周期电磁力下变压器绝缘垫块动态机械特性研究

Research on dynamic mechanical properties of transformer insulation pressboard under periodic electromagnetic forces

绝缘垫块的机械特性是变压器绕组结构建模的关键因素。运行变压器绕组受到周期电磁力作用,静态的应力-应变测试结果无法表征绝缘垫块的动态机械特性。针对周期电磁力下绝缘垫块的动态机械特性,本研究提出了一个非对称的滞回模型,该模型不仅包含线性的阻尼和刚度,还包含非线性的动态刚度。在实验中,利用气动激振器模拟电磁力的幅值和频率,获取不同压紧力下绝缘垫块的应力-应变数据,并利用基于NSGA-Ⅱ算法的多目标优化算法训练模型参数。结果表明:绝缘垫块的刚度和阻尼均与压紧力存在密切关系,且油浸垫块具有较明显的阻尼特征。随着压紧力的增大,加压和减压过程中绝缘垫块的动态刚度幅值减小。与周期电磁力的幅值相比,其频率对绝缘垫块机械特性的影响更显著。

The mechanical properties of insulation pressboard are key factors in modeling the structure of transformer windings.The operating transformer winding is subjected to periodic electromagnetic forces,and the static stress-strain test results cannot characterize the dynamic mechanical properties of insulation pressboard.In this paper,an asymmetric hysteresis model was proposed to study the dynamic mechanical properties of the insulation pressboard under periodic electromagnetic forces,and the model includes not only linear damping and stiffness coefficients,but also nonlinear dynamic stiffness.In the experiment,a pneumatic vibration exciter was used to simulate the amplitude and frequency of the electromagnetic force,and the stress-strain data of the insulation pressboards under different clamping forces was obtained.A multi-objective optimization algorithm based on NSGA-II algorithm was used to train the model parameters.The results show that the stiffness and damping of the insulation pressboard are closely related to the clamping force,and the oil-immersed pressboard has obvious damping characteristics.As the clamping force increases,the dynamic stiffness of the insulation pressboard decreases during the loading and unloading processes.Compared with the amplitude of periodic electromagnetic force,the frequency of periodic electromagnetic force has more significant effect on the mechanical characteristics of insulation pressboard.