10MW Offshore Wind Power Converter System Design

As the core component of wind turbine,converter plays the role of variable speed and constant frequency.The internal structure of the converter is complex,and there are many high-power devices.These devices will produce a lot of heat during the working period.If the heat is not transferred and released in time,the converter will easily fail due to high temperature.Due to the particularity of wind power environment and power generation equipment,maintenance after converter failure is very difficult and expensive.If the stability of converter is poor,frequent maintenance will directly affect the efficiency of wind power generation.The10 MW offshore wind turbine involved in this paper is the largest wind turbine with single unit capacity in China.The heat output of its converter will be much higher than that of other conventional wind power converters in China.Therefore,it is of great significance to improve the heat dissipation capacity of the converter in the limited equipment space.The cooling system which can meet the cooling requirements of 10 MW converter can avoid the converter choke coil temperature exceeding the high limit when the unit is running at full load in strong wind,which will trigger the fan to stop due to fault,thus increasing the power loss caused by the fault,reducing the total power generation of the fan and reducing the economic efficiency of the wind farm.This paper takes the cooling system design of 10 MW offshore wind power converter as the research object.Through the analysis of converter heat source and conventional wind power cooling system,a set of internal and external dual cycle cooling system is adopted to cool the converter.Compared with the conventional water cooling system of wind power converter,the external circulation cooling system adopts a new structure of double cooling fans and plate heat exchanger.After the establishment of the system scheme,the paper studies the selection and calculation process of the core components of the external circulation cooling system,and puts forward the calculation and selection method.In the part of cooling control system design and research,aiming at the requirements of wind power fault voltage ride through and common faults of wind power converter cooling system,a set of solutions is proposed,that is,optimization scheme of control distribution circuit and control logic of cooling fan and circulating pump.Finally,the rationality of the whole cooling system design is verified through the cooling system test and application.On July 12,2020,China’s first 10 MW offshore wind turbine was successfully connected to the grid in Xinghua Bay,Fujian Province.The cooling system of converter studied in this paper is proved to be reasonable in hardware configuration and stable and reliable in control program after several months of commissioning and operation.The cooling problem of converter for10 MW offshore wind power is successfully solved and the expected cooling parameters are achieved.