计及器件不同结温变化因素的风电变流器可靠性评估

发布时间：2018-03-16 16:53

本文选题：风力发电　切入点：变流器　出处：《重庆大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着大规模风电场广泛地投入应用，机组的可靠性问题也越来越受到人们的重视。变流器作为机组的核心部件，其运行功率波动性大，可靠性远远低于一般工业用变流器的可靠性水平。作为电力电子设备，变流器主要功率器件的结温随风速连续波动，是造成变流器故障率高的根本原因。本文以直驱永磁同步风电机组中的全功率变流器为研究对象，重点研究不同风速下功率器件结温波动的特点，不同结温波动的变化时间尺度，以及最大风能跟踪控制方式下，机组暂态过渡时间对风速采样时间间隔的影响。最后，提出计及不同时间尺度的离线风电变流器可靠性评估模型，并分析了运行、设计参数对可靠性的影响。本文的研究内容包括以下几个部分： ①根据结温功率损耗计算公式和热网络模型，基于Matlab/Simulink平台，搭建了风电变流器功率模块的结温仿真模型，并对不同风速下功率模块的结温波动特点进行分析。首先，分析了恒定风速运行下，功率模块结温平均值和结温波动幅度的变化特点；其次，分析了变风速运行下，阵风、渐变风以及噪声风对结温波动的影响，总结出风速变化持续时间与结温波动的关系；最后，分析了随机风速运行下，结温的波动特点，为基于结温变化特性分析，提出变流器可靠性模型奠定基础。 ②针对变风速下长时间尺度的结温平均值波动，通过对机组的暂态变化特性进行分析，提出风速采样时间间隔的选择依据。首先，将结温采样点评估结果和仿真结果进行对比，说明风速采样点时间间隔选择的重要性；其次，通过推导风速突变后，机组最大风能捕获控制方式下的暂态过渡时间，提出对结温平均值波动信息进行采样点评估时，风速采样时间间隔选择的依据。最后，以某厂家实际风电机组为例，计算了风速采样时间间隔与风速的关系。 ③针对不同时间尺度下结温波动的特点，采用不同方法对各结温波动影响下的变流器故障率进行计算，提出计及不同时间尺度的变流器可靠性评估模型。首先，在建立长时间尺度下故障率计算模型时，对变流器运行状态进行二维划分，并采用雨流计数法提取器件的温度循环信息。其次，在建立短时间尺度下故障率计算模型时，根据功率循环寿命曲线，，采用线性疲劳累积计算模型。最后，考虑两种时间尺度下的故障率，提出计及不同时间尺度的风电变流器可靠性评估模型。并采用该离线评估方法分析了风电机组的运行、设计参数对变流器故障率的影响。上述研究中，考虑结温波动不同时间特性，提出计及不同时间尺度的风电变流器可靠性评估模型，为根据实测风速对变流器进行较准确的可靠性评估及设计提供了参考依据。
[Abstract]:With the wide application of large-scale wind farms, more and more attention has been paid to the reliability of the units. As the core components of the units, the operating power of converters fluctuates greatly. The reliability of the converter is much lower than that of the general industrial converter. As a power electronic device, the junction temperature of the main power device of the converter fluctuates continuously with the wind speed. This paper focuses on the characteristics of junction temperature fluctuation of power devices in direct drive permanent magnet synchronous wind turbine. The influence of transient transition time of unit on the sampling interval of wind speed under different time scales of temperature fluctuation and maximum wind energy tracking control. An off-line wind converter reliability evaluation model with different time scales is proposed and the influence of operation and design parameters on reliability is analyzed. The research content of this paper includes the following parts:. 1 according to the calculation formula of junction temperature power loss and thermal network model, based on Matlab/Simulink platform, the simulation model of junction temperature of wind converter power module is built, and the characteristics of junction temperature fluctuation of power module under different wind speed are analyzed. The characteristics of the average value of junction temperature and the fluctuation amplitude of junction temperature under constant wind speed are analyzed. Secondly, the effects of gust, gradual wind and noise wind on junction temperature fluctuation under variable wind speed are analyzed. The relationship between the duration of wind speed change and junction temperature fluctuation is summarized. Finally, the characteristics of junction temperature fluctuation under random wind speed operation are analyzed, which lays a foundation for the reliability model of converter based on the analysis of junction temperature variation characteristics. 2 according to the fluctuation of the average value of junction temperature in a long time scale under variable wind speed, by analyzing the transient variation characteristics of the unit, the selection basis of sampling time interval of wind speed is put forward. Firstly, the evaluation results of the sampling points of junction temperature are compared with the simulation results. Secondly, by deducing the transient transition time of the maximum wind energy capture control mode after the wind speed abrupt change, the paper puts forward the evaluation of sampling point for the fluctuation information of the mean value of the junction temperature. Finally, the relationship between the sampling time interval and the wind speed is calculated by taking the actual wind turbine in a factory as an example. According to the characteristics of junction temperature fluctuation in different time scales, different methods are used to calculate the failure rate of converter under the influence of different junction temperature fluctuations, and a reliability evaluation model of converter considering different time scales is proposed. When the failure rate calculation model is established for a long time scale, the operating state of the converter is divided into two dimensions, and the temperature cycle information of the device is extracted by the rain flow counting method. Secondly, when the failure rate calculation model is established on a short time scale, According to the power cycle life curve, the linear fatigue cumulative calculation model is adopted. Finally, the failure rate under two time scales is considered. The reliability evaluation model of wind power converter considering different time scales is proposed. The off-line evaluation method is used to analyze the operation of wind turbine and the influence of design parameters on the failure rate of converter. In the above research, considering the different time characteristics of junction temperature fluctuation, a reliability evaluation model of wind power converter considering different time scales is proposed, which provides a reference for the reliability evaluation and design of converter according to the measured wind speed.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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