Patents by Inventor Stefan Roxenborg
Stefan Roxenborg 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).
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Patent number: 10962604Abstract: An arrangement for injection-based ground fault protection handling including a number of stator windings of an electric machine that are connected to a neutral point, a first transformer including at least one primary winding connected to at least one measurement point of the stator windings and at least one secondary winding for measuring an electrical quantity of the machine at the measurement point. There is also a second transformer having a primary winding connected between the neutral point and a ground potential and a secondary winding for connection to a signal generation and detection unit in order to inject a signal into the neutral point and receive a response. The impedance of the second transformer is in the range of the impedance of the machine.Type: GrantFiled: July 31, 2019Date of Patent: March 30, 2021Assignee: ABB SCHWEIZ AGInventors: Stefan Roxenborg, Zoran Gajic, Tord Bengtsson, Mikael Sehlstedt
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Publication number: 20200103453Abstract: An arrangement for injection-based ground fault protection handling including a number of stator windings of an electric machine that are connected to a neutral point, a first transformer including at least one primary winding connected to at least one measurement point of the stator windings and at least one secondary winding for measuring an electrical quantity of the machine at the measurement point. There is also a second transformer having a primary winding connected between the neutral point and a ground potential and a secondary winding for connection to a signal generation and detection unit in order to inject a signal into the neutral point and receive a response. The impedance of the second transformer is in the range of the impedance of the machine.Type: ApplicationFiled: July 31, 2019Publication date: April 2, 2020Inventors: Stefan Roxenborg, Zoran Gajic, Tord Bengtsson, Mikael Sehlstedt
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Patent number: 10254155Abstract: A monitoring device and a method for detecting mechanical torsional oscillations in a rotor shaft of a turbine-generator system. Specifically, the monitoring device and a method for detecting mechanical torsional oscillations in a turbine-generator system having a plurality of, such as two, three, four, five, six or more, turbines that are interconnected by means of a common turbine shaft.Type: GrantFiled: September 5, 2014Date of Patent: April 9, 2019Assignee: ABB Schweiz AGInventors: Tord Bengtsson, Zoran Gajic, Stefan Roxenborg
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Publication number: 20170276539Abstract: A monitoring device and a method for detecting mechanical torsional oscillations in a rotor shaft of a turbine-generator system. Specifically, the monitoring device and a method for detecting mechanical torsional oscillations in a turbine-generator system having a plurality of, such as two, three, four, five, six or more, turbines that are interconnected by means of a common turbine shaft.Type: ApplicationFiled: September 5, 2014Publication date: September 28, 2017Inventors: Tord BENGTSSON, Zoran GAJIC, Stefan ROXENBORG
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Patent number: 9075099Abstract: A method for adapting a ground fault detection to a change of an electrical machine condition, wherein the machine includes a winding. The electrical machine is in a first machine condition, a first reference value being defined for measured values of an electrical quantity. The ground fault detection includes continuously measuring the electrical quantity in the winding and detecting a ground fault based on the measured values of the electrical quantity and the first reference value. The method includes receiving a signal, detecting a change of machine condition based on the received signal, and changing to a second reference value for the measured values of the electrical quantity, the second reference value being different from the first reference value when the change of machine condition is detected.Type: GrantFiled: March 3, 2011Date of Patent: July 7, 2015Assignee: ABB RESEARCH LTD.Inventors: Henrik Johansson, Joseph Menezes, Stefan Roxenborg, Tord Bengtsson
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Patent number: 9041383Abstract: A method for linearizing voltage transmission through a transformer including a magnetic core and, input and output windings. A measurement signal is supplied to the input winding at a first frequency and an output signal is measured at the output winding of the transformer, wherein the voltage of the measurement signal may be so low that the transformer operates in a non-linear region. The method includes, for a conditioning signal, selecting a second frequency different from the first frequency, defining an amplitude value of the conditioning signal and supplying the conditioning signal to the input winding at the second frequency with the defined amplitude value so that the transformer operates in its linear region.Type: GrantFiled: September 18, 2013Date of Patent: May 26, 2015Assignee: ABB Research Ltd.Inventors: Tord Bengtsson, Henrik Johansson, Stefan Roxenborg, Joseph Menezes, Zoltan Nagy, Mikael Sehlstedt
