered power shortages and PLN as the manager of electric power to perform scheduling on of electric power usage. Scheduling is done because many people use electric power as the load  of fan and Air Conditioner exceeding the previous time. Load of fan, air conditioning, and computers including non-linear loads which can add heat on the conductor of electricity. Non-linear load and hot weather can lead to heat on conductor so  insulation damaged  and cause electrical short circuit. Data of electric power obtained through questionnaires, surveys, measurement and retrieve data from various parties. Fires that occurred in 2014, namely 109 events, 44 is  event caused by an electric short circuit (approximately 40%. Decrease power factors can cause losses of electricity and hot. Heat can cause and adds heat on the  conductor electric. The analysis showed  understanding electric power of the average  is 27,700 with value between 20 to 40. So an understanding of the electrical power away from the understand so that many errors because of the act own. Installation tool ELCB very necessary but very necessary provide counseling   of electricity to the community.

Tuning of PID load frequency controller for power systems

International Nuclear Information System (INIS)

Tan Wen

2009-01-01

PID tuning of load frequency controllers for power systems is discussed in this paper. The tuning method is based on a two-degree-of-freedom internal model control (IMC) design method, and the performance of the resulting PID controller is related to two tuning parameters thus detuning is easy when necessary. Then an anti-GRC scheme is proposed to overcome the generation rate constraints. Finally, the method is extended to two-area cases.

Behavior of a nuclear power plant ventilation stack for wind loads

International Nuclear Information System (INIS)

Venkatachalapathy, V.

2012-01-01

This paper describes behavior of self supporting tall reinforced concrete (RC) ventilation stack of a nuclear power plant (NPP) for wind loads. Since the static and equivalent dynamic wind loads are inter-dependant on overall size of the stack, proper sizing of the stack geometry is important for reducing wind loads. The present study investigated the influence of engineered backfill soil on lateral response of ventilation stack. Ignoring backfill soil stiffness up to ground height does not allow to predict actual critical wind velocity causing across wind oscillation. The results show that proposed modification in the stack geometry modeled using 2D beam-spring elements is economical than that of single tapered geometry. Shaft diameter reduced in the proposed geometry indicates that there is a scope for overall space savings in the NPP layout. (author)

Power quality improvement in highly varying loads using thyristor-switched capacitor

Energy Technology Data Exchange (ETDEWEB)

Poshtan, M. [Petroleum Inst., Abu Dhabi (United Arab Emirates). Dept. of Electrical Engineering; Mokhtari, H.; Esmaeili, A. [Sharif Univ. of Technology, Tehran (Iran, Islamic Republic of). Dept. of Electrical Engineering

2007-07-01

Ordinary contactor-based-capacitor (CBC) banks may not be able to response quickly enough in highly varying electrical loads such as welding machines or arc furnace loads. Thyristor-switched capacitor (TSC) banks are therefore used to compensate for reactive power of highly varying loads. In this paper, the performance of a TSC was compared to CBC banks. The 2 systems, were also compared in terms of energy saving in transmission systems. Simulations carried out using PSCAD/EMTDC software showed that there was a considerable difference in the performance of the 2 systems. The shortcomings of existing CBC systems include slow response of mechanical switching systems; problem of switching more than one bank into the system; and, voltage/current transients during on-off switching. 3 refs., 6 tabs., 14 figs.

Hysteresis Control for Shunt Active Power Filter under Unbalanced Three-Phase Load Conditions

Directory of Open Access Journals (Sweden)

Z. Chelli

2015-01-01

Full Text Available This paper focuses on a four-wire shunt active power filter (APF control scheme proposed to improve the performance of the APF. This filter is used to compensate harmonic distortion in three-phase four-wire systems. Several harmonic suppression techniques have been widely proposed and applied to minimize harmonic effects. The proposed control scheme can compensate harmonics and reactive power of the nonlinear loads simultaneously. This approach is compared to the conventional shunt APF reference compensation strategy. The developed algorithm is validated by simulation tests using MATLAB Simulink. The obtained results have demonstrated the effectiveness of the proposed scheme and confirmed the theoretical developments for balanced and unbalanced nonlinear loads.

Radial basis function neural network for power system load-flow

International Nuclear Information System (INIS)

Karami, A.; Mohammadi, M.S.

