Advanced control system for power generation
AssigneeJohn P. McDonald
InventorsJohn Patrick McDonald, Harry G. Kwatny
Life of this patent
Estimating the term…
Abstract
Inplant sensors in the boiler and turbine units sense present values of a number of physical parameters designated process variables, and of certain control variables. Set points are developed, and deviations therefrom of the control and process variables are calculated. Utilizing a mathematical model, state variable deviations are estimated and translated into corresponding physical parameter estimates, which are used to evaluate model inaccuracy. State variable and model error estimates are translated into desired control deviations, which in turn are combined with fed forward values of the control variable set points. The combined control terms actuate controllers in the boiler and turbine units.
Claims17
In a system having a first plurality of physical parameters designated y, measurable by sensing means, and a second plurality of input control parameters designated u, alterable in said system by control means, said system being identified with a predetermined mathematical model of the form dx/dt= Ax+ Bu, y= Cx+ Du for translating said control parameters into a third plurality of state variables designated x which dynamically characterize the behavior of said system, and for translating said state variables and control parameters into the measurable physical parameters, said model being exercised in and by sequentially operating computer means, a method for controlling said system to meet specified output requirements comprising the steps of:
- (a) measuring, at said sensing means, the present values of said physical parameters;
- (b) developing a set of estimates of said state variables;
- (c) translating said estimates of said state variables into corresponding estimates of said physical parameters;
- and
- (d) controlling said system to meet said requirements, said controlling step including operating said computer means to perform the steps of
- (1) predicting error of said set of values of said estimates of said physical parameters resulting from inaccuracy in said methematical model;
- (2) developing, in response to said set of values of said estimates of said state variables, to predicted error from said predicting step, and to said present values of said physical parameters, a set of values for said input control parameters, and
- (3) coupling said set of values for said input control parameters to said control means in said system.
An integrated electrical power generation and control system comprising;
- (a) turbine means having a first plurality of physical characteristics and a second plurality of input factors;
- (b) boiler means for producing steam for said turbine means, said boiler means having a third plurality of physical characteristics and a fourth plurality of input factors;
- and
- (c) sensing means, in said turbine means and said boiler means, for detecting present values of said first and third pluralities of characteristics;
- (d) means including sequentially operating computer means for controlling said turbine means and said boiler means, CHARACTERIZED IN THAT said computer means is programmed to perform the steps of
- (1) measuring present values, from said sensing means, of said first and third pluralities of characteristics, said measured values being designated y,
- (2) developing, in accordance with a mathematical model of said boiler means and said turbine means, of the form dx/dt= Ax+ Bu, y= Cx+ Du, estimated changes in a plurality of state variables designated x which approximate specified requirements of said systems,
- (3) translating said estimated changes into corresponding estimated changes in the said first and third pluralities of characteristics;
- (4) predicting error in said estimated changes in said first and third pluralities resulting from inaccuracy in said mathematical model,
- (5) synthesizing, in response to said measuring, developing, and predicting steps, a set of control values for said second and fourth pluralities of input factors designated u;
- and
- (e) means for actuating operational changes in said turbine means and boiler means in accordance with control values produced by said computer means in said synthesizing step.
In an electrical generating station having a first plurality of measurable physical parameters, designated y and measurable by sensing means, said physical parameters being governed by a second plurality of input control parameters designated u and alterable in said system by control means, a method of controlling said system to meet a specified output demand comprising the steps of:
- (a) sensing present values of said physical parameters and said control parameters utilizing said sensing means;
- (b) providing a programmed sequentially operating computer means to perform the steps of
- (i) translating said specified demand into a set of reference values for said physical parameters and for said input control parameters,
- (ii) developing differentials between present values of said physical parameters and said input control parameters, and corresponding reference values from said translating step,
- (iii) adjusting physical parameter differentials to compensate for the amplitude of input control parameter differentials,
- (iv) developing from the input control parameter differentials and from the adjusted physical parameter differentials, in accordance with a predetermined mathematical model, dx/dt= Ax+ Bu, y= (X+ Du, corresponding differentials of a plurality of state variables designated x which characterize said system,
- (v) translating said differentials of a plurality of state variables into associated differentials in said physical parameters,
- (vi) estimating error in differentials of said physical parameters introduced in said last named translating step due to inaccuracy of said mathematical model;
- (vii) correcting said adjusted physical parameter differentials to account for said modelling error,
- (viii) establishing new values of said input control parameters in response to said reference values thereof, to said differentials of said plurality of state variables, and to corrected adjusted physical parameter differentials,
- (ix) coupling said new values to said control means;
- and
- (c) applying said new values of said input parameters to said system to realize corresponding change in said physical parameters.
Dependencies are inferred from the claim text.