A Time-Difference Longitudinal Protection Method for Half-Wavelength Transmission Lines

Abstract

The invention discloses a time difference longitudinal direction protection method for a half-wavelength power transmission line, and the method employs a local-side protection device and an opposite-side protection device. The method specifically comprises the following steps: calculating the time difference between a moment when the local-side protection device starts and a moment when the local-side protection device receives a start state of the opposite-side protection device; judging the position of a fault point according to the time difference, and carrying out the locked-type longitudinal direction protection operation to remove a fault when the fault point is located in a region or outside a region of 0-2400km or in a rear reverse direction; and carrying out the allowed-type longitudinal direction protection operation to remove the fault when the fault point is located outside the region or in a region of 0-2400km or on an opposite bus or a power transmission line at a next stage. The method employs the protection devices at two sides to detect the characteristic of the fault time difference when the half-wavelength line has the fault, and the time difference longitudinal direction protection proposed through combining with the reliability of a direction element can protect the whole line. A correct operation can be carried out after a fault in the region, and the operation is not delayed when a fault happens outside the region. Moreover, the method is higher in protection sensitivity.

Description

Technical field [0001] The invention relates to a time difference longitudinal direction protection method for a half-wavelength transmission line. Background technique [0002] Half-wavelength transmission lines are important transmission lines used in the construction of the energy Internet. Half-wavelength lines have long transmission distances. Compared with conventional lines, their fault characteristics are significantly different in space and time. On the spatial scale, the voltage along the line is nonlinear and Non-monotonic fluctuation characteristics; on the time scale, long transmission distance brings a long electromagnetic wave propagation and long channel delay, and there are significant differences in the moments of faults on both sides of the line. In terms of analysis methods, for half-wavelength transmission lines, the fault analysis method based on lumped parameters is not applicable, and the distributed parameter model needs to be used for analysis. In view o...

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art, provide a half-wavelength transmission line time difference longitudinal direction protection method, and solve the technical problems in the prior art that the fault protection of the half-wavelength transmission line is easy to malfunction and the protection sensitivity is not high

Images