Rotor Dynamics Modeling for Compressor and Generator of the Energy Gas Turbine Unit with Active Magnetic Bearings in Operating Modes

The paper discusses the problems associated with adequate modeling of dynamic processes in an energy gas turbine unit with active magnetic bearings (AMBs) as rotor supports. This unit is a part of the gas turbine cogeneration plant (GT CP). The subject of the research is dynamics of turbine and generator rotors. The problem of modeling the phenomena of rotor dynamics at operating modes is solved with full consideration of controlled electromagnetic processes in circuits of active magnetic bearings. Their analysis is performed using the contour flux method utilizing detailed AMB equivalent circuit substitution schemes. They take into account almost all significant elements of the magnetic circuit (air gaps, sections of magnetic cores, grooves with windings, coils and other parts). Mathematical description of rotor dynamics of this mechatronic system is performed using the Lagrange-Maxwell equations. Simulation computational studies are based on integrating the resulting nonlinear system of differential equations for generalized coordinates and flux linkages of electric circuits of AMB coils. It is performed using the high-order Runge-Kutta numerical procedure. The simulation results include Campbell diagrams and amplitude-frequency characteristics of rotating rotors. Validation of the proposed approach and simulation tools for dynamic phenomena modeling in the considered rotor system is carried out by comparison with data known from open sources. The calculation results prove possibility of numerical simulation of rotor dynamics of this energy machine class with complex structure and control systems of supports and indicate advantages of the proposed approach.