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A mmc-hvdc control strategy for auxiliary fault direction discrimination

A technology of MMC-HVDC and control strategy, applied in the field of MMC-HVDC control strategy, can solve the problem that the relay cannot correctly determine the fault direction, etc., and achieve the effect of easy digital realization, simple algorithm, and correctness

Active Publication Date: 2020-12-15
CHINA UNIV OF MINING & TECH (BEIJING)
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problem that the negative-sequence direction relay on the transmission line directly connected to the MMC-HVDC converter station cannot correctly determine the fault direction, the present invention provides an MMC-HVDC control strategy that assists in fault direction determination

Method used

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  • A mmc-hvdc control strategy for auxiliary fault direction discrimination
  • A mmc-hvdc control strategy for auxiliary fault direction discrimination
  • A mmc-hvdc control strategy for auxiliary fault direction discrimination

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Embodiment Construction

[0030] The present invention will be further described below in conjunction with the accompanying drawings.

[0031] Such as figure 1 , an MMC-HVDC control strategy that assists fault direction discrimination, including the following four parts:

[0032] The first part: Coordinate transformation and separation of positive and negative sequences.

[0033] Such as figure 1 , including the following steps:

[0034] Step (1): Sampling the three-phase AC voltage and current of the MMC-HVDC converter station to obtain the three-phase voltage u a , u b , u c and three-phase current i a i b i c ;

[0035] Step (2): Transform the three-phase AC voltage and current for 3s / 2s to obtain the αβ component of the voltage and current: u α , u β and i α i β ; The specific formula for the 3s / 2s conversion of voltage and current is as follows:

[0036]

[0037]

[0038] Step (3): The voltage αβ component u obtained by 3s / 2s transformation α , u β Separation of positive and ...

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Abstract

The invention discloses a modular multilevel converter type high-voltage direct-current power transmission (MMC-HVDC) project. After the project is accessed to an alternating-current power grid, a negative sequence direction relay on a power transmission line cannot correctly judge a fault direction and cannot correctly act. In order to solve problems, the invention discloses an MMC-HVDC control strategy assisting in fault direction discrimination. The strategy can assist the negative sequence direction relay to correctly and sensitively identify the fault direction on the basis of basically not influencing safe operation of the MMC, ensures the correct action of the relay, and ensures safety of operation of a power grid.

Description

technical field [0001] The invention relates to an MMC-HVDC control strategy for assisting fault direction discrimination, which belongs to the technical field of electrical engineering. Background technique [0002] Modular multilevel converter based HVDC (MMC-HVDC) has broad application prospects in the fields of asynchronous interconnection of power grids, offshore wind power grid integration, and power supply to cities, islands or remote areas. It has attracted extensive attention from academia and engineering circles. Since the State Grid Corporation of China put into operation the first MMC-HVDC project in my country in 2011, the DC transmission project using MMC as the converter has developed rapidly in my country. Up to now, there are as many as 8 MMC-HVDC projects in operation and under construction in my country, and the rated capacity and DC voltage have been increased from the initial 18MW, ±30kV to 5000MW, ±800kV. [0003] After an asymmetric fault occurs in t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/36H02J3/38H02M7/00
CPCH02J3/36H02M7/00Y02E60/60
Inventor 梁营玉李武林周毅斌赵创袁野刘旭武颖
Owner CHINA UNIV OF MINING & TECH (BEIJING)
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