A Pilot Directional Protection for HVDC Transmission Line Based on Relative Entropy of Wavelet Energy

Abstract

Abstract:On the basis of analyzing high-voltage direct current (HVDC) transmission system and its fault superimposed circuit, the direction of the fault components of the voltage and the current measured at one end of transmission line is certified to be different for internal faults and external faults. As an estimate of the differences between two signals, relative entropy is an effective parameter for recognizing transient signals in HVDC transmission lines. In this paper, the relative entropy of wavelet energy is applied to distinguish internal fault from external fault. For internal faults, the directions of fault components of voltage and current are opposite at the two ends of the transmission line, indicating a huge difference of wavelet energy relative entropy; for external faults, the directions are identical, indicating a small difference. The simulation results based on PSCAD/EMTDC show that the proposed pilot protection system acts accurately for faults under different conditions, and its performance is not affected by fault type, fault location, fault resistance and noise.

Recognition of Traveling Surges in HVDC with Wavelet Entropy

“…When adopting wavelet entropy to analyze surges, the attenuation of traveling surges on transmission lines and the The entropy ratio of each wavelet decomposition level suggests the disorder of detailed wavelet coefficients in that frequency band. As shown in Figure 4, the largest entropy ratio of LD resides in levels 7 and 8, whose frequency band ranges from 9.765 kHz (5 MHz/2 8+1 ) to 39.06 kHz (5 MHz/2 7 ). This means the lightning strikes cause oscillations of the transmission system in such a frequency band.…”

“…A lot of research has discussed the discrimination of internal and external fault judgment with traveling surges. Various criteria are proposed and proved to be effective, for example, voltage/current differences (∆u and ∆i), the voltage/current change ratio (∆u/∆t and ∆i/∆t), or energy comparisons with different representations [1,[4][5][6][7]. However, for the recognition of internal faults, the major interference is a lightning surge.…”

Detection of high‐impedance fault in distribution network based on time–frequency entropy of wavelet transform

“…Then multilevel wavelet time Shannon entropy and multilevel wavelet time‐energy Shannon entropy are used to locate the sensor fault. In reference , the relative entropy of wavelet energy is used to distinguish internal fault from external fault of HVDC transmission system. Therefore, the wavelet transform combined with entropy theory provide a new solution for the data detection and classification .…”

Application of Shannon Wavelet Entropy and Shannon Wavelet Packet Entropy in Analysis of Power System Transient Signals

“…With the development of wavelet theory and entropy statistical theory, thanks to the fast development of high-speed A/D and DSP technology, SWE and SWPE are widely applied to the analysis and processing of transient signals in a power system, and their advantages have been unfolded. On the one hand, wavelet theory and wavelet packet theory are gradually improved and developed, and researches of algorithm structure and fast algorithm are deepened [8,9]. On the other hand, based on the advantages of wavelet theory and wavelet packet theory, they combine with entropy theory, which is developed toward practical direction [10][11][12].…”