Patents by Inventor Sudi Xu

Sudi Xu 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: 11316501
    Abstract: A resampling method based on window function for flexible sampling rate conversion in broadband frequency measurement devices is described. The resampling algorithm can satisfy the requirements of different sampling rates. The frequency responses of the filter in the resampling model based on the Farrow structure are analyzed, and the design criterion of the filter in resampling model is considered. A fractional delay filter design model based on window function method is described. A fractional delay filter matrix, which is expressed by polynomial form, is constructed. Then the expression related to subfilter coefficients is obtained and subfilter coefficients are solved for by the least square method.
    Type: Grant
    Filed: November 5, 2021
    Date of Patent: April 26, 2022
    Assignee: North China Electric Power University
    Inventors: Hao Liu, Tianshu Bi, Jie Lin, Sudi Xu, Yongzhao Lao
  • Patent number: 11201604
    Abstract: A resampling method based on window function for flexible sampling rate conversion in broadband frequency measurement devices is described. The resampling algorithm can satisfy the requirements of different sampling rates. The frequency responses of the filter in the resampling model based on the Farrow structure are analyzed, and the design criterion of the filter in resampling model is considered. A fractional delay filter design model based on window function method is described. A fractional delay filter matrix, which is expressed by polynomial form, is constructed. Then the expression related to subfilter coefficients is obtained and subfilter coefficients are solved for by the least square method.
    Type: Grant
    Filed: March 29, 2021
    Date of Patent: December 14, 2021
    Assignee: North China Power Electric University
    Inventors: Hao Liu, Tianshu Bi, Jie Lin, Sudi Xu, Yongzhao Lao
  • Patent number: 11119129
    Abstract: An improved phasor estimation method for M-class phasor measurement units (PMUs) with a low computational burden is described. The method contains three steps: 1) A phasor measurement filter is designed by selecting parameters of Taylor weighted least square method to prioritize dynamic phasor accuracy and a high level of suppression on high-frequency interferences; 2) A finite impulse response lowpass filter is designed by the equal-ripple method is put forward to suppress low-frequency interferences; and 3) Phasor amplitude is corrected under off-nominal conditions.
    Type: Grant
    Filed: January 25, 2021
    Date of Patent: September 14, 2021
    Assignee: North China Electric Power University
    Inventors: Hao Liu, Tianshu Bi, Sudi Xu
  • Patent number: 10990720
    Abstract: A general design method for phasor estimation algorithms on different applications is described based on a complex finite impulse response (FIR) band-pass filter. To facilitate the design of the complex band-pass filter for different requirements and reduce the trial and error process, a design framework based on the error mathematical models is described. Using an absolute value inequality theorem, the general error models between the filter gain and the error limitations of all the valuables measured by phasor measurement units (PMUs) are established separately. The filter design criteria obtained by the error models can determine the passband and stopband gain range of complex band-pass filters.
    Type: Grant
    Filed: December 29, 2020
    Date of Patent: April 27, 2021
    Assignee: North China Electric Power University
    Inventors: Hao Liu, Tianshu Bi, Sudi Xu
  • Patent number: 10942204
    Abstract: An improved phasor estimation method for M-class phasor measurement units (PMUs) with a low computational burden is described. The method contains three steps: 1) A phasor measurement filter is designed by selecting parameters of Taylor weighted least square method to prioritize dynamic phasor accuracy and a high level of suppression on high-frequency interferences; 2) A finite impulse response lowpass filter is designed by the equal-ripple method is put forward to suppress low-frequency interferences; and 3) Phasor amplitude is corrected under off-nominal conditions.
    Type: Grant
    Filed: October 27, 2020
    Date of Patent: March 9, 2021
    Assignee: North China Electric Power University
    Inventors: Hao Liu, Tianshu Bi, Sudi Xu
  • Patent number: 10915677
    Abstract: A general design method for phasor estimation algorithms on different applications is described based on a complex finite impulse response (FIR) band-pass filter. To facilitate the design of the complex band-pass filter for different requirements and reduce the trial and error process, a design framework based on the error mathematical models is described. Using an absolute value inequality theorem, the general error models between the filter gain and the error limitations of all the valuables measured by phasor measurement units (PMUs) are established separately. The filter design criteria obtained by the error models can determine the passband and stopband gain range of complex band-pass filters.
    Type: Grant
    Filed: July 22, 2020
    Date of Patent: February 9, 2021
    Assignee: North China Electric Power University
    Inventors: Hao Liu, Tianshu Bi, Sudi Xu
  • Patent number: 10901014
    Abstract: A high-accuracy synchrophasor estimation algorithm for PMU calibration is disclosed. This method can construct a dynamic phasor fitting model. Then, an iterative solution algorithm based on nonlinear fitting can be used to estimate the phasor and frequency, which can include one parameter during the iterations. Moreover, a method is disclosed for calculating the ROCOF based on the least-squares method to improve the ROCOF dynamic accuracy.
    Type: Grant
    Filed: October 22, 2020
    Date of Patent: January 26, 2021
    Assignee: North China Electric Power University
    Inventors: Hao Liu, Tianshu Bi, Sudi Xu
  • Patent number: 10884038
    Abstract: A high-accuracy synchrophasor estimation algorithm for PMU calibration is disclosed. This method can construct a dynamic phasor fitting model. Then, an iterative solution algorithm based on nonlinear fitting can be used to estimate the phasor and frequency, which can include one parameter during the iterations. Moreover, a method is disclosed for calculating the ROCOF based on the least-squares method to improve the ROCOF dynamic accuracy.
    Type: Grant
    Filed: July 22, 2020
    Date of Patent: January 5, 2021
    Assignee: North China Electric Power University
    Inventors: Hao Liu, Tianshu Bi, Sudi Xu