An Incremental State Space Modelling Method of Power Systems Based on Measured Components Impedance Matrices in Local dq Frames

State space model (SSM)-based eigenvalues analysis method has been widely used to analyze stability issue of power electronics-dominated power systems. One important advantage of it is to perform participation factor analysis, so oscillation source can be identified. However, the derivation procedure of SSM is complicated for large-scale power systems. Furthermore, it’s not easy to obtain system SSM due to unknown internal structure and parameters. This paper presents an incremental state space modelling method of power electronics-fed power system based on measured components impedance matrices on local dq frames. Terminal impedance frequency responses of all components are first measured by frequency scanning method on local dq frames. Then, SSMs of all components are fitted according to the measured dq impedance matrices by matrix fitting algorithm. Finally, SSM series operator and parallel operator are used to aggregate the fitted components SSMs in a recursive way. Simulation results show that the proposed incremental state space modelling method needs not know components internal information. In addition, dynamics of all components can be preserved in the established system SSM, while the information is lost in the existing dq impedance matrices aggregation method. The proposed incremental state space modelling method is also applicable for both mirror frequency decoupled system and mirror frequency coupled system.