A method for longitudinal protection of double-circuit transmission lines on the same tower based on T-type line equivalent and post-measurement simulation ideas

A technology of double circuits and transmission lines on the same tower, which is applied in the direction of the fault location and can solve problems such as difficulty in normal operation

Active Publication Date: 2015-09-30
KUNMING UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In particular, when this protection is used on long-distance UHV transmission lines, it will also be affected by the distributed capacitance current of the line, making it difficult to operate normally

Method used

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  • A method for longitudinal protection of double-circuit transmission lines on the same tower based on T-type line equivalent and post-measurement simulation ideas
  • A method for longitudinal protection of double-circuit transmission lines on the same tower based on T-type line equivalent and post-measurement simulation ideas
  • A method for longitudinal protection of double-circuit transmission lines on the same tower based on T-type line equivalent and post-measurement simulation ideas

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach 1

[0073] Implementation Mode 1: The wiring diagram of the simulation system is as follows figure 1 As shown, the voltage level is 500kV, the sampling frequency is 20kHz, and the sampling window length is 3ms. Assume that an AG fault occurs at a distance of 100km from the M terminal on the PM section of the line, the transition resistance is 10Ω, and the initial phase angle of the fault is 90°. The steps of the method for longitudinal protection of double-circuit transmission lines on the same tower based on T-type line equivalent and post-test simulation ideas are as follows:

[0074] (1) Convert the voltage and current at the head and end of the double-circuit transmission line on the same tower to independent moduli using the phase-mode transformation matrix, and establish the same-vector α-mode network of the double-circuit transmission line on the same tower based on the T-type equivalent of the lumped parameters. The phase mode transformation matrix used in the present inv...

Embodiment approach 2

[0089] Embodiment 2: The structure and parameters of the simulation system are the same as those in Embodiment 1. It is assumed that an AG fault occurs at a distance of 50 km from the M end of the line MN, the transition resistance is 10Ω, and the initial phase angle of the fault is 90°.

[0090] Repeat the steps of Example 1 to judge the fault section, and set the threshold ε to 0.2 through the simulation experiment, and then distinguish the internal and external faults of the double-circuit transmission line on the same tower by comparing the characteristic quantity of the criterion with the size of the preset threshold: Calculation Get δ=0.7202, if δ>ε is satisfied, it is judged that the protected line is faulty.

Embodiment approach 3

[0091]Embodiment 3: The structure and parameters of the simulation system are the same as those in Embodiment 1. It is assumed that an AG fault occurs at a distance of 100 km from the N terminal on the NQ section of the line, the transition resistance is 10Ω, and the initial phase angle of the fault is 90°.

[0092] Repeat the steps of Example 1 to judge the fault section, set the threshold ε to 0.2 through the simulation experiment, and identify the internal and external faults of the double-circuit transmission line on the same tower by comparing the criterion feature quantity with the preset threshold value: Calculation Get δ=0.0556, satisfy δ≤ε, and judge that the protected line has no fault.

[0093] Such as figure 1 The shown double-circuit power transmission system on the same tower uses the method of the present invention to simulate and verify different fault distances and different grounding resistances, and the results are shown in the table below. The results show...

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Abstract

The invention provides a same-tower double-circuit electric transmission line pilot protection method based on a T-type line equivalent and post-test simulation thought, and belongs to the technical field of alternating current electric transmission line relaying protection. The method comprises the steps of detecting and recording voltages and currents at the head end and voltages and currents at the tail end of a same-tower double-circuit electric transmission line, carrying out phase-mode transformation, obtaining mode components in the same vector, respectively simulating a mode current a and a mode current b, in the same vector, of a midpoint of the electric transmission line through a mode voltage, in the same vector, of the head end, a mode current, in the same vector, of the head end, a mode voltage, in the same vector, of the tail end and a mode current, in the same vector, of the tail end, enabling an integral value of a sum of the a and the b in a short time window to serve as a criterion characteristic value, and judging faults inside and outside a same-tower double-circuit electric transmission line area by comparing the criterion characteristic value with a preset threshold value. A large number of simulations indicate that the same-tower double-circuit electric transmission line pilot protection method based on the T-type line equivalent and post-test simulation thought is good in robustness and has good practicability.

Description

technical field [0001] The invention relates to a method for longitudinal protection of double-circuit transmission lines on the same tower based on T-type line equivalent and post-measurement simulation ideas, and belongs to the technical field of electric power system relay protection. Background technique [0002] Line longitudinal current differential protection is one of the main protections of UHV AC transmission lines. It uses channels to transmit the waveform of the current on this side and the signal representing the current phase to the opposite side. The protection on each side is based on the amplitude and phase comparison of the current on both sides. The result distinguishes whether it is an internal fault or an external fault. This kind of protection not only compares the magnitude of the current on both sides of the line, but also compares the phase of the current, requiring phasor comparison. When transmitting the current phasor at both ends, there are high ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/08
Inventor 束洪春田开庆张兰兰高利
Owner KUNMING UNIV OF SCI & TECH
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