As DGA can not determine the cause and position of the faults, this paper presents an overheating expert system based on the expert knowledge of electrical experiments and infrared temperature measurement. In this expert system: knowledge is modularized, rule is based on basic and compound facts, positive and negative direction mixed inference strategy is used, fuzzy mathematics is applied to realize inaccurate knowledge representation and inference, all these are used to optimized the system function.
This paper first derives the complex coordinate description of voltage and current in α β coordinates,which is very clear in mathematical description and distinct in physical meaning. Based on it,we can conveniently derive the method of detecting the separate negative α β and positive sequence harmonics components and the method of exactly detecting fundamental active power current.
A general expression for the winding coefficient based on the analysis of the winding magnetic force produced by q concentric coils with different turns and unequal pitches of positive or the negative phase belt is represented in this paper.