直流滤波电容器心子振动机理及特性研究  

Study on Vibration Mechanism and Characteristics of DC Filter Capacitor Core

作　　者：王亚琦 李琳[1] 崔建业 聂京凯 何强 王帅 WANG Yaqi;LI Lin;CUI Jianye;NIE Jingkai;HE Qiang;WANG Shuai(State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(North China Electric Power University),Beijing 102206,China;State Grid Zhejiang Electric Power Co.,Ltd.,Jinhua Power Supply Company,Jinhua 321000,China;Global Energy Interconnection Research Institute Co.,Ltd.,Beijing 102209,China)

机构地区：[1]新能源电力系统国家重点实验室(华北电力大学),北京102206 [2]国网浙江省电力有限公司金华供电公司,浙江金华321000 [3]全球能源互联网研究院有限公司,北京102209

出　　处：《电力电容器与无功补偿》2022年第6期1-10,共10页Power Capacitor & Reactive Power Compensation

基　　金：国家电网有限公司总部科技项目(521104170041)。

摘　　要：直流滤波电容器是高压直流输电换流站噪声的主要来源之一,因此有必要对其振动机理及特性进行研究。直流滤波电容器在交直流复合激励下,其心子内部电介质薄膜表面将产生极化电荷和弛豫电荷,同时介质薄膜表面还存在一定数量级的静电电荷。本文结合电容器工作时场路耦合模型,研究在直流电压分量存在的情况下,心子内部介质薄膜表面的极化电荷、静电电荷和弛豫电荷以及电容器金属极板上的自由电荷对电容器所受电场力的影响。以此为基础对一滤波电容器心子的振动特性进行了仿真计算与实验。结果表明:心子内部介质薄膜表面存在少量静电荷,在交直流激励稳定工作时,介质表面产生极化电荷和驰豫电荷,由于极化电荷是成对的,对于介质受力基本没有影响,驰豫电荷与静电荷分布在电介质薄膜上下表面,且上下表面电荷量相等,极性相反,导致介质受力平衡。电容器金属极板在交直流复合作用下将储存一定量的稳恒电荷和随时间变化的电荷,这两部分电荷在交变电场中使金属极板受力,致使心子的振动不仅包含激励电压交流分量基波和谐波频率的两倍频、和频和差频分量,还包含与激励电压交流分量基波和谐波同频的振动分量,且此同频振动分量的幅值与激励电压的直流分量呈线性关系。DC filter capacitor is one of the main noise sources in HVDC transmission converter station and it is therefore necessary to study its vibration mechanism and characteristics.Under the excitation of AC/DC composite excitation,polarization charge and relaxation charge will be generated on the surface of dielectric film inside the core of DC filter capacitor and,at the same time,there are a certain amount of electrostatic charges on the surface of dielectric film.In this paper,combined with the field circuit coupling model of capacitor in operation,the effects of polarization charge,electrostatic charge and relaxation charge on the surface of dielectric film inside the core and the free charge on the metal plate of capacitor on the electric field force of capacitor are studied in the presence of DC voltage component.On this basis,the vibration characteristics of a filter capacitor core are simulated and tested.The results show that there is a small amount of static charge on the surface of the dielectric film inside the core.In case of stable operation under AC and DC excitation,polarization charge and relaxation charge are generated on the dielectric surface.Since the polarization charge is a pair,it has basically no effect on the medium stress.The relaxation charge and static charge are distributed on the upper and lower surface of the dielectric film,and the amount of charge on the upper and lower surface is equal and the polarity is opposite,resulting in force balance of the medium.The metal plate of capacitor will store a certain amount of stable charge and time-varying charge under the combined action of AC and DC excitation.These two parts of charge force the metal plate to be stressed in the alternating electric field,causing the vibration of the core to not only include the double frequency,sum frequency and difference frequency component of the fundamental and harmonic frequency component of the excitation voltage,but also contain the same frequency vibration component of fundamental and harmonic componen

关 键 词：换流站 直流滤波电容器 极化电荷 弛豫电荷 振动特性 

分 类 号：TM53[电气工程—电器] TM721.1