Power Electronics for Bulk Power Flows
The future power system will involve connection of a great number of large renewable energy schemes and other new low-carbon generators that will be needed to reduce emissions and maintain the continued security of supply. These new connections and subsequent bulk power flows will require network reinforcement. The traditional methods of increasing bulk power transfer capacity are reconducting existing circuits, upgrading to a higher AC voltage and constructing new lines. However, these options, particularly ones which involve new overhead line routes, are difficult to implement due to planning constraints and environmental concerns. FACTS devices can increase the capacity of AC circuits while HVDC, especially submarine routes, may be used for the addition of new capacity.
Figure 11.1 (also refer to Plate 7)  shows an example of network reinforcement using FACTS and HVDC. This proposed network reinforcement in northern Britain to bring windgenerated electricity to London includes two submarine cable circuits and extensive series capacitor compensation on the terrestrial 400 kV AC overhead lines. The East Coast HVDC link is being constructed as a CSC-HVDC while the West Coast HVDC link may use multi-terminal VSC-HVDC.
More speculatively, an offshore HVDC grid has been proposed that builds on the 11 submarine circuits currently operating and 21 others being considered across the North and Baltic Seas. This will lead to ...