Combined cycle electric power plant having an improved digital/analog hybrid gas turbine control system

摘要

A digital computer system provides automatic control for a steam turbine and two gas turbines in a combined cycle electric power plant during startup and load modes of operation. The gas turbine automatic control system provides speed, load and blade path temperature control functions in developing an output fuel control signal for application to each gas turbine fuel valve control. An analog control for each gas turbine selectively provides startup and temperature and load control functions as a backup for the automatic gas turbine control, and further provides gas turbine overspeed, surge and other limit controls continuously. An operator panel functions with the analog and digital controls to provide an operator interface with the plant, and an interface circuit ties the digital and analog controls together for bumpless transfer between manual and automatic modes of operation. A sequencer is provided for each gas turbine and it provides gas turbine startup sequence control, gas turbine trip protection and other functions in both the automatic and the backup modes of operation. A gas turbine monitor develops temperature and vibration signals for the sequencer and the fuel controls.