Research on a Short-Circuit Current Suppression Strategy for Multi-DC Receiving-End Power Grids Integrating Fuzzy Comprehensive Evaluation and Coordinated Optimization of Grid Structure and Current-Limiting Devices

To address excessive short-circuit currents and the pronounced “strong DC, weak AC” characteristic caused by large-scale UHVDC infeed into receiving-end grids, this paper proposes a planning-oriented suppression strategy integrating coordinated optimization of grid structure and superconducting fault current limiters (SFCLs) with fuzzy comprehensive evaluation. A coordinated model is first established to jointly determine discrete branch states and continuous SFCL equivalent series resistances while accounting for line-disconnection costs, equipment-investment costs, short-circuit-current limits, and physical-logical coupling constraints. A sensitivity-assisted Benders-type iterative framework is then developed, in which a mixed-integer master problem generates candidate planning decisions and a BPA-based subproblem performs nonlinear physical verification. Local finite-difference sensitivities are used to construct feasibility-guidance cuts rather than globally valid analytical Benders cuts. Physically feasible schemes are subsequently evaluated in terms of current-limiting effectiveness, steady-state voltage deviation, equipment-investment cost, and network loss. The method is validated using the modified CSEE-VS-66 system under standard and high-load operating conditions, a representative single-line-to-ground fault scenario, and an additional CSEE-FS-47 system. The results demonstrate that the proposed framework can provide physically feasible and economically balanced planning schemes without relying on a single performance indicator.