INTEGRATED POWER SYSTEM OF SERIFOS ISLAND WITH HIGH RES PENETRATION USING PUMP-STORAGE
Figure 2 -The lower reservoir in the phase of construction3
Modelisation and simulation The operation of the IPS of Serifos was simulated in order to define the optimal size of each subsystem that comprises the IPS. The simulation code programming was performed under Matlab environment. The code was carefully studied, so that all the important parameters (controlled and non), which influence the operation of IPS, were considered. The non-dynamic type of simulation is using ten-minutes time series. Each unit of the IPS has been modeled in a separate routine so that the main program calls it to run each time: a) Wind turbines (WP=1) The characteristic power curve for the above-specified WTs was taken from the technical manual for the Enercon E40. Attention was paid to the conversion of wind data from the typical height of the 10m mast to the hub height. For simplistic reasons, the simulation takes into consideration that the appropriate calculations for this conversion are based on two phenomena of the airflow that combined together result into the velocity deviation among different heights. First comes the boundary layer that is expressed by the exponential law assuming the suitable roughness length of ground. Afterwards, comes the speed-up effect due to topographic elevation since the WP is not sited on a flat terrain. The Guidelines method of Taylor and Lee (1984) 9 has been found to give reliable estimates of wind speed on tops of certain terrain features like 3D hills, 2D hills (ridges) -this is it in our case-, 2D rolling terrain and others. After evaluating the wind speed at hub height the corresponding output power of each WG is calculated through the power-curve given from manufacturer. The power is supplied to the grid with an electrical efficiency of 0.97. Finally, we assume an availability factor of 0.95. This means that 5% of the days of the year are randomly chosen by the program to give zero power. So we avoid decreasing the nominal output of WTs. b) Variable speed pumps (HS=2). During the simulation the operation point of pumps is calculated in function to current required power P to absorb. The performance curve of the pumps and the characteristic curve of piping are used to define the operation point9. Each operation point (H,Q) refers to a unique combination of valve opening, operation speed and number of operating pumps. 85