Design And Study On Sequence Of Events Record System Based On Virtual Instrument Technique

With the increasing scale and complexity of thermal power units, the information is ever-changing in the producing process. When the units are in failure, how to correctly and quickly identify the first accident-induced failure, as well as all related equipment action sequence, will be related to dealing with the accident promptly or not and resuming normal operation of the system. Therefore, the sequence of events recording device (SOE) has become a main analyzing method of the accident. While most of the SOE system is established in large-scale DCS or the monitor system composed by PLC. As for small-scale heat-engine plant, low-cost SOE system is lacking. Nowadays, most of the SOE system can only reached milliseconds of the resolution. When some event happened, more information would appear at a very short space of time and the sequence cannot be resolved. And the monitoring terminals of SOE system is generally less, only covering the most important switching units in the operational power plant, which makes the accident analysis disturbed. This thesis focuses on the supervisor's cross research project, develops a set of SOE system for small-scale heat-engine plant. The system can achieve data acquisition for 500 switching units with 0.5ms resolution, and offers an economical resolution to small-scale heat-engine plant.Based on the actual test requirements, an overall plan of SOE system is formulated: The test system composed by enhanced 51 MCU and PC based on virtual instrument technique realized the separation of data acquisition and processing functions. The part of MCU mainly contains the choice of sampling CPU and the design of external circuit units, input channels, the data exchange interface between sampling CPU and communication CPU; the choice of communications port and the design of communications software. The upper computer chiefly makes use of virtual instrument technology, it is developed on LabVIEW platform, and realizes the design of human-computer interface and the compilation of functional modules software, including functional modules of the serial communication design, channel parameters configuration, data storage, and the report program generation.Finally, the system is verified through the self-made SOE supply oscillator. The results show that the system can achieve data acquisition of 500 switching units with 0.5ms resolution. From the experimental results, it can be seen that the system can actually record the state changes of switching units, which can provide a reliable basis for the further study of failure analysis in power sector and other related industries.