Method, apparatus and system for suppressing low frequency oscillation in power system

Patent metadata

Field	Value
Publication number	US-9450411-B2
Application number	US-201113881577-A
Country	US
Kind code	B2
Filing date	Oct 14, 2011
Priority date	Oct 26, 2010
Publication date	Sep 20, 2016
Grant date	Sep 20, 2016

Abstract

A method, apparatus and system for suppressing low frequency oscillation in a power system. The method includes determining a system transfer function of an interconnected power system section in which a variable frequency transformer (VFT) is located; determining a damping controller parameters according to the system transfer function; and suppressing low frequency oscillation of the power system by means of the VFT based on the damping controller parameter. The objects of the method, apparatus and system are definite: optimizing the damping controller parameter can be achieved by simply tracking and analyzing the response of the system to disturbance, without the need to understand the configuration and parameters of the system or solve complicated power system equations, which has a better effect in suppressing low frequency oscillation in the power system and is advantageous for improving the safety and stability level of the power grid.

First claim

What is claimed is:

1. A method for suppressing low frequency oscillation in a power system, comprising:
determining, by at least one processor, a system transfer function at a cross-section of the interconnected power system where a variable frequency transformer (VFT) locates;
determining, by the at least one processor, damping controller parameters according to the system transfer function; and
suppressing, by the VFT, low frequency oscillation in the power system based on the damping controller parameters,
wherein determining a system transfer function at a cross-section of the interconnected power system comprises:
applying, by the VFT, a power disturbance at the cross-section of the interconnected power system where the VFT locates;
measuring, by the at least one processor, a power response under the power disturbance at the cross-section of the interconnected power system where the VFT locates; and
determining, by the at least one processor, the system transfer function using a Prony method according to the power response.

2. The method for suppressing low frequency oscillation in a power system according to claim 1 , wherein applying a power disturbance at the cross-section of the interconnected power system where the VFT locates comprises:
applying, by the VFT, a square-wave power disturbance at the cross-section of the interconnected power system where the VFT locates.

3. The method for suppressing low frequency oscillation in a power system according to claim 1 , wherein determining damping controller parameters according to the system transfer function comprises:
determining, by the at least one processor, the damping controller parameters according to the system transfer function using a root locus method and phase compensation method.

4. The method for suppressing low frequency oscillation in a power system according to claim 1 , wherein after determining the damping controller parameters, the method further comprises:
applying, by the VFT, a power disturbance at the cross-section of the interconnected power system with parallel AC line(s) where the VFT locates to optimize the damping controller parameters.

5. The method for suppressing low frequency oscillation in a power system according to claim 1 , wherein determining damping controller parameters according to the system transfer function comprises:
performing, by the at least one processor, DC-blocking and phase lead/lag compensation.

6. A system for suppressing low frequency oscillation in a power system, comprising: at least one processor and a variable frequency transformer (VFT),
wherein the at least one processor is configured to:
determine a system transfer function at a cross-section of the interconnected power system where the VFT locates; and
determine damping controller parameters according to the system transfer function,

wherein the VFT is configured to:
apply a power disturbance at the cross-section of the interconnected power system where the VFT locates; and
suppress low frequency oscillation in the power system based on the damping controller parameters, and

wherein the at least one processor is further configured to:
measure a power response under the power disturbance at the cross-section of the interconnected power system where the VFT locates; and
determine the system transfer function using a Prony method according to the power response.

7. The system for suppressing low frequency oscillation in a power system according to claim 6 , wherein the VFT is configured to apply a square-wave power disturbance with parallel AC lines at the cross-section of the interconnected power system where the VFT locates.

8. The system for suppressing low frequency oscillation in a power system according to claim 6 , wherein the at least one processor is configured to determine damping controller parameters according to the system transfer function using a root locus method and phase compensation method.

9. The system for suppressing low frequency oscillation in a power system according to claim 6 ,
wherein the VFT is configured to apply a power disturbance at the cross-section of the interconnected power system with parallel AC lines where the VFT locates to optimize the damping controller parameters.

10. The system for suppressing low frequency oscillation in a power system according to claim 6 , wherein the at least one processor is configured to perform DC-blocking module and phase lead/lag compensation.

11. A method for suppressing low frequency oscillation in a power system, comprising:
determining, by at least one processor, a system transfer function at a cross-section of the interconnected power system where a variable frequency transformer (VFT) locates;
determining, by the at least one processor, damping controller parameters according to the system transfer function;
suppressing, by the VFT, low frequency oscillation in the power system based on the damping controller parameters,
wherein determining a system transfer function at a cross-section of the interconnected power system comprises:
applying, by the VFT, a square-wave power disturbance at the cross-section of the interconnected power system where the VFT locates; and
measuring, by the at least one processor, a power response under the power disturbance at the cross-section of the interconnected power system where the VFT locates.

12. A method for suppressing low frequency oscillation in a power system, comprising:
determining, by at least one processor, a system transfer function at a cross-section of the interconnected power system where a variable frequency transformer (VFT) locates;
determining, by the at least one processor, damping controller parameters according to the system transfer function using a root locus method and phase compensation method;
suppressing, by the VFT, low frequency oscillation in the power system based on the damping controller parameters.

13. A system for suppressing low frequency oscillation in a power system, comprising: at least one processor and a variable frequency transformer (VFT),
wherein the at least one processor is configured to:
determine a system transfer function at a cross-section of the interconnected power system where the VFT locates; and
determine damping controller parameters according to the system transfer function,

wherein the VFT is configured to:
apply a square-wave power disturbance with parallel AC lines at the cross-section of the interconnected power system where the VFT locates; and
suppress low frequency oscillation in the power system based on the damping controller parameters, and

wherein the at least one processor is further configured to:
measure a power response under the power disturbance at the cross-section of the interconnected power system where the VFT locates.

14. A system for suppressing low frequency oscillation in a power system, comprising: at least one processor and a variable frequency transformer (VFT),
wherein the at least one processor is configured to:
determine a system transfer function at a cross-section of the interconnected power system where the VFT locates; and
determine damping controller parameters according to the system transfer function using a root locus method and phase compensation method,

wherein the VFT is configured to:
suppress low frequency oscillation in the power system based on the damping controller parameters.

Assignees

• Chen Gesong
• Zhou Xiaoxin
• Song Ruihua
• State Grid Corp China

Inventors

• Chen Gesong
• Zhou Xiaoxin
• Song Ruihua

Classifications

• H02J3/00142 Primary

  Oscillations concerning frequency · CPC title

• H02J3/24 Primary

  Electricity · mapped topic