# US 11,078,887 B2 · Method for operating a wind farm

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- Number: US 11,078,887 B2
- Document ID: US11078887B2
- Status: Granted
- Kind: B2
- Application number: 16/896,935
- Filed: 2020-06-09
- Published: 2020-12-17
- Granted: 2021-08-03
- Earliest claimed: 2019-06-17
- Assignees: Nordex Energy GmbH
- Applicants: Nordex Energy SE & Co. KG
- Inventors: Georg Grosseholz
- Web page: https://patentgrep.com/patent/US11078887B2

## CPC

- F03D 7/048: {controlling wind farms}
- F03D 7/0284: {in relation to the state of the electric grid}
- H02J 3/381: {Dispersed generators}
- F05B 2270/1033: Power (if explicitly mentioned)
- F05B 2270/337: Electrical grid status parameters, e.g. voltage, frequency or power demand
- H02J 2101/28: Wind energy
- Y02E 10/72: Wind turbines with rotation axis in wind direction
- Y02E 10/76: Power conversion electric or electronic aspects
- F03D: WIND MOTORS
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- F05B: INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A method for operating a wind farm having a plurality of wind turbines that are able to be driven and/or able to be set in response to a received setpoint value of a power-related electrical variable in order to output a power, wherein the method allots an amount of power to be distributed iteratively over the wind turbines taking into account minimum power limits of the wind turbines.

## Claims

### Claim 1

A method for operating a wind farm having a plurality of wind turbines that are adapted to be controlled in response to a received setpoint value of a power-related electrical variable in order to output a power, the method comprising the steps of:
a) determining an amount of power to be distributed over the wind turbines in dependence upon a setpoint power for the wind farm and on minimum power limits of individual ones of the plurality of wind turbines;
b) generating a first weighted distribution that assigns a respective portion of the amount of power to be distributed to the individual ones of the plurality of wind turbines;
c) defining a setpoint value for each of the wind turbines that are able to output as much power as was assigned to them by the first weighted distribution or less, wherein each of the setpoint values is defined on a basis of a currently available power of a corresponding wind turbine, wherein each of the setpoint values are defined such that the corresponding wind turbines are each controlled to output the currently available power but at least to output the minimum power of the corresponding wind turbine;
d) determining a remaining amount of power still to be distributed;
e) generating a further weighted distribution that assigns a respective portion of the remaining amount of power to remaining ones of the plurality of wind turbines that, on the basis of a currently available power of corresponding ones of the plurality of wind turbines, are able to output more power than was assigned to them by a directly preceding previous weighted distribution;
f) defining further setpoint values for the remaining ones of the plurality of wind turbines that, on a basis of a currently available power of corresponding ones of the plurality of wind turbines, are able to output as much power as was assigned to them by the further weighted distribution or less, wherein the further setpoint values are defined such that corresponding wind turbines are each controlled to output the currently available power of corresponding ones of the plurality of wind turbines;
g) determining whether a stop condition for the method is met, wherein steps d) to f) are repeated until the stop condition for the method has been met; and,
h) providing the defined setpoint values to the corresponding ones of the plurality of wind turbines of the wind farm.

### Claim 2 (depends on 1)

The method of claim 1, wherein the amount of power to be distributed over the wind turbines is determined in step a) as a deviation (SPp−Σk CMPLk) from the setpoint power for the wind farm (SPp) and the minimum power limits (CMPLj) of all of the wind turbines (Σk CMPLk).

### Claim 3 (depends on 1)

The method of claim 1, wherein the first weighted distribution is generated in step b) by determining intermediate values (V2SPj) as a sum of respective minimum power limits (CMPLj) of the corresponding wind turbine and a deviation (SPp−Σk CMPLk) multiplied by a weighting factor (gj).

### Claim 4 (depends on 3)

The method of claim 3, wherein, in step c), for the wind turbines for which the previously determined intermediate value (V2SPj*) is greater than or equal to the currently available power (Paj*) of the corresponding wind turbines, the currently available power (PAj*) at each of the corresponding wind turbines but at least the respective minimum power limit (CMPLj*) of the corresponding wind turbines is defined as the setpoint value.

### Claim 5 (depends on 3)

The method of claim 3, wherein, in step d), the remaining amount of power still to be distributed is determined as a further deviation (Σk*(V2SPk*−PAk*)) calculated as the sum of the differences between respective intermediate values (V2SPj*) and respective currently available power (PAj*) of the wind turbines for which the previously determined intermediate value (V2SPj*) is greater than or equal to the currently available power (PAj*).

