Patents by Inventor Ramakrishnan Krishna

Ramakrishnan Krishna has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 9822764
    Abstract: An automatic adjustment system for a variable-speed wind turbine is provided, having a power vector generator for generating a power vector (Pvec) of wind turbine output power; a mapping unit for establishing relationships (?vec, ?vec) between wind turbine output power and rotational speed and pitch angle on the basis of the power vector (Pvec) and an operational trajectory of the wind turbine; a wind speed estimator for estimating a wind speed (vest); an available power calculator for calculating the available power (Pest) of the wind turbine on the basis of the estimated wind speed (vest) and the established relationships (?vec, ?vec). A method of performing automatic analysis of a wind turbine configuration, a computer program product for carrying out the steps of such a method, and a wind turbine having such an automatic adjustment system are also provided.
    Type: Grant
    Filed: October 5, 2014
    Date of Patent: November 21, 2017
    Assignee: SIEMENS AKTIENGESELLSCHAFT
    Inventors: Thomas Esbensen, Ramakrishnan Krishna, Frank Scheurich, Michael Stoettrup
  • Patent number: 9611834
    Abstract: A method of controlling a wind turbine having a rotor to which at least one rotor blade is connected, is provided herein. The method includes operating the rotor according to a first rotational speed reference; and operating the rotor according to a second rotational speed reference above the first rotational speed reference, if a fluctuation of an actual rotational speed of the rotor decreases below a fluctuation threshold and/or if a blade pitch angle of the rotor blade increases above a blade pitch angle threshold. The method may further include wherein the rotor is operated according to the first rotational speed reference, if the fluctuation of an actual rotational speed of the rotor increases above another fluctuation threshold which is above the fluctuation threshold and/or if the blade pitch angle of the rotor blade decreases below another blade pitch angle threshold which is below the blade pitch angle threshold.
    Type: Grant
    Filed: March 21, 2013
    Date of Patent: April 4, 2017
    Assignee: Siemens Aktiengesellschaft
    Inventors: Thomas Esbensen, Ramakrishnan Krishna
  • Patent number: 9249779
    Abstract: A method for controlling a wind turbine with a rotor and at least one rotor blade, and a control unit are disclosed. The method is characterized in adjusting a pitch angle of the rotor blade and determining the limit of an input value based on the adjusted pitch angle, wherein the input value includes information about the turbine rotational speed.
    Type: Grant
    Filed: December 18, 2012
    Date of Patent: February 2, 2016
    Assignee: SIEMENS AKTIENGESELLSCHAFT
    Inventors: Martin Huus Bjerge, Per Egedal, Gustav Hoegh, Ramakrishnan Krishna, Hans Laurberg
  • Patent number: 9189755
    Abstract: A method of determining an estimated wind speed of a wind driving a wind turbine includes measuring a current power generated by the wind turbine, measuring a current rotor speed of a rotor of the wind turbine, and measuring a current blade pitch angle of a rotor blade of the rotor. Moreover, the method includes determining the estimated wind speed based on the current power, the current rotor speed and the current blade pitch angle.
    Type: Grant
    Filed: September 22, 2009
    Date of Patent: November 17, 2015
    Assignee: SIEMENS AKTIENGESELLSCHAFT
    Inventor: Ramakrishnan Krishna
  • Publication number: 20150226183
    Abstract: A method of controlling a wind turbine having a rotor to which at least one rotor blade is connected, is provided herein. The method includes operating the rotor according to a first rotational speed reference; and operating the rotor according to a second rotational speed reference above the first rotational speed reference, if a fluctuation of an actual rotational speed of the rotor decreases below a fluctuation threshold and/or if a blade pitch angle of the rotor blade increases above a blade pitch angle threshold. The method may further include wherein the rotor is operated according to the first rotational speed reference, if the fluctuation of an actual rotational speed of the rotor increases above another fluctuation threshold which is above the fluctuation threshold and/or if the blade pitch angle of the rotor blade decreases below another blade pitch angle threshold which is below the blade pitch angle threshold.
    Type: Application
    Filed: March 21, 2013
    Publication date: August 13, 2015
    Applicant: Siemens Aktiengesellschaft
    Inventors: Thomas Esbensen, Ramakrishnan Krishna
  • Publication number: 20150097373
    Abstract: An automatic adjustment system for a variable-speed wind turbine is provided, having a power vector generator for generating a power vector (Pvec) of wind turbine output power; a mapping unit for establishing relationships (?vec, ?vec) between wind turbine output power and rotational speed and pitch angle on the basis of the power vector (Pvec) and an operational trajectory of the wind turbine; a wind speed estimator for estimating a wind speed (vest); an available power calculator for calculating the available power (Pest) of the wind turbine on the basis of the estimated wind speed (vest) and the established relationships (?vec, ?vec). A method of performing automatic analysis of a wind turbine configuration, a computer program product for carrying out the steps of such a method, and a wind turbine having such an automatic adjustment system are also provided.
