Nonlinear excitation control for rotary type frequency converter using two sets of adjustable speed generators/motors

At present, there are 50 Hz and 60 Hz power systems in Japan, which are connected by power electronics-based frequency converter stations. A frequency converter can also be realized by using an adjustable speed motor (ASGM) whose structure is similar to induction machine, however; it is excited by AC voltage. The controller in this paper is designed for an excitation system of each set of ASGM in the frequency converter by using local information of ASGM, in order to regulate the voltage and control the active power. The control performance is examined for a model power system by digital dynamic simulation. It is made clear that this kind of controller is effective even though the controller uses just local information of ASGM. However, its performance depends on the capacity of the ASGM, the load flow conditions and the oscillatory mode of the target.