Standby power system and closing detection method of manual bypass air switch

Abstract

The invention provides a standby power system and a closing detection method of a manual bypass air switch, and belongs to the technical field of power electronics. In the scheme provided by the invention, on the premise that the grid-connected and off-grid relay in the grid-connected and off-grid controller is switched off, if the control circuit detects that the voltage difference between the two ends of the manual bypass air switch (namely the bypass air switch) is smaller than the second threshold value, the voltage of the inverter side port of the grid-connected and off-grid controller can be determined to be relatively close to the voltage of the power grid side port of the grid-connected and off-grid controller. At the moment, if the control circuit detects that the inverter is in a non-operation state, and the voltage of the inverter side port and the voltage of the power grid side port are both larger than a first threshold value, it can be further determined that the voltage of the inverter side port is provided by the power grid through the closed bypass air switch. Therefore, the control circuit can accurately determine that the bypass air switch is in a closed state and send out an alarm signal. According to the detection method, false detection can be effectively avoided, and it is ensured that the detection accuracy of the closed state of the bypass air switch is high.

Description

Technical Field

[0001] The present application relates to the field of power electronics technology, and in particular to a backup power system and a closure detection method for a manual bypass air switch. Background Art

[0002] The backup power system usually includes an inverter and an on-grid and off-grid controller. Among them, the on-grid and off-grid controller is connected between the inverter and the grid to realize the switching between the on-grid state and the off-grid state. The on-grid and off-grid controller mainly includes an on-grid and off-grid relay and a bypass air switch. In the off-grid state, the on-grid and off-grid relay is disconnected, and the inverter converts the DC power provided by the photovoltaic panel into AC power to supply power to the local load. In the on-grid state, the on-grid and off-grid relay is closed, and the inverter converts the DC power provided by the photovoltaic panel into AC power and transmits it to the grid through the on-grid and off-grid relay. At this time, the local load is powered by the inverter or the grid. When the on-grid and off-grid controller fails, the two ends of the on-grid and off-grid controller can be short-circuited by manually closing the manual bypass air switch so that the grid can supply power to the local load.

[0003] In the off-grid state, if the manual bypass air switch is closed due to misoperation, it will seriously affect the safety and stability of the backup power system. Therefore, it is necessary to detect the closed state of the manual bypass air switch. Usually, the on-grid controller can determine whether the manual bypass air switch is closed by detecting the voltage difference between the two ends of the manual bypass air switch. However, this detection method may have false detection and low accuracy. Summary of the invention

[0004] The present application provides a backup power system and a method for detecting the closure of a manual bypass air switch, which can solve the technical problem of low detection accuracy when detecting whether the manual bypass air switch is closed by using the voltage difference across the two ends of the manual bypass air switch.

[0005] In the first aspect, a backup power system is provided, which includes an inverter and an on-grid and off-grid controller. The inverter side port of the on-grid and off-grid controller is connected to the inverter, and the grid side port is used to connect to the grid. In addition, the on-grid and off-grid controller includes: an on-grid and off-grid relay, a manual bypass air switch and a control circuit. Among them, the on-grid and off-grid relay is connected between the inverter side port and the grid side port, and the manual bypass air switch is connected between the inverter side port and the grid side port. The control circuit is connected to the inverter side port, the grid side port, the inverter and the on-grid and off-grid relay respectively. The inverter is used to send a status indication signal to the control circuit, and the status indication signal is used to indicate that the inverter is in an operating state or a non-operating state. The control circuit is used to detect the voltage of the inverter side port and the voltage of the grid side port. If the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold when the on-grid and off-grid relay is disconnected, the voltage difference between the two ends of the manual bypass air switch is less than the second threshold, and the inverter is in a non-operating state, then an alarm signal is issued. The alarm signal is used to indicate that the manual bypass air switch is in a closed state. The first threshold is greater than the second threshold.

[0006] Under the premise that the on-grid relay is disconnected, if the control circuit detects that the voltage difference between the two ends of the manual bypass air switch is less than the second threshold, it can be determined that the voltage of the inverter side port of the on-grid controller is close to the voltage of the grid side port. At this time, if the control circuit detects that the inverter is in a non-operating state, that is, the inverter does not output voltage to the inverter side port, and the voltages of the inverter side port and the grid side port are both greater than the first threshold, the control circuit can determine that the voltage of the inverter side port is provided by the grid through the closed manual bypass air switch. Thus, the control circuit can accurately determine that the manual bypass air switch is in a closed state. The above detection method can effectively avoid false detection and ensure that the detection accuracy of the closed state of the manual bypass air switch is high.

[0007] It can be understood that if the voltage of the inverter side port or the voltage of the grid side port is less than the first threshold value, that is, the voltage of either side port of the on-grid controller is lower, the control circuit can determine that the manual bypass air switch is not closed. Alternatively, if the voltage difference across the manual bypass air switch is not less than the second threshold value, that is, the voltage of the inverter side port of the on-grid controller and the voltage of the grid side port differ greatly, the control circuit can also determine that the manual bypass air switch is not closed. If the control circuit determines that the manual bypass air switch is not closed, the closing detection process can be terminated, and the off-grid controller operates normally.

[0008] Optionally, the control circuit is used to send an alarm signal if the voltage of the inverter side port and the voltage of the grid side port are both greater than a first threshold, the voltage difference across the manual bypass air switch is less than the second threshold for a first time period, and the inverter is in a non-operating state.

[0009] It can be understood that if the voltage difference across the manual bypass air switch is less than the second threshold value for a first period of time, that is, the voltage difference across the manual bypass air switch is continuously and stably less than the second threshold value, the control circuit can more accurately determine that the manual bypass air switch is in a closed state.

[0010] Optionally, the control circuit is also used to control the grid-connected and off-grid relay to remain in an off state after determining that the manual bypass air switch is closed, and send a shutdown command to the inverter. The inverter is also used to shut down according to the shutdown command. After detecting that the manual bypass air switch is closed, the control circuit instructs the inverter to shut down through a shutdown command, which can effectively ensure the safety of the backup power system. For example, the risk of electric shock can be effectively reduced. Among them, the control circuit controls the grid-connected and off-grid relay to remain in an off state, and the grid-connected and off-grid controller can also be considered to be in a shutdown state.

[0011] Optionally, the inverter side port of the on-grid and off-grid controller is also used to connect a backup load, and the grid side port of the on-grid and off-grid controller is also used to connect a non-backup load. The backup load may refer to an important load in a household load, and the non-backup load may refer to a non-important load in a household load. For example, the backup load may include lighting equipment, and the non-backup load may include smart home appliances. When there is a power outage on the grid side, the backup system runs off-grid, the on-grid and off-grid relay in the on-grid and off-grid controller is disconnected, and the inverter can supply power to the backup load to ensure that the backup load can operate normally.

[0012] Optionally, the first threshold is k1U n , the second threshold is k2U n Among them, U n is the rated voltage of the power grid, k1 is the first coefficient, k2 is the second coefficient. Moreover, the value range of the second coefficient is 0.01 to 0.1, for example, it can be 0.02. The first coefficient is greater than the first coefficient and less than 1, for example, it can be 0.5.

[0013] In a second aspect, another backup power system is provided, which includes an inverter and an on-grid and off-grid controller. The inverter side port of the on-grid and off-grid controller is connected to the inverter, and the grid side port is used to connect to the grid. In addition, the on-grid and off-grid controller includes: an on-grid and off-grid relay, a manual bypass air switch and a control circuit. Among them, the on-grid and off-grid relay is connected between the inverter side port and the grid side port, the manual bypass air switch is connected between the inverter side port and the grid side port, and the control circuit is respectively connected to the inverter side port, the grid side port, the inverter and the on-grid and off-grid relay. The inverter is used to send a status indication signal to the control circuit, and the status indication signal is used to indicate that the inverter is in an operating state or a non-operating state. The control circuit is used to detect the voltage of the inverter side port and the voltage of the grid side port; when the on-grid and off-grid relay is disconnected, if it is detected that the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold, and the inverter is in an operating state, a disturbance instruction is sent to the inverter. The inverter is used to control the effective voltage of its output to be a first voltage and a second voltage in sequence according to the disturbance instruction, and the first voltage and the second voltage are different. That is, the inverter can control the effective voltage of its output to be disturbed within a certain amplitude range according to the disturbance instruction, that is, output the disturbed effective voltage. The control circuit is also used to detect the voltage difference between the two ends of the manual bypass air switch after sending the disturbance instruction, and send an alarm signal if the voltage difference is less than the second threshold. The alarm signal is used to indicate that the manual bypass air switch is in a closed state.

