中文摘要：

高压直流输电系统中，换流站晶闸管阀元器件的冷却至关重要。为了保证输电系统的正常运行，通常采用水循环冷却技术。以天广工程实际项目为背景，重点研究其冷却系统，对直流输电系统中的晶闸管水冷却单元进行建模仿真，考察冷却水的进水温度和流速对晶闸管冷却温度的影响，得出它们之间对应的关系曲线，为实际应用提供有价值的参考依据。

英文摘要：

It is very important to control the electronic component＇s temperature in HVDC converter station. In order to guarantee the normal operation of HVDC,the technology of water cycle cooling system is used. Based on TianGuang engineering project,the cooling system is researched as key point. The model of the thyristor water cooling unit of HVDC converter station is simulated, the influence of cooling water＇s inlet temperature and velocity on the cooling temperature of thyristor is investigated,and the corresponding relationship curve between them is concluded, which provides valuable reference for practical applications.