A Hybrid Voltage Regulation Transformer Based on Interline Power Converters

The hybrid transformer is mostly used for voltage regulation and var control with a fractionally rated power converter, which reduces the device cost and increases the overall efficiency compared with the Solid-State Transformer (SST). Conventionally, the voltage is compensated by injecting voltage in series with the load. This paper proposed a hybrid transformer based on interline power converters for voltage regulation. The maximum power delivered by converters is reduced by half compared with the conventional series compensation configuration for the same voltage regulation range. Therefore, the proposed hybrid transformer exhibits a higher overall efficiency covering a wide range of voltage regulation. Comparison between the conventional series voltage compensation method and the proposed interline power converter-based method is presented based on the operation principle, the converter power, and the overall system efficiency. Hardware test results are presented for further validation of the proposed hybrid transformer.