An Integrated Power Solution for Enabling Large-Scale Subsea Processing: A Base Case for Subsea Standalone Variable Speed Drive in Brazil

Abstract

There is a growing demand within the oil and gas industry for an integrated subsea power system in order to achieve the highest availability of power supply and power distribution subsea. For that reason, since 2010, a subsea power grid system has been under development by Siemens. The purpose of this system is to provide power to subsea consumers like pumps and compressors in deep and ultra-deep waters for long step-outs. The subsea power supply and distribution system, including all its components, is designed and qualified to work at a water depth of 3000 meters, and up to more than 200 kilometres step-out distance. It will offer an integrated, reliable and cost-efficient subsea power solution for multiple consumers at seabed. The development and qualification program is currently in its last stages. Testing of the individual components (subsea transformer, switchgear, variable-speed drive and communication/control system) will be followed by a complete system test. Overall, development and qualification program is expected to be completed in 2016, at which time the system will be ready for a full-scale subsea pilot project. The power system must have standardized, flexible and configurable interfaces to have an optimal fit with the processing system. The integrity of the power system is governed by a dedicated power control and monitoring system which enables transparent and standardized communication with all the power modules. The Subsea Power Grid solution offers an infrastructure with standardized interfaces both on the topside / onshore power generation and to the subsea consumers – both for the power line and for the power control and communication line. This ensures flexible arrangements with the subsea field’s overall processing system without challenging the integrity of the power distribution. One typical application for Subsea Power Grid solution would be a subsea standalone variable speed drive. The aim of this paper is to perform an overall analysis on how a subsea standalone variable speed drive can be integrated in a typical subsea pumping system without sacrificing the integrity of subsea variable speed drive sub-assemblies designed as part of subsea power grid solution.