Abstract:

The advantages and disadvantages of various short-circuit current limiting methods were analyzed. According to the issue that the single-phase grounding fault current of 220 kV bus exceeded the limit in part of the 500 kV substations of the Guangdong Power grid, the principle of limiting fault current by installing small reactance at 500 kV autotransformer neutral point was researched. The analysis results show that the installation of small reactance is the effective measure for limiting asymmetric ground fault current, and the small reactance has the advantages of small investment, high economy and reliable operation. Through the calculation of short-circuit current of 500 kV Jalin station in 2015, the effect of installing 0 40 Ω reactance on limiting current was compared to suggest that the appropriate reactance resistance should be selected between 10 15 Ω. The installation of a small reactor has no impact on the normal operation of the system, but affects the sensitivity of zero-sequence protection device, therefore, the setting values should be re-checked to prevent protection from refusing to operate.

Key words: 500 kV substation, asymmetric short-circuit fault, short-circuit current, neutral point reactance