Wind power with voltage-, and frequency support as well as island mode
The project will develop and study wind turbine’s ability and possibility to be an active participant in producing renewable electric power and ancillary services to the Swedish grid. The goal of the project is that more wind turbines should deliver ancillary services to the grid and that the security of the supply for the Swedish grid increases.
The project has three parts: Evaluation of operation of commercial wind turbines performing ancillary services, Optimal control for ancillary services, New ancillary services and opportunities for wind power.
Evaluation of operation of commercial wind turbines performing ancillary services
This work is a continuation of a previous project within Swedish Wind Power Technology Centre and will study how well different commercial wind turbines will deliver different ancillary services. The evaluation method on the delivery will be tested and validated on Chalmers wind turbine.
Optimal control for ancillary services
This work package will design a control algorithm that seeks to find the right balance between fundamentally contradictory objectives: maximum electricity production, minimal loads and maximum readiness to deliver voltage or frequency support. How this balance looks and should be made depends on which ancillary service has been promised, a number of turbine-specific factors, such as the mass inertia of the rotor, speed in the pitch system, the design of the blades, but also the wind conditions and current prices for produced electricity and ancillary services. Understanding how this balance looks provides qualitative guidance on which turbines are most suitable for each ancillary service, but also how future turbines should be designed when considering the increased demand for voltage and frequency support. Chalmers wind turbine will be used to test the developed algorithms in operation.
The multi-objective optimisation will be used to analyse how new measurement variables can be used effectively. Current methods based on the Cp-lambda curve appear to have a small delay, which gives them slightly worse performance from a control point of view. Initially, new methods are investigated to predict instantaneous possible production based on load sensors in the blades together with predictive control algorithms. Methods to predict production, based on machine learning, could also be used in this context. The potential of using wind measurements from upwind turbines in a farm will also be analysed.
New ancillary services and opportunities for wind power
There is currently a lack of clear structure for how compensation for reactive power should be designed. Therefore, this work package will start by compiling international experiences regarding how compensation is done, as well as compiling existing solutions for compensation of reactive power in Sweden. This work package will also examine the theoretical voltage regulation capability from 2-3 wind farms at their connection point to DSO or TSO. This analysis is conducted given the electricity grid structure, the type of wind turbine and the requirements from electricity grid regulations. The result is a picture of the ability to deliver reactive power at the connection point as a function of active power given an optimization of the available wind turbines.
Island operation is a special operating condition that is rarely used in Sweden. The goal of this study is to investigate island operation of a wind farm in a smaller island network with a certain load as well as some other production. The goal is to study the transition to island operation and frequency regulation in island operation. For the first part, the focus will be on the separated island network's ability to handle the power variations that may arise. For the frequency regulation in island operation, a sensitivity analysis of the share of wind power in a hydropower-dominated island grid and its impact on frequency quality and frequency stability will be studied. The disconnection and reconnection of the island network to the main grid are not studied, as the island network is considerably smaller than the main grid. In addition, Chalmers wind turbine will be run in island mode. The test site will be complemented with a battery for this part.