Research On Storage Technologies Of Ocean Energy Integrated Power Supply System

The power output from ocean energy supply system relies on the environment and climate conditions, which is intermittent and unstable. Installing storage devices in the system to provide energy buffer is an effective method, which can made system run at a stable power output level,even if the loads fluctuate fast or reach the peak.This paper based on the two projects "Research of Offshore Wave Energy and Wind Energy Complementary Power Platform" and "Research and Demonstration of300kW Marine Energy Integrated Power System".After studying charcateristics of every storage devices, I decided to use lead-acid batteries and super capacitors as storages devices in projects.Firstly, making a study on the battery charge and discharge controlling method, this paper put forward a three-phase changing current charging strategy as well as a depth of discharge controlling strategy based on the ampere-hour theory, and designed the algorithm.Then I established the power generation simulation model, including energy storage system, and made a research on the model.The simulation result proved the correct and effectiveness of the designed controlling algorithm.This method could make battery avoid over-charging and over-discharging, thus increase its life and save the project funds.Secondly, This paper designed the structure of wind-wave energy hybrid power supply system based on batteries storage. It consists of a three-phase pemanent magnet generator, non-controlled rectifiers, Boost chopper, bi-directional DC/DC converter, batteries storage system and inverter. Then this paper designed control strategy and established simulation models of the power system without storage and power system based on batteries storage by MATLAB/Simulink software. The comparison and analysis for simulation results showed that the voltage and frequency of the latter system are more stable and it can meet the requirements of the power quality in power supply system when loads fluctuate.Finally, this paper designed the structure of power supply system based on the dual storage system consists of batteries and super capacitors, using AC/DC/AC structure. The dual storage system connects AC bus through bi-directional energy storage converter. We could find from the simulation result that this structure and the strategy can achieve storage by batteries and support the instantaneous voltage by super capacitors.