Combined traveling wave fault location method of high-voltage overhead line and cable hybrid line
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A technology of hybrid lines and ranging methods, applied in fault locations, information technology support systems, etc., can solve problems such as affecting fault location accuracy, complex traveling wave process, and accurately synchronizing line length errors, so as to improve power supply reliability, Broad application prospects and the effect of improving ranging accuracy
Inactive Publication Date: 2012-06-20
SHANDONG UNIV OF TECH
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However, in the overhead line-cable hybrid line, the traveling wave will be refracted and reflected at the connection between the overhead line and the cable, which makes the traveling wave process more complicated.
At the same time, due to the different wave impedances of overhead lines and cables, the propagation speeds of traveling waves in cables and overhead lines are very different.
Therefore, the traveling wave analysis of a single line and the various impedance ranging methods and traveling wave ranging methods that have been proposed are not suitable.
At present, the high-voltage overhead line-cable hybrid line fault location method based on the principle of double-terminal traveling waves is widely used. Since the distance measurement adopts the principle of double-terminal traveling waves, there are problems of precise synchronization of traveling wave devices at both ends of the line and errors in line length. affect the accuracy of fault location
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Embodiment 1
[0020] Example 1: Cable MP section length L C =20km, length of NP section of overhead line L O =35km, the propagation velocity of traveling wave in the cable v C =172.0920km / ms, the propagation velocity of traveling wave in the overhead line v O =295.0813km / ms. Assuming that the hybrid line fails at t=0, the fault point F is located in the MP section of the cable, and the distance from it to the M end is 5km.
[0021] Step 1. Fault segmentation: calculation
[0022] ΔT = L C v C - L O v O = - 2.3945 μs
[0023] Measured t M1 =30μs, t M2 =87μs, t N1 =205μs, t N2 =262μs, ΔT>t M1 -t N1 = -175μs, it is determined that the fault point F is located in the MP section of the cable.
[0024] Step 2. Initial test:
[0025] Calculate the possible distance from the fault point F to the M terminal according to the single-ended traveling wave principle:
[0026] D MF = v c ( t M 2 - t M 1 ) 2 = 4.905 ...
Embodiment 2
[0032] Example 2: Cable MP section length L C =20km, length of NP section of overhead line L O =35km, the propagation velocity of traveling wave in the cable v C =172.0920km / ms, the propagation velocity of traveling wave in the overhead line v O =295.0813km / ms. Assuming that the hybrid line fails at t=0, the fault point F is located in the MP section of the cable, and the distance from it to the N end is 25km.
[0033] Step 1. Fault segmentation: calculation
[0034] ΔT = L C v C - L O v O = - 2.3945 μs
[0035] Measured t M1 =149μs, t M2 =217μs; t N1 =86μs; t N2 =153μs, ΔTM1 -t N1 =63μs, it is determined that the fault point is located in the NP section of the overhead line.
[0036] Step 2. Initial test:
[0037] Calculate the possible distance from the fault point to the N terminal according to the single-ended traveling wave principle:
[0038] D NF = v o ( t N 2 - t N 1 ) 2 = 9.885 ...
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Abstract
The invention provides a combined traveling wave fault location method of a high-voltage overhead line and cable hybrid line. The method comprises the following steps of: firstly, carrying out fault section selection by using a double-ended principle according to time difference generated when a fault initial traveling wave of the hybrid line arrives at two ends, then carrying out initial fault location by using a single-ended principle, and finally working out an accurate result via the single-ended principle by combining with the time difference generated when the fault initial traveling wave arrives at two sides of the line. The method has the advantages that: the obtained fault location result is the result of the single-ended fault location principle, and the effects of hybrid line length error and accurate time synchronization problem of two sides of the line to the fault location accuracy are eliminated in the fault location by using the double-ended principle so that the accuracy and reliability of the fault location are improved. Therefore, the traveling wave fault location of the high-voltage overhead line and cable hybrid line is realized by using the method, the problem on how to accurately search a fault point position after the hybrid line is in the fault can be reliably solved and the traveling wave fault location method has a good application prospect.
Description
Technical field [0001] The invention belongs to the technical field of power system protection, and in particular relates to a combined traveling wave fault location method of a high-voltage overhead line-cable hybrid line. Background technique [0002] With the development of modern urban construction, the urban electricity load continues to increase. The existing overhead lines can no longer meet the needs of urban development, and the criss-crossing overhead lines also affect the overall image of the city. Therefore, the replacement of the original overhead line power supply by cable network power supply has become an inevitable trend in the development of urban power grids. With the continuous transformation and upgrading of urban power grids, urban cable networks have gradually developed to 110kV and above. Because the investment cost of high-voltage cables is quite high, most of the paths that can use overhead lines, generally do not use pure cable power supply, which resu...
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