Voltage sag and swell compensation with DVR based on asymmetrical cascade multicell converter

This paper deals with a dynamic voltage restorer (DVR) as a solution to compensate the voltage sags and swells and to protect sensitive loads. In order to apply the DVR in the distribution systems with voltage in range of kilovolts, series converter as one of the important components of DVR should be implemented based on the multilevel converters which have the capability to handle voltage in the range of kilovolts and power of several megawatts. So, in this paper a configuration of DVR based on asymmetrical cascade multicell converter is proposed. The main property of this asymmetrical CM converter is increase in the number of output voltage levels with reduced number of switches. Also, the pre-sag compensation strategy and the proposed voltage sag/swell detection and DVR reference voltages determination methods based on synchronous reference frame (SRF) are adopted as the control system. The proposed DVR is simulated using PSCAD/EMTDC software and simulation results are presented to validate its effectiveness.