基于RVM回归的姿控系统多故障检测

针对卫星姿控系统故障具有并发性和多发性的特点,敏感器和执行机构均可能发生故障,依据相关向量机(RVM)回归理论,采用基于模型辩识,残差评价的方法实现姿控系统多故障检测.通过对太阳敏感器、陀螺和反作用轮的历史输入输出数据建立RVM回归模型,考虑到建模精确度直接影响到检测精确度,对比分析最小二乘支持向量机回归( LSSVR...     

一种改进的马氏距离相对变换主元分析方法及其故障检测应用

目前, 主元分析方法(PCA)在数据处理、模式识别、过程监测等领域得到了越来越广泛的应用, 但仍存在部分关键问题亟待解决. 本文为了提高PCA方法的故障检测性能, 进行了一系列的改进, 首先, 本文引入相对变换的概念, 使用马氏距离相对变换直接消除量纲, 通过理论推导证明了马氏距离相对变换可以对数据不进行标准化直接进行数据变换, 而且给出了在相对空间内数据进行PCA变换的合理解释, 表明了基于马氏距离相对变换的PCA故障检测方法可以有效的消除变量量纲对数据的影响, 提高数据的可分性. 其次, 改进了SPE监控指标, 提出一种基于马氏距离的平方预测误差指标, 更有效地实现对工业过程的故障检测. 最后, 将两种改进方法相结合, 提出改进的马氏距离相对变换PCA故障检测方法, 并以轧钢过程活套系统为背景, 实际数据仿真结果表明: 与PCA以及其它改进方法相比, 本文提出的方法具有更好的故障检测性能和实时性, 能准确、有效地检测出活套故障.     

A multi-fault diagnosis method based on improved SMOTE for class-imbalanced data

With the development of industrial processes, how to effectively diagnose the faults in an increasingly complex production process has attracted widespread attention. It is worth noting that there may be multiple types of faults in the actual industrial process, and there is an extreme class imbalance between the normal samples and the fault samples. Therefore, it is of practical significance to carry out research on the multi-fault diagnosis method for class-imbalanced data. In this paper, a multi-fault diagnosis method based on improved synthetic minority sampling technology (SMOTE) is proposed. First, aiming at the class imbalance, an improved SMOTE algorithm based on Mahalanobis distance (Mahalanobis distance-based SMOTE [MSMOTE]) is proposed for oversampling. As the Euclidean distance in the traditional SMOTE algorithm does not consider the coupling relationship between features, the Mahalanobis distance is introduced, which is not dependent on the scale and eliminates the influence of different dimensions. Second, in order to better obtain the global and local information of the sample, the kernel local Fisher discriminant analysis (KLFDA) algorithm is used for feature extraction. Third, a multi-fault diagnosis model based on the AdaBoost.M2 classifier is constructed in which the decision tree is introduced as the weak classifier. The Adaboost.M2 algorithm integrates multiple decision trees by setting the sample weight, the label weight, and the classifier weight, which effectively improve the classification accuracy by only using the decision tree. Finally, the Tennessee Eastman process is used to conduct case studies. For the comparison results, the proposed multi-fault diagnosis method based on improved SMOTE has higher accuracy and F1-Score.     

考虑多重故障的热稳关键断面在线识别方法

受限于内外部环境影响,电网发生多重故障的概率增加,离线计算确定的关键断面在网架结构受到严重破坏时无法准确反映故障后电网的薄弱环节.为此,提出一种考虑多重故障的热稳关键断面在线识别方法.首先通过故障前后支路负载率变化量和潮流方向一致性判别,识别出故障潮流转移通道.然后依据不同故障的潮流转移特征,建立基于开断分布因子的故障...