This paper proposes a new technique for the simulation of transformer hysteresis loops using the fractal theory. The latter is a fairly new field using a simple process and iterations to model the dynamic phenomena of a complex system. Investigation on the ferromagnetic phenomena of transformers has revealed that fractal features exist, and indeed, the major magnetic loop is very similar to the minor magnetic loops. A new algorithm is developed and a variable compressing factor is introduced, where the minor magnetic loops are formed by using linear-varied factors in compressing the major magnetic loop. Simulation results compared with experimental waveforms have provided that the proposed algorithm is valid in describing the dynamic magnetizing procedure of the ferromagnetic elements in transformer.
The paper proposes two new separation schemes based on the local electrical quantities. The first scheme is called "P-Q sign ' method, which utilizes the active power and reactive power of the tie line to exactly detect the out-of-step in time. The second is modified from the widely used "compensating principle" for separation, which overcome the limit that the settings aren't easy to design. Those two schemes cooperate with each other to supply for the power system separation effectively. At last, the arithmetic is verified by the simulation of two-machine-five-bus system.Index Terms : out of step, system separation * or -na.com) 0-7803-7459-2/02/$17.00 0 2002 IEEE
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