WIND POWER PLANT HAVING FREQUENCY MEASUREMENT

• US 20160040652A1
• Filed: 03/04/2014
• Published: 02/11/2016
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Siemens Gamesa Renewable Energy Service GmbH (Siemens AG)
• Original Assignee: Senvion GmbH (Senvion SE)
• Inventors: BLUHM, Roman
• Granted Patent: US 10,458,392 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F03D 7/0284 in relation to the state of the electric grid
• CPC Class Codes: F03D 9/255 connected to electrical distribution networks; Arrangements therefor
• CPC Class Codes: F05B 2270/309 Rate of change of parameters
• CPC Class Codes: F05B 2270/337 Electrical grid status parameters, e.g. voltage, frequency or power demand
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy wind motors F03D
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction
• CPC Class Codes: Y02E 10/76 Power conversion electric or electronic aspects

Abstract

A method for controlling a wind turbine which is connected to an electrical grid, detects a grid frequency present in the grid and in the case of which the power output is regulated on the basis of the grid frequency by a controller and, in particular, switches off the power feed into the electrical grid if a limit value of a grid frequency is exceeded, wherein a change in the grid frequency over time is detected, a rate of change is determined and the rate of change is compared with a rate of change limit value and a modified frequency value is used to regulate the power output in the event of the rate of change limit value being exceeded.

Claims

1. A method for controlling a wind turbine which is connected to an electrical grid comprising determining a grid frequency present in the grid and regulating the power output of the wind turbine based on the grid frequency, wherein regulating the power output comprises detecting a change in the grid frequency over time, determining a rate of change of the grid frequency, comparing the rate of change of the grid frequency with a rate of change limit value,. and using a modified frequency value to regulate the power output when the rate of change of the grid frequency exceeds the rate of change limit value.

2. The method for controlling a wind turbine of claim 1, wherein the modified frequency value has a lower rate of change in comparison with the grid frequency and, the modified frequency value is calculated using an increase value or an increase function.

3. The method for controlling a wind turbine of claim 2, wherein at least one of the rate of change limit value and the increase value is selected to be in the range of a maximum rate of change of frequency of the electrical grid.

4. The method for controlling a wind turbine of claim 1, wherein use of the modified frequency value is temporally limited.

5. The method for controlling a wind turbine of claim 1, comprising measuring grid voltage present in the grid, wherein the modified frequency is used when a voltage limit value is exceeded at the same time that the rate of change limited value is exceeded.

6. The method for controlling a wind turbine of claim 1, wherein the frequency is determined from temporal spacing of zero-crossings of grid voltage, both with positive and with negative gradient.

7. The method for controlling a wind turbine of claim 1, wherein the frequency is determined from a voltage profile of all three phases.

13. The method for controlling a wind turbine of claim 1, comprising switching off the power feed into the electrical grid if a limit value of a grid frequency is exceeded.

14. The method for controlling a wind turbine of claim 3, wherein the maximum rate of change of frequency of the electrical grid is in a range from 3 to 15 Hz/s.

15. The method for controlling a wind turbine of claim 4, wherein regulating the power output comprises ceasing to use the modified frequency value and using the determined grid frequency once a predefinable time has elapsed.

8. A wind turbine comprising a generator driven by a wind-powered rotor for outputting electric power, a converter for converting at least some of the power output by the generator, a frequency detection module for detecting a frequency present in a connected electrical grid and outputting the detected frequency, and a controller configured to regulate the power output of the wind turbine on the basis of the detected frequency output by the frequency detection module, wherein the frequency detection module comprises

an increase module for determining a rate of change of the detected frequency over time and comparing the rate of change with a rate of change limit value, and

a limiting module configured to calculate a modified frequency value and output the modified frequency value to the controller when the rate of change of the detected frequency exceeds the rate of change limit value in the increase module.

9. The wind turbine of claim 8, wherein a predefined increase value or a predefined increase function is stored in the limiting module and the modified frequency value is calculated using the increase value or the increase function and, the modified frequency value has a lower rate of change in comparison with the grid frequency.

10. The wind turbine of claim 8, wherein at least one of the rate of change limit value and the increase value is selected to be in the range of a maximum rate of change of frequency of the electrical grid.

11. The wind turbine of claim 8, wherein the frequency detection module comprises a plausibility module configured to overmodulate the output of the modified frequency value such that the detected frequency is output to the controller.

12. The wind turbine of claim 11, wherein the plausibility module performs the overmodulation on the basis of the time which has elapsed since a start of at least one of a frequency increase and exceedance of a voltage limit value.

16. The wind turbine of claim 10, wherein the maximum rate of change of frequency of the electrical grid is in a range from 3 to 15 Hz/s.