Research On Short-Circuit Current Of Guangdong 500kV Power Grid

The expansion of installed capacity and the shrink of electric distance in power system, leading to a gradual rise in short-circuit current, which has been one of the serious problem in the future development of Guangdong power grid. In order to meet the long-term development of Guangdong power grid, the research on the short-circuit current of Guangdong 500 kV power grid has become an urgent need. The limiting measures of short-circuit current have been deeply studied in previous studies, but the affecting factors of short-circuit current have little quantitative analysis. In this paper, for the Guangdong 500 kV power grid, based on the short-circuit current calculation method of self-impedance and transfer impedance, proposed the concept of short-circuit current contribution factor, as the theoretical basis for the subsequent analysis and research.Firstly, the overall trend and the affecting factors of the short-circuit current of Guangdong 500 kV power grid have been analyzed. Based on actual data of Guangdong power grid from 2007 to 2014, the overall development level of the short-circuit current was calculated, and the increment of the short-circuit current of Guangdong power grid provided by installed capacity or network structure development in the "Eleventh Five-Year Plan " and the "Twelfth Five-Year Plan" were separately analyzed. Based on actual data of Guangdong power grid in 2014, the influence of AC interconnection between Guangdong and external power grid to the internal short-circuit current was analyzed, and with short-circuit current contribution factor, the contribution of power supply in different voltage levels and different areas were also analyzed.For the actual situation of Guangdong power grid, the limiting measures of short-circuit current adapted to Guangdong power grid were explored. The taken limiting measures of short-circuit current these years were classified, and then through the comparative analysis of the assumption with different power supply distribution schemes to get the recommendation of power supply access related in network planning. By solving ring and elongated connection line of two rings to get the implementable limiting measures of short-circuit current of network structure adjustment related in network planning.The existing schemes of long-term planning network structure were studied. The principle of short-circuit current control in each of the schemes were analyzed, and the difficulties and results of short-circuit current limiting were also compared. Considering short-circuit current limiting will do harm to the stability of power grid, a comprehensive assessment system based on analytic hierarchy process were established, which can compare the pros and cons of every scheme in various aspects, and ultimately make recommendations in choosing the long-term planning network structure proposal.