Single-ended DC Fault Location Method For MMC-Based HVDC Power System Using Adaptive Multi-step Levenberg-Marquardt Algorithm

This article presents an accurate DC fault location method that applies parameter fitting. This technique first discusses the traveling wave (TW) propagation process in the decoupled line-mode network. We obtain the exact fault distance equation based on the analytical expressions for the wavefront of backward line-mode voltage TW. The adaptive multi-step Levenberg- Marquardt's (AMLM) algorithm is used for parameter fitting due to its fast processing speed and accuracy. The exact fault location can then be estimated using the parameter fitting results. The proposed fault location method is validated using a three-terminal HVDC system modeled on a real-time digital simulator (RTDS) platform. Based on the experimental results, the proposed method accurately detects the fault location, with all estimated errors smaller than 1%, and can withstand 40 dB noise interference. Moreover, the proposed method does not need a high sampling frequency and communication device. Its accuracy is independent of fault resistance and type compared to existing methods.