A method, apparatus, and system for relay fault detection of an inverter system

Abstract

The application relates to a relay fault detection method, device and system of an inverter system, wherein the method comprises the following steps: detecting a first voltage difference of voltages on two sides of a bypass relay unit, and judging whether the first voltage difference meets a first preset condition; if yes, closing a relay of the bypass relay unit, detecting a second voltage difference of voltages on two sides of the bypass relay unit, and judging whether the second voltage difference meets a second preset condition; if yes, detecting a third voltage difference of voltages on two sides of an off-grid relay unit, and judging whether the third voltage difference meets a third preset condition; if yes, closing a relay of an on-grid relay unit, detecting a fourth voltage difference of voltages on two sides of the off-grid relay unit, and judging whether the fourth voltage difference meets a fourth preset condition; and if yes, the inverter system enters an on-grid working mode. According to the application, the detection time of the relay fault detection of the inverter system is shortened.

Description

Technical Field

[0001] This application relates to the field of relay fault detection technology, and in particular to a relay fault detection method, apparatus and system for an inverter system. Background Technology

[0002] The grid-connected and off-grid inverter has two external ports: a grid-connected port and an off-grid port. The off-grid port can typically be connected to uninterruptible loads, diesel generators, charging piles, etc. It consists of an inverter module, a filter module, and a relay module.

[0003] To ensure effective grid disconnection in the event of relay failure, and to guarantee reliable grid disconnection during off-grid operation, fault detection of the relays in the inverter system is necessary at each startup and during switching between grid-connected and off-grid modes. Existing relay fault detection methods in inverter systems are complex and time-consuming.

[0004] There is currently no effective solution to the problem of long fault detection time for relays in inverter systems in existing technologies. Summary of the Invention

[0005] This embodiment provides a relay fault detection method, device, and system for inverter systems to solve the problem of long detection time for relay faults in inverter systems in the prior art.

[0006] Firstly, this embodiment provides a relay fault detection method for an inverter system, the inverter system including a grid-connected relay unit, an off-grid relay unit, and a bypass relay unit. The method includes a grid-connected operating mode detection process, which includes:

[0007] All relays are disconnected. In response to the input fault detection command, the first voltage difference between the voltages on both sides of the bypass relay unit is detected, and it is determined whether the first voltage difference meets the first preset condition.

[0008] If not, it is determined that the relay of the bypass relay unit has a sticking fault; if yes, the relay of the bypass relay unit is closed, the second voltage difference between the voltages on both sides of the bypass relay unit is detected, and it is determined whether the second voltage difference meets the second preset condition.

[0009] If not, it is determined that the relay of the bypass relay unit has a non-engaging fault; if so, the third voltage difference between the voltages on both sides of the off-grid relay unit is detected, and it is determined whether the third voltage difference meets the third preset condition.

[0010] If not, it is determined that the relay of the grid-connected relay unit or the relay of the off-grid relay unit has a sticking fault; if yes, the relay of the grid-connected relay unit is closed, the fourth voltage difference between the two sides of the off-grid relay unit is detected, and it is determined whether the fourth voltage difference meets the fourth preset condition.

[0011] If not, it is determined that the relay of the grid-connected relay unit has a non-engaging fault; if so, the inverter system enters the grid-connected working mode.

[0012] In some embodiments, if so, a third voltage difference between the voltages on both sides of the off-grid relay unit is detected, and it is determined whether the third voltage difference meets a third preset condition, including:

[0013] When the second voltage difference meets the second preset condition, at least one set of relays in the grid-connected relay unit is closed;

[0014] After closing at least one set of relays in the grid-connected relay unit, the third voltage difference between the two sides of the off-grid relay unit is detected, and it is determined whether the third voltage difference meets the third preset condition.

[0015] In some of these embodiments, the first preset condition is that the first voltage difference is greater than a first preset value, the second preset condition is that the second voltage difference is less than or equal to a second preset value, the third preset condition is that the third voltage difference is greater than a third preset value, and the fourth preset condition is that the fourth voltage difference is less than or equal to a fourth preset value.

[0016] In some embodiments, after the inverter system enters grid-connected operating mode, the method further includes:

[0017] In response to the input first mode switching command, the relays of the grid-connected relay unit and the bypass relay unit are disconnected, and the relays of the off-grid relay unit are closed.

[0018] The fifth voltage difference between the voltages on both sides of the bypass relay unit is detected, and it is determined whether the fifth voltage difference is greater than a fifth preset value.

[0019] If not, it is determined that the relay of the bypass relay unit has a sticking fault; if so, the sixth voltage difference between the voltages on both sides of the off-grid relay unit is detected, and it is determined whether the sixth voltage difference is less than or equal to the sixth preset value.

[0020] If not, it is determined that the relay of the off-grid relay unit has a non-engaging fault; if so, the inverter system enters the off-grid operating mode.

[0021] In some embodiments, after entering the off-grid working mode, the method further includes:

[0022] In response to the input second mode switching command, the relay of the off-grid relay unit is disconnected, and the grid-connected working mode detection process is entered.

[0023] In some embodiments, the method further includes: when at least one relay of the grid-connected relay unit, the off-grid relay unit, and the bypass relay unit is closed, switching the power supply voltage of the relay from a first voltage to a second voltage; the first voltage is greater than the second voltage.

[0024] In some embodiments, the relay of the bypass relay unit is provided with a first control signal and a second control signal. When the first control signal and the second control signal are both high, the relay of the bypass relay unit is closed.

[0025] The relay that closes the bypass relay unit includes:

[0026] Set both the first control signal and the second control signal of the bypass relay unit to high level.

[0027] Secondly, this embodiment provides a relay fault detection device for an inverter system. The inverter system includes a grid-connected relay unit, an off-grid relay unit, and a bypass relay unit. The device includes a grid-connected operating mode detection module, which includes:

[0028] The detection unit is used to respond to the input fault detection command, detect the first voltage difference between the voltages on both sides of the bypass relay unit, and determine whether the first voltage difference meets the first preset condition.

