Liquid Supply Analysis And Stroke Frequency Auto-Control Of Beam-Pumping Unit

With the rapid development of the national economy, oil as a strategic resource has been paid more and more attention. China’s stratum energy is lower than Middle East, after a period of exploitation, liquid supply shortage is widespread emergence. Liquid supply shortage can cause the rod pumping system oil discharge reduction, system pump efficiency decreased and energy waste. Rod pumping system pump efficiency can be improved by regulating stroke frequency with liquid supply condition.Firstly, the working principle of rod pumping system and indicator diagram was analyzed, design indicator diagram load signal acquisition circuit. In order to verify its effectiveness, the indicator diagram load signal acquisition circuit is simulated. The derivation method of pump indicator diagram was researched, the relationship between the valve opening-closing position and effective stroke in pump indicator diagram was analyzed. The curvature change rate of pump indicator diagram was calculated by five point curvature method. The effective stroke of the plunger is determined, and the pump efficiency of the rod pumping system is calculated.Secondly, In view of the problem of liquid supply shortage, the pump efficiency control strategy of rod pumping system was researched. The coordinate transformation principle of vector control and mathematical model of asynchronous motor is analyzed, the vector control system of asynchronous motor based on voltage space vector(SVPWM) is established. By control the speed of beem-pumping unit, the stroke frequency of rod pumping system is matched with the liquid state of the oil well, achieve the purpose of improving the pump efficiency. The simulation model of asynchronous motor vector control system based on SVPWM was built by Matlab/Simulink, the effectiveness of vector control system is verified by simulation.Finally, set up experimental platform of indicator diagram load signal acquisition circuit, design experiment program, according to a large number of experimental data, the effectiveness of acquisition circuit is verified. Set up experimental platform of the pump efficiency control system, design experiment program, according to a large number of experimental data, the pumping efficiency of rod pumping system was compared after the experiment, the effectiveness of pump efficiency control system is verified.