A new approach for replenishing DC link energy for Interline Dynamic Voltage Restorer to mitigate voltage sag

Power Quality improvement at the distribution level is a demanding requirement these days. The major power quality problems are voltage sag and harmonics. To mitigate the voltage sag, Dynamic Voltage Restorer (DVR) is one of the solutions which involves real power injection into the system which entirely depends on the energy storage capacity of the DVR. This limits the capability of DVR for longer duration of voltage sag. Therefore the DVR in its present form has to be modified and extended to overcome this drawback. The extended device is known as Interline Dynamic Voltage Restorer (IDVR), which consists of two or more DVRs sharing a common DC link. One of the major aspects of IDVR is its controller which modulates the injected voltage to compensate the voltage sag in the system. The other one is being able to replenish energy at DC link for the required compensation. In this paper, a different way of replenishing the energy at the DC link utilizing Phase shifting transformer and differential energy from Photovoltaic system is presented. The simulations are performed using MATLAB SIMULINK software.