Step change in cost and size for powerful HVDC offshore wind connections

Introduction

ABB has a lot of experience in connecting offshore wind farms with the grid. ABB is a supplier for high voltage cables, has built AC platforms and also realized three connections with VSC (voltage source converter) HVDC technology. With the experiences ABB has made in different projects the experts have now developed a new platform concept which will be presented during the conference.

Approach

The message from the offshore wind market was clear: Today’s offshore HVDC platforms are too big, too heavy and too complex. Long term sustainable solutions must include significant weight and size reduction of the platforms while still maintaining full controllability offshore.

Main body of abstract

ABB has realized the offshore wind connection projects BorWin1, DolWin1 and DolWin2 using the voltage sourced converter HVDC technology, called HVDC Light. The 400 MW BorWin1 HVDC Light offshore wind connection was the first to be installed. The DolWin1 offshore wind connection is able to transmit 800 MW and was handed over to the customer TenneT in 2015. Both offshore converter platforms were designed and built as jacket/topside solutions. The offshore converter platform of the DolWin2 project uses the so-called gravity based structure concept. The floatable platform was installed at its final site in the German Bight in 2015. Once finalized, DolWin2 will transmit 916 MW of power to the German mainland grid making it the most powerful installation of its kind.

The message from the offshore wind market indicates that today’s offshore HVDC platforms are too big, too heavy and too complex with the consequence of long delivery times, high costs and unacceptable risk profiles. Long term sustainable solutions must include significant weight and size reduction of the platforms while still maintaining full controllability offshore. Based on the lessons learned ABB experts have now developed a significantly more compact concept with a reduction by almost 60% and a design which allows business models with clear and simplified interfaces.

Some of the equipment which is used in the existing projects have been removed whereas other parts of the equipment have been built in a more compact way. The design enables 66 kV incoming feeders in the converter platforms meaning that AC substation platforms would no longer be needed. The next generation HVDC platform has a modular base design with clear interfaces and with options to meet client specific requirements at various site conditions. This makes it possible to build different modules in parallel and therefore save manufacturing time. The reduced weight of the platform modules makes it easier to install the platform.


Conclusion

A significantly more compact platform concept was developed by ABB experts. The concept which is presented at the conference allows business models with clear and simplified interfaces.


Learning objectives
Using experiences from realized projects and combining the lessons learned with market needs and develop new concepts is something that could be adapted by the delegates for their own business.