Method and arrangement for operating a wind turbine converter
AssigneeSiemens Aktiengesellschaft
InventorsBjörn Andresen, Bo Yin
Life of this patent
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Abstract
A method of operating a converter of a wind turbine for providing electric energy to a utility grid includes determining a grid voltage. If the grid voltage is between a nominal voltage and a first voltage threshold, i.e. higher than the nominal voltage, a normal procedure for lowering the grid voltage is performed. If the grid voltage is above the first voltage threshold, another procedure for keeping the wind turbine connected is performed, wherein the other procedure is different from the normal procedure. Further a corresponding arrangement is described.
Claims14
Method of operating a converter of a wind turbine for providing electric energy to a utility grid, the method comprising:
- determining a grid voltage;
- performing a first procedure including lowering the grid voltage if the grid voltage is between a nominal voltage and a first voltage threshold, the first voltage threshold being greater than the nominal voltage;
- performing a second procedure if the grid voltage is above the first voltage threshold, wherein the second procedure includes keeping a DC voltage of a converter in a specific range,
- wherein the first and second procedure are different, wherein the second procedure comprises, after enabling a chopper, disabling a pulse width modulation, wherein disabling the pulse width modulation comprises:
- switching a second controllable switch of a grid side converter portion to a non-conducting state,
- dissipating electric energy by current flow through a diode,
- wherein the second controllable switch and the diode are connected in parallel between two DC-nodes of a DC-link of the converter,
- wherein the second controllable switch is provided with pulse width modulation signals for controlling a conductance state of the second controllable switch to change with a higher frequency than the grid frequency, if the grid voltage deviates from the nominal voltage by less than a predefined percentage.
Method of operating a converter of a wind turbine for providing electric energy to a utility grid, the method comprising:
- determining a grid voltage;
- performing a first procedure including lowering the grid voltage if the grid voltage is between a nominal voltage and a first voltage threshold, the first voltage threshold being greater than the nominal voltage;
- performing a second procedure if the grid voltage is above the first voltage threshold, wherein the second procedure includes keeping a DC voltage of a converter in a specific range, wherein the first and second procedure are different;
- performing a third procedure if the grid voltage is above the first voltage threshold and below a second voltage threshold;
- and
- performing a fourth procedure if the grid voltage is above the second voltage threshold, wherein the third procedure comprises, if the grid voltage is above the first voltage threshold and below the second voltage threshold, for at least a first time interval, pitching out rotor blades, wherein pitching out rotor blades comprises adjusting a pitch angle of at least one rotor blade of the wind turbine to capture less energy from wind resource.
Dependencies are inferred from the claim text.