Compensation for neutral current harmonics in a three-phase four-wire system by a synchronous machine

This paper presents a new method that passively reduces the neutral current harmonics in a three-phase four-wire system by a synchronous machine. Selecting 2/3 as the coil pitch of the armature winding can minimize the zero-sequence reactance of the synchronous machine. The proposed method utilizes such a characteristic, which allows harmonic compensation by the synchronous machine. For analysis and design, an equivalent circuit for the third harmonic component of the basic system is derived. Using this equivalent circuit, its harmonic compensation characteristics are theoretically analyzed, and design fundamentals are provided. Experimental results demonstrate the effectiveness of the proposed method and validate the theoretical analysis