Yogeshwarsing CALLEECHARAN, Jan-olov AİDANPÄÄ, John R. BRAUER

No-load electromagnetic simulations of a hydropower generator considering the effect of rotor whirling

Electromagnetic (EM) analysis of hydropower generators iscommon practice but there is little emphasis on studying the effect of rotorwhirling in the analysis. This paper explores the effect on electromagneticanalysis as the rotor is allowed to whirl both in forward and inbackward directions under no-load conditions. As a hydropower generatorrotor shaft can experience whirling when under eccentric operation,the objective is to examine how whirling can affect the unbalancedmagnetic pull (UMP), flux densities, damper currents, and ohmic lossesin a synchronous hydropower generator. These results are obtained ina commercial FEM-based EM field modelling software package thatallows various degrees of freedom in motion types and multiple motioncomponents to be set. It is seen that backward whirling tends to inducehigher eddy currents than forward whirling does.

Keywords:

eccentricity, electromagnetic simulations hydropower rotor, no-load, whirl,

PDF

___

[1] M. Walker. Specification and Design of Dynamo-Electric Machinery. Longmans’ Electrical Engineering Series, 1915. [2] E. Rosenberg. Magnetic pull in electrical machines. Transactions of the American Institute of Electrical Engineers, 37(2):1425–1469, 1918. [3] I. Ozelgin. Analysis of magnetic flux density for airgap eccentricity and bearing faults. International Journal of Systems Applications, Engineering & Development, 4(2):162–169, 2008. [4] D. de Canha, W.A. Cronje, A.S. Meyer, and S.J. Hoffe. Methods for diagnosing static eccentricity in a synchronous 2 pole generator. In Power Tech, IEEE, Lausanne, pages 2162–2167, July 2007. [5] I. Tabatabaei, J. Faiz, H. Lesani, and M.T. Nabavi-Razavi. Modeling and simulation of a salient-pole synchronous generator with dynamic eccentricity using modified winding function theory. IEEE Transactions on Magnetics, 40(3):1550–1555, May 2004. [6] G. Joksimovic and C. Bruzzese. Static eccentricity detection in synchronous generators by field current and stator voltage signature analysis—Part I: Theory. In Electrical Machines (ICEM), XIX International Conference. 6–8 September, Rome, Italy, pages 1–6, 2010. [7] B.A.T. Iamamura, Y. Le Menach, A. Tounzi, N. Sadowski, and E. Guillot. Study of static and dynamic eccentricities of a synchronous generator using 3-D FEM. IEEE Transactions on Magnetics, 46(8):3516–3519, August 2010. [8] J. Faiz, M. Babaei, J. Nazarzadeh, B.M. Ebrahimi, and S. Amini. Timestepping finite-element analysis of dynamic eccentricity fault in a threephase salient pole synchronous generator. Progress in Electromagnetics Research B, 20:263–284, 2010. [9] T.P. Holopainen, A. Tenhunen, E. Lantto, and A. Arkkio. Unbalanced magnetic pull induced by arbitrary eccentric motion of cage rotor in transient operation. Part 1: Analytical model. Electrical Engineering, 88(1):13–24, April 2005. [10] T.P. Holopainen, A. Tenhunen, E. Lantto, and A. Arkkio. Unbalanced magnetic pull induced by arbitrary eccentric motion of cage rotor in transient operation. Part 2: Verification and numerical parameter estimation. Electrical Engineering, 88(1):25–34, March 2005. [11] N.L.P. Lundström and J.-O. Aidanpää. Whirling frequencies and amplitudes due to deviations of generator shape. International Journal of Non-Linear Mechanics, 43(9):933–940, November 2008. [12] Y. Calleecharan and J.-O. Aidanpää. Dynamics of an hydropower generator subjected to unbalanced magnetic pull. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 225(9):2076–2088, 2011. [13] Y. Calleecharan and J.-O. Aidanpää. Stability analysis of an hydropower generator subjected to unbalanced magnetic pull. IET Sci. Meas. Technol., 5(6):231–243, November 2011. [14] Division for Electricity, The Ångström Laboratory, Uppsala Universitet, Sweden. [15] H. Torkaman and E. Afjei. Magnetostatic field analysis regarding the effects of dynamic eccentricity in switched reluctance motor. Progress in Electromagnetics Research M, 8:163–180, 2009. [16] O. Biro. Computational Electromagnetics (CEM) Conference 2011— Review of Eddy current analysis. [online]. http://tv.theiet.org/technology/electronics/10890.cfm. [17] D. Marcsa and M. Kuczmann. Finite element analysis of single-phase induction motors. COMSOL Conference, Budapest, Hungary November 24, pp. 1–6, 2008. [18] M.V.K. Chari and P. Silvester. Analysis of turboalternator magnetic fields by finite elements. IEEE Transactions on Power Apparatus and Systems, PAS-90(2):454–464, March 1971. [19] J.R. Brauer. Magnetic Actuators and Sensors. Wiley-IEEE Press, 1st edition, February 2006. [20] MagNet, Infolytica Corporation, Montréal, Québec, Canada, 2011, Version 7.1.3. [21] W.A. Gardner. Statistical Spectral Analysis: A Non-Probabilistic Theory. Prentice Hall, January 1988. [22] F. Harris. On the use of windows for harmonic analysis with the discrete Fourier transform. In Proc. of the IEEE, volume 66, pages 51–83, 1978. [23] MATLAB, The MathWorks Inc., Natick, Massachusetts, USA, 2012, Version 7.14.0.739 (R2012a). [24] E.W. Kimbark. Power System Stability Volume III: Synchronous Machines, IEEE Press Series on Power Engineering. Piscataway, NJ (Wiley IEEE Press, New York), February 1995.