Method for damping drive train oscillations in a wind turbine generator
The present invention relates a wind turbine generator with an electrical generator, a dump load unit, for dissipating power, a wind turbine power controller and a damping controller both arranged to control wind turbine components based on a damping reference signal, the damping reference signal is a combined signal, and comprises a first reference signal and a second reference signal, the second reference signal is an oscillating part, the wind turbine power controller is controlling the power from the electrical generator according to the first reference signal and the damping controller is controlling the dump load unit to dissipate power according to the second reference signal. The invention also relates to a method for damping oscillations with wind turbine generators.
1. A wind turbine generator comprising:
an electrical generator;
a dump load unit configured to dissipate at least a portion of power generated by the electrical generator; and
a wind turbine power controller configured to:
receive a damping reference signal,
derive a first reference signal and a second reference signal from the damping reference signal,
control, based on the first reference signal, power generated by the electrical generator, and
communicate the second reference signal to a damping controller configured to operate the dump load unit based on the second reference signal.
2. A wind turbine generator according to claim 1 , wherein the first reference signal is an envelope curve of the damping reference signal.
3. A wind turbine generator according to claim 2 , wherein the first reference signal is decreasing and starting from a positive value, and wherein the wind turbine power controller is further configured to control the electrical generator based on a positive power reference.
4. A wind turbine generator according to claim 1 , wherein the first reference signal is a monotonic function.
5. A wind turbine generator according to claim 2 , wherein the first reference signal is increasing and starting from a negative value.
6. A wind turbine generator according to claim 5 , wherein the first reference signal is negative, and the wind turbine power controller sends a reference signal equaling zero to the electrical generator.
7. A wind turbine generator according to claim 1 , wherein the first reference signal is substantially zero and wherein the dump load unit dissipates a negative section of the second reference signal.
8. A wind power plant comprising a power plant controller and at least one wind turbine generator according to claim 1 , wherein the power plant controller is configured to:
calculate the first reference signal and the second reference signal,
communicate the first reference signal to the wind turbine power controller of the at least one wind turbine generator, and
communicate the second reference signal to the damping controller of the at least one wind turbine generator.
9. A wind turbine generator according to claim 1 , wherein the dump load unit comprises a storage device for storing energy.
10. A wind turbine generator according to claim 1 , wherein the first reference signal is a non-oscillating signal and the second reference signal is an oscillating signal.
11. A method for damping electrical grid oscillations using a wind turbine generator comprising an electrical generator, a dump load unit configured to dissipate at least a portion of power generated by the electrical generator, a wind turbine power controller, and a damping controller, wherein the method comprises:
receiving a damping reference signal;
determining, based on the damping reference signal, a first reference signal and communicating the first reference signal to the wind turbine power controller for controlling power generation of the electrical generator; and
determining, based on the damping reference signal, a second reference signal and communicating the second reference signal to the damping controller for controlling the dump load unit.
12. A method according to claim 11 , wherein the first reference signal is an envelope curve of the damping reference signal.
13. A method according to claim 12 , wherein the first reference signal is increasing and starting from a negative value.
14. A method according to claim 12 , wherein the first reference signal is decreasing and starting from a positive value, and wherein the wind turbine power controller further configured to control the electrical generator based on a positive power reference.
15. A method according to claim 11 , wherein the first reference signal is a monotonic function.
16. A method according to claim 11 , wherein the first reference signal is substantially zero and wherein the damping controller is controlling the dump load unit to dissipates the negative sections of the second reference signal.
17. A method according to claim 11 , wherein the dump load unit comprises a storage device for storing energy.
18. A method according to claim 11 , wherein the first reference signal is a non-oscillating signal and the second reference signal is an oscillating signal.
19. A wind power plant comprising:
one or more wind turbine generators each comprising:
an electrical generator,
a wind turbine power controller configured to control power generated by the electrical generator based on a first reference signal, and
a damping controller configured to operate a dump load unit based on a second reference signal; and
a power plant controller configured to:
determine a damping reference signal,
calculate the first reference signal based on the damping reference signal,
calculate the second reference signal based on the damping reference signal,
communicate the first reference signal to the wind turbine power controllers of the one or more wind turbine generators, and
communicate the second reference signal to the damping controllers of the one or more wind turbine generators.