Stability Analysis of Hybrid AC/DC Power Systems for More Electric Aircraft

This paper presents the stability analysis of a hybrid AC/DC power distribution system, for embedded applications, particularly for more electric aircraft. In the studied system, a balanced AC source supplies the hybrid system, and a DC distribution system feeds multi-converter controlled loads. The load converters are tightly controlled, behaving as constant power loads with low damped LC input filters. An analytical model, taking to account the AC and DC characteristics of the system, is developed to investigate the dynamic behavior of the system. The AC system is modeled in a d-q synchronous reference frame. The stable and unstable operating points are identified using the proposed method, and then, the stability pattern of the system is established. The impacts of the constant power loads and interactions between the source and the load converters on the system's stability are studied. Experimental tests, conducted on a laboratory scale microgrid, validate the analytical system analysis.