| 摘要 |
PURPOSE:To realize controlling sudden decrease and increase of steam flow so as to prevent step out and the like in case of an accident in electric power system by providing an adjusting valve openable at high speed and an adjusting valve closable at high speed in a row in a steam pipe of a steam turbine. CONSTITUTION:Two steam adjusting valves 1, 2 are provided in a row on a steam pipe 3 in steam supply system of a steam turbine 2. The adjusting valve 1 can let a rated flow of a plant run when it is opened to its full width, and is capable of high speed motion in off direction, while the adjusting valve 2 can let about 70% of the rated flow run when it is opened to its full width, and is capable of high speed motion in on direction. During normal operation, steam flows of the adjusting valves 2 and 1 are controlled in the ratio of about seven to three. At this time, if a grounding accident and the like of a transmission line occurs, the adjusting valve 2 is completely closed with rapidity. Since the adjusting valve 1 is fully opened with rapidity right after the abovementioned closure, the steam flow is quickly decreased, then quickly recovered, and step out or the like of a generator can be prevented. |
