Method and system for power grid voltage regulation by distributed energy resources

Patent metadata

Field	Value
Publication number	US-10910841-B2
Application number	US-201515747588-A
Country	US
Kind code	B2
Filing date	Nov 10, 2015
Priority date	Nov 10, 2015
Publication date	Feb 2, 2021
Grant date	Feb 2, 2021

Abstract

A system and method for regulating a voltage at a point of common coupling (35) (PCC) of a distributed energy resource farm (1) connected to an electrical power grid (37). The distributed energy resource farm includes a plurality of connected distributed energy resources (2, 3) each supplying a terminal voltage. The system includes a component (50) for measuring a PCC voltage at the PCC, and another component (39, 41) for determining a first value based on a relationship between a scheduled voltage at the PCC and the measured PCC voltage relative to a dead band voltage region (66). A further component (39, 41) regulates the voltage at the point of common coupling by controlling the terminal voltage of each one of the plurality of distributed energy resources in response to the relationship between the scheduled voltage and the measured voltage at the PCC.

First claim

The invention claimed is:

1. A method for controlling distributed energy resources supplying electrical power to a power system through a point of common coupling, the method comprising:
controlling an output voltage of at least one of the distributed energy resources to vary inversely with a power system voltage measured at the point of common coupling without consideration of reactive power; and
controlling the output voltage of the at least one of the distributed energy resources in accordance with an established relationship between the voltage measured at the point of common coupling and the controlled output voltage;
wherein the relationship comprises a low voltage region and a high voltage region separated by a dead band region; and wherein the relationship is an inverse relationship in the high voltage region and in the low voltage region, but the controlled output voltage does not vary with a varying voltage measured at the point of common coupling in the dead band region.

2. The method of claim 1 , wherein the inverse relationships in the low voltage and high voltage regions are linear.

3. The method of claim 1 , further comprising:
controlling the output voltage of the at least one of the distributed energy resources in accordance with an established relationship between the voltage measured at the point of common coupling and the controlled output voltage; and wherein the relationship is not symmetrical between a high voltage region and a low voltage region of the relationship.

4. The method of claim 3 , further comprising:
the relationship comprising a more robust response in the low voltage region than in the high voltage region.

5. The method of claim 1 , further comprising:
controlling the output voltage of at least two of the distributed energy resources in accordance with a respective relationship between the voltage measured at the point of common coupling and a respective controlled output voltage for the respective distributed energy resource, wherein the relationship is different for the at least two distributed energy resources.

6. The method of claim 1 , further comprising:
establishing a relationship between the voltage measured at the point of common coupling and the controlled output voltage; and
controlling the output voltage of the at least one of the distributed energy resources in accordance with the relationship; wherein the relationship is at least one of the group of linear, stepped, table based, schedule based, and embodied in a mathematical relationship.

7. A system for regulating a voltage at a point of common coupling connected to an electrical power grid, wherein a distributed energy resource farm supplies the voltage to the point of common coupling, the distributed energy resource farm comprising a plurality of connected distributed energy resources each supplying a terminal voltage, the system comprising:
a voltage determining device providing an output responsive to a power system PCC voltage at the point of common coupling; and
a control device operatively connected to the voltage determining device and controlling a terminal voltage of an associated distributed energy resource in the farm to vary inversely responsive to the PCC voltage without consideration of reactive power;
wherein the control device is adapted to control the distributed energy resources according to the method of claim 1 .

8. The system of claim 7 ,
wherein the control device comprises a table of terminal voltages indexed to the PCC voltage; or
wherein the control device comprises an equation relating the PCC voltage and the terminal voltage.

9. The system of claim 7 , wherein the control device comprises a relationship between PCC voltage and terminal voltage, the relationship comprising a low voltage region and a high voltage region.

10. The system of claim 9 , wherein the high voltage region and the low voltage region are separated by a dead band region within which a value of terminal voltage does not vary with a varying PCC voltage.

11. The system of claim 9 ,
wherein the relationship is linear in at least one of the high voltage region and the low voltage region; or
wherein the relationship is not symmetric between the high voltage region and the low voltage region; or
wherein the relationship is more robust in the low voltage region than in the high voltage region.

12. The system of claim 7 , further comprising:
each of at least two of the distributed energy resources being controlled responsive to the PCC voltage without consideration of reactive power in accordance with a respective relationship between the PCC voltage and a respective terminal voltage for the respective distributed energy resource, wherein the relationship is different for the at least two of the distributed energy resources.

13. A system for regulating a voltage at a point of common coupling connected to an electrical power grid, wherein a distributed energy resource farm supplies the voltage to the point of common coupling, the distributed energy resource farm comprising a plurality of connected distributed energy resources each supplying a terminal voltage, the system comprising:
a potential transformer connected at the point of common coupling and providing a PCC voltage output;
a controller receiving the PCC voltage output and providing a terminal voltage control signal responsive to a predetermined inverse relationship between PCC voltage output and the terminal voltage over a first range of PCC voltage outputs and no variation in the terminal voltage over a second range of PCC voltage outputs, without consideration of reactive power; and
a converter controlling a terminal voltage of at least one of the distributed energy resources responsive to the terminal voltage control signal.

14. The system of claim 13 , wherein:
the first range of PCC voltage outputs comprises a low voltage region and a high voltage region and the second range of PCC voltage outputs comprises a dead band region between the low voltage region and the high voltage region.

15. The system of claim 14 , wherein the high voltage region and the low voltage region are not symmetrical about the dead band region.

16. The system of claim 14 , wherein the PCC voltage and terminal voltage vary inversely in both the high voltage region and the low voltage region.

Assignees

• Siemens Gamesa Renewable Energy As

Inventors

• Nelson Robert J
• Yazghi Najlae

Classifications

• H02J2101/28

  Wind energy · CPC title

• G05F1/44 Primary

  semiconductor devices only · CPC title

• H02J3/381

  Dispersed generators · CPC title

• Y02E10/76

  Power conversion electric or electronic aspects · CPC title

• H02J3/18

  Arrangements for adjusting, eliminating or compensating reactive power in networks · CPC title