Comprehensive Small-Signal Modeling and Stability Analysis of Medium-Voltage AC/DC Distribution Networks Based on the Master-Slave Control Strategy

Abstract

As an effective solution for managing the access of distributed generations, medium-voltage AC/DC distribution networks are emerging as prospective forms of future distribution systems under the circumstances of increasing energy crisis and environmental pollution. Compared with the transmission systems, the medium-voltage distribution network has a lower voltage level, and the two-level voltage source converter (VSC) has become the preferred topologies for the interconnected converter. This paper proposes a comprehensive small-signal model for two-level-VSC-based medium-voltage AC/DC distribution systems, considering AC and DC distribution networks, AC filters, and all the controllers in the VSCs. The complex transformation between two dq coordinate systems in current studies is avoided based on the characteristics of dq transformation and discipline of the linearization. The impact of various control parameters on the small signal stability of the AC/DC distribution system is analyzed, and the feasible region of each parameter is obtained based on the small signal model proposed. Numerical calculations by MATLAB programming and electromagnetic transient simulations on PSCAD are compared. The results indicate that the small-signal mathematical model proposed in this paper can accurately represent the dynamic process of corresponding AC/DC distribution system, and the analysis of impact of parameters on small-signal stability can also be proved.