Phase Shifting Transformer based Interline Dynamic Voltage Restorer to Mitigate Voltage Sag

This paper proposes Interline Dynamic Voltage Restorer (IDVR) to mitigate voltage sag, while its DC link energy is restored by phase shifting transformers. The Dynamic Voltage Restorer (DVR) was proposed as a solution to Voltage Sag compensation involving considerable amount of real power injection into the system which entirely depends on the energy storage capacity of DVR thus limiting its capabilities. The extension of the Dynamic Voltage Restorer leads to the concept of IDVR which consists of two DVRs sharing a common DC link. Usually one of the DVR's of IDVR compensates voltage sag while other DVR replenish the energy at DC link. In this paper a new concept of IDVR is proposed where one DVR compensates the Voltage Sag while the energy at the DC link is replenished by other DVR using the phase shifting transformers. The concept is simulated in MATLAB Simulink and performance of IDVR is investigated. Simulation results presented for a three phase example system with voltage sag demonstrates the effectiveness of the proposed method.