锥形绕组特快速暂态过电压分布研究

Investigation of Very Fast Transient Over-voltage Distribution in Taper Winding

为了研究在陡波前、高重复频率的电压冲击下,脉冲变压器(PT)锥形绕组中的特快速暂态过电压(VFTO)分布特性,建立了基于多导体传输线(MTL)理论的PT二次绕组分布参数模型;利用锥形绕组结构上的特性,提出一种有限元法(FEM)和插值公式相结合的方法以快速计算锥形绕组的感应系数矩阵K;通过求解频域下的电报方程可得到绕组的对地电压分布以及匝间电压分布;进行了绕组暂态电压的测量,从实验结果可以看出电压分布的一定规律,并分析了造成计算与实验结果间误差的原因;结合实验提出一种改善电压分布的措施,对大功率PT二次绕组的绝缘设计有一定的参考意义。

In order to study the very fast transient overvoltage（VFTO） distribution in taper winding of pulse transformer（PT） under high-frequency voltage surge of steep front, a distributed line model of PT＇s secondary winding is built based on multiconductor transmission line（MTL） theory. A new hybrid algorithm combining finite element method （FEM） and interpolation formulas is used to quickly evaluate the induction coefficient matrix K by utilizing some characteristics of the taper structure. The turn-to-ground and interturn voltage distributions can be obtained by solving the telegraphist＇s equations in frequency domain. Measurement work is done to investigate the voltage distribution inside the taper winding and thus to find some ways to weaken the voltage oscillations. Several factors result in the error between numerical and measured values. A method is validated through experiments that can decrease the maximum interturn voltage which may be very helpful to insulation design of PT＇s secondary winding.