Modeling and simulation of substation fault diagnosis based on Petri nets
In order to improve the efficiency of the substation fault diagnosis with multiple protections, the proposed method describes protection grades by varied weight of the transition vector in the Petri net models. According to relays and circuit breakers, special markings are produced in the diagnosis results that enhance the identifying capability of error information. The process of fault diagnosis is accomplished by algebra matrix calculation. A simulation on actual substation fault diagnosis process indicates that the improved method has fast calculation speed and high veracity
APPLICATION OF PETRI NETS IN TRANSFORMER FAULT DIAGNOSIS
The Petri nets theory which takes the net theory and algebra theory for mathematical basis can be used to describe the various relations and behaviors in the discrete event dynamic system by graphical means. Because the Petri nets is suited to describe the computer system model under the asynchronous concurrent phenomena and to make the behavior analysis on parallel and concurrent system, so it is more and more widely applied in artificial intelligence field. In this paper a fault diagnosis model for power transformer based on Petri nets is proposed in which by use of Petri nets the matrix operation algorithm for knowledge representation and inference is dissertated, the relation between the fault omen and the fault itself is described. The presented model is simple and clear, in which only simple matrix calculation based on Petri nets theory is used. Thus, the time for fault diagnosis can be obviously reduced and the diagnosis accuracy is improved. Testing the presented model by practical examples, the results show that this model is fast and accurate.
Prediction of a representative point for rail temperature measurement by considering longitudinal deformation
Monitoring rail temperature is very important for determining the safe running speed of trains and to prevent buckling. In general, the maximum variation of the internal rail temperature can be >7 ℃ depending on the point of measurement. However, there is as yet no sufficient information about how to predict the measurement point to represent the thermal deformation due to temperature distribution. In this study, the authors report a new point, called the representative measurement point, at which the rail temperature can be measured. This point considers the average deformation of the rail through structural analysis by adopting experimental and actual rail temperature data. The authors designed and installed a measurement system similar to an actual rail environment. Using the system, various data were acquired (internal/surface rail temperature and weather data) for 10 months. On the basis of these data, an analysis was done to calculate the average deformation point through thermal analysis. Finally, the representative measurement point was proposed as the position at which the average deformation point converges regardless of weather or seasons. The authors believe that the method described herein is advantageous in that it could be used in a high-accuracy temperature-monitoring system and for predicting thermal deformation and buckling.