International Journal of Electronics and Computer Science Engineering

Available Online at www.ijecse.org

62

ISSN- 2277-1956

A Comparative Study on Temperature Control of CSTR using PI Controller, PID Controller and PID (Two Degree of Freedom) Controller Bikash Dey 1

1

, Lusika Roy

2

Assistant Professor, Department of Electronics and Communication Engineering, JIS College of Engineering, Kalyani. e-mail: [email protected] 2 Assistant Professor, Department of Electrical Engineering , JIS College of Engineering, Kalyani. e-mail: [email protected]

Abstract- This paper present three different control strategies based on PI Control, PID control and Two degree of freedom PID control for Continuous Stirred Tank Reactor (CSTR).CSTR which offers a diverse range of application in the field of chemical engineering as well as in the control engineering and is an attractive research area for process control researchers. Our objective is to control the temperature of CSTR in presence of the set point. MATLAB SIMULINK software is used for model design and simulation.

Keywords -— PI controller, PID Controller, PID controller (2DOF), Chemical Temperature, CSTR.

I. INTRODUCTION Controlling CSTR is an attractive issue for control engineers for its dynamics (non linear).A control mechanism is needed to cancel the negative impact due to nonlinearities which may cause undesired effect in chemical plants. Errors and random disturbances are modelled by using the controller. In search of getting the most linear response PI, PID & 2DOF PID controllers are used in this paper and the output responses are plotted. In this simulation based work maintaining the CSTR at steady state operating point is the main issue. PI and PID controllers are ideal for controlling non linear process.PID controllers can be used for performance increase with respect to system variations[2],[3].In this paper 2DOF PID controller is also used because of its better control on non linear process. In order to achieve accurate and acceptable results fine tuning of the PI, PID & 2 DOF PID is necessary and in this paper that is tried and presented. II. MATHEMATICAL MODELLING OF THE CSTR Controlling CSTR is an attractive issue for control engineers for its dynamics (non linear).A control mechanism is needed to cancel the negative impact due to nonlinearities which may cause undesired effect in chemical plants. Errors and random disturbances are modelled by using the controller. In search of getting the most linear response PI, PID & 2DOF PID controllers are used in this paper and the output responses are plotted. In this simulation based work maintaining the CSTR at steady state operating point is the main issue. PI and PID controllers are ideal for controlling non linear process.PID controllers can be used for performance increase with respect to system variations[2],[3].In this paper 2DOF PID controller is also used because of its better control on non linear process. In order to achieve accurate and acceptable results fine tuning of the PI, PID & 2 DOF PID is necessary and in this paper that is tried and presented.

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63 A Comparative Study on Temperature Control of CSTR using PI Controller, PID Controller and PID (Two Degree of Freedom) Controller

Figure (1): Tank reactor with jacket (for cooling) and with continues stirring [4]. Using state space modelling [4] the reactor process transfer function (Gp) was found as

Table for Reactor Parameter’s value [4]. Parameter Ea ko U pcp V

Values 32.400 16.96*1012 75 53.25 85

Unit Btu/lbmol Hr-1 Btu/hrft2 oF Btu/ft3 oF Ft3

R

1.987

Btu/lbmol oF

F

340

Ft3/hr

Caf

0.132

Lbmol/ft3

Tf

60

o

F

It is seen that the process has inverse response with delay time as well as overshoot. To overcome this problem and to obtain the desired response, we are using of PI controller, PID controller and PID (two degree of freedom). For that, the controller parameters are calculated. The desired parameters for the PID controller are the proportional gain (KP) integral gain (KI) and the differential gain (KD) can be calculated by the Automatic PID tuning method in MATLAB software.

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IJECSE, Volume3, Number 1 Bikash Dey and Lusika Roy

III. SIMULATION AND RESULTS The CSTR with PI controller, PID controller and PID (two degree of freedom) are shown in below. After the simulation, it has been observed that the overshoot and the settling time has been reduced significantly when using 2 degrees of freedom (2 DOF) PID as shown the following table. The 2 DOF PID also helps to suppress the effect of application of the perturbation at arbitrary instance of time (as shown in the output response plot).The results of the application of different controllers are shown in the following table. Controllers PI PID PID (2DOF)

Rise time 0.556 sec 0.75 sec 0.87 sec

Settling Time 2.54 sec 1.76 sec 1.41 sec

Figure (2): Single loop CSTR with PI controller

Figure (2a): Output Response of PI controller

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Overshoot 6.45 % 2.32 % 0%

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65 A Comparative Study on Temperature Control of CSTR using PI Controller, PID Controller and PID (Two Degree of Freedom) Controller

Figure (3): Single loop CSTR with PID controller

Figure (3a): Output Response of PID controller

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IJECSE, Volume3, Number 1 Bikash Dey and Lusika Roy

