Page 54: of Offshore Engineer Magazine (Sep/Oct 2015)

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EPIC

Modeling in the deep

An approach to modeling and simulation combining subsea electrical and fuid systems can facilitate a better understanding of the interaction of long-distance tiebacks supplied by step-outs.

ABS’ Milton Korn explains.

he great distances and diffculties stations are located along the in placing equipment and systems tieback to achieve the desired

T associated with subsea production fow for the piping system.

Voltage variation along the length of an unloaded exert extraordinary pressures on equip- Linear step-outs supplied

Images from ABS.

transmission line at fxed frequency. ment/system installation and commission- from shore are coupled to the

Advanced power systems ing to “get it right” the frst time. tieback at multiple points along

Subsea power system requirements are

The cost of rework and lost production its length to deliver electrical energy at the challenging the functional limits of tradi- can be compounded by environmental required rate and appropriate quality for tional equipment and systems. The velocity and economic extremes, which pose pumping and compression stations. and magnitude of change to equipment and major challenges as evolving subsea Subsea modeling gives engineers a systems have raised concerns about the reli- concepts transition into the feld. Failed way to individually and collectively ability of power systems that incorporate installation can be fxed, but a failed evaluate the operation of the electrical these new technologies and the adequacy design places additional impediments in power systems, tieback and the pump- of the analysis techniques used to predict the way of successful operation. ing/compression stations during normal equipment and system performance.

Several years ago, ABS started devel- operation scenarios such as startup, oping simulation capabilities as part of ABS models are being developed to acceleration, production and shutdown its technology program. The resulting study equipment and system performance as well as during transient events. This modeling and simulation profciencies under a variety of normal and fault operat- approach also allows for examination of provide insight into equipment/system ing conditions. These same models will anticipated system performance during design and operation, including subsea also allow engineers to study the optimal fault events and allows for correction power systems. coupling point of energy storage systems. and optimization prior to deployment.

Applying simulation in the electrical Optimizing the coupling point of energy Correction prior to deployment provides and thermal fuid domain provides a storage systems offers the opportunity to the opportunity to reduce the risk of means of exploring aspects of equipment reduce capex by providing the potential to catastrophic failures such as an environ- and system that were not possible previ- justify reduction in the size and number mental incident, personal injury, damage ously – until a system had been installed of onboard generators. Opex and emis- to equipment or loss of production.

The ABS Modeling and Simulation and commissioned. These simulation sions can be reduced using this approach team explored the transient nature of capabilities can be used for subsea because it provides the opportunity to run energizing subsea transmission systems, operations as well as operations on the minimal set generators at their lowest including capacitive charging current, marine and offshore assets that deploy cost/emissions point.

the Ferranti effect and the dependence of sophisticated and complicated power

Subsea power systems research transmission line voltage on both time and systems that were not imagined a few

Transient response and resonance at the receiving end of transmission line during switching events.

position along the line. Working from the short years ago. Pumping stations and compression

September 2015 | OE oedigital.com 56 056-OE0915_EPIC1_ABS.indd 56 8/19/15 6:39 PM