Wind turbine response for grid stability

Abstract

Electricity grids are evolving to integrate increasing amounts of renewable generating sources. Wind and solar generation, while benefiting the system with a smaller footprint and starting to outperform other sources economically, also introduce challenges to grid stability and frequency control, as they are not directly connected to the grid, thus not providing inertia against frequency deviations from disturbances. This work focused on investigating the potential of utilizing synthetic inertia from wind turbines in order to address this reduced intrinsic inertia of future electrical systems. The amount of available mechanical energy stored on typical wind turbines was evaluated, and a control scheme to release this energy during grid faults was proposed. A model to validate this approach was developed and simulated in Matlab with the power systems package. The simulations showed that grid frequency response after a disturbance deteriorates significantly in high wind penetration scenarios while not using synthetic inertia from wind turbines, and frequency deviation was three times as severe as in a traditional system, for a scenario with 50% wind penetration. Nonetheless, with employment of synthetic inertia and a suitable control strategy, the maximum grid frequency deviation was restrained to the same level as conventional electricity systems, for wind penetration up to 50%. These results demonstrate that synthetic inertia is an effective solution to improve grid frequency control in future grids with high share of wind turbine generation.