Wind power plant having a plurality of wind turbine generators and a power plant controller

1. A wind power plant, comprising:

a plurality of wind turbine generators; and

a power plant controller arranged to communicate with the plurality of wind turbines generators; wherein

each wind turbine generator in the plurality of wind turbine generators being related to a wind turbine controller, the wind turbine controller being arranged to control an active power output in its related wind turbine generator according to an active power set point received from the wind power plant controller;

the wind power plant supplies power to a utility grid in accordance with an active power reference;

such that upon a change in the active power reference the active power set point for each wind turbine generator is changed by a weighting factor;

wherein the weighting factor for an increase of the active power reference comprises a coefficient based on an available active power of each wind turbine generator relative to an available active power of the wind power plant, and

wherein the weighting factor for a decrease of the active power reference comprises a coefficient based on a produced active power of each wind turbine generator relative to an aggregated active power output of the wind power plant.

2. The wind power plant according to claim 1 wherein the weighting factor is different for each wind turbine generator.

3. The wind power plant according to claim 1 wherein the available active power is determined by each wind turbine generator and forwarded to the power plant controller.

4. The wind power plant according to claim 1 wherein change in the active power reference is set by a transmission system operator, a wind power plant owner or a wind power plant operator.

5. The wind power plant according to claim 1 wherein the weighting factor further depends on a rated power of each of the wind turbine generators.

6. The wind power plant according to claim 1 wherein the weighting factor further depends on an estimated wear of each wind turbine generator.

7. A method for operating a wind power plant which supplies power to a utility grid in accordance with an active power reference, the wind power plant comprising a plurality of wind turbine generators and a power plant controller arranged to communicate with a wind turbine controller of each of the plurality of wind turbine generators, wherein each wind turbine generator outputs active power in accordance with an active power set point received from the power plant controller, the method comprises the steps of:

receiving a change in the active power reference,

changing an active power set point of each wind turbine generator dependent on a weighting factor, wherein

the weighting factor for an increase of the active power reference comprises a coefficient based on an available active power of each wind turbine generator relative to an available active power of the wind power plant, and

the weighting factor for a decrease of the active power reference comprises a coefficient based on a produced active power of each wind turbine generator relative to an aggregated active power output of the wind power plant,

dispatching the changed active power set point to the wind turbine controller of each of the plurality of wind turbine generators, and

outputting, from each wind turbine generator, production power in accordance with the active power set point.

8. The method according to claim 7 wherein the weighting factor is different for each wind turbine generator.

9. The method for operating a wind power system according to claim 7 , wherein the available active power is determined by each wind turbine generator and forwarded to the power plant controller.

10. The method for operating a wind power system according to claim 7 , wherein change in the active power reference is set by a transmission system operator, a wind power plant owner or wind power plant operator.

11. The method for operating a wind power system according to claim 7 wherein the weighting factor further depends on a rated power of each of the wind turbine generators.

12. The method for operating a wind power system according to claim 7 wherein the weighting factor further depends on an estimated wear of each turbine.

13. The method according to claim 7 further comprising,

operating the wind power plant with an active power reference lower than a nominal active power of the wind power plant by curtailing at least some of the wind turbine generators of the plurality of wind turbine generators,

determining a power capability of each of the curtailed wind turbine generators

defining a first group comprising wind turbine generators having a power capability higher than a power capability limit,

defining a second group comprising wind turbine generators having a power capability lower than a power capability limit, and

equalizing curtailment of the curtailed wind turbines generators by decreasing the active power set point for the wind turbines generators in the first group and increasing the active power set point for the wind turbines generators in the second group.

14. The method according to claim 13 , wherein determining the power capability of each of the curtailed wind turbine generators comprises:

calculating a positive power capability as the difference between nominal power and production power; and

calculating a negative power capability as the difference between minimum power and production power.

15. The method according to claim 13 , wherein each wind turbine generator is curtailed based on a set fraction of the available active power of the respective wind turbine generator.