Behavior of He-Cs closed-cycle disk MHD generator connected to electric power system through line-commutated inverter

Abstract

The basic characteristics of He-Cs closed-cycle disk MHD generator connected to an electric power system through a line-commutated inverter are investigated in detail by carrying out time-dependent numerical simulations for the whole interconnecting system. The simulation model is assumed to consist of the closed-cycle disk MHD generator with 100 MW thermal input and 40 MW electrical output, the double-bridge line-commutated inverter, the a.c. filter, the phase modifier, the double-circuit transmission line and the infinite bus. It is made clear that the generator is stable, and its performance is excellent at the nominal operating condition. The active power can be controlled by using the firing angle as the manipulated variable. This active power control method is, however, considered to be not advisable because the ionization instability occurs when the firing angle is near 90°. The operation of the generation system should be stopped as quickly as possible in the case of a continuous inverter fault because this fault induces remarkable fluctuations of the gas dynamical quantity distributions in the generator. The continuous operation of the generation system is usually capable in the case of power line fault because the generator returns to its nominal operating condition after the fault is cleared. The operation should be stopped only in the unusual case of a continuous power line fault without clearance.