College of Electrical and Electronic Engineering, Shandong University of Technology, Zibo 255000, China

With the widespread access of different power electronic equipment, the stability analysis of AC/DC distribution systems has become more complex, leading to low-frequency oscillation accidents which seriously endangered the safe and stable operation of the systems. How to simplify the complex AC/DC distribution system model and analyze the dynamic characteristics of DC voltage under different parameters is the key to improving system stability and avoiding system oscillation instability. This paper takes the three-terminal AC/DC distribution system as the research object. First, the equivalent single-machine model is established to achieve the equivalent order reduction of the multi-terminal AC/DC distribution system. Then, based on the equivalent single-machine model, a low-frequency analysis model of DC voltage is derived, which reduces the order of the low-frequency model and obtains an analytical expression of the dynamic performance of DC voltage. Thirdly, based on the transfer function and analytical expression of the equivalent single-machine model, a stability domain analysis method is proposed to study the influence of system parameter changes on the stability domain and system dynamic performance. Finally, based on the software simulation and hardware-in-the-loop experiments, the effectiveness of the proposed method is verified.

This work is supported by Shandong Provincial Natural Science Foundation of China (No. ZR2023ME034) and National Natural Science Foundation of China (No. 52377110).