Experiment Researches of Power Equilibrium Technology for Beam Pumping Unit

A new technology of power equilibrium control is put forward to figure out these problems of beam pumping unit under a constant speed, such as large load fluctuation range, big vibration and poor dynamic performance. The basic principle is that the motor rotation speed is changed in real-time according to the changes to the polished rod load within each stroke—so the larger the polished rod load is the slower the motor speed is, and the lighter the polished rod load is the faster the motor speed is. Making the most of the inertia force decreases the fluctuation of the peak power of the primer motor in a stroke. For the purpose of optimizing the motor speed, a power equilibrium control system is designed, which is tested in standard testing well with different parameters to verify its actual applicative effects. The experimental test indicated that, under the same condition, the crankshaft torque and gearbox vibration have an enormously decrease after used the control system. The results of field test about 118 wells show that the average peak power of prime motor dramatically decreases 43.6%, system efficiency boosts 4.14%, the single well can save 23.92 kW·h in each day, and the average energy-saving rate ran up to 16.3%. This new control technology decreases the fluctuation of both the peak output torque and the peak power of the primer motor and can significantly ensure the beam pumping unit system runs smoothly and efficiently.