Simulation Study On Fault Detection And Diagnosis Of Variable Air Volume Air Conditioning System Based On TRNSYS

Energy-saving operation of air conditioning(AC)systems plays a significant role in reducing building energy consumption,while the fault detection and diagnosis(FDD)is crucial to energy-saving optimal control and stable operation of AC systems.This paper proposed a novel active FDD method based on a series of engineering problems,such as large-scale of VAV AC systems,complexity of control strategy,frequent fault occurrence of various types,lack of sensors and insufficient of diagnostic information.This method could further diagnose the faults which are unable to be separated by traditional passive FDD method by means of introducing small disturbance to the system.This method is comprehensive,convenient and high-efficiency,which is suitable for FDD in large-scale AC systems.The following works have been done in this paper based on the proposed novel active FDD method:(1)Firstly,a typical VAV AC system consisting of a single air duct,primary return air and dual fans was established by using TRNSYS as the simulation platform in this paper.Component models such as fans,sensors,VAV terminals and so on were also established.The system resistance equilibrium equations based on Kirchhoff's law were calculated by Engineering Equation Solver(EES).The established system is able to simulate the operation process of multi-area VAV AC systems,and provide a platform support for the development of FDD method eventually.(2)Secondly,the feasibility of the system was verified by simulating the normal operation and introducing the common faults in AHU and VAV-boxes.A comparative research was carried out under normal and fault occurrence operation conditions to analyze the changes in characteristics,such as system measured values,energy consumption,PMV values and so on.The results showed that the established system could be used for further FDD.(3)Finally,a novel passive and proactive combined FDD method of VAV AC systems was presented in this paper.The method was applied to 21 kinds of common faults in VAV terminals.This paper proposed 5 kinds of passive diagnosis classification rules according to these faults.The corresponding proactive diagnosis rules were formulated based on different passive diagnosis classification rules.The feasibility of this method was verified by the utilization of the established TRNSYS simulation platform.The results showed that the method could effectively diagnosis the common hardware faults in pressure-independent VAV terminals,such as the jammed dampers,deviation of sensors and so on.