The increasing penetration of wind power may have a profound effect on the cascading dynamics of power delivery systems. In this study, we consider the impacts of packet traffic congestion, power overloading and network interaction on the failure evolution, and investigate the impacts of wind uncertainty and penetration level on the vulnerability of the cyber–physical power system to cascading failure. The proposed model takes into account the modularity of the coupled system, and incorporates both uncertainty analysis and stochastic approach into the line trip mechanism. The discrete packet traffic model is adopted to describe the influence of communication delay on the cascading failure of the power grid. Moreover, we investigate the effect of community structure on the robustness of the modular coupled system. Results indicate that increased wind uncertainty can lead to the occurrence of cascading events and higher wind power penetration increases the vulnerability of the coupled system to cascading failure. In addition, the robustness of the modular coupled system can be enhanced by dissolving the community structure of the communication network, and the timely and efficient data transmission in the communication network can make the cyber-coupled power system more robust.