초록 ▼

A system for controlling a grid connected power generating system is provided. The system includes a wind turbine, a converter, a first controller and a second controller. The wind turbine supplies electrical power to a power grid and the converter couples the wind turbine to the power grid. The fir

A system for controlling a grid connected power generating system is provided. The system includes a wind turbine, a converter, a first controller and a second controller. The wind turbine supplies electrical power to a power grid and the converter couples the wind turbine to the power grid. The first controller calculates voltage commands to emulate a phasor back electromotive force behind an inductance. The controller further generates converter switching commands from the voltage commands. The voltage commands include a voltage magnitude reference and an internal frequency reference calculated from a power imbalance between an active power reference and the electrical power. The second controller is used to limit a converter current.

대표청구항 ▼

The invention claimed is: 1. A power generating system comprising a wind turbine; a converter configured to couple the wind turbine to a power grid; a first controller configured for calculating voltage commands to emulate a phasor back electromotive force, the controller further configured for usi

The invention claimed is: 1. A power generating system comprising a wind turbine; a converter configured to couple the wind turbine to a power grid; a first controller configured for calculating voltage commands to emulate a phasor back electromotive force, the controller further configured for using the voltage commands for generating converter switching commands, wherein the voltage commands include a voltage magnitude reference, an internal frequency reference calculated from an imbalance between an active power reference and an actual electrical power; and a second controller configured to limit a converter current. 2. The system of claim 1, wherein the wind turbine comprises a squirrel cage induction generator. 3. The system of claim 1, wherein the wind turbine comprises a doubly-fed asynchronous generator. 4. The system of claim 1, wherein the internal frequency reference is different than a power grid frequency. 5. The system of claim 1, wherein the active power reference is generated by a turbine controller. 6. The system of claim 1, wherein the voltage magnitude reference is generated from a reactive power controller. 7. The system of claim 1, wherein second controller comprises an instantaneous current controller, a phasor current limit controller, or a combination thereof. 8. The system of claim 7, wherein the instantaneous current limit controller is configured to block switching signals to switching devices of the converter when the current exceeds a threshold value. 9. The system of claim 7, wherein the phasor current limit controller is configured to limit a phasor current by adjusting a voltage drop across a converter impedance. 10. The system of claim 1, wherein the voltage commands further include a phase angle command. 11. The system of claim 10, wherein the phase angle command is calculated from an integration of the internal frequency command. 12. A solar power generating system comprising a photovoltaic cell; a converter configured to couple the photovoltaic cell to a power grid; a first controller configured for calculating voltage commands to emulate a phasor back electromotive force, the controller further configured for using the voltage commands for generating converter switching commands, wherein the voltage commands include a voltage magnitude reference, an internal frequency reference calculated from an imbalance between an active power reference and an actual electrical power; and a second controller configured to limit a converter current. 13. The solar power generating system of claim 12, wherein the converter comprises a DC to DC converter, DC to AC converter, or a combination thereof. 14. The system of claim 12, wherein the first controller is configured for calculating a phase angle reference by integrating the internal frequency reference. 15. The system of claim 12, wherein the current limit controller comprises an instantaneous current controller, a phasor current limit controller, or a combination thereof. 16. A method of supplying electrical power to a power grid comprising: generating the electrical power from an electrical source; controlling the electrical source to emulate a phasor back electromotive force; and limiting a converter current magnitude; wherein controlling the electrical source comprises calculating voltage commands and using the voltage commands for generating converter switching commands, wherein the voltage commands include a voltage magnitude reference, an internal frequency reference calculated from an imbalance between a active power reference and the electrical power. 17. The method of claim 16, wherein controlling the electrical source comprises calculating a phase angle reference. 18. The method of claim 17, wherein calculating the phase angle reference comprises integrating the internal frequency reference. 19. The method of claim 16, wherein limiting the converter current magnitude comprises adjusting a voltage drop across a converter impedance. 20. The method of claim 16, wherein limiting the converter current magnitude comprises blocking switching signals to switching devices of the converter when the current exceeds a threshold value.