Photovoltaic inverter and control method thereof, and photovoltaic system

Patent metadata

Field	Value
Publication number	US-2024380212-A1
Application number	US-202418619287-A
Country	US
Kind code	A1
Filing date	Mar 28, 2024
Priority date	May 11, 2023
Publication date	Nov 14, 2024
Grant date	—

Abstract

A photovoltaic inverter and a control method thereof, and a photovoltaic system. The photovoltaic inverter system includes a voltage conversion circuit, an inverter circuit, and a controller. The controller is configured to increase, based on an output power of the inverter circuit in a current time period and an output power of the inverter circuit in a first time period, an output power of the inverter circuit when the voltage conversion circuit does not work in a maximum power state. An increase of the output power of the inverter circuit is an estimated power increment value of the inverter circuit so as to stably increase an output power of the inverter while ensuring stable operation of the inverter and safe use of a power component, and improve power supply efficiency of the photovoltaic system.

First claim

What is claimed is:

1 . A photovoltaic inverter, comprising:
a voltage conversion circuit, an inverter circuit, and a controller, one end of the voltage conversion circuit is configured to connect to a photovoltaic module, the other end of the voltage conversion circuit is configured to connect to one end of the inverter circuit, the other end of the inverter circuit is configured to connect to a power grid, and the inverter circuit and the power grid are connected to a grid-connected point; the voltage conversion circuit is configured to output, to the inverter circuit, a direct current input by the photovoltaic module; the inverter circuit is configured to receive the direct current output by the voltage conversion circuit, convert the received direct current output by the voltage conversion circuit into an alternating current, and output the alternating current to the power grid; and the controller is configured to increase, based on an output power of the inverter circuit in a current time period and an output power of the inverter circuit in a first time period, an output power of the inverter circuit when the voltage conversion circuit does not work in a maximum power state, wherein an increase in the output power of the inverter circuit is an estimated power increment value of the inverter circuit, the estimated power increment value of the inverter circuit is in direct proportion to a difference between the output power in the current time period and the output power in the first time period, and the first time period is before the current time period.

2 . The photovoltaic inverter according to claim 1 , wherein the other end of the voltage conversion circuit is configured to connect to an energy storage unit, and is configured to output, to the energy storage unit, the direct current input by the photovoltaic module; and
the inverter circuit is further configured to receive the direct current output by the energy storage unit, and is configured to: convert the received direct current output by the energy storage unit into an alternating current, and output the alternating current to the power grid.

3 . The photovoltaic inverter according to claim 1 , wherein the controller is further configured to:
when the voltage conversion circuit does not work in the maximum power state, if the difference between the output power of the inverter circuit in the current time period and the output power of the inverter circuit in the first time period is less than a first threshold, set the estimated power increment value of the inverter circuit to a first power increment value.

4 . The photovoltaic inverter according to claim 3 , wherein the controller is further configured to:
when the voltage conversion circuit does not work in the maximum power state, if the difference between the output power of the inverter circuit in the current time period and the output power of the inverter circuit in the first time period is greater than or equal to the first threshold, and a difference between the output power of the inverter circuit in the current time period and an output power of the inverter circuit in a second time period is less than a second threshold, set the estimated power increment value of the inverter circuit to a second power increment value, wherein the second time period is before the first time period, and the second power increment value is greater than the first power increment value.

5 . The photovoltaic inverter according to claim 4 , wherein the controller is further configured to:
when the voltage conversion circuit does not work in the maximum power state, if the difference between the output power of the inverter circuit in the current time period and the output power of the inverter circuit in the first time period is greater than or equal to the first threshold, and the difference between the output power of the inverter circuit in the current time period and the output power of the inverter circuit in the second time period is greater than or equal to the second threshold, set the estimated power increment value of the inverter circuit to a third power increment value, wherein the third power increment value is greater than the second power increment value.

6 . The photovoltaic inverter according to claim 4 , wherein the controller is configured to set the estimated power increment value of the inverter circuit to a fourth power increment value when the voltage conversion circuit switches from the maximum power state to a non-maximum power state, wherein the fourth power increment value is less than the second power increment value.

7 . A photovoltaic system, comprising:
one or more photovoltaic inverters, wherein each of the photovoltaic inverter comprises a voltage conversion circuit, an inverter circuit, and a controller, one end of the voltage conversion circuit is configured to connect to a photovoltaic module, the other end of the voltage conversion circuit is configured to connect to one end of the inverter circuit, the other end of the inverter circuit is configured to connect to a power grid, and the inverter circuit and the power grid are connected to a grid-connected point; the voltage conversion circuit is configured to output, to the inverter circuit, a direct current input by the photovoltaic module; the inverter circuit is configured to receive the direct current output by the voltage conversion circuit, convert the received direct current output by the voltage conversion circuit into an alternating current, and output the alternating current to the power grid; and the controller is configured to increase, based on an output power of the inverter circuit in a current time period and an output power of the inverter circuit in a first time period, an output power of the inverter circuit when the voltage conversion circuit does not work in a maximum power state, wherein an increase in the output power of the inverter circuit is an estimated power increment value of the inverter circuit, the estimated power increment value of the inverter circuit is in direct proportion to a difference between the output power in the current time period and the output power in the first time period, and the first time period is before the current time period.

8 . The photovoltaic inverter according to claim 7 , wherein the other end of the voltage conversion circuit is further configured to connect to an energy storage unit, and is configured to output, to the energy storage unit, the direct current input by the photovoltaic module; and
the inverter circuit is further configured to receive the direct current output by the energy storage unit, and is configured to: convert the received direct current output by the energy storage unit into an alternating current, and output the alternating current to the power grid.

9 . The photovoltaic inverter according to claim 7 , wherein the controller is further configured to:
when the voltage conversion circuit does not work in the maximum power state, if the difference between the output power of the inverter circuit in the current time period and the output power of the inverter circuit in the first time period is less than a first threshold, set the estimated power increment value of the inverter circuit to a first power increment value.

10 . The photovoltaic inverter according to claim 9 , wherein the controller is further configured to:
when the voltage conversion circuit does not work in the maximum power state, if the difference between the output power of the inverter circuit in the current time period and the output power of the inverter circuit in the first time period is greater than or equal to the first threshold, and a difference

Assignees

• Huawei Digital Power Tech Co Ltd

Inventors

• Xiao Gang
• Huang Chongyue
• Gu Guilei
• Song Zhengang
• Liu Wentao
• Li Xuegong

Classifications

• H02J2101/25

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

• H02J2101/24

  Photovoltaics · CPC title

• H02J7/865

  Battery or charger load switching, e.g. concurrent charging and load supply (H02J7/50 takes precedence) · CPC title

• H02M7/483

  Converters with outputs that each can have more than two voltages levels · CPC title

• H02J3/28

  Arrangements for balancing of the load in networks by storage of energy · CPC title