Автореферат на - Технически Университет - София

Study of different structures of hybrid systems with renewableenergy sourcesThe objective of this work realized in joint supervision between the Technical University ofSofia and the University of Corsica, consists in studying various configurations of hybrid systemsusing renewable energy sources in two cases: slow variation process (energy aspect – energy balance)and rapid variation (electrical aspect).A review based on recent international literature has been performed on hybrid energy systemboth stand alone and grid connected.The particularity of energy systems using renewable sources is the energy source randomcharacter. Thus, it is necessary to know the resource variation before a comprehensive study of thesystem behaviour. A study of the wind energy and solar potential was implemented on the basis ofmeteorological data from Bulgaria and Corsica and the complementarity of these two resources wasstudied at different time scale. The various stations characteristics are very different both in terms ofenergy potential and temporal distribution, making the results obtained in the later work moreuniversal.The various models describing the behaviour of the hybrid system organs are described andvalidated: photovoltaic and wind energy generators. The objective of this work consists in theanalysis of performances of a Wind/PV/storage system and in its optimal sizing. In a first part, theenergy storage is considered as ideal (efficiency equal to 1) and is sized for autonomous or gridconnected operation mode with several optimization criteria: minimal difference between theproduced and consumed energy, minimum number of faults, minimum faults duration and minimumno-satisfied energy. The results show the interest of storage what ever the running mode is. Thechoice of adapted storage mean was realized after a general presentation of existing storage meansand we chose hydro pumping storage. We developed a method for study the PV/Wind/hydropumpingstorage system behaviour into a limited electrical grid in view to estimate the impact of such storageon the renewable energy systems integration limit level. A case study has been applied to an energysituation similar to the existing in Corsica. The results showed that the storage integration allows thenot used renewable energy decrease, the penetration rate increasing and the conventional energy usedecrease.Concerning the rapid variation process, our attention was focused to the hybrid system organsin which an asynchronous machine take part. Models of induction machines, voltage sourceconverters and control systems were developed. Simulations were performed for three configurations:an asynchronous generator with squirrel cage rotor, an asynchronous machine with wound rotor withsupplementary resistances and a doubly fed induction machine. The simulation model givessatisfying results during the quantitative and qualitative evaluation. We developed an experimentalmodel of the doubly fed induction generator. The simulation model has been adapted andimplemented in a microprocessor system dSPACE allowing the control in real time of the rotorpower converters. The experimental results show a good control operation and will allow wide futurestudies.- 34 -