电工技术学报2025，Vol.40Issue(7)：2226-2235,10.DOI:10.19595/j.cnki.1000-6753.tces.240411
换流变压器用有载分接开关过渡电阻温升的动态仿真
Simulation on Dynamic Temperature Rise of Transition Resistance in On-Load Tap-Changer Used in Converter Transformer
摘要
Abstract
The on-load tap changer is a core component of the converter transformer,mainly used to accurately adjust the voltage of the converter transformer,and thus stabilize the transmission of DC power.The on-load tap changer provides an extraordinary capacity of wide voltage regulation range and frequent operation.During the voltage regulation process,the circulating current flows through the transition resistance and generates high heat.The state of the transition resistance is crucial for the safety of the on-load tap changer in the converter transformer.Therefore,it is of great significance to clarify the temperature rise characteristics of transition resistance during the switching process of on-load tap changer for ensuring the safety of the ultra-high voltage direct current transmission system and power grid operation. In this work,an electrical-thermal coupling model was established using the COMSOL Multiphysics software and the temperature rise of the transition resistance of on-load tap changer in converter transformer was simulated under real operating conditions.The temperature distribution of the transition resistance is calculated under different workloads,revealing the temperature evolution of the transition resistance and its impact on temperature of the separate oil chamber during the switching process of the on-load tap changer.It was found that the surface temperature of the transition resistance firstly increases sharply in a zigzag pattern with the switching action of the on-load tap changer,and then slightly increases to a stable temperature,which was validated by temperature-measuring experiment of the transition resistance.By conducting research on the temperature rise of transition resistors under different load capacities,a model of the maximum temperature of transition resistors changing with load capacity was established.It was found that the maximum temperature rise during the transition resistor switching time series showed a linear relationship with load capacity.By further studying the temperature rise of transition resistors under different switching times and establishing a temperature rise evaluation model for multiple switching transition resistors,it was found that as the load capacity increases,the range of temperature fluctuations increases,and the temperature rise evaluation function of transition resistors can be fitted with an exponential function,providing theoretical guidance for the operation and maintenance of actual converter on load tap changers. The following conclusions can be drawn from the simulation analysis:(1)During continuous switching,the temperature curve of the transition resistance shows a serrated rise and tends to flatten over time.The average temperature of transformer oil slightly increases during the flow time period.(2)For the switching time sequence,the maximum temperature of the transition resistance under a certain load capacity can be predicted based on the model of maximum temperature changing with load capacity.It was found that a maximum of 12 MV·A load capacity can be allowed for complete timing switching.(3)For working conditions that exceed the number of switching sequences,the multi switching transition resistance temperature rise evaluation function can be used to predict the temperature rise of the tap changer after a large number of switching,thereby proposing the maximum allowable switching times of the on-load tap changer to reduce the verification work of tap changer development and testing personnel.关键词
换流变压器/有载分接开关/过渡电阻/温升仿真/有限元法Key words
Converter transformer/on-load tap changer/transition resistance/temperature rise simulation/finite element method分类
动力与电气工程引用本文复制引用
高煜,赵学童,李刚,汪可,杨丽君..换流变压器用有载分接开关过渡电阻温升的动态仿真[J].电工技术学报,2025,40(7):2226-2235,10.基金项目
国家重点研发计划资助项目(2021YFB2402100). （2021YFB2402100）
