ANALYSIS OF HARMONIC COMPOSITION OF THE ALTERNATING MAGNETIC FIELD ASSOCIATED WITH THE ROTATING ROTOR OF TURBOGENERATOR IN THE NO-LOAD AND SHORT-CIRCUITS MODES

Abstract

The method of calculation of the magnetic field alternating component at the surface of the rotating rotor of turbo generator is presented. It is based on multiposition of the numerical calculations of the magnetic field with the rotor turns and changes of currents in the stator winding. Discrete time functions of the alternating component of the magnetic induction are selected in points of the surface . The harmonic analysis is conducted for them. The developed method is universal in terms of excitation modes, designs and the magnetic core saturation. The theory is confirmed by computational researches in the no-load and short circuit modes of large turbo generator. In it, the alternating component of the magnetic induction on the rotor surface in the short-circuit mode is much greater than in the no-load mode. Values and harmonic composition of the alternating component of the magnetic induction differ substantially at different points of the rotor surface. Harmonics are ponderable in the range from the level determined by the phase structure of stator winding to the level determined by the tooth structure of its core. The results obtained are qualitatively fit into the classical notion of oscillatory processes of the magnetic field on the rotor surface, but now the value and harmonic composition of the alternating component of the magnetic induction receive adequate numerical filling. The result of work can be used for designing of a turbogenerators and other synchronous machines.