A multi-model methodology for stability assessment of complex DC microgrids

The system stability is a paramount requirement to be attained in islanded DC microgrids. Even more crucial the obligation in MVDC shipboard power systems, where instability means ship blackout. The destabilizing interactions between high bandwidth controlled converters and LC filters are investigated to ensure the on board safe operation. Albeit the stability analysis is well-proven in case of few filtered power converters, the study becomes prohibitive in case of complex shipboard DC microgrids. To overcome this bottleneck, the paper defines a smart procedure to assess the small-signal stability in a multi-converter DC distribution, where several are the interacting controlled converters as well as the filtering stages. Basing on the Eigenvalues Based Method, the procedure can detect in advance the instability by analyzing nonlinear/linearized models, while the dynamics effect is testified on PSCAD switching simulations. A step-by-step comparison between the model's outputs can confirm the procedure validity, thus proving its capability in assessing the DC system stability.