A power plant controller for generating a setpoint to a wind turbine generator connected to an electrical grid, wherein the setpoint relates to a desired amount of reactive power to be produced by the wind turbine generator, wherein the power plant controller comprises - a device controller (141, 142) configured to control operation of a reactive power regulating device (131, 132), wherein the reactive power regulating device is capable of injecting or absorbing an amount of reactive power to/from the electrical grid, - a reference control system configured to determine the setpoint on the basis of an electrical reference input and a measured electrical value, - a communication fault detector configured to detect a communication fault between the power plant controller and the reactive power regulating device, wherein - the power plant controller is arranged to be reconfigured in response to a detection of the communication fault in order to compensate the capability of the reactive power regulating device to inject or absorb the amount of reactive power to/from the electrical grid, wherein the power plant controller is arranged to perform the reconfiguration by any one or more of: - stopping the device controller (141, 142) to control operation of the reactive power regulating device (131, 132) in response to the detection of the communication fault, - reducing a maximum value of a limit function by a value determined from a capacity value of the reactive power regulating device, where the limit function is arranged for limiting the setpoint to the maximum value, - distributing the setpoint among other reactive power regulating devices (131, 132) not affected by the communication fault and/or wind turbine generators, and - changing a feed-forward modification value corresponding to the capacity of said reactive power regulating device by an amount corresponding to said capacity value of the reactive power regulating device or by reducing the feed-forward modification value to zero, where the power plant controller is configured to modify the setpoint by the feed-forward modification value. - a device controller (141, 142) configured to control operation of a reactive power regulating device (131, 132), wherein the reactive power regulating device is capable of injecting or absorbing an amount of reactive power to/from the electrical grid, - a reference control system configured to determine the setpoint on the basis of an electrical reference input and a measured electrical value, - a communication fault detector configured to detect a communication fault between the power plant controller and the reactive power regulating device, wherein - the power plant controller is arranged to be reconfigured in response to a detection of the communication fault in order to compensate the capability of the reactive power regulating device to inject or absorb the amount of reactive power to/from the electrical grid, wherein the power plant controller is arranged to perform the reconfiguration by any one or more of: - stopping the device controller (141, 142) to control operation of the reactive power regulating device (131, 132) in response to the detection of the communication fault, - reducing a maximum value of a limit function by a value determined from a capacity value of the reactive power regulating device, where the limit function is arranged for limiting the setpoint to the maximum value, - distributing the setpoint among other reactive power regulating devices (131, 132) not affected by the communication fault and/or wind turbine generators, and - changing a feed-forward modification value corresponding to the capacity of said reactive power regulating device by an amount corresponding to said capacity value of the reactive power regulating device or by reducing the feed-forward modification value to zero, where the power plant controller is configured to modify the setpoint by the feed-forward modification value. - stopping the device controller (141, 142) to control operation of the reactive power regulating device (131, 132) in response to the detection of the communication fault, - reducing a maximum value of a limit function by a value determined from a capacity value of the reactive power regulating device, where the limit function is arranged for limiting the setpoint to the maximum value, - distributing the setpoint among other reactive power regulating devices (131, 132) not affected by the communication fault and/or wind turbine generators, and - changing a feed-forward modification value corresponding to the capacity of said reactive power regulating device by an amount corresponding to said capacity value of the reactive power regulating device or by reducing the feed-forward modification value to zero, where the power plant controller is configured to modify the setpoint by the feed-forward modification value.