Standby power system and power wiring detection method thereof

Abstract

The invention provides a standby power system and a power wiring detection method thereof, and the method comprises the steps: disconnecting a switching circuit in a grid-connected and off-grid controller under the condition that the grid-connected and off-grid controller supplies power through an inverter or a power grid, and starting the wiring detection. And when only the inverter side port or the network side port of the grid-connected and off-grid controller is detected to have the voltage, judging that the conditions that the voltage of the inverter side port is greater than a first threshold value, the output voltage of the inverter is less than the first threshold value and the inverter is in a shutdown or starting process are met at the same time, and reporting the abnormal wiring fault of the network side port. And when it is detected that the inverter side port and the network side port both have the voltage, sending a disturbance instruction to the inverter, so that the inverter adjusts the output voltage according to the disturbance instruction. And when it is judged that the voltage of the network-side port changes along with the output voltage of the inverter, the abnormal wiring fault of the inverter-side port is reported. According to the detection mode, troubleshooting wiring is carried out in a single power supply mode without manual intervention, additional detection assemblies do not need to be added, cost is saved, logic is simple, the speed is high, and detection is accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to a backup power system and a power wiring detection method thereof. Background Art

[0002] The whole-house power backup system is mainly composed of an inverter and an on-grid and off-grid controller. It can provide power through various means such as photovoltaic panels, energy storage devices, and power grids to achieve stable power supply for household loads. Among them, the on-grid and off-grid controller is connected between the inverter and the power grid. The household load may include a first load and a second load. The first power-taking port for connecting to the first load in the on-grid and off-grid controller is directly connected to the inverter-side port for connecting to the AC side of the inverter. The first load can be powered by the power grid or the inverter. The second power-taking port for connecting to the second load in the on-grid and off-grid controller is directly connected to the grid-side port for connecting to the power grid, and the second load is powered by the power grid. The on-grid and off-grid controller includes a control chip and a relay. The control chip mainly realizes the on-grid and off-grid switching function of the inverter by controlling the closing and opening of the relay.

[0003] The grid-connected and off-grid controller is a medium for connecting the inverter and the grid, and is also an important carrier of the power cable. The inverter, various loads, and the grid are all connected to the grid-connected and off-grid controller through power cables. Since the grid-connected and off-grid controllers are all AC wiring ports, the port appearance, cable specifications, and colors are the same or similar. Although wiring labels are set on the grid-connected and off-grid controllers, it is still inevitable that the cables are misconnected during installation. For example: the cable output by the inverter is connected to the grid-side port or the second power-taking port of the grid-connected and off-grid controller, and the grid is connected to the inverter-side port or the first power-taking port of the grid-connected and off-grid controller. When the power cables are misconnected, the backup power system cannot operate normally, and it may also damage the equipment and even affect personal safety. Summary of the invention

[0004] The present application provides a backup power system and a power wiring detection method thereof, which are used to detect the problem of wrong connection of power cables in the backup power system.

[0005] In a first aspect, the present application provides a backup power system, including: an inverter and a grid-connected and off-grid controller. The grid-connected and off-grid controller includes: an inverter side port and a grid side port, the inverter side port is used to connect to the AC side of the inverter, and the grid side port is used to connect to the power grid. The grid-connected and off-grid controller includes: a switch circuit and a control circuit, the switch circuit is connected between the grid side port and the inverter side port. The control circuit is used to: disconnect the switch circuit and start wiring detection.

[0006] When the control circuit of the on-grid and off-grid controller detects that there is voltage only on the inverter side port or the grid side port, that is, when the grid side port voltage is less than the first threshold, it can be determined whether there is a wiring abnormality based on the inverter side port voltage, the output voltage of the inverter and the operating state of the inverter. Specifically, when the control circuit of the on-grid and off-grid controller determines that: the inverter side port voltage is greater than the first threshold, the inverter output voltage is less than the first threshold, and the inverter is in the shutdown or startup process, that is, there is voltage on the inverter side port, the inverter has no output voltage and is in a non-operating state (including shutdown or startup), it means that the cable of the power grid is connected to the inverter side port or the first power port of the on-grid and off-grid controller, and it is necessary to report the abnormal wiring fault of the grid side port. On the contrary, if the control circuit determines that any of the above items is not met, it is considered that the system wiring is normal, the detection is completed, and the backup power system operates normally.

[0007] When the control circuit of the on-grid controller detects that there is voltage on both the inverter side port and the grid side port, that is, when the voltage on the inverter side port is greater than the first threshold and the voltage on the grid side port is greater than the first threshold, a disturbance instruction is sent to the inverter to make the inverter adjust the output voltage according to the disturbance instruction. If the control circuit determines that the voltage on the grid side port changes with the output voltage of the inverter, it means that the output cable of the inverter is connected to the grid side port or the second power port, and it is necessary to report an abnormal wiring fault on the inverter side port. On the contrary, if the control circuit determines that the voltage on the grid side port does not change with the output voltage of the inverter, it is considered that the system wiring is normal, the detection is completed, and the backup power system operates normally.

