Self-capacitance grading approach to suppress winding resonance in EHV transformers under oscillatory terminal disturbances

作     者：Shampa De Abhinandan De Gautam Bandyopadhyay 

作者机构：Department of Electrical EngineeringNetaji Subhash Engineering CollegeKolkataWest BengalIndia Department of Electrical EngineeringIndian Institute of Engineering Science and TechnologyHowrahWest BengalIndia 

出 版 物：《High Voltage》 (高电压（英文）)

年 卷 期：2018年第3卷第4期

页      面：310-315页

核心收录：

学科分类：1201[管理学-管理科学与工程(可授管理学、工学学位)] 0809[工学-电子科学与技术（可授工学、理学学位）] 080902[工学-电路与系统] 08[工学] 0823[工学-交通运输工程] 

主　　题：winding resonance capacitance 

摘      要：Interleaving of the high-voltage winding turns is a widely-accepted method for restraining the surge voltage stresses in extra high voltage(EHV)transformers.Reduction of voltage stresses under external surge is attributed by the increase in the self-capacitance of the interleaved winding disks.However,the apparent benefit of interleaving may be counterpoised by a significant decrease of natural frequency of windings,which in turn,may force a winding to resonate under external surges.Winding resonance is particularly noticeable when uniform interleaving is adopted for the whole winding,uniform interleaving attributes a unique natural frequency to all interleaved coils and consequently,the collective resonance of the winding disks is plausible.Uniform interleaving in large EHV transformers therefore leads to complications and the windings reportedly exhibit an unexpectedly poor surge voltage response because of such internal resonances.This study describes a novel concept termed as‘graded interleaving’for EHV transformer windings to overcome resonance and to achieve an improved response against surge voltage.The performance of the proposed winding was tested on a 132/33 kV two-winding transformer with a tap changer using EMTP(ATP)simulations with encouraging results.Manufacturing and real-time implementation feasibility of the winding were verified with transformer manufacturers.