The traditional automatic control of CBM is easy to overshoot and lag

making the automatic control technology of CBM recovery just stay in the level of data acquisition and simple remote control. Therefore

the problems existing in the traditional PID control algorithm in the automatic control of CBM drainage is discussed

and the causes of over harmonic and lagging phenomenon are analyzed

so as to put forward the loose coupled automatic control technology of CBM wellbore flow rule model combined with PID control algorithm. The upper computer adopts digital analog multi parameters coupling to reduce the difficulty of automatic control

after that

initializes user instructions. In the loosens coupling algorithm

the digital analog parameters are used as the error range value to improve the efficiency of PID control and effectively make up for the shortcomings of traditional one. Loose coupling automatic control can also avoid the destructive development of single parameter control

which is suitable for many unique production modes of CBM

such as slow flow pressure reduction by constant casing pressure and constant production

and slow casing pressure reduction by steady flow pressure. It has a high popularization value in the automatic drainage of CBM.