| 摘要 |
PURPOSE:To stably maintain the system frequency, by operating a turbine bleed steam stop valve in a closing direction to increase a steam quantity passing a turbine when the frequency of a power generating system is rapidly reduced to a value lower than a frequency set value. CONSTITUTION:In normal operation, a turbine bleed steam stop valve is fully open to feed a bleed steam to each heater and increase a supply water temperature. When a system frequency is rapidly reduced under the condition, and a frequency value detected by a frequency detector 18 becomes lower than a frequency set value set by a frequency setting device 19, a monitor switch 20 is turned on. At this time, when a bleed steam stop valve control CS is set in an 'AUTO' position, a predetermined logic condition is satisfied by the combination of a NOT circuit NOT, AND circuit AND and OR circuit OR, thus outputting a closing command B to the bleed steam top valve. As a result, the turbine bleed steam is allocated to a main steam directly contributing to the power generation, thereby increasing a main steam quantity.
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