Research On Key Technologies Of 5MW Three-Level Medium Voltage Wind Power Converter

With the construction of smart grid and the global energy Internet, the permeability of clean energy power generation in the power system is becoming more and more high, and the wind energy as a representative of the clean energy is also getting more and more attention. In recent years, the development of China's wind power has made great progress, and China has the largestwind power installed capacity inthe world. In 2015, China's new installed capacity of wind power was 32 million 970 thousand kilowatts.The cumulative installed capacity of wind power has reached 129 million kilowatts, accounting for 8.6% of the total installed capacity of power generation.With the continuous progress of wind power generation technology,5MW or above 5MW offshore wind turbine with larger capacity and higher efficiency has become the new market demand. As there arelimitations on the current level of power devices, if the existing low voltage converter technology scheme is adopted and more devices or circuits are need to be connected in parallel, resulting in a series of problems, such as circulation, low efficiency and low reliability. In order to break through the technical bottleneck, the medium voltage system of the higher voltage level becomes the best choice. The medium voltage wind power converter can effectively reduce the system current, improve the system efficiency, and the reliability is higher due to the less high voltage power device.On the basis of analysis and comparison of all kinds of medium voltage converter topology,medium voltage wind power converterbased on the diode clamped three level topology is selected as the research object. Firstly, the design method of the main circuit of the 5MW medium voltage wind power converter is deeply studied; secondly, the control strategy of the medium voltage wind power converter is studied,in order to ensure the maximum efficiency of generator power generation and the friendliness of power network access;thirdly, the power unit based on IEGTand converter test system of 5MW medium voltage wind power converter are designed in detail; based on the research of relevant key technologies, a prototype of 3.3KV/5MW medium voltage wind power converter based on IEGT is developed, and a variety of experiments are conducted to ensure the rationality and reliability of the system design; finally, the key technology of marine climate and environment adaptability is studied and the protection method for the converter of wind turbine is proposed, which lays a foundation for further engineering application.