Effects of DC-Current for Short-Time Negative Sequence Current of Synchronous Machine

Abstract

When a line-to-lire short-circuit occurs, the positive-sequence-, the negative-sequence-and the DC-current flow in the armature winding of synchronous machine. The negative-sequence current is limited in JEC-114, as this current causes the induced current and the overheat on the surface of the rotor. The DC- current causes also the overheat on the surface of the rotor in a similar reason. This paper proposes the calculation method for the equivalent short-time negative sequence current considering both of the negative-sequence current and the DC-current.