Multivariable deduction, predication and control method for middle-speed coal pulverizer

Abstract

The invention discloses a multivariable deduction, predication and control method for a middle-speed coal pulverizer. Through an extended Kalman filtering method, the coal output amount of a coal pulverizer is estimated in real time through a pressure difference between an inlet and an outlet of the coal pulverizer and also through the outlet temperature, an estimation value of the coal output amount is taken as new controlled amount to be added to a control system, and the rotating speed of the coal pulverizer is additionally adopted to serve controlled amount. In this way, load instructions of the coal pulverizer can be quickly responded, and the time delay of a pulverizing system side can be shortened. A model prediction control algorithm is employed by the control method. Compared with a conventional PID control method, the multivariable deduction, predication and control method has the advantages that the primary air quantity and the outlet temperature can be better adjusted, and disturbance caused by changes of the quality of coal can be well prevented.

Description

technical field [0001] The invention relates to the field of thermal power plant control, in particular to a control method for a medium-speed coal pulverizer. Background technique [0002] The boiler pulverizing system is an important part of the thermal power plant, and its operation safety, reliability and economy directly affect the safety, reliability and economy of the boiler unit. With the continuous improvement of thermal power unit capacity and parameters, thermal power plants generally adopt medium-speed mill direct blowing pulverization system. At present, 300MW units are equipped with 4 medium-speed coal mills, 600-1000MW units are equipped with 5 sets, and the maximum output of a single medium-speed mill is 45t / h. The traditional medium-speed coal mill control scheme uses the opening of the cold air valve and the opening of the hot air valve as the control quantities, the primary air volume and the outlet temperature as the controlled quantities, and uses the P...

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Problems solved by technology

[0003] The medium-speed coal pulverizer system is a nonlinear system with strong coupling, large lag, and multi-input-multiple output. Its dynamic characteristics change in a wide range with the change of operating conditions. The traditional PID plus decoupling control method is difficult Accurate control will lead to poor response of the unit to the AGC command, unstable control of the outlet temperature of the coal mill, and affect the safety and economy of operation

On the other hand, because the coal output of the coal mill is difficult to measure online, the traditional control system adjusts the coal output of the coal mill in time when the load of the unit changes, resulting in a large delay between the load response and the command

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