光伏并网逆变器可靠性研究

发布时间：2018-03-11 05:03

本文选题：光伏并网逆变器　切入点：可靠性　出处：《北京交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着传统石化能源储量的日趋枯竭,与大气污染、温室效应等环境问题的日益显著,开发利用高效、清洁和经济的能源成为人们的首选,然而工业调查表明,新能源发电系统故障的很大一部分原因可以归结于并网逆变器的故障,逆变器的可靠性问题已成为较为普遍且亟待解决的现实问题。为了准确评估并网逆变器的可靠性,本文以光伏发电并网系统为例,首先在Matlab/simulink软件中建立了光伏电池以及并网逆变器的仿真模型,通过实测太阳辐照度与环境温度数据,仿真获得逆变器直流电压与交流电流数据,为器件的可靠性建模与计算提供数据支撑。然后搭建了功率器件的损耗与热网络仿真模型,采用基于失效物理的LESIT寿命预测模型,结合雨流计数法与疲劳累积损伤理论,建立了 IGBT模块损伤计算模型。之后分析了功率波动、开关频率等因素对器件可靠性的影响,结果表明:①各种因素对器件的影响首先反映在器件的结温变化上,满足温度越高,可靠性越低的规律;②功率波动所造成的低频结温波动是影响器件可靠性的主要因素;③改变开关频率可以作为提高器件可靠性的一种手段,采用逆变器在全额运行阶段通过适当降低开关频率以改善功率器件可靠性的策略,该策略简单易行,且能极大的提高功率器件的可靠性水平。采用应力分析法计算了除了功率器件的其余器件的失效率,在获得各元件可靠性数据的基础上,分别采用可靠性框图法与蒙特卡洛法计算了并网逆变器平均故障时间(MTTF),两种方法所得结果互相印证。传统配电网可靠性分析时各设备的失效率都采用常数值,然而逆变器作为多元件组成的可修复系统,随着内部元件的维修与更新其失效率也应发生相应改变。针对这一问题本文分别研究了季节、设备老化以及器件维修的设备可靠性的计算方法,给出了相应的结论以及并网逆变器失效率数据。该方法无论是对主动配电网的可靠性研究还是对于并网逆变器自身检修周期的确定都具有一定工程价值。
[Abstract]:With the depletion of traditional fossil energy reserves and air pollution, Greenhouse Effect and other environmental problems, the development and utilization of efficient, clean and economic energy has become the first choice. However, industrial surveys show that, A large part of the fault of new energy generation system can be attributed to the fault of grid-connected inverter. The reliability of inverter has become a common and urgent problem to be solved in order to accurately evaluate the reliability of grid-connected inverter. In this paper, the photovoltaic grid-connected system is taken as an example. The simulation models of photovoltaic cells and grid-connected inverters are established in the Matlab/simulink software. The DC voltage and AC current data of the inverter are obtained by measuring the solar irradiance and ambient temperature data. This paper provides data support for reliability modeling and calculation of the device. Then, the loss and thermal network simulation model of power device is built. The LESIT life prediction model based on failure physics is adopted, combined with rain flow counting method and fatigue cumulative damage theory. The damage calculation model of IGBT module is established, and the influence of power fluctuation, switching frequency and other factors on the device reliability is analyzed. The results show that the influence of various factors on the device is first reflected in the junction temperature change of the device, and the higher the satisfied temperature is, the higher the device reliability is. The low frequency junction temperature fluctuation caused by the lower reliability is the main factor that affects the reliability of the device. Changing the switching frequency can be used as a means to improve the reliability of the device. The strategy of improving the reliability of power devices by properly reducing the switching frequency in the full operation phase of the inverter is adopted. The strategy is simple and practical. And the reliability level of power device can be greatly improved. The failure rate of other devices except power device is calculated by using stress analysis method. On the basis of obtaining reliability data of each component, The average fault time of grid-connected inverter is calculated by using reliability block diagram method and Monte Carlo method respectively. The results obtained by the two methods confirm each other. The failure rate of each equipment in traditional distribution network reliability analysis adopts constant value. However, as a repairable system composed of multiple elements, the failure rate of inverter should change with the maintenance and renewal of internal components. Methods for calculating the reliability of equipment for equipment aging and device maintenance, The corresponding conclusions and the failure rate data of grid-connected inverter are given. This method has some engineering value both for the reliability research of active distribution network and for determining the repair period of grid-connected inverter itself.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM464;TM615

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