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Commutation failure prediction method considering waveform distortion and DC current change

A DC current, commutation failure technology, applied in the direction of converting AC power input to DC power output, output power conversion devices, electrical components, etc., can solve problems such as lack of analysis from the perspective of mechanism

Active Publication Date: 2020-01-21
SOUTHEAST UNIV +1
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Problems solved by technology

However, most of the above methods measure the impact on the commutation process by formulating indicators related to influencing factors, lack of analysis from the perspective of mechanism, and have certain deficiencies in prediction accuracy and scene applicability

Method used

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  • Commutation failure prediction method considering waveform distortion and DC current change
  • Commutation failure prediction method considering waveform distortion and DC current change
  • Commutation failure prediction method considering waveform distortion and DC current change

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Embodiment Construction

[0050] Such as figure 1 As shown, the embodiment of the present invention provides a commutation failure prediction method considering waveform distortion and DC current change:

[0051] Step S1: Establish a mathematical model of the commutation process of the AC-DC system;

[0052] Step S2: collecting three-phase voltage data of the commutation bus;

[0053] Step S3: Calculate the Fourier expansion coefficients of the harmonics of each frequency of the three-phase voltage based on the discrete Fourier transform, and predict the commutation voltage during the commutation process;

[0054] Step S4: Predict the DC current in the commutation process based on the superposition theorem;

[0055] Step S5: Predict whether commutation failure occurs.

[0056] This embodiment takes the CIGRE HVDC benchmark model as an example for analysis, and its model structure is as follows figure 2 shown. The test system is built in PSCAD / EMTDC, the DC side voltage is 500kV, and the DC capaci...

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Abstract

The invention provides a commutation failure prediction method considering waveform distortion and DC current change for an AC and DC interconnection system. The method comprises the following steps:establishing an AC-DC system commutation process mathematical model according to a DC commutation principle; decomposing three-phase components of a converter bus voltage based on discrete Fourier transform, and predicting a commutation voltage in a commutation process; predicting a direct current of the commutation process based on the superposition theorem; finally, predicting whether commutation failure occurs or not by comparing the extinction angle prediction value with the inherent limit extinction angle of a valve. The method can quickly predict the occurrence of commutation failure after a system fault, facilitates the timely making and taking of emergency control measures, and is of great significance to the maintenance of the stable operation of a power system.

Description

technical field [0001] The invention relates to the technical field of power system situation awareness and trend prediction, in particular to a commutation failure prediction method considering waveform distortion and DC current variation. Background technique [0002] Due to its large capacity and low loss, the HVDC transmission system plays an important role in solving the problem of reverse energy load distribution. Commutation failure on the inverter side has always been one of the most common faults in HVDC transmission systems. Commutation failure will lead to a rapid drop in DC transmission power, which will cause a power impact on the AC system. At the same time, the drop in DC voltage and the increase in DC current will aggravate the DC magnetic bias of the converter transformer. When the fault is serious, it will cause continuous commutation failure or even successive commutation failure of adjacent DC, resulting in DC blocking and large-scale power loss, leading...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/36H02M7/00
CPCH02J3/36H02M7/00Y02E60/60
Inventor 汤奕张超明郑晨一刘福锁王玉
Owner SOUTHEAST UNIV
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