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Distribution level

Until now, the connection of wind power to the grid has usually been at distribution level. A particular feature of distribution grids is that there is no active management, for example, on transmission level. The distribution grids have to cope with greater distributed generation levels, without reducing the quality of supply to other customers.

The ‘embedded generation’ of wind power benefits the grid: weak grids may be supported by wind power, and users on the line may be better served, as wind power can help to control grid voltage. Power electronics of wind farms can also improve power quality characteristics in the grid. The power, if consumed within the distribution network, goes directly to the user and transmission costs can be reduced. Finally, and depending on the grid code requirements of the relevant control area, wind power may maintain operations in parts of the system, in the event of transmission failures, which would otherwise cause blackouts.

Adding wind power to distribution grids results in similar effects as in the transmission grid: a change in the direction and quantity of real (active) and reactive power flows, which may interact with the operation of grid control and protection equipment. The design and operation practices at the distribution level may need to be modified as additional distributed generation, such as wind power, is added. Distribution grids may have to become more “actively managed,” which would require the development of suitable equipment and design principles. However, the improved grid brings collateral benefits to the distribution grid operator.