[0014] It is understandable that after the inverter outputs a disturbed effective voltage to the inverter side port of the grid-connected and off-grid controller, the voltage of the inverter side port (i.e., the effective voltage of the inverter side port) will fluctuate within a certain range. At this time, if the control circuit detects that the voltage difference across the manual bypass air switch is less than the second threshold, it can be determined that the voltage of the grid side port can pass through the closed manual bypass air switch and fluctuate with the voltage fluctuation of the inverter side port. Thus, the control circuit can accurately determine that the manual bypass air switch is in a closed state and issue an alarm signal. The above-mentioned closure detection method can effectively avoid false detection and ensure that the detection accuracy of the closed state of the manual bypass air switch is high.

[0015] It can also be understood that after the inverter outputs the disturbance voltage to the inverter-side port of the on-grid controller, if the control circuit detects that the voltage difference across the manual bypass air switch is not less than the second threshold, that is, the voltage of the inverter-side port of the on-grid controller differs greatly from the voltage of the grid-side port, then the control circuit can determine that the manual bypass air switch is not closed. After that, the control circuit can terminate the closing detection process, and the off-grid controller operates normally.

[0016] Optionally, the control circuit is used to send a disturbance command to the inverter when the on-grid and off-grid relay is disconnected, if it is detected that the voltage of the inverter side port and the voltage of the grid side port are both greater than a first threshold, the voltage difference across the manual bypass air switch is less than a second threshold, and the inverter is in operation.

[0017] It is understandable that when the on-grid relay is disconnected, if the control circuit detects that the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold, and the voltage difference across the manual bypass air switch is less than the second threshold, it can be determined that the manual bypass air switch may be in a closed state. Therefore, the control circuit can continue to execute the subsequent closing detection process, that is, send a disturbance instruction to the inverter.

[0018] Optionally, the control circuit is used to send a disturbance command to the inverter when the on-grid and off-grid relay is disconnected, if it is detected that the voltage of the inverter side port and the voltage of the grid side port are both greater than a first threshold, the voltage difference across the manual bypass air switch is less than the second threshold for a first time period, and the inverter is in operation.

[0019] Optionally, the control circuit is used to send an alarm signal if it is detected that the voltage difference between the two ends of the manual bypass air switch is less than the second threshold for a third time period within the second time period after the disturbance instruction is sent. The second time period is greater than the third time period.

[0020] That is, the control circuit can continuously detect the voltage difference across the manual bypass air switch within the detection time window after the disturbance instruction is issued, and the duration of the detection time window is the second duration. If within the detection time window, the voltage difference across the manual bypass air switch is less than the second threshold value for a duration of a third duration, the control circuit can accurately determine that the manual bypass air switch is in a closed state and issue an alarm signal.

[0021] Optionally, the duration of the first voltage is a fourth duration, and the duration of the second voltage is a fifth duration, wherein the third duration is greater than the fourth duration, and greater than the fifth duration.

[0022] Since the inverter can control the effective voltage outputted by it to be continuously the first voltage within the fourth time period after receiving the disturbance instruction, and can control the effective voltage outputted by it to be continuously the second voltage within the fifth time period, it can be known that the effective voltage outputted by the inverter will fluctuate at least within a time period greater than the fourth time period or greater than the fifth time period. Accordingly, if the control circuit detects that the voltage difference across the manual bypass air switch is less than the second threshold value within the third time period (i.e., within a time period greater than the fourth time period and greater than the fifth time period), it can accurately determine that the manual bypass air switch is in a closed state.

[0023] Optionally, the first voltage is (1+k3)U n , the second voltage is (1-k3)U n , where U n is the rated voltage of the power grid, k3 is the third coefficient, and the value range is 0 to 0.2. For example, the third coefficient may be 0.05.

[0024] Optionally, the control circuit is further used to control the grid-connected and off-grid relay to remain in an off state after determining that the manual bypass air switch is closed, and to send a shutdown instruction to the inverter. The inverter is also used to shut down according to the shutdown instruction.

[0025] Optionally, the inverter side port of the on-grid and off-grid controller is also used to connect a backup power load, and the grid side port of the on-grid and off-grid controller is also used to connect a non-backup power load.

[0026] In the third aspect, a method for detecting the closure of a manual bypass air switch is provided, which is applied to the backup power system provided in the first aspect. The method includes: detecting the voltage of the inverter side port of the on-grid controller, the voltage of the grid side port, and the operating state of the inverter; if the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold when the on-grid relay is disconnected, the voltage difference between the two ends of the manual bypass air switch is less than the second threshold, and the inverter is in a non-operating state, an alarm signal is issued. The alarm signal is used to indicate that the manual bypass air switch is in a closed state.

[0027] In a fourth aspect, another method for detecting the closure of a manual bypass air switch is provided, which is applied to the backup power system provided in the second aspect above. The method includes: detecting the voltage of the inverter side port of the on-grid controller, the voltage of the grid side port, and the operating state of the inverter. When the on-grid relay is disconnected, if it is detected that the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold value, and the inverter is in operation, a disturbance instruction is sent to the inverter. According to the disturbance instruction, the inverter controls the effective voltage of its output to be the first voltage and the second voltage, respectively, and the first voltage is different from the second voltage. After sending the disturbance instruction, if it is detected that the voltage difference between the two ends of the manual bypass air switch is less than the second threshold value, an alarm signal is issued, and the alarm signal is used to indicate that the manual bypass air switch is in a closed state.

[0028] In the fifth aspect, a grid-connected and off-grid controller is provided. The inverter side port of the grid-connected and off-grid controller is used to connect the inverter, and the grid side port is used to connect the grid. In addition, the grid-connected and off-grid controller includes: a grid-connected and off-grid relay, a manual bypass air switch and a control circuit. Among them, the grid-connected and off-grid relay is connected between the inverter side port and the grid side port, and the manual bypass air switch is connected between the inverter side port and the grid side port. The control circuit is connected to the inverter side port, the grid side port, the inverter and the grid-connected and off-grid relay respectively. The control circuit is used to detect the voltage of the inverter side port, the voltage of the grid side port and the operating state of the inverter. If the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold value when the grid-connected and off-grid relay is disconnected, the voltage difference between the two ends of the manual bypass air switch is less than the second threshold value, and the inverter is in a non-operating state, then an alarm signal is issued. The alarm signal is used to indicate that the manual bypass air switch is in a closed state.

[0029] In the sixth aspect, another on-grid and off-grid controller is provided. The inverter side port of the on-grid and off-grid controller is connected to the inverter, and the grid side port is used to connect to the grid. In addition, the on-grid and off-grid controller includes: an on-grid and off-grid relay, a manual bypass air switch and a control circuit. Among them, the on-grid and off-grid relay is connected between the inverter side port and the grid side port, and the manual bypass air switch is connected between the inverter side port and the grid side port. The control circuit is respectively connected to the inverter side port, the grid side port, the inverter and the on-grid and off-grid relay, and the control circuit is used to detect the voltage of the inverter side port, the voltage of the grid side port and the operating state of the inverter; when the on-grid and off-grid relay is disconnected, if it is detected that the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold value, and the inverter is in an operating state, a disturbance instruction is sent to the inverter. The inverter is used to control the effective voltage of its output to be a first voltage and a second voltage in sequence according to the disturbance instruction, and the first voltage is different from the second voltage. The control circuit is also used to detect the voltage difference between the two ends of the manual bypass air switch after sending the disturbance instruction, and send an alarm signal if the voltage difference is less than the second threshold value. The alarm signal is used to indicate that the manual bypass air switch is in a closed state.