[0029] The first determining unit is used to determine, if not, that the relay of the bypass relay unit has a sticking fault; if yes, then close the relay of the bypass relay unit, detect the second voltage difference between the voltages on both sides of the bypass relay unit, and determine whether the second voltage difference meets the second preset condition.

[0030] The second determining unit is used to determine, if not, that the relay of the bypass relay unit has a non-engaging fault; if yes, it detects the third voltage difference between the voltages on both sides of the off-grid relay unit and determines whether the third voltage difference meets the third preset condition.

[0031] The third determining unit is used to determine, if not, that there is a sticking fault in the relay of the grid-connected relay unit or the relay of the off-grid relay unit; if yes, it closes the relay of the grid-connected relay unit, detects the fourth voltage difference between the voltages on both sides of the off-grid relay unit, and determines whether the fourth voltage difference meets the fourth preset condition.

[0032] The fourth determining unit is used to determine if the grid-connected relay unit has a non-engaging fault if not, and if so, the inverter system enters the grid-connected working mode.

[0033] Thirdly, this embodiment provides an inverter system including a grid-connected relay unit, an off-grid relay unit, a bypass relay unit, and a controller, wherein the controller is used to execute the relay fault detection method of the inverter system described in any one of the first aspects.

[0034] Fourthly, this embodiment provides a computer-readable storage medium having a computer program stored thereon, characterized in that the computer program, when executed by a processor, implements the steps of the relay fault detection method for the inverter system described in the first aspect.

[0035] Compared with the prior art, the relay fault detection method, device and inverter system of the inverter system provided in this embodiment detects the third voltage difference between the two sides of the off-grid relay unit when the relay of the bypass relay unit is normally closed, and determines whether the third voltage difference meets the third preset condition. Based on whether the third voltage difference meets the third preset condition, it is also determined whether the relays of the grid-connected relay unit and the off-grid relay unit are normally open. By judging the voltage difference once, it is possible to determine whether the relays of the grid-connected relay unit and the off-grid relay unit are normally open, thereby shortening the detection time of relay fault detection in the inverter system and solving the problem of long detection time of relay fault detection in the prior art.

[0036] Details of one or more embodiments of this application are set forth in the following drawings and description to make other features, objects and advantages of this application more readily apparent. Attached Figure Description

[0037] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0038] Figure 1 This is a hardware structure block diagram of a terminal executing a relay fault detection method for an inverter system according to an embodiment of this application;

[0039] Figure 2 This is a flowchart of a relay fault detection method for an inverter system according to an embodiment of this application;

[0040] Figure 3 This is a flowchart of the off-network working mode detection process according to an embodiment of this application;

[0041] Figure 4 This is a schematic diagram of the inverter system in this specific embodiment;

[0042] Figure 5 This is a schematic diagram of a structure in the grid-connected working mode detection process of the inverter system in this specific embodiment;

[0043] Figure 6 This is a schematic diagram of a structure in the grid-connected working mode detection process of the inverter system in this specific embodiment;

[0044] Figure 7 This is a schematic diagram of a structure in the grid-connected working mode detection process of the inverter system in this specific embodiment;

[0045] Figure 8 This is a schematic diagram of a structure in the grid-connected working mode detection process of the inverter system in this specific embodiment;

[0046] Figure 9 This is a schematic diagram of a structure in the grid-connected working mode detection process of the inverter system in this specific embodiment;

[0047] Figure 10 This is a schematic diagram of the off-grid operating mode detection process of the inverter system in this specific embodiment;

[0048] Figure 11 This is a structural block diagram of a relay fault detection device for an inverter system according to an embodiment of this application. Detailed Implementation

[0049] To better understand the purpose, technical solution, and advantages of this application, the application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0050] Unless otherwise defined, the technical or scientific terms used in this application shall have the general meaning as understood by one of ordinary skill in the art to which this application pertains. Words such as “a,” “an,” “an,” “the,” “the,” and “these,” used in this application, do not indicate quantitative limitation and may be singular or plural. The terms “comprising,” “including,” “having,” and any variations thereof used in this application are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or device that comprises a series of steps or modules (units) is not limited to the listed steps or modules (units) but may include steps or modules (units) not listed, or may include other steps or modules (units) inherent to such processes, methods, products, or devices. The terms “connected,” “linked,” and “coupled,” used in this application, are not limited to physical or mechanical connections but may include electrical connections, whether direct or indirect. The term “multiple” used in this application refers to two or more. The "and / or" operator describes the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: A alone, A and B simultaneously, and B alone. Typically, the character " / " indicates that the objects before and after it are in an "or" relationship. The terms "first," "second," and "third," etc., used in this application are merely for distinguishing similar objects and do not represent a specific ordering of the objects.

[0051] The method embodiments provided in this example can be executed on a terminal, computer, or similar computing device. For example, it can run on a terminal. Figure 1 This is a hardware structure block diagram of a terminal executing a relay fault detection method for an inverter system according to an embodiment of this application. For example... Figure 1 As shown, the terminal may include one or more ( Figure 1 Only one is shown in the diagram. A processor 102 and a memory 104 for storing data are also included. The processor 102 may be, but is not limited to, a microprocessor (MCU) or a programmable logic device (FPGA). The terminal may also include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that… Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the terminal described above. For example, the terminal may also include components that are larger than... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown are illustrated.

[0052] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to a relay fault detection method for an inverter system in this embodiment. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, thereby implementing the aforementioned method. The memory 104 may include high-speed random access memory and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the terminal via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0053] The transmission device 106 is used to receive or send data via a network. This network includes a wireless network provided by the terminal's communication provider. In one example, the transmission device 106 includes a Network Interface Controller (NIC), which can connect to other network devices via a base station to communicate with the Internet. In another example, the transmission device 106 can be a Radio Frequency (RF) module used for wireless communication with the Internet.

