基于潮流灵敏度的含UPFC电网有功环流控制

Control of Active Power Loops in Power System With UPFC Based on Power Flow Sensitivity

在含统一潮流控制器（unifiedpowerflowcontroller,UPFC）电网中,若存在潮流方向对UPFC有功设定值敏感的关键线路,可能引起有功环流。利用Floyd-Warshall算法确定关键线路,提出了其有功潮流与UPFC有功设定值间灵敏度模型,采用二阶求导确定两者间的单调性。基于牛顿法迭代修正灵敏度,求出每个环流回路中所有关键线路有功潮流为0对应UPFC设定值中的最大值,定义为回路临界值;将各回路临界值最小者作为UPFC有功设定值范围上或下限。算例结果表明,在运行点附近所定义灵敏度正负号不变,且二阶导数近似于0,所提算法是可行性的;UPFC安装位置影响有功环流位置,其控制方式影响有功设定值范围且正向/反向潮流大小可能不相等。所提算法有助于改善含柔性输电设备电网的潮流分布。

If there are the critical lines whose power flow directions are sensitive to active power setting of unified power flow controller（UPFC）, active power loops may be yielded. In this paper, Floyd-Warshall algorithm is applied to find the critical lines. A sensitivity model between active power flow of line and active power setting of UPFC is proposed, whose monotonicity is validated with the 2 nd order derivatives. The sensitivity is iteratively modified with Newton method to find critical loop flows, i.e. the maximum power flow settings of the UPFC corresponding to zero active power flow of all the critical lines. The minimum critical loop flows are set as the upper or lower limit of active power setting of the UPFC. Numerical results show that at given operation point, the sensitivity does not change sign, and the 2 nd order derivative approximates to zero, thus validating feasibility of the proposed model. The active power loops and active power setting range are affected by UPFC location and its control mode respectively. It is found that the forward/backward ranges may not be the same. The proposed models are useful to improve power flow distribution of the power system with flexible transmission equipment.