Research on interturn short circuit fault location of rotor winding in synchronous electric machines

Abstract

Rotor winding interturn short circuit is the main fault of synchronous electric machines, it is of great significance to the safe and stable operation of the machine to discover and handle the fault timely. In view of this, the fault positioning method of rotor turn-to-turn short circuit of synchronous machines was studied. The mathematic expression of exciting magnetomotive force (e-m.m.f.), electromotiveforce (e.m.f.) and current of stator were deduced. we analyzed the characteristic harmonic of e-m.m.f., stator e.m.f. and current caused by rotor winding interturn short circuit; every harmonic amplitude variation of stator branch current was given in the relationship with rotor turn-to-turn short circuit. The different harmonic variation ratio of stator branch currents is only relevant to the position of the rotor interturn short-circuit coil and has a one-to-one relationship, so the rotor interturn short-circuit positioning method is presented. The method is verified by six-pole non-salient pole synchronous machines.