基于松弛变异系数的多微电网同调判定与等值建模

Homology Identification and Equivalent Modelling of Multi-microgrid Based on Relaxed Variation Coefficients

随着新能源的快速发展,分布式电源及微电网接入配电网的比例持续增加,配电网仿真研究变得更加困难。同调判定与等值建模是降低电网模型阶数的一种常用方法,已有不少研究利用同调理论对分布式电源进行等值建模。但现存分布式电源同调方法大多适用于下垂或虚拟同步控制,多控制方法下的电力电子器件通用同调识别方法尚未得到充分研究,多数分布式电源同调判定未考虑网络阻抗对同调性影响。在此背景下,提出了一种基于松弛变异系数的同调判定方法,该同调方法能综合量化多状态量子系统同调程度,且能更直观地体现各子系统的同调程度。首先,针对分群阈值确定困难的问题,提出了基于群内最大松弛变异系数曲线决定最佳分群数。然后,通过Kron化简对网络模型进行了进一步收缩。最后,通过IEEE 33节点配电系统改进算例验证了所提方法的有效性。

With the rapid development of renewable energy,the proportion of distributed generators and microgrids integrated into the distribution network continues to increase,and the simulation study of the distribution network becomes more difficult.Homology identification and equivalent modelling is a conventional method to reduce the order of the grid model.There have been many studies using homology theory to model the equivalence of distributed generators.However,most of the existing homology identification methods of distributed generators are suitable for droop or virtual synchronous control,and the universal homology identification method for power electronic devices under multiple control methods has not been fully studied.And most homology identification of distributed generators has not considered the impact of the network impedance on homology.Under this background,this paper proposes a method of homology identification based on relaxed variation coefficients,which can comprehensively quantify the homology degree of multi-state subsystems and more intuitively reflect the homology degree of each subsystem.First,to address the difficulty in determining the threshold of subgroups,this paper proposes to decide the optimal number of subgroups based on the maximum relaxed variation coefficient curve within the group.Then,the network model is further contracted by Kron simplification.Finally,the effectiveness of the proposed method is verified by an improved case of the IEEE 33-bus distribution system.