POWER SYSTEM CONTROL

A method and apparatus allocating power reserves to deliver power to a power network or grid for balancing a frequency of the grid, comprises: obtaining flexibility or availability characteristics of each power reserve or store, obtaining an indexing value associated with power delivery by each power reserve, determining the power requirement of the network, assigning one or more of the power reserves to deliver power to the network, the power reserves assigned according to their flexibility characteristics, their indexing value and the power requirement of the network. The flexibility characteristic may be the availability of power over time from the power reserve. The indexing value may be a priority value according to cost of power from the reserve or the environmental impact of the reserve.