In this paper, winding function method (WFM), applied to a faulted synchronous generator, is modified and is used for on-line diagnosis of mixed eccentricity fault. For the first time, the static and mixed eccentricities are modeled in synchronous generators. A modified winding function (MWF) method introduced here is more precise compared with previous methods. This MWF enables to compute the air gap magnetic permeance accurately. Here, two or three terms of the infinity permeance series has not been used, but a closed form equation is employed for permeance evaluation. This leads to a very precise computation of the inductances of the faulted machine. Self inductances of the stator and rotor, mutual inductance of two stator phases and the mutual inductance of rotor and stator are obtained. Meanwhile, it is shown that static, dynamic and mixed eccentricities lead to the increase of the amplitude and occurrence of the distortion in the aforementioned inductances. Since calculation of inductances is the most important step for fault diagnosis of the machine, the proposed method improves the on-line diagnosis of the fault. Meanwhile, the spectrum analysis of stator current, obtained from experimental results, is illustrated.
2. Faiz, J., B. M. Ebrahimi, B. Akin, and H. A. Toliyat, "Comprehensive eccentricity fault diagnosis in induction motors using finite element," Accepted in IEEE Trans. on Magnetics, 2008.
3. Faiz, J. and B. M. Ebrahimi, "Mixed fault diagnosis in three-phase squirrel-cage induction motor using analysis of air-gap magnetic field," Progress In Electromagnetics Research, Vol. 64, 239-255, 2006.
4. Faiz, J., B. M. Ebrahimi, and M. B. B. Sharifian, "Time stepping finite element analysis of rotor broken bars fault in a three-phase squirrel-cage induction motor," Progress In Electromagnetics Research, Vol. 68, 53-70, 2007.
5. Faiz, J. and B. M. Ebrahimi, "Static eccentricity fault diagnosis in an accelerating no-load three-phase saturated squirrel-cage induction motor," Progress In Electromagnetics Research B, Vol. 10, 35-54, 2008.
6. Zhu, J. and A. Qiu, "Inductance calculation of large salient-pole synchronous generators with air-gap eccentricity," IEEE Conference on Electromagnetic Field Computation, 264, 2006.
7. Melgoza, J. J. R., G. T. Heydt, A. Keyhani, B. L. Agrawal, and D.Selin, "An algebraic approach for identifying operating point dependent parameters of synchronous machines using orthogonal series expansions," IEEE Transaction on Energy Conversion, Vol. 16, No. 1, 92-98, Mar. 2001.
8. Foggia, A., J. E. Torlay, C. Corenwinder, A. Audoli, and J. Herigault, "Circulation current analysis in the parallel connected winding of synchronous generators under abnormal operating conditions," Electric Machines and Drives,International Conference IEMD '99, 634-636, 1999.
9. Toliyat, H. A. and N. A. Al-Nuaim, "Simulation and detection of dynamic air-gap eccentricity in salient-pole synchronous machines," IEEE Trans. Ind. Applicat., Vol. 35, 86-93, Feb. 1999.
10. Tu, X., L. A. Dessaint, M. El Kahel, and A. O. Barry, "A new model of synchronous machines internal faults based on winding distribution," IEEE Transaction on Industry Electronics, Vol. 53, No. 6, 1818-1828, Dec. 2006.
11. Al-Nuaim, N. A. and H. A. Toliyat, "A novel method for modeling dynamic air-gap eccentricity in synchronous machines based on modified winding function theory," IEEE Transaction on Energy Conversion, Vol. 13, No. 2, 156-162, June 1998.
12. Tabatabaei, I., J. Faiz, H. Lesani, and M. Nabavi, "Modeling and simulation of salient synchronous generators with dynamic eccentricity using modified winding fnction theory," IEEE Trans. on Magnetics, Vol. 40, No. 3, 1550-1555, May 2004.
13. Stoll, R. L. and A. Hennache, "Method of detecting and modeling presence of shorted turns in DC field winding of cylindrical rotor synchronous machines using two airgap search coil," IEE Proceeding, Vol. 135, No. 6, 281-294, 1988.
14. Hsu, J. S. and J. Stein, "Effect of eccentricities on shaft signals studied through winding less rotors," IEEE Transaction on Energy Conversion, Vol. 9, No. 3, 564-571, 1994.
15. Hsu, J. S. and J. Stein, "Shaft signal of salient-pole synchronous machines for eccentricity and shorted-field-coil detections," IEEE Transaction on Energy Conversion, Vol. 9, No. 3, 572-578, 1994.
16. Wamkeue, R., I. Kamwa, and M. Chacha, "Line-to-line short circuit based finite-element performance and parameter predictions of large hydro generators," IEEE Transaction on Energy Conversion, Vol. 18, No. 3, 370-378, 2003.
17. Faiz, J. and I. Tabatabaei, "Extension of winding function theory for non-uniform air-gap of electric machinery," IEEE Trans. on Magnetics, Vol. 38, 3654-3657, Nov. 2002.
18. Nickelson, L., S. Asmontas, R. Martavicius, and V. Engelson, "Singular integral method for the pulse-modulated microwave electric field computations in a 3D heart model," Progress In Electromagnetics Research, Vol. 86, 217-228, 2008.
19. Hemon, R., P. Pouliguen, H. He, J. Saillard, and J.-F.Damiens, "Computation of EM field scattered by an open-ended cavity and by a cavity under radome using the iterative physical optics," Progress In Electromagnetics Research, Vol. 80, 77-105, 2008.
20. Song, T.-X., Y.-H. Liu, and J.-M. Xiong, "Computations of electromagnetic fields radiated frp, cp, plex lightning channels," Progress In Electromagnetics Research, Vol. 73, 93-105, 2007.
21. Hussein, K. F. A., "Efficient near-field computation for radiation and scattering from conducting surfaces of arbitrary shape," Progress In Electromagnetics Research, Vol. 69, 267-285, 2007.
22. Lesselier, D. and B. Duchene, "Buried, 2-D penetrable objects illuminated by line sources: FFT-based iterative computations of the anomalous field," Progress In Electromagnetics Research, Vol. 05, 351-389, 1991.
23. Nesterenko, M. V., V. A. Katarich, Y. M. Penkin, and S. L. Berdnik, "Analytical methods in theory of slot-hole coupling of electrodynamic volumes," Progress In Electromagnetics Research, Vol. 70, 79-174, 2007.
24. Gaffour, L., "Analytical method for solving the one-dimensional wave equation with moving boundary," Progress In Electromagnetics Research, Vol. 20, 63-73, 1998.