Dynamic wake analysis of a wind turbine providing frequency support services

Abstract The participation of wind farms in providing ancillary services is an asset for the power system and one way to maintain a strong grid with the increasing penetration of renewable energy sources. Research has shown this to be feasible for wind farms by using efficient prediction and sophisticated control systems. In some parts of the world, strict grid codes are already being implemented that require wind farms to provide ancillary services. Moreover, the primary reserve market in Europe is moving towards shorter procurement periods, providing wind farms an opportunity to more efficiently optimise their resources based on short term forecasts. It can however be challenging for the wind farms to efficiently participate in grid frequency support services, especially for primary reserve services. The reason behind this is the requirement of quick activation and deactivation of power reserve margin for services such as Frequency Containment Reserve (FCR) and Fast Frequency Response (FFR). A full activation of the contracted reserve is required within seconds of a grid frequency dip. A sudden change in wind turbine dynamics is expected to have an impact on the wake behind the wind turbine. The wake effect within a wind farm is taken into thorough consideration in its design process. The effect on the wake due to the wind turbines participating in fast response ancillary services however, remains unexplored. This is a matter of greater concern for wind farms with a high capacity density. To this end, the main contribution of this article is to observe the effect of ancillary service based control system on the wake effect of a wind turbine. Additionally, the capability of developed wind turbines controllers to follow primary reserve services are also tested. FFR and FCR services are tested for a range of frequency designs, these include both synthetic and actual grid frequencies. The synthetic frequency profiles are designed to replicate both fast and slow frequency variations in order to analyse the impact on wake behaviour. The simulations are performed for low and high wind speed including constant as well as turbulent winds.