地区弱电磁环网合环潮流探讨

Power flow analysis of closing interconnection switches for weakly meshed networks in regional grid

浙江220kV电网分区运行之后,各供电路径上阻抗与潮流的不同导致110kV及以下电网合环开关两侧存在较大的相角差,合环潮流有可能引起设备过载甚至开关跳闸。目前杭州电网不同分区间合环操作普遍采用"先断后通"方式,操作过程中需短时停电,降低了供电连续性。根据地区电网环网规划,辐射运行的特点,经过分析计算给出了合环潮流经验公式,该公式通过系统等值阻抗建立起合环潮流与相角差之间的联系。据此原理设定的同期闭锁装置可以确保合环过程不致设备超载。该方法已在现场运用,效果良好,合环操作不再短时停电,并且对地区电网不同分区间的合环操作和降低地区电网合环潮流都有较强的指导意义。

Since the 220 kV power grid of Zhejiang Province gets zonalized, the different impedance and power flow on the 110 kV distribution line cause problems. That the large phase angle difference across the sectionizer, which connect two different 220 kV zones, leads to large loop current when the sectionizer is switch on. The equipment overload and even the switch trip may occur. Currently the method of 'opening breaker before connection' is applied for such kind of operation in Hangzhou grid. A short time outage is required in the process, which decreases the supply continuity. In this paper, the formula of sectionizer current is concluded from power flow analysis by establishing equivalent system impedance based on the radiant characteristic of regional grid. In addition, sychronized lock equipment is suggested to avoid overload. This equipment demonstrates good performance of 110 kV network connection without short time outage incurring. Further application could be developed for larger zone connection and loop current reducement.