System for operating a steam turbine with bumpless digital megawatt and impulse pressure control loop switching
First Claim
1. A control system for a large electric power steam turbine having a plurality of turbine sections to which steam is supplied through at least one throttle valve and a plurality of governor valves, said control system comprising means for electrohydraulically controlling the position of the throttle and governor valves in response to setpoint signals and signals representative of the valve positions, means for generating signals representative of the turbine speed and the turbine impulse pressure, means for generating signals representing a valve setpoint for application to said electrohydraulic position controlling means to position the value for load control after synchronization in response to a load reference in a load control loop, means for normally generating a speed corrected load reference as a function of the speed signal and the load reference, means for generating an impulse pressure load reference as a function of the impulse pressure signal and a setpoint derived from the speed corrected load reference, means for connecting and disconnecting said inpulse pressure reference generating means in the load control loop, means for setting the load reference to a post-connection value or a post-disconnection value which enable the valve setpoint to have the same value just before and just after a connecting or disconnecting action by said connecting and disconnecting means, and means for setting the impulse pressure reference and the impulse pressure setpoint to respective values which enable the valve setpoint to have the same value just before and just after a connecting action by said connecting and disconnecting means.
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Abstract
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.
42 Citations
16 Claims
- 1. A control system for a large electric power steam turbine having a plurality of turbine sections to which steam is supplied through at least one throttle valve and a plurality of governor valves, said control system comprising means for electrohydraulically controlling the position of the throttle and governor valves in response to setpoint signals and signals representative of the valve positions, means for generating signals representative of the turbine speed and the turbine impulse pressure, means for generating signals representing a valve setpoint for application to said electrohydraulic position controlling means to position the value for load control after synchronization in response to a load reference in a load control loop, means for normally generating a speed corrected load reference as a function of the speed signal and the load reference, means for generating an impulse pressure load reference as a function of the impulse pressure signal and a setpoint derived from the speed corrected load reference, means for connecting and disconnecting said inpulse pressure reference generating means in the load control loop, means for setting the load reference to a post-connection value or a post-disconnection value which enable the valve setpoint to have the same value just before and just after a connecting or disconnecting action by said connecting and disconnecting means, and means for setting the impulse pressure reference and the impulse pressure setpoint to respective values which enable the valve setpoint to have the same value just before and just after a connecting action by said connecting and disconnecting means.
- 6. A control system for a large electric power steam turbine having a plurality of turbine sections to which steam is supplied through at least one throttle valve and a plurality of governor valves, said control system comprising means for electrohydraulically controlling the position of the throttle and governor valves in response to setpoint signals and signals representative of the valve positions, means for generating signals representative of the turbine speed and the turbine impulse pressure, in response to a load reference in a load control loop, means for normally generating a speed corrected load reference as a function of the speed signal and the load reference, means for generating a signal representative of generated electrical power, means for generating an electrical power corrected load reference as a function of the electrical power signal and the speed connected load reference, means for connecting and disconnecting said electrical power corrected reference generating means in the load control loops, means for setting the load reference to a post-connection value or a post-disconnection value which enable the valve setpoint to have the same value just before and after a connecting or disconnecting action by said connecting and disconnecting means, and means for setting the electrical power corrected reference and the electrical power reference to respective values which enable the valve setpoint to have the same value just before and just after a connecting action by said connecting and disconnecting means.
- 9. A system for operating a steam turbine in an electric power plant comprising an arrangement of throttle and governor valves for supplying steam to the turbine, a control system having means for electrohydraulically controlling the position of the throttle and governor valves in response to setpoint signals and signals representative of the valve positions, means for generating signals representative of the turbine speed and the turbine impulse pressure, means for generating signals representing a valve setpoint for application to said electrohydraulic position controlling means to position the value for load control after synchronization in response to a load reference in a load control loop, means for normally generating a speed corrected load reference as a function of the speed signal and the load reference, means for generating an impulse pressure load response reference as a function of the impulse pressure signal and a setpoint derived from the speed corrected load reference, means for connecting and disconnecting said impulse pressure reference generating means in the load control loop, means for setting the load reference to a post-disconnection valve or a post-disconnection value which enable the valve setpoint to have the same value just before and just after a connecting or disconnecting action by said connecting and disconnecting means, and means for setting the impulse pressure reference and the impulse pressure setpoint to respective values which enable the valve setpoint to have the same value just before and just after a connecting action by said connecting and disconnecting means.
- 14. A system for operating a steam turbine in an electric power plant comprising an arrangement of throttle and governor valves for supplying steam to the turbine, a control system having means for electrohydraulically controlling the position of the throttle and governor valves in response to setpoint signals and signals representative of the valve positions, means for generating signals representative of the turbine speed and the turbine impulse pressure, means for generating signals representing a valve setpoint for application to said electrohydraulic position controlling means to position the valves for load control after synchronization in response to a load reference in a load control loop, means for normally generating a speed corrected load reference as a function of the speed signal and the load reference, means for generating a signal representative of generated electrical power means for generating an electrical power corrected load reference as a function of the electrical power signal and the speed corrected load reference, means for connecting and disconnecting said electrical power corrected reference generating means in the load control loop, means for setting the load reference to a post-connection value or a post-disconnection value which enable the valve setpoint to have the same value just before and just after a connecting or disconnecting action by said connecting and disconnecting means.
Specification