### Claim 6 (depends on 1)

The method of claim 1, wherein a remaining amount of power that remains and is still to be distributed is determined as a deviation (Σk*(CMPLk*−PAk*)) calculated as the sum of the differences between minimum power limits (CMPLj*) and a respective currently available power (PAj*) of the wind turbines whose currently available power (PAj*) is less than a minimum power (PAj*<CMPLj*) provided for the corresponding wind turbine.

### Claim 7 (depends on 6)

The method of claim 6, wherein the amount of power to be distributed is corrected depending on the remaining amount of power.

### Claim 8 (depends on 3)

The method of claim 3, wherein, in step e), the further weighted distribution is created by determining further intermediate values (V3SPj#) as the sum of the respective previous intermediate values (V2SPj#) and the further deviation (Σk*(V2SPk*−PAk*)) multiplied by a further weighting factor (fj).

### Claim 9 (depends on 8)

The method of claim 8, wherein, in step f), for those of the remaining wind turbines for which the previously determined further intermediate value (V3SPj#) is greater than or equal to the currently available power (PAj#) of the corresponding wind turbine, the power (PAj#) currently available at each of these wind turbines is defined as the setpoint value.

### Claim 10 (depends on 1)

The method of claim 1, wherein the stop condition for the method is met when at least one of the remaining amount of power is equal to or less than a specified threshold value and the method has run through a predetermined number of iterations.

### Claim 11 (depends on 1)

The method of claim 1, wherein the first weighted distribution and the further weighted distribution have the same weighting and/or wherein a first weighting factor (gj) and a further weighting factor (fj) are the same.

### Claim 12 (depends on 1)

The method of claim 1, wherein the weighting of the first weighted distribution and/or of the further weighted distribution depends on the currently available power of the corresponding wind turbine, wherein wind turbines having a greater currently available power are weighted to a greater extent than wind turbines having a lower currently available power.

### Claim 13 (depends on 1)

The method of claim 1, wherein the weighting of the first weighted distribution and/or of the further weighted distribution depends on the deviation between a nominal power and the minimum power of the corresponding wind turbine, wherein wind turbines having a smaller deviation are weighted to a greater extent than wind turbines having a larger deviation.

### Claim 14 (depends on 1)

The method of claim 1, wherein the weighting of at least one of the first weighted distribution and the further weighted distribution depends on the nominal power of the corresponding wind turbine, wherein wind turbines having a greater nominal power are weighted to a greater extent than wind turbines having a lower nominal power.

### Claim 15 (depends on 6)

The method of claim 6, wherein the amount of power to be distributed is corrected by a controller depending on the remaining amount of power.

### Claim 16 (depends on 10)

The method of claim 10, wherein the predetermined number of iterations depends on the wind conditions.

### Claim 17

A wind farm comprising:
a plurality of wind turbines;
at least one control unit configured to:
a) determine an amount of power to be distributed over said plurality of wind turbines in dependence upon a setpoint power for the wind farm and on minimum power limits of individual ones of said plurality of wind turbines;
b) generate a first weighted distribution that assigns a respective portion of the amount of power to be distributed to the individual ones of said plurality of wind turbines;
c) define setpoint values for a first subset of said plurality of wind turbines that are able to output as much power as was assigned to them by the first weighted distribution or less, wherein each of the set point values is defined on a basis of a currently available power of a corresponding wind turbine, wherein each of the setpoint values are defined such that said subset of said plurality of wind turbines are each controlled to output the currently available power but at least to output the minimum power of the corresponding wind turbine;
d) determine a remaining amount of power still to be distributed;
e) generate a further weighted distribution that assigns a respective portion of the remaining amount of power to a second subset of said plurality of wind turbines that are able to output more power than was assigned to them by a directly preceding previous weighted distribution based on a currently available power of corresponding ones of said second subset;
f) define further setpoint values for remaining ones of said plurality of wind turbines that are able to output as much power as was assigned to them by the further weighted distribution based on a currently available power of each of the remaining ones of said plurality of wind turbines or less, wherein the further setpoint values are defined such that said remaining ones of said plurality of wind turbines are each controlled to output the currently available power of corresponding ones of the remaining ones of said plurality of wind turbines;
g) determining whether a stop condition for the method has been met, wherein steps d) to f) are repeated until the stop condition is met; and,
h) provide the defined setpoint values to the corresponding ones of said plurality of wind turbines of the wind farm;
wherein said at least one control unit is a control unit superordinate to said plurality of wind turbines.