[0054] This embodiment provides a relay fault detection method for an inverter system. Figure 2 This is a flowchart illustrating a relay fault detection method for an inverter system according to an embodiment of this application. The inverter system includes a grid-connected relay unit, an off-grid relay unit, and a bypass relay unit. The relay fault detection method for the inverter system includes a grid-connected operating mode detection process, such as... Figure 2 As shown, the grid-connected operating mode detection process includes the following steps:

[0055] In step S210, all relays are disconnected. In response to the input fault detection command, the first voltage difference between the voltages on both sides of the bypass relay unit is detected, and it is determined whether the first voltage difference meets the first preset condition.

[0056] Specifically, in the inverter's grid-connected operating mode, all relays in the grid-connected relay unit are closed, all relays in the bypass relay unit are closed, and all relays in the off-grid relay unit are open. Upon entering the grid-connected operating mode detection process, all relays of the inverter are first opened. Responding to the user-inputted fault detection command, the relays in the bypass relay unit are first checked to see if they are properly open. The first voltage difference across the bypass relay unit is detected, and based on whether this first voltage difference meets a first preset condition, it is determined whether the bypass relay unit's relays are properly open.

[0057] For example, the first preset condition here can be a first voltage difference greater than a first preset value. When the first voltage difference is greater than the first preset value, it is determined that the relay of the bypass relay unit is normally disconnected; when the first voltage difference is less than or equal to the first preset value, it is determined that the relay of the bypass relay unit has a sticking fault.

[0058] It should be noted that when the bypass relay unit is normally open, the voltage difference across the bypass relay unit is relatively large, typically several hundred volts. When the bypass relay unit is closed and conducting, the voltage difference across the bypass relay unit is relatively small, typically a few volts. Therefore, the normal openness of the bypass relay unit can be determined by judging the relationship between the first voltage difference across the bypass relay unit and the first preset value.

[0059] Step S220: If the first voltage difference does not meet the first preset condition, it is determined that the relay of the bypass relay unit has a sticking fault; if the first voltage difference meets the first preset condition, the relay of the bypass relay unit is closed, the second voltage difference between the voltages on both sides of the bypass relay unit is detected, and it is determined whether the second voltage difference meets the second preset condition.

[0060] Specifically, when the first voltage difference across the bypass relay unit does not meet the first preset condition (i.e., the first voltage difference is less than or equal to the first preset value), it is determined that the relay in the bypass relay unit has a sticking fault. When the first voltage difference across the bypass relay unit meets the first preset condition (i.e., the first voltage difference is greater than the first preset value), it is determined that the relay in the bypass relay unit is normally open. When the relay in the bypass relay unit can normally open, the relay in the bypass relay unit is closed, the second voltage difference across the bypass relay unit is detected, and it is determined whether the second voltage difference meets the second preset condition. Based on whether the second voltage difference meets the second preset condition, it is determined whether the relay in the bypass relay unit is normally closed.

[0061] For example, the second preset condition here is that the second voltage difference is less than or equal to the second preset value. When the second voltage difference is less than or equal to the second preset value, it is determined that the relay of the bypass relay unit is normally closed; when the second voltage difference is greater than the second preset value, it is determined that the relay of the bypass relay unit is faulty. The first preset value and the second preset value here can be the same or different, and are not specifically limited here.

[0062] Step S230: If the second voltage difference does not meet the second preset condition, it is determined that the relay of the bypass relay unit has a non-engaging fault; if the second voltage difference meets the second preset condition, the third voltage difference between the voltages on both sides of the off-grid relay unit is detected, and it is determined whether the third voltage difference meets the third preset condition.

[0063] Specifically, when the second voltage difference across the bypass relay unit does not meet the second preset condition (i.e., the second voltage difference is greater than the second preset value), it is determined that the relay in the bypass relay unit has a non-closing fault, meaning the relay in the bypass relay unit is not closing properly. When the second voltage difference across the bypass relay unit meets the second preset condition (i.e., the second voltage difference is less than or equal to the second preset value), it is determined that the relay in the bypass relay unit is closing normally. When the relay in the bypass relay unit is closing normally, the third voltage difference across the off-grid relay unit is detected, and it is determined whether the third voltage difference meets the third preset condition. Based on whether the third voltage difference meets the third preset condition, it is determined whether the relays in the grid-connected relay unit and the off-grid relay unit are normally disconnected.

[0064] For example, the third preset condition here is that the third voltage difference is greater than the third preset value. When the third voltage difference is less than or equal to the third preset value, it is determined that the relay in the grid-connected relay unit or the relay in the off-grid relay unit has a sticking fault; when the third voltage difference is greater than the third preset value, it is determined that the relays in both the grid-connected relay unit and the off-grid relay unit are normally disconnected. The third preset value here can be the same as or different from the first and second preset values, and is not specifically limited here.

[0065] It should be noted that when both the relays in the grid-connected relay unit and the relays in the off-grid relay unit are normally open, the voltage difference across the off-grid relay unit is relatively large, typically several hundred volts. When either the relay in the grid-connected relay unit or the relay in the off-grid relay unit is closed and conducting, the voltage difference across the relay is very small, typically a few volts. Therefore, the relationship between the third voltage difference across the off-grid relay unit and the third preset value can be used to determine whether the relays in the grid-connected relay unit and the off-grid relay unit are normally open.

[0066] Step S240: If the third voltage difference does not meet the third preset condition, it is determined that the relay of the grid-connected relay unit or the relay of the off-grid relay unit has a sticking fault; if the third voltage difference meets the third preset condition, the relay of the grid-connected relay unit is closed, the fourth voltage difference between the voltages on both sides of the off-grid relay unit is detected, and it is determined whether the fourth voltage difference meets the fourth preset condition.