[0008] The above detection method can automatically detect whether there is any abnormality in the wiring during the operation of the backup power system, without the need for manual intervention to check the wiring for a single power supply mode. In addition, the detection can be completed by relying on the voltage control and sampling unit inside the backup power system, without adding additional detection components, saving costs, simple logic, fast speed, and accurate detection.

[0009] In some embodiments of the present application, after receiving the disturbance instruction, the inverter disturbs the output voltage of the inverter in a small amplitude range, which can be implemented in the following way: the inverter first controls the output voltage to be the first amplitude for the first duration according to the disturbance instruction, and the first amplitude can be greater than the grid rated voltage amplitude, and then the inverter controls the output voltage to be the second amplitude for the second duration, and the second amplitude can be less than the grid rated voltage amplitude. The first duration and the second duration can take the same value or different values. In addition, the inverter can also control the output voltage to repeat multiple groups of the above operations. Accordingly, the control circuit determines that the grid-side port voltage changes with the output voltage of the inverter, which can be implemented in the following way: the grid-side port voltage is judged to be the third amplitude for the third duration, and then the grid-side port voltage is the fourth amplitude for the fourth duration, and the abnormal connection fault of the inverter side port is reported. The third amplitude is greater than the grid rated voltage amplitude and less than the first amplitude, and the fourth amplitude is less than the grid rated voltage amplitude and greater than the second amplitude. The third duration is less than the first duration, and the fourth duration is less than the second duration.

[0010] In other embodiments of the present application, after receiving the disturbance instruction, the inverter disturbs the output voltage of the inverter within a small amplitude range, which can be specifically implemented in the following manner: the inverter first controls the output voltage to be the second amplitude for the first duration according to the disturbance instruction, and then controls the output voltage to be the first amplitude for the second duration. Correspondingly, the control circuit determines that the grid-side port voltage follows the output voltage change of the inverter, which can be specifically implemented in the following manner: the grid-side port voltage is determined to be the fourth amplitude for the third duration, and then the grid-side port voltage is the third amplitude for the fourth duration, and an abnormal inverter-side port wiring fault is reported.

[0011] Exemplarily, the first amplitude is (1+k2)Un, k2 is a coefficient, and takes values ​​in the range of 0-1, for example, it can take a value of 0.05, and the first duration t1 can take a value of 3 seconds. The second amplitude is (1-k3)Un, k3 is a coefficient, and takes values ​​in the range of 0-1, for example, it can take a value of 0.05, and the second duration t2 can take a value of 3 seconds. The first duration and the second duration can take the same value or different values. The third amplitude is (1+k4)Un, k4 is a coefficient, and takes values ​​in the range of 0-1, k4 is slightly smaller than k2, for example, it can take a value of 0.03. The fourth amplitude is (1-k5)Un, k5 is a coefficient, and takes values ​​in the range of 0-1, k5 is slightly smaller than k3, for example, it can take a value of 0.03. The third duration is smaller than the first duration, and the fourth duration is smaller than the second duration.

[0012] In some embodiments of the present application, the control circuit is also used to: after reporting a wiring abnormality fault, control the on-grid and off-grid controller to shut down and send a shutdown command to the inverter.

[0013] In some embodiments of the present application, the system controller is further included. The system controller is used to forward the disturbance instruction sent by the control circuit to the inverter, and forward the output voltage and operating status sent by the inverter to the control circuit, and the operating status includes grid-connected operation, off-grid operation, shutdown and startup.

[0014] In some embodiments of the present application, the on-grid and off-grid controller further includes: a first power-taking port and a second power-taking port; the first power-taking port is used to connect to the first load, and the second power-taking port is used to connect to the second load. The first power-taking port is connected to the inverter side port, and the second power-taking port is connected to the grid side port.

[0015] In some embodiments of the present application, the switch circuit includes: a first relay and a second relay connected in series; the first relay is connected to the inverter side port, and the second relay is connected to the grid side port.

[0016] In the second aspect, the present application provides a power wiring detection method for a backup power system, comprising the following steps: disconnecting the switch circuit connected between the grid-side port and the inverter-side port in the on-grid and off-grid controller; the inverter-side port is used to connect to the AC side of the inverter, and the grid-side port is used to connect to the power grid. When the voltage of the inverter-side port is greater than a first threshold and the voltage of the grid-side port is greater than the first threshold, a disturbance instruction is sent to the inverter so that the inverter adjusts the output voltage according to the disturbance instruction. If the grid-side port voltage changes with the output voltage of the inverter, an abnormal wiring fault of the inverter-side port is reported. When the grid-side port voltage is less than the first threshold, if the inverter-side port voltage is greater than the first threshold, the output voltage of the inverter is less than the first threshold, and the inverter is in the process of shutting down or starting up, an abnormal wiring fault of the grid-side port is reported.