[0030] In summary, the present application provides a method for detecting the closure of a backup power system and a manual bypass air switch. The control circuit in the on-grid and off-grid controller can detect the voltage of the inverter side port of the on-grid and off-grid controller, the voltage of the grid side port, and the operating status of the inverter. Under the premise that the on-grid and off-grid relay is disconnected, if the control circuit detects that the voltage difference between the two ends of the manual bypass air switch is less than the second threshold, it can be determined that the voltage of the inverter side port of the on-grid and off-grid controller is close to the voltage of the grid side port. At this time, if the control circuit detects that the inverter is in a non-operating state, that is, the inverter does not output a voltage to the inverter side port, and the voltages of the inverter side port and the grid side port are both greater than the first threshold, the control circuit can determine that the voltage of the inverter side port is provided by the grid through the closed manual bypass air switch. Thus, the control circuit can accurately determine that the manual bypass air switch is in a closed state and send an alarm signal. Since the control circuit can determine whether the manual bypass air switch is closed based on the operating status of the inverter and the voltage difference across the manual bypass air switch, false detection can be effectively avoided, ensuring high accuracy in detecting the closing status of the manual bypass air switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of a backup power system provided in an embodiment of the present application;

[0032] Figure 2 is a structural schematic diagram of another backup power system provided in an embodiment of the present application;

[0033] Figure 3 It is a structural diagram of an on-grid and off-grid controller provided in an embodiment of the present application;

[0034] Figure 4 This is a flow chart of a closure detection method for a manual bypass air switch provided in an embodiment of the present application. DETAILED DESCRIPTION

[0035] The backup power system and the closing detection method of the manual bypass air switch provided by the embodiments of the present application are described in detail below in conjunction with the accompanying drawings. First, the key terms involved in the embodiments of the present application are introduced.

[0036] Inverter (INV): Also known as a power converter, it is used to convert direct current (DC) output by photovoltaic panels (also known as solar panels) or energy storage batteries into alternating current (AC), and transmit the AC power to the power grid, or power loads connected to the power system.

[0037] On-grid and off-grid controller: also called on-grid and off-grid control box or back-up box, it is connected between the inverter and the grid and is used to switch between on-grid and off-grid according to the voltage conditions on both sides of the grid and the inverter.

[0038] On-grid: The inverter converts the DC power generated by the photovoltaic panel into AC power and then connects it to the grid. In the on-grid state, the load is powered by the grid or the inverter.

[0039] Off-grid: A state of independent operation without relying on the power grid. In the off-grid state, the inverter can convert the DC power provided by the photovoltaic panel or energy storage battery into AC power to supply power to the load.

[0040] Backup load: It is an important load that needs to be powered by an inverter in conjunction with photovoltaic panels or energy storage batteries when there is a power outage on the grid side. For example, backup loads can include lighting equipment in household loads.

[0041] Non-backup loads: non-critical loads that do not need to be powered when the grid fails, to ensure that backup loads can be powered for a long time. For example, non-backup loads may include smart home appliances in household loads.

[0042] Figure 1 Schematic diagram of a backup power system (also called a whole-house backup power system) provided in an embodiment of the present application. Figure 1 As shown, the backup power system includes: an inverter and an on-grid and off-grid controller. The DC end of the inverter is connected to a DC power supply, which may include a photovoltaic panel. Alternatively, refer to Figure 1 The DC power supply includes a photovoltaic panel and an energy storage battery. The AC end of the inverter is connected to the inverter side INV port of the on-grid controller, and the grid side GRID port of the on-grid controller is used to connect to the grid. Figure 2 As shown, the inverter-side INV port of the on-grid and off-grid controller is also used to connect to the backup power load, and the grid-side GRID port of the on-grid and off-grid controller is also used to connect to the non-backup power load.

[0043] The on-grid and off-grid controller usually includes an on-grid and off-grid relay and a manual bypass air switch K0, which is also called a bypass air switch, a bypass air circuit breaker or a bypass relay. The manual bypass air switch K0 can be manually controlled to close or open by the user. In addition, the manual bypass air switch K0 also has an overcurrent protection function, that is, the manual bypass air switch K0 can automatically disconnect when the current flowing through it is greater than a certain threshold.

[0044] In order to meet safety requirements, such as Figure 1 and Figure 2As shown, the grid-connected and off-grid relay generally includes an inverter-side relay (K1 and K3) and a grid-side relay (K2 and K4). The manual bypass air switch K0 is connected in parallel at both ends of the inverter-side relay (K1 and K3) and the grid-side relay (K2 and K4). Each of the above relays is in a disconnected state by default, which is used to disconnect the inverter and the grid. Correspondingly, at this time, the backup power system is off-grid, and the inverter converts the DC power provided by the DC power supply into AC power to supply power to the backup power load. When the inverter-side relay (K1 and K3) and the grid-side relay (K2 and K4) are both closed, the backup power system is grid-connected. At this time, the inverter can transmit the AC power to the grid through the grid-connected and off-grid controller. And, at this time, the backup power load and the non-backup power load can be powered by the inverter, or can be powered by the grid.

[0045] When the internal hardware circuit of the grid-connected and off-grid controller fails, the user can manually close the manual bypass air switch K0 to directly short-circuit the inverter side relay (K1 and K3) and the grid side relay (K2 and K4) to transmit the grid power to the backup load, thereby supplying power to the backup load.

[0046] However, when the on-grid controller is not faulty and the backup power system is running off-grid, that is, when the inverter-side relays (K1 and K3) and the grid-side relays (K2 and K4) are both disconnected, if the manual bypass air switch K0 is closed due to misoperation or device failure, it will affect the safety and stability of the backup power system. For example, when the user shuts down the grid side for maintenance and other operations, if the manual bypass air switch K0 is closed, the output voltage of the inverter in the off-grid state will be directly output to the grid-side GRID port through the closed manual bypass air switch K0, posing a risk of electric shock.

[0047] Alternatively, when the grid-side GRID port is out of power, if the manual bypass air switch K0 is closed, the grid-connected and off-grid controller will detect that there is voltage at the grid-side GRID port and consider the grid to be normal. At this time, the grid-connected and off-grid controller will perform the off-grid switching operation, that is, the grid-connected and off-grid controller will close the inverter-side relays (K1 and K3) and the grid-side relays (K2 and K4). However, since the grid actually has no voltage and cannot maintain grid connection, the grid-connected and off-grid controller will repeatedly switch between grid connection and off-grid connection, affecting system stability.

[0048] Based on the above analysis, in order to ensure the safety and stability of the backup power system, when the inverter side relays (K1 and K3) and the grid side relays (K2 and K4) are both in the disconnected state, the grid-connected and off-grid controller needs to accurately detect whether the manual bypass air switch K0 is closed. When the manual bypass air switch K0 is detected to be closed, the grid-connected and off-grid controller can send an alarm signal to instruct the user to disconnect the manual bypass air switch K0. Usually, the grid-connected and off-grid controller can directly detect the voltage difference across the manual bypass air switch K0, and judge whether the manual bypass air switch K0 is closed based on the size of the voltage difference. For example, if the voltage difference is less than the threshold, the manual bypass air switch K0 is judged to be closed. However, there is a probability of false detection in this detection method, and the detection accuracy is low.

[0049] For example, when the inverter-side relays (K1 and K3) and the grid-side relays (K2 and K4) are both in the disconnected state, and the manual bypass air switch K0 is also disconnected, if there is power at both the AC end and the grid side of the inverter, and when detecting the voltage difference across the manual bypass air switch K0, the voltages at the AC end of the inverter and the grid side have the same amplitude and phase, the detected voltage difference will be smaller, and the manual bypass air switch K0 will be mistakenly judged to be closed.

[0050] The embodiment of the present application provides a grid-connected and off-grid controller, which can be applied to Figure 1 or Figure 2 In the application scenario shown, it is possible to accurately detect whether the manual bypass air switch K0 is closed. Figure 3 As shown, the on-grid and off-grid controller has an inverter side INV port and a grid side GRID port, wherein the inverter side INV port is used to connect to the inverter, and the grid side GRID port is used to connect to the grid. In addition, the on-grid and off-grid controller includes: an on-grid and off-grid relay 10, a manual bypass air switch K0 and a control circuit 20.

[0051] Among them, the grid-connected and off-grid relay 10 is connected between the inverter side INV port and the grid side GRID port, and the manual bypass air switch K0 is also connected between the inverter side INV port and the grid side GRID port. The on-off state of the grid-connected and off-grid relay 10 is controlled by the control circuit 20. The on-off state of the manual bypass air switch K0 can be manually controlled, and the manual bypass air switch K0 can also be automatically disconnected if the current flowing through it is detected to be greater than a certain threshold in the closed state. In addition, when the manual bypass air switch K0 is closed, the grid-connected and off-grid relay 10 can be short-circuited.

