Voltage Support Provided by Three-Phase Three-Wire Inverters With Independent Reactive Phase-Current Injection
J. Íñiguez, Josué Duarte, Antonio Camacho, Jaume Miret, Miguel Castilla
Abstract
During voltage sags, three-phase three-wire power inverters can provide voltage support with several current injection strategies. In general, good results are obtained, except in overvoltage situations when one or more phase voltages exceed the allowed limit in grid codes. In three-wire inverters, this is a challenging problem because phase voltages are coupled. In this article, we present a strategy that performs independent reactive current injection for each phase, which solves the overvoltage problem. This approach also includes a current-limiting technique that guarantees the injection of the maximum active power under safe current conditions. A stability analysis is carried out based on the small-gain theorem. The properties of the proposed control are experimentally validated with selected tests in a laboratory setup. A performance comparison with state-of-the-art control strategies is also included in the experimental validation.