[0017] In some embodiments of the present application, the inverter adjusts the output voltage according to the disturbance instruction, which may specifically include: according to the disturbance instruction, controlling the output voltage to be a first amplitude for a first duration, controlling the output voltage to be a second amplitude for a second duration, the first amplitude being greater than the grid rated voltage amplitude, and the second amplitude being less than the grid rated voltage amplitude. If the grid-side port voltage changes with the output voltage of the inverter, it may specifically include: if the grid-side port voltage is a third amplitude for a third duration, and then the grid-side port voltage is a fourth amplitude for a fourth duration, reporting an abnormal connection fault of the inverter-side port; the third amplitude is greater than the grid rated voltage amplitude and less than the first amplitude, the fourth amplitude is less than the grid rated voltage amplitude and greater than the second amplitude, the third duration is less than the first duration, and the fourth duration is less than the second duration.

[0018] In other embodiments of the present application, the inverter adjusts the output voltage according to the disturbance instruction, which may specifically include: according to the disturbance instruction, controlling the output voltage to be the second amplitude for the first duration, controlling the output voltage to be the first amplitude for the second duration, the first amplitude is greater than the grid rated voltage amplitude, and the second amplitude is less than the grid rated voltage amplitude. If the grid-side port voltage changes with the output voltage of the inverter, it may specifically include: if the grid-side port voltage is the fourth amplitude for the third duration, and then the grid-side port voltage is the third amplitude for the fourth duration, reporting an abnormal connection fault of the inverter-side port; the third amplitude is greater than the grid rated voltage amplitude and less than the first amplitude, the fourth amplitude is less than the grid rated voltage amplitude and greater than the second amplitude, the third duration is less than the first duration, and the fourth duration is less than the second duration.

[0019] Exemplarily, the first amplitude is (1+k2)Un, k2 is a coefficient, and takes values ​​in the range of 0-1, for example, it can take a value of 0.05, and the first duration t1 can take a value of 3 seconds. The second amplitude is (1-k3)Un, k3 is a coefficient, and takes values ​​in the range of 0-1, for example, it can take a value of 0.05, and the second duration t2 can take a value of 3 seconds. The first duration and the second duration can take the same value or different values. The third amplitude is (1+k4)Un, k4 is a coefficient, and takes values ​​in the range of 0-1, k4 is slightly smaller than k2, for example, it can take a value of 0.03. The fourth amplitude is (1-k5)Un, k5 is a coefficient, and takes values ​​in the range of 0-1, k5 is slightly smaller than k3, for example, it can take a value of 0.03. The third duration is smaller than the first duration, and the fourth duration is smaller than the second duration.

[0020] In some embodiments of the present application, after reporting the abnormal wiring fault, the on-grid and off-grid controller and the inverter can also be controlled to shut down. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the structure of the backup power system;

[0022] Figure 2 A schematic diagram of the structure of the backup power system provided in the embodiment of the present application;

[0023] Figure 3 A schematic diagram of the circuit structure of a single-phase on-grid and off-grid controller provided in an embodiment of the present application;

[0024] Figure 4 A schematic flow chart of a power connection detection method for a backup power system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as being limited to the embodiments described herein; on the contrary, these embodiments are provided to make the present application more comprehensive and complete, and to fully convey the concepts of the example embodiments to those skilled in the art. The same figure marks in the figures represent the same or similar structures, and thus their repeated descriptions will be omitted. The words expressing position and direction described in this application are all explained using the accompanying drawings as examples, but changes may be made as needed, and all changes are included in the scope of protection of this application. The drawings of this application are only used to illustrate the relative position relationship and do not represent the true proportions.

[0026] It should be noted that specific details are described in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in a variety of other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present application. Therefore, the present application is not limited to the specific implementation methods disclosed below. The subsequent description of the specification is a preferred implementation method for implementing the present application, but the description is for the purpose of illustrating the general principles of the present application and is not intended to limit the scope of the present application. The scope of protection of the present application shall be determined by the definition of the attached claims.

[0027] In order to facilitate understanding of the embodiments of the present application, the relevant technologies involved in the embodiments of the present application are first introduced below.

[0028] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to be used as limitations on the present application. As used in the specification and appended claims of the present application, the singular expressions "one", "a kind of" and "the" are intended to also include expressions such as "one or more", unless there is a clear indication to the contrary in the context. It should also be understood that in the following embodiments of the present application, "at least one" refers to one, two or more than two.

[0029] References to "one embodiment" and the like described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the phrases "in one embodiment", "in some embodiments", "in other embodiments", etc. that appear at different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0030] Reference Figure 1The backup power system mainly includes: an inverter and an on-grid and off-grid controller. The on-grid and off-grid controller is connected between the inverter and the power grid. The inverter is used to convert the direct current provided by the photovoltaic module or the energy storage device into alternating current. The on-grid and off-grid controller includes: a first power supply port, a second power supply port, an inverter side port and a grid side port. The first power supply port is directly connected to the inverter side port, the second power supply port is directly connected to the grid side port, the inverter side port is connected to the AC side of the inverter, and the grid side port is used to connect to the power grid. Multiple inverters can be set in the backup power system. Accordingly, the on-grid and off-grid controller can be set with an inverter side port that is connected to the AC side of each inverter in a one-to-one correspondence. The household load connected to the on-grid and off-grid controller includes a first load and a second load. The first power supply port is used to connect to the first load, and the second power supply port is used to connect to the second load. The first load can be powered by the power grid or the inverter, and the second load can be powered by the power grid.

