高压自耦变压器肺叶磁屏蔽特性的数值计算与分析

针对一种新型的器身磁屏蔽——肺叶磁屏蔽自身以及其在变压器中的设计问题,以一台容量为334MV?A、带有肺叶磁屏蔽的单相自耦变压器为研究对象,首先应用三维频域非线性有限元法分析了肺叶磁屏蔽对变压器结构件、绕组区域漏磁场以及杂散损耗的影响;然后,以漏磁场分析以及杂散损耗计算为手段,以变压器油箱、夹件、拉板、油箱屏蔽以及肺叶磁屏蔽的磁感应强度(或损耗密度)作为观测目标,研究肺叶磁屏蔽安装位置以及尺寸对变压器漏磁场的影响,并通过负载损耗试验将有限元计算所得结果与实验值进行对比,验证分析的有效性;最后,针对肺叶磁屏蔽自身可能出现的局部过热问题,设计三种不同的肺叶磁屏蔽油路结构,基于有限体积法对比分析不同油路结构下肺叶磁屏蔽的油流、温升特性。对肺叶磁屏蔽特性的系统分析可为其设计以及其在变压器中的设计提供指导,具有重要工程意义。

Numerical Calculation and Analysis of Lobe-Type Magnetic Shielding in High Voltage Auto-Transformer

In this paper, a 334MV?A single-phase auto-transformer with lobe-type magnetic shielding is used as the prototype model, aiming at the design problem of a novel body magnetic shielding lobe-type magnetic shielding. Firstly, the influences of the lobe-type magnetic shielding on structure parts, leakage fields in windings and stray losses are examined using three-dimensional (3-D) non-linear frequency-domain finite element method (FEM). Taken the magnetic densities (loss densities) of tank, yoke clamp, tie plate, tank shielding and lobe-type magnetic shielding as the observation targets, the influences of lobe-type magnetic shielding location and size on the leakage fields of transformer are analyzed by the leakage field analysis and stray losses calculation. The load loss experiment has verified the analysis through comparing the calculation results with the experiments. Finally, three kinds of cooling oil models about lobe-type magnetic shielding are presented, regarding the local overheating problem on lobe-type magnetic shielding itself. The analysis of the lobe-type magnetic shielding characteristics provides important guidance and engineering significance of its own design in transformer.