    Type: Application
    Filed: October 5, 2014
    Publication date: April 9, 2015
    Applicant: SIEMENS AKTIENGESELLSCHAFT
    Inventors: Thomas Esbensen, Ramakrishnan Krishna, Frank Scheurich, Michael Stoettrup
  • Patent number: 8897922
    Abstract: A method for controlling the operation of a wind farm with a plurality of wind turbines is disclosed A setpoint vector is defined, wherein each component of the setpoint vector represents an individual power setpoint of one of the plurality of wind turbines. A dependency matrix, which reflects a desired power generation distribution between different wind turbines of the plurality of wind turbines, is determined. A power reference vector is calculated by multiplying the dependency matrix with the setpoint vector, such that the power reference vector comprises a coordinated power setpoint for each wind turbine. The operation of the wind farm is controlled based on the calculated power reference vector. A superordinate control system, a wind farm, a computer-readable medium and a program element, which are adapted for performing and/or for controlling the above described wind farm operation control method are further disclosed.
    Type: Grant
    Filed: January 18, 2011
    Date of Patent: November 25, 2014
    Assignee: Siemens Aktiengesellschaft
    Inventors: Per Egedal, Ramakrishnan Krishna
  • Publication number: 20140025788
    Abstract: A system may include a discovery engine to perform a discovery process on a network of multiple configuration items and to populate a data structure with information about each discovered configuration item in the network. The information may include a configuration parameter for each configuration item and a metric to be monitored for the configuration item.
    Type: Application
    Filed: July 18, 2012
    Publication date: January 23, 2014
    Inventors: Ramakrishnan Krishna MAHADEVAN, Pargaonkar VISHWANATH
  • Publication number: 20130187383
    Abstract: It is described an arrangement for determining a target value of an operational variable of a wind turbine, the arrangement comprising: at least one input terminal for receiving at least one operational parameter of the wind turbine; a determining unit adapted to determine a target value of an operational variable of the wind turbine based on the operational parameter. Further, a corresponding method and a wind turbine are described.
    Type: Application
    Filed: July 31, 2012
    Publication date: July 25, 2013
    Inventors: Thomas Esbensen, Gustav Hoegh, Ramakrishnan Krishna
  • Publication number: 20130161952
    Abstract: A method for controlling a wind turbine with a rotor and at least one rotor blade, and a control unit are disclosed. The method is characterised in adjusting a pitch angle of the rotor blade and determining the limit of an input value based on the adjusted pitch angle, wherein the input value includes information about the turbine rotational speed.
    Type: Application
    Filed: December 18, 2012
    Publication date: June 27, 2013
    Inventors: Martin Huus Bjerge, Per Egedal, Gustav Hoegh, Ramakrishnan Krishna, Hans Laurberg
  • Publication number: 20130156577
    Abstract: A method of controlling a wind turbine is provided. The method includes the steps of obtaining a number of operating values relevant to a wind turbine, calculating a thrust setpoint on the basis of the operating values, and controlling a wind turbine according to a thrust setpoint. A wind park controller, a wind turbine controller, and a wind park are also provided.
    Type: Application
    Filed: November 30, 2012
    Publication date: June 20, 2013
    Inventors: Thomas Esbensen, Gustav Hoegh, Ramakrishnan Krishna
  • Publication number: 20120078518
    Abstract: A method of determining an estimated wind speed of a wind driving a wind turbine includes measuring a current power generated by the wind turbine, measuring a current rotor speed of a rotor of the wind turbine, and measuring a current blade pitch angle of a rotor blade of the rotor. Moreover, the method includes determining the estimated wind speed based on the current power, the current rotor speed and the current blade pitch angle.
    Type: Application
    Filed: September 22, 2009
    Publication date: March 29, 2012
    Inventor: Ramakrishnan Krishna
  • Publication number: 20110175353
    Abstract: A method for controlling the operation of a wind farm with a plurality of wind turbines is disclosed A setpoint vector is defined, wherein each component of the setpoint vector represents an individual power setpoint of one of the plurality of wind turbines. A dependency matrix, which reflects a desired power generation distribution between different wind turbines of the plurality of wind turbines, is determined. A power reference vector is calculated by multiplying the dependency matrix with the setpoint vector, such that the power reference vector comprises a coordinated power setpoint for each wind turbine. The operation of the wind farm is controlled based on the calculated power reference vector. A superordinate control system, a wind farm, a computer-readable medium and a program element, which are adapted for performing and/or for controlling the above described wind farm operation control method are further disclosed.
    Type: Application
    Filed: January 18, 2011
    Publication date: July 21, 2011
    Inventors: Per Egedal, Ramakrishnan Krishna