Method and apparatus for the operation of a power station of fluctuating performance connected, besides a system former and at least one load, to a limited AC system

Patent metadata

Field	Value
Publication number	US-10186867-B2
Application number	US-201715459090-A
Country	US
Kind code	B2
Filing date	Mar 15, 2017
Priority date	Sep 15, 2014
Publication date	Jan 22, 2019
Grant date	Jan 22, 2019

Abstract

A method and associated apparatus for operating a power station of fluctuating electrical capacity that, besides a voltage-setting system former outputting active power and reactive power and at least one load, is connected to a limited AC grid. The method and associated apparatus includes defining a desired self-contained operating range of the system former on the PQ level, in which operating range the system former is able to efficiently correct fluctuations arising in a mains voltage of the AC grid, ascertaining a present operating point of the system former on the PQ level, and controlling an output of active power and reactive power by the power station such that the operating point of the system former is kept in the desired operating range.

First claim

The invention claimed is:

1. A method for operating a power station of fluctuating electrical capacity that, besides a voltage-setting system former outputting active power and reactive power and at least one load, is connected to a limited AC grid, comprising:
defining a desired self-contained operating range of the system former on the PQ level, in which operating range the system former is able to efficiently correct fluctuations arising in a mains voltage of the AC grid,
ascertaining a present operating point of the system former on the PQ level, and
controlling an output of active power and reactive power by the power station such that the operating point of the system former is kept in the desired operating range.

2. The method as claimed in claim 1 , further comprising maximizing a supply of active power by the power station while the operating point of the system former remains in the desired operating range.

3. The method as claimed in claim 1 , wherein the system former comprises a hydroelectric generator or a combustion generator or a battery inverter.

4. The method as claimed in claim 3 , further comprising:
increasing the supply of power by the power station when the ascertained reserve power (P Res ) exceeds a maximum reserve power (P Res,max ), until the at least one or the still further power source is deactivated by the power source controller; and
maximizing the supply of power by the power controller when the ascertained reserve power (P Res ) is in the range between the minimum reserve power (P Res,min ) and the maximum reserve power (P Res,max ), only for as long as no further power source is deactivated by the power source controller.

5. The method as claimed in claim 4 , wherein a present power consumption (Pin) of all loads in the AC grid is detected directly or as a present power output

(

∑
j

⁢

Pout
Baj

+

Pout
PV

+

Pout
NB

)

of all power sources.

6. The method as claimed in claim 5 , wherein the minimum reserve power (P Res,min ) or the maximum reserve power (P Res,max ), or both are computed using a percentage of the present power consumptions (Pin) of all loads as a summand.

7. The method as claimed in claim 1 , further comprising activating or deactivating at least one further power source connected to the limited AC grid as required in order to keep the operating point of the system former in the desired operating range.

8. The method as claimed in claim 7 , wherein the at least one further power source comprises a combustion generator.

9. The method as claimed in claim 7 , wherein the at least one further power source is activated and deactivated by a power source controller and the supply of active power by the power station is reduced until the at least one or another further power source is activated by the power source controller when the operating point of the system former leaves the desired operating range.

10. The method as claimed in claim 9 , wherein the supply of power by the power station is increased until the at least one or the still further power source is deactivated by the power source controller when the operating point of the system former leaves the desired operating range.

11. The method as claimed in claim 7 , further comprising ascertaining a reserve power (P Res ) currently available in the AC grid, wherein only activated power sources are taken into consideration, and when the ascertained reserve power (P Res ) drops below a minimum reserve power (P Res,min ), reducing the supply of power by the power station until the at least one or another further power source is activated by the power source controller.

12. The method as claimed in claim 11 , further comprising increasing the supply of power by the power station when the ascertained reserve power (P Res ) exceeds a maximum reserve power (P Res,max ), until the at least one or the still further power source is deactivated by the power source controller.

13. The method as claimed in claim 12 , further comprising computing the maximum reserve power (P Res,max ) as a sum of the minimum reserve power (P Res,min ) and the maximum capacity of the further power source (Pmax Baj ), which the generator controller ( 6 ) would deactivate first, times a stabilization factor (k) greater than 1.

14. The method as claimed in claim 11 , further comprising:
detecting a present power output (Pout PV ) and the present capacity (Pmax PV ) of the power station; and
stipulating currently available reserve power (P Res ) by taking into consideration a percentage of a difference between the present capacity (Pmax PV ) and the present power output (Pout PV ) of the power station.

15. The method as claimed in claim 14 , further comprising:
increasing the supply of power by the power station when the ascertained reserve power (P Res ) exceeds a maximum reserve power (P Res,max ), until the at least one or the still further power source is deactivated by the power source controller; and
computing the minimum reserve power (P Res,min ) or the maximum reserve power (P Res,max ), or both using a percentage of the present power output (Pout PV ) of the power station as a summand.

16. The method as claimed in claim 1 , further comprising detecting a present power output (Pout PV ) and the present capacity (Pmax PV ) of the power station.

17. The method as claimed in claim 1 , further comprising preventing a longer-term drop below a minimum power output (Pmin) and any drop below a power output of zero for all power sources by reducing the supply of power by the power station.

18. A control apparatus for controlling a power station that, besides at least one voltage-setting system former outputting active power and reactive power and at least one load, is connectable to a limited AC grid, wherein the control apparatus is configured to:
define a desired self-contained operating range of the system former on the PQ level, in which operating range the system former is able to efficiently correct fluctuations arising in a mains voltage of the AC grid,
ascertain a present operating point of the system former on the PQ level, and
control an output of active power and reactive power by the power station such that the operating point of the system former is kept in the desired operating range.

19. A control apparatus for controlling a power station that, besides at least one voltage-setting system former outputting active power and reactive power, at least one further power source and at least one load, is connectable to a limited AC grid, wherein the at least one further resource outputting power is activated or deactivated as required, wherein the control apparatus is configured to:
define a desired self-contained operating range of the system former on the PQ level, in which operating range the system former is able to efficiently correct fluctuations arising in a mains voltage of the AC grid,
ascertain a present operating point of the system former on the PQ level,
control an output of active power and

Assignees

• Sma Solar Technology Ag

Inventors

• Premm Daniel
• Mende Denis
• Schuetz Christian

Classifications

• H02J3/381

  Dispersed generators · CPC title

• H02J3/48 Primary

  Controlling the sharing of active power · CPC title

• Y04S10/30

  State monitoring, e.g. fault, temperature monitoring, insulator monitoring, corona discharge · CPC title

• H02M7/44

  by static converters · CPC title

• H02J3/50

  Controlling the sharing of reactive power · CPC title