The various nonlinear loads like Adjustable Speed Drives (ASD’s), bulk rectifiers, furnaces, computer supplies, etc. draw non sinusoidal currents containing harmonics from the supply which in turn causes voltage harmonics. Current harmonic causes increased power system losses, excessive heating in rotating machinery, interference with nearby communication circuits and control circuits, etc. It has become a vital importance to maintain the sinusoidal nature of voltage and currents in the power system. Various international agencies like IEEE and IEC have issued standards, which put limits on various current and voltage harmonics. The limits for various current and voltage harmonics specified by IEEE-519 for various frequencies are given in Table 2.1 and Table 2.2. Table 2.1 IEEE 519 Voltage Limits Bus Voltage Minimum Individual Harmonic Components (%) Maximum THD (%) 69 kV and below 3 5 115 kV to 161 kV 1.5 2.5 Above 161 kV 1 1.5 The objectives and functions of active power filters have been expanded from reactive power compensation, voltage regulation, etc. to harmonic isolation between utilities and consumers, and harmonic damping throughout the distribution as harmonics propagate through the system. Active power filters are either installed at the individual consumer premises or at substation and/or on distribution feeders. Depending on the compensation objectives, various types of active power filter topologies have evolved, a proper briefing of which is provided in [3-4]. Table 2.2 IEEE 519 Current Limits SCR=Isc/Il h<11 11 to 17 17 to 23 23 to 35 35 <20 4.0 2.0 1.5 0.6 0.3 5.0 20 – 50 7.0 3.5 2.5 1.0 0.5 8.0 50 -100 10.0 4.5 4.0 1.5 0.7 12.0 100 – 1000 12.0 5.5 5.0 2.0 1.0 15.0 >1000 15.0 7.0 6.0 2.5 1.4 20.0... ... middle of paper ... ... IP is captured and "stored" until the next sample of IP is obtained to replace the old one. This action is executed with the help of "Sample and Hold" circuits, which are synchronized with the synchronization pulses to trigger the S&H are generated through the "zero-crossing" signals, obtained from the set of "in-quadrature voltages". These "in-quadrature voltages" are generated in the control block with the DZ0 connection, signal transformer. The control circuit is also has the capability to avoid flickers and transient phenomena in the source, produced by sudden changes in load current. To do this, control system makes soft variation of IP during these moments. However, this action will require to have the energy storage components in the APF. Hence the design of the control system has to take in account the characteristics of the power filter.
Muller, S., Prowse, D. L., & Soper, M. E. (2012, September 25). CompTIA A+ Cert Guide: Power Supplies and System Cooling | Foundation Topics | Pearson IT Certification. Retrieved March 20, 2014, from http://www.pearsonitcertification.com/articles/article.aspx?p=1945640
The first method of insuring a correct reading is obtained is through using one wattmeter on a balanced load. Using this on an unbalanced load will lead to an inaccurate reading for power. To complete this method a reading with a wattmeter connected from a single line to neutral via the voltage probes and in line with the line on the current probes. By multiplying the value of the wattmeter by three the total system power is found.
COMP09022 Network Design BSc COMPUTER NETWORKING COMP09022 ICMPv6 Prepared by B00270675 13-03- 2015 WORD COUNT (0000) TABLE OF CONTENTS TITLE PAGE……………………………………………... 1 TABLE OF CONTENTS………………………………….. 2 INTRODUCTION TO THE REPORT……………………. 3 TABLE OF FEATURES.......................................................4
After compression, the structure data, audio and video must be multiplexed. A number of compressed TV signals are combined by a multiplexer and put unto a shared transition medium. This is done by one of the two possible kinds of multiplexers that result in either a transport or a program stream, which is suited for secure transmission paths since it can contain large amounts of information. In addition multiplexing can be done using various methods. Time division multiplexing allocates a distinct time interval for each channel in a set; with the help of synchronization and a fixed interval order the channels take turns using the common line.
It also requires a protection system in which the sources are interfaced using power electronics, so it definitely needs unique protective solutions to provide functionality. [CERTS03]
· B-phase transformer (EMTU-TT01) · Feedback electronic wattmeter · Multi-range moving-iron ammeter · Instrument voltage transformer THEORY AND INTRODUCTION ----------------------- Transformers are used all over the world to step-up and step-down electricity. The transformer is one of the most commonly used electrical devices. The reason the transformer is so popular is because they range in size from 240V to well over 240kV, stepping -up and stepping-down electricity all over the world.
