US-12620813-B2 - Inverter and control method for inverter

Abstract

An inverter and a control method for the inverter. The inverter includes a direct current conversion circuit, a direct current bus, an inverter circuit, and a controller. An input end of the direct current conversion circuit is connected to an input end of the inverter, an output end of the direct current conversion circuit is connected to an input end of the inverter circuit through the direct current bus, and an output end of the inverter circuit is connected to an output end of the inverter. The controller obtains a reactive voltage control amount based on actual output active power and reference output active power of the inverter circuit and adjusts an output voltage of the inverter circuit based on the reactive voltage control amount and a reference output voltage.

Inventors

• Fei Xu
• Xinyu Yu
• Mingquan ZHAO
• Zisen QU
• Kai Xin

Assignees

• Huawei Digital Power Technologies Co., Ltd.

Dates

Publication Date

20260505

Application Date

20231129

Priority Date

20221130

Claims (20)

1. 1 . An inverter system comprising: a direct current conversion circuit; a direct current bus; an inverter circuit; and a controller, wherein an input end of the direct current conversion circuit is connected to an input end of the inverter system, an output end of the direct current conversion circuit is connected to an input end of the inverter circuit through the direct current bus, and an output end of the inverter circuit is connected to an output end of the inverter system; and the controller is configured to: obtain a reactive voltage control amount based on actual output active power and reference output active power of the inverter circuit, and adjust an output voltage of the inverter circuit based on the reactive voltage control amount and a reference output voltage, to adjust the actual output active power of the inverter circuit based on a sign of a q-axis output voltage variation, wherein the reactive voltage control amount is the q-axis output voltage variation or an output voltage frequency variation, the q-axis output voltage variation corresponding to the output voltage frequency variation.
2. 2 . The inverter system according to claim 1 , wherein the controller is further configured to: obtain an actual bus voltage of the direct current bus when the direct current conversion circuit is in a maximum power point tracking working state, and obtain the reference output active power of the inverter circuit based on the actual bus voltage and a reference bus voltage.
3. 3 . The inverter system according to claim 1 , wherein the controller is further configured to: when the inverter system receives a power scheduling instruction, determine first power carried in the power scheduling instruction as the reference output active power of the inverter circuit.
4. 4 . The inverter system according to claim 1 , wherein the controller is further configured to: when the q-axis output voltage variation is greater than 0, adjust the output voltage of the inverter circuit based on the q-axis output voltage variation and the reference output voltage, to increase the actual output active power of the inverter circuit.
5. 5 . The inverter system according to claim 4 , wherein the reference output voltage comprises a q-axis reference output voltage component, a d-axis reference output voltage component, and an output voltage reference frequency; and the controller is further configured to: obtain a q-axis target output voltage component based on the q-axis reference output voltage component and the q-axis output voltage variation, and adjust the output voltage of the inverter circuit based on the q-axis target output voltage component, the output voltage reference frequency, and the d-axis reference output voltage component.
6. 6 . The inverter system according to claim 1 , wherein the controller is further configured to: when the q-axis output voltage variation is less than 0, adjust the output voltage of the inverter circuit based on the q-axis output voltage variation and the reference output voltage, to decrease the actual output active power of the inverter circuit.
7. 7 . The inverter system according to claim 1 , wherein the reactive voltage control amount is an output voltage frequency variation; and the controller is further configured to: when the q-axis output voltage variation corresponding to the output voltage frequency variation is greater than 0, adjust the output voltage of the inverter circuit based on the output voltage frequency variation and the reference output voltage, to decrease the actual output active power of the inverter circuit.
8. 8 . The inverter system according to claim 7 , wherein the reference output voltage comprises a q-axis reference output voltage component, a d-axis reference output voltage component, and an output voltage reference frequency; and the controller is further configured to: obtain an output voltage target frequency based on the output voltage reference frequency and the output voltage frequency variation, and adjust the output voltage of the inverter circuit based on the output voltage target frequency, the q-axis reference output voltage component, and the d-axis reference output voltage component.
9. 9 . The inverter system according to claim 1 , wherein the reactive voltage control amount is an output voltage frequency variation; and the controller is further configured to: when the q-axis output voltage variation corresponding to the output voltage frequency variation is less than 0, adjust the output voltage of the inverter circuit based on the output voltage frequency variation and the reference output voltage, to increase the actual output active power of the inverter circuit.
