A Method of Suppressing Unsymmetrical Short-Circuit Current

Abstract

The invention relates to a method for restraining asymmetric short-circuit current, which is used for restraining 220kV bus single-phase short-circuit current of a 500kV station in a 500kV / 220kV power grid system. The 500kV / 220kV power grid system comprises N transformation stations. The method comprises the following steps: (1) judging whether a 220kV bus of the 500kV station adopts a 3 / 2 wiring way or not, if so, switching to a step 3, otherwise turning to a step 2; (2) checking corrected single-phase short-circuit current, wherein the single-phase short-circuit current is obtained by subtracting minimum branch single-phase short-circuit current by the total single-phase short-circuit current ; and (3) optimizing and reducing the grounding points of the transformer stations. Compared with the prior art, the method has the advantages of capability of effectively restraining the single-phase short-circuit current, and higher running safety and reliability of a power grid system.

Description

technical field [0001] The invention relates to the technical field of power transmission and transformation, in particular to a method for suppressing an asymmetrical short-circuit current of a power grid based on selection of a main transformer grounding point. Background technique [0002] At present, the single-phase short-circuit current of the 500kV power grid in Shanghai mostly exceeds the three-phase short-circuit current, which is mainly caused by the grounding method of the DC converter transformer and the winding wiring method of the 220kV step-down transformer. The method used to solve this problem is to use the DC converter transformer Install a neutral point small reactance or a 500kV power plant step-up transformer to install a neutral point small reactance. However, this method can only affect the single-phase short-circuit current of nearby 500kV stations, and the scope of influence is relatively limited. The single-phase short-circuit current of most 500kV ...

AI Technical Summary

Problems solved by technology

However, this method can only affect the single-phase short-circuit current of nearby 500kV stations, and the scope of influence is relatively limited. The single-phase short-circuit current of most 500kV stations is still greater than the three-phase short-circuit current

Moreover, the 220kV busbars of some 500kV stations adopt a double-bus double-section structure, and the current distribution in the station is not the same as that of the 3 / 2 wiring. Therefore, in order to effectively suppress the single-phase short-circuit current and improve the flexibility of grid operation arrangement, it is necessary to correct the 220kV single-phase short-circuit current check method and suppression method

Images