The derivation method of the Jacobian matrix in voltage stability analysis of AC/DC power systems was systematically elucidated from the perspective of matrix elimination. The sign distribution property of the dominant modal sensitivity of the AC-side Jacobian matrix was utilized to qualitatively analyze the impact of different control modes of LCC-HVDC on the system voltage stability margin. Firstly, the Jacobian matrix derivation process under multiple LCC-HVDC control modes was uniformly expressed as the matrix elimination process of the fourth-order Jacobian matrix. Secondly, the complete proof of the sign distribution property of the dominant modal sensitivity of the Jacobian matrix in the AC Thevenin equivalent circuit was supplemented, based on which the change trend of the system stability margin at the receiving end AC system with different control modes was qualitatively analyzed. Finally, the effectiveness of the proposed method was verified by a Cigre standard system model. © 2023 Zhejiang University. All rights reserved.