[0067] Specifically, when the third voltage difference across the off-grid relay unit does not meet the third preset condition (i.e., the third voltage difference is less than or equal to the third preset value), it is determined that either the relay in the grid-connected relay unit or the relay in the off-grid relay unit has a sticking fault. When the third voltage difference across the off-grid relay unit meets the third preset condition (i.e., the third voltage difference is greater than the third preset value), it is determined that both the relays in the grid-connected relay unit and the off-grid relay unit are normally disconnected. With both relays in the grid-connected relay unit and the off-grid relay unit normally disconnected, the relay in the grid-connected relay unit is closed, the fourth voltage difference across the off-grid relay unit is detected, and it is determined whether the fourth voltage difference meets the fourth preset condition. Based on whether the fourth voltage difference meets the fourth preset condition, it is determined whether the relay in the grid-connected relay unit is normally closed.

[0068] For example, the fourth preset condition here is that the fourth voltage difference is less than or equal to the fourth preset value. When the fourth voltage difference is less than or equal to the fourth preset value, it is determined that the relay of the grid-connected relay unit is normally closed; when the fourth voltage difference is greater than the fourth preset value, it is determined that the relay of the grid-connected relay unit is faulty. The fourth preset value here may be the same as or different from the first, second, and third preset values, and no specific limitation is made here.

[0069] In step S250, if the fourth voltage difference does not meet the fourth preset condition, it is determined that the relay of the grid-connected relay unit has a non-engaging fault; if the fourth voltage difference meets the fourth preset condition, the inverter system enters the grid-connected working mode.

[0070] Specifically, when the fourth voltage difference across the off-grid relay unit does not meet the fourth preset condition (i.e., the fourth voltage difference is greater than the fourth preset value), it is determined that the relay in the grid-connected relay unit has a non-closing fault. When the fourth voltage difference across the off-grid relay unit meets the fourth preset condition (i.e., the fourth voltage difference is less than or equal to the fourth preset value), it is determined that the relay in the grid-connected relay unit is normally closed. Under the condition that the relay in the grid-connected relay unit is normally closed, the inverter system enters the grid-connected operating mode. In the grid-connected operating mode, all relays in the grid-connected relay unit are closed, all relays in the bypass relay unit are closed, and all relays in the off-grid relay unit are open.

[0071] In this embodiment, by detecting the third voltage difference between the two sides of the off-grid relay unit when the relay of the bypass relay unit is normally closed, and determining whether the third voltage difference meets the third preset condition, it is simultaneously determined whether the relays of the grid-connected relay unit and the off-grid relay unit are normally open based on whether the third voltage difference meets the third preset condition. By determining the voltage difference once, it is possible to simultaneously determine whether the relays of the grid-connected relay unit and the off-grid relay unit are normally open, thereby shortening the fault detection time of the inverter system relays and solving the problem of long fault detection time of the inverter system relays in the prior art.

[0072] In some embodiments, if the second voltage difference meets the second preset condition, the third voltage difference between the voltages on both sides of the off-grid relay unit is detected, and it is determined whether the third voltage difference meets the third preset condition. This includes: when the second voltage difference meets the second preset condition, closing at least one set of relays in the grid-connected relay unit; after closing at least one set of relays in the grid-connected relay unit, detecting the third voltage difference between the voltages on both sides of the off-grid relay unit, and determining whether the third voltage difference meets the third preset condition.

[0073] Specifically, the grid-connected relay unit includes M relay groups. Each relay group includes N relays, and the N relays in each relay group belong to different circuit branches. Here, M is an integer greater than or equal to 2, and N is an integer greater than or equal to 2. To determine whether the N relays in relay group i are normally open, the other M-1 relay groups in the grid-connected relay unit (excluding relay group i) are closed. The third voltage difference across the off-grid relay unit is detected. When the third voltage difference is greater than a third preset value, it is determined that the relays in relay group i of the grid-connected relay unit and the relays in the off-grid relay unit are normally open. The same method is used to determine whether the relays in the other M-1 relay groups in the grid-connected relay unit are normally open.

[0074] In some embodiments, after the inverter system enters grid-connected operating mode, the relay fault detection method for the inverter system also includes an off-grid operating mode detection process, such as... Figure 3 As shown, the off-grid working mode detection process includes the following steps:

[0075] In step S310, in response to the input first mode switching command, the relays of the grid-connected relay unit and the bypass relay unit are disconnected, and the relays of the off-grid relay unit are closed.

[0076] Specifically, in off-grid operating mode, all relays in the bypass relay unit are disconnected, and all relays in the off-grid relay unit are closed. In response to a user-inputted first mode switching command, which instructs the inverter system to switch its operating mode from grid-connected to off-grid operating mode, all relays in the grid-connected relay unit and the bypass relay unit are disconnected, and all relays in the off-grid relay unit are closed.

[0077] Step S320: Detect the fifth voltage difference between the two sides of the bypass relay unit and determine whether the fifth voltage difference is greater than the fifth preset value.

[0078] Specifically, after disconnecting all relays in the grid-connected relay unit and all relays in the bypass relay unit, and closing all relays in the off-grid relay unit, the fifth voltage difference across the bypass relay unit is detected, and it is determined whether this fifth voltage difference is greater than a fifth preset value. Based on whether this fifth voltage difference is greater than the fifth preset value, it is determined whether the relays in the bypass relay unit have been properly disconnected. The fifth preset value here can be the same as or different from the first, second, third, and fourth preset values; no specific limitation is made here.

[0079] In step S330, if the fifth voltage difference is less than or equal to the fifth preset value, it is determined that the relay of the bypass relay unit has a sticking fault; if the fifth voltage difference is greater than the fifth preset value, the sixth voltage difference between the voltages on both sides of the off-grid relay unit is detected, and it is determined whether the sixth voltage difference is less than or equal to the sixth preset value.

