| 摘要 |
PURPOSE:To adjust transmission power to a d.c. system by determining an accident at high speed at the time of accident of an a.c. system to adjust the phase lead angle beta of an ac/dc converter. CONSTITUTION:A lowering pattern obtained by converting an a.c. system voltage into a d.c. voltage at the time of the accident of an a.c. system is stored into a memory 14. The a.c. system voltages are respectively converted into direct currents by a circuit for converting into a direct current and quantized by an A/D converter 12 and the lowering pattern of a d.c. voltage value is obtained from the d.c. voltage value quantized by a micrcomputer 13, and the obtained lowering pattern is compared with the lowering pattern stored in the memory 14, and a gate pulse generating circuit 15 ignites a a thyristor 5 by a phase lead angle in accordance with the comparison result to adjust transmission power. Thereby, though the conventional Fourier operation of one waveform (17msec) takes much time, this calculation can be made using a part of waveform, so that the processing may be performed at high speed. |
