The Babcock & Wilcox Company

Elsag International N.v.

Elsag International B.v.

Thomas J Scheib

John D Lane

William H Moss

Theodore N Matsko

Marion A Keyes, Iv

Azmi Kaya

Gregory Khrapunovich

Kenneth Alan Loparo

George S Whaley

Donald J Dziubakowski

Thomas D Russell

Joseph G Patella

Marc Buchner

Ken Loparo

John H Klatt

Peter K Lui

Kenneth Loparo

Robert S Rand

Douglas E Kyr

Lawrence Popiel

Robert R Walker, Deceased

David L Lane

Martin Gulaian

Marty Gulaian

Anti-windup and noise protection that can be used with any general digital controller. The anti-windup technique allows the implementation of noise filtering techniques to decrease or eliminate chatter of the control output at the limit. In a higher order controller that uses a feedforward signal, the anti-windup technique prevents an unexpected change in the control output when a step change occurs in the feedforward signal. The technique can be used to provide anti-windup protection in both single layer and multi-layer control schemes.

Windup and noise protection of digital controllers in a layered control

A distributed control system wherein status is propagated through the system along with the signal with which the status is associated. The function blocks of the system include rules for propagation of the status through the system. The system may also include function blocks for testing the propagated status to determine if the same is bad and function blocks to force the propagated status to have a certain status. The rules may be customized by the user, for example, to block status propagation through a function block.

Signal status propagation in a distributed control system

A method of estimating pH titration curves for use in the adaptive control of pH in a process, comprises gathering data points which each represent the ratio between a reagent added to the process and a flowrate to the process at a measured pH, storing the data points in a bin system according to pH, and using the stored data points to create a model of the titration curve for use in controlling the addition of reagent. Older points are replaced by newer points during the process to continuously update the model. The model was used to generate a gain schedule for operating a PI controller that is used in adding a reagent to the process.

Methodology for pH titration curve estimation for adaptive control

An identification technique that includes a closed loop parameter estimation algorithm for process gain, time constant and deadtime. The estimation algorithm uses time integrals of system variables responding to a step input. Proper selection of the integrals (control areas) results in a set of equations which are solvable for desired process parameters.

Parameter estimation technique for closed loop system

A self-tuning system and method for controlling a process based on a measured variable comprises modular parameter estimators, parameter converters and controllers which are used to control the process and receive input from the process. Self-tuning gain scheduling allows the calculated parameters to be updated by a second variable from the process. Regression analysis is used in conjunction with the conventional gain scheduling to more accurately refine the control action. A limiter is also used in conjunction with the regression analysis to avoid an overly high or low correction signal for the controller.

Apparatus and method using adaptive gain scheduling

A proportional plus integral plus differential (PID) controller containing an algorithm option is disclosed. The option allows the selection of a classical interacting type of controller or a non-interacting type of controller. The classical interacting type of controller is characterized by the property that tuning any one of the proportional, integral or derivative terms changes the effective value of the other terms. In contrast, the non-interacting type of controller is characterized by the property that tuning any one of the proportional, integral or derivative terms has no effect on the other terms.

Advanced proportional plus integral plus derivative controller

A system for controlling steam temperature in a boiler using a time delay feedback controller known as a Smith Predictor to provide control tuning of true boiler parameters which change with load.

Steam temperature control using a modified Smith Predictor

A self-tuning system and method for controlling a process based on a measured parameter comprises modular parameter estimators and parameter controllers which are used in conjunction with the process and which receive as an input the measured parameter. An internal model controller is used as one of the parameter converters and incorporates a feed forward index which is used for gain scheduling. Regression analysis is also used in conjunction with the conventional gain scheduling to more accurate refine the control action. A limiter is also used in conjunction with the regression analysis to avoid an overly high or overly low correction signal for the controller.

Apparatus and method using adaptive gain scheduling algorithm

A method and apparatus of obtaining a correction value for the deviation between an actual power usage and a desired target power usage during a time period, comprises dividing the time period into a plurality of time segments, measuring, after each time segment a fraction of time into each time period, and multiplying the fraction by the target power usage to obtain a value corresponding to the fraction of the total power usage during the cycle. Also after each time segment, the total amount of power which has actually been used is measured and a difference is taken between the total amount power used from the beginning of the period and the fraction of the target power usage from the beginning of the period. This value is then divided by the amount of time remaining in the cycle to obtain the correction value. The correction value can be processed and utilized to control an internal generator for the plant or to take other corrective action.

Tieline control

A method of identifying a parameter of a model for a rate of loss of boiler efficiency due to a sootblowing operation, in a boiler having a plurality of heat traps, comprises measuring a time since a last sootblowing operation in the heat trap in question, measuring an overall boiler efficiency at the beginning of sootblowing for the heat trap in question, measuring a change in efficiency due to the sootblowing operation and calculating the parameter using an equation. According to the equation, the ratio of efficiency change over overall boiler efficiency equals the time factor since the last sootblowing operation times the parameter minus a summation of factors for each of the other heat traps and their associated sootblowing operations. The technique is extendable to individual sootblowers within a heat trap by using fouling rate index rather than overall boiler efficiency.

Sootblowing system with identification of model parameters

A program timer control is disclosed for applying one of at least two functions to a parameter controller which is varied over the course of a full day. A day counter counts the passage of days and operates a switch to control the parameter controller according to the non-working day function when a weekend day occurs. A manually operable setting element is also provided when the following day is a holiday to select the non-working day function. All other days are assumed to be working days so that the switch is operated to apply the working day function to the parameter controller.

Program timer control

A method for predicting the optimum cycle time to schedule sootblowing using on-line process measurements. The optimum cycle times dynamically adjust to changing conditions resulting from boiler operation, fuel changes, or seasonal changes. The optimum cycle time is calculated four times per second for each heat trap of a boiler (10). The optimum conditions are based on economic criteria which account for heat trap fouling, rate of fouling of other heat traps (12, 13, 14, 16, and 18) within the boiler, and on-line boiler incremental steam cost.

Sootblowing optimization

A load control for a system comprised of a plurality of energy converters wherein a System Control Signal proportional to system load is developed and utilized to simultaneously adjust the rate of energy conversion of each of the converters in parallel in accordance with changes in system load. The rate of energy conversion for each converter, while operating under stead-state conditions for a predetermined period of time, is readjusted until its actual incremental cost of production is equal to a desired incremental cost.

Load control for energy converters

Control unit housing for a control panel mounted control station

A load control for a system comprised of a plurality of energy converters wherein the energy output of all converters is adjusted in parallel to maintain the total rate of energy output from the system equal to demand and wherein during steady-state conditions the rate of energy conversion for that converter having the lowest incremental cost is increased and simultaneously the rate of energy conversion for that converter having the highest incremental cost is decreased a like amount.

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Chesterland, OH, United States of America

Thomas J Scheib