System and method for impedance measurement using chirp signal injection

Patent metadata

Field	Value
Publication number	US-9618555-B2
Application number	US-201313953981-A
Country	US
Kind code	B2
Filing date	Jul 30, 2013
Priority date	Jul 30, 2012
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

A method for impedance measurement using chirp signal injection is provided. The method includes injecting at least one chirp signal into the three-phase AC system, and collecting at least one response to the at least one chirp signal. The method further includes transferring the at least one response from abc coordinates to dq coordinates. At least one impedance is calculated based on the at least one response to the at least one chirp signal.

First claim

What is claimed is:

1. A method of impedance measurement for a three-phase alternating current (AC) system, comprising:
connecting an injection circuit of an impedance measurement unit to the three-phase AC system, the injection circuit comprising a voltage source inverter configured for drawing power from the three-phase AC system to charge a capacitor and for using discharged power from the capacitor to inject chirp signals into the three-phase AC system;
injecting by the injection circuit at least one chirp signal into the three-phase AC system;
collecting by a collection circuit of the impedance measurement unit at least one response to the at least one chirp signal;
transferring by an instrumentation platform computer the at least one response from three-phase (abc) coordinates to direct and quadrature (dq) coordinates; and
calculating by a control circuit at least one impedance of the three-phase AC system based on the at least one response to the at least one chirp signal.

2. The method of claim 1 , wherein the at least one chirp signal includes one of the set consisting of a d-axis chirp signal and a q-axis chirp signal.

3. The method of claim 1 , wherein the at least one chirp signal includes a d-axis chirp signal and a q-axis chirp signal.

4. The method of claim 3 , wherein at least one of the d-axis chirp signal and the q-axis chirp signal is of the form:

x
⁡

(
t
)

=

sin
(

2
⁢

π
(

f
0

+

f
1

-

f
0

2
⁢

⁢
T

⁢
t

)

⁢
t

)

,

where f 0 is a start frequency, f 1 is an end frequency, T is a duration of at least one of the d-axis chirp signal and the q-axis chirp signal, and t is a time.

5. The method of claim 1 , wherein the action of transferring the at least one response from abc coordinates to dq coordinates comprises:
transforming an AC voltage response to direct current (DC) voltage components; and
transforming an AC current response to DC current components.

6. The method of claim 1 , wherein the action of calculating the impedances of the three-phase AC system comprises:
identifying frequency points of interest; and
calculating impedance at each frequency point of interest.

7. The method of claim 1 , further comprising:
generating a virtual perturbation signal through an injection transfer function matrix; and
collecting a response to the virtual perturbation signal,

wherein the action of calculating at least one impedance includes calculating an impedance based on the response to the virtual perturbation signal and the at least one response to the at least one chirp signal.

8. The method of claim 7 , wherein the action of generating a virtual perturbation signal through an injection transfer function matrix comprises:
generating the virtual perturbation signal using the equation

G
inj

⁡

(
s
)

=

[

G
injd

⁡

(
s
)

G
injq

⁡

(
s
)

]

,

where G inj (s) is the injection transfer function matrix, G injd (s) is a d-axis injection transfer function, and G injq (s) is a q-axis injection transfer function.

9. The method of claim 8 , wherein the action of generating a virtual perturbation signal through an injection transfer function matrix comprises:
generating two independent perturbation signals using the equations
G inj1 ( s )=[ A 1 B 1 ] T , G inj2 ( s )=[ A 2 B 2 ] T ,

where G inj1 (s) is a first injection transfer function matrix, G inj2 (s) is a second injection transfer function matrix, G inj1 is a first transfer function, G inj2 is a second transfer function, A 1 is a first element in the transfer function G inj1 , A 2 is a first element in the transfer function G inj2 , B 1 is a second element in the transfer function G inj1 , B 2 is a second element in the transfer function G inj2 , and T is a transpose symbol.

10. The method of claim 9 , wherein matrices [A 1 B 1 ] T and [A 2 B 2 ] T are vectors.

11. The method of claim 10 , wherein the matrices [A 1 B 1 ] T and [A 2 B 2 ] T are independent and constant vectors.

12. A system for performing impedance measurement for a three-phase alternating current (AC) system, comprising:
an injection circuit comprising a voltage source inverter (VSI) connectable to the three-phase AC system and a capacitor, the VSI being configured for drawing power from the three-phase AC system to charge the capacitor and for using discharged power from the capacitor to inject at least one chirp signal into the three-phase AC system;
a collection circuit configured to collect at least one response to the at least one chirp signal;
a control unit configured to transfer the at least one response from three-phase (abc) coordinates to direct and quadrature (dq) coordinates and to calculat

Assignees

• Huntington Ingalls Inc
• Virginia Tech Intellectual Properties Inc
• Huntington Ingalls Incorporated

Inventors

• Verhulst Jacob
• Belkhayat Mohamed
• Shen Zhiyu
• Jaksic Marko
• Mattavelli Paolo
• Boroyevich Dushan

Classifications

• G01R27/16 Primary

  Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line · CPC title

• G01R29/26 Primary

  Measuring noise figure; Measuring signal-to-noise ratio · CPC title

• G01R27/02

  Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant (by measuring phase angle only G01R25/00) · CPC title