High-voltage direct current transmission line single-ended quick acting main protection method

Abstract

Disclosed is high-voltage direct current transmission line single-ended quick acting main protection method. The high-voltage direct current transmission line single-ended quick acting main protectionmethod mainly comprises the steps of A, collecting the outlet current ia(t) of a rectifier and the outlet current ib(t) of a direct current filter; B, performing wavelet decomposition and recomposition on rectified current of the latest 300 hours to obtain a subhigh-frequency-band-rectified wavelet decomposed current sum; C, performing wavelet decomposition and recomposition on filter current ofthe latest 300 hours to obtain a subhigh-frequency-band-filtered wavelet decomposed current sum; D, calculating the difference D(t) between the subhigh-frequency-band-rectified wavelet decomposed current sum and subhigh-frequency-band-filtered wavelet decomposed current sum to obtain the mean subhigh-frequency-band current difference of the latest 100 hours; E, if the mean subhigh-frequency-band current difference is higher than a set value D<set>, performing line main protection action, else, performing no action. The high-voltage direct current transmission line single-ended quick acting main protection method can be higher and more accurate in main protection action.

Description

technical field [0001] The invention relates to a single-end quick-acting main protection method for a high-voltage direct current transmission line. Background technique [0002] The reverse distribution characteristics of my country's primary energy and power load determine that high-voltage transmission will occupy an increasingly important position in my country's power grid structure. In high-voltage transmission, compared with high-voltage AC transmission, high-voltage direct current transmission has constant voltage, no skin effect, greater transmission power, and better economic benefits, making it stand out in long-distance power transmission. At present, China Power Grid has built and put into operation 29 high-voltage DC transmission projects, including 7 ±800kV UHVDC transmission projects, forming a large-scale "West-to-East Power Transmission" and "North-to-South Power Transmission" energy allocation pattern. By 2020, the transregional and transnational power g...

AI Technical Summary

Problems solved by technology

Actual engineering operation experience shows that the existing traveling wave main protection scheme has certain defects: 1) traveling wave protection cannot act on high-impedance grounding faults in the area where the remote grounding resistance of the line is greater than 100Ω; 2) traveling wave protection will Misoperation of non-high-resistance ground faults outside the area, especially metallic ground faults

The reasons for its refusal and malfunction are as follows: When a remote high-resistance grounding fault occurs in the area, due to the large grounding resistance and the long distance of the fault, the electrical parameters used in the calculation of traveling wave protection (traveling wave head voltage, current variation and rate of change) ) in the time domain is significantly reduced, so that the main action criterion cannot be satisfied, and the main protection action cannot be carried out; and when an external metallic ground fault occurs, the calculated value of the traveling wave protection will satisfy Criterion of protection action, main protection maloperation in the area occurs

Therefore, the traveling wave main protection cannot correctly distinguish the high-resistance ground fault in the far-end area of ​​the line from the metallic ground fault outside the remote area, and its reliability is low

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