Prototyping of 500 kVA Medium Frequency Transformer for Offshore Direct-Current Collection Grid

Offshore wind farms are integrated to a power system via a long distance transmission system and an offshore platform which collects power from wind turbines. To reduce the size of the offshore platform, a medium voltage direct current (MVDC) collection grid based on modular DC-DC converters is a feasible solution. This paper deals with a medium frequency transformer (MFT), one of the most important components to realize compact and efficient modular DC-DC converters. To reduce large winding loss due to proximity effect, an interleaved winding arrangement is applied to the MFT with an amorphous core. MFTs with a rated power of 500 kVA with interleaved and non-interleaved winding arrangements are prototyped and experimentally evaluated. This study demonstrates that the interleaved winding arrangement provides higher efficiency because of the depressed proximity effect, at a capacity of 500 kVA. Our work indicates that the MFT with interleaved winding arrangement contributes to the reliability and miniaturization of the offshore platform.