Dynamic Voltage Restorer with DQ0 Control System

This article introduces the dq0 control system technology applied in dynamic voltage restorers (DVRs). A dynamic voltage restorer is a power electronic device designed to protect electrical systems from voltage sags, swells, and fluctuations. The dq0 control system implements DVR control by transforming three-phase voltage and current signals into direct-quadrature-zero (dq0) reference frames using Park's transformation algorithm. This transformation enables independent control of active and reactive power components through proportional-integral (PI) controllers. Key implementation aspects include: dq0 transformation matrices for converting abc to dq0 coordinates, phase-locked loop (PLL) synchronization for grid frequency tracking, and voltage compensation algorithms that generate switching signals for power converters. The system maintains stable voltage output while controlling current dynamics, featuring advantages such as rapid response to disturbances (typically within 2-4 milliseconds), harmonic reduction through selective harmonic compensation, and improved system efficiency via optimized switching patterns. The control logic typically involves: 1) Measuring three-phase voltages 2) Applying dq0 transformation 3) Comparing with reference values 4) Generating compensation signals through PI controllers 5) Inverse transforming to abc coordinates for PWM generation. Overall, the dq0 control system represents a robust solution for enhancing power quality in electrical networks through advanced signal processing and control algorithms.