Performance of wind-solar integrated grid connected energy system

A. Annuk¹, P. Pikk¹, E. Kokin¹, E. S. Karapidakis² and T. Tamm¹

¹Department of Energy Engineering, Institute of Technology, Estonian University of Life Sciences, 56 Kreutzwaldi Str., EE51014 Tartu, Estonia; e-mail: andres.annuk@emu.ee
²Department of Natural Resources & Environment (Chania), Technological Education Institute of Crete, P.O. Box 1939, GR 71004, Iraklio, Crete, Greece;
e-mail: karapidakis@chania.teicrete.gr

Abstract:

In this work the system of wind generator and PV panel connected to the grid is discussed. The unit wind generator and indicative solar data converted to relative values were used. The ratio between energy amount going to the grid and produced energy was analysed for different energy demands in case of varying wind power levels and solar irradiation intensities. In case of produced and consumed in site yearly energy is equal, the amount of energy supplied to grid and consumed is approximately equal to 50% of energy production. With the increase of wind energy part, this ratio diminishes. Wind – PV panels’ solution is most effective in case of energy selling to the grid at low demand periods. The possibility of Photovoltaic Geographical Information System ;PVGIS) database application for solar data modelling was also analysed. For summer months the differences between the PVGIS database and measured data from Estonian Meteorological and Hydrological Institute (EMHI) do not exceed 5%, though in winter months it reaches 25%. But as on the latitude of Estonia the PV panels’ energy production in winter is marginal compared to summer then its influence on the energy balance is very small.

Key words:

consumption factor, solar database, wind power penetration

The Estimation of Wind Lull and Consumption Factor Influence on Autonomous Wind Energy System

V. Põder, T. Peets, K. Toom and A. Annuk

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

Abstract:

Due to the stochastic output of wind generators, some kind of storage device will be necessary to ensure a constant energy supply by an autonomous energy system. The necessary storage capacity depends on wind data and consumption factor. The latter describes the ratio between average production capacity and average usage capacity. In addition to average wind speed, the frequency and duration of windless periods must be considered as well. The concept of energy lulls has been outlined to describe the influence of duration, frequency and distribution of wind less periods on a wind energy system. Location has strong influence on energy lull length; the difference in average duration between a coastal area and inland is more than two fold. Weibull distribution can be used to describe the probability of energy lulls.

Key words: