针对变频控制游梁式抽油系统,考虑了频率实时变化对抽油机运动规律、杆柱纵向振动、悬点载荷、地面装置节点扭矩与功率的影响,建立了变频控制游梁式抽油系统动态参数的仿真模型。对实时频率函数进行傅里叶变换,并以其傅里叶系数为设计变量,以电动机输出功率的均方根值最小为优化设计的目标函数,综合考虑冲次不变、上下冲程时间分配、频率范围等约束条件,建立了实时频率优化设计的数学模型。仿真与优化结果表明:所建立的仿真模型具有较高的仿真精度,能够满足实际应用的要求;优化实时频率可以显著改善抽油机的动力性能,悬点载荷波动幅度降低,曲柄轴最大扭矩与扭矩波动幅度显著下降,电动机输出功率幅值与波动幅度显著下降,降低了系统输入功率,有功节电率为25.8%。
A dynamic parameter simulation model of beam pumping system with frequency conversion control was established,considering effects of real time frequency variation on motion law of suspension points,longitudinal vibrations of sucker rod,polished rod loads,ground device node torques and powers.By transforming the real time frequency function into the Fourier series,and taking the Fourier coefficients as design variables,an optimization mathematical models of the real time frequency function was setup,where the minimum root mean square of motor output power was taken as optimization objective function,and some constraints were considered,including constant strokes per minute,the ratio between the upstroke time and down stroke time,and real time frequency varies within the given bounds.Simulation and optimization results show that:simulation accuracy is high and can meet the demands of project applications;dynamics performance of beam pumping unit is improved significantly after real time frequency optimization,suspension point load fluctuation is reduced,maximum torque of crank shaft and torque fluctuation amplitudes are reduced significantly,motor output power amplitudes and fluctuation are reduced significantly and power utilization is improved,active power saving rate is as 25.8%.