Grid-connected relay circuit, micro inverter system and energy storage equipment

Abstract

The utility model discloses a grid-connected relay circuit, a micro inverter system and an energy storage device. The micro inverter system comprises a power conversion circuit and a leakage protection circuit. The grid-connected relay circuit comprises a first live wire relay, a second live wire relay, a first null line relay, a second null line relay and a controller; the controller is connected with the power conversion circuit and each relay, and is used for controlling all the inverters to switch on and off states before grid connection of the micro inverter system; obtaining a first voltage difference value, a second voltage difference value and a third voltage difference value between the first port voltage of the power conversion circuit and the second port voltage of the electric leakage protection circuit; and determining a failure detection result of the grid-connected relay circuit according to the first voltage difference value, the second voltage difference value and the third voltage difference value. According to the invention, tripping of the leakage protection circuit can be avoided, and the micro inverter system can maintain normal operation.

Description

Technical Field

[0001] The present application relates to the field of database computing technology, and in particular to a grid-connected relay circuit, a micro-inverter system, and an energy storage device. Background Art

[0002] In existing micro-inverter systems, a leakage protection circuit is typically installed between the output side of the power conversion circuit and the mains power supply to prevent accidents caused by leakage from the mains power supply. A relay is also installed between the output side of the power conversion circuit and the leakage protection circuit. If this relay fails or short-circuits during startup of the micro-inverter system, the leakage protection circuit may trip, thus affecting the normal operation of the micro-inverter system. Utility Model Content

[0003] In view of this, the present application provides a grid-connected relay circuit, a micro-inverter system, and an energy storage device to prevent the leakage protection circuit from tripping and enable the micro-inverter system to maintain normal operation. The technical solution of the present application is as follows:

[0004] In a first aspect, the present application provides a grid-connected relay circuit, which is applied to a micro-inverter system. The micro-inverter system includes a power conversion circuit and a leakage protection circuit; the grid-connected relay circuit includes a first live wire relay, a second live wire relay, a first neutral wire relay, a second neutral wire relay and a controller; the first live wire port of the power conversion circuit is connected in series with the first live wire relay, the second live wire relay and the second live wire port of the leakage protection circuit, and the first neutral wire port of the power conversion circuit is connected in series with the first neutral wire relay, the second neutral wire relay and the second neutral wire port of the leakage protection circuit; the leakage protection circuit is also used to connect to a mains power grid; the controller is connected to the power conversion circuit and each relay, and the controller is used to: Before grid connection, all inverters are disconnected, and a first voltage difference between the first port voltage of the power conversion circuit and the second port voltage of the leakage protection circuit is obtained; the first live wire relay and the first neutral wire relay are controlled to be turned on, and a second voltage difference between the first port voltage of the power conversion circuit and the second port voltage of the leakage protection circuit is obtained; the first live wire relay and the first neutral wire relay are controlled to be disconnected, and the second live wire relay and the second neutral wire relay are controlled to be turned on, and a third voltage difference between the first port voltage of the power conversion circuit and the second port voltage of the leakage protection circuit is obtained; and a failure detection result of the grid-connected relay circuit is determined based on the first voltage difference, the second voltage difference, and the third voltage difference.

[0005] In one embodiment of the present application, the controller is also used to control the first live wire relay to be disconnected, and the second live wire relay, the first neutral wire relay and the second neutral wire relay to be turned on after determining that the grid-connected relay circuit is valid based on the failure detection result, and control the power conversion circuit to operate, and when the port voltage of the power conversion circuit is equal to the port voltage of the leakage protection circuit, control the first live wire relay to be turned on.

[0006] In one embodiment of the present application, a first voltage collector is further included, which is connected to the first live port and the first neutral port of the power conversion circuit. The first voltage collector is used to obtain the first port voltage between the live port and the neutral port of the power conversion circuit, and transmit the first port voltage to the controller.

[0007] In one embodiment of the present application, a second voltage collector is further included, which is connected to the second live wire port and the second neutral wire port of the leakage protection circuit. The second voltage collector is used to obtain the second port voltage between the second live wire port and the second neutral wire port of the leakage protection circuit, and transmit the second port voltage to the controller.

[0008] In an embodiment of the present application, the controller is further configured to determine that the second live relay and the second neutral relay are short-circuited when it is determined that the second voltage difference is not equal to the first voltage difference.

[0009] In an embodiment of the present application, the controller is further configured to determine that the first live relay and the first neutral relay are short-circuited when it is determined that the third voltage difference is not equal to the first voltage difference.

[0010] In one embodiment of the present application, the controller is further configured to determine that the grid-connected relay circuit has failed when the first voltage difference, the second voltage difference, and the third voltage difference are equal.

