Abstract: Abstract:Due to that there is harmonic in power grid, the harmonic amplification may occur in parallel compensation capacitor of substation under certain operation mode. According to the configuration of the capacitor for the third main transformer of 500kV Yandu substation, the general process of parallel compensation capacitor design was proposed. Depending on the rational selection of the series reactance rate, the harmonic amplification in capacitor branch can be avoided, and it can be ensured that the overvoltage and the surge excitation current on the capacitor to be limited in permissible range. The allowed grouping switch mode of the capacitors in the substation with different series reactance rate was discussed too in this paper.

Key words: Key words:substation, power grid harmonic, parallel compensating capacitor, series reactance rate, harmonic amplifying, excitation surge current