Implementation of the diagnosis method DYANA, applied to a combined heat-power device

摘要

The development and implementation of the monitor-and-diagnosis method DYANA is presented. This implementation is applied to and tested on a combined heat and power generating device (CHP). The steps that have been taken in realizing this implementation are evaluated into detail . In chapter two the theory behind DYANA is recapitulated. Attention is paid to the basic theory of diagnoses, and the steps of the path from this theory to the algorithm DYANA are revealed. These steps include the hierarchical approach, and explain the following features of DYANA: a) the use of best-first dynamic model zooming based on heuristics with respect to parsimony of the number of components within the diagnoses, b) the use of consistency of fault models with observations to focus on the most likely diagnoses, and c) the use of online diagnosis: the current set of diagnoses is incrementally updated after a new observation of the system is made. In chapter three the relevant aspects of the system to be diagnosed, the CHP, are dealt with in detail. An explanation is given of the broad working of the CHP, its hierarchical structure and mathematical representation are given, CHP observation is commented, and some possible forms of fault models are stated. In chapter four the pseudocode of the implementation, developed for DYANA, is presented. The pseudocode consists of two parts: the monitoring process (using numerical simulation), and the diagnostic process. The differences between the pseudocode and the actual implementation are mentioned. The CHP will then be monitored and diagnosed with this algorithm and results of this test are given in chapter five. An actual implementation of DYANA can be found in a separately supplied appendix, the Programme Appendix. The implementation of the monitoring process is meant only for this example of the CHP. The code for the diagnostic process can be easily adjusted for diagnosing other devices, such as electronic circuits. The language is Pascal.