Converters Control Roles Selection For Operating Hybrid Acdc Grids With Enhanced Small-Signal Stability Performance

In hybrid AC/DC grids, Interconnecting Power Converters (IPCs) can assume different control roles, mainly among grid-following and grid-forming. The various possibilities of roles assignment are in this study indicated as Converter Control Roles Combinations (CCRCs). Their number can become large, as it grows both with the number of considered control roles and the number of IPCs in the system. This adds complexity to the studies aimed at assessing the stability of hybrid AC/DC grids operation, as all the possible CCRCs have to be considered. This paper presents a methodology for selecting a subset of the feasible CCRCs that allows the operation of the system with enhanced small-signal stability performances. The use of data mining techniques is proposed. First, the CCRCs are clustered according to their stability behavior in the system operable region. Second, the discovered patterns are revealed explicitly by a knowledge extraction process. To exemplify the proposed methodology, a test system made of three AC sub-grids and two DC sub-grids is used and a small-signal stability performance indicator measuring the voltage deviation in the DC grids is considered.