Study Of High-efficiency Saving Energy Control System For Beam-balanced Pumping Unit

Beam-Pumping Units is the main equipment and energy consumer in recover petroleum. Under the normal operation condition, the average load ratio of the oil-pumping motor is usually less than 30% of the rated value. This circumstance causes the coefficient of utilization of the electrical machinery and increase the electric power loss. In order to solve this problem, this paper develops a High-efficiency Saving Energy Control System for Beam-balanced Pumping Unit.This paper introduces the present internal and external situation of using the Beam-Pumping Units and analyses the working way of it. Then the paper discusses the cause of low efficiency of the Beam-Pumping Units. On the basis, by comparing different measures of saving energy that have been used in oil fields and pumping machine characteristics, a new saving energy scheme of VVVF and power factor loop control is proposed in this thesis.The controller of the Beam-Pumping Units is based on the AT89C51 single chip micro-computer. The hardware part is made of main circuit, drive circuit, control circuit, protection circuit, power factor and energy regeneration circuit etc. Main circuit adopts the structure of AC-DC-AC voltage source type. The main switch component uses IGBT power module. Control circuit selects pulse width modulation chip SA866AE that can generate SPWM control signal. The single chip micro-compute control part is composed of display circuit, keyboard circuit, reset circuit, memory circuit, power factor detection circuit and frequence output circuit etc. The IGBT drive circuit uses the special-purpose EXB841 module to carry on the amplification of control signal. Protection circuit includes over-voltage protection, over-current protection, short-circuit protection. The software part comprise the initialization parameters designs of SA866AE's EEPROM, the program of micro controlled unit and the program of motor soft start. The software programmed with the compilation language.Finally, the paper gives out some results of the experiment. The developed system applied in Shengli oilfield showed the power factor of AC asynchronous motor of up to 0.98 at the best and its energy-saving result of total efficiency are by 28.4%, exhibited a good effect on energy saving.