CN-122017685-A - Fault determination method and device, three-phase power converter and power system

Abstract

The invention discloses a fault determining method, a device, a three-phase power converter and a power system, wherein the fault determining method comprises the steps of obtaining the terminal temperature of each alternating current wiring terminal of the three-phase power converter, determining the temperature difference value between two alternating current wiring terminals according to the terminal temperature of each alternating current wiring terminal, and determining whether the three-phase power converter meets a preset virtual connection fault condition according to the determined temperature difference value between the two alternating current wiring terminals, wherein the preset virtual connection fault condition comprises that the temperature difference value between any two alternating current wiring terminals is larger than a preset temperature difference threshold value. According to the method, whether the three-phase power converter has virtual connection faults or not can be identified in advance through the temperature difference value between the two-phase alternating-current wiring terminals of the three-phase power converter, so that the timeliness of fault identification is improved.

Inventors

• MA CHENCHENG
• LI BIJIE
• YU ZHENYANG

Assignees

• 阳光电源股份有限公司

Dates

Publication Date

20260512

Application Date

20251226

Claims (18)

1. 1. A fault determination method, comprising: acquiring the terminal temperature of each alternating current wiring terminal of the three-phase power converter; determining the temperature difference between the alternating current wiring terminals of each two phases according to the terminal temperature of the alternating current wiring terminals of each phase; and determining whether the three-phase power converter meets a preset virtual connection fault condition according to the determined temperature difference value between the alternating current wiring terminals of each two phases, wherein the preset virtual connection fault condition comprises that the temperature difference value between the alternating current wiring terminals of any two phases is larger than a preset temperature difference threshold value.
2. 2. The method of claim 1, wherein determining whether the three-phase power converter satisfies a virtual-connection fault condition based on the determined temperature difference between the ac terminals of each two phases comprises: determining the maximum value of the temperature difference according to the determined temperature difference between the alternating current wiring terminals of each two phases; And determining whether the three-phase power converter meets a virtual connection fault condition according to the maximum value of the temperature difference, wherein the preset virtual connection fault condition further comprises that the maximum value of the temperature difference is larger than the preset temperature difference threshold value.
3. 3. The method of claim 1, wherein determining whether the three-phase power converter satisfies a virtual-connection fault condition based on the determined temperature difference between the ac terminals of each two phases comprises: And determining whether the three-phase power converter meets a virtual connection fault condition according to the terminal temperature of each phase of alternating current wiring terminals and the determined temperature difference value between each two phases of alternating current wiring terminals, wherein the preset virtual connection fault condition further comprises that the terminal temperature of any phase of alternating current wiring terminals is larger than a preset temperature threshold value, and the temperature difference value between any two phases of alternating current wiring terminals is larger than the preset temperature difference threshold value.
4. 4. A method according to claim 3, wherein determining whether the three-phase power converter meets a virtual connection fault condition based on the terminal temperature of the ac terminals of each phase and the determined temperature difference between the ac terminals of each phase comprises: determining the maximum value of the terminal temperature according to the terminal temperature of the alternating current wiring terminal of each phase; And determining whether the three-phase power converter meets a virtual connection fault condition according to the maximum terminal temperature and the determined temperature difference between the alternating current wiring terminals of each two phases, wherein the preset virtual connection fault condition further comprises that the maximum terminal temperature is greater than the preset temperature threshold, and the temperature difference between the alternating current wiring terminals of any two phases is greater than the preset temperature difference threshold.
5. 5. A method according to claim 3, wherein determining whether the three-phase power converter meets a virtual connection fault condition based on the terminal temperature of the ac terminals of each phase and the determined temperature difference between the ac terminals of each phase comprises: determining the maximum value of the terminal temperature according to the terminal temperature of the alternating current wiring terminal of each phase; determining the maximum value of the temperature difference according to the determined temperature difference between the alternating current wiring terminals of each two phases; and determining whether the three-phase power converter meets a virtual connection fault condition according to the terminal temperature maximum value and the temperature difference maximum value, wherein the preset virtual connection fault condition further comprises that the terminal temperature maximum value is larger than the preset temperature threshold value, and the temperature difference maximum value is larger than the preset temperature difference threshold value.
6. 6. The method according to any one of claims 3-5, further comprising: And determining the preset temperature threshold according to the current running state of the three-phase power converter.
7. 7. The method of claim 5, wherein determining the preset temperature threshold based on the current operating state of the three-phase power converter comprises: determining a normal terminal temperature according to at least one of a present current and a present power of the three-phase power converter; and determining the preset temperature threshold according to the normal terminal temperature and a preset allowance.
8. 8. The method of claim 6, wherein determining a normal terminal temperature based on at least one of a present current and a present power of the three-phase power converter comprises: Determining the terminal temperature corresponding to the current of the three-phase power converter in a normal operation state as the normal terminal temperature, or Determining the terminal temperature corresponding to the current power of the three-phase power converter in a normal operation state as the normal terminal temperature, or Determining a first terminal temperature corresponding to the current of the three-phase power converter in a normal operation state and a second terminal temperature corresponding to the current of the three-phase power converter in a normal operation state, and determining the smaller value of the first terminal temperature and the second terminal temperature as the normal terminal temperature.
9. 9. The method according to claim 1, wherein the method further comprises: And sending out fault alarm information under the condition that the three-phase power converter meets virtual connection fault conditions.
10. 10. The method of claim 1, wherein the three-phase power converter includes a plurality of temperature sensing elements, each for sensing a temperature of a conductive layer of one phase of the ac terminals, wherein obtaining a terminal temperature of each phase of the ac terminals of the three-phase power converter includes: and determining the terminal temperature of each phase of alternating current wiring terminal based on the temperature sensing information of each temperature measuring element.
11. 11. The method of claim 10, wherein each of said temperature sensing elements is disposed on a conductive layer of a phase of said ac terminals.
12. 12. The method of claim 10, wherein each of the temperature sensing elements is disposed on an ac junction box of the three-phase power converter to sense an ambient temperature of a conductive layer of one phase of the ac junction terminals.
13. 13. The method of claim 10, wherein each of the temperature sensing elements is disposed on a surface of a circuit board and corresponds to a conductive layer of one phase of the ac terminals, and wherein at least one layer of the circuit board is populated with a conductive layer of at least one phase of the ac terminals.
14. 14. The method of claim 12, wherein the conductive layer is a copper-clad layer.
15. 15. A computer-readable storage medium, on which a computer program is stored which, when processed by a processor, performs the fault determination method as claimed in any one of claims 1-14.
16. 16. A three-phase power converter comprising a memory, a processor and a fault determination program stored on the memory and executable on the processor, the processor implementing the fault determination method according to any one of claims 1-14 when executing the fault determination program.
17. 17. A fault determination apparatus, comprising: the acquisition module is used for acquiring the terminal temperature of each alternating-current wiring terminal of the three-phase power converter; the first determining module is used for determining a temperature difference value between the alternating current wiring terminals of each two phases according to the terminal temperature of the alternating current wiring terminals of each phase; And the second determining module is used for determining whether the three-phase power converter meets a preset virtual connection fault condition according to the determined temperature difference value between the alternating current wiring terminals of each two phases, wherein the preset virtual connection fault condition comprises that the temperature difference value between any two phases of alternating current wiring terminals is larger than a preset temperature difference threshold value.
18. 18. An electric power system comprising a three-phase power converter according to claim 16 or a fault determining apparatus according to claim 17.

