Briefing: Connecting offshore windfarms to the grid by HVDC

Abstract

Several very large offshore windfarms are now planned for construction in hostile, remote locations in waters around the UK, where they present some significant new engineering challenges in bringing large quantities of electrical power back to shore. The design, construction and operation of large-scale power plant 100 km or more out to sea requires considerable design and construction skills. These windfarms require very robust electrical transmission systems with high availability and minimal maintenance requirements that meet strict national grid codes and also relieve stresses from the wind turbines by isolating electrical transients from the mainland grid. The systems must also be suitable to withstand the harsh conditions of the North Sea. This paper highlights how high voltage direct current (HVDC) systems utilising voltage-source converter (VSC) technology are set to play an important role in connecting offshore windfarms to the grid, and outlines the solutions that are now successfully being rolled out.