| 摘要 |
<p>An electrohydraulic control system for a steam turbine has steam valve actuators with analog valve position set points or reference values supplied by a main control loop with a digital computer. The digital computer performs complex calculations to obtain the valve position set points in accordance with operating parameters of the steam turbine and desired operational modes. A standby analog control loop furnishes a simple speed and load control function in the event of loss of digital signals. When in digital computer mode, the analog speed loop provides a safety backup function through a "dead band" which provides valve closing signals upon excessive speed. In the analog or standby mode, a load reference signal representing the most recent load set point is supplied to the analog control loop from a memory unit constantly updated by the digital computer.</p> |