[0031] The on-grid and off-grid controller includes a control chip and a relay. The control chip mainly realizes the on-grid and off-grid switching function of the inverter by controlling the closing and opening of the relay. When the grid is normal, the control chip controls the relay to close, and the backup power system runs on the grid to supply power to the first load; when the grid loses power, the control chip controls the relay to open, the inverter runs off-grid, and supplies power to the first load, thereby ensuring that the first load can always operate normally.

[0032] Since the on-grid and off-grid controllers are all AC wiring ports, the port shapes, cable specifications, and colors are the same or similar. Although there are wiring labels on the on-grid and off-grid controllers, it is still inevitable that the cables are misconnected during installation. For example: the cable output by the inverter is connected to the grid-side port or the second power-drawing port of the on-grid and off-grid controller, and the grid is connected to the inverter-side port or the first power-drawing port of the on-grid and off-grid controller. When there is a situation where the power cables are misconnected, the backup power system cannot operate normally, and it may also damage the equipment and even affect personal safety.

[0033] For the problem of misconnection of power cables in the backup power system, the current technical solutions for wiring detection are mainly as follows: 1) Each wiring is checked one by one through a single power supply, and whether the wiring is normal is judged based on the voltage sampling results after power supply. For example, the inverter is controlled to stop running and all relays in the on-grid and off-grid controller are in the disconnected state. The backup power system is powered only by the power grid. The voltage of each port in the on-grid and off-grid controller is collected and compared with the preset voltage to determine whether the wiring is normal. Checking each wiring one by one through a single power supply requires manual intervention, long detection time, and low efficiency. 2) The actual wiring image is collected through an image acquisition device and compared with the standard wiring image to determine whether there is a misconnection of the power cable. The image comparison method is only applicable to scenarios where the wiring ports are inconsistent. When the size and color of the wiring ports and cables inside the device are consistent, they cannot be correctly identified.

[0034] Based on this, in order to solve the problem that manual intervention is required to ensure the wiring status of the detection cable of a single power supply, resulting in long detection time and low efficiency, and the problem that the wrong connection cannot be correctly identified through image comparison when the wiring ports are consistent, the embodiment of the present application provides a backup power system and its power wiring detection method, which can quickly detect the problem of wrong connection of power cables in the backup power system.

[0035] Reference Figure 2 , the backup power system provided in the embodiment of the present application includes an inverter and an on-grid and off-grid controller. The backup power system may also include a system controller, which is mainly used for system communication transmission, power scheduling, information reporting and other functions. Generally, the system controller is connected to the inverter and the on-grid and off-grid controller through an RS485 communication cable. The inverter is connected between the DC source and the on-grid and off-grid controller. The DC side of the inverter is used to connect to the DC source. The DC source can specifically be a photovoltaic module. The DC source can also be an energy storage device. The AC side of the inverter is connected to the inverter side of the on-grid and off-grid controller. The inverter is used to convert the DC power provided by the photovoltaic module or the energy storage device into AC power. The inverter may specifically include an inverter circuit, and may also include a DC conversion circuit. The DC conversion circuit is used to convert the DC power provided by the photovoltaic module into power. The inverter circuit is used to convert the DC power provided by the DC conversion circuit or the DC power provided by the energy storage device into AC power. The on-grid and off-grid controller may specifically include a switching circuit and a control circuit ( Figure 2 The grid side of the switch circuit is used to connect to the grid, and the inverter side of the switch circuit is connected to the AC side of the inverter. In order to meet the power safety requirements, the switch circuit generally includes a two-stage switch, namely a first relay T1 and a second relay T2 connected in series.

[0036] Reference Figure 3 The grid-connected and off-grid controller includes two ports, specifically: an inverter side port and a grid side port. The inverter side port is used to connect to the AC side of the inverter, and the grid side port is used to connect to the power grid. The switch circuit is connected between the grid side port and the inverter side port. Specifically, the first relay T1 is connected to the inverter side port, and the second relay T2 is connected to the grid side port. Optionally, the grid-connected and off-grid controller may also include: a first power supply port and a second power supply port. The first power supply port is connected to the inverter side port, and the second power supply port is connected to the grid side port. The first power supply port is used to connect to the first load, and the second power supply port is used to connect to the second load. Multiple inverters can be set in the backup power system. Accordingly, the grid-connected and off-grid controller can be set with an inverter side port for one-to-one connection with the AC side of each inverter. Refer to Figure 3The grid-connected and off-grid controller provided in the present application may adopt a single-phase grid-connected and off-grid controller. In addition, the grid-connected and off-grid controller may also include an NPE relay T3 connected between the neutral line N and the ground line PE, and a bypass switch T4 connected between the inverter side port and the grid side port.

