Research On Operational Reliability Modeling Of Doubly-fed Wind Turbine And Several Related Issues

As the fossil energy is non-renewable and it can cause the problem of environmental pollution and atmospheric warming,clean renewable energy(including water,nuclear energy,wind energy,solar energy,etc.)has been widely developed in the world.In our country,compared to other renewable energy sources,wind energy has the most commercial development conditions and comparative advantages,and has been rapidly developed recently.According to the China Wind Energy Association,till the end of 2015 China's total installed capacity of wind power reached 145 million 360 thousand kilowatts with an annual increase of 16.8%,which accounts for 33.6% of the global market share.The new installed capacity in 2015 was 30 million 750 thousand kilowatts with an annual increase of 32.6%,which accounts for 48.4% of the global market share.At present,the quantity of China's MW wind turbines has reached more than 80 thousands.However,as China's wind power equipment industry development time is short,the core technology and the wind farm operation experience are lacked in the process of China's wind power equipment industry development,In addition,the natural environment of the wind farm in our country is poor,the operation reliability of the wind turbine is not optimistic.Problems include frequent electrical control system failure,the early damage of gear box,generator and other large parts,bladecracks,and even the collapse and burn of the turbines.The operational reliability of the wind turbine has become one of the most important problems that affect the further development of the industry,and it is the outstanding problem that the industry needs to solve urgently.This thesis firstly expounds the rapid development of China's wind power industry and its problems,and points out the urgency of the research of the reliability of wind turbine.Then,this theis introduces concepts of reliability and then summarizes the research of wind turbine reliability over the world.In order to further quantitative expression of the operation reliability,the inherent reliability model of wind turbine is constructed via least squares estimation based on the real-time data of wind turbine.Then,an allocation model is constructed using AGREE method,and the inherent reliability of eight key components is studied.As the reliability of wind turbine is affected by the extreme weather and the maintenance strategies.This thesis uses the environmental hazard analysis matrix and maintenance reliability model to study the actual reliability model of wind turbine.The further reliability of eight key components are studied under this situation.Combined with the fault tree analysis theory,the structure of the wind turbine is analyzed,and the fault tree of each component is obtained via logic structure analyzing of bottom events.According to the reliability evoluation and operational status of wind turbines,the corresponding protection strategies are proposed.Finally,an empirical analysis of the operating reliability model of wind turbine is carried out.First,the actual operating data of the turbines from Hebeibashang A wind field are used to fit the actual operation reliability distribution function.In addition,the proposed operational reliability model of wind turbine was used to predict the operation reliability prediction of wind field for Hebeibashang A wind field.The proposed operational reliability model of wind turbine has been validated by comparing the actual and predicted operation reliability of wind turbines from Hebeibashang A wind field.Reliability maintenance strategies and improvement measures of wind turbine structure are proposed based on the reliability level of wind turbine in Wind A and Wind B.These strategies can help to improve the management level,increase the availability of wind turbines,reduce the probability of downtime,and finally reduce the loss caused by downtime.