US 2026/0023375 A1Published application

Methods and systems for decentralized steady state error cancellation in large scale, interconnected systems

AssigneeKing Fahd University of Petroleum and Minerals

InventorsAhmed MASOUD, Mahmoud KASSAS

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Abstract

A decentralized controller and methods for steady-state error cancellation in a plant system with multiple components comprises an error control loop for each component, where each error control loop includes steady-state control signals and plant output signals. Each error control loop receives a set point value and plant output signals and generates error signals. The error signals are amplified to produce amplified error control signals. A trigger circuit, connected to output of the multiplier, detects steady-state events in the error signals and generates trigger pulses accordingly. A sample and hold circuit receives the trigger pulses and the negative steady-state control signals and generates a steady-state error cancellation signal which is then injected back into the error control loop to mitigate steady-state errors. The sample and hold circuit also generates a reset signal which clears an integrator in the trigger circuit to prevent integrator wind-up.

Claims19

Dependent claims

An industrial plant system having N interconnected industrial processes, comprising:

N actuators, each actuator operating to actuate one industrial process of the N interconnected industrial processes, each actuator being a control valve, an electrical actuator, or a piezoelectric actuator;
N sensors, each sensor sensing an output signal from one industrial process of the N interconnected industrial processes;
and
a decentralized controller with steady state error cancellation, the decentralized controller providing steady state control signals to the N actuators, so as to control the N interconnected industrial processes, wherein:
the decentralized controller comprises N error control loops,
each actuator of the N actuators is controlled by one corresponding error control loop of the N error control loops, and
for an i-th actuator, with i=1, 2, . . . , N,
a corresponding i-th error control loop obtains a set point value Ri assigned to the i-th actuator, acquires an output signal Xi(t) from an i-th sensor, which senses the output signal Xi(t) from an i-th industrial process, and applies a steady state control signal ui(t) to the i-th actuator, such that the i-th actuator operates at an operating condition specified by the set point value Ri,
the i-th error control loop further includes a first multiplier, an amplifier, a trigger circuit, a sample and hold circuit, and an adder,
the first multiplier is configured to:
obtain the set point value Ri, acquire the output signal Xi(t), and multiply the set point value Ri by a negative value of the output signal Xi(t) to generate an error signal ei(t),
the amplifier is connected to an output terminal of the first multiplier and configured to:
amplify the error signal ei(t) by a gain Ki, and generate an amplified error control signal Ki·ei(t),
the trigger circuit is connected to the output terminal of the first multiplier and configured to:
receive the error signals ei(t), detect a steady state event of the error signals ei(t), and generate a trigger pulse gi(t) based on detecting the steady state event,
the sample and hold circuit is configured to;
receive the trigger pulse gi(t) from the trigger circuit, the steady state control signals ui(t) from the adder, generate a steady state error cancellation signal Z(t)i based on the trigger pulse gi(t) and a negative value of the steady state control signal ui(t), and inject the steady state error cancellation signal Z(t)i into the adder, and
the adder is configured to:
add the amplified error signals Ki·ei(t) and the steady state error cancellation signal Z(t)i to generate the steady state control signals ui(t), and apply the steady state control signals ui(t) to the i-th actuator to control operation thereof.

16 more elements

A method for controlling an industrial plant system having N interconnected industrial processes, the method comprising:

