复合电场作用下换流变压器阀侧绕组绝缘特性研究
发布时间：2018-08-13 18:21
【摘要】：随着高压直流输电的迅速发展,换流变压器作为联接交流电网和直流线路的重要设备,绝缘问题是保证其可靠运行的关键。换流变压器与电力变压器有很大的不同,其承受的电压类型有稳态直流电压、工频交流电压、极性反转电压、雷电冲击电压和操作冲击电压。因此研究复合电场作用下换流变压器阀侧绕组的电场分布特性及影响因素对换流变压器的绝缘设计具有重大意义。本文根据实际±500kV换流变压器的绝缘结构,建立换流变压器结构模型,确定电场计算的数学模型,并给出相应的边界条件。首先利用有限元分析软件计算了换流变压器在稳态直流电压作用下电场,给出电场分布和最大电场强度值及出现的位置,分析得出影响电场分布的因素。其次计算了工频交流电压作用下电场分布,并与直流稳态电压作用下相比较,分析得出不同于直流电场的影响因素。计算交流电压叠加直流电压作用下电场分布时,采用交直流线性叠加的方法,得出电场分布特性及其影响因素。换流变压器承受的极性反转电压是与普通电力变压器最不同的特性。由于极性反转电压的特征,使绝缘介质出现非线性,本文研究了温度对绝缘介质非线性的影响。通过有限元数值计算方法与软件相结合对换流变压器的二维漏磁场模型进行了计算,将计算所得到的损耗值利用热源加载的方式施加在换流变压器的铁芯和绕组上,仿真得到换流变压器二维温度场分布情况,为分析考虑温度梯度影响时换流变压器在极性反转电压下的电场分布提供了依据。对换流变压器阀侧绕组在极性反转电压下进行仿真计算,得出内部电场的变化规律和电场分布的影响因素以及最大电场强度。由于温度对电阻率的非线性影响,对比分析未考虑温度影响和考虑温度影响时极性反转电场的分布,以及不同介质电场强度的变化趋势。本文得出的结论和研究方法,对换流变压器的绝缘分析及结构设计提供了依据和参考。
[Abstract]:With the rapid development of HVDC transmission, converter transformer as an important equipment to connect AC network and DC line, insulation is the key to ensure its reliable operation. Converter transformers are very different from power transformers. Their voltage types include steady-state DC voltage, power frequency AC voltage, polarity reversal voltage, lightning impulse voltage and operating impulse voltage. Therefore, it is of great significance to study the electric field distribution characteristics of converter transformer valve side windings and the influencing factors for insulation design of converter transformer under the action of complex electric field. According to the insulation structure of the actual 卤500kV converter transformer, the structural model of the converter transformer is established, the mathematical model of electric field calculation is determined, and the corresponding boundary conditions are given. Firstly, the electric field of converter transformer under steady DC voltage is calculated by using finite element analysis software. The distribution of electric field, the value of maximum electric field intensity and the position of occurrence are given, and the factors influencing the distribution of electric field are analyzed. Secondly, the distribution of electric field under the action of power frequency AC voltage is calculated, and compared with that under DC steady voltage, the factors which are different from DC electric field are analyzed. When calculating the distribution of electric field under the action of AC voltage and DC voltage, the characteristics of electric field distribution and its influencing factors are obtained by the method of AC / DC linear superposition. The polarity reversal voltage of converter transformer is the most different from ordinary power transformer. The influence of temperature on the nonlinearity of insulating dielectric is studied in this paper because of the characteristic of polarity reversal voltage. The 2-D flux leakage model of converter transformer is calculated by means of finite element method and software. The calculated loss value is applied to the core and winding of converter transformer by the way of heat source loading. The two-dimensional temperature field distribution of converter transformer is obtained by simulation, which provides a basis for analyzing the electric field distribution of converter transformer under polarity reversal voltage considering the influence of temperature gradient. Under the polarity reversal voltage, the variation law of internal electric field, the influencing factors of electric field distribution and the maximum electric field intensity are obtained by simulating the valve winding of converter transformer under the polarity reversal voltage. Because of the nonlinear effect of temperature on resistivity, the distribution of polarity reversal electric field and the change trend of electric field intensity in different medium are analyzed by contrast. The conclusion and research method provided basis and reference for insulation analysis and structure design of converter transformer.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM41
本文编号：2181802
[Abstract]:With the rapid development of HVDC transmission, converter transformer as an important equipment to connect AC network and DC line, insulation is the key to ensure its reliable operation. Converter transformers are very different from power transformers. Their voltage types include steady-state DC voltage, power frequency AC voltage, polarity reversal voltage, lightning impulse voltage and operating impulse voltage. Therefore, it is of great significance to study the electric field distribution characteristics of converter transformer valve side windings and the influencing factors for insulation design of converter transformer under the action of complex electric field. According to the insulation structure of the actual 卤500kV converter transformer, the structural model of the converter transformer is established, the mathematical model of electric field calculation is determined, and the corresponding boundary conditions are given. Firstly, the electric field of converter transformer under steady DC voltage is calculated by using finite element analysis software. The distribution of electric field, the value of maximum electric field intensity and the position of occurrence are given, and the factors influencing the distribution of electric field are analyzed. Secondly, the distribution of electric field under the action of power frequency AC voltage is calculated, and compared with that under DC steady voltage, the factors which are different from DC electric field are analyzed. When calculating the distribution of electric field under the action of AC voltage and DC voltage, the characteristics of electric field distribution and its influencing factors are obtained by the method of AC / DC linear superposition. The polarity reversal voltage of converter transformer is the most different from ordinary power transformer. The influence of temperature on the nonlinearity of insulating dielectric is studied in this paper because of the characteristic of polarity reversal voltage. The 2-D flux leakage model of converter transformer is calculated by means of finite element method and software. The calculated loss value is applied to the core and winding of converter transformer by the way of heat source loading. The two-dimensional temperature field distribution of converter transformer is obtained by simulation, which provides a basis for analyzing the electric field distribution of converter transformer under polarity reversal voltage considering the influence of temperature gradient. Under the polarity reversal voltage, the variation law of internal electric field, the influencing factors of electric field distribution and the maximum electric field intensity are obtained by simulating the valve winding of converter transformer under the polarity reversal voltage. Because of the nonlinear effect of temperature on resistivity, the distribution of polarity reversal electric field and the change trend of electric field intensity in different medium are analyzed by contrast. The conclusion and research method provided basis and reference for insulation analysis and structure design of converter transformer.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM41
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