Se-Wan Choi, Minsoo Jang, “Performance Improvement of an Active Neutral Harmonic Suppressor System Under Unbalanced Load Conditions”
Abstract : Three-phase four-wire electrical distribution systems are widely employed in manufacturing plants, commercial and residential buildings. Due to the nonlinear loads connected tot the distribution system, the neutral conductor carries excessive harmonic currents even under balanced loading since the triple n harmonics in phase currents do not cancel each other. This may result in wring failure of the neutral conductor and overloading of the distribution transformer. In response to these concerns, a cost-effective neutral current harmonic suppressor system has been proposed.
This paper proposes an improved control method for the harmonic suppressor system under unbalanced load conditions. The proposed control method compensates for only the harmonic components in the neutral conductor, and the zero-sequence fundamental component due to unbalanced loading is prevented from flowing through the harmonic suppressor system. This remedies overloading and power loss of the system. The experimental results on a prototype validate the proposed control approach.
Keywords : Active filter, Neutral current, Three-phase four-wire, Zero-sequence harmonics