Figure (4): Single loop CSTR with PID (2DOF) controller

Figure (4a): Output Response of PID (2DOF) controller

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67 A Comparative Study on Temperature Control of CSTR using PI Controller, PID Controller and PID (Two Degree of Freedom) Controller

IV. CONCLUSION In this paper application of different controllers (PI, PID & 2 DOF PID) on a CSTR system has been studied and the results are plotted. It has been found that 2 DOF PID performs best in terms of overshoot and settling time reduction and suppressing the effect of applied perturbation on the system. In this case, the overshoot been reduced to 0 % and a very small settling time (1.41 sec) has been achieved. REFERENCES [1] Sandeep kumar, “Temperature Control of CSTR using PID and PID (Two Degree of Freedom) Controller”, International Journal of Advanced Research in Computer Science and Software Engineering, Volume 2, Issue 5, May 2012 ISSN: 2277 128X. [2] S.F.Rezeka, N.M.Elsodany and N.A.Maharem, “Fuzzy Gain Scheduling Control of a Stepper Motor Driving a Flexible Rotor”, European Journal of Scientific Research, Vol.39, pp.50-63, 2010. [3] S.Kamalasadan, “A New I intelligent Control for the Precision Tracking of Permanent Magnet Stepper Motor”, IEEE, Power Engineering Society General Meeting, 2007. [4] Sandeep kumar , “Temperature Control of CSTR using PID and PID (Two Degree of Freedom) Controller” International Journal of Advanced Research in Computer Science and Software Engineering, Volume 2, Issue 5, May 2012 ISSN: 2277 128X. [5] M. Obaid Ali, S. P. Koh, and K. H. Chong, S.K.Tiong and Z. Assi Obaid , “Genetic Algorithm Tuning Based PID Controller for Liquid-Level Tank System” , Proceedings of the International Conference on Man-Machine Systems , MALAYSIA, 2009. [6] U. Sabura Banu , G. Uma, “ANFIS Gain Scheduled CSTR with Genetic Algorithm Based PID Minimizing Integral Square Error”, International Conference on Information and Communication Technology in Electrical Science,.2007 [7] B. Wayne Bequette, “Process Dynamics: Modelling, Analysis and Simulation”, published by Prentice-Hall, 1998. [8] M. Nikravesh ,A.E. Farell,T.G. Stanford , “ Control of non isothermal CSTR with time varying parameters via dynamic neural network control (DNNC) ” , Chemical Engineering Journal,vol 76,pp.1-16,2000. [9] X. Liu T.Huang , X.Tang, and H. Xin ,“ Design of Self-Adaptive PID Controller Based on Least square method ”,IEEE,Third International Conference on Genetic and Evolutionary Computing ,2009. [10] A.MohammadZadeh, E.Atashpaz Gargari, C.Lucas, “Vehicle Fuzzy Controller Design Using Imperialist Competitive Algorithm”, IEEE, World Congress on Computational Intelligence, 2008. [11] Schmidt, Lanny D. (1998) The Engineering of Chemical New York Oxford University Press. ISBN 0-19510588-5. [12] Fried land B.“Advanced Control System Design”, Prentice Hall, New Jersey, 1996. [13] Jiri Vojtesek and Petr Dostal, “Simulation analysis of CSTR” TomasBata University in Zlin .

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IJECSE, Volume3, Number 1 Bikash Dey and Lusika Roy

[14] Luis E. Zarate, Peterson Resende, & M. Benjamin, “A CSTR Control”. Annual conference of IEEE, 2001.Ioannou and J. Sun, “Robust Adaptive Control”,PrenticeHall,1996514. [15] K.J. °Astr¨om and B. Wittenmark, Adaptive control, Seider, W.D., J.D. Seader and D.R. Lewin “ Process DesignPrinciples”, Wiley (1999). [16] Adaptive control systems: techniques and applications By V. V.Chalam:34-98. [17] Isidori, A. “Nonlinear control systems”.New York: pringer Verlag, 1995:12-56 [8] R.Marino and P. Tomei, Nonlinear Adaptive Design Geometric, Adaptive, and Robust, Printice Hall International (UK) Limited,London, 1995. [19] Yun Li,Kiam Heong Ang and Gregory C.Y.Chong, “PID Control System Analysis and Design – Problems, emedies, and Future Directions”. IEEE control system magazine, February2006. [20] Cohen, G.H., Coon, G.A. "Theoretical consideration of retarded control", Trans. ASME vol. 75, pp.827-834, 1953. [21] Levine, W.S. ed., the control handbook, CRC Press, 1995 [12] Åström, K.J., Hägglund, T., “PID Control – Theory, Design and Tuning”, Instrument Society of America, Research Triang Park, NC, 2nd ed., 1995. [22] D. Krishnaa,K. Suryanarayanab,G. Aparnab, and R. Padma Sreeb “Tuning of PID Controllers for Unstable Continuous Stirred Tank Reactors” International Journal of Applied Science and Engineering 2012. 10, 1: 1-18

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