10. 10 . The inverter system according to claim 1 , wherein the controller controls such that an absolute value of a difference between the actual output active power of the inverter circuit and the reference output active power is less than a preset difference threshold.
11. 11 . A method for an inverter system, wherein the inverter system comprises a direct current conversion circuit, a direct current bus, and an inverter circuit, an input end of the direct current conversion circuit is connected to an input end of the inverter system, an output end of the direct current conversion circuit is connected to an input end of the inverter circuit through the direct current bus, and an output end of the inverter circuit is connected to an output end of the inverter system; and the method comprises: obtaining a reactive voltage control amount based on actual output active power and reference output active power of the inverter circuit; and adjusting an output voltage of the inverter circuit based on the reactive voltage control amount and a reference output voltage, to adjust the actual output active power of the inverter circuit based on a sign of a q-axis output voltage variation, wherein the reactive voltage control amount is the q-axis output voltage variation or an output voltage frequency variation, the q-axis output voltage variation corresponding to the output voltage frequency variation.
12. 12 . The method according to claim 11 , further comprising: obtaining an actual bus voltage of the direct current bus when the direct current conversion circuit is in a maximum power point tracking working state; and obtaining the reference output active power of the inverter circuit based on the actual bus voltage and a reference bus voltage.
13. 13 . The method according to claim 11 , further comprising: when the inverter system receives a power scheduling instruction, determining a first power carried in the power scheduling instruction as the reference output active power of the inverter circuit.
14. 14 . The method according to claim 11 , wherein adjusting the output voltage of the inverter circuit based on the reactive voltage control amount and the reference output voltage further comprises: when the q-axis output voltage variation is greater than 0, adjusting the output voltage of the inverter circuit based on the q-axis output voltage variation and the reference output voltage, to increase the actual output active power of the inverter circuit.
15. 15 . The method according to claim 11 , wherein adjusting the output voltage of the inverter circuit based on the reactive voltage control amount and the reference output voltage further comprises: when the q-axis output voltage variation is less than 0, adjusting the output voltage of the inverter circuit based on the q-axis output voltage variation and the reference output voltage, to decrease the actual output active power of the inverter circuit.
16. 16 . The method according to claim 11 , wherein the reference output voltage comprises a q-axis reference output voltage component, a d-axis reference output voltage component, and an output voltage reference frequency; and adjusting the output voltage of the inverter circuit based on the q-axis output voltage variation and the reference output voltage further comprises: obtaining a q-axis target output voltage component based on the q-axis reference output voltage component and the q-axis output voltage variation, and adjusting the output voltage of the inverter circuit based on the q-axis target output voltage component, the d-axis reference output voltage component, and the output voltage reference frequency.
17. 17 . The method according to claim 11 , wherein the reactive voltage control amount is an output voltage frequency variation; and adjusting the output voltage of the inverter circuit based on the reactive voltage control amount and the reference output voltage further comprises: when the q-axis output voltage variation corresponding to the output voltage frequency variation is greater than 0, adjusting the output voltage of the inverter circuit based on the output voltage frequency variation and the reference output voltage, to decrease the actual output active power of the inverter circuit.
18. 18 . The method according to claim 17 , wherein the reference output voltage comprises a q-axis reference output voltage component, a d-axis reference output voltage component, and an output voltage reference frequency; and adjusting the output voltage of the inverter circuit based on the output voltage frequency variation and the reference output voltage further comprises: obtaining an output voltage target frequency based on the output voltage reference frequency and the output voltage frequency variation, and adjusting the output voltage of the inverter circuit based on the output voltage target frequency, the q-axis reference output voltage component, and the d-axis reference output voltage component.
19. 19 . The method according to claim 11 , wherein the reactive voltage control amount is an output voltage frequency variation; and adjusting the output voltage of the inverter circuit based on the reactive voltage control amount and the reference output voltage further comprises: when the q-axis output voltage variation corresponding to the output voltage frequency variation is less than 0, adjusting the output voltage of the inverter circuit based on the output voltage frequency variation and the reference output voltage, to increase the actual output active power of the inverter circuit.
20. 20 . The method according to claim 11 , further comprising controlling the inverter system such that an absolute value of a difference between the actual output active power of the inverter circuit and the reference output active power is less than a preset difference threshold.

