山东电网部分500 kV线路不平衡电流偏大原因的分析及改善措施的研究

针对山东电网部分500 kV线路的局部电流不平衡现象,通过仿真模拟了系统运行中的大(上午10:00)、小(凌晨3:00)潮流方式下的电流不平衡现象,并与电网运行中实测积累的大量不平衡电流数据进行比较,找出500 kV系统局部产生不平衡电流的原因是线路参数不平衡,即淄川-益都-潍坊同塔双回线路全线不换位及多条不平衡线路构成的2个环网,使个别线路在一定条件下产生了严重的不平衡电流。为改善该不平衡现象,对22种同塔双回线路的导线排列方式进行模拟计算分析,得出优化的导线排列组合方式。模拟计算结果表明,通过在变电站出线处合理调整同塔双回线路的导线排列方式,可有效改善山东500kV系统的局部电流不平衡现象。

Analysis on Oversize Unbalanced Currents in Part of 500 kV Transmission Lines of Shandong Power Grid and Corresponding Improvement Measures

In part of 500kV transmission lines of Shandong power grid the unbalanced currents are oversize. To find out the reason, the unbalanced currents under power flows of Shandong power grid at 10:00 (heavy load) and 03:00 (light load) are simulated respectively with EMTP software; simulation results are compared with a lot of actually measured data of unbalanced currents in these transmission lines during the power grid operation. Analysis results show that unbalanced parameters of 500kV transmission lines caused by whole-length un-transposed double 500 kV circuits on the same tower from Zichuan via Yidu to Weifang and the two ring networks composed by nine 500kV transmission lines are the main reason causing severe unbalance phenomena in individual transmission line. To improve such an unbalance phenomena, simulation and calculation of conductor arrangement ways for 22 kinds of double circuits on the same tower are carried out and optimized conductor arrangement ways are obtained. Results from simulation and calculation show that by means of rationally adjusting conductor arrangement way of double circuit on the same tower at the position where outlet of substation locates the partial current unbalance in Shandong power grid can be effectively improved.