New passive filter design for neutral current cancellation in balanced 3-phase 4-wire non-linear distribution systems

Different types of non-linear loads are expected to proliferate into the distribution system, causing the harmonic distortion levels on these systems to increase. Third harmonic and all other triplen harmonic currents have little diversity among different loads and add in the neutral. The neutral current in a low voltage three-phase four-wire distribution system is expected to increase resulting in significant problems. The factors that affect the neutral current magnitude as well as the phase currents distortion are investigated. A new technique, namely, reactance one-port compensator is presented in order to cancel the neutral current and improve the overall system distortion levels. The attenuation and diversity effects are considered during performing this study. The analysis uses the electromagnetic transient program (EMTP) to model the loads as well as the overall system. The proposed filter drastically improves the system performance and substantially reduces the neutral current.