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Patent number: 9018960Abstract: A method for enhancing the reliability of generator ground fault detection based on a signal injection scheme, wherein the generator includes a winding. The method includes injecting a test signal at a predefined frequency to the winding, measuring an electrical quantity of a response signal in the winding resulted from the injected test signal, and detecting a ground fault based on the measured value of the electrical quantity. The method further includes continuously determining the frequency of the response signal, and discarding the present measured value corresponding to the determined frequency when the determined frequency deviates from the predefined frequency with a first threshold value.Type: GrantFiled: August 21, 2013Date of Patent: April 28, 2015Assignee: ABB Research Ltd.Inventors: Henrik Johansson, Joseph Menezes, Stefan Roxenborg, Tord Bengtsson
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Patent number: 8924170Abstract: A device for detecting a failed rectifier in an AC/DC converter for converting three-phase AC power to DC power and having its AC side connected to a three-phase AC source and its DC side connected to a DC load, the AC/DC converter including a rectifier circuit including at least three legs, each of the legs connected to a corresponding AC phase and including at least one rectifier, the device including a measuring unit for measuring and sampling AC current for each of the phases and a calculating unit configured to estimate an instantaneous DC current based on the measured instantaneous AC currents during one period of the power supply frequency.Type: GrantFiled: March 28, 2014Date of Patent: December 30, 2014Assignee: ABB Research Ltd.Inventors: Tord Bengtsson, Stefan Roxenborg
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Publication number: 20140214343Abstract: A device for detecting a failed rectifier in an AC/DC converter for converting three-phase AC power to DC power and having its AC side connected to a three-phase AC source and its DC side connected to a DC load, the AC/DC converter including a rectifier circuit including at least three legs, each of the legs connected to a corresponding AC phase and including at least one rectifier, the device including a measuring unit for measuring and sampling AC current for each of the phases and a calculating unit configured to estimate an instantaneous DC current based on the measured instantaneous AC currents during one period of the power supply frequency.Type: ApplicationFiled: March 28, 2014Publication date: July 31, 2014Inventors: Tord Bengtsson, Stefan Roxenborg
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Publication number: 20140015510Abstract: A method for linearizing voltage transmission through a transformer including a magnetic core and, input and output windings. A measurement signal is supplied to the input winding at a first frequency and an output signal is measured at the output winding of the transformer, wherein the voltage of the measurement signal may be so low that the transformer operates in a non-linear region. The method includes, for a conditioning signal, selecting a second frequency different from the first frequency, defining an amplitude value of the conditioning signal and supplying the conditioning signal to the input winding at the second frequency with the defined amplitude value so that the transformer operates in its linear region.Type: ApplicationFiled: September 18, 2013Publication date: January 16, 2014Inventors: Tord Bengtsson, Henrik Johansson, Stefan Roxenborg, Joseph Menezes, Zoltan Nagy, Mikael Sehlstedt
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Publication number: 20130335097Abstract: A method for enhancing the reliability of generator ground fault detection based on a signal injection scheme, wherein the generator includes a winding. The method includes injecting a test signal at a predefined frequency to the winding, measuring an electrical quantity of a response signal in the winding resulted from the injected test signal, and detecting a ground fault based on the measured value of the electrical quantity. The method further includes continuously determining the frequency of the response signal, and discarding the present measured value corresponding to the determined frequency when the determined frequency deviates from the predefined frequency with a first threshold value.Type: ApplicationFiled: August 21, 2013Publication date: December 19, 2013Inventors: Henrik Johansson, Joseph Menezes, Stefan Roxenborg, Tord Bengtsson
