R&D For Pumping Frequency Energy-saving And Control Technology

At present, beam pumping unit is the most widely used oil field equipment. In practical application, there are many problems, For example,"big horse hauling small cart", high energy-consuming, low efficiency. Besides that, the motor of pumping unit has different levels of regenerating electricity, which further reduces the efficiency of machine. According to the needs of draining oil, the system requires transmission to adjust speed, which has poor flexibility and to some extent reduces the pump efficiency in some pumping unit. In view of this, the paper researches and develops a kind of frequency conversion control system for beam pumping unit in order to save energy and improve efficiency.The system uses AC-DC-AC frequency conversion main circuit with uncontrollable rectifier diode and inverter unit based on IGBT or power integrated modules IPM. The system can realize the automatic switching between frequency and frequency conversion through a complete control circuit of relay contacts which is specially designed. The control system based on dsPIC30F4011 digital signal controller adopts SPWM control technology to achieve motor VVVF. The control system mainly includes DSC control unit, keyboard and display unit which is controlled by STC MCU, detection and protection unit, power module-driving unit, switching power supply and so on. In system's design, DSC and STC microcontroller perform their own function separately and coordinate each other through serial communication. The whole system can achieve soft start and stop of variable frequency. According to the differences of load, it can automatically adjust the control to save energy. According to the needs of draining oil, not only can the system change operating frequency at any time but also achieve different frequency operation between up and down stroke.For the uplift of DC side voltage resulted from regenerating electricity, the equipment has special energy-consuming circuit, while the control system is equipped with the monitor of DC side voltage and the regulator control of motor side. Experiments show that the whole equipment has perfect function, safe and reliable operation, and obvious energy-saving effect.