From the perspective of state fragility and structural fragility, a comprehensive identification method of fragile branches is proposed. Taking into account the impact of direct current (DC) and renewable energy on the node voltage, the node coupling index and the improved trajectory sensitivity index are introduced to screen the weak voltage nodes. A multi-attribute decision-making model is established, considering the strength of the grid, the degree of voltage transient overruns and economic factors. This model not only can propose strengthening schemes on the basis of identifying the fragile links, but also can use dynamic reactive power equipment to compensate and improve transient voltage instability. Finally, a 37-bus system in Northwest China is used to verify the effectiveness of the method.

fragile branch, node coupling index, improved trajectory sensitivity, voltage transient over-limit, dynamic reactive power compensation