When the two port ne twork is linear and has no d epende nt sources, the transfer impedances are equal z 12 z 21, and the two. Pdf two port networks lecture for students introduction. Example problem a 220kv, 150 mva, 60hz, threephase transmission line is 140 km long. A transmission line may have at its end an impedance, z, which is not equal to the characteristic impedance of the line 2. For high frequencies, it is convenient to describe a given network in terms of wavesrather than voltages or currents.
The electrical power is transmitted over a transmission line with a speed of light that is 3x10. Calculate the line inductancemeter and capacitance meter. An electric transmission line has four parameters, namely resistance. Generalized reflection coefficient, smith chart, passives. Lecture outline transmission lines slide 2 introduction transmission line equations transmission line wave equations transmission line parameters and characteristic impedance, z0 special cases of transmission lines general transmission lines lossless lines weakly absorbing lines distortionlesslines. Niknejads book or pozar, gonzalez, collin, etc ee142fall 2010 10 infinite ladder. Thats why 10 years ago digital designers didnt use transmission lines. Transmission line parameters if we consider an infinite lossless transmission line, we can determine the inductance l and capacitance c per unit length from geometric field considerations. Transmission lines are used in power distribution at low frequencies, and in communications at high frequencies. These parameters are uniformly distributed along the line. The term line parameters refer to the inherent series resistance and inductance that is found on transmission lines. We will see that these four parameters are calculated from 1 the line. One transmission line at this high voltage was built near chicago as part of the interconnection for three large nuclear power plants southwest of the city.
However, if the size of the circuit zis very small compared to the wavelength of the signal on the transmission line, it becomes an accurate and effective way to model the transmission line. Coupling between transmission linescoupling between transmission lines now consider a zerosequence component i 02. Lecture notes on power system engineering ii vssut. Since our electrical components are defined in unit length, the total values can be found by multiplying the unit length value by dx. Lecture series on power system generation, transmission and distribution by prof. A wider conductor gives lower impedance as would be expected. The three physical embodiments that are of interest are the twowire transmission line, the coaxial transmission and.
More over, a deeper study about these parameters is undertaken here, by varying the frequency and the conductivity of the overhead lines and seeing how this variation affects the final results. Lei wu department of electrical and computer engineering. Each line element has its own value, and it is not possible to concentrate or lumped them at discrete points on the line. Transmission line design information in these notes, i would like to provide you with some background information on ac transmission lines. If you have watched this lecture and know what it is about, particularly what electrical engineering topics are discussed, please help us by commenting on this video. Its major function is to transport electric energy, with minimal losses, from the power sources to the load centers, usually separated by long distances. In a tmodeled mediumtransmissionline,thelinecapacitances. A transmission line consists of two or more parallel conductors used to connect a source to a load. Assuming ex,t 2cos3x1015t 10 7x vm, calculate the wave velocity. Since the phases of a highvoltage overhead transmission line must be spaced further apart to ensure proper insulation, a highvoltage line will have a higher inductance than a lowvoltage line. In overhead transmission lines, the conductors are suspended from a pole.
The theory of distributed circuits transmission lines bridges circuit theory. Power loss due to corona, practical importance of corona, use of bundled conductors in e. The design of a transmission line depends on four electrical parameters. Solution of the differential equations describes how signals propagate, and leads to the extraction of a. Lei wu department of electrical and computer engineering ee 333 power systems engineering. Ee261 lecture notes electronic montana state university. For microwave integrated circuits mics planar transmission lines such as the microstrip line have become very important. Twoport equivalent circuit using impedance parameters. An example of an electric power system is the network that supplies a regions homes and industry with powerfor sizable regions, this power. Hon tat hui transmission lines basic theories nusece ee2011 28 example 1 a 100.
The power transmission line is one of the major components of an electric power system. These four parameters are uniformly distributed along the whole line. We will have a brief introduction to help us understand some of the other concepts smith chart and sparameters. Lecture description this video lecture, part of the series power system generation by prof.
Ac transmission line impedance parameters ac transmission is done through 3phase systems. The characteristic parameters of the transmission line are. The shunt admittance per kilometer of the transmission line is 9 6 2 2 60 6. In order to achieve this a reflected wave is formed. A wave guiding structure is one that carries a signal. Transmission line parameter an electric transmission line has four parameters, namely resistance, inductance, capacitance and shunt conductance. Transmission lines basic principles norbert wiener. Power system generation, transmission and distribution. Assuming ex,t 2cos3x1015t 107x vm, calculate the wave velocity. Structure of power system parameters of single and three phase transmission lines with single and double circuits resistance, inductance and capacitance of solid, stranded and bundled conductors, symmetrical and unsymmetrical spacing and transposition application of self and mutual gmd. Reprinted with permission of penton media 160 chapter 4 transmission line parameters 9000 circuitmiles. Power absorbed by oneport the complex power absorbed by the oneport is given by p in 1 2 v1 i.
Hence, it is also called the distributed parameter of the transmission line. Assume the impedance of the line is 50 ohm, phase constant is 20 radm and the operating frequency is 700mhz. Kshetrimayum 52020 the circuit elements cannot be defined for the whole transmission line instead it. Ac transmission systems incorporating the power electronicbased to enhance controllability and increase power transfer capability. Transmission lines are not the main focus of this lecture or course and are extensively covered in ee117. The grid is the network of transmission lines that interconnect most large power plants on the north american continent. Equivalent transmission line of the homogeneous microstructures which have smooth pore walls in the transmission line, the surface impedance can be. Assume we have a transmission line in which air separated the two perfect conductors. The line parameters were determined by using the voltage and current measurements from either side of the transmission line. Lecture notes high speed communication circuits and. Transmission line conductor design comes of age by art and 400 kv, connecting more than 300 substations. The transmission line has mainly four parameters, resistance, inductance, capacitance and shunt conductance. Transmission line parameters obtained from text module 2. Transmission line parameterstransmission line parameters aim learn how to use atp to obtain series impedance parameters.
Kothari, does not currently have a detailed description and video lecture title. The average power can be obtained by taking one half of the real component of the complex power. Thus, a wave on the line faces the dilemma of obeying two difference ohms laws. Power system generation, transmission, and distribution is the most common subject and heart core subject to electrical engineers an electric power system is a network of electrical components used to supply, transmit and use electric power. Principles of rf and microwave measurements lecture notes and experiments. Kothari, centre for energy studies, iit delhi for more. The resistivity increases linearly with temperature over. The performance of transmission line depends on the parameters of the line.
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