International Journal of Pure and Applied Mathematics

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1 Volume 119 No , ISSN: (on-line version) url: ijpam.eu EFFICIENT DRUM LEVEL CONTROL FOR STEAM Dr.T.R.Rangaswamy 1, Dr.S. P. Vijayaragavan 2 Professor 1 2, Department of EEE, BIST, BIHER, Bharath University, Chennai. rangaswamy.eee@bharathuniv.ac.in Abstract This paper presents a performance based drum level control for steam generator in a thermal power plant using PID controller. The main objective of the drum level control is to ensure safe and efficient operation. Control of steam drum level is tougher than most other level control problems. In proposed method boiler drum level control is achieved based on performance with PID controller. Index Terms Steam generator, Boiler drum level control,simulink I. INTRODUCTION Steam generator is used purely for the electrical power generation. Ina Thermal power station, steam is produced in a boiler, is expanded in the prime mover (Turbine) and condensed in a condenser before feeding it into the boiler again. The turbine shaft is coupled with generator, which is used to produce electricity. One of the main part in thermal power plant is boiler that playsa vital role in steam generation. Boiler drum level control is critical to secure operation of the boiler and the steam turbine. The boiler drum-level control system maintains the constant level by means of regulating boiler feed water when the steam load changes or process s occur. Conventional PID (Proportional Integral Derivative) controller usedfor drum-level control is simple in structure, reliable in operation to certain extent in performance.three control schemes are adopted to control various s in system. Control schemes are feedback controller, feed forward controller and cascade controller. Avinash J. Gaikwad et al [9] [17] proposed selection and effectof steam drum level control method for multiple drum interacting loops.b.hemalatha et al [10] used labview to control boiler drum level. ManGyun Na et al [1] proposed auto-tuned PID controller to a linear model of steam generators. The PID gains of the proposed controller are tuned automatically. Man Gyun Na [2] designed an adaptive predictive controller for steam generator.gabriel A.et al [15] proposed Performance Evaluation of Egbin Power Station.A. Ghaffari [6] proposed An Optimization ApproachBased on Genetic Algorithm for Modeling Benson Type Boiler.Kwang Y. Lee et al [11] proposed Neural Network-Based ModelingForA Large-Scale Power Plant. Lijing Zhang et al [7] proposed Multiple Models Generalized Predictive Control for Superheated SteamTemperature Based On MLD Model. Min Xu et al [4] proposed Cascade generalized predictive control strategy for boiler drum level. Un-Chul Moon et al [14] proposed Adaptive Dynamic Matrix Control With Fuzzy-Interpolated Step-Response Model for a Drum-Type Boiler-Turbine System. Wen Tan et al [8] proposed Linear control of a boiler turbine unit. Yinsong Wang et al [12] proposed New Coordinated Control Design forthermal-power-generation Units. Yogesh Vora et al [13] Simulation Model for Stochastic Analysisand Performance Evaluation of Steam Generator System of a Thermal PowerPlant. F.Morilla e al [18] proposed Benchmark for PID control based on the Boiler Control Problem. Wei Wang et al [3] proposed Intelligence-Based Hybrid Control for Power Plant Boiler. Qingfeng Li et al [16] proposed Fieldbus H1 Networks for Steam Generator Level Control.Yu Daren et al [5] proposed Nonlinear Coordinated Control of Drum Boiler PowerUnit Based on Feedback Linearization. In the above mentioned paper different control techniques are used to maintain boiler drum level but it is not based on performance. In this proposed paper boiler drum level control is based on performance of boiler[17-22]. II. BOILER DRUM LEVEL CONTROL Boiler drum level control is critical for the protection of plant and equipment safety. It applies to maintain the equal high and low levels of water within the boiler drum[22-28]. The purpose of the drum level controller is to maintain the level at constant steam load. Different types of boiler drum level controls are as follows A. Single element drum level control In this control water level in the drum only considered.the process variable coming from the drum level transmitter is compared to a set point and the difference is a deviation value. This signal is given to the controller which generates corrective action output. The output is then passed to the 429

2 boiler feed water valve, which adjusts the level of feed water flow into the boiler drum. controller. Level element and steam flow element mainly correct for unmeasured s within the system[29-33]. Feed water flow element responds rapidly to variations in feed water demand either from the feed water pressure and steam flow rate of feed forward signal. Fig.1Single element drum level control system B. Two element drum level control The two element boiler drum level control system have two variables, drum level and steam flow to manipulate the feed water control valve. Steam flow load changes are act as a feed forward controller to the feed water control valve[34-39]. This feed forward controller provides an initial correction for the load changes. Imbalance between feed water mass flow and steam mass flow out into the drum is corrected by the level controller Fig.2Two elements drum level control system C. Three element drum level control Three elements are drum level, steam flow and feed water flow.by using cascade control mechanism, level element act as a primary loop and flow element act asa secondary loop and steam flow element act as a feed forward Fig.3 Three elements drum level control system III. CONTROL STRATEGIES AND SIMULATION Control strategies are necessary for any system to perform accurately. D. PID Controller A proportional-integral-derivative controller is a generic control loopfeedback mechanism widely used in industrial control systems.. A PID controller corrects the error between a measured process variable and a desired setpoint by calculating the value of error. The corrective action can adjust the process rapidly to keep the error minimal. The PID controller separately calculate the three parameters i.e. the proportional, the integral, the derivative values. The proportional value determines the reaction to the current error. The integral value determines the reaction based on the sum of recent errors as past error[40-45]. The derivative value determines the reaction based on the rate at which the error has been changing as a future error. By tuning these three constants in the PID controller algorithm, the controller can provide control action designed for specific process control requirements. Some applications may require only one or two parameters of the PID controller to provide the appropriate control on system. A PID controller will be called a PI, PD, P or I controller in the absence of the respective control actions. This is achieved by setting the gain of undesired control outputs to zero. PI controllers are very common, since derivative action is very sensitive to measurement noise and the absence of an integral value may prevent thesystem from reaching its target value due to control action. The simulation results are shown here for different control strategies. The relationship between the feed water flow rate and drum level for the boiler process are expressed by the following equations [3]. The process function, valve function and function is shown below. 430

