Research On Maximum Power Capture Technology For Horizontal Axis Tidal Current Turbine

With the development society, energy demanding by industry and civilian use has grown rapidly which leads to a large amount of consuming of traditional energy resources and made these non-renewable resources exhausting. In addition, excessive carbon dioxide emission leads to deterioration of ecological environment. Therefore, development and utilization of clean and renewable energy become imminent, arousing wide attention around the world. As the key equipment of marine energy development, the power coefficient of tidal current turbine is related directly to the success of tidal current generation. Because of tidal current's cyclical fluctuation, the turbine's output power will ripple. Since the domestic tidal resources are low, it makes lower energy range can be used. Therefore, how to achieve stable power output and capture maximum energy from tidal current power generation equipment will be a key technology.This article focused on the research of maximum power capture strategy and the control system of horizontal axis tidal current turbine, comprehensively considering features of both wind power generation technology and the unique characteristics of tidal current energy power generation.Firstly, this article reviewed a large number of scientific literatures both at home and abroad, and discussed the background, prospects and significance of tidal current energy generation. Then the development situation, main power control technology and variable speed constant frequency technology in the world were reviewed. The project significance and main research contents are also presented.The basic theory of tidal current energy generation and its properties were studied. Moreover, the lift coefficient, the drag coefficient, and pitching moment coefficient of the blade were analyzed. The principle of blade pitch adjusting was also addressed as well as analysis of blade stress.The basic compositions of the tidal current turbine power generation and the control system topology, including permanent magnet synchronous generator (PMSG), diode Rectifier Bridge, and Sepic-DC/DC converter were introduced. Then the method of pitch adjusting and driven approach was discussed. The type selection of generator and dc servomotor, as well as the principle of power conversion system and the torque calculation of blade were detailed introduced. By introducing a large number of wind turbine maximum power capture strategies, and based on the characteristic of PMSG AC tidal current turbine generation system, the article proposed a variable-step derivation MPPT algorithm, which can overcome the shortcomings of traditional fixed step HCS and three-point method.Virtual instrument technology and embedded real-time operating system were adopted to complete the experimental model control system of tidal current turbine. Through variable-pitch system, it greatly improved the turbine's self-start performance. By adjusting load, the maximum power point tracking was implemented. It also verified the feasibility of MPPT algorithm, improves tidal current turbine power coefficient effectively.