Power Converter Decentralized Specifications in Different Grid Nodes for DC Distribution Systems

Impedance-based methods are commonly applied to analyze the small-signal stability of grids with numerous power electronics converters (PECs). Due to the complexity of the grid, decentralized impedance specifications—allowing independent requirements for each PEC—offer significant advantages from the system operator's perspective, especially when PECs originate from multiple vendors. In fact, by applying decentralized specifications to the targeted PECs, the system operator ensures small-signal stability regardless of the specific control design of the PEC. The article extends the existing impedance specifications by developing a new approach to impose decentralized specifications on individual PECs connected to different grid nodes. This is obtained using the Gershgorin theorem to derive analytical conditions each PEC must satisfy. Since these conditions can be overly conservative, a combination of selected condition violations and impedance-based passivity criteria is proposed. Finally, the proposed approach is experimentally validated on a dc distribution system consisting of three dc–dc buck converters. The results demonstrate that instability can occur when the converters do not meet the specified requirements, whereas stability is maintained when the specifications are satisfied.