| 摘要 |
<p>PURPOSE:To enable returning to a stable operating side by forcibly causing the number of revolutions of a water wheel to lower, when the operating point of said water wheel approaches the unstable operating range. CONSTITUTION:A secondary excitation controller 3 controls an AC excitation current supplied to the secondary side winding 1b of an induction machine 1 according to the deviation between an effective power P and a generating output command P0. Also, the opening of a guide vane 11 is controlled by a proper guide vane opening command Ya and a proper rotational speed command Na according to the generating output command P0 and a waterlevel signal H. Also, a speed corrector 30 divides the actual number of revolutions N by the square root of an effective head He to obtain the number of revolutions N1 per unit head and a reference speed deriver part 31 obtains a critical speed N1p for moving to an unstable range according to the opening of a guide valve. Further, a signal-correcting circuit 25 adds a correction signal P1 to the generating output command P0 in case of N1>N1p.</p> |