establishing N actuators, each actuator operating to actuate one industrial process of the N interconnected industrial processes, each actuator being a control valve, an electrical actuator, or a piezoelectric actuator;
establishing N sensors, each sensor sensing an output signal from one industrial process of the N interconnected industrial processes;
establishing a decentralized controller including N error control loops, wherein each actuator of the N actuators is controlled by one corresponding error control loop of the N error control loops, so as to control one corresponding industrial process of the N interconnected industrial processes;
and
for an i-th actuator, with i=1, 2, . . . , N, by a corresponding i-th error control loop, performing steady state error cancellation to generate a steady state control signal ui(t) to control operation of the i-th actuator,
wherein the i-th error control loop further includes a first multiplier, an amplifier, a trigger circuit, a sample and hold circuit, and an adder, and
the step of performing steady state error cancellation further comprises:
by the first multiplier, obtaining a set point value Ri assigned to the i-th actuator, acquiring an output signal Xi(t) from an i-th sensor, which senses the output signal Xi(t) from an i-th industrial process, and multiplying the set point value Ri by a negative value of the output signal Xi(t) to generate an error signal ei(t),
by the amplifier connected to an output terminal of the first multiplier, amplifying the error signal ei(t) by a gain Ki and generating an amplified error control signal Ki·ei(t),
by the trigger circuit connected to the output terminal of the first multiplier, receiving the error signal ei(t), detecting a steady state event of the error signal ei(t), and generating a trigger pulse gi(t) based on detecting the steady state event,
by the sample and hold circuit, receiving the trigger pulse gi(t) from the trigger circuit, receiving the steady state control signal ui(t) from the adder, generating a steady state error cancellation signal Z(t)i based on the trigger pulse gi(t) and a negative value of the steady state control signal ui(t), and injecting the steady state error cancellation signal Z(t)i into the adder, and
by the adder, adding the amplified error signals Ki·ei(t) and the steady state error cancellation signal Z(t)i to generate the steady state control signals ui(t), and applying the steady state control signals ui(t) to the i-th actuator to control operation thereof, such that the i-th actuator operates at an operating condition specified by the set point value Ri.

9 more elements

A non-transitory computer readable medium having instructions stored therein that, when executed by one or more processors, cause the one or more processors to perform a method for controlling an industrial plant system having N interconnected industrial processes, the industrial plant system further comprising N actuators and N sensors, each actuator operating to actuate one industrial process of the N interconnected industrial processes, each actuator being a control valve, an electrical actuator, or a piezoelectric actuator, each sensor sensing an output signal from one industrial process of the N interconnected industrial processes, the method comprising:

establishing a decentralized controller including N error control loops, wherein each actuator of the N actuators is controlled by one corresponding error control loop of the N error control loops;
and
for an i-th actuator, with i=1, 2, . . . , N, by a corresponding i-th error control loop, performing steady state error cancellation to generate a steady state control signal u,(t) to control operation of the i-th actuator,
wherein the i-th error control loop further includes a first multiplier, an amplifier, a trigger circuit, a sample and hold circuit, and an adder, and
the step of performing steady state error cancellation further comprises:
by the first multiplier, obtaining a set point value Ri assigned to the i-th actuator, acquiring an output signal Xi(t) from an i-th sensor, which senses the output signal Xi(t) from an i-th industrial process, and multiplying the set point value Ri by a negative value of the output signal Xi(t) to generate an error signal ei(t),
by the amplifier connected to an output terminal of the first multiplier, amplifying the error signal ei(t) by a gain Ki and generating an amplified error control signal Ki·ei(t),
by the trigger circuit connected to the output terminal of the first multiplier, receiving the error signal ei(t), detecting a steady state event of the error signal ei(t), and generating a trigger pulse gi(t) based on detecting the steady state event,
by the sample and hold circuit, receiving the trigger pulse gi(t) from the trigger circuit, receiving the steady state control signal ui(t) from the adder, generating a steady state error cancellation signal Z(t)i based on the trigger pulse gi(t) and a negative value of the steady state control signal ui(t), and injecting the steady state error cancellation signal Z(t)i into the adder, and
by the adder, adding the amplified error signals Ki·ei(t) and the steady state error cancellation signal Z(t)i to generate the steady state control signals ui(t), and applying the steady state control signals ui(t) to the i-th actuator to control operation thereof, such that the i-th actuator operates at an operating condition specified by the set point value Ri.

7 more elements

Dependencies are inferred from the claim text.