Description

CROSS-REFERENCE TO RELATED DISCLOSURES This application claims priority to Chinese Patent Application No. 202211518092.3, filed on Nov. 30, 2022, which is hereby incorporated by reference in its entirety. TECHNICAL FIELD The embodiments relate to the field of power supply technologies, an inverter, and a control method for the inverter. BACKGROUND As a penetration rate of new energy power generation gradually increases, a photovoltaic grid-connected inverter is increasingly required to actively provide voltage and frequency support for a power grid. Currently, the photovoltaic grid-connected inverter may use a network construction control manner based on a virtual synchronous generator. The network construction control manner based on the virtual synchronous generator can actively provide support for the power grid. However, in the network construction control manner based on the conventional virtual synchronous generator, a control speed of output active power of the photovoltaic grid-connected inverter is slow. This limits an application scenario and scope of the photovoltaic grid-connected inverter. Therefore, it is particularly important to implement quick control on the output active power of the photovoltaic grid-connected inverter. SUMMARY The embodiments provide an inverter and a control method for the inverter, to quickly control actual output active power of the inverter when the inverter operates in a network construction control manner. According to a first aspect, the embodiments provide an inverter, and the inverter includes a direct current conversion circuit, a direct current bus, an inverter circuit, and a controller. An input end of the direct current conversion circuit is connected to an input end of the inverter, an output end of the direct current conversion circuit is connected to an input end of the inverter circuit through the direct current bus, and an output end of the inverter circuit is connected to an output end of the inverter. The controller obtains a reactive voltage control amount based on actual output active power and reference output active power of the inverter circuit and adjusts an output voltage of the inverter circuit based on the reactive voltage control amount and a reference output voltage, to quickly control actual output active power of the inverter when the inverter operates in a network construction control manner. With reference to the first aspect, in a first possible implementation, the controller further obtains an actual bus voltage of the direct current bus when the direct current conversion circuit is in a maximum power point tracking working state and obtains the reference output active power of the inverter circuit based on the actual bus voltage and a reference bus voltage. It may be understood that, because the inverter operates in the network construction control manner, it may be understood that the inverter operates in a voltage source mode. When operating in the voltage source mode, the inverter can track a maximum power point of a photovoltaic string. Therefore, the inverter not only provides voltage and frequency support for an alternating current power grid without a delay, but also effectively provides an energy yield of the inverter. With reference to the first aspect, in a second possible implementation, when the inverter receives a power scheduling instruction, the controller further determines first power carried in the power scheduling instruction as the reference output active power of the inverter circuit. It may be understood that, while operating in the voltage source mode, the inverter may further implement a fast power scheduling response. Therefore, the inverter not only can provide support and frequency support for the alternating current power grid without a delay, but also can quickly stabilize output power of a photovoltaic module at a non-maximum power point. In this way, output power of the inverter is stable. With reference to any one of the first aspect to the second possible implementation of the first aspect, in a third possible implementation, the reactive voltage control amount is a q-axis output voltage variation. When the q-axis output voltage variation is greater than 0, the controller adjusts the output voltage of the inverter circuit based on the q-axis output voltage variation and the reference output voltage, to increase the actual output active power of the inverter circuit. It may be understood that the inverter controls the output voltage of the inverter circuit in a manner of superimposing the q-axis output voltage variation that is greater than 0 on the q-axis reference output voltage in the reference output voltage, to quickly increase the actual output active power of the inverter circuit, and provide voltage and frequency support for the alternating current power grid without a delay. With reference to any one of the first aspect to the second possible implementation of the first aspect, in a fourth pos