Challenges in Offshore Power Systems: Pushing HVac Transmission to the Limit

During the early design stage, it was decided to use high-voltage alternating current (HVac) power transmission to provide power to a large offshore field. Ninety-km 230-kV-rated submarine cables were utilized to transfer ac power to wellhead platforms (WHPs) with electrical submersible pumps (ESPs) required for artificial lifting. Shunt reactors were used for voltage control and to maximize power transfer capability through submarine cables. This combination poses various challenges in steady-state operation and switching transients. This article discusses some of the challenging aspects of such applications, including shunt reactor sizing, transient recovery voltage (TRV), and voltage transformer (VT) discharge. In addition, this article presents various simulations performed to select optimal system parameters and configurations for successful system operation. Reactive compensation configuration and control will be discussed along with the potential delayed zero crossing phenomena.