Analytical studies on application of doubly-fed rotary frequency converter in power systems

In this paper, we propose new rotary equipment for interconnected operations of power systems. That is a doubly-fed rotary frequency converter, which consists of two machines that are directly connected each other with shaft and they are both doubly-fed machines, or a synchronous machine and a doubly-fed machine. Analytical models were newly developed in order to analyze and understand the dynamic behavior of the proposed doubly-fed rotary frequency converters. Basic control scheme for the converters is proposed. Results of studies on dynamic characteristics of the control systems applied in the converters are shown. Moreover, merits and demerits were discussed in comparison with static DC converter with thyristor valves from the practical point of view.