Fast Dynamic Control Scheme for Capacitor-Supported Dynamic Voltage Restorers: Design Issues, Implementation and Analysis

The design issues, implementation procedures and system analysis for a fast transient control scheme for single-phase capacitor-supported dynamic voltage restorers (DVR) are presented in this paper. The proposed control scheme includes two control loops as inner and outer loops. The inner control loop is used to dictate the gate signals for the switches in the DVR by using the boundary control with a second-order switching surface to achieve fast dynamic response. The outer loop is used to maximize the restoration duration by three operating modes, reactive power control, minimum energy injection, and maximum voltage injection. The mode boundaries will be derived in this paper. By studying the small-signal characteristics of the control loops, a set of design procedures will be derived. A 500 VA, 110 V prototype has been built and tested with nonlinear inductive loads.