[0080] Specifically, if the fifth voltage difference is greater than the fifth preset value, then it is determined that all relays in the bypass relay unit are normally disconnected. After determining that all relays in the bypass relay unit are normally disconnected, the sixth voltage difference across the off-grid relay unit is detected, and it is determined whether the sixth voltage difference is less than or equal to the sixth preset value. Based on whether the sixth voltage difference is less than or equal to the sixth preset value, it is determined whether all relays in the off-grid relay unit are normally closed. The sixth preset value here can be the same as or different from the first, second, third, fourth, and fifth preset values; no specific limitation is made here.

[0081] Step S340: If the sixth voltage difference is greater than the sixth preset value, it is determined that the relay of the off-grid relay unit has a non-engaging fault; if the sixth voltage difference is less than or equal to the sixth preset value, the inverter system enters the off-grid working mode.

[0082] Specifically, if the sixth voltage difference is less than or equal to the sixth preset value, it is determined that all relays in the off-grid relay unit are normally closed, and the inverter system enters the off-grid operating mode. In the off-grid operating mode, all relays in the bypass relay unit are open, and all relays in the off-grid relay unit are closed.

[0083] In this embodiment, in response to the input first mode switching command, the relays of the inverter system are closed or opened, and the operating mode of the inverter system is automatically switched from grid-connected operating mode to off-grid operating mode by judging the voltage difference.

[0084] In some embodiments, after the inverter system enters the off-grid operating mode, the relay fault detection method of the inverter system further includes: in response to the input second mode switching command, disconnecting the relay of the off-grid relay unit and entering the grid-connected operating mode detection process.

[0085] Specifically, in response to the second mode switching command input by the user, the relay of the off-grid relay unit is disconnected, and the grid-connected working mode detection process is entered. The second mode switching command is used to indicate that the working mode of the inverter system is switched from off-grid working mode to grid-connected working mode.

[0086] In some embodiments, the relay fault detection method of the inverter system further includes: when at least one relay of the grid-connected relay unit, the off-grid relay unit, and the bypass relay unit is closed, switching the power supply voltage of the relay from a first voltage to a second voltage; the first voltage is greater than the second voltage.

[0087] In some embodiments, the relay of the bypass relay unit is provided with a first control signal and a second control signal. When the first control signal and the second control signal are both at a high level, the relay of the bypass relay unit is closed. Closing the relay of the bypass relay unit includes setting both the first control signal and the second control signal of the bypass relay unit to a high level.

[0088] This embodiment also provides an inverter system, which includes a grid-connected relay unit, an off-grid relay unit, a bypass relay unit, and a controller. The controller is used to execute the relay fault detection method of the inverter system described in the foregoing embodiment.

[0089] The embodiments of this application will be described and illustrated below through specific examples.

[0090] Figure 4 This is a schematic diagram of the inverter system in this specific embodiment, as shown below. Figure 4As shown, the split-phase inverter system includes: a grid-connected relay unit, an off-grid relay unit, a bypass relay unit, an inverter INV, a grid, and a load EPS. One end of the grid-connected relay unit is connected to the inverter INV, and the other end is connected to the grid. One end of the off-grid relay unit is connected to the inverter INV, and the other end is connected to the load EPS. One end of the bypass relay unit is connected to the grid, and the other end is connected to the load EPS. The inverter system also includes a capacitor C. xA Capacitor C xB And mutual inductor CT. For example... Figure 4 As shown, the voltage detection points include: V inv_L1_N V inv_L2_N V inv_N V grid_L1_N V grid_L2_N V load_L1_N V load_L2_N 、 and V N The voltage at the voltage detection point can be acquired by the data acquisition unit through the current transformer (CT), or by other acquisition units.

[0091] Specifically, the grid-connected relay unit includes relays Rly11, Rly12, Rly13, and Rly14. The off-grid relay unit includes relays Rly21, Rly22, and Rly51. The bypass relay unit includes relays Rly31 and Rly32, and relay Rly51 is the neutral (N) side relay. One end of relay Rly11 is connected to the L1 port of the inverter INV; the other end of relay Rly11 is connected to one end of relay Rly12; the other end of relay Rly12 is connected to the L1 port of the grid. One end of relay Rly13 is connected to the L2 port of the inverter INV; the other end of relay Rly13 is connected to one end of relay Rly14; the other end of relay Rly14 is connected to the L2 port of the grid. One end of relay Rly21 is connected to the L1 port of the inverter INV; the other end of relay Rly21 is connected to the L1 port of the load EPS. One end of relay Rly22 is connected to the L2 port of inverter INV, and the other end of relay Rly22 is connected to the L2 port of load EPS. One end of relay Rly51 is connected to the N port of inverter INV, and the other end of relay Rly51 is connected to the N port of load EPS.

[0092] The inverter system in this specific embodiment is divided into grid-connected working mode and off-grid working mode. In grid-connected working mode, the energy flow is that the grid provides energy to the load EPS and the grid flows through the inverter INV and is rectified to provide energy to the front stage. In off-grid working mode, the inverter INV only inverts to provide energy to the load EPS.

[0093] The following is a detailed explanation of the grid-connected working mode testing process.