[0052] The control circuit 20 is connected to the inverter side INV port, the grid side GRID port, the inverter and the grid-connected and off-grid relay respectively. The control circuit 20 is used to detect the voltage of the inverter side INV port, the voltage of the grid side GRID port and the operating state of the inverter; if the voltage of the inverter side INV port and the voltage of the grid side GRID port are both greater than the first threshold when the grid-connected and off-grid relay 10 is disconnected, the voltage difference across the manual bypass air switch K0 is less than the second threshold, and the inverter is in a non-operating state, an alarm signal is issued. The alarm signal is used to indicate that the manual bypass air switch K0 is in a closed state.

[0053] The voltage difference across the manual bypass air switch K0 is equal to the voltage difference between the INV port on the inverter side and the GRID port on the grid side. That is, the control circuit 20 can calculate the voltage difference across the manual bypass air switch K0 by taking the voltage difference between the INV port on the inverter side and the GRID port on the grid side.

[0054] It is understandable that the first threshold is greater than the second threshold. The first threshold may be pre-configured in the control circuit 20, and the first threshold may be based on the rated voltage U n For example, the first threshold value may be k1U n , where k1 is the first coefficient, and the first coefficient k1 can be greater than 0 and less than 1. For example, the first coefficient k1 can be 0.5. It can also be understood that the second threshold value can be a smaller voltage value pre-configured in the control circuit 20. If the voltage difference across the manual bypass air switch K0 is less than the second threshold value, it indicates that the voltage of the inverter side INV port and the voltage of the grid side GRID port are relatively close. The second threshold value can also be based on the rated voltage U n For example, the second threshold value may be k2U n , wherein k2 is a second coefficient, and the value of the second coefficient k2 may be greater than 0 and less than the first coefficient k1. For example, the value range of the coefficient k2 may be 0.01 to 0.1, such as 0.02.

[0055] It can also be understood that the inverter can send a state indication signal to the control circuit 20 in the grid-connected and off-grid controller, and the state indication signal is used to indicate that the inverter is in an operating state or a non-operating state. Among them, the non-operating state may refer to a state in which the inverter does not perform power conversion, that is, a state in which the inverter does not output power. The operating state may refer to a state in which the inverter performs power conversion and outputs power. For example, the operating state of the inverter may include an off-grid operating state and a grid-connected operating state. The non-operating state of the inverter may include a startup state and a shutdown state.

[0056] Optionally, the state indication signal sent by the inverter may include a flag bit, and when the flag bit takes different values, it can indicate that the inverter is in different states. For example, when the flag bit takes a value of 1, it can indicate that the inverter is in an operating state; when the flag bit takes a value of 0, it can indicate that the inverter is in a non-operating state.

[0057] As described above, when the inverter is in a non-operating state, the inverter will not output power to the inverter side INV port of the grid-connected and off-grid controller, that is, it will not output voltage. Based on this, if the voltage difference between the two ends of the manual bypass air switch K0 is small under the premise that the grid-connected and off-grid relay 10 is disconnected, that is, the voltage of the inverter side INV port and the voltage of the grid side GRID port are relatively close, and the voltage of the inverter side INV port and the voltage of the grid side GRID port are both greater than the first threshold value, then the control circuit 20 can determine that the voltage of the inverter side INV port is provided by the grid through the closed manual bypass air switch K0. Thus, the control circuit 20 can accurately determine that the manual bypass air switch K0 is in a closed state and sends an alarm signal. Moreover, based on the above analysis, it can be seen that the solution provided by the embodiment of the present application can accurately detect whether the manual bypass air switch K0 is closed in the scenario where the grid has electricity and the inverter is in a non-operating state.

[0058] Optionally, the warning signal may include a sound warning signal and / or a light warning signal. The user may disconnect the manual bypass air switch K0 in time according to the warning signal.

[0059] Optionally, after the control circuit 20 determines that the manual bypass air switch K0 is in a closed state, it can also control the grid-connected and off-grid relay 10 to remain in an open state. In addition, the control circuit 20 can send a shutdown command to the inverter, and the shutdown command can be used to instruct the inverter to shut down. Among them, the inverter shutdown can refer to the inverter stopping power conversion. The control circuit 20 controls the grid-connected and off-grid relay 10 to remain in an open state, which can also be considered as controlling the grid-connected and off-grid controller to shut down. In this way, not only can the safety risks be effectively reduced, but also the grid-connected and off-grid controller can be prevented from repeatedly switching between grid-connected and off-grid, affecting the stability of the system.

[0060] Optionally, refer to Figure 1 The inverter and the grid-connected and off-grid controller can establish a communication connection through the RS-485 bus. Accordingly, the inverter can send a status indication signal to the control circuit 20 in the grid-connected and off-grid controller through the RS-485 bus. In addition, the control circuit 20 can send a shutdown command to the inverter through the RS-485 bus.

[0061] Alternatively, refer to Figure 2The backup power system also includes a photovoltaic system controller, and a communication connection can be established between the inverter and the grid-connected and off-grid controller through the RS-485 bus and the photovoltaic system controller. Correspondingly, the inverter can send a status indication signal to the control circuit 20 in the grid-connected and off-grid controller through the RS-485 bus and the photovoltaic system controller. In addition, the control circuit 20 can send a shutdown command to the inverter through the RS-485 bus and the photovoltaic system controller. For example, the inverter can send a status indication signal to the photovoltaic system controller through the RS-485 bus, and the photovoltaic system controller can then forward the status indication signal to the control circuit 20 in the grid-connected and off-grid controller through the RS-485 bus. The control circuit 20 can send a shutdown command to the photovoltaic system controller through the RS-485 bus, and the photovoltaic system controller can then forward the shutdown command to the inverter through the RS-485 bus.

[0062] Optionally, the control circuit 20 can be used to: if the voltage of the inverter side INV port and the voltage of the grid side GRID port are both greater than the first threshold, the voltage difference across the manual bypass air switch K0 is less than the second threshold for a first time period, and the inverter is in a non-operating state, then send out an alarm signal. The first time period t1 is also pre-stored in the control circuit 20, for example, the value range of the first time period t1 can be 2 seconds to 5 seconds, such as 3 seconds.

[0063] It can be understood that if the duration of the state that the voltage difference across the manual bypass air switch K0 is less than the second threshold value reaches the first duration, that is, the voltage difference across the manual bypass air switch K0 is continuously and stably less than the second threshold value, the control circuit 20 can more accurately determine that the manual bypass air switch K0 is in the closed state. Thus, the accuracy of the closing detection can be effectively ensured.

[0064] Optionally, in an embodiment of the present application, the control circuit 20 can perform system initialization after powering on, and the grid-connected relay 10 will be disconnected during system initialization. Afterwards, the control circuit 20 can first detect the voltage of the INV port on the inverter side and the voltage of the GRID port on the grid side. If the voltage of the INV port on the inverter side, or the voltage of the GRID port on the grid side is not greater than the first threshold, that is, the voltage of the port on either side of the grid-connected controller is lower, the control circuit 20 can determine that the manual bypass air switch K0 is in an open state. Furthermore, the control circuit 20 does not need to perform subsequent closure detection procedures, and the backup power system can continue to operate normally. If the voltages of both ports are greater than the first threshold, the control circuit 20 can continue to detect the voltage difference across the manual bypass air switch K0. If the voltage difference across the manual bypass air switch K0 is greater than or equal to the second threshold, the control circuit 20 can determine that the manual bypass air switch K0 is not closed, and terminate the subsequent closure detection process, and the backup power system can continue to operate normally. If the voltage difference across the manual bypass air switch K0 is less than the second threshold, the control circuit 20 can continue to detect whether the inverter is in operation. If the inverter is not in operation, the control circuit 20 can determine that the manual bypass air switch K0 is in a closed state and send an alarm signal.

[0065] It is understandable that the control circuit 20 may also detect the operating state of the inverter first, and then detect the voltage of the inverter-side INV port and the voltage of the grid-side GRID port. The embodiment of the present application does not limit the detection order of the above-mentioned states.

[0066] It can also be understood that if the control circuit 20 detects that the voltage of the inverter side INV port and the voltage of the grid side GRID port are not greater than the first threshold, that is, it detects that both the inverter side INV port and the grid side GRID port are out of power, then even if the manual bypass air switch K0 is closed at this time, it will not affect the safety and system stability. Therefore, the control circuit 20 may no longer perform the subsequent closing detection process.

