双百万电力变压器绕组温度场及温升试验研究

发布时间：2018-11-09 11:02

【摘要】：近来,国内经济的高速运转使得各大工业的电力用量在剧烈增加,如何满足工业电力用电量,成为了国家电网下一步工作的重点,从而加快了特高压输变电技术的成长。其特点是容量大、传输距离远。特高压交流变压器是该技术变为现实的必备设备,在整个电力变压器领域中,该变压器技术含量高、制造难度大、各方面要求限制多。双百万变压器因为其技术复杂、容量大、电压等级为世界最高,因此带来的问题是其损耗大,对其温升的研究成为国内外电工装备业重点关注的问题之一。负载损耗作为变压器最主要的性能参数之一,由多个损耗分量组成。这些损耗均提供热源,热源的大小以及分布,都会直接或者间接影响变压器热点温升的分布。由于双百万变压器容量大,导致其尺寸也较大,为满足运输过程中的尺寸限制,导致了变压器单位损耗大,从而造成了内部散热较困难。所以该变压器进行设计面临的技术难题之一是,如何对绕组直阻产生的热量、冷却特性及绕组温升如何进行准确计算和分析。所以对双百万变压器不同工况下绕组内部的油流速度分布以避免油流带电,对绕组温度以及其热点分布特点进行研究和改进是非常有工程应用价值的,而温升及热点温升降低后,可明显提高变压器的绝缘寿命。在特高压变电站中,目前应用比较典型的是双百万(容量为lOOOOOOkVA、电压为1000000V)特高压电力变压器,简称为双百万变压器。本文就针对该双百万变压器的主体变的负载损耗的在各个线圈中各饼的分布、油流冷却结构及不同冷却器的工作状态、绕组以及热点温升问题进行了较深入的理论计算分析以及试验研究。首先,采用初步设计方案,基于美国SOFTTEAM公司开发的TranCalc集成计算软件,对该变压器绕组温升及热点温升进行了计算,对各绕组中热点温升超过限制的原因进行分析,针对具体情况,给出了解决措施。其次,研究了该变压器的油流结构,建立了三维流动模型,对不同冷却器对于整个变压器内部油流流动的贡献进行了分析研究,并提取了进入器身的平均流速为二维绕组的温升计算提供边界条件。再次,通过建立双百万变压器的二维绕组模型,利用大型商用CFD(计算流体动力学,Computational Fluid Dynamics)、传热学等的理论,应用流、固耦合的方法,对绕组内部流速以及温升进行了计算。最后,对双百万变压器温升试验接线原理以及试验过程进行了介绍。推过公式法和外推法对温升试验数据进行处理,并分别与不同软件计算的绕组温度梯度进行了对应的对比,并对其差异进行了说明,为后续深入研究奠定了基础。
[Abstract]:Recently, with the rapid operation of domestic economy, the power consumption of each major industry is increasing dramatically. How to meet the industrial electric power consumption has become the focus of the next step of the State Grid, thus speeding up the growth of UHV transmission and transformation technology. It is characterized by large capacity and long transmission distance. UHV AC transformer is the necessary equipment for this technology to become a reality. In the whole field of power transformer, the transformer has high technology content, high manufacturing difficulty and many requirements. Because of its complex technology, large capacity and the highest voltage grade in the world, the double million transformer has the problem of high loss, and the research on its temperature rise has become one of the most important problems in the field of electrical equipment at home and abroad. As one of the most important performance parameters of transformer, load loss is composed of multiple loss components. These losses all provide heat source, the size and distribution of heat source will directly or indirectly affect the distribution of transformer hot spot temperature rise. Due to the large capacity of double million transformer, its size is also large. In order to meet the size limitation in transportation process, the unit loss of transformer is large and the internal heat dissipation is difficult. Therefore, one of the technical problems in the design of the transformer is how to accurately calculate and analyze the heat generated by the direct resistance of the winding, the cooling characteristics and the temperature rise of the winding. Therefore, it is very valuable to study and improve the winding temperature and its hot spots distribution of oil flow velocity in the windings under different working conditions in order to avoid the oil flow electrification. However, the insulation life of transformers can be improved obviously after the decrease of temperature rise and hot spot temperature rise. At present, the typical application of UHV substations is double million UHV power transformers (lOOOOOOkVA, voltage 1000000V). In this paper, the distribution of each cake in each coil, the cooling structure of oil flow and the working state of different coolers for the main variable load loss of the double million transformer are discussed. The theoretical analysis and experimental study on the winding and hot spot temperature rise are carried out. First of all, based on the TranCalc integrated calculation software developed by SOFTTEAM Company, the temperature rise and hot spot temperature rise of the transformer winding are calculated, and the reason why the hot spot temperature rise exceeds the limit in each winding is analyzed. According to the concrete situation, the solving measures are given. Secondly, the oil flow structure of the transformer is studied, the three-dimensional flow model is established, and the contribution of different coolers to the oil flow in the whole transformer is analyzed. The average velocity of the inlet body is extracted to provide boundary conditions for the calculation of the temperature rise of the two-dimensional windings. Thirdly, by establishing the two-dimension winding model of double million transformer, using the theory of large-scale commercial CFD (computational fluid dynamics, Computational Fluid Dynamics), heat transfer, etc.), applying the method of flow and solid coupling, The internal velocity and temperature rise of the winding are calculated. Finally, the connection principle and test process of double million transformer temperature rise test are introduced. The formula method and extrapolation method are used to deal with the temperature rise test data. The results are compared with the temperature gradient calculated by different software, and the differences are explained, which lays a foundation for further research.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM41

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