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A key line identification method for cascading faults in AC and DC power grids

A technology for AC lines and key lines, which is applied in electrical digital data processing, special data processing applications, instruments, etc., and can solve problems such as insufficient consideration of the operating characteristics of DC lines.

Inactive Publication Date: 2017-11-28
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the above method is only suitable for pure AC systems. If the system contains a small number of DC lines, the above method performs AC line equivalents or other alternative methods for the DC lines, and does not fully consider the actual operating characteristics of the DC lines.

Method used

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  • A key line identification method for cascading faults in AC and DC power grids
  • A key line identification method for cascading faults in AC and DC power grids
  • A key line identification method for cascading faults in AC and DC power grids

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Embodiment 1

[0026] figure 1 It is a flow chart of the key line identification method for cascading faults of AC and DC power grids provided by the present invention. figure 1 Among them, the key line identification method for cascading faults of AC and DC power grids provided by the present invention includes the following steps:

[0027] Step 1: Calculate the weight value of each AC line in the AC-DC grid.

[0028] The weight value of the line refers to the reciprocal of the per unit value of the line reactance. Hypothesis α j is the weight value of line j, then the weight value of line j

[0029]

[0030] When reducing the per unit value of reactance, the reference voltage U B Take it as the rated voltage of the line, X j is the reactance of the line, the reference capacity S B Take 100MVA.

[0031] Step 2: After a DC line or AC line fault trips, perform transient stability calculations on the power grid.

[0032] Transient stability calculation means that on the basis of the...

Embodiment 2

[0071] Step 1: Adopt the modified CEPRI 36-node system, which includes 8 generators, 9 load nodes, 16 actual AC lines and 1 DC line. The network wiring diagram is as follows image 3 shown. The AC line and its parameters can be seen in Table 1. According to formula (1), the weight value of each line can be obtained, and the results are listed in Table 1.

[0072] Table 1: Line parameters and weight values ​​of the modified CEPRI 36-node system

[0073] Unit: Volt (V)

[0074] serial number

[0075] 7

[0076] It can be seen from the above results that the weight value of the line is related to the material (reactance) of the line itself and the rated voltage level of the line. Generally speaking, a line with a higher voltage level has a larger weight value; a line with the same voltage level has a smaller reactance and a larger weight value.

[0077] Step 2: Before the line is disconnected due to faults in the system, the power flow distribution of the s...

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Abstract

The invention belongs to the technical field of prevention and defense of cascading faults in electric power systems, and in particular relates to a key line identification method for cascading faults of AC and DC power grids, including: calculating the weight value of each AC line in the AC and DC power grid; calculating a certain DC line or AC line The transient stability process of the power grid after a fault trip occurs; calculate the amount of change in the transmission capacity margin of the surrounding lines caused by the active power of this fault line; calculate the correlation degree of the power flow transfer of this fault line to the surrounding lines; Calculate the line ratio by the ratio of the average value of the power flow transfer correlation degree of all lines in the power grid to the sum of the power flow transfer correlation degrees of the surrounding lines; obtain the ratio of all lines, and the line with the highest ratio is the line with the highest critical degree. It not only considers the power flow transfer during the occurrence of cascading faults, but also considers the operating characteristics of the DC system, and can conduct quantitative analysis on the criticality of all lines, which is of great significance for the prevention and control of cascading faults.

Description

technical field [0001] The invention belongs to the technical field of prevention and defense of cascading faults in electric power systems, and in particular relates to a key line identification method for cascading faults of AC and DC power grids. Background technique [0002] The special structure of the large-scale power grid determines the heterogeneity characteristics of the contact lines in the network in undertaking power transmission tasks. In the AC-DC grid, most of the DC lines and a small number of high-voltage AC lines have a high load level, which promote the propagation of cascading faults while ensuring the normal power transmission task of the grid. The failure of the high-load AC line may cause the commutation failure of the DC system converter with a short electrical distance, resulting in the blockage of the DC line; the blockage of the DC line will further cause the power flow distribution to change and cause the real power flow to be redistributed on ot...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06F19/00
Inventor 蔡万通刘文颖刘宇石叶湖芳李亚龙郭鹏朱丹丹夏鹏李慧勇梁安琪付熙玮魏泽田
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)