500kV架空地线金具发热的分析与对策

Analysis and Countermeasure of Hardware Heating for 500 kV Overhead Ground Wire

结合500 kV乔司变电站实测结果,分析架空地线接地方式对金具发热的影响。架空地线直接接地的接地环流是引起发热的主要原因,并带来输电损耗;采用分段绝缘单点接地虽然可以消除环流、降低损耗,但架空地线的感应电压高,在使用上有一定的局限性。针对这一问题,提出奇数段接地、偶数段换位的接地方式。利用500 kV双架空地线感应电压近乎反相的特点,通过换位策略中和架空地线的感应电压,减小了接地环流和输电损耗,换位后的架空地线分流系数变化不大,对跨步电压的影响不大,保证了安全性。

Combined with the actual measurement result of 500 kV Qiaosi substation, the impact of grounding mode of overhead ground wire on hardware heating is analyzed. The grounding circulating current brought by the direct grounding of overhead ground wire is the main reason of hardware heating and results in transmis- sion loss. Though the section insulation and Same point grounding method can eliminate circulating current and reduce the loss, there is high induced voltage on overhead grounding wire, which poses limitation to the use. Aiming at this problem, the method of odd number section grounding and even number section transposi- tion is proposed. By using the characteristic that the voltage phase of the double overhead ground wires is nearly opposite, the induced voltage of overhead grounding wire is neutralized through transposition strategy, grounding circulating current and transmission loss are reduced. The current sharing factor of overhead grounding wire after transposition changes little, bringing less impact on step voltage and ensuring the safety.