Operational Risk Evaluation Model of Simplified Distance Protection

In order to ensure the safety of DC operation in UHV AC/DC hybrid receiving end power grid, a simplified setting method of distance protection is proposed in this paper, which gives priority to ensuring the rapidity and sensitivity of distance protection to remove faults. However, it may cause the loss of selectivity of distance protection and lead to the overstep tripping of AC power grid. To solve this problem, a risk assessment model and a risk grading system for simplified distance protection method are proposed. The effectiveness of the proposed method is verified by simulation analysis of a practical example of Shandong power grid.