18-01-2010, 02:22 AM
A Seminar Report
On
FRACTIONAL FREQUENCY TRANSMISSION SYSTEM
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ABSTRACT
Present day Power System uses the frequency of 50Hz and facing some
Voltage and Power stability problems. In order to limit the problem a new method is
proposed. The Fractional Frequency Transmission System (FFTS) is a very promising
long-distance transmission approach, which uses lower frequency (50/3 Hz) to reduce
the electrical length of the ac power line, and thus, its transmission capacity can be
increased several fold. The proposed approach can multiply increase transmission
capacity and remarkably improve operating performance. The structure and
implementation scheme of the FFTS is discussed here along with the feasibility study
and experiment conducted on FFTS. The performance of FFTS against conventional
AC transmission system is compared here. The proposed method gives better result
when compared to the conventional method.
CHAPTER 1
INTRODUCTION
Increasing transmission distance and capacity is always the motivation to
advance power industry technologies. In the history of the ac transmission system,
increasing distance and capacity mainly depends on raising voltage level of
transmission lines. At present, the highest voltage level of the ac power transmission
line in operation is 750 kV. To further upgrade, the voltage level encounters
difficulties of material and environment issues. The high-voltage direct current
(HVDC) transmission that has no stability limit problem once became another
approach to increasing electricity transmission capacity. However, the current
converters at two ends of HVDC are very expensive. In addition, up to now, the
HVDC practices have been limited to the point-to-point transmission. It is still
difficult to operate a multiterminal HVDC system. From 1982 to 2003, the total
HVDC transmission capacity in the world was only 70 GW. The flexible ac
transmission system (FACTS) has been used to improve power system performance
and has become a very hot research field. The FACTS exploits power electronic
techniques to regulate the parameters of the ac transmission, which can raise
transmission capacity to some degree.
China is very rich in hydro-power resources. They are mostly concentrated in
the West China. But the large loads are mainly located in the East and the South coast
area where industry and agriculture are well developed. These conditions determine a
basic structure of electric transmission from the West to East. The distance of
transmission ranges from 1000 to 2500 km. The long distance transmission of
electricity becomes an obstacle to hydro power development in China. At present, the
DC transmission system is too expensive for China to widely use. The highest voltage
level of AC transmission in China is 550 kV. This voltage level does not satisfy
power transmission over 1000 km. It is said that at least 20 years are necessary to
develop the transmission of higher voltage class and to manufacture the respective
equipment.
In 1994, X. Wang proposed a novel electricity transmission approach, the
fractional frequency transmission system (FFTS), which provides an efficient
approach to solving the above problem. As it is well known, AC long distance
transmission is mainly subject to problems with respect to steady and transient
stability which are in turn restricted by its reactanceâ„¢s. The new transmission system
uses fractional frequency (i.e. 50/3 Hz in our study) to reduce the reactances of the
AC transmission system, hence can multiply increase transmission capacity and
remarkably improve its operating performances.
Submitted in partial fulfilment for the award of the Degree of
Master of Technology in Electrical Engineering
(Computer Controlled Industrial Power)
Submitted by
Nihas K
Roll No. M080394EE
M.Tech in Electrical Engineering
(Computer Controlled Industrial Power)
Department of Electrical Engineering
NATIONAL INSTITUTE OF TECHNOLOGY CALICUT
Calicut, Kerala - 673 601.
April 2009
REFERENCE
[1] X. Wang, The fractional frequency transmission system, in Proc. Inst.
Elect. Eng. Jap. Power Energy, Tokyo, Japan, Jul. 1994, pp. 53“58.
[2] X. Wang and X. Wang, Feasibility study of fractional frequency transmission
system, IEEE Trans. Power Syst., vol. 11, no. 2, pp. 962“967, May 1996.
[3] O. I. Elgerd, Electric Energy Systems Theory. New York: McGraw-Hill, 1985.
[4] P.P. Biringer, J.D. Lavers, Recent Advances in the Design of Large Magnetic
Frequency Changers, IEEE Trans. on Magnetics Vol. MAG-12, No. 6,
November 1976
[5] Wang Xifan, Experiment on Fractional Frequency Transmission System,
IEEE Trans. Power Syst., vol. 21, no. 1, February 2006
[6] V.K Mehta, Rohith Mehta, Principles of Power System, S Chand 2004
[7] B.L.Theraja, A.K. Theraja, A textbook of electrical technology, vol II, S
Chand, 2003
