A Modular Stacked DC Transmission and Distribution System for Long Distance Subsea Applications

A new power transmission and distribution concept—modular stacked direct current (dc) (MSDC)—architecture is described. Its main application is subsea oil and gas (O&G) processing, where the marinization of system components, their reliability and retrieval are the most critical requirements. In contrast to conventional HVDC systems, the proposed MSDC technology achieves the required dc transmission voltage by stacking a number of power converter building blocks in series that are easy to marinize. Since each building block is similar to a standard variable frequency drive, the MSDC technology has potentially much lower cost and higher reliability. Moreover, the modular architecture renders the system fault tolerant and capable of operating in a degraded mode. The architecture is also highly reconfigurable as the field matures and the loads evolve over time. A generic subsea field scenario for O&G has been designed and analyzed. The MSDC architecture and associated system control strategy are developed and tested using a real-time simulation platform together with an experimental scaled-down prototype of 160 kVA.