| Since 1990s,the fierce competition from the development of petroleum exploration and exploitation and oil-gas exploration becoming difficult at present,the drilling contractors require equipments to reduce the drilling cost and exploitation cost. and to increase speed and to cut down oil-producing cycle.To meet above-mentioned requirements,modern drilling equipments must employ the new control technology and develope the new drilling control system.With the development of drilling technology reqiring and relevant new technologies,automatic drilling based on frequency control of motor speed appeared.In 1996s,after the first automatic drilling device in the world was born,automatic drilling system all controled the brake mechanism to drill,neither using initial controller or computer or PLC controller. So the brake mechanism was worn and torn in intensity. And before the system start up,the conversion of kinetic friction and breakout friction would be having difficulties holding it steady. The automatic drilling system based on profibus and frequency control of motor speed could control the motor-output,keep WOB invarible.And it enhanced the speed of drilling and stability,reduced the drill bit wear.The NCSs (networked control systems)using profibus technologies consist of the brake mechanism,frequency converters,controller,data acquisition system and monitored control system,it raise security and steady of the automatic drilling system.First of all,this paper carried out a theoretical analysis with the old automatic drilling system and pointed out the present problems and the prescription was listed out from.Meantime it put forward the necessity of automatic drilling based on profibus and Frequency control of motor speed technology and then according to the controlling principles of the motor of quadrant logic speed regulation system,it worked out the schematic diagram of frequency control of motor speed,hardware setup and PLC program. |
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