CSI-fed subsea cable transmission for motor drive applications

To supply speed-variable motor drives in subsea stations, a cable transmission system fed by a standard type of current source inverter (CSI) is proposed. Detailed theoretical investigations concentrated on the effects of current resonance phenomena show that an advantageous characteristic of the CSI is to reduce significantly the emitted current harmonics close to the resonance frequency. This 'self-regulating' effect of a CSI-fed cable transmission results in sufficient operating performance, even in the case that power converter current harmonics are exiting the resonance frequency. Comparing theoretical results with field test measurements confirm the validity of the investigations as well as the practical feasibility of the proposed application of a six-pulse CSI up to a cable length of about 20 km.