A large capacity self-commutated static VAr compensator rated at 31.5 MVA has been developed for the voltage flicker compensation. The operation experiences in an actual field and the successful performance of the voltage flicker suppression are introduced in this paper. The principle of the voltage flicker evaluation and the real time digital evaluation tool are also described. This tool can calculate simultaneously the voltage flicker value with and without the STATCOM. It can also analyze the voltage flicker from the arc furnaces which will be compensated by the STATCOM.