A Transient Stability Analysis Method for Hybrid Power Transmission Systems with LCC-VSC

The line-commutated converter-voltage source converter (LCC-VSC) hybrid direct current grid becomes a new form, which is applied to high-voltage and long-distance power transportation. In this paper, a transient stability analysis method for LCC-VSC hybrid transmission systems is proposed, which considers the characteristics of AC/DC hybrid system transient stability analysis and calculates it through probability-based transient stability evaluation. Firstly, the stability analysis characteristics of the hybrid power transmission system are studied, and the hybrid HVDC transmission model at both ends of the LCC-VSC and the influence of the control mode on the transient stability are presented. Then the transient stability of AC/DC hybrid system is analyzed, and the selection method of system state before failure, the probabilistic stability fault model based on Monte-Carlo, and the probabilistic stability index solving method of power system are given. Finally, the rationality and effectiveness of the proposed method in the application of transient stability assessment of large power grid are verified through the analysis of a practical example of the power grid in China's “west-east power transmission” project.