[0094] like Figure 5 As shown, first check whether relay Rly51 disconnects normally, and then check the voltage detection point V. inv_N and V N The detected voltage values ​​are subtracted; if the difference is not zero, relay Rly51 is determined to have disconnected normally. Additionally, relays Rly31 and Rly32 are checked for normal disconnection, and the voltage detection point V is... grid_L1_N and V load_L1_N The detected voltage values ​​are subtracted. If the difference is not zero, the relay Rly31 is determined to be normally disconnected, and the voltage detection point V is adjusted accordingly. grid_L2_N and V load_L2_N The detected voltage values ​​are subtracted; if the difference is not zero, relay Rly32 is considered to have disconnected normally. Figure 6 As shown, when relays Rly51, Rly31, and Rly32 are all normally open, closing relays Rly31 and Rly32 will affect the voltage detection point V. grid_L1_N and V load_L1_N The detected voltage values ​​are subtracted; when the difference is 0, relay Rly31 is considered to be normally closed; for voltage detection point V... grid_L2_N and V load_L2_N The detected voltage values ​​are subtracted; if the difference is 0, relay Rly32 is considered to be normally closed. Figure 7 As shown, when relays Rly31 and Rly32 are both closed normally, closing relays Rly12 and Rly14 will affect the voltage detection point V. inv_L1_N and V load_L1_N The detected voltage values ​​are subtracted; if the difference is not 0, it is determined that relays Rly11 and Rly21 are normally disconnected; for voltage detection point V... inv_L2_N and V load_L2_N The detected voltage values ​​are subtracted; if the difference is not zero, it is determined that relays Rly13 and Rly22 are normally disconnected. Figure 8 As shown, when relays Rly11, Rly13, Rly21, and Rly22 are all normally disconnected, relays Rly12 and Rly14 are disconnected, and relays Rly11 and Rly13 are closed, thus affecting the voltage detection point V. inv_L1_N and V load_L1_NThe detected voltage values ​​are subtracted; if the difference is not 0, it is determined that relay Rly12 has been normally disconnected; for voltage detection point V... inv_L2_N and V load_L2_N The detected voltage values ​​are subtracted; if the difference is not zero, it is determined that relay Rly14 has normally disconnected. Figure 9 As shown, when relays Rly11, Rly12, Rly13, Rly14, Rly21, and Rly22 are all normally open, closing relays Rly11, Rly12, Rly13, and Rly14 will affect the voltage detection point V. inv_L1_N and V load_L1_N The detected voltage values ​​are subtracted, and the voltage detection point V is calculated. inv_L2_N and V load_L2_N The detected voltage values ​​are subtracted. When all subtraction values ​​are 0, it is determined that relays Rly11, Rly12, Rly13 and Rly14 are closed normally. If the closure is successful, the inverter system enters grid-connected operation mode.

[0095] During the grid-connected operating mode test, when relays Rly31 and Rly32 are both closed normally, relays Rly12 and Rly14 are closed, and the voltage detection point V is checked. inv_L1_N and V load_L1_N The detected voltage values ​​are subtracted; if the difference is not 0, it is determined that relays Rly11 and Rly21 are normally disconnected; for voltage detection point V... inv_L2_N and V load_L2_N The detected voltage values ​​are subtracted; if the difference is not 0, it is determined that relays Rly13 and Rly22 are normally disconnected. This is then verified by monitoring the voltage detection point V. inv_L1_N and V load_L1_N The voltage value or voltage detection point V inv_L2_N and V load_L2_N A single voltage test simultaneously detects relay Rly11 of the grid-connected relay unit and relay Rly21 of the off-grid relay unit, or simultaneously detects relay Rly13 of the grid-connected relay unit and relay Rly22 of the off-grid relay unit, saving testing steps and making the testing process faster.

[0096] The following is a detailed explanation of the off-grid working mode detection process.

[0097] like Figure 9 As shown, the inverter system is in grid-connected operation mode. When a fault occurs in the inverter system, it is necessary to switch the inverter system's operation mode from grid-connected to off-grid operation mode, as follows: Figure 10As shown, disconnecting relays Rly11, Rly12, Rly13, Rly14, Rly31, and Rly32 causes a grid power outage. At this time, closing relays Rly21, Rly22, and Rly51 causes the inverter system to enter off-grid low-voltage operation. If the voltage detection point V... inv_N and V N When the difference in detected voltage values ​​is 0, relay Rly51 is considered to be normally closed; if the voltage detection point V inv_L1_N and V load_L1_N When the difference in detected voltage values ​​is 0, relay Rly21 is considered to be normally closed; if the voltage detection point V inv_L2_N and V load_L2_N When the detected voltage difference is 0, Rly22 is considered to be normally closed. To avoid the risk of the grid side becoming energized due to the closure of relays Rly31 and Rly32 during off-grid operation, the normal opening of relays Rly31 and Rly32 is checked again, and V is measured. grid_L1_N and V load_L1_N If the difference is not zero, it is determined that relay Rly31 is normally disconnected; V is then checked. grid_L2_N and V load_L2_N If the difference is not zero, it is determined that relay Rly32 has been normally disconnected. At this time, the inverter system is operating in off-grid mode.

[0098] When the inverter system fault is resolved, the inverter system's operating mode is switched from off-grid mode to grid-connected mode, such as... Figure 10 As shown, the inverter system is in off-grid operation mode. When the inverter system fault is detected to be resolved, i.e., the grid is restored, relays Rly21, Rly22, and Rly51 are disconnected, and the grid-connected operation mode detection process in this specific embodiment is executed.

[0099] It should be noted that determining whether the voltage difference between two detected voltage points is zero includes: if the absolute value of the difference is less than or equal to a preset voltage threshold, the voltage difference is determined to be zero; if the absolute value of the difference is greater than the preset voltage threshold, the voltage difference is determined to be non-zero. The preset voltage threshold can be set according to the actual situation of the inverter system, for example, a voltage value less than 10 volts.

[0100] Furthermore, in this specific embodiment of the inverter system relays, the first control signal controls the power supply signal to supply 12V, causing relays Rly11, Rly12, Rly13, Rly14, Rly21, Rly22, Rly41, Rly42, and Rly51 to conduct. Then, the first control signal controls the 12V power supply to be disconnected and switched to 7V power supply, which can keep the relays closed, thereby reducing relay losses. For the bypass relays Rly31 and Rly32, dual drive control is adopted. Only when both the first and second control signals are high can the power supply signal to supply 12V be controlled to conduct relays Rly31 and Rly32. Similarly, when the first and second control signals are low, the power supply signal is switched to 7V, which can reduce relay losses. For relays Rly31 and Rly32, a dual-drive control is adopted. Only when the first control signal and the second control signal are both high will the 12V voltage enter the relay power supply terminal. Interference or false triggering will cause one signal to go high, which will not affect the power supply signal. This measure can reliably disconnect the off-grid machine from the grid in the event of a grid fault, greatly reducing the risk of electric shock to grid maintenance personnel and reliably ensuring their safety.

