# US 11,028,827 B2 · Operating wind turbine above rating during low erosion conditions > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,028,827 B2 - Document ID: US11028827B2 - Status: Granted - Kind: B2 - Application number: 16/461,591 - Filed: 2017-11-17 - Published: 2019-12-05 - Granted: 2021-06-08 - Earliest claimed: 2016-11-18 - Assignees: MHI Vestas Offshore Wind A/S - Applicants: Mhi Vestas Offshore Wind A/S - Inventors: Hideyasu Fujioka; Alex Pericleous - Web page: https://patentgrep.com/patent/US11028827B2 ## CPC - F03D 7/0224: {Adjusting blade pitch} - F03D 7/0264: {for stopping; controlling in emergency situations (orientating out of wind F03D7/0208)} - F03D 7/0276: {controlling rotor speed, e.g. variable speed} - F03D 7/042: {by means of an electrical or electronic controller} - F03D 7/043: {characterised by the type of control logic} - F03D 17/00: Monitoring or testing of wind motors, e.g. diagnostics (testing during commissioning of wind motors F03D13/30) - F03D 1/00: Wind motors with rotation axis substantially parallel to the air flow entering the rotor (controlling thereof F03D7/02) - F05B 2240/221: with horizontal axis - F05B 2260/74: by turning around an axis perpendicular the rotor centre line - F05B 2260/83: Testing, e.g. methods, components or tools therefor - F05B 2270/101: to control rotational speed (n) - F05B 2270/30: Control parameters, e.g. input parameters - F05B 2270/323: Air humidity - F05B 2270/804: Optical devices - Y02E 10/72: Wind turbines with rotation axis in wind direction - F03D: WIND MOTORS - 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 There is presented a method (320) for controlling a wind turbine (100), wherein said wind turbine comprises a wind turbine rotor (102) with one or more blades (103), wherein the wind turbine has a rated angular rotation speed (214) of the wind turbine rotor, said method comprising obtaining (322) information (323) on ambient conditions, determining, based on said information, if an erosion criterion is fulfilled, controlling (328) the wind turbine according to an extended mode if the erosion criterion is fulfilled, wherein in the extended mode an angular rotation speed of the wind turbine rotor is allowed to exceed the rated angular rotation speed (214). ## Claims ### Claim 1 A method for controlling a wind turbine comprising a wind turbine rotor with one or more blades, wherein the wind turbine has a rated angular rotation speed of the wind turbine rotor, wherein the method comprises: obtaining information on ambient conditions comprising information on rain drops impinging on the one or more blades or information on rain drops being likely to impinge on the one or more blades, determining that an erosion criterion is fulfilled when a physical characteristic of said rain drops satisfies a predetermined threshold, and controlling the wind turbine according to an extended mode upon determining the erosion criterion is fulfilled, wherein in the extended mode, an angular rotation speed of the wind turbine rotor is allowed to exceed the rated angular rotation speed. ### Claim 2 (depends on 1) The method according to claim 1, wherein the physical characteristic is an average drop size of said rain drops. ### Claim 3 (depends on 1) The method according to claim 1, wherein the information on ambient conditions enables estimating an estimated erosion rate, and wherein the method further comprises: estimating, based on said information, the estimated erosion rate, determining that the erosion criterion is fulfilled if the estimated erosion rate is below a predetermined erosion rate threshold. ### Claim 4 (depends on 1) The method according to claim 1, wherein an amount of power produced at an angular rotation speed above the rated angular rotation speed is higher than an amount of power produced at the rated angular rotation speed. ### Claim 5 (depends on 3) The method according to claim 3, wherein in the extended mode the angular rotation speed of the wind turbine rotor is limited below an angular rotation speed threshold, wherein the angular rotation speed threshold is larger than the rated angular rotation speed of the wind turbine. ### Claim 6 (depends on 5) The method according to claim 5, wherein the angular rotation speed threshold is: inversely proportional to the estimated erosion rate, or set so as to maintain a constant erosion rate, or set according to a pre-calculated lookup table relating estimated erosion rate and maximum tip speed, or set according to a maximum corresponding structural load, or set according to a noise level. ### Claim 7 (depends on 5) The method according to claim 5, wherein said angular rotation speed threshold is more than 102% with respect to the rated angular rotation speed. ### Claim 8 (depends on 1) The method according to claim 1, wherein the information on ambient conditions further comprises information on one or more of: solid particles in air surrounding the wind turbine, liquid particles in air surrounding the wind turbine, or humidity. ### Claim 9 (depends on 1) The method according to claim 1, wherein the information on ambient conditions further comprises information