Description

Fault determination method and device, three-phase power converter and power system Technical Field The application relates to the technical field of photovoltaics, in particular to a fault determination method and device, a three-phase power converter and a power system. Background The photovoltaic inverter is used as a power generation core device, and is particularly important in electric safety, fire safety, equipment quality safety and the like. In order to ensure the electrical safety of the photovoltaic inverter, measures such as overload protection, short-circuit protection and over-temperature protection are adopted in the related art, and though the electrical safety can be ensured by the protective measures, for some faults without obvious electrical characteristics in early stages, the protective measures have hysteresis, for example, if the alternating-current side alternating-current wiring terminal has the problems of virtual connection, loosening or poor contact and the like, the overcurrent or overload protection cannot be triggered in the early stage of virtual connection, but the inverter is in a fault state, and if grid connection is carried out in the fault state, the safety risk is caused, so that the reliability of the photovoltaic system is affected. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, an object of the present invention is to provide a fault determining method, which can identify whether a virtual connection fault occurs in a three-phase power converter in advance through a temperature difference value between two phase ac connection terminals of the three-phase power converter, so as to improve timeliness of fault identification. A second object of the present invention is to propose a computer readable storage medium. A third object of the present invention is to provide a three-phase power converter. A fourth object of the present invention is to propose a fault determining device. A fifth object of the present invention is to propose a power system. To achieve the above objective, according to a first aspect of the present invention, a fault determining method is provided, which includes obtaining a terminal temperature of each ac terminal of a three-phase power converter, determining a temperature difference between two ac terminals according to the terminal temperature of each ac terminal, and determining whether the three-phase power converter meets a preset virtual connection fault condition according to the determined temperature difference between two ac terminals, wherein the preset virtual connection fault condition includes that the temperature difference between any two ac terminals is greater than a preset temperature difference threshold. According to the fault determining method, terminal temperature of each alternating current wiring terminal of the three-phase power converter is obtained, temperature difference values between two alternating current wiring terminals are determined according to the terminal temperature of each alternating current wiring terminal, whether the three-phase power converter meets preset virtual connection fault conditions or not is determined according to the determined temperature difference values between the two alternating current wiring terminals, wherein the preset virtual connection fault conditions comprise that the temperature difference value between any two alternating current wiring terminals is larger than a preset temperature difference threshold value. Therefore, whether the three-phase power converter has virtual connection faults or not can be recognized in advance through the temperature difference value between the two-phase alternating-current wiring terminals of the three-phase power converter, and the problem that the three-phase power converter has safety risks due to hysteresis in a detection mode in the related technology is solved, and the reliability of a photovoltaic system is further improved. According to one embodiment of the invention, whether the three-phase power converter meets the virtual connection fault condition is determined according to the determined temperature difference value between the two-phase alternating-current wiring terminals, the method comprises the steps of determining the maximum value of the temperature difference value according to the determined temperature difference value between the two-phase alternating-current wiring terminals, and determining whether the three-phase power converter meets the virtual connection fault condition according to the maximum value of the temperature difference value, wherein the preset virtual connection fault condition further comprises that the maximum value of the temperature difference value is larger than a preset temperature difference threshold value. According to one embodiment of the invention, whether the three-phase power convert