Power System Protection in High Voltage Power System at 132kv.
ABSTRACT
In this thesis, a novel approach for the protection of transmission lines which utilizes only coefficient energy for both detection and classification is proposed.
The fault current signals generated by workspace on MATLAB simulation model have been analyzed using Daubechie-4 (d4) mother wavelet at 7th level decomposition with the help of Wavelet Toolbox embedded in MATLAB.
A case study of 132kV, 160km transmission line has been used to test the novel approach. The value of the coefficient energy of the current signals gives the indication of fault and no- fault conditions.
The energy of the three phase current signal (A,B,C) at 7th level decomposition were calculated as 0.1559×10-5, 0.1328 x10-5, 0.1737 x10-5 (for normal condition), 6.4200 x10-5, 1.7730 x10-5, 1.6660 x10-5 (for A-G fault), 667.1000 x10-5, 700.9000 x10-5, 0.7860 x10-5 (for AB-G fault), 677.8000×10-5, 689.9000 x10-5, 0.1740 x10-5(for A-B fault), 885.6000 x10-5, 898.3000 x10-5, 832.7000 x10-5(forABC fault).
Also, the coefficient energy ratios were calculated to help classify the faults. The total ratio of the coefficient energies of the three phases were found to be approximately 3.4819 (for normal condition), 5.9177 (for A-G fault), 1741.4580 (AB-G fault), 7861.3448 (for A-B fault), 3.1423 (for ABC fault).
Like the coefficient energy, the ratio was found to be increasing as the severity of the fault increases, except for L-L-L fault. Hence, both coefficient energy and ratio were employed in fault classification.
With the approach presented in this work, ten classes of fault (A-G, B-G, C-G, A-B, B-C, A-C, AB-G, BC-G, AC-G & ABC) could be correctly identified and classified within fault duration of 0.085 seconds. The results therefore, demonstrate the proposed approach to be fast and reliable.
INTRODUCTION
Electricity is a basic necessity of life in that social and economic development of any country is highly dependent on the availability of power supply.
Without adequate supply of power, businesses will not be full, companies will not produce, unemployment will set in and ultimately the standard of living will dwindle.
If everyone has to own generating unit, environment will not be conducive. But not even all homes can afford private generating unit. The most economical is to pull power from the national power system.
Power system is a very robust system, probably the largest and most complex industry in the world. It is comprised of generation, transmission and distribution.
These parts of the power systems are interconnected and the failure of any might affect the performance of the other. An important objective of all the power systems is to maintain a very high level of continuity of service, and when abnormal conditions occur, to minimize the outage times.
It is practically impossible to avoid consequences of natural events, physical accidents, equipment failure or disoperation which results in the loss of power and voltage dips on the power system.
Electrical Supply is a big and discrete investment that shows significant economies of size and takes time to build. Therefore, electrical outages are expensive.
Short term outages can destroy production and leisure while long term can be a serious impediment to economic growth and development. Several approaches are employed to guard the power systems against failure and to protect the components of power system in the event of faults.
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StudentsandScholarship Team.
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