谐波环境下模块化多电平换流器子模块电容器的多场耦合分析及优化研究  

Multifield Coupling Analysis and Optimization Research of Modular Multilevel Converter Submodular Capacitors in Harmonic Environment

作　　者：曹轩赫 胡迪 张楚岩 张传升 孙昊[2] 邵涛[2] CAO Xuanhe;HU Di;ZHANG Chuyan;ZHANG Chuansheng;SUN Hao;SHAO Tao(School of Information Engineering,China University of Geosciences,Haidian District,Beijing 100083,China;Beijing International S&T Cooperation Base for Plasma Science and Energy Conversion,Institute of Electrical Engineering,Chinese Academy of Sciences,Haidian District,Beijing 100190,China;State Grid Anhui Electric Power Research Institute,Hefei 230022,Anhui Province,China)

机构地区：[1]中国地质大学(北京)信息工程学院,北京市海淀区100083 [2]中国科学院电工研究所等离子体科学和能源转化北京市国际科技合作基地,北京市海淀区100190 [3]国网安徽省电力有限公司电力科学研究院,安徽省合肥市230022

出　　处：《电网技术》2024年第10期4367-4376,I0127,I0126,共12页Power System Technology

基　　金：国家自然科学基金项目(U2166215)。

摘　　要：金属化薄膜电容器作为柔性直流输电用换流阀的核心设备,在大谐波分量与高环境温度的复杂多物理场作用下存在异常温升、鼓包形变等问题,严重影响着电容器的使用寿命。该文建立了金属化薄膜、电容器单体与电容器整机的电-热-力多场耦合模型,分析了模块化多电平换流器子模块常见谐波环境下,电容器内部多物理场特性。发现谐波电流增强了电容器层间电场畸变与金属化层的欧姆损耗,谐波电场的叠加增大了基膜的介质损耗,综合导致了电容热点温度与内部应力值在谐波分量的增大下呈指数形式上升。为改善电容器在谐波环境下的运行稳定性,采用多目标粒子群算法对单体电容的结构参数进行了优化,得到了单体结构最优解:膜厚4.7mm,膜宽41.8mm,电容直径40.6mm。优化后电容器内部电场畸变系数、热点温度与最大应力值分别降低了23%、22%与31%。提高了电容器在谐波环境下的工作性能,对提升其运行可靠性有一定的指导意义。Metalized film capacitors are the core equipment of converter valves in flexible DC transmissions.However,the abnormal temperature rise and bulge deformation problems under the multi-physics due to high harmonic interference and high ambient temperature seriously affect the capacitor's lifetime.This article establishes an electro-thermo-structural coupled model for metalized films,capacitor monomers,and the entire capacitor.The physical field characteristics of the capacitor were analyzed under the harmonic environment of MMC submodules.It is found that the injection of harmonic current enhances the interlayer electric field distortion and ohmic loss of the metalized layer in the capacitor.The superposition of harmonic fields increases the dielectric loss,resulting in an exponential increase of the hot spot temperature and internal stress with the increase of harmonic components.To improve the capacitor's operational stability under harmonic environments,the MOPSO algorithm was used to optimize the structural parameters of the capacitor monomer,and the optimal monomer structure was obtained:the film thickness is 4.7μm,width is 41.8 mm,and the diameter is 40.6 mm.After optimization,the internal electric field non-uniformity coefficient,hot spot temperature,and maximum stress of the capacitor were reduced by 23%,22%,and 31%,respectively,which effectively improved its working performance under harmonic environments and provided guidance for its reliability improvement.

关 键 词：金属化薄膜电容器 多物理场耦合 谐波特性 多目标优化 

分 类 号：TM721[电气工程—电力系统及自动化]