same AC voltage source, the inductor absorbs energy during the same “half cycle” that the capacitor is giving energy. And similarly, the inductor produces energy during the same “half cycle” that the capacitor absorbs energy. Neither of them absorbs any real power over one complete cycle. Thus, when a motor needs reactive power, it is not necessary to go all the way back to electric power generators on the transmission grid to get it. You can simply put a capacitor at the location of the motor and it will provide the VARs needed by the motor. This relieves the generator and all the lines between the generator and the motor of having to transmit those VARs. They are provided “locally” by the capacitor. This means that with the capacitors installed, the current in the lines will be smaller than when the capacitors are not installed. This is a good thing because current in the lines causes heat and every line can only handle a limited amount of current. Since the line current is smaller when the capacitors are installed, the voltage drop along all the lines is also less, making it more likely that the motor will have a voltage closer to the desired value. When there are not enough VARs flowing locally to the loads, the generators must supply them remotely, causing unnecessarily large currents and a resulting drop in voltage everywhere along the path.
The Deputy Director supports the mission of the PowerSystemsEngineeringResearchCenter National Science Foundation Industry/University Cooperative ResearchCenter with thirteen university powerengineering programs working with almost 40 industry and government members (1) to find innovative solutions to challenges in electric powersystems, markets, and transmission and distribution technologies, and (2) to educate the next generation of powerengineering professionals. PSERC also receives funding from the U.S. Department of Energy for research in electric powersystems and markets. PSERC has about 15 on-going research projects principally supporting about 50 graduate students working for about 25 university researchers. The PSERC university research community has about 75 members in powerengineering, economics, industrial organization, operations research, computer science, etc.
The PowerSystemsEngineeringResearchCenter (PSERC) is a multi-university Center conducting research on challenges facing the electric power industry and educating the next generation of power engineers. More information about PSERC can be found at the Center’s website: http://www.pserc.org.
Center of Excellence on Applied Electromagnetic Systems and Advanced Motion SystemsResearch Laboratory, School of Electrical and Computer Engineering, University of Tehran, Tehran, Iran Abstract—In high power applications of wireless power transfer systems as Maglev, both a high transferred power and a high efficiency are essential. However, these two requirements usually show dissimilar profiles over a range of operating conditions. Magnetic and electric models for a capacitor compensated system are used to analyze the problem. Using the analysis outcome, a compromise is made to come to an acceptable design achieving both requirements. In particular, appropriate design parameters and resonance frequency are obtained. The analytical results are confirmed by 3D FEM analysis.
The purpose of the Department of Technology and Information’s (DTI) Enterprise Disaster Recovery Test was to simulate an IT infrastructure outage due to an F3 tornado that leveled Delaware government’s data center which supports the entire State. The outage affected the enterprise Public Safety, Financial, Pension, and Payroll/ Human Resource Systems, GIS, and Mainframes. The following support systems were also scheduled for recovery in support of this exercise: Disaster Recovery Master Server, Terminal Server for remote access, Virtual Server Environment, Enterprise Tape Backup System, Extensible Markup Language Firewall Environment (XML), and Secure File Transfer Protocol server. The Enterprise Disaster Recovery Test occurred at our Hot Site provider SunGard
As a strictly selected abstract database, Web of Science (WoS), including Science Citation Index Expanded, Social Sciences Citation Index, and Arts and Humanities Citation Index, has long been recognized as the most authoritative scientific and technical literature indexing tool providing data on the most important areas in science and technology research, especially about medicine. Fur- thermore, the WoS database includes the world’s most im- portant journals in relation to healthcare science, health policy, and systemsresearch. The majority of high quality articles on healthcare science research are indexed by WoS. In addition, as a citation database, WoS provides enough search fields, such as keywords, country, organization, au- thor, and references, which are all very important for litera- ture analysis, especially for scientometric analysis [24,25]. Therefore, we conducted a systematic search through the WoS database. The search strategy has been built on previ- ous literature reviews with similar objectives [10,13,26-28], with further refinements and iterative testing of individual search terms. The six building blocks of health systems, as defined by the WHO, were used to define the scope of this search (details of search terms and the search strategy are available in Additional file 1). Literatures were included if they met the following criteria: for the purpose of this study, HSR included the system-level research directly tar- geting one or more of the six health system building blocks and their sub-components as defined by the WHO. A total of 35,819 publications were identified from 1900 to 2012. The retrieved papers were downloaded from WoS as text files and were converted to a database using the Thomson Data Analyzer, which was also used to clean and analyze data. Papers originating from England, Scotland, Northern Ireland, and Wales were grouped under the United Kingdom heading, while those from Hong Kong, Macao, and Taiwan were categorized each independently and are not included under the China heading.
