Tag Archives: wind power

25-32 A. Annuk, H. Tammoja, H. Agabus, K. Toom and T. Tamm
Possibilities for Correcting Forecast Errors by Cutting off Production Chart Peaks
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Possibilities for Correcting Forecast Errors by Cutting off Production Chart Peaks

A. Annuk¹, H. Tammoja², H. Agabus³, K. Toom¹ and T. Tamm¹

¹ Department of Energy Application, Institute of Technology,
Estonian University of Life Sciences, 56 Kreutzwaldi Str., EE51014 Tartu, Estonia
e-mail: andres.annuk@emu.ee
² Department of Electrical Power Engineering, Tallinn University of Technology,
Ehitajate Rd. 5, EE19086 Tallinn, Estonia; e-mail: heiki.tammoja@ttu.ee
³ Nelja Energia LLC, 1 Regati pst., EE11911 Tallinn; e-mail: hannes@4energia.ee

Abstract:

In this paper we describe a conception for the mitigation of wind power fluctuations by cutting off production chart peaks.
The rapid growth of wind energetics has been induced by several factors. Although the government support may be the main incentive, other important motives include the increasing network access fees and strict requirements set for ensuring the balancing capacity of production.
However, such capacity has the tendency of being underdeveloped. The possibilities of the operating oil-shale plants for providing the capacity to balance the wind parks are running out. Sudden changes in the oil-shale plant output contribute to additional CO2 emissions, increased fuel consumption and decreased boiler efficiency. Under the circumstances, the transmission system operator (TSO) can face the need to reduce the power output of the wind parks. The operators of the wind parks integrated into the transmission network are responsible for presenting to TSO a 24 h forecast of their output power.
The forecast error is mainly specified in terms of Mean Absolute Percentage Error (MAPE), which for Estonian wind parks is about 20% on average. For forecast error estimation we have also applied the notion of Mean Percentage Error (MPE). Estimation of Pakri wind park data shows divergent actual forecast errors for different values of output power. For the values approximating the rated power of the wind park, the actual output power is larger than predicted. This situation clearly arises when the proportional output power is over 80% and MAPE is quite evenly distributed around 19.2%. In good wind conditions, for the relative output power value of 80%, the share of energy lost by cutting off production chart peaks amounts to 8.6% of the total energy production. The share is rapidly decreasing with declining wind conditions. Nevertheless, the average share of energy lost does not exceed 5%. The cut off energy might be applicable for heat production in boiler houses, although it is cheaper than the energy supplied to the electrical network.

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141-148 J. Lepa, V. Palge, K. Jürjenson, K. Toom, M. Pennar and A. Annuk
Wind Power in Heat Energy Systems
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Wind Power in Heat Energy Systems

J. Lepa, V. Palge, K. Jürjenson, K. Toom, M. Pennar and A. Annuk

Department of Energy Application, Institute of Technology,
Estonian University of Life Sciences, 56 Kreutzwaldi Str., EE51014 Tartu, Estonia
e-mail: jaan.lepa@emu.ee

Abstract:

The article discusses opportunities for the use of wind power plants in order to supply heat to coastal settlements. The possibilities of meeting the needs of heat consumption in the city of Paldiski in Estonia using general data from wind power output serves as an example in the present paper. Monthly electricity and heat consumption graphs and schedules of the Republic of Estonia together with production charts of wind power plants were used as initial data for the research. The investigation of wind energy production charts shows that, due to stochastic peculiarities of the wind, it is especially complicated to match the latter and the electricity consumption charts. There have even been cases, where the dispatcher has been forced to limit wind energy production maxima so that it would not interfere with the work of generators at large power plants. However, satisfactory correlation was revealed between the monthly graphs of both electricity and heat energy overall annual consumption, and wind power production charts. Nevertheless, there are still high deviations, and therefore, in order to use wind energy for heating purposes, powerful storage devices or additional feeding units are necessary to level the fluctuations of electric power produced by wind plants.
The problems related to the production usage of wind power plants in heat and power engineering are to a certain extent less complicated due to the fact that heating systems can be supplemented with additional heat energy storages. Considering the above mentioned issues, the authors suggest a more extensive usage of wind power plants for heating towns and settlements, particularly in cases when production peaks interfere with the work of power systems.
Due to new capacity installations, the overall production of the wind power plants is constantly increasing. Thus, the authors recommend that the maximum power usage coefficient of an operating wind power plant, not their overall production data should be used for analyzing the efficiency of the present power plants and for designing new ones. This will be more correlated with power and heat consumer load curves.

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