Converter station power set point analysis system and method

Patent metadata

Field	Value
Publication number	US-9450409-B2
Application number	US-201313922644-A
Country	US
Kind code	B2
Filing date	Jun 20, 2013
Priority date	Jun 20, 2013
Publication date	Sep 20, 2016
Grant date	Sep 20, 2016

Abstract

Converter stations have real and reactive power set points initially determined as part of a main loadflow analysis routinely performed on the AC power system connected to the converter stations. Viable real and/or reactive power set points for the converter stations can be identified by calculating real and/or reactive power set point candidates for the converter stations before the main loadflow analysis is performed again on the AC power system. The power set point candidates are calculated based on information determined as part of a previous iteration of the main loadflow analysis on the AC power system. The power set point candidates which violate an operating constraint imposed on the AC power system are identified, and a region of valid power set points is defined for the converter stations that excludes the power set point candidates which violate an operating constraint imposed on the AC power system.

First claim

What is claimed is:

1. A method of identifying viable real and/or reactive power set points for converter stations connecting a first power system to an AC second power system, the converter stations each having a real and reactive power set point initially determined as part of a main loadflow analysis periodically performed on the AC power system, the method comprising:
calculating real and/or reactive power set point candidates for each of the converter stations before the main loadflow analysis is performed again on the AC power system, the power set point candidates calculated based on information determined as part of a previous iteration of the main loadflow analysis on the AC power system, the power set point candidates further being calculated between periods of the main loadflow analysis;
identifying which of the power set point candidates violate an operating constraint imposed on the AC power system;
defining a region of valid power set points for the converter stations that excludes the power set point candidates which violate an operating constraint imposed on the AC power system; and
changing the real and/or reactive power set points for the converter stations to correspond to one of the power set point candidates in the region between periods of the main loadflow analysis and before performing another main loadflow analysis.

2. The method of claim 1 , wherein calculating the power set point candidates for the converter stations comprises:
determining different changes in the power set points for each of the converter stations; and
adding each of the different changes to the corresponding power set points for each of the converter stations to form a plurality of vectors of power set point candidates, each of the vectors including a different combination of power set point candidates for each of the converter stations.

3. The method of claim 2 , wherein defining the region of valid power set points for the converter stations comprises determining a convex hull that excludes the vectors of power set point candidates that result in a violation of an operating constraint imposed on the AC power system.

4. The method of claim 1 , wherein the region of valid power set points for the converter stations is defined responsive to a triggering event.

5. The method of claim 1 , wherein the region of valid power set points for the converter stations is redefined more than one time before the main loadflow analysis is performed again on the AC power system.

6. The method of claim 1 , wherein defining the region of valid power set points for the converter stations comprises determining a convex hull that excludes the power set point candidates that violate an operating constraint imposed on the AC power system.

7. The method of claim 1 , wherein identifying which of the power set point candidates violate an operating constraint imposed on the AC power system comprises:
performing a plurality of loadflow simulations before the main loadflow analysis is performed again on the AC power system, each of the loadflow simulations being performed by varying the converter station set points in accordance with a different combination of the power set point candidates; and
identifying each combination of the power set point candidates that results in one of the loadflow simulations violating an operating constraint imposed on the AC power system.

8. The method of claim 7 , wherein the region of valid power set points for the converter stations is defined by excluding each combination of the power set point candidates that results in one of the loadflow simulations violating an operating constraint imposed on the AC power system.

9. The method of claim 7 , wherein defining the region of valid power set points for the converter stations comprises determining a convex hull that excludes each combination of the power set point candidates that results in one of the loadflow simulations violating an operating constraint imposed on the AC power system.

10. The method of claim 1 , further comprising changing the set points of the converter stations to a combination of the power set point candidates included in the region of valid power set points for the converter stations, before the main loadflow analysis is performed again on the AC power system.

11. The method of claim 1 , further comprising defining one or more additional regions of valid power set points for the converter stations, each of the one or more additional regions of valid power set points being defined for a different contingency condition in either of the power systems and excluding the power set point candidates which violate an operating constraint imposed on the AC power system under the contingency condition.

12. A power flow analysis system for identifying viable real and/or reactive power set points for converter stations connecting a first power system to an AC second power system, the converter stations each having a real and reactive power set point initially determined as part of a main loadflow analysis periodically performed on the AC power system, the power flow analysis system comprising a processing circuit operable to:
calculate real and/or reactive power set point candidates for each of the converter stations before the main loadflow analysis is performed again on the AC power system, the power set point candidates calculated based on information determined as part of a previous iteration of the main loadflow analysis on the AC power system, the power set point candidates further being calculated between periods of the main loadflow analysis;
identify which of the plurality power set point candidates violate an operating constraint imposed on the AC power system;
define a region of valid power set points for the converter stations that excludes the power set point candidates which violate an operating constraint imposed on the AC power system; and
changing the real and/or reactive power set points for each of the converter stations to correspond to one of the power set point candidates in the region between periods of the main loadflow analysis and before performing another main loadflow analysis.

13. The power flow analysis system of claim 12 , wherein the power flow analysis system is included in a supervisory control and data acquisition system operable to perform the main loadflow analysis on the AC power system, and wherein the power flow analysis system is operable to communicate the region of valid power set points for the converter stations to a high level controller operable to change the set points of the converter stations by selecting a combination of the power set point candidates within the region of valid power set points communicated from the power flow analysis system, before the main loadflow analysis is performed again by the supervisory control and data acquisition system on the AC power system.

14. The power flow analysis system of claim 12 , wherein the first power system is an HVDC power system.

15. The power flow analysis system of claim 12 , wherein the first power system is a wind or solar farm and the AC power system is an AC electrical network.

16. The power flow analysis system of claim 12 , wherein the AC power system includes AC electrical networks and the second power system includes tie-lines for connecting the AC electrical networks.

17. The power flow analysis system of claim 12 , wherein the processing circuit is operable to calculate the power set point candidates for the converter stations by:
determining different changes in the power set points for each of the converter st

Assignees

• Abb Research Ltd

Inventors

• Das Debrup
• Nuqui Reynaldo
• Larsson Mats

Classifications

• Y02E60/60

  Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD] · CPC title

• H02J3/14 Primary

  by switching loads on to, or off from, the networks, e.g. progressively balanced loading · CPC title

• H02J3/36 Primary

  Arrangements for transfer of electric power between AC networks via high-voltage DC [HVDC] links; Arrangements for transfer of electric power between generators and networks via HVDC links · CPC title

• G06F1/3203

  Power management, i.e. event-based initiation of a power-saving mode · CPC title

• H02J3/34 Primary

  Arrangements for transfer of electric power between networks of substantially different frequency · CPC title