Method for starting an energy generation network

Patent metadata

Field	Value
Publication number	US-11070057-B2
Application number	US-201816494214-A
Country	US
Kind code	B2
Filing date	Mar 22, 2018
Priority date	Mar 23, 2017
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

A method for starting a farm grid of a wind farm is provided. The energy generation grid has at least one grid connection point connected to an electrical supply grid and the energy generation grid, in a normal operating mode, exchanges electrical power with the electrical supply grid via the grid connection point. The method includes selecting an establishment mode, different than the normal operating mode, if the electrical supply grid has a voltage drop or the energy generation grid is isolated from the electrical supply grid and operating the energy generation grid in the establishment mode. The establishment mode at least one voltage-influencing wind power installation for providing a wind farm grid voltage and at least one current-influencing wind power installation that synchronizes to the energy generation grid voltage. The wind power installations in total provide an electrical power at the level of an inherent need of the grid.

First claim

The invention claimed is:

1. A method for starting a wind farm grid of a wind farm, wherein the wind farm grid has at least one grid connection point connected to an electrical supply grid, and wherein the wind farm grid, in a normal operating mode, exchanges electrical power with the electrical supply grid via the grid connection point, the method comprising:
selecting an establishment mode, different than the normal operating mode, in response to the electrical supply grid having a voltage drop or the wind farm grid being isolated from the electrical supply grid; and
operating the wind farm grid in the establishment mode, wherein in the establishment mode:
at least one voltage-influencing wind power installation provides a wind farm grid voltage,
at least one current-influencing wind power installation synchronizes to the wind farm grid voltage provided via the at least one voltage-influencing wind power installation, and
the at least one voltage-influencing wind power installation and the at least one current-influencing wind power installation in total provide an electrical power in the wind farm grid,

wherein operation of the at least one voltage-influencing wind power installation is based on at least a first droop and operation of the at least one current-influencing wind power installation is based on at least a second droop, wherein the first droop has a smaller gradient than the second droop, and wherein each droop of the first and second droops describes a respective relationship between:
a voltage of the wind farm grid and a reactive power to be supplied or that has been supplied; or
a frequency of the wind farm grid and a real power to be supplied or has been supplied.

2. The method as claimed in claim 1 , wherein the at least one voltage-influencing wind power installation provides the wind farm grid voltage substantially without power, or supplies a power that is 20% lower than a power supplied by the at least one current-influencing wind power installation.

3. The method as claimed in claim 1 , wherein the at least one voltage-influencing wind power installation operates in a voltage-influencing manner to provide the wind farm grid voltage.

4. The method as claimed in claim 1 , wherein the at least one current-influencing wind power installation operates in a current-influencing manner to provide an electrical power in the wind farm grid.

5. The method as claimed in claim 1 , wherein the operation of the at least one voltage-influencing wind power installation is based on a first reactive power droop describing a relationship between a voltage to be provided by the at least one voltage-influencing wind power installation in the wind farm grid and a reactive power supplied by the at least one voltage-influencing wind power installation,
wherein the operation of the at least one current-influencing wind power installation is based on a second reactive power droop describing a relationship between the voltage of the wind farm grid and a reactive power to be supplied by the current-influencing wind power installation, and
wherein:
the first reactive power droop has a smaller gradient than the second reactive power droop,
the operation of the at least one voltage-influencing wind power installation is based on a first real power droop describing a relationship between a frequency to be provided in the wind farm grid by the at least one voltage-influencing wind power installation and a real power supplied by the at least one voltage-influencing wind power installation,
the operation of the at least one current-influencing wind power installation is based on a second real power droop describing a relationship between a frequency recorded in the wind farm grid and a real power to be supplied by the at least one current-influencing wind power installation, and
the first real power droop has a smaller gradient than the second real power droop.

6. The method as claimed in claim 5 , wherein:
the at least one voltage-influencing wind power installation provides the voltage based on the supplied reactive power according to the first reactive power droop,
the at least one current-influencing wind power installation supplies the reactive power based on the voltage of the wind farm grid according to the second reactive power droop,
the at least one voltage-influencing wind power installation provides the frequency based on the supplied real power according to the first real power droop, and
the at least one current-influencing wind power installation supplies the real power based on the recorded frequency according to the second real power droop.

7. The method as claimed in claim 5 , wherein a gradient or gain of the second droop, second reactive power droop, or second real power droop is at least twice a gradient or gain of the first droop, reactive power droop, or real power droop, respectively.

8. The method as claimed in claim 1 , comprising:
selecting of the establishment mode by changing from the normal operating mode to the establishment mode when the wind farm grid has a voltage drop.

9. The method as claimed in claim 1 , comprising:
operating of the wind farm grid in the establishment mode only when the wind farm grid is de-energized.

10. The method as claimed in claim 1 , wherein the at least one current-influencing wind power installation and a further current-influencing wind power installation are synchronized in a cascaded fashion to provide the electrical power in the wind farm grid.

11. The method as claimed in claim 1 , wherein the electrical power provided by the at least one current-influencing wind power installation in the wind farm grid has at least one reactive power component that covers a reactive power requirement of the wind farm grid.

12. The method as claimed in claim 1 , wherein the electrical power provided by the at least one current-influencing wind power installation in the wind farm grid has at least one reactive power component and one real power component, wherein the reactive power component is at least twice the real power component.

13. The method as claimed in claim 1 , wherein the electrical supply grid has a supply voltage and the wind farm grid voltage is ramped up to the supply voltage to synchronize the wind farm grid to the electrical supply grid.

14. The method as claimed in claim 1 , comprising:
connecting the wind farm grid to the electrical supply grid via a wind farm transformer in response to the wind farm grid having the wind farm grid voltage synchronized to the electrical supply grid or to provide a grid reestablishment voltage at the grid connection point in response to the electrical supply grid having no voltage.

15. The method as claimed in claim 1 , comprising:
ramping down the at least one voltage-influencing wind power installation and the at least one current-influencing wind power installation such that the wind farm grid is de-energized if the electrical supply grid has a voltage drop.

16. The method as claimed in claim 1 , wherein the at least one voltage-influencing wind power installation provides the wind farm grid voltage only when the wind farm grid is de-energized.

17. The method as claimed in claim 1 , wherein the voltage drop is defined in relation to a rated voltage of the electrical supply grid as:
a voltage less than 90 percent of the rated voltage;
a voltage less than 70 percent of the rated voltage;
a voltage less than 30 percent of the rated voltage; and
a voltage less than 10 percent of the rated voltage.

18. The method as claimed in claim 1 ,

Assignees

• Wobben Properties Gmbh

Inventors

• Brombach Johannes
• Mackensen Ingo
• Busker Kai

Classifications

• H02J2101/28

  Wind energy · CPC title

• Y02E10/76

  Power conversion electric or electronic aspects · CPC title

• Y02E10/72

  Wind turbines with rotation axis in wind direction · CPC title

• H02J3/40

  Synchronisation of generators for connection to a network or to another generator · CPC title

• H02J3/381 Primary

  Dispersed generators · CPC title