Method for operating an energy supply system, device for exchanging electrical power in an energy supply system, and energy supply system

Patent metadata

Field	Value
Publication number	US-12438364-B2
Application number	US-202318389971-A
Country	US
Kind code	B2
Filing date	Dec 20, 2023
Priority date	Jun 24, 2021
Publication date	Oct 7, 2025
Grant date	Oct 7, 2025

Abstract

The disclosure relates to a method for operating an energy supply system, wherein a first and a second DC unit exchange power with an AC bus using a first and a second power converter. With transmission using a transformer, this power is combined and converted using a third power converter into a DC grid power of a DC grid and/or vice versa.

First claim

What is claimed is:

1. A method for operating an energy supply system having at least one energy generation unit, comprising:
exchanging power between a first DC unit and an AC bus using a first power converter, wherein a first DC power of the first DC unit is converted into a first AC power using the first power converter and vice versa,
exchanging power between a second DC unit and the AC bus using a second power converter, wherein a second DC power of the second DC unit is converted into a second AC power using the second power converter and vice versa,
combining the first AC power and the second AC power into an AC bus power of the AC bus,
transmitting the AC bus power using a transformer,
exchanging power between the AC bus and a DC grid using a third power converter, wherein the AC bus power transmitted by the transformer is converted using the third power converter into a DC grid power and vice versa,
wherein at least the first DC unit comprises an energy generation unit comprising at least one PV generator,
wherein a frequency and an amplitude of an AC voltage or of an AC current on the AC bus are set, wherein the third power converter sets the frequency on the AC bus as a function of the DC grid power and, for setting the AC voltage or the AC current, sets the DC grid power as a function of the AC bus power.

2. The method according to claim 1 , wherein the first power converter operates the first DC unit at an operating point of maximum power and converts the first DC power into a first AC current and feeds it into the AC bus, wherein the first AC current follows the AC voltage in the AC bus.

3. The method according to claim 1 , wherein the second DC power is generated, stored or consumed by the second DC unit, wherein the second DC power is converted by the second power converter into a second AC current and fed into the AC bus, wherein the second AC current follows the AC voltage in the AC bus.

4. The method according to claim 1 , wherein the DC grid power is generated, stored or consumed by DC grid users connected to the DC grid.

5. The method according to claim 1 , further comprising: exchanging power between the AC bus and a further DC unit using a further power converter, wherein a further DC power of the further DC unit is converted into a further AC power using the further power converter and vice versa.

6. The method according to claim 5 , wherein the further DC power is generated, stored or consumed by the further DC unit.

7. The method according to claim 1 , wherein the frequency on the AC bus is set by the third power converter using an f(P) characteristic as a function of the DC grid power.

8. The method according to claim 1 , wherein the first and second DC power of the first and second DC units, respectively, is set by the respective power converter using a P(f) characteristic as a function of the frequency on the AC bus.

9. A device for exchanging electrical power in an energy supply system having at least one energy generation unit, comprising:
an AC bus to which a first power converter and a second power converter are connected,
wherein the first power converter is configured to convert a first DC power of a first DC unit into first AC power and vice versa, and wherein the second power converter is configured to convert a second DC power of a second DC unit into second AC power and vice versa, and
wherein the first and second power converter are each connected on an AC side to the AC bus so that the first and second AC power are transmittable as AC bus power via the AC bus,
wherein the device has a transformer arranged between the AC bus and an AC side of a third power converter,
wherein the transformer is configured to transmit the AC bus power and to provide galvanic isolation,
wherein the third power converter is configured to convert the transmitted AC bus power into DC grid power and vice versa, and
wherein, on a DC side of the third power converter, a DC grid is connected in which DC grid users are operated with the DC grid power,
wherein at least the first DC unit comprises an energy generation unit having at least one PV generator,
wherein the third power converter is configured to set a frequency and an amplitude of an AC voltage or an AC current on the AC bus,
wherein a control circuit of the third power converter sets the frequency on the AC bus as a function of the DC grid power and sets the DC grid power as a function of the AC bus power.

10. The device according to claim 9 , wherein the first power converter is configured to operate the first DC unit at an operating point of maximum power and to convert the first DC power into a first AC current and to feed it into the AC bus, wherein the first AC current follows the AC voltage in the AC bus.

11. The device according to claim 9 , wherein a further DC unit is connected to the AC bus via a further power converter, wherein the further power converter is configured to convert a further DC power of the further DC unit into a further AC power and vice versa.

12. The device according to claim 11 , wherein the second and the further DC unit are configured to generate, store or consume the respective DC power.

13. The device according to claim 9 , wherein the transformer is grounded on its side connected to the AC bus.

14. The device according to claim 9 , wherein the control circuit is at least partially implemented by the first, the second or the third power converter.

15. The device according to claim 9 , wherein the controller is at least partially implemented outside the device.

16. An energy supply system comprising a device according to claim 9 , having:
a first DC unit which is formed as a first PV system having at least one PV generator,
a second DC unit which is formed as a second PV system having at least one PV generator or formed as an energy store, and
a DC grid to which DC grid users are connected for drawing DC grid power and a superordinate AC supply grid for supplying the DC grid.

17. The energy supply system according to claim 16 , having the controller, which is configured to receive a setpoint for the DC grid power and to operate the first power converter, the second power converter or the third power converter such that the DC grid power corresponds to the setpoint.

Assignees

• Sma Solar Technology Ag

Inventors

• Kratochvil Marcel
• Unru Alexander

Classifications

• H02J2101/25

  involving maximum power point tracking control for photovoltaic sources · CPC title

• H02J4/25 Primary

  for transfer of electric power between AC and DC networks, e.g. for supplying the DC section within a load from an AC mains system · CPC title

• H02J2101/40

  Hybrid power plants, i.e. a plurality of different generation technologies being operated at one power plant · CPC title

• H02J2101/22

  Solar energy · CPC title

• Y02E10/56

  Power conversion systems, e.g. maximum power point trackers · CPC title