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.
Highlights
High-voltage direct-current (HVDC) transmission systems have been widely applied to power transmission projects with long overhead transmission lines, bulk power and asynchronous interconnections because of their lower-cost transmission lines and larger power transmission capability [1,2]
A pilot protection method for HVDC transmission lines by using the directional features of voltage fault components and current fault components is presented in this paper
The directions of voltage and current fault components measured at both sides is extracted with the relative wavelet energy entropy
Summary
High-voltage direct-current (HVDC) transmission systems have been widely applied to power transmission projects with long overhead transmission lines, bulk power and asynchronous interconnections because of their lower-cost transmission lines and larger power transmission capability [1,2]. Their remote distance, complex surroundings and unpredictable weather conditions lead to a high failure rate, which requires protection methods with high reliability, fast response ability and sufficient sensitivity. High-resistance grounding leads to a fairly small current so that the current in characteristic frequency bands might be smaller than the setting value when a fault occurs. A protection system using one-end current would fail to operate
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