高压直流换流站阀厅屏蔽效能的研究

Study on the Shielding Effectiveness of HVDC Converter Valve Hall

为了控制换流阀的电磁骚扰对站内设备和邻近通信系统的干扰,在研究直流换流站阀厅的屏蔽效能中实测已投运的高压直流换流站阀厅屏蔽效能,同时还计算了不同结构金属网和金属板的屏蔽效能以对比分析。研究结果表明:采用彩钢板和金属网后的屏蔽效能约50dB,但实际换流站运行中阀厅屏蔽作用会降低,大约只有20dB;实际的阀厅屏蔽效果低于计算结果,特别在有引出线的穿墙套管处,计算结果完全不适用;若阀厅仅按6面体铺设直径6mm,网孔面积50mm×50mm的镀锌焊接钢丝网屏蔽层,足以满足要求;如采用0.6mm厚镀铝锌压型钢板,每隔30cm用铆钉连接,两板重合部分宽度>5cm,计算的单层板在<10MHz时,其屏蔽效能>40dB,实际中采用双层板,屏蔽效果更好。

In order to control the interference of electromagnetic disturbance from converter valve to equipments and adjacent communication systems, it is necessary to study on the shielding effectiveness of HVDC converter valve hall. The paper makes the measurements for the actual shielding effectiveness of some operating HVDC converter valve hall, and calculates the shielding effectiveness of metal mesh and metal plate with different constructions so as to compare with the actual effectiveness. Some conclusions could be obtained from the results： the shielding effectiveness is about 50dB with colour steel plate and metal mesh installed, but the actual shielding effectiveness would be reduced to 20dB. In fact, the shielding effect is not as good as the calculation result. The results are completely not applied especially for the shielding effect around the wall bushing with outgoing lines. It satisfies the requirements that the valve hall is wholly laid by the galvanized welded wire mesh shield with the diameter of 6mm and the mesh area of 50mm 50mm. If the aluminiumzinc-plated press formed steel plates with the thickness of 0.6mm and the width for the overlapped part greater than 5cm, are in riveted connection by every 30cm, the calculated shielding effectiveness of single layer plate up to 10 MHz is greater than 40dB. Actually, the double layer plate is adopted, and its shielding effectiveness is better.