励磁涌流(国外英文资料).docVIP

励磁涌流(国外英文资料) Transformer inrush current Not only lead to transformer inrush current protection misoperation, derived from the power grid voltage sags, harmonic pollution, and over voltage and inrush current, ferromagnetic resonance has negative influence should not be underestimated for power system operation. For decades the people through the identification of inrush current feature method to reduce the relay misoperation rate, but did not gain a good return, the misoperation rate is still high. As for the voltage sag, harmonic pollution and sympathetic inrush and so on, even more helpless. The reason is that people think that the inrush current can not be resisted, and only identification is adopted, that is, the countermeasure of hiding. In fact, the idea of suppressing is entirely possible and has been achieved. The reason: the causes of excitation inrush from inrush current is applied voltage surge in transformer windings on either side felt when the flux conservation theorem based on the generation of unipolar magnetic bias winding in the magnetic circuit, the magnetic pole, such as partial remanent magnetization and the polarity of the original transformer exactly the same, it may be due to bias and remanence and the steady state flux superposition due to magnetic saturation, thereby greatly reducing the excitation reactance of the transformer winding, and then induce considerable numerical inrush current. The danger of inrush current 1.1, the transformer relay protection device misoperation, so that the transformer put into operation frequently failed; 1.2, when the transformer is out of line short-circuit fault, the voltage generated during the removal will lead to transformer protection misoperation, so that all side load of the transformer will be cut off; Inrush current of a transformer load power produced by the 1.3 A power station, B station, C induced by proximity to other power plants running transformer sympathetic (sympathetic inrush) and false t