2008-01-01

This paper presents a method for solving the load-flow problem of the electric power systems using radial basis function (RBF) neural network with a fast hybrid training method. The main idea is that some operating conditions (values) are needed to solve the set of non-linear algebraic equations of load-flow by employing an iterative numerical technique. Therefore, we may view the outputs of a load-flow program as functions of the operating conditions. Indeed, we are faced with a function approximation problem and this can be done by an RBF neural network. The proposed approach has been successfully applied to the 10-machine and 39-bus New England test system. In addition, this method has been compared with that of a multi-layer perceptron (MLP) neural network model. The simulation results show that the RBF neural network is a simpler method to implement and requires less training time to converge than the MLP neural network. (author)

Advances in electric power and energy systems load and price forecasting

CERN Document Server

2017-01-01

A comprehensive review of state-of-the-art approaches to power systems forecasting from the most respected names in the field, internationally. Advances in Electric Power and Energy Systems is the first book devoted exclusively to a subject of increasing urgency to power systems planning and operations. Written for practicing engineers, researchers, and post-grads concerned with power systems planning and forecasting, this book brings together contributions from many of the world’s foremost names in the field who address a range of critical issues, from forecasting power system load to power system pricing to post-storm service restoration times, river flow forecasting, and more. In a time of ever-increasing energy demands, mounting concerns over the environmental impacts of power generation, and the emergence of new, smart-grid technologies, electricity price forecasting has assumed a prominent role within both the academic and industrial ar nas. Short-run forecasting of electricity prices has become nece...

Finance considerations relating to power station construction from the viewpoint of a European banker

International Nuclear Information System (INIS)

Junker, H.J.

1990-01-01

The energy industry in the European Community is outlined in brief in the first section. It includes a description of the structure and organization of the various companies operating power stations, featuring such keywords as centralized-decentralized and shareholding. The general considerations of the banking sector are then dealt with. From the banker's point of view, the risk factor of a loan depends on whether the load is to be used for the financing of a brand new power station based either on fossil fuels, nuclear power or alternative sources of energy or whether the load is to be used for modernization purposes. In this respect the credit rating of the borrower, including shareholders, profitability, capital investment volume in relation to company size, project risk and methods of furnishing security shall be discussed. Having dealt with these basic questions, the specific factors relating to financing for modernization purposes are examined. A distinction must be made between voluntary and mandatory modernization measures. The assessment of modernization required by law is generally based on whether the mandatory standards an be fulfilled by investing the least possible expenditure. On the other hand, the banker assesses voluntary modernization mainly in light of the resulting effects on the financial standing of the borrower. If satisfactory results are achieved from the examination of these points, the question of security must be considered when evaluating the residual exposure. All considerations culminate in the selection of the appropriate form of financing. In addition to the traditional bank loan and project financing, government support and special forms of financing are also discussed

The geochemistry of the Yangtze River: Seasonality of concentrations and temporal trends of chemical loads

Science.gov (United States)

Müller, Beat; Berg, Michael; Pernet-Coudrier, Benoã®T.; Qi, Weixiao; Liu, Huijuan

2012-06-01

The Yangtze is the largest river in Asia and its water composition reflects the activities of about 400 Mio people in its catchment. Its chemical loads have a large impact on the biogeochemistry of the East China Sea. We discuss and quantify the annual dynamics of major ions, nutrients, and trace elements from samples collected monthly at Datong Station from May 2009 to June 2010. The Yangtze today carries 192 × 106 tons of total dissolved solids annually to the East China Sea, which is an increase of 25% compared to the average of 1958-1990. While the loads of dissolved silica (SiO2), dissolved inorganic carbon (DIC), Ca2+ and Mg2+compared well with the long-term averages since the 1950s, loads of Na+, Cl-, SO42-, have tripled since 1958-1990. The increase of SO42- is attributed to the burning of coal in the catchment, and 18% of the F- load is estimated to originate from this source. The increase of Na+ and Cl-loads may be anthropogenic as well. The load of dissolved inorganic nitrogen (DIN) has increased 15 fold since the early measurements around 1970 and amounts to 1.6 Mt-N/yr today. The particulate concentrations of the typical anthropogenic trace metals Cd, Cr, Cu, Ni, Pb, and Zn showed enrichment factors between 0.7 - 7 compared to the natural background. Their annual peak concentrations all exceeded the quality targets recommended by the EC up to two times. However, the load of trace elements at Datong decreased by 73-86% (As: 50%) in the past ten years.