Voltage Sag Compensation in High-Quality AC/DC Converters Using the Single-Phase DQ Theory

Voltage sags are one of the most important power quality problems, affecting industrial and commercial customers. Industrial processes are particularly sensitive to relatively minor voltage sags. Utilities have been improved their fault-recovery capabilities, however it is still impossible to eliminate faults in the systems. Therefore, customers will have to improve the ride-through capability of the system equipment in their facilities. This paper presents the application of the single-phase DQ theory as a simple method to detect voltage sags in the AC mains obtaining the voltage peak value. This information can be used to achieve, by analytical manipulations, the input current adjusting during the sag, in order to maintain the load power constant. Applying the above considerations to a single-phase five-level PWM rectifier both objectives power factor correction in steady state and voltage sag compensation in transient state are gotten. Simulation and experimental results have been carried out in a 1 kVA, single-phase power converter