[0037] In the present application, when the grid-connected and off-grid controller is powered by an inverter or a power grid, and the backup power system needs to perform wiring detection, the control circuit of the grid-connected and off-grid controller first disconnects the switch circuit in the grid-connected and off-grid controller to disconnect the connection between the inverter side port and the grid side port inside the grid-connected and off-grid controller, so that the voltage of the inverter side port changes according to the voltage of the connecting cable, and the voltage of the grid side port changes according to the voltage of the connecting cable, and the wiring detection is started to detect the voltages of the inverter side port and the grid side port to make corresponding logical judgments.

[0038] When the control circuit of the on-grid and off-grid controller detects that only the inverter side port or the grid side port has voltage, that is, when the grid side port voltage is less than the first threshold, it can be determined whether there is a wiring abnormality based on the inverter side port voltage, the inverter output voltage and the inverter operating state. Among them, the inverter side port voltage can be obtained by sampling the on-grid and off-grid controller itself, and the inverter output voltage and the inverter operating state are sampled by the inverter and transmitted to the on-grid and off-grid controller through the RS485 communication cable and the system controller. The inverter operating state includes off-grid operation, grid-connected operation, shutdown or startup, and the inverter is in a non-operating state, that is, in the startup process or shutdown, etc. When the control circuit of the on-grid and off-grid controller determines that it satisfies at the same time: the inverter side port voltage is greater than the first threshold, the inverter output voltage is less than the first threshold, and the inverter is in the shutdown or startup process, that is, there is voltage on the inverter side port, the inverter has no output voltage and is in a non-operating state, it means that the cable of the power grid is connected to the inverter side port or the first power-taking port of the on-grid and off-grid controller, and it is necessary to report the abnormal wiring fault of the grid side port. Furthermore, the control circuit can also control the on-grid and off-grid controller to shut down, and send a shutdown command to the inverter through the RS485 communication cable and the system controller to shut down the inverter. On the contrary, if the control circuit determines that any of the above items is not satisfied, it is considered that the system wiring is normal, the detection is completed, and the backup power system operates normally.

[0039] When the control circuit of the grid-connected and off-grid controller detects that both the inverter side port and the grid side port have voltage, that is, when the voltage of the inverter side port is greater than the first threshold and the voltage of the grid side port is greater than the first threshold, a disturbance instruction is sent to the inverter so that the inverter adjusts the output voltage according to the disturbance instruction. Exemplarily, the control circuit can transmit the disturbance instruction to the grid-connected and off-grid controller through the RS485 communication cable and the system controller, and the inverter disturbs the output voltage of the inverter in a small amplitude range after receiving the disturbance instruction. When the control circuit determines that the grid side port voltage changes with the output voltage of the inverter, it means that the output cable of the inverter is connected to the grid side port or the second power port, and it is necessary to report the abnormal wiring fault of the inverter side port. Further, the control circuit can also control the grid-connected and off-grid controller to shut down, and send a shutdown instruction to the inverter through the RS485 communication cable and the system controller to shut down the inverter. On the contrary, if the control circuit determines that the grid side port voltage does not change with the output voltage of the inverter, it is considered that the system wiring is normal, the detection is completed, and the backup power system operates normally.

[0040] The above detection method can automatically detect whether there is any abnormality in the wiring during the operation of the backup power system, without the need for manual intervention to check the wiring for a single power supply mode. In addition, the detection can be completed by relying on the voltage control and sampling unit inside the backup power system, without adding additional detection components, saving costs, simple logic, fast speed, and accurate detection.

[0041] In some embodiments of the present application, after receiving the disturbance instruction, the inverter disturbs the output voltage of the inverter within a small amplitude range, which can be specifically implemented in the following manner: the inverter first controls the output voltage to be a first amplitude for a first duration according to the disturbance instruction, and the first amplitude can be greater than the rated voltage amplitude of the power grid Un, for example, the first amplitude is (1+k2)Un, k2 is a coefficient, for example, it can take a value of 0.05, and the first duration t1 can take a value of 3 seconds. Then the inverter controls the output voltage to be a second amplitude for a second duration, and the second amplitude can be less than the rated voltage amplitude of the power grid, for example, the second amplitude is (1-k3)Un, k3 is a coefficient, for example, it can take a value of 0.05, and the second duration t2 can take a value of 3 seconds. The first duration t1 and the second duration t2 can take the same value or different values. In addition, the inverter can also control the output voltage to repeat multiple groups of the above operations.

[0042] Correspondingly, the control circuit determines that the grid-side port voltage follows the output voltage change of the inverter, which can be specifically implemented in the following manner: determine that the grid-side port voltage is the third amplitude for the third duration, and then the grid-side port voltage is the fourth amplitude for the fourth duration, and report the abnormal connection fault of the inverter side port. The third amplitude is greater than the grid rated voltage amplitude and less than the first amplitude, for example, the third amplitude is (1+k4)Un, k4 is a coefficient slightly less than k2, for example, it can take a value of 0.03. The fourth amplitude is less than the grid rated voltage amplitude and greater than the second amplitude, for example, the fourth amplitude is (1-k5)Un, k5 is a coefficient slightly less than k3, for example, it can take a value of 0.03. The third duration t3 is less than the first duration t1, for example, it can take a value of 2 seconds, and the fourth duration t4 is less than the second duration t2, for example, it can take a value of 2 seconds.

