Wind farms: certified grid compatibility
The number of wind farms connected to the electricity grid is steadily rising, and proof of grid compatibility is mandatory for grid connection. But what criteria do wind turbines and wind farms have to meet for certification in Germany, for example? PES investigates...
Before wind farms can be connected to the German electricity grid, they need plant- and type-specific certificates which identify the electrical characteristics of the generating unit (wind turbine) and the generating plant (wind farm). Within the scope of certification, experts check basic requirements including short-circuit rating, continuous current-carrying capacity, active and reactive power supply and their control. Furthermore, the power generating unit must also satisfy fault ride-through requirements, for instance in cases of a sudden drop in voltage.
New systems must actively contribute to maintaining the stability of the grid voltage and frequency. This applies both to the medium-voltage distribution grid and to high and extra-high voltage grids. Certification is based on the German Ordinance on System Services by Wind Energy Plants (System Services Ordinance, SDLWindV). Units and systems connected to the medium-voltage distribution network additionally need to comply with the Medium Voltage Directive of the German Association of Energy and Water Industries (Bundesverband der Energie- und Wasserwirtschaft e.V., BDEW) while TransmissionCode 2007 (Network and system rules of the German transmission system operators) is relevant for units and systems connected to the high- and extra-high-voltage grids.
The critical documents of grid integration are the 'Unit Certificate' (for wind turbines) and the 'Plant Certificate' or 'Plant Expert Report' (for wind farms), which wind farm owners must also submit if they want to apply for feed-in tariffs under Germany's Renewable Energy Act (Erneuerbare Energien Gesetz, EEG).
This also applies to the 'green bonus' under the SDLWindV, an ordinance that governs a host of aspects including special requirements for power generating management and fault ride-through. If the unit or system satisfies all requirements, it is eligible for a bonus of electricity fed into the grid.