Design of Novel Approach to Mitigate Voltage Sag Caused by Starting an Induction Motor Using Dynamic Voltage Restorer

In this paper, a new control strategy for dynamic voltage restorer (DVR) is presented to compensate effectively voltage sags. In this strategy, load and supply voltage magnitude and angle are estimated by least error square filters in short time. The advantage of this method is reducing noise, distortion, and harmonic on estimation parameters. Accordingly, these parameters are controlled for each phase separately. Also, it should be noted that due to the phase angle estimation by LES filters, the control system does not require phase-locked Loop and this issue causes an increase in speed of control system response. In addition, a P+Resonant and Posicast controller are used to eliminate the steady-state error and improve transient response in DVR, respectively. The proposed control system is simulated, using PSCAD/EMTDC software by induction motors starting is connected to 13 bus IEEE standard network. Finally, the simulation results prove that the proposed control scheme performs satisfactorily under sudden changes of load.