[0067] In summary, the embodiment of the present application provides a grid-connected off-grid controller, in which the control circuit can detect the voltage difference between the two ends of the manual bypass air switch and the operating state of the inverter. Under the premise that the grid-connected off-grid relay is disconnected, if the control circuit detects that the voltage difference between the two ends of the manual bypass air switch is less than the second threshold, it can be determined that the voltage of the inverter side port of the grid-connected off-grid controller is close to the voltage of the grid side port. At this time, if the control circuit detects that the inverter is in a non-operating state, that is, the inverter does not output voltage to the inverter side port, and the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold, the control circuit can determine that the voltage of the inverter side port is provided by the grid through the closed manual bypass air switch. Thus, the control circuit can accurately determine that the manual bypass air switch is in a closed state and send an alarm signal. Since the control circuit can judge whether the manual bypass air switch is closed in combination with the operating state of the inverter and the voltage difference between the two ends of the manual bypass air switch, it can effectively avoid false detection and ensure that the detection accuracy of the closed state of the manual bypass air switch is high.

[0068] Moreover, the above detection process does not require controlling the on / off state of the detected relay (i.e., the manual bypass air switch), that is, no manual intervention is required. For the manual bypass air switch that cannot be closed or opened by driving automatic control, accurate detection of its closing state can be achieved.

[0069] The embodiment of the present application provides another on-grid and off-grid controller, which can be applied to Figure 1 or Figure 2 In the application scenario shown, it is possible to accurately detect whether the manual bypass air switch K0 is closed. Figure 3 As shown, the on-grid and off-grid controller has an inverter side INV port and a grid side GRID port, wherein the inverter side INV port is used to connect to the inverter, and the grid side GRID port is used to connect to the grid. In addition, the on-grid and off-grid controller includes: an on-grid and off-grid relay 10, a manual bypass air switch K0 and a control circuit 20.

[0070] Among them, the control circuit 20 is respectively connected to the inverter side INV port, the grid side GRID port, the inverter and the grid-connected and off-grid relay. The control circuit 20 is used to detect the voltage of the inverter side INV port, the voltage of the grid side GRID port and the operating state of the inverter; when the grid-connected and off-grid relay 10 is disconnected, if it is detected that the voltage of the inverter side INV port and the voltage of the grid side GRID port are both greater than the first threshold value, and the inverter is in operation, a disturbance instruction is sent to the inverter. The disturbance instruction is used to instruct the inverter to control the effective voltage of its output to be the first voltage and the second voltage in sequence, and the first voltage and the second voltage are different. That is, the inverter can output an effective voltage with an amplitude disturbed within a certain range to the inverter side INV port of the grid-connected and off-grid controller according to the disturbance instruction, that is, output a disturbance voltage to the inverter side INV port of the grid-connected and off-grid controller.

[0071] The control circuit 20 is also used to detect the voltage difference between the two ends of the manual bypass air switch K0 after sending the disturbance command, and send an alarm signal if the voltage difference is detected to be less than the second threshold. The alarm signal is used to indicate that the manual bypass air switch K0 is in a closed state. The voltage difference between the two ends of the manual bypass air switch K0 is equal to the difference between the voltage of the inverter side INV port and the voltage of the grid side GRID port.

[0072] For explanations on the first threshold, the second threshold and the operating state of the inverter, reference may be made to the relevant description in the aforementioned embodiments. For implementation of the alarm signal, reference may be made to the relevant description in the aforementioned embodiments, which will not be repeated here.

[0073] It is understandable that the voltage difference across the manual bypass air switch K0 is less than the second threshold value, indicating that the voltage of the inverter side INV port of the grid-side controller is close to the voltage of the grid-side GRID port. In an embodiment of the present application, under the premise that the grid-connected and off-grid relay 10 is disconnected, after the inverter outputs the disturbed effective voltage to the inverter side INV port, the voltage of the inverter side INV port (i.e., the effective voltage of the inverter side INV port) will fluctuate within a certain range. At this time, if the control circuit 20 detects that the voltage difference across the manual bypass air switch K0 is less than the second threshold value, it indicates that the grid is out of power, and the voltage of the grid side GRID port can pass through the closed manual bypass air switch K0, and fluctuate with the voltage fluctuation of the inverter side INV port. Thus, the control circuit 20 can accurately determine that the manual bypass air switch K0 is in a closed state and send an alarm signal. The above-mentioned closed detection method can effectively avoid false detection and ensure that the detection accuracy of the closed state of the manual bypass air switch is high.

[0074] Based on the above analysis, it can be seen that the solution provided in the embodiment of the present application can accurately detect whether the manual bypass air switch K0 is closed when the inverter is in operation and the grid is out of power.

[0075] It can also be understood that if the inverter is in operation and the grid has electricity, when the manual bypass air switch K0 and the grid-connected and off-grid relay 10 are both disconnected, the inverter can operate normally off-grid. If the inverter is in operation and the grid has electricity, when the manual bypass air switch K0 is closed, the inverter can detect an alarm and shut down, that is, the inverter will be in a non-operating state. At this time, the grid-connected and off-grid controller can detect that the manual bypass air switch K0 is in a closed state through the solution provided in the aforementioned embodiment.

[0076] Optionally, after the control circuit 20 determines that the manual bypass air switch K0 is in a closed state, it can also control the on-grid relay 10 to remain in an open state. In addition, the control circuit 20 can send a shutdown command to the inverter, and the shutdown command can be used to instruct the inverter to shut down. Among them, the inverter shutdown can mean that the inverter stops performing power conversion. The control circuit 20 controls the on-grid relay 10 to remain in an open state, which can also be considered as controlling the on-grid controller to shut down.

[0077] Optionally, the control circuit 20 is used to send a disturbance command to the inverter when the grid-connected or off-grid relay 10 is disconnected, if it is detected that the voltage of the INV port on the inverter side and the voltage of the GRID port on the grid side are both greater than a first threshold, the voltage difference across the manual bypass air switch K0 is less than a second threshold, and it is detected that the inverter is in operation.

[0078] It can be understood that when the on-grid relay 10 is disconnected, if the control circuit 20 detects that the voltage of the inverter-side INV port and the voltage of the grid-side GRID port are both greater than the first threshold, and the voltage difference across the manual bypass air switch K0 is less than the second threshold, it can be determined that the manual bypass air switch K0 may be in a closed state. Therefore, the control circuit 20 can continue to execute the subsequent closing detection process, that is, according to the inverter being in the running state, send a disturbance instruction to the inverter.

[0079] It can also be understood that if the voltage of the inverter side INV port of the grid-connected and off-grid controller, or the voltage of the grid-side GRID port is not greater than the first threshold, that is, the voltage of the port on either side of the grid-connected and off-grid controller is lower, then the control circuit 20 can determine that the manual bypass air switch K0 is in an open state. Furthermore, the control circuit 20 does not need to perform the subsequent closure detection process, and the backup power system can continue to operate normally. If the voltage of the inverter side INV port of the grid-connected and off-grid controller and the voltage of the grid-side GRID port are both greater than the first threshold, the control circuit 20 can determine that the manual bypass air switch K0 may be in a closed state, and can continue to execute the subsequent closure detection process, such as continuing to detect whether the voltage difference across the manual bypass air switch K0 is less than the second threshold. In this way, the accuracy of the subsequent closure detection can be ensured.

[0080] Furthermore, if the control circuit 20 detects that the voltage difference across the manual bypass air switch K0 is not less than the second threshold, that is, the voltage of the inverter-side INV port of the grid-connected and off-grid controller differs greatly from the voltage of the grid-side GRID port, the control circuit 20 can determine that the manual bypass air switch K0 is not closed. Accordingly, the control circuit 20 can terminate the closing detection process, and the backup power system can continue to operate normally.

[0081] Optionally, the control circuit 20 is used to send a disturbance command to the inverter when the grid-connected or off-grid relay 10 is disconnected, if it is detected that the voltage of the INV port on the inverter side and the voltage of the GRID port on the grid side are both greater than a first threshold, the voltage difference across the manual bypass air switch K0 is less than the second threshold for a first time period, and it is detected that the inverter is in operation.

[0082] The first time duration t1 may be pre-stored in the control circuit 20, for example, the value range of the first time duration t1 may be 2 seconds to 5 seconds, for example, 3 seconds. It is understandable that if the duration of the state in which the voltage difference across the manual bypass air switch K0 is less than the second threshold reaches the first time duration, the control circuit 20 may determine that the probability that the manual bypass air switch K0 is in the closed state is high, and therefore a disturbance instruction may be sent to the inverter to further verify whether the manual bypass air switch K0 is in the closed state.