on hailstones impinging on the one or more blades or being likely to impinge on the one or more blades. ### Claim 10 (depends on 1) The method according to claim 1, wherein obtaining said information comprises: receiving data from: a precipitation sensor selected from: an optical rain gauge, and an acoustic rain gauge; or a humidity sensor configured to perform at least one of: receive a weather report, receive a weather forecast, and receive data or a forecast from another wind turbine, a substation, or a remote control center. ### Claim 11 (depends on 1) The method according to claim 1, wherein the method further comprises: controlling the angular rotation speed according to the extended mode, subsequently obtaining subsequent information on ambient conditions, which information enables estimating a subsequently estimated erosion rate, subsequently estimating, based on said subsequent information, the subsequently estimated erosion rate, and discontinuing controlling the wind turbine according to the extended mode if the subsequently estimated erosion rate is above a predetermined erosion rate level. ### Claim 12 (depends on 1) The method according to claim 1, wherein said wind turbine further comprises: a pitch control system for controlling a pitch angle of the one or more blades, and wherein the method further comprises: controlling the angular rotation speed by controlling the pitch angle of the one or more blades with the pitch control system. ### Claim 13 A computer program product comprising a non-transitory computer-readable medium having instructions stored thereon which, when executed by one or more processors, cause a control system for a wind turbine to perform an operation, wherein the wind turbine comprises a wind turbine rotor with one or more blades, wherein the wind turbine has a rated angular rotation speed of the wind turbine rotor; the operation, comprising: obtaining information on ambient conditions comprising information on rain drops impinging on the one or more blades or information on rain drops being likely to impinge on the one or more blades, determining that an erosion criterion is fulfilled when a physical characteristic of said rain drops satisfies a predetermined threshold, and controlling the wind turbine according to an extended mode upon determining the erosion criterion is fulfilled, wherein in the extended mode, an angular rotation speed of the wind turbine rotor is allowed to exceed the rated angular rotation speed. ### Claim 14 (depends on 13) The computer program product according to claim 13, wherein the physical characteristic is an average drop size of the rain drops. ### Claim 15 (depends on 13) The computer program product according to claim 13, wherein the information on ambient conditions enables estimating an estimated erosion rate, and wherein the operation further comprises: estimating, based on the obtained information, the estimated erosion rate, determining that the erosion criterion is fulfilled if the estimated erosion rate is below a predetermined erosion rate threshold. ### Claim 16 (depends on 13) The computer program product according to claim 13, wherein an amount of power produced at an angular rotation speed above the rated angular rotation speed is higher than an amount of power produced at the rated angular rotation speed. ### Claim 17 (depends on 13) The computer program product according to claim 13, wherein in the extended mode the angular rotation speed of the wind turbine rotor is limited below an angular rotation speed threshold, wherein the angular rotation speed threshold is larger than the rated angular rotation speed of the wind turbine. ### Claim 18 A wind turbine, comprising: a tower; a nacelle disposed on the tower; a rotor extending from the nacelle, wherein the wind turbine has a rated angular rotation speed of the rotor; a plurality of blades disposed on one end of the rotor; and a control system configured to perform an operation, the operation comprising: obtaining information on ambient conditions comprising information on rain drops impinging on one of the plurality of blades or information on rain drops being likely to impinge on the one of the plurality of blades, determining that an erosion criterion is fulfilled when a physical characteristic of said rain drops satisfies a predetermined threshold, and controlling the wind turbine according to an extended mode upon determining the erosion criterion is fulfilled, wherein in the extended mode, an angular rotation speed of the rotor is allowed to exceed the rated angular rotation speed. ### Claim 19 (depends on 18) The wind turbine of claim 18, wherein obtaining the information comprises receiving information from: a precipitation sensor selected from: an optical rain gauge, and an acoustic rain gauge; or a humidity sensor configured to perform at least one of: receive a weather report, receive a weather forecast, and receive data or a forecast from another wind turbine, a substation, or a remote control center. ### Claim 20 (depends on 18) The wind turbine according to claim 18, wherein the physical characteristic is an average drop size of the rain drops.