[0011] The second aspect of the present application provides a micro-inverter system, including a power conversion circuit, a leakage protection circuit and a grid-connected relay circuit, wherein the grid-connected relay circuit includes a first live wire relay, a second live wire relay, a first neutral wire relay, a second neutral wire relay and a controller; the first live wire port of the power conversion circuit is connected in series with the first live wire relay, the second live wire relay and the second live wire port of the leakage protection circuit, and the first neutral wire port of the power conversion circuit is connected in series with the first neutral wire relay, the second neutral wire relay and the second neutral wire port of the leakage protection circuit; the leakage protection circuit is also used to connect to the mains power grid; the controller is connected to the power conversion circuit and each relay, and the controller is used to: disconnect the micro-inverter system before it is connected to the grid all inverters, and obtain a first voltage difference between the first port voltage of the power conversion circuit and the second port voltage of the leakage protection circuit; control the first live wire relay and the first neutral wire relay to be turned on, and obtain a second voltage difference between the first port voltage of the power conversion circuit and the second port voltage of the leakage protection circuit; control the first live wire relay and the first neutral wire relay to be turned off, and the second live wire relay and the second neutral wire relay to be turned on, and obtain a third voltage difference between the first port voltage of the power conversion circuit and the second port voltage of the leakage protection circuit; determine the failure detection result of the grid-connected relay circuit according to the first voltage difference, the second voltage difference and the third voltage difference.

[0012] In one embodiment of the present application, a photovoltaic component is further included, wherein the photovoltaic component is connected to the power conversion circuit, and the photovoltaic component is used to output a DC voltage to the power conversion circuit.

[0013] A third aspect of the present application provides an energy storage device, including the micro-inverter system.

[0014] The power conversion circuit of the micro-inverter system in the present application is connected to the leakage protection circuit through a grid-connected relay circuit. Before the micro-inverter system is connected to the grid, the controller in the grid-connected relay circuit controls the disconnection of all inverters, obtains a first voltage difference between the port voltage of the power conversion circuit and the port voltage of the leakage protection circuit, then controls the first live wire relay and the first neutral wire relay to be turned on, and the second live wire relay and the second neutral wire relay to be turned off, obtains a second voltage difference between the port voltage of the power conversion circuit and the port voltage of the leakage protection circuit, then controls the first live wire relay and the first neutral wire relay to be turned off, and the second live wire relay and the second neutral wire relay to be turned on, obtains a third voltage difference between the port voltage of the power conversion circuit and the port voltage of the leakage protection circuit, and finally determines a failure detection result of the grid-connected relay circuit based on the first voltage difference, the second voltage difference, and the third voltage difference, so as to avoid the leakage protection circuit tripping due to failure of the grid-connected relay circuit, thereby affecting the normal operation of the micro-inverter system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic block diagram of a grid-connected relay circuit provided in an embodiment of the present application.

[0016] Figure 2 This is a schematic block diagram of another grid-connected relay circuit provided in an embodiment of the present application.

[0017] Figure 3 This is a schematic block diagram of a micro-inverter system provided in an embodiment of the present application.

[0018] Figure 4-11 This is a schematic block diagram of various states of relays in a micro-inverter system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0019] It should be noted that, in the embodiments of the present application, "at least one" refers to one or more, and "more than one" refers to two or more than two. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The terms "first", "second", "third", "fourth", etc. (if any) in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence.

[0020] It should also be noted that the method disclosed in the embodiments of the present application or the method shown in the flowchart includes one or more steps for implementing the method. Without departing from the scope of the claims, the execution order of multiple steps can be interchanged with each other, and some steps can also be deleted.

[0021] In existing micro-inverter systems, a leakage protection circuit is typically installed between the output side of the power conversion circuit and the mains power supply to prevent accidents caused by leakage from the mains power supply. A relay is also installed between the output side of the power conversion circuit and the leakage protection circuit. If this relay fails or short-circuits during startup of the micro-inverter system, the leakage protection circuit may trip, thus affecting the normal operation of the micro-inverter system.

[0022] The present application provides a grid-connected relay circuit, a micro-inverter system, and an energy storage device, which are used to prevent the leakage protection circuit from tripping and enable the micro-inverter system to maintain normal operation after startup.

[0023] Please refer to Figure 1 , Figure 1 This is a schematic block diagram of a grid-connected relay circuit provided in an embodiment of the present application, wherein the grid-connected relay circuit 100 is applied to a micro-inverter system 10 .

[0024] In an embodiment of the present application, a micro-inverter system 10 includes a power conversion circuit 101, a leakage protection circuit 102, and a grid-connected relay circuit 100 disposed between the power conversion circuit 101 and the leakage protection circuit 102. The grid-connected relay circuit 100 includes a first live relay 110, a second live relay 120, a first neutral relay 130, a second neutral relay 140, and a controller 150. The first live port of the power conversion circuit 101 is connected in series with the first live relay 110, the second live relay 120, and the second live port of the leakage protection circuit 102. The first neutral port of the power conversion circuit 101 is connected in series with the first neutral relay 130, the second neutral relay 140, and the second neutral port of the leakage protection circuit 102. The leakage protection circuit 102 is also configured to connect to a mains power grid. The leakage protection circuit 102 is configured to detect leakage faults in the micro-inverter system 10 and disconnect from the mains power grid when leakage occurs, thereby preventing overload or short circuits in the micro-inverter system 10.

