Stability Analysis and Dynamic Performance Evaluation of a Power Electronics-Based DC Distribution System With Active Stabilizer

The stability of dc microgrids is influenced by the nonlinear behavior of the converter-controlled loads with constant power characteristics. This nonlinear dynamic, in line with reduced size input filters used in the embedded power distribution of transportation systems, has a degrading effect on the dynamic performance and stability of the system. This paper presents the complete stability analysis of a dc distribution system composed of power electronics-based source and load. For this objective, a discrete-time dynamic model is developed and is applied to the studied system. Here, for the first time, the dynamic effect of the load controller is taken into the system model. In the studied system, the load converter is connected in cascade with the rest of the system, and is equipped with an input LC filter, representing a common distributed architecture for the transportation applications. The controller of the source converter employs an active stabilizer to extend the stability margin of the system. This stabilizer uses high-pass-filtered voltage of the dc bus following with a proportional compensator. The dynamic behavior of the controller and the stabilizer is experimented through a series of laboratory tests. Different load dynamics are implemented to demonstrate the impact of slow and fast load dynamics on the stability of the system.