In recent years electricity has been used to power more sophisticated and technically complex manufacturing processes, and a variety of high-technology consumer goods. These products and process are sensitive not only to the continuity of power supply but also on the quality of power supply such as voltage and frequency. In power system, both active and reactive power demands are never steady they continuously change with the rising or falling trend. The changes in real power affect the system frequency, while reactive power is less sensitive to changes in frequency and is mainly dependent on Changes in voltage magnitude . Load Frequency Control (LFC) as a major function of Automatic Generation Control (AGC) is one of the important control problems in electric power system design and operation. It is becoming more significant today because of the increasing size, changing structure, emerging new uncertainties, environmental constraints and the complexity of powersystems. A large frequency deviation can damage equipment, corrupt load performance, reason of the overloading of the transmission lines and can interfere with system protection schemes, ultimately leading to an unstable condition for the electric power system . Although the active power and reactive power have combined effects on the frequency and voltage, the control problem of the frequency and voltage can be decoupled. The frequency is highly dependent on the active power while the voltage is highly dependent on the reactive power. Thus the control issue in powersystems can be decoupled into two independent problems. One is about the active power and frequency control while the other is about the reactive power and voltage control .Many investigations in the area of LFC of an isolated power system have been reported and a number of control schemes like integral (I), Proportional and Integral (PI), Proportional, Integral and Derivative (PID) control have been proposed to achieve improved performance [4-7].Fuzzy -PI controllers have been proposed to solve Load Frequency Control problems, and developed different fuzzy rules for the proportional and integral gains separately. in this paper three case studies of Fuzzy -PI controllers different tuning of PI controller. The comparison results suggest that the overshoots and settling time with the proposed Fuzzy -PI controllers’ controller was better.
Sandwich boards(panels) have been effectively utilized for a long time as a part of the avionics and aviation businesses, and in marine, and mechanical and structural designing applications. This is because of the chaperon high firmness and high quality to weight proportions of sandwich frameworks. The utilization of the sandwich developments in the aviation structures can be followed back to Second World War when English De Havilland Mosquito aircraft had used the sandwich developments . In the early utilize, the sandwich structure was exceptionally basic in development, with basic material, fabric or flimsy metal facings were utilized and delicate wood were utilized as the center.
The Flexible Alternating Current Transmission Systems (FACTS) device deals with the control of power flow, alternating current of transmission line and immediately respond towards the stability problems of the system. The present paper show that how the FACTS device STATCOM enhance the dynamic response and voltage flicker in distribution network of the powersystems. In MATLAB a simplified distribution system is modeled and the find out the desired objectives. D-STATCOM changes from inductive to capacitive operation, the modulation index of the PWM inverter is increased from 0.56 to 0.9 which corresponds to a proportional increase in inverter voltage. Reversing of reactive power is very fast, about one cycle, as observed on D-STATCOM current. Observed on Scope that voltage fluctuation at bus B3 is now reduced to +/- 0.7 %. The D-STATCOM compensates voltage by injecting a reactive current modulated and varying between 0.6 pu capacitive when voltage is low and 0.6 pu inductive when voltage is high.
The Center for Transportation Research and Education (CTRE) has conducted studies on the use of added law enforcement in work zones and found that added enforcement always ranks as the most effective strategy for reducing speeds through work zones and controlling errant, reckless, and aggressive driving behavior (Kamyab et al. 2003). The Work Zone Safety Toolbox, produced by the Maryland State Highway Administration, provides the primary reasons for using police in work zones: police presence encourages speed control, the presence of the police alone increases motorists’ compliance with work zone signage and discourages aggressive or careless driving, and officers can quickly respond to incidents in the work zone and direct traffic in an efficient manner (Maryland SHA 2005). The presence of a uniformed officer can also encourage greater motorist alertness to his/her surroundings, which leads to a better compliance with the traffic control signs. The Toolbox also states that speeds are decreased upstream and at the location of the officer, while the speeds often increase again downstream. In addition, the percentage of traffic merging in advance of the lane closure is increased.
