煤层气井抽水机电动机变频-恒频分段节能控制策略

Segmented energy-saving control strategy based on variable-constant frequency of beam pump motor for CBM wells

由于煤层气井抽水机电动机负荷的动态交变特性,导致抽水机电动机周期性运行于电动和发电状态,造成电能严重浪费。为解决这一问题,结合抽水机负载及悬点运动规律,提出一种基于变频器变频-恒频分段协调工作的抽水机电动机节能控制新策略。该控制策略取消了抽水机按上下冲程划分运行区间的做法,将运行区间重新划分为变频段和恒频段;在变频段改变抽水机电动机工作频率,将抽水机负荷端势能转化为动能,抽水机依靠自身能量转化运行,电动机不做功;在恒频段电动机工作于电动状态,驱动抽水机工作,此时电能转化为机械能。在现场以一台YVP180L-8,11 k W感应电机及其驱动的CYJY4-1.5-9 HB型煤层气井抽水机作为试验平台,对变频、恒频以及提出的变频-恒频分段节能控制策略进行综合节能情况对比。现场实测结果表明:所提控制策略会使抽水机运动和负荷特性发生改变;同时该控制策略能够有效解决能量回馈问题,避免能量回馈电机,较其他两种控制策略系统节电率提高10%;该控制策略具有较强通用性,为煤层气抽采系统节能降耗提供了新的研究思路和角度。

The load of beam pump motor（ BPM） used in coal bed methane（ CBM） wells is dynamically alternated,which results in BPM periodically runs on electric and power status and then results in a serious waste of energy. To solve this problem,combining with beam pump load characteristics and polished rod motion law,a segmented energysaving control strategy based on the variable and constant frequency of BPM for CBM wells is proposed. This control strategy reclassifies the operating range into variable frequency（ VF） stage and constant frequency（ CF） stage instead of up and down strokes divided by the traditional principle. On VF stage,beam pump runs on its own energy transformation by converting potential energy on the load side into kinetic energy resulting from changing the operating frequency of BPM. On CF stage,BPM works on motor status and drives beam pump when electrical energy converts into mechanical energy. Taking a CYJY4-1. 5-9HB beam pump driven by an YVP180L-8,11 k W induction motor as atest platform,the comparative analysis of energy-saving effect of VF,CF and the proposed segmented control strategy based on variable and constant frequency is carried out. Field test results show that the proposed strategy makes beam pump motion and load characteristics change. Meanwhile,the control strategy can effectively solve the energy feedback and avoid the energy flowing through BPM,resulting in the system saving rate improvement by 10% compared with other two control strategies. Furthermore,the control strategy has a strong versatility,thus providing CBM extraction system energy saving a new research alternative.