Voltage sag mitigation using a high-frequency-link cycloconverter-based DVR

Voltage sags, primarily caused by frequent transmission and distribution-level power system faults, have been known to affect many industrial and, commercial customers resulting in yearly losses amounting to millions of dollars. In order to mitigate voltage sags, many solutions at the load-end have been proposed which include constant voltage transformers (CVTs), uninterruptible power supplies (UPSs) and line-frequency-transformer-based series voltage injection devices. These approaches have their respective limitations with regard to capabilities, size and cost. This paper investigates a new approach to mitigating voltage sags using a high-frequency-transformer-link in the series voltage injection approach, to result in savings in size and weight. The paper discusses 3-phase implementation of this approach. It presents simulation results for linear and nonlinear loads and experimental results from a single-phase proof-of-concept prototype.