Thats why 10 years ago digital designers didnt use transmission lines. Lei wu department of electrical and computer engineering. Kshetrimayum 52020 the circuit elements cannot be defined for the whole transmission line instead it. The power transmission line is one of the major components of an electric power system. An example of an electric power system is the network that supplies a regions homes and industry with powerfor sizable regions, this power. The grid is the network of transmission lines that interconnect most large power plants on the north american continent. Each line element has its own value, and it is not possible to concentrate or lumped them at discrete points on the line. 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. Transmission line conductor design comes of age by art and 400 kv, connecting more than 300 substations. 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 line design information in these notes, i would like to provide you with some background information on ac transmission lines. Thus, a wave on the line faces the dilemma of obeying two difference ohms laws. Calculate the line inductancemeter and capacitance meter.
The three physical embodiments that are of interest are the twowire transmission line, the coaxial transmission and. Since our electrical components are defined in unit length, the total values can be found by multiplying the unit length value by dx. The line parameters were determined by using the voltage and current measurements from either side of the transmission line. The term line parameters refer to the inherent series resistance and inductance that is found on transmission lines. 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. Coupling between transmission linescoupling between transmission lines now consider a zerosequence component i 02.
Kothari, centre for energy studies, iit delhi for more. Generalized reflection coefficient, smith chart, passives. Assuming ex,t 2cos3x1015t 107x vm, calculate the wave velocity. Reprinted with permission of penton media 160 chapter 4 transmission line parameters 9000 circuitmiles. The design of a transmission line depends on four electrical parameters. Pdf two port networks lecture for students introduction. Niknejads book or pozar, gonzalez, collin, etc ee142fall 2010 10 infinite ladder. Transmission line parameters obtained from text module 2. These parameters are uniformly distributed along the line. Lecture notes on power system engineering ii vssut.
In order to achieve this a reflected wave is formed. The characteristic parameters of the transmission line are. Assume we have a transmission line in which air separated the two perfect conductors. Transmission lines are used in power distribution at low frequencies, and in communications at high frequencies. Hence, it is also called the distributed parameter of the transmission line. Its major function is to transport electric energy, with minimal losses, from the power sources to the load centers, usually separated by long distances. Ac transmission line impedance parameters ac transmission is done through 3phase systems. Lecture notes high speed communication circuits and.
Transmission lines are not the main focus of this lecture or course and are extensively covered in ee117. 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. A wider conductor gives lower impedance as would be expected. A transmission line may have at its end an impedance, z, which is not equal to the characteristic impedance of the line 2.
Principles of rf and microwave measurements lecture notes and experiments. 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. A transmission line consists of two or more parallel conductors used to connect a source to a load. Power loss due to corona, practical importance of corona, use of bundled conductors in e. Transmission line parameterstransmission line parameters aim learn how to use atp to obtain series impedance parameters. Assuming ex,t 2cos3x1015t 10 7x vm, calculate the wave velocity. Equivalent transmission line of the homogeneous microstructures which have smooth pore walls in the transmission line, the surface impedance can be. Transmission line parameter an electric transmission line has four parameters, namely resistance, inductance, capacitance and shunt conductance. Solution of the differential equations describes how signals propagate, and leads to the extraction of a.
The electrical power is transmitted over a transmission line with a speed of light that is 3x10. 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. The shunt admittance per kilometer of the transmission line is 9 6 2 2 60 6. An electric transmission line has four parameters, namely resistance. Ee261 lecture notes electronic montana state university. We will have a brief introduction to help us understand some of the other concepts smith chart and sparameters. Lei wu department of electrical and computer engineering ee 333 power systems engineering.
A wave guiding structure is one that carries a signal. Hon tat hui transmission lines basic theories nusece ee2011 28 example 1 a 100. The resistivity increases linearly with temperature over. Example problem a 220kv, 150 mva, 60hz, threephase transmission line is 140 km long. In overhead transmission lines, the conductors are suspended from a pole.
The theory of distributed circuits transmission lines bridges circuit theory. 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. We will see that these four parameters are calculated from 1 the line. These four parameters are uniformly distributed along the whole line. Twoport equivalent circuit using impedance parameters. Lecture description this video lecture, part of the series power system generation by prof. 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. Power system generation, transmission and distribution. Lecture series on power system generation, transmission and distribution by prof. The transmission line has mainly four parameters, resistance, inductance, capacitance and shunt conductance. The average power can be obtained by taking one half of the real component of the complex power. Power absorbed by oneport the complex power absorbed by the oneport is given by p in 1 2 v1 i.
500 1482 481 334 1375 967 50 1058 284 1124 517 488 1364 1509 1000 102 797 66 590 405 385 305 755 22 1278 185 317 928 656 1091 568 468 190 503 1171