Usually, the size of neutral conductor is similar as phase conductors but in new commercial installation, larger cross section area of neutral conductor has preferred to take account of extra triplen harmonics current . But use of larger size neutral conductor increase cost, size and significant increase in copper and aluminum requirement .
It is mainly consists of third harmonics currents. The unbalanced single-phase loads result in high neutral current -. The excessive neutral current consisting of both fundamental and harmonic frequency creates over loading of the neutral conductor leading to bursting of it -.
The application of a zig-zag transformer for reduction of the neutral current is advantageous due to passive compensation, rugged and less complex over the active compensation techniques -. A new topology of DSTATCOM is proposed in which a two-leg VSC along with a star/delta transformer.
Neutral Current Compensation The neutral current compensation techniques includes zig-zag transformer, a star/delta transformer, T-connected transformer, Scott-transformer, star-hexagon transformer and star-polygon transformer ,.
All triplen odd harmonics are additive in nature, thus resulting in excessive current in neutral. So the neutral current is blend of harmonics zero sequence and fundamental zero sequence current which is to be mitigate from the system, . The power quality aspects governed by the standards such as the IEEE-519 , . It estimated that
The excessive neutral current consisting of both fundamental and harmonic frequency creates over loading of the neutral conductor leading to bursting of it -. The power quality problems rise due to different types of non-linear loads and expansion of the distribution system without much planning , .