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Numerical simulations of detailed time-dependent behavior are performed on a simulation model in which a coupled system of nonequilibrium disk MHD generator and line-commutated inverter is connected to an infinite bus through the transmission line, showing that continuous operation of the system is usually possible even when a power line fault occurs near the system. Then, time-dependent swing simulations are carried out on another simulation model in which the MHD/inverter system and a synchronous generator are connected in parallel to an infinite bus through the common transmission line, revealing that the rotor angle swing of the synchronous generator caused by the power line fault can be effectively suppressed by the fast output power control of the MHD/inverter system. © 1999 Scripta Technica, Electr Eng Jpn, 127(3): 13–24, 1999 [ABSTRACT FROM AUTHOR]

Two-dimensional stability analyses for open-cycle supersonic disk MHD generators are carried out which take into account electrical boundary conditions. A method of r-θ two-dimensional linear stability analysis for supersonic disk MHD generators is proposed which examines the time growth rate of perturbations. The growth rate is determined by the characteristic equation which is derived from the electrical boundary conditions. Whether the perturbations grow or decay is judged diagrammatically in a way similar to the Nyquist method. A coal-fired outflow supersonic disk MHD generator of commercial scale is analyzed under several types of boundary conditions. The stability is much affected by the electrical boundary conditions and also by the azimuthal wavenumber of disturbances. Two-dimensional analysis has revealed an azimuthally nonuniform instability in one of the load sections of the generator, where no instability is found in the one-dimensional analysis. The analysis also shows that the instability can be suppressed by subdividing the load section with control electrodes. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(4): 23–30, 1997 [ABSTRACT FROM AUTHOR]

Design and stability analyses of MHD disk-type generators are carried out, which are applied for coal-fired electrical power generation system with CO2 recovery. Channels designed with subsonic flow show rather poor performance compared with supersonic flow channels. Inflow channels show better performance than outflow channels. The inflow channel gives enthalpy extraction ratios of 20.21% and 21.12% for thermal inputs of 1100 MW and 2000 MW, respectively, while the outflow channel operated with supersonic flow yields enthalpy extraction ratios of 17.92% and 18.12% when the magnetic flux density is 8 T. The open-cycle disk channels tend to become unstable at the exit region. It seems possible to stabilize the disk channels when operated with 8 T but seems difficult to stabilize them when operated with 10 T. © 1997 Scripta Technica, Inc. Electr Eng Jpn 119(1): 9–16, 1997 [ABSTRACT FROM AUTHOR]

Stability of large-scale coal-fired MHD channels is studied by (1) linearized stability analysis, and (2) time-dependent 1-D analysis. The channel length is 15 m with 600 electrode pairs, and the output power ranges from 220.6 MW through 258.7 MW. Linearized stability analyses show that the Faraday channels operated with fixed loading resistance are stable, whereas the two waves of u and u - a (u, a: gas and sound velocity) become unstable in the Faraday channel with fixed loading factor. Two waves of u and u - a are unstable in the diagonal channel with fixed loading current and the u + a wave becomes unstable in the diagonal channel with fixed electrode current. Time-dependent one-dimensional analyses indicate that the Faraday channels with fixed load resistance are smooth without growth of fluctuation. The diagonal channels with fixed electrode current are smooth with no fluctuation, though the linear theory indicates that the u + a wave is unstable. The diagonal channel with fixed load current suffers large disturbance along the latter half of the channel, being consistent with the linearized analysis which indicates that the u - a and u waves are unstable. [ABSTRACT FROM AUTHOR]

This paper presents the results of the analysis of three-dimensional mutual interaction between electromagnetic field and fluid of the subsonic Faraday-type MHD generator. [ABSTRACT FROM AUTHOR]

The article discusses the operational characteristics of a power consolidation circuit for Faraday-type magnetohydrodynamic generator. The fundamental characteristics of Christmas tree type and Master/Slave type consolidation circuits are discussed, as well as the electrical nonuniformities caused by slag polarization. A schematic diagram of Christmas tree type power consolidation circuit with electrodes is presented.

The authors propose a new power consolidation-inversion-control system for the Faraday MHD generator using the voltage source PWM inverters. The dc output power for each electrodes pair of the MHD generator is at first inverted into three-phase ac power by a voltage source PWM inverter, and then the ac powers are consolidated by transformers. The proposed system does not need such expensive equipment as an ac filter or phase modifier and can independently and simultaneously control the active and reactive powers provided to the electric power system. Numerical simulations of the whole system, including the Faraday MHD generator, the proposed system can stably and steadily transit and control the electric power from the MHD generator to the electric power system. It is also confirmed that the proposed system can be independently and simultaneously control the active and reactive powers and can be used as a fast power controller. [ABSTRACT FROM AUTHOR]