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Calculation method for strength judgment of hybrid system under UHVDC layered access mode

An ultra-high voltage DC, layered access technology, applied in computing, special data processing applications, instruments, etc., can solve problems such as unfavorable power flow evacuation of the receiving end system

Active Publication Date: 2017-11-24
SOUTHEAST UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

With the continuous increase of DC transmission capacity and the denser DC landing points, the existing DC access method will not be conducive to the power flow evacuation of the receiving end system, and will bring a series of problems in terms of voltage support and other aspects

Method used

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  • Calculation method for strength judgment of hybrid system under UHVDC layered access mode
  • Calculation method for strength judgment of hybrid system under UHVDC layered access mode
  • Calculation method for strength judgment of hybrid system under UHVDC layered access mode

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Embodiment 1

[0059] According to the above-mentioned critical short circuit ratio calculation method, the present invention provides the curve of layered critical short circuit ratio changing with layered power ratio, such as figure 2 shown.

[0060] From figure 2 It can be seen that with the increase of the power ratio between the 500kV layer and the 1000kV layer, the critical short circuit ratio of the 500kV layer continues to increase, and the critical short circuit ratio of the 1000kV layer continues to decrease, indicating that the greater the power allocated and accepted by the receiving end system of a certain layer, The greater the corresponding critical short-circuit ratio, the physical meaning is: the greater the power accepted by the receiving system, the greater its relative strength must be; the higher the arc-extinguishing angle setting value, the greater the corresponding critical short-circuit ratio.

Embodiment 2

[0062] 1. Calculation of delamination critical short circuit ratio

[0063] In the UHV DC layered connection mode, the rated layered power ratio is 1, and the arc extinguishing angle is generally set to 18°. Assume that the parameters of each converter station take the typical value S Tn =1.15P dNn , u kn %=0.18,τ n =1, can get C n =1.525, under rated operating conditions, the system has: γ n = γ N =18°, U i = 1, P dn = 1, I dn =1. It is possible to calculate μ Nn and constant K n , assuming that the reactive power consumed by the converter is all compensated by the AC filter and the parallel reactive power compensation device under the rated working condition, that is, take Q C1 =Q d1 +Q d4 , Q C2 =Q d2 +Q d3 . According to the calculation formula of critical short circuit ratio, it can be concluded that HCCSCR≈1.6 in this case.

[0064] 2. Calculation of layered boundary short circuit ratio

[0065] In general, the commutation angle of the 12-pulse convert...

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Abstract

The invention provides a calculation method for judging a strong or weak alternating current and direct current hybrid system in an ultra high voltage direct current hierarchical access mode. The method comprises the following steps: establishing a characteristic equation of the system according to an equivalent model of the alternating current and direct current system in the ultra high voltage direct current hierarchical access mode; providing the definitions of a hierarchical critical short circuit ratio and a hierarchical boundary short circuit ratio; calculating the critical short circuit ratio and the boundary short circuit ratio of the alternating current and direct current system; and judging that the hybrid system is strong or weak according to the relative magnitudes of the short circuit ratio, the critical short circuit ratio and the boundary short circuit ratio. The quantitative calculation method provides a good theoretical basis for stability research of the hybrid system in the ultra high voltage direct current hierarchical access mode, and has certain guiding significance for construction and operation of ultra high voltage direct current hierarchical access engineering.

Description

technical field [0001] The invention relates to a calculation method for judging the strength of an AC / DC hybrid system in an ultra-high voltage direct current layered access mode, and belongs to the technical field of ultra-high voltage direct current transmission. Background technique [0002] At present, the UHV DC transmission projects that have been built in China mainly adopt the multi-infeed single-layer access method. With the wide application of UHV AC and DC technology, multi-circuit DC centralized feeding into the load center of the receiving end will become a common phenomenon in my country's power grid. 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. The use of DC layered access technology in UHVDC transmission projects c...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J5/00G06F19/00
CPCG16Z99/00H02J5/00
Inventor 汤奕陈斌皮景创朱亮亮王琦李辰龙
Owner SOUTHEAST UNIV
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