Study Of Health Condition Monitoring And Assessment For Critical Components Of Large Wind Turbine Generator Systems

With the increasing capacity of a high-power wind turbine generator system(WTGS),its flexibility increase rapidly.The present situation of the high failure rate and high operational cost has been attracted by the wind operators,manufacturers,and third-party operation companies.In order to obtain the health status,get the potential fault symptoms of early detection,reduce the failure rate and reduce operational costs,ensure the efficient operation of the WTGS,it is necessary to execute the study on health condition monitoring and assessment of the TWGS.The WTGS with doubly-fed induction generator(DFIG)as the research object is in this thesis.The research documented in the thesis addresses based on the data driven condition monitoring and its residual life prediction of wind power bearing,based on the failure mechanism the condition monitoring of the IGBT module from wind power converter,and the health conditions assessment of a WTGS by using the method of multi-information fusion.The main studies and achievements are as follows.(1)Due to the values of temperature data change within wide ranges in varying operational conditions,a deterioration condition of wind power bearing cannot be detected adequately through deterioration degree function with traditional fixed threshold,and a probability analysis method of progressive changes of wind power bearing based on temperature characteristic parameters is proposed.Firstly,the dynamic threshold method was proposed by using the data fitting and cluster classification method with the information of temperature characteristic parameters and wind turbine rotate speed.Secondly,considering the effects of different operation conditions and lifetime on degradation degrees,the probability analysis of progressive change method for different monitoring cycle was presented.Finally,taken as an example of progressive change of wind turbine generator rear bearing deterioration,based on the history monitoring data of a practical wind farm,both the method of dynamic threshold and probability analysis of progressive change were demonstrated by comprising with fixed threshold method.(2)Since the traditional remaining useful life(RUL)prediction method of bearing based on the on-site experience and national standard RUL formula with compensation factors can only be used to obtain theoretical RUL as they do not consider the degradation speed of wind power bearings over time,the performance degradation model and real-time remaining life prediction method of wind turbine bearings are proposed based on temperature characteristic parameters.Firstly,considering the degradation speed of bearings change with the operational time and external uncertain factors,the performance degradation model is established based on the winner process,and the parameters of performance degradation model are obtained by using the method of maximum likelihood estimation.Secondly,according to the failure principle of the first temperature monitoring value beyond the warning threshold,the remaining life prediction model of wind turbine bearings is established based on the inverse Gaussian distribution.Finally,taken as an example of the remaining life prediction of a practical generator rear bearing,the process of performance degradation and real-time remaining life prediction are demonstrated by comparison with the practical remaining life.(3)Because the existing condition monitoring methods of base-plate solder fatigue of IGBT module by the infrared thermography are difficult for condition monitoring of base-plate solder fatigue,a condition assessment method of base-plate solder fatigue for IGBT module based on the case temperature difference.Firstly,the 3D finite element model of IGBT module is established,and the junction temperature and case temperature in IGBT module in different delamination degrees are investigated.Secondly,according to positioning chip,identifying steady-state process,acquiring the case temperature standard value based on the case temperature difference,degradation degree calculation of base-plate solder,the condition assessment method of base-plate solder fatigue for IGBT module based on the case temperature difference is established.Finally,based on an experiment platform of wind power converter,the effectiveness of proposed assessment method and finite element model of IGBT module is verified by the simulated experiment.(4)On account of chip failure inside IGBT module because the parts of bonding wires have lifted off,an effective chip number assessment method of IGBT module of wind power converter is proposed.Firstly,considering the switching time of IGBT module for a shorter time,it is difficult to acquiring the data of on-state voltage,and the data of on-state voltage in the time of 1/6 period with continuous conduction is used.Secondly,according to the structure and output characteristic of multi-chip IGBT module,the mathematic relation is deduced between on-state voltage and IGBT chip number,and the effective chip number assessment model of IGBT module is established.Finally,based on an experiment platform of wind power converter,the effectiveness of proposed assessment method is verified by the simulated experiment.(5)Because it is difficult to obtain the effective health conditions of a WTGS by using the existing traditional assessment methods with the weights of evaluation indices,the method of health conditions assessment for a WTGS based on the evidence theory is proposed.Firstly,based on the characteristic parameters of vibration,pressure,velocity,displacement,electric,temperature of wind power bearing,winding temperature of generator,on-state voltage drop and case temperature of IGBT module,and so on,the health conditions evaluation indices system of a WTGS is presented.Secondly,in order to solve the high-conflict problem among the evidences,according to the evidence theory and amendment idea of evidence source,the health conditions assessment model for a WTGS is established.Finally,taken as two examples,based on the practical SCADA monitoring data of a 1.5 MW WTGS,the processes of health conditions assessment are demonstrated by comparison with the traditional assessment method.