Mathematical simulation of hybrid systems. The system of Ikaria

A. Rippi, Mathematical simulation of hybrid systems. The system of Ikaria, Diploma thesis, 135 pages, Department of Water Resources and Environmental Engineering – National Technical University of Athens, Athens, June 2013.



The hybrid energy system (HES) of Ikaria is being analyzed, which is under construction and combines two forms of renewable energy source (RES) for electricity generation, the water potential of excess water in the dam Pezi and the wind potential in the area Stravokountoura. The project will consist of: (a) two water tanks in the areas Proespera and Lower Proespera, which will be accompanied by two Small Hydropower Stations (SHPS), (b) a wind farm (W/F) in Stravokountoura with three wind turbines (W/T), (c) a pumping station in Lower Proespera and (d) the Control Center and Dispatching of load in the existing thermal power station in Agios Kirikos. The SHPS in Proespera will receive, through a steel duct, the excess water from the reservoir to the irrigation dam Pezi for energy production. The water, exiting from the Proespera’s station, ends in the adjacent tank. Then the same quantity of water is directed, through a steel duct, to the Lower Proespera’s SHPS where it is used to generate additional energy and then it is concentrated in the second reservoir. The energy produced by the W/F, is fed to the electricity grid but mostly to the pumping station where the water is pumped and transferred, through a steel discharge line from the lower to the upper reservoir and hybrid energy is being re-produced by the Lower Proespera’s SHPS. The objective of this work is to find a representation model of the hybrid system, in accordance with the rules and assumptions of its design, but also to simulate it for 50 years. The representation model has been developed with the Microsoft excel program, while the approach of the simulation was done with the help of two stochastic simulation models in hourly time step. Specifically, the design of the representation of the system was initially attempted for one year according to the meteorological and hydrological data which had been provided by PPC Renewables S.A. and the technical features of the project. However, a simulation of the hydrological budget of the Pezi reservoir had been attempted in order to assess the available volume to be exploited for the hybrid project. Then, synthetic time series of the electricity demand, input-runoff and wind speed had been created in order to simulate the system for 50 years and which were used for the calculation of electricity which is produced by the W/F of HES. We analyze the methodology of modeling and processing the available data from which some meaningful outcomes can be concluded about them. Then, these data are entered into the representation model of the system in order to simulate the energy budget of the hybrid project on an hourly basis for 50 years. In this effort of simulation, some alternative operating scenarios are being considered in order to note the sensitivity of the system by changing the participation of its various components (SHPS, W/F, pumped-storage, etc.). Eventually, these processes lead to conclusions about the efficiency of this project to meet the electricity demand, the degree of its elements’ participation and generally how it works.

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