Controlling device and method for controlling power consumption in a system of power consuming devices

The invention relates to controlling power consumption of a group of plurality of groups of power consuming devices by determining power consumption control value for controlling power consumption of devices of the group by use of at least one of the following: load shedding flexibility value of at least one group of plurality of groups, wherein the load shedding flexibility value of the corresponding group indicates maximum amount of power, by which power consumption of devices of the corresponding group can be reduced such that minimum power consumption permissible in the corresponding group is maintained; load restoration flexibility value of the at least one group of plurality of groups, wherein the load restoration flexibility value of the corresponding group indicates maximum amount of power, by which the power consumption of devices of the corresponding group can be increased such that maximum power consumption permissible in the corresponding group is maintained.