Voltage sag and unbalance mitigation in distribution systems using multi-level UPQC

Unified Power Quality Conditioner (UPQC) is a series-parallel element in the Flexible AC Transmission System (FACTS) family. In this paper, a UPQC with cascaded multilevel inverter is proposed. Voltage sag, unbalance and load power factor in distribution system is mitigated using proposed multilevel UPQC. There is no need of using transformer and filter when multilevel UPQC is applied and it is one of its advantages. SPWM (Sinusoidal Natural Pulse Width Modulation) scheme is used for pulse generation to control multilevel inverters. The results showed the effectiveness of the proposed method.