Simulation Study Of Operating Performance For Asynchronized Turbogenerators With The Faults In The Excitation System

An asynchronized turbogenerator (ASTG) is composed of a machine with two identical reversible thyristor systems on the rotor as an exciter and dual passage exciting controller. The ASTG has a rotor of a new design with two field windings shifted at a mechanical angle of ninety degrees. Excitation system of asynchronized generators consists of a reverse thyristor converter (RTC) connected through an adjusted 3-winding transformer (TC) to the stator output. An asynchronized turbogenerator is different from a conventional synchronous turbogenerator on the rotor. It disposes symmetrical 2-phase symmetrical windings on the rotor and can meet any necessary orientation of exciting MMF relatively to the rotor body by means of adjustable currents in the rotor windings. In this dissertation, the operation principle of ASTG and the control strategy of the excitation system are analyzed as well as the simulation models of the generator and excitation controller are established based on the Saber simulator. The control strategy of an asynchronized turbogenerator in this dissertation describes the mathematical model as well as studies its regulative characteristics of active and reactive powers independently. Considered the speed governor and excitation regulator, this dissertation simulates the process of ASTG with partial faults in excitation system and the excitation doesn't work entirely.Dual-passage excitation model is presented based on the analysis of ASTG with partial faults in the excitation system. Considering the simulation models for ASTG including the model of reverse thyristors in the excitation system are established by Saber software in this dissertation. During the steady state operation of ASTG, simulation results of the dynamical process when the working thyristors on any excitation circuits will be damaged suddenly, the regulative process of the active power and the reactive power in terms of required power system will be carried out. These simulation results show that ASTG can return to the original steady state operation when any working thyristors will be damaged suddenly and this dynamical process will be stable as well as the regulative performances of the active power and reactive power for ASTG with partial faults and the excitation system will appear in good working order.Using the two-axes equations of Asynchronized turbogenerators in this dissertation emphasizes also the control strategy and simulates the process of an ASTG with faults of the d(q)axis and d,q axes in the excitation system. The simulation results show that, the loss of excitation at both windings and on one rotor winding, the asynchronized turbogenerators can be automatically driven into an asynchronous mode and single axis excitation operation mode without a power unit tripping by means of some operations. The characteristics for ASTG with faults in the excitation system will appear in good working order.Simulation results of steady state operation and transient process of an asynchronized turbogenerator demonstrate that an asynchronized turbogenerator has a lot of advantages over traditional synchronous generator for power system.