基于模糊理论的局部通风机变频控制系统设计

Design of variable frequency control system for local ventilator based on fuzzy theory

  • 摘要: 现有局部通风机变频控制方法缺少对瓦斯突变量的预判,当大量瓦斯异常涌出时,调节存在一定滞后性,易导致瓦斯积聚。针对该问题,设计了基于模糊理论的局部通风机变频控制系统。采用瓦斯模糊控制器和风量模糊控制器实现模糊控制,对2个模糊控制器输出的控制量进行比较,根据较大值确定通风机变频情况,当两者相等时以瓦斯模糊控制为主。采用基于瓦斯涌出量的等级划分方法,以最远工况点对应风量为辅助,将通风机频率划分为4个等级。将掘进工作面瓦斯体积分数达到0.8%设置为升频条件,将瓦斯体积分数不大于0.6%或0.5%设置为降频条件,同时设定通风机降频后的供风量为达到降频条件时将回风流瓦斯体积分数控制在0.7%或0.6%所需的供风量。当大量瓦斯异常涌出时,通风机升频以降低瓦斯浓度,同时,通风机供风量可满足更大的瓦斯排放需求,为调整提供一定缓冲,克服变频控制滞后的缺点。试验结果表明:降频条件中瓦斯体积分数为0.5%,降频后供风量为达到降频条件时将回风流瓦斯体积分数控制在0.6%所需供风量,该条件下控制效果较好,但I级供风量略小于最远掘进距离处所需的最小供风量,可新设一个介于I级和II级之间的频率等级I*级,通过提高通风机频率来增加供风量,满足最远掘进距离处最小风量需求。

     

    Abstract: The existing variable frequency control method for local ventilator lacks prediction of gas outburst variable. When a large amount of gas emission abnormally, there is a certain lag in regulation, which is easy to lead to gas accumulation. To solve this problem, a variable frequency control system for local ventilator based on fuzzy theory is designed. Fuzzy control is realized by using gas fuzzy controller and air volume fuzzy controller. The control quantity output by two fuzzy controllers is compared. The frequency conversion situation of ventilator is determined according to the larger value. When the two are equal, the fuzzy control of gas is dominant. The classification method based on gas emission is adopted. With the air volume corresponding to the farthest working point as the auxiliary, the ventilator frequency is divided into 4 levels. The gas volume fraction of the heading working face reaching 0.8% is set as the frequency-increasing condition. The gas volume fraction not more than 0.6% or 0.5% is set as the frequency-reducing condition. Moreover, the air supply quantity of the ventilator after frequency reduction is set as the air supply volume required to control the gas volume fraction of return airflow at 0.7% or 0.6% when the frequency reduction condition is achieved. When a large amount of abnormal gas emission, the ventilator is increased in frequency to reduce the gas concentration. At the same time, the air supply volume of the ventilator can meet the greater gas discharge demand. The ventilator can provide a certain buffer for adjustment, and overcome the shortcomings of frequency conversion control lag. The test results show that the gas volume fraction is 0.5% under the condition of frequency reduction. The air supply volume after frequency reduction is the air supply volume required to control the gas volume fraction of return air at 0.6% when the frequency reduction condition is achieved. The control effect is good under this condition. But the air supply volume of level I is slightly less than the minimum air supply volume required at the farthest heading distance. The new frequency level I* between level I and level II can be set. The air supply volume can be increased by increasing the frequency of the ventilator to meet the minimum air supply volume requirement at the farthest heading distance.

     

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