JIP Prepares for Final Shallow-Water Test of Subsea Power System
Authors: Feder Judy 
Published: July 2019

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper OTC 29550, “ABB Subsea Power JIP—Going the Distance,” by Stian Ingebrigtsen, Svein Vatland, John Pretlove, and Henning Nesheim, ABB, prepared for the 2019 Offshore Technology Conference, Houston, 6–9 May. The paper has not been peer reviewed. Copyright 2019 Offshore Technology Conference. Reproduced by permission.

A joint industry project (JIP) comprising ABB, Equinor, Total, and Chevron, is developing technologies for subsea power transmission, distribution, and conversion. The output will form a critical part of future advanced subsea-field developments. Begun in 2013, the project reached a major milestone in late 2017 when the first full-scale prototype of the variable-speed drive (VSD) passed a shallow-water test (Fig.•1). Final preparations are now underway for a 3,000-hour test of the complete subsea power system with two VSDs in a parallel configuration combined with subsea switchgears and controls.•The complete paper highlights elements of the technical development and an overview of the primary building blocks of the system, and presents in detail some of the challenges in developing, designing, and testing the•control system.

Introduction

A subsea power transmission and distribution system will enable an entire oil or gas production system to be placed directly on the seabed, allowing expansion of development to deeper and more-remote locations while yielding cost and safety benefits from reducing significantly, or even eliminating, the need for topside installation.

The JIP is developing three products for the system:

Subsea VSD

Subsea medium-voltage (MV) switchgear

Subsea control and low-voltage (LV) distribution

Providing a technical solution that is realistic, possible to engineer, tolerant of extreme environments, and reliable in its performance presents a significant challenge. The equipment—the MV switch-gear, control and LV distribution, and the VSDs—must be able to run without intervention for many years. The equipment is qualified for water depths to 3000 m and will have capacity of up to 100•MW with a transmission distance of up to 600 km.

The primary focus thus far has been to qualify the basic building blocks to serve the typical voltage and power ratings for subsea processing. All project-qualification activities follow the recommendations and technology readiness level (TRL) stages defined in DNV Recommended Practice (RP)-A203, applicable for components, equipment, and assemblies in hydrocarbon exploration and exploitation offshore. This RP provides a systematic approach to ensure that the technology will function reliably within specified limits, and it provides a common understanding and terminology of technology status and risk management. Other important aspects of the RP include the ability to identify required design changes at an early stage and to improve confidence in the new technology by close interactions and traceable•documentation.

To ensure compact and reliable solutions, oil-filled pressure-compensated tanks are used for enclosure of the VSD and switchgear. All components are tested extensively under the full pressure they will experience at the target water depth. A high-level objective of the project is to design the equipment to minimize production downtime and the number of retrievals.