As probably the most severecause of malfunctioning of grid-connected equipment is unbalancedvoltage sags, this is the usual source of abnormalsituations considered in these studies. Voltage sags typicallytend to deteriorate the performance of the power convertersand electrical machines connected to the ac network. Inparticular, a re- duction of the power quality is noticed in thisequipment, which is caused by a ripple in the output power andan increase in the current harmonic distortion.Several con- trolschemes have been recently introduced to cope with theseproblems. Voltage deviations were reduced in the ac network byinjecting negative-sequence reactive power. A coordinatedcontrol that supplies both positive-sequence and negativesequencereactive power was introduced. This studyreveals that it is possible to simultaneously cor- rect the deviationin the positive-sequence voltage and at- tenuate the negativesequencevoltage to a preset value.The theoreticallimits of the reactive power delivered to the ac network wereestablished in order to ensure that the max- imum output currentis not exceeded during the voltage sag, thus guaranteeing a safeSTATCOM operation. The interesting results presented in this paper were extended to other reactive power controlstrategies.
A multiple project scenario at the enterprise level is shown in Figure 4. The top tasks are systemsengineering service tasks that support the three software projects below it. The initial tasks numbered 1.0, 2.0 and 3.0 are project initiation tasks. The other tasks are in continuous support of software engineering who has “kicked back” some tasks requiring more work. These tasks are numbered the same in both swim lanes (e.g. Task 2.2, Task 3.2, etc.)
Recent policy developments within the electricity supply industry have favoured the development of renewable technologies, as demonstrated by the UK Government’s recent 'Energy White Paper' [UK Government, 2003] and the Scottish Executive’s 'Securing a Renewable Future' publication [Scottish Executive, 2003]. These set aspirational targets of 20% and 40% respectively for the generation of electricity from renewable sources by 2020. Since the current economically viable renewable sources are stochastic in nature (e.g. wind power), achieving these targets will result in higher levels of vulnerability within the electrical supply network. This, in turn, will increase the levels of control and reserve plant required to prevent supply disruption. In an effort to address this undesirable situation, more predictable renewable energy technologies require to be developed. Tidal current technology has been identified as an important contributor because the energy yield and time of occurrence may be predicted in advance. Further, by arranging for the strategic location of tidal power generation systems at several locations, a continuous base load power supply should be achievable. This latter attribute is important, as sufficient base load supply is crucial to maintaining electrical network integrity. It is for
The idea of the systems engineer came about as a result of the ever increasing complexity of technical systems. It is now commonly assumed that a “systems engineer” refers to an information/computer technologist who maintains a computer or communications network, however the title has a broader connotation in the historical sense. System engineering focuses on defining customer needs early in the project or product design cycle, and considers the complete problem: operations, environment, design, development, manufacturing, deployment, cost and schedule, performance, training, maintenance, test and disposal . Historically the practice of having a product or project manager oversee the aforementioned items has been the norm; however it is becoming more common to expect the technologist to take responsibility for an increasing number of these items.
Horizontal boreholes existed for draining methane, a method established some years ago . This was essential because of the highly gassy nature of the coal at Pike, which in turn was a consequence of the faulted geology causing encapsulated compartments of coal. Ideally the boreholes would be orientated to pre-drain the methane ahead of mining. However this was not the case because the mine was simultaneously in an exploratory phase and a production phase. Consequently the exploratory boreholes tended to become intersected by subsequent cutting of roadways or of hydromining. This liberated additional methane above that of the mining itself. The methane drainage systems were generally inadequately implemented, and there were many cases where bores had been freely venting to roadways. This issue was known to the mine, since workers and various consultants had identified this as a deficiency. The gas drainage system was at capacity, and sometimes unable to cope. Important maintenance actions such as dewatering were not conducted reliably. In some locations in the mine a substantial volume of methane was freely vented by boreholes. On the day of the accident one of the most in-bye work-crews was cutting a roadway, and progress was delayed because the tunnel intersected a borehole.
Biomass is second to hydropower as a leader in renewable energy production. Biomass has an existing capacity of over 7,000 MW. Biomass as a fuel consists of organic matter such as industrial waste, agricultural waste, wood, and bark. Biomass can be burned directly in specially designed power plants, or used to replace up to15% of coal as a fuel in ordinary power plants. Biomass burns cleaner than coal because it has less sulfur, which means less sulfur dioxide will be emitted into the atmosphere. Biomass can also be used indirectly, since it produces methane gas as it decays or through a modern process called gasification. Methane can produce power by burning in a boiler to create steam to drive steam turbines or through internal combustion in gas turbines and reciprocating engines.