Small-signal stability analysis for the multi-terminal VSC MVDC distribution network; a review

The stable operation and control of the proposed terrestrial multi-terminal Voltage Source Converter (VSC) medium voltage DC (MVDC) distribution network is a remarkable motivation towards developing the future universal DC grid interconnecting the low voltage DC systems on one side and the high voltage DC systems on the other. The small-signal stability analysis are important in designing these power electronic based systems (PEBS). In this study, small-signal stability approaches for PEBS are reviewed with the aim of identifying suitable methods for the proposed MVDC distribution network. It is established that the impedance-based methods are suitable for local stability analysis complementing very well with the state-space modelling-eigenvalue analysis method best for global stability analysis. The Lyapunov linearisation method offers simple, adaptable, and accurate small-signal and large-signal stability study. On the other hand, the bifurcation analysis is an emerging non-linear approach with promising efficiency and precision. In conclusion, there is no single small-signal stability criterion that encompass an acceptable level of accuracy, adaptability, and efficiency. Thus, the impedance-based methods combined with state-space modelling-eigenvalue analysis, Lyapunov linearisation, and bifurcation theory can be suitable small-signal stability approaches for the multi-terminal MVDC distribution network.