Advanced Alarm Monitoring Based on Alarm Data

• Author / Creator

  Hu, Wenkai

• Alarm systems are critical assets of modern industrial plants to assist operators in managing plant upsets and hazardous situations. A good alarm system must detect abnormalities and warn the operators promptly and yet at the same time not mislead, overload or distract the operators. However, in many actual cases, alarm systems often function poorly, and distract and overload operators due to nuisance alarms and alarm floods. Consequently, operators might be confounded by these problems, and be less alert to true alarms. To ensure process safety and improve efficiency of alarm systems, this thesis focuses on the development of advanced alarm management techniques, specifically using alarm data. Four problems have been solved. First, a new method is developed to detect and quantify correlated alarms in the presence of occurrence delays, which are identified as the main causes leading to erroneous conclusions from existing methods. The effectiveness of the method is ensured by a statistical test based on the distribution of occurrence delays and a signal conversion mechanism of generating continuous-valued pseudo alarm sequences. Second, in order to assist prediction of alarm floods and prevention of their negative consequences, an accelerated local alignment method is proposed to find similar alarm flood sequences, which are very likely caused by the same root cause. To improve the computational efficiency and accuracy, three novel strategies are incorporated, including the priority-based similarity scoring strategy, the set-based pre-matching mechanism, and the modified seeding-extending steps. Third, to identify abnormality propagation paths and detect root causes, a causality inference method based on binary-valued alarm data is developed as an alternative in the absence of process data. A modified transfer entropy (TE) and a direct transfer entropy (DTE) are formulated based on the two characteristics of alarm signals, namely, the random occurrence delays and the mutual independence of alarm occurrences. Lastly, a data-driven technique is proposed to discover association rules of mode-dependent alarms from historical Alarm & Event (A&E) logs. The proposed method can help process engineers in discovering consequential nuisance alarms, and configuring state-based alarming strategies. The effectiveness and applicability of the proposed methods are validated by case studies using real industrial alarm data. Using the proposed methods, interesting patterns can be extracted from the alarm data, and used to improve alarm monitoring by reducing nuisance alarms, addressing alarm floods, and tracking the propagation of abnormalities.

• Subjects / Keywords

  • Process safety
  • Alarm floods
  • Alarm monitoring
  • Causality inference
  • Alarm system
  • Correlated alarms
  • Mode-depedent alarms

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3HH6CB4X

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.