Nonlinear Excitation Control of Two Sets of Adjustable Speed Generators/Motors at Rotary Type Frequency Converter Station for Performance Improvement of Power System Dynamics

There are 50Hz and 60Hz power systems in Japan, which are interconnected by power electronics based static type frequency converter station. Frequency converter can be realized by using Adjustable Speed Generators/Motors (ASGMs), which are excited by AC voltage, and so-called rotary type frequency converter. The rotary type frequency converter can also function as a power system stabilizer by effectively utilizing rotational energy stored in rotors. Nonlinear excitation control for the rotary type frequency converter is proposed to enhance performance of the rotational energy utilization and to improve stability of power system. The control performance is examined for a power system model by digital dynamic simulation. It is made clear that the proposed nonlinear excitation control is effective even though local information of the rotary type frequency converter is just used and that it has robustness against various load flow conditions.