高压阀侧套管载流结构传热系统结构优化与试验验证

Structure Optimization and Test Verification of Heat Transfer System in Current Carrying Structure of HV Valve Side Bushing

随着我国特高压工程输送容量的提高,套管载流量逐渐升高,换流变阀侧套管的发热问题越来越严重,已成为制约其安全稳定运行的瓶颈。为解决特高压换流变阀侧套管研制中的短板问题,提出利用换流阀冷却水对阀侧套管进行强迫换热的热系统优化方法,开展了特高压换流变阀侧套管水冷式载流结构设计与优化,分析了传统±400 kV换流变阀侧套管的热场分布规律,优化设计了套管载流导杆的散热结构并提出了等效气隙热导率简化方法计算新型水冷套管热场分布,研究了水流速和电流幅值对水冷套管热场分布的影响。结果表明,随着电流幅值提升,水冷套管的载流导体和环氧芯体温度增加幅度远小于未采用水冷散热的阀侧套管;随着水流速度的提高,载流导体和环氧芯体的温度下降幅度逐渐减少,趋近于恒定值。研究表明,水冷式散热结构能大幅提高换流变阀侧套管的载流量和热裕度。

With the increase of transmission capacity in EHV projects in China,the carrying capacity of bushing is gradually increasing,and the heating problem of converter valve side bushing is becoming more and more serious,which has become the bottleneck restricting its safe and stable operation.In order to solve the problem of short plate in the development of EHV converter valve side bushing,this paper proposes a thermal system optimization method that utilizes the cooling water of the converter valve to perform forced heat exchange on the converter valve side bushing.The paper first carries out the design and optimization of water-cooled current carrying structure on the side bushing of EHV converter valve,analyzes the thermal field distribution law of the side bushing of the traditional±400 kV converter valve,and then optimally designs the heat dissipation structure of bushing current carrying guide rod and proposes a simplified method of equivalent air gap thermal conductivity to calculate the heat field distribution of new-type water-cooled bushing.Finally,the paper studies the influence of water velocity and current amplitude on the heat field distribution of water-cooled bushing.The results show that with the increase of the current amplitude,the temperature increase of the current carrying conductor and epoxy core of the water-cooled bushing is much smaller than that of the valve side bushing without water-cooled heat dissipation,and that with the increase of water velocity,the temperature drop of the current carrying conductor and epoxy core decreases gradually and approaches a constant value.The research demonstrates that the water-cooled heat dissipation structures can greatly improve the current carrying capacity and thermal margin of the side bushing of the converter valve.