Auxiliary power system for turbine-based energy generation system

1. A power system for a turbine-based energy generation system including an electric generator and an auxiliary load, comprising:

a main converter;

an auxiliary converter;

a switch module interposed between the electric generator and the main and auxiliary converters; and

a controller operable to close the switch module so that the electric generator is coupled to the main and auxiliary converters when a power generation criterion exceeds a first threshold and open the switch module so that the electric generator is decoupled from the main and auxiliary converters when the power generation criterion is below a second threshold,

wherein the main converter is operable to deliver power generated by the electric generator to a power collection system external to the turbine-based energy generation system when the main converter is coupled to the generator and deliver power provided from the power collection system to the auxiliary converter when the main converter is decoupled from the generator,

wherein the auxiliary converter is operable to deliver power generated by the electric generator to the auxiliary load when the auxiliary converter is coupled to the generator and deliver the power provided by the main converter from the power collection system to the auxiliary load when the auxiliary converter is decoupled from the generator.

2. The power system of claim 1 , further comprising an energy storage device coupled to the auxiliary converter, and wherein the auxiliary converter is operable to deliver power provided by the energy storage device to the auxiliary load when the auxiliary converter is decoupled from the generator.

3. The power system of claim 2 , further comprising a bidirectional converter coupling the auxiliary converter to the energy storage device.

4. The power system of claim 3 , wherein the auxiliary converter comprises a rectifier operable to convert AC electrical energy from the electric generator or the main converter to DC electrical energy and an inverter operable to convert the DC electrical energy back to AC electrical energy for the auxiliary load, and wherein the bidirectional converter is connected between the rectifier and the inverter at one side and to the energy storage device at another side.

5. The power system of claim 1 , wherein the main converter is a bidirectional converter operable to convert AC electrical energy from the electric generator to DC electrical energy delivered to the power collection system when the main converter is coupled to the generator and convert DC electrical energy from the power collection system to AC electrical energy delivered to the auxiliary converter when the main converter is decoupled from the generator.

6. The power system of claim 5 , wherein the bidirectional converter is a modular multilevel converter.

7. The power system of claim 1 , wherein the auxiliary load is at least partly a DC load and the auxiliary converter is operable to convert AC electrical energy at a first side of the auxiliary converter to DC electrical energy at a second side of the auxiliary converter coupled to the at least partly DC load.

8. The power system of claim 7 , further comprising a DC bus connecting the second side of the auxiliary converter to the at least partly DC load.

9. The power system of claim 1 , further comprising a three-winding transformer connecting the auxiliary converter, the switch module and the main converter.

10. The power system of claim 1 , further comprising:

a first two-winding transformer connecting the switch module to the main converter; and

a second two-winding transformer connecting the auxiliary converter to the first two-winding transformer and the main converter.

11. The power system of claim 1 , further comprising:

a first two-winding transformer connecting the switch module to the main converter; and

a second two-winding transformer connecting the auxiliary converter to the first two-winding transformer and the switch module.

12. The power system of claim 1 , wherein the power generation criterion comprises at least one of voltage of the electric generator, current of the electric generator and wind speed.

13. The power system of claim 12 , wherein the controller is operable to open the switch module when the wind speed is below a cut-in speed of a rotor assembly connected to the electric generator.

14. The power system of claim 1 , wherein the controller is operable to switch the switch module under zero-current switching conditions.

15. A method of providing power to an auxiliary load of a turbine-based energy generation system also including an electric generator, a main converter and an auxiliary converter, and a switch module interposed between the electric generator and the main and auxiliary converters, the method comprising:

delivering power generated by the electric generator to a power collection system external to the turbine-based energy generation system via the main converter when the main converter is coupled to the generator;

delivering power generated by the electric generator to the auxiliary load via the auxiliary converter when the auxiliary converter is coupled to the generator;

delivering power provided from the power collection system to the auxiliary converter via the main converter when the main converter is decoupled from the generator;

delivering the power provided by the main converter from the power collection system to the auxiliary load via the auxiliary converter when the auxiliary converter is decoupled from the generator;

closing the switch module so that the electric generator is coupled to the main and auxiliary converters when a power generation criterion exceeds a first threshold; and

opening the switch module so that the electric generator is decoupled from the main and auxiliary converters when the power generation criterion is below a second threshold.

16. The method of claim 15 , wherein the turbine-based energy generation system further comprises an energy storage device coupled to the auxiliary converter, the method further comprising:

delivering power provided by the energy storage device to the auxiliary load via the auxiliary converter and a bidirectional converter coupling the auxiliary converter to the energy storage device when the auxiliary converter is decoupled from the generator.

17. The method of claim 15 , wherein the main converter is a bidirectional converter, the method further comprising:

converting AC electrical energy from the electric generator to DC electrical energy by the bidirectional converter for delivery to the power collection system when the main converter is coupled to the generator; and

converting DC electrical energy from the power collection system to AC electrical energy by the bidirectional converter for delivery to the auxiliary converter when the main converter is decoupled from the generator.

18. The method of claim 15 , wherein the auxiliary load is at least partly a DC load, the method further comprising:

converting AC electrical energy at a first side of the auxiliary converter to DC electrical energy at a second side of the auxiliary converter coupled to the at least partly DC load; and

connecting the second side of the auxiliary converter to the at least partly DC load via a DC bus.

19. The method of claim 15 , wherein the turbine-based energy generation system further comprises a rotor assembly connected to the electric generator, the method further comprising:

opening the switch module when the wind speed is below a cut-in speed of the rotor assembly.

20. The method of claim 15 , further comprising:

switching the switch module under zero-current switching conditions.