游梁式抽油机电动机断续供电节能技术断电时刻准确判定方法

Power-off Time Precise Determination of Intermittent Power Supply Technology for Beam Pumping Motor Systems

＂断续供电＂技术应用于油田机采系统,能够获得明显节能效果,如果断电时判定不合理,不仅影响节能效果还会使得转速超限,损坏机械结构并导致停机。因此,如何准确判定断电时刻便成为面临的首要问题。该文提出一种基于断电后系统转速预判的断电时刻准确判定方法,该方法通过分析抽油机平衡配重与曲柄位置、悬点及泵载荷与其位移之间的关系,揭示在电机在通、断电两种状态下负载转矩随曲柄旋转角度的变化规律,建立由曲柄角度表示的通、断电过程中的负载转矩表达方程;进而通过输入端可测电气量预先计算出断电后随曲柄旋转角度变化的负载转矩和转速曲线,实现了最佳断电时刻准确判定。基于该方法研制的控制器应用于油田,节电率可达15%以上。

＂Intermittent power supply＂ technology can achieve significant energy saving effects for Beam Pumping Motors（BPMs） in oil field. However, unreasonable power-off time not only affects the energy saving effect, but also causes the speed of beam pumping units to exceed the limit, which may compromise the operation safety and damage or break down the system under severe conditions. Therefore, the most important issue is to accurately determine the power-off time in practice. This paper proposed the accurate power-off time determination method based on speed prediction after power-off control. Through analyzing the relationship between the balance counter and the crank position, as well as, load of the polished rod and pumping, and its movement, the characteristic of load torque varying with crank angles was firstly revealed, and the load torque equations in terms of crank angles was established during power-off and power-on operations. Then, the load torque and speed curves after the power-off control can be predicted by using the measured electrical quantities, and the optimal power-off time can also be determined directly. The energy-saving controller was developed and applied to oil fields, which saves electric energy by over 15%.