Power system

Patent metadata

Field	Value
Publication number	US-12074444-B2
Application number	US-202217694085-A
Country	US
Kind code	B2
Filing date	Mar 14, 2022
Priority date	Apr 16, 2020
Publication date	Aug 27, 2024
Grant date	Aug 27, 2024

Abstract

A power system is disclosed. Output terminals of a power supply or a DC-to-DC unit are cascaded to increase an output voltage, so as to reduce a current between the power supply or the DC-to-DC unit and the DC-to-AC unit, and resolve cost and loss problems of the cable from the power supply or the DC-to-DC unit to the DC-to-AC unit. In addition, according to the power system provided in the embodiments of this application, a quantity of cables from the power supply or the DC-to-DC unit to the DC-to-AC unit may be further reduced by cascading output terminals of the power supply or the DC-to-DC unit and cascading inputs of the DC-to-AC unit, thereby reducing system costs. In addition, in the power system provided in the embodiments of this application, cascaded input and isolated output of the DC-to-AC unit can reduce a specification of a power conversion device.

First claim

What is claimed is:

1. A power system comprising:
N power modules; and
M DC-to-AC units, wherein N is an integer greater than 1, and M is an integer greater than 1;
wherein, each power module is configured with a positive output terminal and a negative output terminal, and each DC-to-AC unit is configured with a positive input terminal, a negative input terminal, and an output terminal, wherein a communication signal is coupled to a direct current cable connected between the power module and the DC-to-AC unit and used to implement communication between the power module and the DC-to-AC unit;
a positive output terminal of a first power module is coupled to a positive input terminal of a first DC-to-AC unit;
a negative output terminal of an n th power module is coupled in series to a positive output terminal of an (n+1) th power module to form a first node, wherein n is an integer greater than 0 and less than N;
a negative output terminal of an N th power module is coupled to a negative input terminal of an M th DC-to-AC unit;
a negative input terminal of an m th DC-to-AC unit is coupled in series to a positive input terminal of an (m+1) th DC-to-AC unit to form a second node, wherein m is an integer greater than 0 and less than M;
at least one first node and at least one second node are coupled; and
output terminals of the DC-to-AC units are isolated from each other for output.

2. The power system according to claim 1 , wherein a power module is a photovoltaic array and/or an energy storage power supply and/or a wind power generation direct current source; and
the photovoltaic array is formed by performing series/parallel combination of photovoltaic panels, or is formed by connecting an output of a photovoltaic panel to an optimizer or a shutdown device, and then performing series/parallel combination.

3. The power system according to claim 2 , wherein the communication signal is used to control the optimizer or the shutdown device, so as to implement fast shutdown.

4. The power system according to claim 1 , wherein similar output terminals of at least two groups of power modules are first connected in parallel and then connected in series to form the first node;
similar input terminals of at least two groups of DC-to-AC units are first connected in parallel and then connected in series to form the second node; and
similar output terminals of the at least two groups of DC-to-AC units are connected in parallel for output, or isolated for output.

5. The power system according to claim 1 , further comprising at least one energy storage unit, wherein
the energy storage unit is coupled in parallel to at least two direct current cables connected between the power module and the DC-to-AC unit.

6. The power system according to claim 5 , wherein the energy storage unit is an energy storage device, or the energy storage unit comprises a direct current conversion unit and the energy storage device, and the energy storage device comprises a supercapacitor or a battery.

7. The power system according to claim 5 , wherein the communication signal is coupled to a direct current cable connected between the energy storage unit and the power module, and is used to implement communication between the energy storage unit and the power module, or, the communication signal is coupled to a direct current cable connected between the energy storage unit and the DC-to-AC unit, and is used to implement communication between the energy storage unit and the DC-to-AC unit.

8. A power system comprising:
a first power supply;
a second power supply;
a first-stage DC-to-AC unit; and
a second-stage DC-to-AC unit, wherein,
a positive output terminal of the first power supply is coupled to a positive input terminal of the first-stage DC-to-AC unit;
a negative output terminal of the first power supply is coupled to a positive output terminal of the second power supply to form a first node;
a negative output terminal of the second power supply is coupled to a negative input terminal of the second-stage DC-to-AC unit;
a negative input terminal of the first-stage DC-to-AC unit is coupled to a positive input terminal of the second-stage DC-to-AC unit to form a second node, wherein any two of the first power supply, the second power supply, the first-stage DC-to-AC unit, and the second-stage DC-to-AC unit communicate by using a communication signal coupled to a direct current cable; and
output terminals of the first-stage DC-to-AC unit and the second-stage DC-to-AC unit are isolated from each other for output.

9. The power system according to claim 8 , wherein the positive output terminal of the first power supply is coupled to the positive input terminal of the first-stage DC-to-AC unit by using a first conductor, the negative output terminal of the second power supply is coupled to the negative input terminal of the second-stage DC-to-AC unit by using a second conductor, and the first node is coupled to the second node by using a third conductor;
a current value on the third conductor is less than or equal to a current value on the first conductor; or
a current value on the third conductor is less than or equal to a current value on the second conductor.

10. The power system according to claim 9 , wherein
the first conductor, the second conductor, and the third conductor are direct current conductors;
the first conductor, the second conductor, and the third conductor form a distributed double bus, the first conductor and the second conductor form a positive bus, and the second conductor and the third conductor form a negative bus; and
the third conductor is a middle bus of the distributed double bus.

11. The power system according to claim 8 , wherein both the first node and the second node are coupled to ground.

12. The power system according to claim 11 , wherein when the first node is coupled to the second node, and when an output voltage and/or an output current and/or an output power of one of the first power supply and the second power supply is less than a preset value, the corresponding first power supply or the corresponding second power supply stops working; and
at least one of the first-stage DC-to-AC unit and the second-stage DC-to-AC unit works.

13. The power system according to claim 8 , further comprising a first equalization circuit unit, configured to balance input voltages and/or powers and/or currents of the first-stage DC-to-AC unit and the second-stage DC-to-AC unit, wherein
the first equalization circuit unit is configured with a first interface, a second interface, and a third interface;
the first interface is coupled to the second node;
the second interface is coupled to a positive input terminal of the first-stage DC-to-AC unit; and
the third interface is coupled to a negative input terminal of the second-stage DC-to-AC unit.

14. The power system according to claim 13 , further comprising a second equalization circuit unit, configured to balance input voltages and/or powers and/or currents of the first-stage DC-to-AC unit and the second-stage DC-to-AC unit, wherein
the second equalization circuit unit is configured with a fourth interface and a fifth interface;
the fourth interface is coupled to the second node; and
the fifth interface is coupled to a positive input terminal of the first-stage DC-to-AC unit or coupled to a negative input terminal of the second-stage DC-to-AC unit.

15. The power system according to claim 14 , further comprising a third equalization circuit unit, configured to balance output voltages and/or powers and/or currents of the first power supply and the se

Assignees

• Huawei Digital Power Tech Co Ltd

Inventors

• Zhang Yanzhong
• Gao Yongbing
• Wang Xun
• Huempfner Roland

Classifications

• H02J2101/24

  Photovoltaics · CPC title

• H02J2101/28

  Wind energy · CPC title

• H02M7/44

  by static converters · CPC title

• Y02E10/56

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

• H02J3/381 Primary

  Dispersed generators · CPC title