[0043] Alternatively, in other embodiments of the present application, after receiving a disturbance instruction, the inverter disturbs the output voltage of the inverter within a small amplitude range, which can be specifically implemented in the following manner: the inverter first controls the output voltage to be a second amplitude for a first duration according to the disturbance instruction, and then the inverter controls the output voltage to be a first amplitude for a second duration.

[0044] Correspondingly, the control circuit determines that the grid-side port voltage follows the output voltage change of the inverter, which can be specifically implemented in the following manner: determine that the grid-side port voltage is the fourth amplitude for a third period of time, and then the grid-side port voltage is the third amplitude for a fourth period of time, and report an abnormal wiring fault at the inverter side port.

[0045] Based on the same inventive concept, the embodiment of the present application also provides a power wiring detection method, comprising the following steps:

[0046] Disconnect the switch circuit connected between the grid-side port and the inverter-side port in the on-off-grid controller; the inverter-side port is used to connect to the AC side of the inverter, and the grid-side port is used to connect to the power grid.

[0047] When the inverter side port voltage is greater than the first threshold and the grid side port voltage is greater than the first threshold, a disturbance instruction is sent to the inverter so that the inverter adjusts the output voltage according to the disturbance instruction. If the grid side port voltage changes with the output voltage of the inverter, an abnormal connection fault of the inverter side port is reported.

[0048] When the grid-side port voltage is less than the first threshold, if the inverter-side port voltage is greater than the first threshold, the output voltage of the inverter is less than the first threshold, and the inverter is in the shutdown or startup process, a grid-side port wiring abnormality fault is reported.

[0049] In some embodiments of the present application, the inverter adjusts the output voltage according to the disturbance instruction, which may specifically include: according to the disturbance instruction, controlling the output voltage to a first amplitude for a first duration, controlling the output voltage to a second amplitude for a second duration, the first amplitude being greater than the rated voltage amplitude of the grid, and the second amplitude being less than the rated voltage amplitude of the grid.

[0050] If the grid-side port voltage changes with the output voltage of the inverter, it may specifically include: if the grid-side port voltage is a third amplitude for a third period of time, and the grid-side port voltage is a fourth amplitude for a fourth period of time, an abnormal wiring fault of the inverter side port is reported; the third amplitude is greater than the grid rated voltage amplitude and less than the first amplitude, the fourth amplitude is less than the grid rated voltage amplitude and greater than the second amplitude, the third duration is less than the first duration, and the fourth duration is less than the second duration.

[0051] Alternatively, in other embodiments of the present application, the inverter adjusts the output voltage according to the disturbance instruction, which may specifically include: according to the disturbance instruction, controlling the output voltage to be a second amplitude for a first duration, controlling the output voltage to be a first amplitude for a second duration, the first amplitude being greater than the rated voltage amplitude of the grid, and the second amplitude being less than the rated voltage amplitude of the grid.

[0052] If the grid-side port voltage changes with the output voltage of the inverter, it may specifically include: if the grid-side port voltage is the fourth amplitude for the third time period, and the grid-side port voltage is the third amplitude for the fourth time period, an abnormal connection fault of the inverter side port is reported; the third amplitude is greater than the grid rated voltage amplitude and less than the first amplitude, the fourth amplitude is less than the grid rated voltage amplitude and greater than the second amplitude, the third time period is less than the first time period, and the fourth time period is less than the second time period.

[0053] In some embodiments of the present application, after reporting the abnormal wiring fault, the on-grid and off-grid controller and the inverter can also be controlled to shut down.

[0054] The wiring detection method provided by the present application is described in detail below through specific embodiments.

[0055] Reference Figure 4 The present application proposes a power wiring detection method for the problem of misconnection of power cables in a backup power system, comprising the following steps:

[0056] S1. When the on-grid and off-grid controller is powered by an inverter or a power grid and the backup power system needs to perform wiring detection, the control circuit of the on-grid and off-grid controller disconnects the switch circuit in the on-grid and off-grid controller and starts the wiring detection.

[0057] S2. Determine whether the inverter port voltage is greater than a first threshold and whether the grid port voltage is greater than a first threshold. Specifically, the first threshold may be k1Un, where Un is the grid rated voltage amplitude and k1 is a coefficient, which may be 0.5, for example.

[0058] S3. When it is determined that the inverter-side port voltage is greater than the first threshold and the grid-side port voltage is greater than the first threshold, the grid-connecting and off-grid controller sends a disturbance instruction to the inverter.

