SUBSEA DIRECT ELECTRICAL HEATING POWER SUPPLY SYSTEM, DIRECT ELECTRICAL HEATING SYSTEM AND METHOD OF OPERATING A SUBSEA DIRECT ELECTRICAL HEATING POWER SUPPLY SYSTEM

摘要

The present invention relates to a subsea direct electrical heating power supply system (100) for providing electrical power for heating a subsea pipeline section (30), the system comprising input means (110A, 110B, 110C) adapted to couple the direct electrical heating power supply system to a power supply and a subsea variable speed drive (120) for receiving electrical power from the input means and for providing an AC output. The subsea variable speed drive comprises a plurality of series-connected power cells (A1..A6), each power cell comprising an inverter and a bypass device to selectively bypass the power cell. The system further comprises an adjustable subsea capacitor (130) connected to the AC output (121) of the subsea variable speed drive and output means (140) adapted to couple the direct electrical heating power supply system to a subsea pipeline section (30). The system further comprises a controller (150) adapted to adjust the capacitance of the adjustable subsea capacitor (130) such that if the system output voltage is reduced as a result of bypassing one or more power cells (A1..A6) the current output by the direct electrical heating power supply (100) system is increased.