Research On Simulation Of Direct Drive Wave Energy Generation System Based On Fuzzy Controller

Ocean power generation technology is one of the most exciting research areas due to vast but untapped energy potential worldwide.Technologies on ocean wave marine energy have been explored for centuries but there is no mature technology exist and still undergoing with challenges.In the past decades,different types of wave energy conversion(WEC)devices have been developed.Among the WEC devices developed,Archimedes wave swing(AWS)is the first WEC device for direct-drive power take-off technique and the linear permanent magnet generate(LPMG)is coupled directly to the floater,which leads to simple configuration and high efficiency.Nowadays wave energy converters(WECs)installed have complex mechanical interfaces in their power-take off(PTO)system which results in complicated system structure and more maintenance requirements,these problems are solved in directdrive wave energy converters.1.In this thesis direct-drive wave power generation system and the control strategy of directdrive wave generation are introduced.The controllers for linear generator side and grid side is implemented.The control strategy of the LPMG side controller has to objectives extracting maximum power from the wave and minimize the generator losses.The output power of the WEC fluctuates and the frequency and magnitude of the terminal voltage vary.To provides a steady DC-link voltage,which is then used to feed the mains grid or local load via a 3-phase inverter bridge.The dc-link bus provides a suitable location for energy storage necessary as a buffer to smooth the system power flow from a wave energy converter and to achieve the constant power-flow requirement.The grid side converter controller,aims to output constant active power to the power grid and maintain DC voltage.2.The basic principle of fuzzy logic controller is introduced,and the fuzzy logic controller is designed according to the principle.The control strategy for direct-drive wave generation system based on fuzzy logic controller and traditional PI controller simulation models 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 fuzzy logic controller can achieve the maximum wave energy and reduce the wave power fluctuation.3.The model of direct drive wave energy generation system based on fuzzy controller is implemented in Matlab Simulink.The model of linear permanent magnetic generator(LPMG),its converter is implemented through PI controller.After it LPMG side controller is implemented through fuzzy logic membership function for comparison of results.WEC usually interfaces to the power grid via the back-to-back converter,which consist of two IGBT bridges and capacitor between them.One IGBT bridge is connected to the LPMG controller,named generator side converter,which converts the AC power of the WEC into DC power and stores it in the capacitor.The other IGBT bridge,named grid side converter,being connected to the power grid,using PWM control technique,outputs the constant power and voltage with a constant magnitude and frequency of the power grid.4.The simulation is working properly and obtained the desired results.By comparing the simulation results,it is shown that the fuzzy logic controller results are more stable.The DC-link capacitor voltage and grid injected voltage current output wave forms are more accurate and stable.The same system implemented through PI controller results have distortion and unstable.