Optimizing the Running Parameters of a Variable Frequency Beam Pumping System and Simulating Its Dynamic Behaviors

The simulation models of the crank movement and the sucker rod string longitudinal vibration are setup by considering the influence of real time variation power frequency and motor load torque fluctuation to transient rotating speed of the motor shaft, and the simulating models of dynamic parameters, that contain the polished rod load, the crank net torque, the output power of the motor and its input power, are established. These variables, which contain the suction parameters, balancing device parameters, frequency function and rotary inertia of motor output shaft belt pulley, taken as optimization design variables; and these conditions, which contain unchanged oil well output, the bearing load capacity of the pumping unit, the rod string strength, the balancing scale and the ratio of the up-stroke period and the down-stroke period, taken as the constraint conditions; and minimizing system input power taken as the optimization design objective function, a mathematical model of integrated optimization design of the variable frequency beam pumping system is built. Simulating and optimizing results show that: 1 under the condition of given suction parameters, optimizing real-time frequency can improve the dynamic performance of a beam pumping system and reduce its input power; 2 optimizing rotating inertia of belt wheel of the motor output shaft can be appropriate to reduce the output power amplitude and the input power of the motor; 3 comprehensively optimizing suction parameters, balancing device parameters, frequency function and motor output shaft moment of inertia can observably improve the dynamic performance of the system and reduce the system input power.