A method and apparatus for determining a DC short-circuit ratio of a layered DC system access

A DC system, DC short-circuit technology, applied in the direction of electrical components, etc., can solve problems that have not been related to research and application

Active Publication Date: 2018-12-14
CHINA ELECTRIC POWER RES INST +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional analysis based on the short-circuit ratio is a static method, and there is no relevant research and application on the short-circuit ratio of the AC-DC system with hierarchical DC access.

Method used

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Embodiment 1

[0080] Embodiment 1 of the present invention provides a method for determining the DC short-circuit ratio connected to a layered DC system. The specific flow chart is as follows figure 1 As shown, the specific process is as follows:

[0081] S101: Establish an equivalent node impedance matrix of the AC system;

[0082] S102: Calculate the short-circuit capacity of the converter bus in the layered DC system according to the equivalent node impedance matrix of the AC system established in S101;

[0083] S103: Determine the DC short-circuit ratio of the converter bus according to the equivalent node impedance matrix of the AC system established in S101 and the short-circuit capacity of the converter bus in the hierarchical DC system calculated in S102.

[0084] The above-mentioned layered DC system, AC system, and two-terminal DC system together constitute an AC-DC system. The layered DC system is connected to the AC system through commutation buses of different voltage levels, ...

Embodiment 2

[0103] Embodiment 2 of the present invention provides a device for determining the DC short-circuit ratio connected to a layered DC system, which mainly includes an establishment module, a calculation module, and a determination module. The functions of the above three modules are briefly introduced below:

[0104] Establishment module, mainly used to establish the equivalent node impedance matrix of the AC system;

[0105] The calculation module is mainly used to calculate the short-circuit capacity of the converter bus in the layered DC system according to the equivalent node impedance matrix of the AC system;

[0106] The determination module is mainly used to determine the DC short-circuit ratio of the converter bus according to the equivalent node impedance matrix of the AC system and the short-circuit capacity of the converter bus in the layered DC system.

[0107] The above-mentioned establishment module establishes the equivalent node impedance matrix of the AC system,...

Embodiment 3

[0125] Embodiment 3 of the present invention provides a method for determining the strength of an AC-DC system with DC layered access. The specific flow chart is as follows figure 2 As shown, the specific process of the determination method is as follows:

[0126] S101: Calculate the critical short-circuit ratio of the converter bus;

[0127] S102: Compare the DC short-circuit ratio of the converter bus determined in Embodiment 1 of the present invention with the critical short-circuit ratio of the converter bus calculated in S101 to determine the strength of the AC-DC system.

[0128] In the above S101, the specific process of calculating the critical short-circuit ratio of the commutation bus is as follows:

[0129] The critical short-circuit ratio of the converter bus is as follows:

[0130]

[0131] Among them, CSSCR i Indicates the critical short-circuit ratio of the converter bus i in the layered DC system, a, b, and t are all intermediate variables, and satisfy ...

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Abstract

The invention provides a method and a device for determining the DC short-circuit ratio of a layered DC system access. Firstly, an impedance matrix of an equivalent node of an AC system is establishedand the short-circuit capacity of a converter bus bar in the layered DC system is calculated. Finally, the DC short-circuit ratio of the converter bus is determined, which provides an important reference for the AC system planning. The invention is conducive to improving the voltage support capability of the layered DC system, guiding the important technical means of the power flow reasonable distribution of the power network, solving the voltage stability problem of the multi-feed DC system, promoting the coordinated development of the AC and DC power network, and has wide application prospect. The method and the device for judging the strength of the AC / DC system provided by the invention can be used for the planning and the operation of the layered DC transmission system, which is beneficial to the system planning, and the operators take effective control measures to improve the safe and stable operation level of the electric power system.

Description

technical field [0001] The invention relates to the technical field of power systems, in particular to a method and device for determining a DC short-circuit ratio connected to a layered DC system. Background technique [0002] With the widespread application of UHV AC and DC technology, it will become a common phenomenon in China's power grid to feed multiple DC circuits into the load center of the receiving end. With the continuous increase of DC transmission capacity and the denser DC landing points, the existing DC access methods will not be conducive to the evacuation of the power flow of the receiving end system, and will cause a series of problems in terms of voltage support and other aspects. In order to solve this problem, the DC layered access technology is used in the planned UHV DC transmission project, and the high-end converter and low-end converter of the UHV DC are respectively connected to the AC system of different voltage levels. Reactive equipment will a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J5/00
CPCH02J5/00
Inventor 林伟芳易俊汤涌孙华东卜广全郭强李柏青于钊贺静波王超
Owner CHINA ELECTRIC POWER RES INST
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