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Publication number: 20130335098Abstract: A method for adapting a ground fault detection to a change of an electrical machine condition, wherein the machine includes a winding. The electrical machine is in a first machine condition, a first reference value being defined for measured values of an electrical quantity. The ground fault detection includes continuously measuring the electrical quantity in the winding and detecting a ground fault based on the measured values of the electrical quantity and the first reference value. The method includes receiving a signal, detecting a change of machine condition based on the received signal, and changing to a second reference value for the measured values of the electrical quantity, the second reference value being different from the first reference value when the change of machine condition is detected.Type: ApplicationFiled: March 3, 2011Publication date: December 19, 2013Inventors: Henrik Johansson, Joseph Menezes, Stefan Roxenborg, Tord Bengtsson
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Patent number: 8472156Abstract: A method and a device for supervising the sensitivity of a protection function in an electrical power system including a metering device for measuring values of a feature, said protection function being configured to initialize an action based on a test value and a threshold value for the feature, wherein said test value is either a measured value or derived from the said measured values, the device includes a computing unit configured to receive the test values and, repeatedly during the operation of the protection function, to calculate a mean value and a deviation of the test values, to determine the probability of a false action based on the calculated mean value, the threshold value and the calculated deviation, and to indicate that the sensitivity is too high when the probability of a false action exceeds a first limit value for the probability of a false action.Type: GrantFiled: October 24, 2011Date of Patent: June 25, 2013Assignee: ABB Research Ltd.Inventors: Stefan Thorburn, Henrik Johansson, Stefan Roxenborg, Tord Bengtsson
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Publication number: 20120099233Abstract: A method and a device for supervising the sensitivity of a protection function in an electrical power system including a metering device for measuring values of a feature, said protection function being configured to initialize an action based on a test value and a threshold value for the feature, wherein said test value is either a measured value or derived from the said measured values, the device includes a computing unit configured to receive the test values and, repeatedly during the operation of the protection function, to calculate a mean value and a deviation of the test values, to determine the probability of a false action based on the calculated mean value, the threshold value and the calculated deviation, and to indicate that the sensitivity is too high when the probability of a false action exceeds a first limit value for the probability of a false action.Type: ApplicationFiled: October 24, 2011Publication date: April 26, 2012Inventors: Stefan Thorburn, Henrik Johansson, Stefan Roxenborg, Tord Bengtsson
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Patent number: 8095326Abstract: A method to predict a state of a power system and a device to perform the method are presented, where the method includes the step of performing a Fast Fourier Transform on samples of a periodic waveform signal in order to determine a frequency spectrum of the signal, where the signal was derived from at least one measurable electric quantity of the power system and is representative for the state of the power system. Frequencies and related complex amplitudes at selected peaks in the frequency spectrum are determined and stored together with a time stamp. Afterwards, a predicted value of the periodic waveform signal in the time domain is determined at a prediction time by calculating a sum of sinusoidal signals at the prediction time, where each of the sinusoidal signals is characterized by one of the determined frequencies and its related complex amplitude as well as the time stamp.Type: GrantFiled: December 8, 2009Date of Patent: January 10, 2012Assignee: ABB Research Ltd.Inventors: Bertil Berggren, Tord Bengtsson, Stefan Roxenborg
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Publication number: 20100088048Abstract: A method to predict a state of a power system and a device to perform the method are presented, where the method includes the step of performing a Fast Fourier Transform on samples of a periodic waveform signal in order to determine a frequency spectrum of the signal, where the signal was derived from at least one measurable electric quantity of the power system and is representative for the state of the power system. Frequencies and related complex amplitudes at selected peaks in the frequency spectrum are determined and stored together with a time stamp. Afterwards, a predicted value of the periodic waveform signal in the time domain is determined at a prediction time by calculating a sum of sinusoidal signals at the prediction time, where each of the sinusoidal signals is characterized by one of the determined frequencies and its related complex amplitude as well as the time stamp.Type: ApplicationFiled: December 8, 2009Publication date: April 8, 2010Inventors: Bertil Berggren, Tord Bengtsson, Stefan Roxenborg