Variations of Pricing at energy markets caused by energy feed of Offshore wind farms

摘要

In times of dealing more and more balance energy at the European energy exchange the supply characteristics of offshore wind energy plays an important role for the purchasing strategy of the utilities and the hub schedule management. The intermittent feed-in have a stake in the stock market price. For already smaller installed capacities it is urgently necessary to recognize possible fluctuations in wind energy and the input variability to be able to implement strategies for the trade with balance energy. The German Federal Government plans an installation of about 25 GW offshore wind energy capacity in the German territorial waters. For the integration of offshore wind energy into the conventional grid system a compensation of the wind energy fluctuations is needed. More and more transmission provider are using trading desks to get the needed balancing power. Due to the possibility of intraday trade the spot market is very adaptable and can react quickly to possible energy fluctuations. To review the possibilities of the spot market the offshore wind energy fluctuations are modeled with a realistic offshore wind farm model based on the measurement data of the German offshore wind research platforms. Considering a complete offshore wind farm, the compact placement of the individual wind generator units can lead to their interaction. Usually some of the generator units are operating in a windstream already influenced by the units located upstream. Their momentary power output is reduced depending on the wind direction an -of course- the wind speed. The reciprocal interaction is much more distinct in a large offshore wind farm. Depending on the actual wind direction, the number of shadowed turbines and the degree of shadowing of the downstream turbines is intensified. For example, generating units first impacted by the wind front may still be operating within their nominal power output range, whereas the units located further downstream can no longer reach their nominal power output range. This gives rise to fluctuations which have no effect on the energy conversion in first plant rows, and appear only in the power output behaviour of the downstream plant rows. Therefore in order to describe the behaviour of these clusters realistically, a non-aggregated consideration of the wind farms is necessary. Supported by a Merit-Order-Simulation-tool and based on power station database and empirical trading results of the European Energy Exchange (EEX) the action on the marketplace is modeled considering the energy fluctuations of offshore wind energy. The results are discussed in the paper.