Study On Fault Diagnosis Technology About Chilly Water Set Of Single Screw Based On Wavelet Packet Analysis

With the increase of the performance of HVAC plants, the refrigeration system get more and more complicated than before. As a result, it demands more ability in the system's trouble shooting system, the traditional trouble shooting method is no longer met the actual needs. In order to solve this problem, this paper analyzes the fault diagnosis method for chillers using wavelet packet analysis.This paper simulated 9 faults including decreasing of cooling water flow, decreasing of refrigerant and non-condense gas existed and so on. It also analyzed the fault diagnosis technology combined theory and experiments. First, this paper provides the background of this subject, briefly gives an introduction of the research problems and the current development for the HVAC fault diagnosis. Chapter 2 sums up 9 typical faults which have significant influence to the system's parameters through theory analysis of the experiments. Then, it introduces the main contents of the signal handing for chillers, such as signal picking and signal pre-handing. Chapter 4 and 5 makes a description of the establishment of the experimental bench, analyzes the experimental results and draws the experimental chart. At last, after an illustration of the wavelet packet theory, this paper analyzed the experimental data using wavelet packet transform method.This paper founded a fault diagnosis method using random signal Norm. Through extracting a number of feature Norm and tolerance, we can carry out reliability test to the specific sample and category the faults. Considering the accurate and punctuality of the experiment, this paper finally chose the inhaling temperature and exhausting temperature as the feature parameters, established'feature vector-system state'corresponding relationship. Finally, composed fault diagnosis software on the basis of summarizing the fault detection regulations. Using this software, we can find the faults and the state of the chillers quickly and conveniently.Because of the limits of the experiments, there are some problems in this paper, but the fault diagnosis software based on wavelet packet transform can be referenced for others.