Abstract:In view of the operation stability of the hybrid system of network structure and network connections in the off-grid operation state, this paper uses the state space small signal model to conduct in-depth stability analysis of the grid-following/grid-forming system. The analysis results reveal that under different trend directions, the stability of the hybrid system of the grid-following/grid-forming shows different trends. In order to accurately quantify and directionally analyze the specific impact of the trend direction on the off-grid operation stability of hybrid systems, this paper innovatively proposes stability analysis and evaluation indicators based on self-dissipation rate. Subsequently, through electromagnetic transient simulation experiments, the accuracy and reliability of the analysis results based on the self-dissipation rate index were verified. In addition, this paper also conducts a detailed analysis of the characteristic root participation factors of off-grid systems and traces the deep reasons that affect their stable operation, thus obtaining the specific trend of the impact of key parameters on system stability.