[0101] This embodiment uses a split-phase inverter system as an example for description. It can be understood that the relay fault detection method for inverter systems provided in this application can also be applied to other inverter systems.

[0102] It should be noted that the steps shown in the above process or in the flowchart of the accompanying figures can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0103] This embodiment also provides a relay fault detection device for an inverter system, which is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. The terms "module," "unit," "subunit," etc., used below refer to combinations of software and / or hardware that implement a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0104] Figure 11 This is a structural block diagram of a relay fault detection device for an inverter system according to an embodiment of this application. The inverter system includes a grid-connected relay unit, an off-grid relay unit, and a bypass relay unit. The device includes a grid-connected operating mode detection module, such as... Figure 11 As shown, the grid-connected operating mode detection module includes:

[0105] The detection unit 510 is used to disconnect all relays, respond to the input fault detection command, detect the first voltage difference between the voltages on both sides of the bypass relay unit, and determine whether the first voltage difference meets the first preset condition.

[0106] The first determining unit 520 is used to determine that the relay of the bypass relay unit has a sticking fault if the first voltage difference does not meet the first preset condition; and to close the relay of the bypass relay unit if the first voltage difference meets the first preset condition, detect the second voltage difference between the voltages on both sides of the bypass relay unit, and determine whether the second voltage difference meets the second preset condition.

[0107] The second determining unit 530 is used to determine that the relay of the bypass relay unit has a non-engaging fault if the second voltage difference does not meet the second preset condition; and to detect the third voltage difference between the voltages on both sides of the off-grid relay unit and determine whether the third voltage difference meets the third preset condition if the second voltage difference meets the second preset condition.

[0108] The third determining unit 540 is used to determine that if the third voltage difference does not meet the third preset condition, the relay of the grid-connected relay unit or the relay of the off-grid relay unit has a sticking fault; if the third voltage difference meets the third preset condition, the relay of the grid-connected relay unit is closed, the fourth voltage difference between the voltages on both sides of the off-grid relay unit is detected, and it is determined whether the fourth voltage difference meets the fourth preset condition.

[0109] The fourth determining unit 550 is used to determine that the relay of the grid-connected relay unit has a non-engaging fault if the fourth voltage difference does not meet the fourth preset condition; and if the fourth voltage difference meets the fourth preset condition, the inverter system enters the grid-connected working mode.

[0110] It should be noted that the above modules can be functional modules or program modules, and can be implemented through software or hardware. For modules implemented through hardware, the above modules can reside in the same processor; or the above modules can be located in different processors in any combination.

[0111] This embodiment also provides an electronic device including a memory and a processor, the memory storing a computer program and the processor being configured to run the computer program to perform the steps in any of the above method embodiments.

[0112] Optionally, the electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor and the input / output device is connected to the processor.

[0113] Optionally, in this embodiment, the processor can be configured to perform the following steps via a computer program:

[0114] S1, all relays are disconnected. In response to the input fault detection command, the first voltage difference between the voltages on both sides of the bypass relay unit is detected, and it is determined whether the first voltage difference meets the first preset condition.

[0115] S2, if the first voltage difference does not meet the first preset condition, it is determined that the relay of the bypass relay unit has a sticking fault; if the first voltage difference meets the first preset condition, the relay of the bypass relay unit is closed, the second voltage difference between the voltages on both sides of the bypass relay unit is detected, and it is determined whether the second voltage difference meets the second preset condition.

[0116] S3, if the second voltage difference does not meet the second preset condition, it is determined that the relay of the bypass relay unit has a non-engaging fault; if the second voltage difference meets the second preset condition, the third voltage difference between the voltages on both sides of the off-grid relay unit is detected, and it is determined whether the third voltage difference meets the third preset condition.

[0117] S4. If the third voltage difference does not meet the third preset condition, it is determined that the relay of the grid-connected relay unit or the relay of the off-grid relay unit has a sticking fault; if the third voltage difference meets the third preset condition, the relay of the grid-connected relay unit is closed, the fourth voltage difference between the voltages on both sides of the off-grid relay unit is detected, and it is determined whether the fourth voltage difference meets the fourth preset condition.

[0118] S5. If the fourth voltage difference does not meet the fourth preset condition, it is determined that the relay of the grid-connected relay unit has a non-engaging fault; if the fourth voltage difference meets the fourth preset condition, the inverter system enters the grid-connected working mode.

[0119] It should be noted that the specific examples in this embodiment can refer to the examples described in the above embodiments and optional implementations, and will not be repeated in this embodiment.

[0120] Furthermore, in conjunction with the relay fault detection method for an inverter system provided in the above embodiments, this embodiment can also provide a storage medium for implementation. The storage medium stores a computer program; when executed by a processor, the computer program implements the steps of any of the relay fault detection methods for an inverter system in the above embodiments.

[0121] It should be understood that the specific embodiments described herein are merely illustrative of the application and not intended to limit it. All other embodiments derived by those skilled in the art based on the embodiments provided in this application without inventive effort are within the scope of protection of this application.

[0122] Obviously, the accompanying drawings are merely some examples or embodiments of this application. Those skilled in the art can apply this application to other similar situations based on these drawings without any creative effort. Furthermore, it is understood that although the work done in this development process may be complex and lengthy, for those skilled in the art, certain design, manufacturing, or production modifications made based on the technical content disclosed in this application are merely conventional technical means and should not be considered as insufficient disclosure of this application.

