Impedance-Based Modelling of Hybrid AC/DC Grids With Synchronous Generator for Interaction Study and Dynamic Improvement

•Impedance-based modelling of hybrid AC/DC grids with synchronous generator.•Interaction analysis between a synchronous generator and VSC.•Demonstration of required trade-offs in performance between generator and VSC.•Interaction mitigation and stability improvement in hybrid AC/DC grids. Hybrid AC/DC grids are increasingly been seen as the most important network structure for future transmission infrastructures. An emerging challenge to such grids is the constant interaction between various components in the system. Interactions could occur in many intricate forms including between and within the AC and DC subnetworks. However, considering the complexities involved, methods for detection that are intuitive, compact, and relatively straightforward to apply are lacking. In this paper, device-level closed-loop impedance models of subsystems in a hybrid AC/DC grid are extended compactly to subnetwork equivalents in the form of matrices. Then, interaction analysis between a voltage source converter (VSC) interconnected on both sides, and a synchronous generator with excitation control is carried out as a case study to highlight potentially detrimental interactions. The analysis is carried out in the frequency domain and validated with a nonlinear time domain simulations in MATLAB/SIMULINK.