US 5,180,923 A · Method and apparatus for downline load rejection sensing in a gas turbine control system

Abstract

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.

Claims23

Dependent claims

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, said apparatus comprising:

first reference means for generating a delta speed reference signal;
second reference means for generating a delta load reference signal;
first derivative means, connected to receive said speed signal, for determining the derivative of said speed signal, such derivative defining a speed derivative;
second derivative means, connected to receive said load signal, for determining the derivative of said load signal, such derivative defining a load derivative;
first comparator means, connected to receive said speed derivative and said delta speed reference signal, for comparing the speed derivative to said delta speed reference signal;
second comparator means, connected to receive said load derivative and said delta load reference signal, for comparing the load derivative to said delta load reference signal;
and
an indicator for indicating when both said first comparator means determines that said speed derivative exceeds said delta speed reference signal and said second comparator means determines that said load derivative exceeds said delta load reference signal.

5 more elements

An electric power plant for generating electric power and for providing such power to an electric power grid, said power plant comprising:

a combustion turbine, the combustion turbine being operative in response to the combustion of fuel in the turbine wherein the flow of fuel is regulated in response to a control signal;
a generator, connected to the power grid, so that electric power is produced when the turbine shaft turns;
a first reference member for generating a speed signal reflective of turbine speed;
a second reference member for generating a load signal reflective of the load on the generator;
a controller for generating a control signal in relation to the difference between the speed signal and a speed reference signal;
and
a third reference member for generating said speed reference signal, said third reference member comprising:
a first rate monitor, connected to receive said speed signal for monitoring the rate of change of said speed signal and for generating a speed indication signal when the rate of change of said speed signal exceeds predetermined speed change limits;
a second rate monitor, connected to receive said load signal for monitoring the rate of change of said load signal and for generating a load indication signal when the rate of change of said load signal exceeds predetermined load change limits;
and
a signal generator for generating said speed reference signal, wherein said speed reference signal is representative of synchronous speed when both of said first and second rate monitors are indicating that said speed change limits and said load change limits have been exceeded.

8 more elements

Dependencies are inferred from the claim text.

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

Life of this patent

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

Life of this patent

Abstract

Claims23