[0123] The term "embodiment" in this application refers to a specific feature, structure, or characteristic described in connection with an embodiment that may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily imply the same embodiment, nor does it imply that it is mutually exclusive with or independent of other embodiments. It will be clearly or implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0124] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of patent protection. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A method of detecting a relay fault of an inverter system, characterized by, The inverter system comprises a grid-connected relay unit, an off-grid relay unit and a bypass relay unit, the method comprises a grid-connected operation mode detection process, the grid-connected operation mode detection process comprises: all relays are opened, in response to an input fault detection instruction, a first voltage difference of voltages on both sides of the bypass relay unit is detected, and it is determined whether the first voltage difference meets a first preset condition; if not, it is determined that the relays of the bypass relay unit have a sticking fault; if yes, a relay of the bypass relay unit is closed, a second voltage difference of voltages on both sides of the bypass relay unit is detected, and it is determined whether the second voltage difference meets a second preset condition; if not, it is determined that the relay of the bypass relay unit has a non-attractive fault; if yes, a third voltage difference of voltages on both sides of the off-grid relay unit is detected, and it is determined whether the third voltage difference meets a third preset condition; if not, it is determined that the relay of the grid-connected relay unit or the relay of the off-grid relay unit has a sticking fault; if yes, a relay of the grid-connected relay unit is closed, a fourth voltage difference of voltages on both sides of the off-grid relay unit is detected, and it is determined whether the fourth voltage difference meets a fourth preset condition; if not, it is determined that the relay of the grid-connected relay unit has a non-attractive fault; if yes, the inverter system enters a grid-connected operation mode; wherein the first preset condition is that the first voltage difference is greater than a first preset value, the second preset condition is that the second voltage difference is less than or equal to a second preset value, the third preset condition is that the third voltage difference is greater than a third preset value, and the fourth preset condition is that the fourth voltage difference is less than or equal to a fourth preset value.

2. The relay fault detection method of an inverter system according to claim 1, characterized by, The if yes, a third voltage difference of voltages on both sides of the off-grid relay unit is detected, and it is determined whether the third voltage difference meets a third preset condition, comprises: when the second voltage difference meets the second preset condition, at least one group of relays of the grid-connected relay unit is closed; after the at least one group of relays of the grid-connected relay unit is closed, a third voltage difference of voltages on both sides of the off-grid relay unit is detected, and it is determined whether the third voltage difference meets a third preset condition.

3. The method of claim 1, wherein the relay fault detection method of the inverter system is characterized by, After the inverter system enters the grid-connected operation mode, the method further comprises: in response to an input first mode switching instruction, the relays of the grid-connected relay unit and the relays of the bypass relay unit are opened, and the relays of the off-grid relay unit are closed; a fifth voltage difference of voltages on both sides of the bypass relay unit is detected, and it is determined whether the fifth voltage difference is greater than a fifth preset value; if not, it is determined that the relays of the bypass relay unit have a sticking fault; if yes, a sixth voltage difference of voltages on both sides of the off-grid relay unit is detected, and it is determined whether the sixth voltage difference is less than or equal to a sixth preset value; if not, it is determined that the relays of the off-grid relay unit have a non-attractive fault; if yes, the inverter system enters an off-grid operation mode.

4. The relay fault detection method of an inverter system according to claim 3, characterized by, After entering the off-network working mode, the method further includes: In response to the input second mode switching command, the relay of the off-grid relay unit is disconnected, and the grid-connected working mode detection process is entered.

5. The method of claim 1, wherein, The method further includes: when at least one of the relays of the grid-connected relay unit, the off-grid relay unit, and the bypass relay unit is closed, switching the power supply voltage of the relay from a first voltage to a second voltage; the first voltage is greater than the second voltage.

6. The method of claim 1, wherein, The bypass relay unit is equipped with a first control signal and a second control signal. When both the first control signal and the second control signal are at a high level, the relay of the bypass relay unit is closed. The relay that closes the bypass relay unit includes: Set both the first control signal and the second control signal of the bypass relay unit to high level.

7. A relay failure detection device of an inverter system characterized by comprising: The inverter system includes a grid-connected relay unit, an off-grid relay unit, and a bypass relay unit. The device includes a grid-connected operating mode detection module, which includes: The detection unit is used to disconnect all relays, respond to the input fault detection command, detect the first voltage difference between the voltages on both sides of the bypass relay unit, and determine whether the first voltage difference meets the first preset condition. The first determining unit is used to determine, if not, that the relay of the bypass relay unit has a sticking fault; if yes, then close the relay of the bypass relay unit, detect the second voltage difference between the voltages on both sides of the bypass relay unit, and determine whether the second voltage difference meets the second preset condition. The second determining unit is used to determine, if not, that the relay of the bypass relay unit has a non-engaging fault; if yes, it detects the third voltage difference between the voltages on both sides of the off-grid relay unit and determines whether the third voltage difference meets the third preset condition. The third determining unit is used to determine, if not, that there is a sticking fault in the relay of the grid-connected relay unit or the relay of the off-grid relay unit; if yes, it closes the relay of the grid-connected relay unit, detects the fourth voltage difference between the voltages on both sides of the off-grid relay unit, and determines whether the fourth voltage difference meets the fourth preset condition. The fourth determining unit is used to determine if the grid-connected relay unit has a non-engaging fault if not; otherwise, the inverter system enters the grid-connected working mode. Wherein, the first preset condition is that the first voltage difference is greater than the first preset value, the second preset condition is that the second voltage difference is less than or equal to the second preset value, the third preset condition is that the third voltage difference is greater than the third preset value, and the fourth preset condition is that the fourth voltage difference is less than or equal to the fourth preset value.

8. An inverter system comprising a grid-connected relay unit, an off-grid relay unit, a bypass relay unit, and a controller, wherein the controller is configured to execute the relay fault detection method of the inverter system according to any one of claims 1 to 6.

9. A computer-readable storage medium having stored thereon a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the relay fault detection method for the inverter system according to any one of claims 1 to 6.

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