System for operating a steam turbine with bumpless digital megawatt and impulse pressure control loop switching

摘要

A steam turbine is provided with inlet throttle and governor valves which are positioned by an electrohydraulic control. A digital computer includes a speed control and a load control which respond to turbine speed and load signals and an electrical load signal to generate position control setpoints for the valves. A load reference is generated from an input load demand, and the reference is modified by a speed correction and selectively acted upon by a megawatt control and an impulse pressure control in the generation of the valve position setpoints. On the insertion of the megawatt control or the impulse pressure control into service, or on its removal from service, the computer instantly resets control parameters as required to provide for bumpless control loop switching.