Participation factor based method for resynchronization of microgrids

Patent metadata

Field	Value
Publication number	US-10044192-B2
Application number	US-201615017346-A
Country	US
Kind code	B2
Filing date	Feb 5, 2016
Priority date	Feb 5, 2016
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

A microgrid is re-synchronized to a main grid or substation by determining a degree of bus angle or frequency mismatch and bus voltage mismatch between the microgrid and the main grid or substation prior to re-synchronization, determining an amount of power adjustment needed to reduce the bus angle or frequency mismatch and bus voltage mismatch to below respective predetermined thresholds, determining at least one participation factor for each microgrid bus, each participation factor indicating an amount of influence power injection by the corresponding bus has on the bus angle or frequency mismatch or on the voltage mismatch, allocating the amount of power adjustment to the microgrid buses in proportion to the participation factors assigned to the buses, and re-synchronizing the microgrid to the main grid or substation responsive to the bus angle or frequency mismatch and bus voltage mismatch satisfying the respective predetermined thresholds.

First claim

What is claimed is:

1. A method of re-synchronizing a microgrid to a main grid or substation, the microgrid including a plurality of buses to which energy resources and loads are connected, the method comprising:
determining a degree of bus angle or frequency mismatch and bus voltage mismatch between the microgrid and the main grid or substation prior to re-synchronization;
determining an amount of power adjustment needed to reduce the bus angle or frequency mismatch and bus voltage mismatch to below respective predetermined thresholds;
determining at least one participation factor for each of the buses, each participation factor indicating an amount of influence power injection by the corresponding bus has on the bus angle or frequency mismatch or on the voltage mismatch;
allocating the amount of power adjustment to the buses in proportion to the participation factors assigned to the buses; and
re-synchronizing the microgrid to the main grid or substation responsive to the bus angle or frequency mismatch and bus voltage mismatch satisfying the respective predetermined thresholds.

2. The method of claim 1 , wherein determining the amount of power adjustment needed to reduce the bus angle or frequency mismatch and bus voltage mismatch to below the respective predetermined thresholds comprises determining an amount of real power adjustment and an amount of reactive power adjustment needed to reduce the bus angle or frequency mismatch and bus voltage mismatch to below the respective predetermined thresholds.

3. The method of claim 2 , wherein determining at least one participation factor for each of the buses comprises:
determining a first participation factor for each of the buses which indicates an amount of influence real power injection by the respective buses has on the bus angle or frequency mismatch; and
determining a second participation factor for each of the buses which indicates an amount of influence reactive power injection by the respective buses has on the voltage mismatch.

4. The method of claim 3 , wherein allocating the amount of power adjustment to the buses in proportion to the participation factors assigned to the buses comprises:
allocating the amount of real power adjustment to the buses in proportion to the first participation factors assigned to the buses; and
allocating the amount of reactive power adjustment to the buses in proportion to the second participation factors assigned to the buses.

5. The method of claim 3 , wherein determining the first participation factor for each of the buses comprises:
performing a singular value decomposition of a matrix that relates the amount of real power adjustment to the bus angle or frequency mismatch so as to yield a diagonal matrix having singular values which relate change in real power to change in bus angle or frequency for the buses; and
determining the sensitivity of the largest singular value to variables associated with the buses.

6. The method of claim 5 , wherein the variables associated with the buses are the diagonal elements of the matrix that relates the amount of real power adjustment to the bus angle or frequency mismatch.

7. The method of claim 3 , wherein determining the second participation factor for each of the buses comprises:
performing a singular value decomposition of a matrix that relates the amount of reactive power adjustment to the bus angle or frequency mismatch so as to yield a diagonal matrix having singular values which relate change in reactive power to change in bus angle or frequency for the buses; and
determining the sensitivity of the largest singular value to variables associated with the buses.

8. The method of claim 7 , wherein the variables associated with the buses are the diagonal elements of the matrix that relates the amount of reactive power adjustment to the bus angle or frequency mismatch.

9. The method of claim 2 , further comprising:
preventing one or more of the buses from contributing to the real power adjustment; and
normalizing the participation factors so that the sum of the normalized participation factors for the buses allowed to contribute to the real power adjustment equals one.

10. The method of claim 2 , further comprising:
preventing one or more of the buses from contributing to the reactive power adjustment; and
normalizing the participation factors so that the sum of the normalized participation factors for the buses allowed to contribute to the reactive power adjustment equals one.

11. The method of claim 1 , wherein allocating the amount of power adjustment to the buses in proportion to the participation factors assigned to the buses comprises instructing the energy resources connected to the buses to adjust their operating set points in proportion to the participation factors assigned to the buses.

12. The method of claim 11 , further comprising:
excluding one or more of the resources from being considered in determining the participation factors for the buses, responsive to the one or more resources operating at or close to its maximum operating set point limit.

13. The method of claim 11 , further comprising:
shedding one or more of the loads so as to enter islanded mode in which the microgrid is disconnected from the main grid or substation, in accordance with the participation factors assigned to the buses.

14. A controller for a microgrid that includes a plurality of buses to which energy resources and loads are connected, the controller comprising a re-synchronization unit operable to:
determine a degree of bus angle or frequency mismatch and bus voltage mismatch between the microgrid and the main grid or substation prior to re-synchronization;
determine an amount of power adjustment needed to reduce the bus angle or frequency mismatch and bus voltage mismatch to below respective predetermined thresholds;
determine at least one participation factor for each of the buses, each participation factor indicating an amount of influence power injection by the corresponding bus has on the bus angle or frequency mismatch or on the voltage mismatch;
allocate the amount of power adjustment to the buses in proportion to the participation factors assigned to the buses; and
re-synchronize the microgrid to the main grid or substation responsive to the bus angle or frequency mismatch and bus voltage mismatch satisfying the respective predetermined thresholds.

15. The controller of claim 14 , wherein the re-synchronization unit is operable to determine an amount of real power adjustment and an amount of reactive power adjustment needed to reduce the bus angle or frequency mismatch and bus voltage mismatch to below the respective predetermined thresholds.

16. The controller of claim 15 , wherein the re-synchronization unit is operable to determining a first participation factor for each of the buses which indicates an amount of influence real power injection by the respective buses has on the bus angle or frequency mismatch, and determine a second participation factor for each of the buses which indicates an amount of influence reactive power injection by the respective buses has on the voltage mismatch.

17. The controller of claim 16 , wherein the re-synchronization unit is operable to allocate the amount of real power adjustment to the buses in proportion to the first participation factors assigned to the buses, and allocate the amount of reactive power adjustment to the buses in proportion to the second participation factors assigned to the buses.

18. The controller of claim 16 , wherein the re-synchronizat

Assignees

• Abb Technology Ltd
• Abb Schweiz Ag

Inventors

• Singh Ravindra
• Ishchenko Dmitry

Classifications

• H02J2101/30

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• H02J2101/20

  Dispersed power generation using renewable energy sources · CPC title

• H02J13/333

  the equipment forming part of substations · CPC title