Research And Application Of Fault Diagnosis For Solar Thermal Utilization System

Global warming,fossil energy depletion and population growth are the common challenges faced by humans in the world.Energy conservation and emission reduction has become a global consensus.As a clean and renewable energy,solar energy is widely used in heating,power generation and seawater desalination.Recently,solar energy play a predominant role in Eco-building and energy saving.With the wide application of solar energy in buildings,the goal of sustainable development and environmental protection could be achieved.Generally,large scaled solar water heating system has a number of operating parameters with complex control strategy being applied,making it difficult to diagnose the faults in operation.At present,there are limited achievements made in the research of solar water heating system fault diagnosis using intelligent fault diagnosis technology.Only traditional diagnostic methods such as experience method,device replacement method and equipment detection method are adopted.Accurately diagnosis the fault occurred in solar thermal utilization system to ensure a reliable operation becomes an urgent problem to be solved.With the development of fault diagnosis theory and computer technology,some advanced fault diagnosis technologies have been successfully applied in aerospace,nuclear energy utilization,weaponry and equipment,biochemical and satellite communications.According to solar water heating system,fault diagnosis expert system based on fault tree was developed to accurately diagnose and locate the faults.The research work mainly includes:1)Thermodynamic cycle and The operation strategy of a solar water heating system were studied.By analyzing the field operating state and data,the faults were identified and classified,the causes of the typical faults of solar thermal utilization system was analyzed in detail.2)Analyze the solar thermal utilization system,adopt fault tree analysis,using typical faults as top events,the fault tree was established to solve the minimal cut set and structural importance.Qualitative and quantitative analysis were carried out to construct expert system knowledge.3)The related theories of rough set were studied,and the algorithm of improving relative attribute reduction and attribute value reduction applied to optimize the rule acquisition of location top events,so that the faults could be located quickly and accurately under the situation of many top events.4)The method of knowledge representation and the design of inference engine were studied.The rule knowledge base was established by production representation,and the inference engine suitable for the system was designed by using the method of forward reasoning and deep traversal.Finally,a fault diagnosis expert system for solar water heating system was established.The fault diagnosis software was developed using Microsoft Visual Studio 2008,and the functions of each module were realized.The software was successfully applied in the system.