A study of wavelet entropy theory and its application in power system

AbsIracf-Forecasting the fault and danger in power system and limiting their incidence have been the emphasis in modern power system study. The abundant real-time data gathering in power system contain the complexity and uncertainty of the system, so mining and fusing a series of universal applicable quantities from these datu to detect system fault and its stability is essential. Combining wavelet analysis, the. modern time-frequency analysis technique, with entropy theory by exploiting their virtues will resolve ;the problem. I n this paper, the feasibility of the wavelet entropy applicution in power system fault detection and distinguish is analyzed, the wavelet entropy concept based on wavelet analysis is defined, the computation methods of the two kinds of wavelet entropies are established, and the application of the wavelet entropy in transmission line fault detection is simulated and analyzed. The modem power system has already stepped into high voltage, large power grid and large generator era, the extensive interconnection of the power system and the adoption of numerous new and,high technology, in addition the introduction of the electricity power market mechanism make systematic complexity higher and higher. All these are nowadays the remarkable characteristics of power system. The big electric network has brought potential danger while bringing enormous interests to users. Some partial problems of the electric network can bring out malignant chain reaction and lead to great systematic accident and power failure by a large scale. Measuring various kinds of faults in the power system in time, classifying fault fast and accurately, setting up a high-efficient fault information measuring and classifying online system of power system, are very essential for dealing with the power system fault, even for preventing the calamities and changes of the power system. Power system itself is an open dynamic system, because of the interference of environment to the motive force characteristic of power system, to measure and classify the fault accurately, and to prevent the accident from further development totally is difficult. Therefore drawing and classifying the characteristic of the fault information have already become the focal point and one of the difficult points of electric power system research. Besides complexity and uncertainty of power system , the non-linearity and time-change in systems exist objectively, so calculating and classifying the fault by routine theory based on mathematics model seem unable to do what one wishes. There are two main reasons. On one hand, the accurate mathematics model …