Research On Propagation Characteristics Of Low Frequency Oscillation Based On Small-world Network

Modern power networks have become more and more complicated with the development of new energy equipment and smart grid.The complexity of the power network not only enhances the connection between the various regions,but also enables cascading failures to spread farther in the network and have a wider range of influence.Traditional reduction-based methods are difficult to establish accurate models for analysis with the complexity of components in the network.Complex network theory starts with the network topology to consider the impact on fault propagation.Low-frequency oscillation is one of the causes of cascading failure.Therefore,the study of the propagation process of low-frequency oscillations through complex network theory can analyze its influence from the perspective of network topology,and provide reference for the design of network topology and low-frequency oscillation suppression measures.Based on the complex network theory and the dynamic analysis of the Kuramoto-like model,this paper studies the propagation process of low-frequency oscillations based on the small-world characteristics of the network.Firstly,based on the graph theory and the Kuramoto-like model,the actual network is abstracted into a dynamic system that uses the unweighted undirected graph to represent the network topology and the phase equation to represent the dynamic behavior of different nodes in the network.A continuous sinusoidal form of perturbation is used to simulate one of the low-frequency oscillations.It is verified that the self-organized synchronism of the network without disturbance and the phase of each node after the disturbance is added will follow the disturbance at the same frequency.Secondly,based on the phase offset,the influence of the disturbance on the node is studied.Based on the two nodes and the simple chain and ring network,the propagation process of the disturbance in the system described by the Kuramoto model is studied.The effects of different parameters such as model and disturbance on the propagation process are analyzed.The numerical simulation analysis summarizes the conclusion that the phase deviation of the node will reach the maximum value under the combination of the coupling strength and the disturbance frequency.Then,the above two-node network is extended to a 500-node network to study the influence of two parameters of the small world characteristics on the disturbance propagation.Through the WS small world model,the influence of different reconnection probability p on the small world characteristic parameters of the generated network is analyzed.The constructed small world network studies the time used by the disturbance in the propagation process and the dynamic behavior of the node.Based on the results of numerical simulation,it is concluded that the speed of disturbance propagation is mainly determined by the average path length;and the distribution of phase deviation oscillation of nodes is mainly determined by clustering coefficients.Finally,the IEEE300 node is used to analyze and numerically simulate different situations,and the conclusions obtained are verified.