Method for operating steam turbine with transient elevated back pressure

摘要

A method and control system can implement a transient exhaust pressure protection logic to avoid a turbine exhaust vacuum trip due to a short duration turbine exhaust pressure transient that may be caused by a large reduction in turbine flow coupled with a transient increase in exhaust pressure, which specifically occurs during full load rejections. When full load rejection conditions are sensed by power load unbalance and confirmed by secondary indications, normal alarm settings and trip settings for turbine exhaust pressure are blocked for a delay period while transient operating limits are in place.