روش عیب یابی تک بی انتها برای خط انتقال HVDC سگمنتال

This paper presents a single-ended traveling wave-based fault location method for segmented high voltage DC (HVDC) transmission lines; an overhead line combined with an underground cable. DC transient voltage and current signals at the sending-end of the overhead line are assumed to be available. Discrete Wavelet Transformation (DWT) is then applied to the DC voltage and current signals. The wavelet energies of voltage and current transients over 16 ms (i.e. 1-cyle in 60-Hz frequency) are calculated and then normalized. The normalized energies are used as the input to a binary Support Vector Machine (SVM) classifier for faulty section identification (underground cable or overhead line). Once the faulty section is identified, the faulty-half is determined by comparing polarity of the first two current traveling waves. Bewley diagrams are finally observed for the traveling wave pattern and the wavelet coefficients squared of DC voltage are used to locate the fault. The transient voltage and current for different fault locations are simulated using the ATP software. MATLAB is used to process the simulated transients and apply the proposed method. The performance of the proposed method is evaluated for different fault locations and fault resistances. The impacts of non-linear high impedance faults (NLHIF) and cable aging are also studied.