Operation of Subsea Electrical Power Systems

Reliable, dependable and cost effective subsea electrical power supply systems have been one of the most important factors in the successful development of the subsea boosting and processing applications and technologies over the last 15 years. This paper will provide an overview of how the system and component parameters and ratings have developed over this period. In the early days of subsea hydrocarbon production, there was a lot of skepticism using high voltage equipment under water - today we know that when the design and qualification is done thoroughly, high availability is achieved on subsea electrical power systems. Further, a focus on what have been the decisive factors for system design, correlation to the end-load and consequently component selection will be offered. An overview of key component qualification methodologies and programs will be described, and finally an overview of operational experience of the existing subsea power systems will be given. The end loads have increased in power rating from some hundred kilowatts to multi-megawatts. This have obviously had a significant impact on the design and utilization of the power components, such as subsea wet mateable connectors, subsea transformers, frequency converters, electrical motors, etc. In parallel to the increase in power rating, and consequently voltage and current, the water depths and environments for installation have changed in this time period and have led to increased requirements to pressure withstanding capabilities, cooling and physical robustness.