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Measuring method for harmonic voltage on direct current side of high-voltage direct current power transmission system

A power transmission system, high-voltage direct current technology, applied in the direction of measuring current/voltage, measuring devices, measuring electrical variables, etc., can solve the problems of large harmonic measurement, high price, large volume, etc., and achieve high precision, simple operation, and high application value effect

Active Publication Date: 2013-10-23
ZHEJIANG JILONG POWER ELECTRONICS TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, among the currently used measurement methods and equipment for high-voltage harmonic voltage, the schemes of resistor and capacitor voltage division require special equipment, and these equipment are large in size and expensive.
It is the most convenient and economical method to use capacitive voltage transformers to measure high-voltage harmonic voltages. However, since the internal resonance conditions of capacitive voltage transformers under harmonic conditions will be destroyed, large errors will occur in the measurement of harmonics. Capacitive voltage transformers cannot be directly used for high-voltage harmonic measurement

Method used

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  • Measuring method for harmonic voltage on direct current side of high-voltage direct current power transmission system
  • Measuring method for harmonic voltage on direct current side of high-voltage direct current power transmission system
  • Measuring method for harmonic voltage on direct current side of high-voltage direct current power transmission system

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Embodiment 1

[0031] Step 1. Solve to obtain the current i flowing through the upper half branch ZH :

[0032] i ZH = Σ k = 1 n i ZLK - - - ( 1 )

[0033] Among them, i ZLk is the measured current of the kth parallel branch in the lower half branch, k=1,2,...,n;

[0034] Step 2. Due to the voltage u of each parallel branch of the lower half branch ZL It is the same, the current of any branch can be used to solve the voltage, and the current iZL1 of the parallel branch whose fundamental impedance is ZL1(1) in the following half branch is used as an example to illustrate: using Fourier transform technology, The measured current i ZL1 Perform harmonic decomposition:

[0035] i ZL ...

Embodiment 2

[0055] Step 1. Solve according to formula (1) to obtain the current i flowing through the upper half branch ZH ;

[0056] Step 2, for i ZH Carry out Fourier decomposition and solve the current i ZH The effective value of the hth harmonic of I ZH(h) and phase angle θ ZH(h) , h=1,2,...,m;

[0057] Step 3. Use the impedance-frequency characteristic curve of the DC side filter to find out the impedance amplitude Z of the DC side filter under the h order harmonic (h) and phase angle , combined with the I obtained in step 2 ZH(h) and θ ZH(h) Calculation of DC side voltage u of HVDC transmission system S The hth harmonic voltage of

[0058] For the designed DC filter, its impedance-frequency characteristic is a very important characteristic. It has been known at the time of design. The impedance-frequency characteristic gives the impedance amplitude and phase angle of the entire DC side filter at different The value at the harmonic frequency is plotted in the form of a cur...

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Abstract

The invention provides a measuring method for harmonic voltage on a direct current side of a high-voltage direct current power transmission system. The measuring method specifically comprises the following steps of: connecting a current transformer in series with a branch of a direct current side filter of the high-voltage direct current power transmission system; and calculating the harmonic voltage on the direct current side of the high-voltage direct current power transmission system by using the measured electric current in combination with each element parameter value of the direct current side filter or the known frequency-impedance characteristic of the direct current side filter. The measuring method is easy to operate and can be realized by only performing simple transformation on the basis of the conventional direct current side filter, the precision for measuring the harmonic voltage is high, the function of the direct current side filter is expanded, and the measuring method has higher cost performance; and the measuring method has extremely high application value and market promotion prospect on occasions for measuring the harmonic voltage on the direct current side of the high-voltage direct current power transmission system.

Description

technical field [0001] The invention relates to a method for measuring harmonic voltage on a direct current side of a high voltage direct current transmission system. technical background [0002] The DC transmission system has the advantages of low line cost, suitable for long-distance power transmission, no system stability problems, fast adjustment, and reliable operation. It is increasingly used in long-distance power transmission and AC system interconnection occasions. However, the converter station composed of power electronic devices used in the DC transmission system will generate a large number of harmonics, which will cause harmonic harm to the entire DC transmission system. Power supply departments and scientific research institutions urgently need to measure the voltage harmonics on the DC side of the HVDC transmission system to understand the voltage harmonics on the DC side of the HVDC system, formulate targeted harmonic control measures, and verify the DC sid...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R19/00
Inventor 黄银龙乐健毛涛罗汉武谭甜源
Owner ZHEJIANG JILONG POWER ELECTRONICS TECH