Nodal Impedance Assessment in DC Power Distribution Networks

The evolution of the power electronics based energy sources and the dc transformer technology are enabling more complex and larger dc power distribution systems. For such a system, identifying the impedance characteristic of a certain node is an essential step to investigate the system’s stability and expansion capability. To address the challenges of multi-converter connections and bidirectional nodes, this paper investigates a method to approach dc power systems by computing a harmonic solution using the response for multiple degrees of freedom to determine the nodal impedances. It enables a scalable and straightforward procedure to compute each node impedance regardless of the system configuration. The solution is demonstrated for six nodes system with one dc transformer and it can be extended for any number of nodes and dc transformers. Theoretical developments are validated by means of simulations and the steady-state and impedance identification process is described in detail.