Synchrophasor measurement method for power systems

Patent metadata

Field	Value
Publication number	US-10191094-B2
Application number	US-201715609484-A
Country	US
Kind code	B2
Filing date	May 31, 2017
Priority date	May 31, 2017
Publication date	Jan 29, 2019
Grant date	Jan 29, 2019

Abstract

A synchrophasor measurement method for a device configured to take synchronized measurements in a power system is provided. The synchrophasor measurement method includes receiving global positioning system (GPS)-synchronized samples of a signal sensed by the device from the power system; determining a level of distortion of the signal; selecting, based on the level of distortion, a computation method, the computation method being one of an improved zero-crossing (IZC) method and an enhanced phase-lock-loop (EPLL) method; performing the selected computation method to determine at least one parameter of the signal at a reporting frequency, which is at least twice a line frequency of the power system; and outputting, at the reporting frequency, the at least one parameter to an operator of the power system to allow the operator to perform at least one of a monitoring and a controlling of at least one element of the power system.

First claim

What is claimed is:

1. A synchrophasor measurement method for a device configured to take synchronized measurements in a power system, comprising:
receiving global positioning system (GPS)-synchronized samples of a signal sensed by the device from the power system;
determining a level of distortion of the signal;
selecting, based on the level of distortion, a computation method, the computation method being one of an improved zero-crossing (IZC) method and an enhanced phase-lock-loop (EPLL) method;
performing the selected computation method to determine at least one parameter of the signal at a reporting frequency, which is at least twice a line frequency of the power system; and
outputting, at the reporting frequency, the at least one parameter to an operator of the power system to allow the operator to perform at least one of a monitoring and a controlling of at least one element of the power system.

2. The synchrophasor measurement method of claim 1 , wherein the signal is one of a voltage and a current signal.

3. The synchrophasor measurement method of claim 1 , wherein the determining the level of distortion comprises computing a total harmonic distortion of the signal.

4. The synchrophasor measurement method of claim 1 , wherein performing the IZC method comprises:
representing a vector x of a subset of the samples in the form of x=αM, α being a vector of a first coefficient and a second coefficient, and M being a constant-valued matrix;
performing a pseudo-inverse computation α=[M T M] −1 M T x to determine the first coefficient and the second coefficient;
interpolating between the subset of the samples, using the first coefficient and the second coefficient, to generate a polynomial function;
determining a zero-crossing location as a point where the polynomial function is zero;
repeating, for subsequent subsets of the samples, the representing, performing, interpolating, and determining steps to determine subsequent zero-crossing locations; and
computing, after determining each zero-crossing location, the at least one parameter of the signal based on at least the last three subsequent zero-crossing locations.

5. The synchrophasor measurement method of claim 1 , further comprising, when performing the IZC method, setting a sampling rate of the device to 100 kHz.

6. The synchrophasor measurement method of claim 1 , wherein performing the EPLL method comprises:
initializing a magnitude, a phase angle, an angular frequency, and a direct-current (DC) offset of an estimated signal;
generating the estimated signal with the magnitude, phase angle, angular frequency, and DC offset;
determining an error between the estimated signal and the signal sensed by the device;
updating, based on the error, the magnitude, the phase angle, the angular frequency, and the DC offset;
calculating a frequency of the estimated signal based on the updated angular frequency;
providing at least one the calculated frequency and the updated magnitude, phase angle, angular frequency, and DC offset as the at least one parameter; and
repeating, for every new sample of the signal sensed by the device, the generating, determining, updating, calculating, and providing steps.

7. The synchrophasor measurement method of claim 6 , further comprising iteratively performing the generating, determining, updating, and calculating steps for a predetermined number of iterations prior to the providing step.

8. The synchrophasor measurement method of claim 1 , further comprising, when performing the EPLL method, setting a sampling rate of the device to between 720 Hz and 36 kHz.

9. The synchrophasor measurement method of claim 1 , wherein the at least one parameter includes at least one of a magnitude, a frequency, a phase angle, an angular frequency, and a DC offset.

10. The synchrophasor measurement method of claim 1 , wherein the at least one element of the power system includes at least one of a generator, a switch, a transformer, a transmission line, and a power-consuming load.

11. An electronic device for a power system, comprising:
a sensor;
a global positioning system (GPS) receiver;
one or more processors; and
memory storing instructions adapted to be executed by the one or more processors to perform operations comprising:
receiving samples of a signal sensed by the sensor from the power system, the samples being synchronized to an output of the GPS receiver;
determining a level of distortion of the signal;
selecting, based on the level of distortion, a computation method, the computation method being one of an improved zero-crossing (IZC) method and an enhanced phase-lock-loop (EPLL) method;
performing the selected computation method to determine at least one parameter of the signal at a reporting frequency, which is at least twice a line frequency of the power system; and
outputting, at the reporting frequency, the at least one parameter to an operator of the power system to allow the operator to perform at least one of a monitoring and a controlling of at least one element of the power system.

12. The electronic device of claim 11 , wherein the signal is one of a voltage and a current signal.

13. The electronic device of claim 11 , wherein the operation of determining the level of distortion comprises computing a total harmonic distortion of the signal.

14. The electronic device of claim 11 , wherein the operation of performing the IZC method comprises:
representing a vector x of a subset of the samples in the form of x=αM, α being a vector of a first coefficient and a second coefficient, and M being a constant-valued matrix;
performing a pseudo-inverse computation α=[M T M] −1 M T x to determine the first coefficient and the second coefficient;
interpolating between the subset of the samples, using the first coefficient and the second coefficient, to generate a polynomial function;
determining a zero-crossing location as a point where the polynomial function is zero;
repeating, for subsequent subsets of the samples, the representing, performing, interpolating, and determining steps to determine subsequent zero-crossing locations; and computing, after determining each zero-crossing location, the at least one parameter of the signal based on at least the last three subsequent zero-crossing locations.

15. The electronic device of claim 11 , the operations further comprising, when performing the IZC method, setting a sampling rate of the electronic device to 100 kHz.

16. The electronic device of claim 11 , wherein the operation of performing the EPLL method comprises:
initializing a magnitude, a phase angle, an angular frequency, and a direct-current (DC) offset of an estimated signal;
generating the estimated signal with the magnitude, phase angle, angular frequency, and DC offset;
determining an error between the estimated signal and the signal sensed by the device;
updating, based on the error, the magnitude, the phase angle, the angular frequency, and the DC offset;
calculating a frequency of the estimated signal based on the updated angular frequency;
providing at least one the calculated frequency and the updated magnitude, phase angle, angular frequency, and DC offset as the at least one parameter; and
repeating, for every new sample of the signal sensed by the sensor, the generating, determining, updating, calculating, and providing steps.

17. The electronic device of claim 16 , the operations further comprising iteratively performing the generating, determining, updating, and calculating steps for a predetermined number of iterations prior to the

Assignees

• Univ Tennessee Res Found
• Ut Battelle Llc

Inventors

• Yao Wenxuan
• Zhao Jiecheng
• Liu Yilu
• Herron Andrew N
• King Daniel J
• King Jr Thomas J
• Zhan Lingwei

Classifications

• G01R19/2513 Primary

  Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging · CPC title

• Y02E60/00

  Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation · CPC title

• Y02E40/70

  Smart grids as climate change mitigation technology in the energy generation sector · CPC title

• Y04S10/22

  Flexible AC transmission systems [FACTS] or power factor or reactive power compensating or correcting units · CPC title