In this paper, I will examine fundamental elements of a conductor’s relationship
For the prevantion of the electricity blackout we need to build smart power grid. A modernized electrical grid that uses analog or digital information and communications technology to gather and act on information, such as information about the behaviours of suppliers and consumers is known as a smart grid. This is used to improve the efficiency, reliability, economics, and sustainability of the production and distribution of electricity in an automated fashion[12]. The important aspects of smart grid is to electronic power conditioning and control of the production and distribution of
As the conductor rotates toward 90 degrees, the component of horizontal velocity becomes. greater, thus generating a higher voltage. The voltage starts from zero, increases in a. positive direction to a maximum value at 90 degrees, decreases to zero at 180 degrees. increases in the opposite or negative direction until it attains a maximum negative value at 270 degrees, and finally decreases to zero value again at 360 degrees. It follows, then, that the induced emf can be completely described by the relation.
4.Mr.Nilay N. Shah: Assistant Professor of SARDAR VALLABHBHAI PATEL INSTITUTE OF TECHNOLOGY,GTU.SINCE 2004. HE IS CURRENTLLY PURSING PH.D AND HIS RESEACH AREA ARE POWER SYSTEM DYNAMICS, FACTS , POWER SYSTEM PROTECTION AND ELECTRICAL MACHINE.
My undergraduate studies got me interested in the application of mathematics in engineering and I topped the subject in my second year of engineering and was also a University Rank Holder (9th). Mathematics simplifies concepts into numbers, constants, variables and equations and that helps to predict some complex outcomes. A power system per se is a simple set of interconnected electrical and mechanical components, but their unified behavior is a very complex phenomenon. Efficient generation, transmission, distribution and usage of electric power require thorough understanding of this network behavior. Increasing power demands and meshing of multiple & complex networks into super grids demand superior system designs and ultimate built in operational control. Without mathematics, this engineering complexity cannot be analyzed, ...
Alternating current is always changing in direction and amplitude. The current flow in alternating current changes in even intervals. Ac usually changes in power and direction. The vast majority of power supplied for households and big business is alternating current. This is because of the ease of generating alternating current in alternators. The main concept of alternators is moving a conductor through magnetic lines. The change in the magnetic field around the conductor or vice versa makes electrons move. When you have physically moved either the conductor or magnet in a complete 306-degree circle you have produced one sine wave or one complete cycle. The amount of time it takes to complete one cycle is referred to as a period. The frequency of an alternating sine wave is the amount of cycles per second. Frequency is measured in hertz. One hertz is equivalent to one cycle per second. The frequency coming out of your electrical plug at home is 60 Hz. The peak value in a sine wave is the top voltage level away from zero. The peak-to-peak voltage value is referring to difference between the positive peaks value to the negative peak value. The effective or rms value of a sine wave is the actual amount you would use or measure using a multi-meter. In three-phase alternating current there are three different coils or conductors that produce three different sine waves.
...into an expert power systems researcher. I long for a total comprehension of power systems operation, and I believe that obtaining a PhD in power systems engineering is a first step. Through intensive research, I plan to contribute to the technological advancement of the power systems industry. By working with the Nigerian Electricity Regulatory Commission (NERC), I plan to use my expertise to facilitate the much needed change in the Nigerian power sector. After studying the research interests and outstanding achievements of professors like: George Gross, Philip T. Krein, Thomas J. Overbye, Peter W. Sauer and Alejandro Dominguez-Garcia, I am certain that, in the University of Illinois at Urbana-Champaign, I can acquire the skill set and technical knowledge necessary to realize my career goals. I hope to both contribute and grow in its research-friendly environment.
This report will describe the two forms of data communications in terms of the physical interfaces and modes of operation. It will describe the features of data communications equipment in relation to synchronous and asynchronous communication including modems, network terminating units and sending and receiving equipment.
It converts the mechanical energy of the rotating shaft caused by wind into electrical energy (Correla, 1986). The focus of this research will be limited to devices that operate as electrical motors.... ... middle of paper ... ...