A flywheel generator system composed of a doubly fed induction machine and an inverter feeding control current to the rotor coil of the machine has quick response in both effective and reactive power outputs. The application of such systems for the enhancement of power system transient stability has been widely investigated by simulations, where previously mostly phasor domain calculations have been performed. Targeting actual applications of the system, a more accurate and precise calculation method. i.e., in the time domain (instantaneous value-based), has been required.
Recently the Electro-Magnetic Transient Program (EMTP) has been significantly improved and, without special difficulty, time domain calculation of transient stability involving doubly fed machines, inverter(s), synchronous machine(s), and detailed actual system parameters has become realistic.
This paper describes EMTP calculations of transient stability enhancement phenomena by a doubly fed machine flywheel generator, together with items necessary for the application of EMTP to such calculations. Some results peculiar to time domain calculations are also presented.