Direct control of Wind Parks by a Transmission System Operator.

In Germany, the combined installed power of Offshore and Onshore wind energy generation has surpassed 60 GW. More than 50% of this capacity is located in the control area of the German Transmission System Operator (TSO) TenneT TSO GmbH (TenneT). Wind energy plants are usually connected to the high-voltage grid and therefore primarily controlled by Distribution System Operators (DSOs) or direct marketers. As a result contingencies located in the extra-high voltage (EHV) grid or its connection to the lower voltage grid need to be resolved by cooperation between the grid operators involved. Currently, the coordination required for the implemented cascaded process takes several minutes. Especially in an emergency state, such a task could e.g. be accelerated by establishing a direct control mechanism for TSOs in addition to the coordination with the DSO. By that, contingencies can be dealt with on a shorter timescale. As part of the funding program 'Smart Energy Showcases (SINTEG)', TenneT initiated a collaboration in the showcase region of 'NEW4.0' in Northern Germany. Together with direct marketers ANE GmbH & Co. KG, Statkraft Markets GmbH, virtual power plant service providers ARGE Netz GmbH & Co. KG, Energy & Meteo Systems GmbH as well as Fraunhofer Institute for Energy Economics and Energy System Technology (Fraunhofer IEE), several wind parks, were connected to the TenneT control room in different subprojects using different interfaces in order to compare both approaches. As part of different field tests those wind parks were curtailed and the resulting effect on the power flow from high voltage to EHV grid was measured directly at the transformers in the vicinity. This allowed the estimation of the potential influence of a control mechanism. While positive results were achieved and the effect of single wind parks could be measured without further knowledge of the medium voltage grid model, a clear conclusion is yet to be made. A permanent implementation usecase heavily depends on the outcome of the redispatch process being remodeled in the light of new legislation in Germany ('Redispatch 2.0'), as the possible synergies with measures of the alert state using the upcoming interfaces are yet to be determined. [ABSTRACT FROM AUTHOR]