ROBERT KENT SMITH
Physical Therapy in Spangsville, PA
License number
Pennsylvania TE001898L
Category
Physical Therapy
Type
Physical Therapist Assistant
Address
Address
Spangsville, PA 19512
Personal information
See more information about ROBERT KENT SMITH at radaris.comName
Address
Phone
509 Sunnyside Ave, Eagleville, PA 19403
508 Waters Edge, Newtown Sq, PA 19073
50 E Summit Dr, Stevens, PA 17578
509 Virginia Ave, Phoenixville, PA 19460
507 E Mill Rd, Flourtown, PA 19031
Professional information
System And Method For Phasor Estimation And Frequency Tracking In Digital Protection Systems
US Patent:
5721689, Feb 24, 1998
Filed:
Dec 18, 1995
Appl. No.:
8/574357
Inventors:
David Hart - Raleigh NC
Yi Hu - Cary NC
Damir Novosel - Cary NC
Robert Smith - Boyertown PA
Yi Hu - Cary NC
Damir Novosel - Cary NC
Robert Smith - Boyertown PA
Assignee:
ABB Power T&D Company Inc. - Raleigh NC
International Classification:
G01R 2310, H03M 100
US Classification:
364484
Abstract:
A method and system for estimating phasors and tracking the frequency of a signal is provided. The method uses a variable N-point DFT to compute one or more phasors based on data acquired from one or more sampled signals. At each sampling interval the change in phasor angle between the current sampling interval and the previous sampling interval is determined and used to estimate the instantaneous frequency of the signal. Instantaneous frequencies are averaged over a cycle of the signal. In addition, a number of discrete frequencies and corresponding DFT windows based on a fixed sampling rate and a predetermined fundamental frequency of the signal are defined and used in estimating the instantaneous frequency. Once the average cycle frequency is determined the DFT window is adjusted by setting it equal to the DFT window corresponding to the discrete frequency closest to the average cycle frequency.
Digital Integrator V/Hz Relay For Generator And Transformer Over-Excitation Protection
US Patent:
5671112, Sep 23, 1997
Filed:
May 13, 1996
Appl. No.:
8/647589
Inventors:
Yi Hu - Cary NC
David Hart - Raleigh NC
Damir Novosel - Cary NC
Robert Smith - Boyertown PA
David Hart - Raleigh NC
Damir Novosel - Cary NC
Robert Smith - Boyertown PA
Assignee:
ABB Power T&D Company, Inc. - Raleigh NC
International Classification:
H02H 318
US Classification:
361 86
Abstract:
A system for implementing accurate V/Hz value measurement and trip time determination for generator/transformer overexcitation protection independent of the conventional frequency tracking and phasor estimation based on Discrete Fourier Transformation (DFT) techniques. A sampled sinusoidal voltage signal is passed through a digital integrator and the magnitude of the digital integrator's output is measured as representative of the V/Hz ratio. The digital integrator is implemented in software using a difference equation in a generator protection unit. The technique may be used with either a fixed or a variable sampling frequency. When the sampling frequency is variable, the filter coefficients of the digital integrator are recalculated on-line each time the sampling frequency is changed, and a new value for the peak magnitude of the output of the digital integrator is calculated using the recalculated filter coefficients. Non-linear frequency response characteristics of the voltage sensors and non-ideal characteristics of the digital integrator are also adjusted using the measured frequency and error-frequency characteristics of the particular digital integrator and voltage sensors used.