Overload prevention

This work presents a series active filter system for three-phase, four-wire distribution systems to alleviate the overloading of the neutral conductor. The active filter system employs a voltage sources inverter connected in series with a neutral conductor to suppress the excessive current harmonics. Theoretical analysis shows that series active filter system are more suitable than shunt active filter systems because most of the nonlinear load at low voltage levels are categorized as harmonic voltage source type. Laboratory test results show that the proposed system achieves desired filtering function.