Ormen Lange Long Step-Out Power Supply

Abstract

This paper gives an overview of the Ormen Lange LongStep-out Power Supply (LSPS) system which shall provide power and communication over the 120 km step out distance from Nyhamna west coast of Norway to the subsea gas compression station. The document will present status including technical description and qualification programmes. Transmitting 65 MW over a distance of 120 km is challenging not only related to voltage and power loss at full load, but also to the voltage stability at number of different load scenarios, such as reactive power production in the cable which is also present in no load situation. The subsea mounted Variable Speed Drive (VSD) dictates stringent requirements to voltage variation and stability of the power supply system. Limited track record and maturity of components and equipment meant that development and qualification testing would be necessary to ensure sufficient reliability of the subsea power supply system. On this basis StatoilHydro decided to include the LSPS system in the pilot testing of the subsea gas compression at Nyhamna west coast of Norway. The LSPS pilot project was kicked off in July 2006. Since then development and testing of LSPS equipment and components has been ongoing. The status of the Long Step-out Power Supply project is that all the qualification programs have been successfully completed together with most of the manufacturing for the pilot LSPS. System test for the LSPS pilot system is scheduled to take place during October 2009. Hook up and mechanical completion at the Nyhamna test site is scheduled for first quarter of 2010.The purpose of the LSPS pilot system is to test and qualify components and equipment to be used in the LSPS permanent system as far as practical.

Integration of IEC 60287 in Power System Load Flow for Variable Frequency and Long Cable Applications

“…Cables More and more offshore platforms and subsea stations are requiring power (up to 50MW) from land remotely via long submarine power cables (over 100km) for the Oil&Gas industry [4]. Due to tough environment and limited space, reactive compensation is preferred to be done at one end onshore.…”

“…Another emerging demand for long power cables comes from the development of subsea oil pumping and gas compression, which requires MW level of power for each subsea consumer with step-out distance ranging from tens of kilometers to a couple of hundred kilometers. In addition to long submarine cables, the application usually requires variable speed drives (VSDs) located on the offshore production platform which introduces variable frequency operation (up to 200Hz for high power subsea compressor motors) over long cables [4], [5].…”

Electrification of Subsea Systems Requirements and Challenges in Power Distribution and Conversion

“…As the subsea loads such as ESPs and compressors are located very far from the onshore generating stations, it requires a long tieback power transmission system. Subsea industry has already started using high power high voltage AC transmission systems in order to minimize the power losses, and the reactive power due to the large capacitance of the power umbilical [16], [17]. The high voltage direct current (HVDC) transmission system in the subsea industry is being considered as an efficient power transmission solution for the long tieback subsea power systems as the number of power conductors and the reactive power consumption are minimal [18].…”