Based on aerodynamics theories,this paper introduced two different methods for estimation of pressure tightness of EMUs:time constant and equivalent leakage area.

Research and experiment verification of influence of magnetic isolated segment on leakage reactance in submersible motor;

Analysis of replacing balancing reactor for parallel rectifiers with leakage reactance transformer;

Both theoretical analysis and simulation prove that rationally designed leakage reactance of the primary winding can play a role of balancing reactor.

Presently in transformer model,it is considered mainly whether the equivalent impedance is assigned to the side of normal ratio,but seldom whether the equivalent impedance is on the side of on-load tap changer.

To research the accuracy of the load model and its parameters being adopted in the dispatching department of central China power grid to guide the load modeling scientifically, the equivalent impedances of distribution networks of central China power grid are calculated by power system analysis software package (PSASP).

In off-line power flow studies, as the equivalent impedance of a transformer is directly given, it is not necessary to consider the effect of tap changer regulation on the impedance of a transformer when a transformer model is selected.