[0083] Optionally, the control circuit 20 is used to send an alarm signal if it is detected that the voltage difference across the manual bypass air switch K0 is less than the second threshold value for a third time period within the second time period after the disturbance instruction is sent. That is, the control circuit 20 can continuously detect the voltage difference across the manual bypass air switch K0 within the detection time window after the disturbance instruction is sent, and the duration of the detection time window is the second time period. If the voltage difference across the manual bypass air switch K0 is less than the second threshold value for a third time period within the detection time window, the control circuit 20 can accurately determine that the manual bypass air switch K0 is in a closed state and send an alarm signal.

[0084] The second time length t2 and the third time length t3 may both be fixed values ​​pre-configured in the control circuit 20, and the second time length t2 is greater than the third time length t3. For example, the second time length t2 may be 10 seconds, and the third time length t3 may be 6 seconds.

[0085] Optionally, the disturbance instruction issued by the control circuit 20 may be used to instruct the inverter to output the first voltage for a fourth duration and the second voltage for a fifth duration, wherein the third duration is greater than the fourth duration and greater than the fifth duration.

[0086] It can be understood that the first voltage and the second voltage can be based on the rated voltage U n For example, the first voltage may be (1+k3)U n , the second voltage can be (1-k3)U n Alternatively, the first voltage may be (1-k3)U n , the second voltage can be (1+k3)U n Wherein, k3 is the third coefficient, and the third coefficient k3 may be a number greater than 0 and less than or equal to 0.2, for example, the third coefficient k3 may be 0.05 or 0.1. That is, the inverter may control the output voltage of its AC end to be disturbed within a small range according to the disturbance instruction.

[0087] It can also be understood that the fourth duration t4 and the fifth duration t5 can be equal or unequal, and the embodiment of the present application does not limit this. In addition, the third duration t3 needs to be greater than the fourth duration t4 and greater than the fifth duration t5 to ensure the accuracy of the detection. Optionally, the third duration t3 can be greater than or equal to the sum of the fourth duration t4 and the fifth duration t5. For example, the fourth duration t4 and the fifth duration t5 can both be 3 seconds. The value range of the third duration t3 can be 5 seconds to 10 seconds, for example, 6 seconds.

[0088] Since the inverter can control the effective voltage of its output to be continuously the first voltage within the fourth time length t4 and the effective voltage of its output to be continuously the second voltage within the fifth time length t5 after receiving the disturbance instruction, it can be known that the effective voltage of the output voltage of the inverter will fluctuate at least within a time range greater than the fourth time length t4 or greater than the fifth time length t5. Correspondingly, if the control circuit 20 detects that the voltage difference across the manual bypass air switch K0 is less than the second threshold within the third time length t3 (i.e., greater than the fourth time length t4 and greater than the fifth time length t5), it can accurately determine that the manual bypass air switch K0 is in a closed state.

[0089] It can also be understood that the voltage values ​​of the first voltage and the second voltage, and the duration values ​​of the fourth duration and the fifth duration can be pre-configured in the inverter. Alternatively, the voltage values ​​of the first voltage and the second voltage, and / or the duration values ​​of the fourth duration and the fifth duration can be indicated by the disturbance instruction. For example, the disturbance instruction can carry a third coefficient k3, and the inverter can determine the voltage values ​​of the first voltage and the second voltage according to the third coefficient k3, and output the effective voltage of the disturbance.

[0090] It can also be understood that the voltage of each port detected by the grid-connected and off-grid controller in the embodiment of the present application, and the voltage difference across the manual bypass air switch K0 can all refer to the effective voltage, that is, the effective value of the AC voltage.

[0091] In summary, an embodiment of the present application provides a grid-connected and off-grid controller, in which the control circuit can indicate the effective voltage of the inverter output disturbance under the premise that the grid-connected and off-grid relay is disconnected. After the inverter outputs the effective voltage of the disturbance to the inverter side port of the grid-connected and off-grid controller, the voltage of the inverter side port will fluctuate within a certain range. At this time, if the control circuit detects that the voltage difference between the two ends of the manual bypass air switch is less than the second threshold, it can be determined that the voltage of the grid side port can pass through the closed manual bypass air switch and fluctuate with the voltage fluctuation of the inverter side port. Thus, the control circuit can accurately determine that the manual bypass air switch is in a closed state and send an alarm signal. The above-mentioned closure detection method can effectively avoid false detection and ensure that the detection accuracy of the closed state of the manual bypass air switch is high.

[0092] Moreover, the above detection process does not require controlling the on / off state of the detected relay (i.e., the manual bypass air switch), that is, no manual intervention is required. For the manual bypass air switch that cannot be closed or opened by driving automatic control, accurate detection of its closing state can be achieved.

[0093] Figure 41 is a flow chart of a manual bypass air switch closure detection provided in an embodiment of the present application. The closure detection process can be applied to the control circuit in the grid-connected and off-grid controller provided in the above embodiment. Figure 4 As shown, the closing detection process of the manual bypass air switch K0 may include:

[0094] Step S1: The on-grid and off-grid controller is powered by an inverter or a power grid.

[0095] Step S2: The on-grid and off-grid controller system initializes and disconnects all relays, and starts the closing detection process of the manual bypass air switch K0.

[0096] It is understandable that the on-grid and off-grid controller can disconnect the on-grid and off-grid relays, such as disconnecting the inverter-side relay and the grid-side relay, when the system is initialized. After that, the closing detection process of the manual bypass air switch K0 can be started.

[0097] Step S3: The on-grid and off-grid controller detects whether the INV port voltage on the inverter side and the GRID port voltage on the grid side are both greater than a first threshold.

[0098] The first threshold value can be k1U n , U n is the rated voltage of the power grid. The first coefficient k1 may be greater than 0 and less than 1. For example, the first coefficient k1 may be 0.5. If both the INV port voltage on the inverter side and the GRID port voltage on the grid side are greater than the first threshold, the grid-connected and off-grid controller may determine that the manual bypass air switch K0 may be closed, and continue to execute the following step S4. If either the INV port voltage on the inverter side or the GRID port voltage on the grid side is not greater than the first threshold, the grid-connected and off-grid controller may determine that the bypass switch K0 is not closed, and terminate the closing detection process, and the backup power system operates normally.

[0099] Step S4: The on-grid and off-grid controller calculates the voltage difference ΔV across the manual bypass air switch K0 according to the INV port voltage on the inverter side and the GRID port voltage on the grid side.

[0100] It can be understood that since the two ends of the manual bypass air switch K0 are respectively connected to the inverter side INV port and the grid side GRID port, the voltage difference between the inverter side INV port voltage and the grid side GRID port voltage is the voltage difference ΔV across the manual bypass air switch K0.

[0101] Step S5: The grid-connected and off-grid controller detects whether the voltage difference ΔV across the manual bypass air switch K0 is less than a second threshold value and lasts for a first time period.

[0102] The second threshold value may be k2U nThe value range of the second coefficient k2 may be 0.01 to 0.1, such as 0.02 or 0.04. The value range of the first duration t1 may be 2 seconds to 5 seconds, such as 3 seconds.

[0103] If the voltage difference ΔV across the manual bypass air switch K0 is less than the second threshold value and lasts for the first time period, the grid-connected and off-grid controller can determine that the manual bypass air switch K0 may be closed, and continue to perform the following step S6. If the voltage difference ΔV across the manual bypass air switch K0 does not meet the above conditions, for example, the voltage difference ΔV is not less than the second threshold value, or the time period for which the voltage difference ΔV is less than the second threshold value does not reach the first time period, the grid-connected and off-grid controller can determine that the bypass switch K0 is not closed, and can terminate the closing detection process, and the backup power system operates normally.

[0104] Step S6: The on-grid and off-grid controller detects whether the inverter is in operation.

[0105] Among them, the inverter operating state can be transmitted by the inverter to the grid-connected and off-grid controller through the RS-485 bus and the photovoltaic system controller. Optionally, the operating state of the inverter may include an off-grid operating state and a grid-connected operating state. It can be understood that in the above step S2, since the grid-connected and off-grid controller has disconnected the grid-connected and off-grid relay, the inverter is usually not in a grid-connected operating state. That is, the above operating state usually refers to an off-grid operating state. It can also be understood that the non-operating state of the inverter may refer to a state in which the inverter stops performing power conversion, that is, the inverter does not output voltage in the non-operating state.

