电力工程技术 (Mar 2023)

A short-circuit current calculation method considering phase characteristics of wind power and photovoltaic and components between new energy units and grid

  • QIAO Li,
  • HUANG Zixin,
  • ZHANG Moucheng,
  • WEI Fanrong,
  • ZHAO Hongsheng,
  • LIU Ju

DOI
https://doi.org/10.12158/j.2096-3203.2023.02.028
Journal volume & issue
Vol. 42, no. 2
pp. 241 – 249

Abstract

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A large number of new energy units represented by wind power and photovoltaics are connected to the grid, making accurate calculation and verification of short-circuit current difficult. Given the phase mapping and the influence of electrical components (components between new energy units and grid) from the unit port to the grid-connected point, such as box transformer, collecting line, main transformer and transmission line are not considered when constructing the short-circuit current mapping model of new energy grid-connected point in the latest researches, an improved engineering grid short-circuit current calculation method that takes into account the phase characteristics of new energy sources and the influence of components between new energy units and grid is proposed. Firstly, combined with the national operation regulations, a supplementary theoretical modeling of the port voltage to short-circuit current phase mapping of new energy units is proposed. Secondly, the model is processed by engineering, and an iterative calculation method is proposed to extrapolate the obtained mapping back to the point of coupling. Then, the engineered short-circuit current amplitude-phase mapping model is applied to the existing local iterative calculation to obtain an improved calculation method. Finally, the new energy grid-connected model is built in the PSCAD simulation software to verify the accuracy of amplitude-phase mapping theory of new energy unit port voltage to short-circuit current and the effectiveness of iterative calculation theory of extra polating the unit port mapping model back to the point of coupling. On this basis, the mapping model is further verified by experiments in IEEE 39-node system. The results show that the proposed improved calculation method can improve the calculation accuracy of short-circuit current to a certain extent.

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