Longitudinal differential protection method of power transmission line
A transmission line and longitudinal differential protection technology, which is applied to emergency protection circuit devices, electrical components, etc., can solve the problems of not adapting to the quick-moving requirements of longitudinal differential protection, low safety and stability of power system, and long calculation time of phasor method
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experiment example 1
[0162] Experimental example 1: Detection of normal working conditions inside and outside the transmission line
[0163] In the normal working state inside and outside the transmission line, the A-phase current value is collected and calculated, and a total of 40 points are sampled in each cycle, and the collected value and calculation of the first 10 points of the A-phase line current are taken The values are compared in Table 1 below:
[0164] Table 1 The normal situation of the structure inside and outside the line area
[0165]
[0166] It can be seen from Table 1 that when both the inside and outside of the transmission line are working normally, as the value of the unit number j increases, the calculated current value is closer to the collected value of the current, that is, the absolute error is getting smaller and smaller; When j=4, the relative error is less than 1%, and the accuracy is sufficient. Therefore, if the number of units is j=4, it can meet the accurac...
experiment example 2
[0167] Experimental example 2 Detection of the state of normal operation inside the transmission line and external short circuit
[0168] When the structure in the line area is normal and the A phase outside the area is short-circuited to ground, the current value of the A phase is collected and calculated, and a total of 40 points are sampled in each cycle, and the acquisition of the first 10 points of the A phase line current is taken The values and calculated values are compared in Table 2 below:
[0169] Table 2 The structure of the line in the area is normal, and the ground short circuit of phase A outside the area
[0170]
[0171]
[0172] It can be seen from Table 2 that in the case of a normal structure in the line area and a ground short circuit of phase A outside the area, as the value of the number of units j increases, the calculated current value is still closer to the collected value of the current , that is, the absolute error is getting smaller and ...
experiment example 3
[0173] Experimental example 3 Detection of the internal A-phase metal grounding short circuit of the transmission line
[0174] In the case of a metal-to-ground short circuit of the internal phase A of the transmission line, the current value of the phase A is collected and calculated, and a total of 40 points are sampled in each cycle, and the collected value and calculated value of the phase A line current of the first 10 points are taken Compare the table 3 below:
[0175] Table 3 Metal grounding conditions of phase A in the line area
[0176]
[0177] It can be seen from Table 3 that in the case of a metal-to-ground short circuit of the internal phase A of the transmission line, at this time, a major change occurs in the structure of the line area, and no matter what the number of units j is, the calculated current value is significantly higher or lower than Due to the collected value of the current, the absolute error is very large, and the relative error changes sign...
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