A method for obtaining the strength of AC-DC hybrid multi-infeed DC receiving end power grid
A multi-infeed DC, AC-DC hybrid technology, applied in the direction of electrical components, can solve problems such as difficult to correctly distinguish the AC system, multi-infeed short-circuit ratio is not clear in physical meaning, and achieve the effect of clear physical meaning
Active Publication Date: 2017-05-03
ZHEJIANG UNIV
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Problems solved by technology
Although these methods can solve some problems caused by the multi-infeed DC short-circuit ratio, they have not fundamentally solved the problem that the physical meaning of the multi-infeed short-circuit ratio is not clear. Direct connection, but the multi-infeed short-circuit ratio definition does not have this property, making it difficult to correctly distinguish the strength of the AC system by using the multi-infeed short-circuit ratio index
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[0064] Establish a typical AC-DC hybrid multi-infeed DC system in Matlab software and DIGSILNET software, including two-infeed, three-infeed, and four-infeed systems. The specific DC systems used are all proposed by the CIGRE DC working group in 1991. standard model. The multi-feed system is obtained by its extension. The strength of the AC / DC hybrid multi-infeed DC receiving end power grid is judged by the method proposed in the present invention. Such as image 3 shown, where P 1 ,…P n is the DC transmission power, z 11 ,…z nn is the Thevenin equivalent impedance of the AC system at the receiving end.
[0065] Figure 4 The specific parameters of the standard model proposed by CIGRE DC working group in 1991 are given.
[0066] Figure 5-Figure 8 for the simulation results. Figure 5 is the variation of the virtual short-circuit ratio when the two-feed AC-DC hybrid multi-feed DC system reaches the static voltage stability boundary, Figure 6 When the two-infeed AC-...
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The invention discloses an alternating current / direct-current hybrid connection multi-infeed direct-current receiving end power grid strength obtaining method. The method includes the following steps that: a steady voltage stabilized limiting point bifurcating method is adopted to construct a system characteristic equation of a multi-infeed direct-current system; a direct current transmitting power diagonal matrix is obtained through power grid detection and is converted into an inverse matrix; an equivalent admittance matrix is obtained by a receiving end power grid through the Thevenin equivalence theorem; the inverse matrix and the equivalent admittance matrix are introduced into the system characteristic equation, so that the virtual short circuit ratio (VSCR) of the multi-infeed direct-current system can be obtained; and judgment is carried out according to the virtual short circuit ratio (VSCR) of the multi-infeed direct-current system, so that the strength of the multi-infeed direct-current receiving end power grid can be obtained. According to the alternating current / direct-current hybrid connection multi-infeed direct-current receiving end power grid strength obtaining method of the invention, a multi-infeed virtual short circuit ratio physical mechanism is clear and definite, and the strength of the alternating-current system can be accurately described. The alternating current / direct-current hybrid connection multi-infeed direct-current receiving end power grid strength obtaining method can be applied to alternating current / direct-current hybrid connection multi-infeed direct-current receiving end power grid strength judgment, so that an alternating current / direct-current hybrid connection multi-infeed system can operate stably.
Description
technical field [0001] The invention relates to a method for obtaining the strength of a receiving-end power grid, in particular to a method for obtaining the strength of an AC-DC hybrid multi-infeed DC receiving-end power grid. Background technique [0002] Due to the characteristics of energy and load distribution in my country, long-distance power transmission across provinces and regions has become one of the important challenges facing my country's transmission network. With its advantages in long-distance, large-capacity, and cross-regional power transmission, DC transmission has become one of the important methods for my country's "west-to-east power transmission and national networking". By 2020, there will be 38 direct current transmission lines in my country, mainly responsible for the task of sending southwest hydropower and northwest thermal power to the eastern load center and regional interconnection. These DC lines with relatively close electrical distances a...
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IPC IPC(8): H02J5/00
Inventor 辛焕海章枫
Owner ZHEJIANG UNIV