Fault Location of New Energy Transmission Lines Based on MultipleFrequency Signal Injection

To address the influence of converter control and transition resistance on traditional fault-location methods for renewable energy export lines, this paper proposes a single-terminal fault location method based on active injection of complex-frequency signals.Leveraging the controllability of a Static Var Generator (SVG), dual characteristic-frequency signals are injected immediately after fault occurrence.Stable injection is achieved through frequency-separation control and constant-current amplitude regulation.Equivalent fault topologies at the characteristic frequencies are established for both phase-to-phase and single-phaseto-ground faults, from which complex-valued distance equations are derived.Considering the long-line effects, a distributed-parameter model is further adopted to construct dual-frequency distance equations, and the Spider Wasp Optimizer (SWO) is introduced to achieve initial-value-independent fault distance estimation.Simulation results in PSCAD/EMTDC demonstrate that the proposed method exhibits strong robustness against transition resistance and is well-suited for highaccuracy fault location in renewable energy export systems.