| Induced draft fan is an important equipment for adjusting coal-fired boiler hearthnegative pressure. In most of the the thermal power plant, the air volume of induceddraft fan was controlled by changing the baffle opening degree at present. Because ofthe limit of technology and fund, this method leads to a lot of energy consumption in thethrottling loss of the pipeline. As to speed control, variable frequency speed regulationsystem can realize the continuous speed control of equipment and achieve significantenergy saving effect by adjusting the motor input frequency. In this paper, aiming athigh energy consumption problems that exist in the induced draft fan control system, thePLC, frequency converter and the MCGS configuration are used in induced draft fancontrol system. The purpose of this approach is to obtain real-time and convenientsystem’s control and maximum energysaving, thus the economic benefit is improved.There are three aspects of work completed as follows：Firstly, the reasons of high energy consumption was summarized by studying theworking principle and the actual operation of induced draft fan for boiler in power plant,so the necessity of the energy saving is put forward. And the feasibility of using thefrequency control of motor speed was determined by researching different speed controlmethods. Then the theoretical study of the method was carried on.Secondly, the variable universe fuzzy control based on double precision searchalgorithm was applied to the closed loop control of hearth negative pressure in order toacquire more excellent precision of control system. At the same time, the new strategyof using double precision search algorithm to optimize the geometric factor inparameters is put forward. To compare with other existed control methods, the result of Matlab simulation indicated that the speed and accuracy of parameter optimization areimproved significantly when the variable universe fuzzy control based on doubleprecision search algorithm was applied to speed regulation of induced draft fan forboiler.Finally, the project of hardware configuration and program of energy-savingcontrol system of induced draft fan are designed by Mitsubishi PLC, whose type isFX-2N-32MT and extensibility is better, frequency converter, which can be used forfrequency conversion, touch screen, which can be used as friendly man-machineinterface and MCGS,which has powerful configuration monitoring function.In the study process of the whole system, the main research was the application ofdouble precision search algorithm in the parameter optimization of variable universefuzzy control algorithm. The project of hardware configuration logic based on PLC、frequency converter and configuration software MCGS was designed. The researchshows that the algorithm improves the accuracy and adaptability as well as reducing theerror of the algorithm itself firstly, besides the designed human-computer interactionsystem can make the control more convenient and timely. To sum up, the achievementof this study on the energy-saving control of induced draft fan in the actual productionhas some practical value. |
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