A method of generating a power schedule for a wind turbine, the power schedule indicating how the turbine maximum power level varies over time, the method comprising: receiving input indicative of the maximum number of times that each of one or more turbine components are to be replaced over the remaining lifetime of the turbine; determining a value indicative of the current remaining fatigue lifetime of the turbine, or one or more of the turbine components, based on measured wind turbine site and/or operating data; receiving an initial predefined power schedule in respect of each of the wind turbines which specifies how the turbine maximum power level varies over time; and calculating an adjusted power schedule by varying a parameter of the initial predefined power schedule, by performing the following steps: i) adjusting the parameter of the initial predefined power schedule; ii) estimating the future fatigue lifetime consumed by the wind turbine, or one or more turbine components, over the duration of the adjusted power schedule, based upon the adjusted control schedule and accounting for the maximum number of replacements of the one or more turbine components; and iii) repeating steps (i) and (ii) until the estimated future fatigue lifetime consumed by the wind turbine or each of the one or more turbine components, based on the adjusted power schedule, is sufficient to allow a target minimum wind turbine life to be reached, thereby to calculate a determined power schedule; and providing the determined power schedule to a wind turbine controller to control the power output of the wind turbine. receiving input indicative of the maximum number of times that each of one or more turbine components are to be replaced over the remaining lifetime of the turbine; determining a value indicative of the current remaining fatigue lifetime of the turbine, or one or more of the turbine components, based on measured wind turbine site and/or operating data; receiving an initial predefined power schedule in respect of each of the wind turbines which specifies how the turbine maximum power level varies over time; and calculating an adjusted power schedule by varying a parameter of the initial predefined power schedule, by performing the following steps: i) adjusting the parameter of the initial predefined power schedule; ii) estimating the future fatigue lifetime consumed by the wind turbine, or one or more turbine components, over the duration of the adjusted power schedule, based upon the adjusted control schedule and accounting for the maximum number of replacements of the one or more turbine components; and iii) repeating steps (i) and (ii) until the estimated future fatigue lifetime consumed by the wind turbine or each of the one or more turbine components, based on the adjusted power schedule, is sufficient to allow a target minimum wind turbine life to be reached, thereby to calculate a determined power schedule; and providing the determined power schedule to a wind turbine controller to control the power output of the wind turbine. receiving an initial predefined power schedule in respect of each of the wind turbines which specifies how the turbine maximum power level varies over time; and calculating an adjusted power schedule by varying a parameter of the initial predefined power schedule, by performing the following steps: i) adjusting the parameter of the initial predefined power schedule; ii) estimating the future fatigue lifetime consumed by the wind turbine, or one or more turbine components, over the duration of the adjusted power schedule, based upon the adjusted control schedule and accounting for the maximum number of replacements of the one or more turbine components; and iii) repeating steps (i) and (ii) until the estimated future fatigue lifetime consumed by the wind turbine or each of the one or more turbine components, based on the adjusted power schedule, is sufficient to allow a target minimum wind turbine life to be reached, thereby to calculate a determined power schedule; and providing the determined power schedule to a wind turbine controller to control the power output of the wind turbine. i) adjusting the parameter of the initial predefined power schedule; ii) estimating the future fatigue lifetime consumed by the wind turbine, or one or more turbine components, over the duration of the adjusted power schedule, based upon the adjusted control schedule and accounting for the maximum number of replacements of the one or more turbine components; and iii) repeating steps (i) and (ii) until the estimated future fatigue lifetime consumed by the wind turbine or each of the one or more turbine components, based on the adjusted power schedule, is sufficient to allow a target minimum wind turbine life to be reached, thereby to calculate a determined power schedule; and providing the determined power schedule to a wind turbine controller to control the power output of the wind turbine.