Method and apparatus for downline load rejection sensing in a control system for a gas turbine.

摘要

Method and apparatus for detecting load rejection in a combustion turbine, wherein a speed signal representative of the turbine speed and a load signal representative of the turbine load are provided. The invention includes referencing devices for generating a delta speed reference signal and a delta load reference signal, derivative devices for determining the derivative of the speed signal and the load signal, comparators for comparing the speed derivative to the delta speed reference signal and for comparing the load derivative to the delta load reference signal and an indicator for indicating the occurrence of two events, namely, the first comparator determines that the speed derivative exceeds the delta speed reference signal and the second comparator determines that the load derivative exceeds the delta load reference signal. In one embodiment a maximum turbine speed reference signal is provided and a third comparator compares the speed signal to the maximum turbine speed reference signal. In that embodiment the indicator provides a second indication on the occurrence of the first two events together with a third event, namely, a determination by the third comparator that the speed signal exceeds the maximum turbine speed signal. In a preferred embodiment of the invention, first and second rate monitors are provided for monitoring the rate of change of the speed signal and the load signal and for generating indications when the rate of change of the speed signal and the load signal exceeds predetermined rate of change limits.