A charging system (C-SYS) for charging at least one energy storage device (ESD) of a power grid (PG) according to a response curve (RC) indicating a power supplied by said energy storage device (ESD) to said power grid (PG) or absorbed by said energy storage device (ESD) from said power grid (PG) depending on at least one grid parameter of said power grid (PG), wherein in a dead band (DB) around a target value of said grid parameter a selected response curve (RC) is applied.