Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – For fault location
Reexamination Certificate
1998-10-16
2004-10-26
Metjahic, Safet (Department: 2171)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
For fault location
Reexamination Certificate
active
06809523
ABSTRACT:
The present invention is directed to detection of partial discharge events in power systems such as cables, motors and transformers, and more particularly to a method and apparatus for detecting partial discharge events on-line while the power system is in operation.
BACKGROUND OF THE INVENTION
Partial discharge events in high-voltage power systems, such as high voltage power distribution cables, motors and transformers, are high-frequency discharges that take place in small portions of the system insulation. These discharges may have a duration on the order of ten to fifteen nanoseconds, and usually occur at a peak of the a.c. power cycle when electrical stress is highest within the insulation. Partial discharge events generate high frequency electromagnetic pulses that travel along the power systems.
High voltage equipment for use in electrical power systems is conventionally tested off-line for partial discharge activity that may indicate insulation defects and possible insulation failure. These conventional techniques typically involve coupling a capacitor in parallel with the equipment under test and measuring the discharge signals across an external impedance such as a resonant circuit. The resonant circuit expands the discharge current pulses in the time domain so that the pulses are easier to detect and measure. Both amplitude and phase of each partial discharge pulse may be recorded and analyzed relative to the test voltage. Apparatus of this character is not well suited for detection and analysis of partial discharge events in power systems while the systems are on-line.
It is therefore a general object of the present invention to provide a method and apparatus for detection and analysis of partial discharge events in an a.c. power system that are adapted for use on-line while the system is in operation, and that may be readily implemented for determining type and/or location of the partial discharges as they occur.
REFERENCES:
patent: 4949001 (1990-08-01), Campbell
patent: 5214595 (1993-05-01), Ozawa et al.
patent: 5475312 (1995-12-01), Sedding et al.
patent: 5933012 (1999-08-01), Bengtsson
patent: 5982181 (1999-11-01), Rokunohe et al.
N.H. Ahmed and N.N. Srinivas, “On-Line Patent Discharge Detection in Cables,” IEEE Transactions, vol. 5, No. 2, Apr. 1998, pp. 181-188.
N.H. Ahmed and N.N. Srinivas, “On-Line Patent Discharge Detection in Transformer”.
N.H. Ahmed and N.N. Srinivas, “On-Line Partial Discharge Detection in Cables,” IEEE Annual Report, Oct. 19, 1997, pp. 215-217.
P. VonGlahn and R.J. Van Brunt, “Continuous Recording and Stochastic Analysis of PD,” IEEE Trans. on Dielectric and Electrical Insulation, vol. 2, No. 4, pp. 590-601, 1995.
G. C. Stone, “The Use of Partial Discharge Measurements to Assess the Condition of Rotating Machine Insulation,” IEEE Electrical Insulation Magazine, vol. 12, No. 4, pp. 23-27, 1996.
E. Gulski, “Computer-aided Measurement of Partial Discharges in HV Equipment,” IEEE Trans. on Electrical Insulation, vol. 28, No. 6, pp. 969-983, 1993.
G. C. Stone, T.E. Goodeve, H.G. Sedding and W. McDermid, “Usual PD Pulse Phase Distributions in Operating Rotating Machines,” IEEE Trans. on Dielectric and Electrical Insulation, vol. 2, No. 4, pp. 567-577, 1995.
J. Fuhr. M. Haessing, P. Boss, D. Tschudi and R.A. King, “Detection and Location of Internal Defects in the Insulation of Power Transformers,” IEEE Trans. on Electrical Insulation, vol. 28, No. 6, pp. 1057-1067, 1993.
C.G. Henningsen, K. Polster, B.A. Fruth and D.W. Gross, Experience with an On-Line Monitoring System for 400 kV XLPE Cables, IEEE T & D Conference, Los Angeles, 1996.
E. Pultrum and T. Aabo, “Diagnostic Testing of Cable System,” Pennsylvania Electric Assocation T & D Committee Meeting, Sep. 1996.
N. De Kock, B. Coric and R. Pietsch, “UHF PD Detection in Gas-Insulated Switchgear-Suitability and Sensitivity of the UHF Method in Comparison with the IEC 270 Method,” IEEE Electrical Insulation Magazine, vol. 12, No. 6, pp. 20-25, 1996.
A.G. Sellars S.J. MacGregor and O. Farish, “Calibrating the UHF Technique of Partial Discharge Detection Using a PD Simulator,” IEEE Trans. on Dielectric and Electrical Insulation, vol. 2, No. 1 pp. 46-53, 1995.
A.G. Sellars, O. Farish B.F. Hampton and L.S. Pritchard, “Using the UHF Technique to Investigate PD Producted by Defects in Solid Insulation,” IEEE Trans. on Dielectric and Electrical Insulation, vol. 2, No. 3 pp. 448-459, 1995.
J.E. Pearson B.F. Hampton and A.G. Sellars, “A Continuous UHF Monitor for Gas Insulated Substation,” IEEE Trans. on Electrical Insulation, vol. 26, No. 3, pp. 469-478, 1991.
Ahmed Nezar
Srinivas Nago
LeRoux Etienne P
Metjahic Safet
Reising Ethington Barnes Kisselle P.C.
The Detroit Edison Company
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