A Modular Subsea Direct-Current Electrical-Power System

Summary Subsea processing has been increasingly accepted by the offshore oil and gas industry as a solution to boost production and reduce cost. Accordingly, the subsea power demand is growing to support various processing loads, including pumps and compressors. Depending on the application, the power rating of a field ranges from tens of kilowatts to tens of megawatts, and the step-out distance ranges from a few kilometers to hundreds of kilometers. Considering the hostile and remote environment, a reliable subsea electrical-power system that is suitable for subsea deployment is clearly desired. This paper presents a modular direct-current electrical-power system that is designed for use in a subsea field with medium or long step-out distance. The proposed system consists of multiple modular converters in the subsea station to achieve the required power-conversion functions. It features high reliability, high flexibility, and reduced installation weight. The system operation and protection are presented, and the performance is verified by a laboratory-scale demonstration.