Article Information
Feed-Forward Control Strategy for the VSC of DVR for Smooth and Clean Power Flow to Load

Keywords: Power Flow, VSC, Custom Power Devices, Unipolar SPWM Control Law, Power Quality, Sensitive Load, Dispersed Generation.

Mehran University Research Journal of Engineering & Technology

Volume 31 ,  Issue 2

Aamir  Hanif,Mohammad Ahmed Choudhry,Tahir  Mehmood

Abstract

VSC (Voltage Source Converter) feed-forward control strategy of DVR (Dynamic Voltage Restorer) for an in-phase voltage injection scheme is proposed in this paper to tackle not only voltage sags and swells in the utility supply but also phase jumps as well. The proposed strategy utilizes a time based ramp at a clock rate of 50Hz to obtain a 3-phase reference signal that is compared with actual 3-phase utility voltage to obtain an error signal. If the error in each phase of the utility voltage is greater than zero then appropriate control signals are generated. The switching devices in VSC are switched accordingly to compensate voltage sags, swells and phase jumps in the utility voltage that propagates to load. For the mitigation of voltage sags, swells and phase jumps, the unipolar SPWM control is used. The proposed control system response time to compensate voltage sag, swell and phase jump through switching of VSC devices is less than 10ms whereas ITIC curve and SEMI-F-47 standard suggest a target of 20ms. Load voltage THD is below 5% as per IEEE Std. 519-1992. These results show that employed control strategy has an excellent capability of voltage restoration with acceptable harmonic distortion, within specified time frame for smooth and clean power flow to load. MATLAB�/Simulink� SimpowerSystem tool box has been used to obtain simulation results to verify the effectiveness and validity of the proposed control strategy to improve the quality of the power delivered to the load.