Internal and external fault recognition method based on entropy of information for extra-high voltage (EHV) direct current electric transmission line

Abstract

The invention provides an internal and external fault recognition method based on entropy of information for an extra-high voltage (EHV) direct current electric transmission line. In the invention, the entropy of information is utilized to discover minute and transient difference in signals, so as to constitute criterions for the internal and external fault identification. After a fault is caused to the direct current electric transmission line, a promoter element is started, polarized wave voltage transient signals measured at a relay location conduct S-transform, and an analytical signal source is worked out; a probability distribution model is constituted through polarized wave voltage S-transform energy values; finally the entropy of information of the probability distribution model is worked out, and the internal fault and external fault are distinguished according to measurements of the entropy of information. A great amount of simulation results show the good effect of the internal and external fault recognition method.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to an information entropy-based method for identifying faults inside and outside the UHV DC transmission line. Background technique [0002] At present, traveling wave protection is widely used in the world as the main protection of HVDC transmission line protection. It uses the current and voltage traveling waves transmitted at the moment of fault to form ultra-high-speed line protection. Moreover, DC line protection provided by ABB and SIEMENS is adopted in most projects. Its protection is based on the current gradient, voltage traveling wave conversion rate and voltage traveling wave mutation as the criterion, but its protection is easily affected by transition resistance, especially when an external fault occurs, the fault traveling wave passes through the smoothing reactance at the end of the DC line If the voltage conversion rate of the inverter...

AI Technical Summary

Problems solved by technology

Its protection is based on the current gradient, voltage traveling wave conversion rate and voltage traveling wave mutation as the criterion, but its protection is easily affected by transition resistance, especially when an external fault occurs, the fault traveling wave passes through the smoothing reactance at the end of the DC line If the voltage conversion rate is reduced, it will easily cause protection malfunction or refusal to operate, which will have a great impact on the stable operation of the DC system.

Therefore, the main protection of the DC system based on the change rate criterion is easily affected by transition resistance, noise interference, fault distance, etc.

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