[0106] In step S6, if the grid-connected and off-grid controller detects that the inverter is in operation, the following step S7 may be continued. If the grid-connected and off-grid controller detects that the inverter is in non-operational state, it may be determined that the bypass switch K0 is in a closed state. That is, if the grid-connected and off-grid controller detects that the voltage difference ΔV across the manual bypass air switch K0 is less than the second threshold value and lasts for the first time period, and the inverter is in non-operational state, it may be determined that the bypass switch K0 is in a closed state. Afterwards, the grid-connected and off-grid controller may execute the following step S10.

[0107] Step S7: The on-grid and off-grid controller sends a disturbance instruction to the inverter.

[0108] For example, the on-grid and off-grid controller can send disturbance instructions (also called voltage disturbance instructions or control instructions) to the inverter through the RS-485 bus and the photovoltaic system controller.

[0109] Step S8: The inverter outputs a disturbance voltage.

[0110] After receiving the disturbance instruction, the inverter outputs the disturbance voltage, that is, the effective voltage of the output voltage of the inverter can be disturbed within a small amplitude range. For example, the inverter can first output the first voltage and last for the fourth time, and then output the second voltage and last for the fifth time. The amplitude of the first voltage can be (1+k3)U n , the amplitude of the second voltage can be (1-k3)U n , the third coefficient k3 may be 0.05. The fourth duration and the fifth duration may be equal, for example, 3 seconds.

[0111] Step S9: within the second time period after the grid-connected and off-grid controller issues the voltage disturbance instruction, it detects whether the voltage difference ΔV across the manual bypass air switch K0 is less than the second threshold value and lasts for a third time period.

[0112] Assuming that the time when the voltage disturbance instruction is issued is T0, the grid-connected and off-grid controller can continuously detect the voltage difference ΔV across the manual bypass air switch K0 within the detection time window from time T0 to time T1. The time length between time T0 and time T1 is the second time length t2. Within the detection time window, if the voltage difference ΔV across the manual bypass air switch K0 is less than the second threshold value and lasts for the third time length t3, the grid-connected and off-grid controller can determine that the bypass switch K0 is in a closed state, and can execute the following step S10.

[0113] Within the detection time window, if the voltage difference ΔV across the manual bypass air switch K0 does not meet the above conditions, for example, if the voltage difference ΔV is not less than the second threshold, or the duration of being less than the second threshold does not reach the third duration t3, the grid-connected and off-grid controller can determine that the bypass switch K0 is not closed, and can terminate the closing detection process, and the backup power system operates normally.

[0114] It is understandable that the third time length t3 is less than the second time length t2, and greater than the fourth time length t4 and the fifth time length t5. For example, the second time length t2 may be 10 seconds, and the third time length t3 may be in the range of 5 to 10 seconds, for example, 6 seconds.

[0115] Step S10: the on-grid and off-grid controller warns that the manual bypass air switch K0 is closed.

[0116] After the on-grid controller determines that the manual bypass air switch K0 is in a closed state based on the judgment in the above step S6 or the above step S9, it can issue an alarm signal, which is used to indicate that the manual bypass air switch K0 is closed.

[0117] Step S11: The inverter and the on-grid and off-grid controller are shut down.

[0118] After the above step S10, the grid-connected and off-grid controller may also report a shutdown instruction to the photovoltaic system controller, so that the photovoltaic system controller sends the shutdown instruction to the inverter. The inverter may then shut down based on the shutdown instruction, that is, the inverter may stop outputting power. At the same time, the grid-connected and off-grid controller may also shut down after issuing an alarm signal and a shutdown instruction, that is, the grid-connected and off-grid relay in the grid-connected and off-grid controller may remain in a disconnected state.

[0119] It is understandable that the order of the above steps can be adjusted appropriately, and the steps can be increased or decreased accordingly according to the situation. For example, the execution order of the above steps S3, S5 and S6 can be adjusted according to the situation. For example, step S5 can be executed before step S3, or step S6 can be executed before step S5.

[0120] The embodiment of the present application also provides a method for detecting the closing of a manual bypass air switch, which can be applied to the backup power system provided in the above embodiment. The method includes:

[0121] Step 101: Detect the voltage of the inverter side port, the voltage of the grid side port and the operating status of the inverter.

[0122] Step 102: If, when the on-grid and off-grid relay is disconnected, the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold, the voltage difference across the manual bypass air switch is less than the second threshold, and the inverter is in a non-operating state, an alarm signal is issued.

[0123] The alarm signal is used to indicate that the manual bypass air switch is in a closed state. The voltage difference across the manual bypass air switch is equal to the difference between the voltage of the inverter side port and the voltage of the grid side port. In addition, the first threshold is greater than the second threshold.

[0124] Optionally, the above step 102 may include: if the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold, the voltage difference across the manual bypass air switch is less than the second threshold for a first time period, and the inverter is in a non-operating state, an alarm signal is issued.

[0125] Optionally, after the above step 102, the method may further include:

[0126] Step 103, control the on-grid and off-grid relay to remain in an off state. That is, after detecting that the manual bypass air switch is in a closed state, control the on-grid and off-grid controller to shut down.

[0127] Step 104: Send a shutdown command to the inverter.

[0128] Step 105: The inverter shuts down according to the shutdown instruction.

[0129] Optionally, the above steps 101 to 104 may be executed by a control circuit in the on-grid and off-grid controller. In addition, the control circuit may also receive a status indication signal sent by the inverter and detect the operating status of the inverter based on the status indication signal.

[0130] The present application also provides another method for detecting the closing of a manual bypass air switch, which can be applied to the backup power system provided in the above embodiment. The method includes:

[0131] Step 201: Detect the voltage of the inverter side port, the voltage of the grid side port and the operating status of the inverter.

[0132] Step 202: When the on-grid and off-grid relay is disconnected, if it is detected that the voltage of the inverter side port and the voltage of the grid side port are both greater than a first threshold value, and the inverter is in operation, a disturbance instruction is sent to the inverter.

[0133] Step 203: The inverter controls the effective voltage outputted by the inverter to be the first voltage and the second voltage in sequence according to the disturbance instruction.

[0134] The first voltage is different from the second voltage. That is, the inverter can control the effective voltage outputted by the inverter to be disturbed within a certain range according to the disturbance instruction.

[0135] Step 204: After sending the disturbance instruction, detect the voltage difference across the manual bypass air switch.

[0136] Step 205: If the voltage difference between the two ends of the manual bypass air switch is less than the second threshold, an alarm signal is issued. The alarm signal is used to indicate that the manual bypass air switch is in a closed state.

[0137] Optionally, the above step 202 may include: when the on-grid and off-grid relay is disconnected, if it is detected that the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold, the voltage difference across the manual bypass air switch is less than the second threshold, and the inverter is in operation, a disturbance command is sent to the inverter.

[0138] Optionally, the above step 202 may include: when the on-grid and off-grid relay is disconnected, if it is detected that the voltage of the inverter side port and the voltage of the grid side port are both greater than a first threshold, the voltage difference across the manual bypass air switch is less than the second threshold for a first time period, and the inverter is in operation, a disturbance command is sent to the inverter.

[0139] Optionally, the above step 205 may include: within the second time period after the disturbance instruction is sent, if it is detected that the voltage difference across the manual bypass air switch is less than the second threshold for a third time period, then sending an alarm signal, wherein the second time period is greater than the third time period.

[0140] Optionally, the disturbance instruction is used to instruct the inverter to output the first voltage for a fourth duration and the second voltage for a fifth duration, wherein the first voltage is different from the second voltage, and the third duration is greater than the fourth duration and greater than the fifth duration.

[0141] Optionally, after the above step 205, the method may further include:

[0142] Step 206: Control the on-grid and off-grid relay to remain in an off state. That is, after detecting that the manual bypass air switch is in a closed state, the control circuit can control the on-grid and off-grid controller to shut down.

[0143] Step 207: Send a shutdown command to the inverter.

[0144] Step 208: The inverter shuts down according to the shutdown instruction.

[0145] Optionally, the above steps 201 and 202, and steps 204 to 207 can be performed by a control circuit in the on-grid and off-grid controller. In addition, the control circuit can also receive a status indication signal sent by the inverter, and detect the operating status of the inverter based on the status indication signal.

