交直流混合系统潮流算法改进及其鲁棒性分析

提出一种改进交替求解法来计算交直流混合输电系统潮流。该方法克服了直流子系统计算过程中由于受到交流系统母线电压幅值的影响而可能产生振荡的缺点。采用牛顿拉夫逊法计算直流输电子系统中每个单元，避免依照公式直接计算可能产生对负数开方的问题；同时，它很好地处理了分接头的调整问题，克服了由于控制角的余弦值大于1而导致无法回算触发角(熄弧角)的问题。仿真结果表明该算法快速可靠。所提出的方法在南方电网不同断面、不同运行方式、以及系统N-1扫描的计算过程中，体现出较好的快速性和可靠性。

Revised Algorithm for AC/DC Power Flow and Its Robustness Analysis

This paper presents an improved advanced alternative iteration method to calculate the power flow of AC/DC systems.The presented algorithm solves the oscillation problem caused by voltage variations at AC buses during the power flow calculation for the DC subsystems. Newton- Raphson method was applied to calculate the power flow for each unit of DC sub-system to avoid the potential calculation of the root square of a negative value resulted from the charact- eristic equations of the converter. In the mean time, this new algorithm is able to effectively regulate the tap position of the converter transformer and solves the calculation problem of the control angle q? when cosq? is greater than 1. Digital simulation tests show that this method is fast and reliable.The power system data of China Southern Power Grid are used to examine the performance of the new algorithm for different system operation conditions, such as different cross-sections, different operation modes and “N-1” scanning, and the results show that the method presented is able to offer fast response and satisfactory reliability.