Using OPC Technology to Support the Study of Advanced Process Control

Using OPC Technology to Support the Study of Advanced Process Control

This post is an excerpt from the journal ISA Transactions. All ISA Transactions articles are free to ISA members, or can be purchased from Elsevier Press.

 

 

Abstract: OPC, originally the object linking and embedding (OLE) for process control, brings a broad communication opportunity between different kinds of control systems. This paper investigates the use of OPC technology for the study of distributed control systems (DCS) as a cost effective and flexible research tool for the development and testing of advanced process control (APC) techniques in university research centers. Co-simulation environment based on Matlab, LabVIEW and TCP/IP network is presented here. Several implementation issues and OPC based client/server control application have been addressed for TCP/IP network. A nonlinear boiler model is simulated as OPC server and OPC client is used for closed loop model identification, and to design a model predictive controller (MPC). The MPC is able to control the NOx emissions in addition to drum water level and steam pressure.

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2006-2018 Elsevier Science Ltd. All rights reserved.

 

How to Detect Defects in Rolling Element Bearings Used in Manufacturing Processes

How to Detect Defects in Rolling Element Bearings Used in Manufacturing Processes

This post is an excerpt from the journal ISA Transactions. All ISA Transactions articles are free to ISA members, or can be purchased from Elsevier Press.

 

 

Abstract: The active health monitoring of rotordynamic systems in the presence of bearing outer race defect is considered in this paper. The shaft is assumed to be supported by conventional mechanical bearings and an active magnetic bearing (AMB) is used in the mid of the shaft location as an exciter to apply electromagnetic force to the system. We investigate a nonlinear bearing-pedestal system model with the outer race defect under the electromagnetic force. The nonlinear differential equations are integrated using the fourth-order Runge–Kutta algorithm. The simulation and experimental results show that the characteristic signal of outer race incipient defect is significantly amplified under the electromagnetic force through the AMBs, which is helpful to improve the diagnosis accuracy of rolling element bearing’s incipient outer race defect. The rolling element bearing is one of the most common components in rotating machinery. The health condition of these bearings directly determines the performance of the rotating machinery. Defects in bearings that may occur during operation or the manufacturing process can cause vibration, noise, and even system failure. It is thus critical to detect the defects in bearings at their initial stage to prevent catastrophic damage or failures to the rotating machine, resulting in plant downtime and reduced efficiencies.  

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Tuning Strategies and the Fragility of Fractional-Order PID Controllers

Tuning Strategies and the Fragility of Fractional-Order PID Controllers

This post is an excerpt from the journal ISA Transactions. All ISA Transactions articles are free to ISA members, or can be purchased from Elsevier Press.

 

 

Abstract: This paper analyzes the fragility issue of fractional-order proportional-integral-derivative controllers applied to integer first-order plus-dead-time processes. In particular, the effects of the variations of the controller parameters on the achieved control system robustness and performance are investigated. Results show that this kind of controller is more fragile with respect to the standard proportional-integral-derivative controllers and therefore significant attention should be paid by the user in their tuning. A properly designed control system must provide an effective trade-off between performance and robustness. One of the main reasons to investigate the fragility of fractional-orde PID controllers is to enable an engineer or technician to use alternative strategies for tuning the controller.

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Low Cost Test Rig for a Standalone Wind Energy Conversion System

Low Cost Test Rig for a Standalone Wind Energy Conversion System

This post is an excerpt from the journal ISA Transactions. All ISA Transactions articles are free to ISA members, or can be purchased from Elsevier Press.

 

 

Abstract: In this paper, a contribution to the development of low-cost wind turbine (WT) test rig for stator fault diagnosis of wind turbine generator is proposed. The test rig is developed using a 2.5 kW, 1750 RPM DC motor coupled to a 1.5 kW, 1500 RPM self-excited induction generator interfaced with a WT mathematical model in LabVIEW. The performance of the test rig is benchmarked with already proven wind turbine test rigs. In order to detect the stator faults using non-stationary signals in self-excited induction generator, an online fault diagnostic technique of DWT-based multi-resolution analysis is proposed. It has been experimentally proven that for varying wind conditions wavelet decomposition allows good differentiation between faulty and healthy conditions leading to an effective diagnostic procedure for wind turbine condition monitoring.

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Nonlinear Predictive Control of a Boiler-Turbine Unit

Nonlinear Predictive Control of a Boiler-Turbine Unit

This post is an excerpt from the journal ISA Transactions. All ISA Transactions articles are free to ISA members, or can be purchased from Elsevier Press.

 

 

Abstract: This paper details development of a model predictive control (MPC) algorithm for a boiler-turbine unit, which is a nonlinear multiple-input multiple-output process. The control objective is to follow set-point changes imposed on two state (output) variables and to satisfy constraints imposed on three inputs and one output. In order to obtain a computationally efficient control scheme, the state-space model is successively linearized on-line for the current operating point and used for prediction. In consequence, the future control policy is easily calculated from a quadratic optimization problem. For state estimation the extended Kalman filter is used. It is demonstrated that the MPC strategy based on constant linear models does not work satisfactorily for the boiler-turbine unit whereas the discussed algorithm with on-line successive model linearization gives practically the same trajectories as the truly nonlinear MPC controller with nonlinear optimization repeated at each sampling instant.

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