[0059] S4. The inverter adjusts the output voltage according to the disturbance command. The starting time of the disturbance command is set to t0. After receiving the disturbance command, the inverter starts to perturb the output voltage in a small amplitude range. Exemplarily, the inverter first controls the output voltage to be a first amplitude for a first duration. The first amplitude can be greater than the rated voltage amplitude of the power grid. For example, the first amplitude is (1+k2)Un, k2 is a coefficient, for example, it can be 0.05, and the first duration t1 can be 3 seconds. Then the inverter controls the output voltage to be a second amplitude for a second duration. The second amplitude can be less than the rated voltage amplitude of the power grid. For example, the second amplitude is (1-k3)Un, k3 is a coefficient, for example, it can be 0.05, and the second duration t2 can be 3 seconds. The first duration t1 and the second duration t2 can take the same value or different values. In addition, the inverter can also control the output voltage to repeat multiple groups of the above operations.

[0060] S5. The on-grid and off-grid controller determines whether the grid-side port voltage changes with the output voltage of the inverter. Exemplarily, within the [t0, tx] time window, it is determined whether the grid-side port voltage is the third amplitude for the third duration, and then the grid-side port voltage is the fourth amplitude for the fourth duration. The third amplitude is greater than the grid rated voltage amplitude and less than the first amplitude, for example, the third amplitude is (1+k4)Un, k4 is a coefficient slightly less than k2, for example, it can take a value of 0.03. The fourth amplitude is less than the grid rated voltage amplitude and greater than the second amplitude, for example, the fourth amplitude is (1-k5)Un, k5 is a coefficient slightly less than k3, for example, it can take a value of 0.03. The third duration t3 is less than the first duration t1, for example, it can take a value of 2 seconds, the fourth duration t4 is less than the second duration t2, for example, it can take a value of 2 seconds, and tx generally takes a value of 8 to 12 seconds.

[0061] S6. When the control circuit determines that the grid-side port voltage changes with the output voltage of the inverter, it means that the output cable of the inverter is connected to the grid-side port or the second power port, and an abnormal connection fault of the inverter-side port is reported, and the backup power system is shut down.

[0062] S7. When the control circuit determines that the grid-side port voltage does not change with the output voltage of the inverter, it is considered that the backup power system wiring is normal, the detection is completed, and the backup power system operates normally.

[0063] S8. When the grid-side port voltage is less than the first threshold, the control circuit of the grid-connected and off-grid controller determines whether the following conditions are met at the same time: the inverter-side port voltage is greater than the first threshold, the inverter output voltage is less than the first threshold, and the inverter is in the shutdown or startup process.

[0064] If all the above conditions are met at the same time, it means that the power grid cable is connected to the inverter port or the first power port of the on-grid and off-grid controller, and the abnormal connection fault of the grid port needs to be reported. On the contrary, if the control circuit determines that any of the above conditions is not met, it is considered that the system connection is normal, the detection is completed, and the backup power system is operating normally.

[0065] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A backup power system, characterized in that: include: Inverter and on-grid and off-grid controller; The on-grid and off-grid controller comprises: an inverter side port and a grid side port; the inverter side port is used to connect to the AC side of the inverter, and the grid side port is used to connect to the grid; The on-grid and off-grid controller comprises: a switch circuit and a control circuit, wherein the switch circuit is connected between the grid-side port and the inverter-side port; The control circuit is used to: disconnect the switch circuit; When the inverter-side port voltage is greater than a first threshold and the grid-side port voltage is greater than the first threshold, a disturbance instruction is sent to the inverter so that the inverter adjusts the output voltage according to the disturbance instruction, and if the grid-side port voltage changes with the output voltage of the inverter, an abnormal connection fault of the inverter-side port is reported; When the grid-side port voltage is less than the first threshold, if the inverter-side port voltage is greater than the first threshold, the output voltage of the inverter is less than the first threshold, and the inverter is in the shutdown or startup process, the grid-side port wiring abnormality fault is reported.

2. The backup power system according to claim 1, characterized in that: The inverter is used to: according to the disturbance instruction, control the output voltage to be a first amplitude for a first duration, and then control the output voltage to be a second amplitude for a second duration, wherein the first amplitude is greater than the rated voltage amplitude of the power grid, and the second amplitude is less than the rated voltage amplitude of the power grid; The control circuit is used for: if the grid-side port voltage is a third amplitude for a third time period, and then the grid-side port voltage is a fourth amplitude for a fourth time period, reporting an abnormal wiring fault at the inverter side port; the third amplitude is greater than the grid rated voltage amplitude and less than the first amplitude, the fourth amplitude is less than the grid rated voltage amplitude and greater than the second amplitude, the third time period is less than the first time period, and the fourth time period is less than the second time period.

3. The backup power system according to claim 1, characterized in that: The inverter is used to: according to the disturbance instruction, control the output voltage to be a second amplitude for a first duration, and then control the output voltage to be a first amplitude for a second duration, wherein the first amplitude is greater than the rated voltage amplitude of the power grid, and the second amplitude is less than the rated voltage amplitude of the power grid; The control circuit is used to: if the grid-side port voltage is the fourth amplitude for a third time period, and then the grid-side port voltage is the third amplitude for a fourth time period, report the abnormal wiring fault of the inverter side port, the third amplitude is greater than the grid rated voltage amplitude and less than the first amplitude, the fourth amplitude is less than the grid rated voltage amplitude and greater than the second amplitude, the third time period is less than the first time period, and the fourth time period is less than the second time period.

