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Analysis of macrocycle schedules for an alternative of FF-based feedforward control
(2019-04-01)
Julsereewong, Amphawan
;
Pannil, Pittaya
This paper focuses on analyzing the macrocycle schedules generated for an alternative implementation of Foundation Fieldbus (FF)-based feedforward control with hybrid architecture. The interested alternative control strategy is based on the use of the bias/gain (BG) function block to create feedforward summing function outside a proportional-integral-derivative (PID) function block for use to meet special operation requirements. An FF temperature control loop connected to the DeltaV distributed control system (DCS) providing built-in capability to execute function blocks in an H1 interface card is utilized as a case study to examine the effects of eight different configuration schemes on macrocycle schedules and function block synchronizations. Experimental results obtained from major configuration schemes by placing the PID block in the DCS host controller, the H1 interface card, and the temperature transmitter show that function block allocation affects the control performance to anticipate process disturbance effects.
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Integration of hart and ff h1 devices into distributed control system for feedforward control in revamping existing plants
(2019-02-01)
Thepmanee, Teerawat
;
Julsereewong, Amphawan
;
Pongswatd, Sawai
To revamp existing process plants that use Highway Addressable Remote Transducer (HART) communication technology, reusing the existing instruments which are still available in the market to combine with new Foundation Fieldbus (FF) H1 instruments in the same control system can become a cost-effective strategy for digital modernization. This paper aims at presenting an engineering method based on IEC 61804 standard for integrating a HART field device and FF H1 devices into a distributed control system (DCS) to operate together in a feedforward control loop. To verify the performance of the proposed method, the feedforward on temperature control configured and handled on the DeltaV DCS is employed as an illustrative case study. Moreover, how different analog-input (AI) function block assignments to the HART and FF transmitters for measuring the controlled variable and disturbance input as well as how different proportional-integral-derivative (PID) function block allocations to the DCS controller and FF field devices affect the H1 segment macrocycle schedules and network traffic loads is also analyzed. Experimental results obtained from some control configuration schemes demonstrate that the combined HART-FF H1 technique can maintain the controlled variable at the setpoint in the presence of disturbances for feedforward control.
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Communication schedule optimization for foundation fieldbus H1 segment with dual cascade control loops
(2016-11-01)
Sangsuwan, Thaksin
;
Pongswatd, Sawai
;
Julsereewong, Amphawan
This paper proposes a method for optimizing communication schedules of dual cascade control loops within the same Foundation Fieldbus (FF) H1 segment. Integrated Harmonas-DEO host system is utilized as a configuration tool for building control strategy and scheduling macrocycle of the studied H1 segment, which consists of two level-to-flow cascade control loops. Communication schedule optimization of two different cases of assigning control functions to run in the field devices is described. Method validation is based on the use of three metrics: latency improvement, publication gap improvement, and macrocycle utilization improvement. Comparison results between the natural macrocycle and optimized macrocycle show that the proposed method can improve not only the latency of control loop but also the availability of communication bandwidth.
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Communication schedule optimization of cascade control using foundation fieldbus
(2016-01-01)
Sangsuwan, Thaksin
;
Pongswatd, Sawai
;
Julsereewong, Amphawan
;
Morioka, Yoshitsugu
;
Amano, Yoshiharu
This paper presents a technique to optimize the communication schedules generated for synchronization of Foundation Fieldbus H1 devices in cascade control loop. A level-to-ﬂow cascade control operated by the Harmonas-DEO host system is examined as an illustrative case study. Major objectives of the optimization are not only to minimize the latency of the control loop but also to maximize the availability of the network bandwidth. The proposed technique can be applied for H1 segment macrocycle schedules performing the control functions in both of the host controller and the ﬁeld devices. Three examples for optimizing communication schedules generated from diﬀerent control block assignments are described. The validation of the optimization methods can be determined by using two metrics: control loop latency improvement and publication gap availability improvement. Experimental results conﬁrm that the proposed technique works eﬀectively to operate the studied H1 segment for cascade control without any problems.
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Foundation Fieldbus segment scheduling for fast loop controls
(2013-02-15)
Julsereewong, Amphawan
;
Julsereewong, Prasit
;
Harntujit, Piyaporn
In this article, a technique to obtain fast loop controls using Foundation Fieldbus-based control in the field strategy is presented. Macrocycle schedules for running a single control loop and running two control loops on a segment are examined. Performances of the proposed technique were studied through calculated macrocycle timing schedules produced by the DeltaV and CentumVP systems. Surpassing the traditional Distributed Control System (DCS) approach with control in the host, the proposed technique offers significant improvement in segment schedules with minimizing network scheduled communications. © 2013 ICIC International.

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