一种基于广域测量信息的在线同调分群方法

张艳霞 尹佳鑫 蒙高鹏 李杰 李多多

Abstract：In order to identify coherent generator groups quickly and accurately， two clustering indexes based on wide area measurement information are proposed. Firstly， the result of the pregrouping could be attained by calculating the effective values of the power angle difference among all the generators. Then， a similarity measure method called ρHsim was constructed by combining the Pearson correlation coefficient and the Hsim function. It considered the distance difference and the trend difference of the generator power angle trajectories at the same time， which can be applied to attain the result of furthergrouping. An improved clustering algorithm combining quality threshold （QT） clustering and kmeans clustering was proposed to meet the requirements of online recognition of coherent generators. The effectiveness of the proposed method is verified by the EPRI36 node system simulation example. Analytical results show that the generators with large power angle difference can be quickly assigned to different groups in the pregrouping stage by using the effective values of the power angle difference. In the furthergrouping stage， the result of coherency identification at different scales and levels of detail can be attained by using the new similarity measure index ρHsim.

Keywords：wide area measurement system; coherency identification; effective values of the power angle difference; correlation coefficient; Hsim function; quality threshold clustering; kmeans clustering

0 引 言

為了提高对大规模电力系统动态过程的分析效率，需采取有效方法对电网进行简化计算。目前对复杂电力网络的动态行为进行分析一般采用动态等值进行简化计算[1-3]。而应用最广泛的动态等值方法是发电机的同调等值法，该方法通过识别电力系统受到扰动后转子摇摆曲线相似的发电机，将其聚合成一台等值机，从而有效地简化系统，减少电力系统动态分析的计算量。此外，系统发生失步振荡时，解列控制技术是保障电力系统安全可靠运行的重要手段，而其前提就是准确快速地识别同调机群[4-5]。

同调识别的方法有很多，大体上可以分为基于模型参数的方法和基于发电机功角曲线的数据挖掘法。基于模型参数的方法主要包括电气距离法、状态空间法、慢同调法等。文献[6]引入电气距离衡量发电机间的紧密程度，并将其作为同调发电机的分群指标。文献[7]直接对系统的状态矩阵进行分析，进而给出了识别同调机群的方法。文献[8]通过构建系统的线性化模型，进而提出基于慢同调理论的发电机同调分群方法。以上方法都受系统模型精度的影响，通常难以应用于大型的电力系统，也无法考虑系统运行状态以及故障类型对同调分群的影响。

随着广域测量系统（wide area measurement system，WAMS）的出现和通信技术的发展，发电机动态受扰轨迹的获得变得容易，为基于发电机功角曲线的同调识别提供了数据支持，使得基于发电机功角曲线的数据挖掘方法得到了蓬勃发展。……