3 Gp(s)= [0.25(-s+1)] / [s(2s+1)] (1) Gv(s) = 1/[0.15s+1] (2) Gd(s)=[ -0.25(-s+1)]/ [s(s+1)(2s+1) (3) Fig.4 Block diagram of boiler drum level control system Fig.7 Response of two element control Feed forwardcontrollertakes control action to avoid steam and allow drum level to maintain at its steady state. Fig.5 Response of single element control It has inverse response because of right hand plane zero in the process transfer function. Fig.8 Response of two element control with feed water Drum level get deteriorated due to increase in feedwater flow rate. Fig.6 Response of single element control with steam Since steam flow rate is rapidly increased, causes steam pressure to drop momentarily. This drop of pressure causes air bubbles to increase in size and the water level to increase. Fig.9 Response of three element drum level control IV.RESULT AND ANALYSIS The simulation block diagrams are implemented under MATLAB software using the method of PID controller as 431

4 Zeigler-Nichol Method. For the step input, the performance of the boiler for different control strategies is compared. The parameter considered are rise time, settling time, peakovershoot, ISE and IAE. Table 3 shows the comparison of the boiler performances through different controller. TABLE.1 parameter controller Single element control Single element control with steam Two element control Two element control with feed water flow Three element control Rise time (sec) Settling time (sec) Overshoot ISE IAE REFERENCES 1. Nimal, R.J.G.R., Hussain, J.H., Effect of deep cryogenic treatment on EN24 steel, International Journal of Pure and Applied Mathematics, V-116, I-17, PP , 2. Parameswari, D., Khanaa, V., Deploying lamport clocks and linked lists, International Journal of Pharmacy and Technology, V-8, I-3, PP , Parameswari, D., Khanaa, V., Case for massive multiplayer online role-playing games, International Journal of Pharmacy and Technology, V-8, I-3, PP , Parameswari, D., Khanaa, V., Deconstructing model checking with hueddot, International Journal of Pharmacy and Technology, V-8, I-3, PP , Parameswari, D., Khanaa, V., The effect of self-learning epistemologies on theory, International Journal of Pharmacy and Technology, V-8, I-3, PP , Pavithra, J., Peter, M., GowthamAashirwad, K., A study on business process in IT and systems through extranet,, V-116, I-19, PP , 7. Pavithra, J., Ramamoorthy, R., Satyapira Das, S., A report on evaluating the effectiveness of working capital management in googolsoft technologies, Chennai,, V-116, I-14, PP , 8. Pavithra, J., Thooyamani, K.P., A cram on consumer behaviour on Mahindra two wheelers in Chennai,, V-116, I-18, PP-55-57, 9. Pavithra, J., Thooyamani, K.P., Dkhar, K., A study on the air freight customer satisfaction, International Journal of Pure and Applied Mathematics, V-116, I-14 Special Issue, PP , 10. Pavithra, J., Thooyamani, K.P., Dkhar, K., A study on the working capital management of TVS credit services limited, International Journal of Pure and Applied Mathematics, V-116, I-14, PP , 11. Pavithra, J., Thooyamani, K.P., Dkhar, K., A study on the analysis of financial performance with reference to Jeppiaar Cements Pvt Ltd, International Journal of Pure and Applied Mathematics, V-116, I-14, PP , 12. Peter, M., Dayakar, P., Gupta, C., A study on employee motivation at Banalari World Cars Pvt Ltd Shillong,, V-116, I-18, PP , 13. Peter, M., Kausalya, R., A study on capital budgeting with reference to signware technologies, International Journal of Pure and Applied Mathematics, V-116, I-18, PP-71-74, 14. Peter, M., Kausalya, R., Akash, R., A study on career development with reference to premheerasurgicals,, V-116, I-14, PP , 15. Peter, M., Kausalya, R., Mohanta, S., A study on awareness about the cost reduction and elimination of waste among employees in life line multispeciality hospital, International Journal of Pure and Applied Mathematics, V-116, I-14, PP , 16. Peter, M., Srinivasan, V., Vignesh, A., A study on working capital management at deccan Finance Pvt Limited Chennai, International Journal of Pure and Applied Mathematics, V-116, I-14, PP , 17. Peter, M., Thooyamani, K.P., Srinivasan, V., A study on performance of the commodity market based on technicalanalysis, International Journal of Pure and Applied Mathematics, V-116, I-18, PP , 18. Philomina, S., Karthik, B., Wi-Fi energy meter implementation using embedded linux in ARM 9, Middle - East Journal of Scientific Research, V-20, I-12, PP , Philomina, S., Subbulakshmi, K., Efficient wireless message transfer system, International Journal of Pure and Applied Mathematics, V-116, I-20, PP , 20. Philomina, S., Subbulakshmi, K., Ignition system for vechiles on the basis of GSM, International Journal of Pure and Applied Mathematics, V-116, I-20 Special Issue, PP , 21. Philomina, S., Subbulakshmi, K., Avoidance of fire accident by wireless sensor network, International Journal of Pure and Applied Mathematics, V-116, I-20, PP , 22. Pothumani, S., Anuradha, C., Monitoring android mobiles in an industry, International Journal of Pure and 432

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