Research On Control Technology Of Direct-drive Wave Power Generation System For Island Microgrid

With the release of ocean development strategy,the development of marine industry and marine economy in coastal areas,direct-drive wave power generation and multi-energy complementary island micro-grid have attracted more and more attention of researchers.In this paper,a DC bus island micro-grid including wave energy,wind energy and solar energy complementary power generation and composite energy storage of super capacitor and battery is studied and designed.By using the control strategy of direct-drive wave generation system based on biological intelligent control algorithm,the fluctuation of the output power of the wave power system is reduced.The stability of multi-energy complementary power generation system is improved by using super capacitor and battery composite energy storage.The specific research contents of this paper are as follows:1.The research background and significance of this dissertation are elaborated.The research status of direct-drive wave power generation,island micro-grid based on direct-drive wave power generation and the control strategy of direct-drive wave generation are introduced.The two problems of direct-drive wave power generation,maximum wave energy tracking control and output power smoothing,are analyzed.Several commonly topological structures of direct-drive wave power generation system are analyzed and compared.This dissertation analyzes and compares the common grid structure of the island micro-grid based on wave power generation and puts forward a scheme to improve the stability of the island micro-grid with the composite energy storage of battery and super capacitor.2.The mathematical models of renewable energy power generation systems and composite energy storage system in island micro-grid are established.The maximum power point tracking control strategies of direct-drive wave power generation system,direct-drive wind power generation system and photovoltaic power generation system are studied.The typical control strategies of inverter in island micro-grid are studied,including voltage oriented vector control and voltage frequency control.3.The basic principle of biological intelligent algorithm is introduced,and the biological intelligent controller is designed according to the principle.The control strategy of direct-drive wave generation system based on biological intelligent algorithm is put forward and the PSCAD simulation models of direct-drive wave generation system based on the traditional PID control algorithm and the biological intelligent control algorithm are built respectively.By comparing the simulation results,it is proved that the control strategy of the direct-drive wave power system based on the biological intelligent algorithm can achieve the maximum wave energy tracking and reduce the wave power fluctuation.4.The PSCAD simulation model of DC bus island micro-grid including wave energy,wind energy and solar energy is built,with the composite energy storage of super capacitor and battery used.The simulation results of island micro-grid are carried out.By comparing the simulation results,it is shown that the output power of the direct-drive wave power system with the biological intelligent control algorithm is more stable than the system wih PID,and the stability of the island microgrid is improved after the direct-drive wave power system is connected to the island microgrid.