基于形状上下文匹配方法的有杆抽油系统故障诊断

Fault diagnosis of sucker rod pumping system based on matching method of shape context

关键词:  抽油井泵功图  形状上下文  灰度理论  回溯法  最小对比度

Key words:  pumping dynamometer diagram of pumping well  shape context  grey theory  backtracking  minimum contrast

摘要:

针对复杂的井下工况,全面而有效地提取泵功图的细节信息在有杆抽油系统的故障诊断中至关重要。提出基于形状上下文匹配方法来诊断抽油泵的故障。通过抽油杆柱的波动方程将抽油机悬点示功图转化为泵功图;采集泵功图的轮廓点,并利用形状上下文对轮廓点进行描述。计算待诊断泵功图和故障泵功图之间任意两点的匹配代价值,获得代价矩阵。采用回溯法在代价矩阵中搜索最优匹配点集,获得泵功图的匹配代价值,进而诊断出抽油泵的故障类型。结果表明:新方法的诊断结果与实际情况相同,验证了本文中方法的有效性;基于形状上下文匹配方法的匹配代价值的最小对比度明显增大,可以提高故障诊断结果的可靠性。

Abstract:

Faced with the increasingly complex downhole conditions, it is very important to extract the detailed information of pumping dynamometer diagram comprehensively and effectively during the fault diagnosis process of sucker rod pumping system. A matching method based on the shape context has been proposed to diagnose the fault of the oil pump. Through the wave equation of the sucker rod, the polished rod dynamometer diagram was converted to the pumping dynamometer diagram. The contour points of the pumping dynamometer diagram were collected and described by the shape context. The matching cost value of two arbitrary points between the diagnostic pumping dynamometer diagram and the fault diagram was calculated to acquire the cost matrix. The backtracking method was used to search the optimal matching point set in the cost matrix, and the matching cost value between the pumping dynamometer diagrams was obtained.Then the fault types of pumps were diagnosed. The results show that, the diagnostic results of this new method are the same as the actual situation, which verifies the effectiveness of the method. Compared with the matching method based on gray level theory, it is found that the minimum contrast of matching cost value based on the shape context matching method increases significantly. Therefore, the algorithm improves the reliability of the diagnosis results.