[0146] It can be understood that the closing detection method of the above-mentioned manual bypass air switch has basically the same implementation method and technical effect as the grid-connected and off-grid controller provided in the aforementioned embodiment. Therefore, for the purpose of brevity, the implementation method and technical effect of the closing detection method of the manual bypass air switch will not be repeated here.

[0147] The present application also provides a backup power system. Figure 1 and Figure 2 As shown, the backup power system includes: an inverter, and a grid-connected and off-grid controller as provided in the above embodiment.

[0148] The inverter is connected to the inverter-side INV port of the on-grid and off-grid controller, and the grid-side GRID port of the on-grid and off-grid controller is used to connect to the grid. The inverter is used to send a status indication signal to the on-grid and off-grid controller, and the status indication signal is used to indicate whether the inverter is in an operating state or a non-operating state.

[0149] Optionally, the inverter is also used to control its output effective voltage to be a first voltage and a second voltage in sequence according to a disturbance instruction sent by a grid-connected or off-grid controller when it is in operation, and the first voltage is different from the second voltage.

[0150] Optionally, the duration of the first voltage output by the inverter is a fourth duration, and the duration of the second voltage output by the inverter is a fifth duration.

[0151] In the embodiments of the present application, the terms "first", "second" and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The term "at least one" means one or more, and "plurality" means two or more.

[0152] The term "and / or" in this application is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0153] The above is only an optional implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A backup power system, characterized in that: The backup power system includes an inverter and an on-grid and off-grid controller; the inverter side port of the on-grid and off-grid controller is connected to the inverter, the grid side port of the on-grid and off-grid controller is used to connect to the grid, and the on-grid and off-grid controller includes: an on-grid and off-grid relay, a manual bypass air switch and a control circuit; Wherein, the on-grid and off-grid relay is connected between the inverter side port and the grid side port, the manual bypass air switch is connected between the inverter side port and the grid side port, and the control circuit is respectively connected to the inverter side port, the grid side port, the inverter and the on-grid and off-grid relay; The inverter is used to send a state indication signal to the control circuit, wherein the state indication signal is used to indicate whether the inverter is in an operating state or a non-operating state; The control circuit is used to detect the voltage of the inverter side port and the voltage of the grid side port. If, when the on-grid and off-grid relay is disconnected, the voltage of the inverter side port and the voltage of the grid side port are both greater than a first threshold, the voltage difference across the manual bypass air switch is less than a second threshold, and the inverter is in a non-operating state, an alarm signal is issued, and the alarm signal is used to indicate that the manual bypass air switch is in a closed state.

2. The backup power system according to claim 1, characterized in that: The control circuit is used to send an alarm signal if the voltage of the inverter side port and the voltage of the grid side port are both greater than a first threshold, the voltage difference across the manual bypass air switch is less than the second threshold for a first time period, and the inverter is in a non-operating state.

3. The backup power system according to claim 1 or 2, characterized in that: The control circuit is further used to control the on-grid relay to remain in an off state and send a shutdown command to the inverter according to the manual bypass air switch being in a closed state; The inverter is used to shut down according to the shutdown instruction.

4. The backup power system according to any one of claims 1 to 3, characterized in that: The inverter side port of the on-grid and off-grid controller is also used to connect to a backup power load, and the grid side port of the on-grid and off-grid controller is also used to connect to a non-backup power load.

5. The backup power system according to any one of claims 1 to 4, characterized in that: The first threshold is k1U n , the second threshold is k2U n ; Among them, U n is the rated voltage of the power grid, k1 is the first coefficient, k2 is the second coefficient, the value range of the second coefficient is 0.01 to 0.1, the first coefficient is greater than the first coefficient and less than 1.

6. A backup power system, characterized in that: The backup power system includes an inverter and an on-grid and off-grid controller; the inverter side port of the on-grid and off-grid controller is connected to the inverter, the grid side port of the on-grid and off-grid controller is used to connect to the grid, and the on-grid and off-grid controller includes: an on-grid and off-grid relay, a manual bypass air switch and a control circuit; Wherein, the on-grid and off-grid relay is connected between the inverter side port and the grid side port, the manual bypass air switch is connected between the inverter side port and the grid side port, and the control circuit is respectively connected to the inverter side port, the grid side port, the inverter and the on-grid and off-grid relay; The inverter is used to send a state indication signal to the control circuit, wherein the state indication signal is used to indicate whether the inverter is in an operating state or a non-operating state; The control circuit is used to detect the voltage of the inverter side port and the voltage of the grid side port, and when the on-grid relay is disconnected, if it is detected that the voltage of the inverter side port and the voltage of the grid side port are both greater than a first threshold value and the inverter is in a running state, a disturbance instruction is sent to the inverter; The inverter is further used to control the effective voltage outputted by the inverter to be a first voltage and a second voltage in sequence according to the disturbance instruction, wherein the first voltage is different from the second voltage; The control circuit is also used to detect the voltage difference across the manual bypass air switch after sending the disturbance instruction. If the voltage difference is less than a second threshold, an alarm signal is issued, and the alarm signal is used to indicate that the manual bypass air switch is in a closed state.

7. The backup power system according to claim 6, characterized in that: The control circuit is used to send the disturbance instruction to the inverter when the grid-connected and off-grid relay is disconnected, if it is detected that the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold, the voltage difference across the manual bypass air switch is less than the second threshold, and the inverter is in operation.

8. The backup power system according to claim 7, characterized in that: The control circuit is used for sending the disturbance instruction to the inverter when the on-grid and off-grid relay is disconnected, if it is detected that the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold, the voltage difference across the manual bypass air switch is less than the second threshold for a first time period, and the inverter is in operation.

9. The backup power system according to any one of claims 6 to 8, characterized in that: The control circuit is configured to send the alarm signal if it is detected that the voltage difference between the two ends of the manual bypass air switch is less than the second threshold value for a third time period within the second time period after the disturbance instruction is sent; Among them, the second duration is greater than the third duration.

10. The backup power system according to claim 9, characterized in that: The duration of the first voltage is a fourth duration, and the duration of the second voltage is a fifth duration; Among them, the third duration is greater than the fourth duration, and greater than the fifth duration.

11. The backup power system according to any one of claims 6 to 10, characterized in that: The first voltage is (1+k3)U n , the second voltage is (1-k3)U n ; Among them, U n is the rated voltage of the power grid, k3 is a third coefficient, and the third coefficient is greater than 0 and less than or equal to 0.

2.

12. The backup power system according to any one of claims 6 to 11, characterized in that: The control circuit is further used to control the on-grid relay to remain in an off state and send a shutdown command to the inverter according to the manual bypass air switch being in a closed state; The inverter is further configured to shut down according to the shutdown instruction.

13. The backup power system according to any one of claims 6 to 12, characterized in that: The inverter side port of the on-grid and off-grid controller is also used for connecting a backup power load, and the grid side port of the on-grid and off-grid controller is also used for a non-backup power load.

14. A method for detecting the closing of a manual bypass air switch, characterized in that: The method comprises: Detecting the voltage of the inverter side port of the on-grid and off-grid controller, the voltage of the grid side port and the operating status of the inverter; If, when the grid-connected and off-grid relay is disconnected, the voltage of the inverter side port and the voltage of the grid side port are both greater than the first threshold, the voltage difference across the manual bypass air switch is less than the second threshold, and the inverter is in a non-operating state, an alarm signal is issued, and the alarm signal is used to indicate that the manual bypass air switch is in a closed state.

15. A method for detecting the closing of a manual bypass air switch, characterized in that: The method comprises: Detecting the voltage of the inverter side port of the on-grid and off-grid controller, the voltage of the grid side port and the operating status of the inverter; When the on-grid and off-grid relay is disconnected, if it is detected that the voltage of the inverter side port and the voltage of the grid side port are both greater than a first threshold value, and the inverter is in operation, a disturbance instruction is sent to the inverter; The inverter controls the effective voltage outputted by the inverter according to the disturbance instruction to be a first voltage and a second voltage in sequence, and the first voltage is different from the second voltage; After sending the disturbance instruction, if it is detected that the voltage difference across the manual bypass air switch is less than the second threshold, an alarm signal is issued, wherein the alarm signal is used to indicate that the manual bypass air switch is in a closed state.

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