| With the sustainable development of ocean resources and the increasing awareness of ocean environmental protection,people’s demand for the performance of ocean observation instruments has continued to grow.However,traditional methods of power supply are difficult to ensure the long-term continuous operation of unattended ocean instruments and equipment,and it is urgent to seek new forms of electrical energy supply.As a typical ocean renewable energy source,tidal stream energy can provide continuous power supply for ocean instruments and equipment,but the remarkable fluctuation of tidal stream makes output voltage vary in a wide range,which affects the reliability and stability of the power supply system.In this paper,a power converter with boost and full-bridge LLC cascade circuit and a MPPT algorithm with PSO-GWO are presented to achieve the output voltage regulation and power tracking of the tidal stream energy through circuit design,control algorithm,system simulation and experimental verification The main works of this paper are as follows:(1)The power conversion and control circuit for tidal power generation based on Boost+Full Bridge LLC.Combining the characteristics of tidal energy power generation system,a Boost+Full-bridge LLC circuit is designed for the post-processing of electrical energy of tidal energy power supply system of ocean instruments.In this paper,the structure and operation of the boost converter and full-bridge LLC resonant converter are analyzed,and the mixed control modes of frequency modulation and phase shifting expand the gain characteristics.The simulation in Saber and Matlab/Simulink shows that the system achieves a wide input range of 12 V and stable voltage output in the range of 20 V-120 V.(2)The MPPT control method of the tidal stream power conversion based on PSO-GWO.The PSO-GWO algorithm was developed for the MPPT control of the tidal stream power generation system.The model of the tidal stream power generation system was built in Matlab/Simulink,and the power control effects of multiple algorithms under different operating conditions were compared.The simulation experiments show that the PSO-GWO algorithm converges faster with the power increase of 4%-14%,which improves the output power more effectively than other control methods.(3)Development and testing of the power converter for the tidal stream power generation.The power converter was designed and fabricated based on STM32 and power semiconductor devices for the tidal stream power generator already developed in this project and the test platform of the tidal stream power generation system was built.The test results show that the output voltage is stabilized at 12 V for the input voltage range of 20 V-120 V,and the output power is increased by about 4.6%-16%,which verifies the regulated output and power regulation performance of the control system under wide voltage input conditions.The above research shows that the tidal stream turbine power post-processing system constructed based on the Boost and Full-bridge LLC topology and the MPPT control method with PSO-GWO proposed in this paper adapt well to the operating environment in a wide flow velocity range to achieve both more stable output voltage and more power,which improves the stability and service life of the offshore buoy system under the same operating conditions.This research provides design ideas and analysis methods for optimising the performance and lifetime of the offshore buoy power supply system. |