4. The backup power system according to claim 2 or 3, characterized in that: The first amplitude is (1+k2)Un, the second amplitude is (1-k3)Un, the third amplitude is (1+k4)Un, and the fourth amplitude is (1-k5)Un; Among them, Un is the rated voltage amplitude of the power grid, k2, k3, k4 and k5 are between 0 and 1, k5 is smaller than k3, and k4 is smaller than k2.

5. The backup power system according to any one of claims 2 to 4, characterized in that: The third duration is shorter than the first duration, and the fourth duration is shorter than the second duration.

6. The backup power system according to any one of claims 1 to 5, characterized in that: The control circuit is also used to: after reporting an abnormal wiring fault, control the on-grid and off-grid controller to shut down, and send a shutdown instruction to the inverter.

7. The backup power system according to any one of claims 1 to 6, characterized in that: Also includes: System controller; The system controller is used to: forward the disturbance instruction sent by the control circuit to the inverter, and forward the output voltage and operating status sent by the inverter to the control circuit, wherein the operating status includes grid-connected operation, off-grid operation, shutdown and startup.

8. The backup power system according to any one of claims 1 to 6, characterized in that: The on-grid and off-grid controller further includes: a first power-taking port and a second power-taking port; the first power-taking port is used to connect to a first load, and the second power-taking port is used to connect to a second load; The first power-taking port is connected to the inverter-side port, and the second power-taking port is connected to the grid-side port.

9. The backup power system according to any one of claims 1 to 7, characterized in that: The switch circuit includes: a first relay and a second relay connected in series; the first relay is connected to the inverter side port, and the second relay is connected to the grid side port.

10. A power wiring detection method for a backup power system, characterized in that: include: Disconnecting the switch circuit connected between the grid-side port and the inverter-side port in the on-grid and off-grid controller; The inverter side port is used to connect to the AC side of the inverter, and the grid side port is used to connect to the grid; When the inverter-side port voltage is greater than a first threshold and the grid-side port voltage is greater than the first threshold, a disturbance instruction is sent to the inverter so that the inverter adjusts the output voltage according to the disturbance instruction, and if the grid-side port voltage changes with the output voltage of the inverter, an abnormal connection fault of the inverter-side port is reported; When the grid-side port voltage is less than the first threshold, if the inverter-side port voltage is greater than the first threshold, the output voltage of the inverter is less than the first threshold, and the inverter is in the shutdown or startup process, the grid-side port wiring abnormality fault is reported.

11. The power wiring detection method according to claim 10, characterized in that: The inverter adjusts the output voltage according to the disturbance instruction, including: According to the disturbance instruction, the output voltage is controlled to be a first amplitude for a first duration, and then the output voltage is controlled to be a second amplitude for a second duration, wherein the first amplitude is greater than the rated voltage amplitude of the power grid, and the second amplitude is less than the rated voltage amplitude of the power grid; If the grid-side port voltage changes with the output voltage of the inverter, it includes: If the grid-side port voltage is the third amplitude for the third time period, and then the grid-side port voltage is the fourth amplitude for the fourth time period, an abnormal wiring fault of the inverter side port is reported; the third amplitude is greater than the grid rated voltage amplitude and less than the first amplitude, the fourth amplitude is less than the grid rated voltage amplitude and greater than the second amplitude, the third time period is less than the first time period, and the fourth time period is less than the second time period.

12. The power wiring detection method according to claim 10, characterized in that: The inverter adjusts the output voltage according to the disturbance instruction, including: according to the disturbance instruction, controlling the output voltage to be a second amplitude for a first duration, controlling the output voltage to be a first amplitude for a second duration, wherein the first amplitude is greater than the rated voltage amplitude of the power grid, and the second amplitude is less than the rated voltage amplitude of the power grid; If the grid-side port voltage changes with the output voltage of the inverter, including: if the grid-side port voltage is a fourth amplitude for a third time period, the grid-side port voltage is a third amplitude for a fourth time period, and an abnormal connection fault of the inverter side port is reported; the third amplitude is greater than the grid rated voltage amplitude and less than the first amplitude, the fourth amplitude is less than the grid rated voltage amplitude and greater than the second amplitude, the third time period is less than the first time period, and the fourth time period is less than the second time period.

13. The power wiring detection method according to claim 11 or 12, characterized in that: The first amplitude is (1+k2)Un, the second amplitude is (1-k3)Un, the third amplitude is (1+k4)Un, and the fourth amplitude is (1-k5)Un; Among them, Un is the rated voltage amplitude of the power grid, k2, k3, k4 and k5 are between 0 and 1, k5 is smaller than k3, and k4 is smaller than k2.

14. The power wiring detection method according to any one of claims 11 to 13, characterized in that: The third duration is shorter than the first duration, and the fourth duration is shorter than the second duration.

15. The power wiring detection method according to any one of claims 10 to 14, characterized in that: Also includes: After reporting the abnormal wiring fault, the on-grid and off-grid controller and the inverter are controlled to shut down.

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