[0025] In some embodiments, the leakage protection circuit 102 may be an RCD circuit (RCD, Residual Current Device), which is used to detect the current difference between the live wire and the neutral wire in the micro-inverter system 10. When the detected current difference exceeds a set value, the connection with the mains power grid is cut off.

[0026] In some embodiments, the power conversion circuit 101 is a three-phase inverter circuit including three first live ports and one first neutral port, and the leakage protection circuit 102 includes three second live ports and one second neutral port. Each first live port of the three-phase inverter circuit is connected in series with a first live relay 110, a second live relay 120, and one of the second live ports of the leakage protection circuit 102, respectively. Furthermore, the first neutral port of the three-phase inverter circuit is connected in series with a first neutral relay 130, a second neutral relay 140, and the second neutral port of the leakage protection circuit 102.

[0027] Among them, the controller 150 is connected to the power conversion circuit 101 and each relay. The controller 150 is used to: before the micro-inverter system 10 is connected to the grid, disconnect all inverters, and obtain a first voltage difference between the first port voltage of the power conversion circuit 101 and the second port voltage of the leakage protection circuit 102, control the first live wire relay 110 and the first neutral wire relay 130 to be turned on, and obtain a second voltage difference between the first port voltage of the power conversion circuit 101 and the second port voltage of the leakage protection circuit 102, control the first live wire relay 110 and the first neutral wire relay 130 to be turned off, and the second live wire relay 120 and the second neutral wire relay 140 to be turned on, obtain a third voltage difference between the first port voltage of the power conversion circuit 101 and the second port voltage of the leakage protection circuit 102, and determine the failure detection result of the grid-connected relay circuit according to the first voltage difference, the second voltage difference and the third voltage difference.

[0028] It can be understood that the power conversion circuit 101 of the micro-inverter system 10 in the present application is connected to the leakage protection circuit 102 through the grid-connected relay circuit 100. Before the micro-inverter system 10 is connected to the grid, the controller 150 in the grid-connected relay circuit 100 controls to disconnect all inverters, obtains the first voltage difference between the port voltage of the power conversion circuit 101 and the port voltage of the leakage protection circuit 102, and then controls the first live wire relay 110 and the first neutral wire relay 130 to be turned on, and the second live wire relay 120 and the second neutral wire relay 140 to be turned off, and obtains the port voltage of the power conversion circuit 101. The first live wire relay 110 and the first neutral wire relay 130 are then controlled to be disconnected, and the second live wire relay 120 and the second neutral wire relay 140 are controlled to be turned on, so as to obtain a third voltage difference between the port voltage of the power conversion circuit 101 and the port voltage of the leakage protection circuit 102. Finally, a failure detection result of the grid-connected relay circuit is determined according to the first voltage difference, the second voltage difference, and the third voltage difference, so as to avoid the leakage protection circuit 102 tripping due to the failure of the grid-connected relay circuit 100, thereby affecting the normal operation of the micro-inverter system 10.

[0029] In some embodiments, the controller 150 is also used to control the first live wire relay 110 to be disconnected, and the second live wire relay 120, the first neutral wire relay 130 and the second neutral wire relay 140 to be turned on after determining that the grid-connected relay circuit 100 is valid based on the failure detection result, and to control the power conversion circuit 101 to operate. When the port voltage of the power conversion circuit 101 is equal to the port voltage of the leakage protection circuit 102, the first live wire relay 110 is controlled to be turned on.

[0030] In some embodiments, as Figure 2 As shown, the grid-connected relay circuit 100 also includes a first voltage collector 160, which is connected to the first live wire port and the first neutral wire port of the power conversion circuit 101. The first voltage collector 160 is used to obtain the first port voltage between the live wire port and the neutral wire port of the power conversion circuit 101, and transmit the first port voltage to the controller 150.

[0031] The grid-connected relay circuit 100 also includes a second voltage collector 170, which is connected to the second live wire port and the second neutral wire port of the leakage protection circuit 102. The second voltage collector 170 is used to obtain the second port voltage between the second live wire port and the second neutral wire port of the leakage protection circuit 102, and transmit the second port voltage to the controller 150.

[0032] Among them, when the power conversion circuit 101 is the above-mentioned three-phase inverter circuit, that is, the three-phase inverter circuit includes three first live wire ports and one first neutral wire port, and the leakage protection circuit 102 includes three second live wire ports and one second neutral wire port, then a first voltage collector 160 is provided between each first live wire port and the first neutral wire port, and a second voltage collector 170 is provided between each second live wire port and the second neutral wire port.

[0033] In some embodiments, the controller 150 is further configured to determine that the second live relay 120 and the second neutral relay 140 are short-circuited when it is determined that the second voltage difference is not equal to the first voltage difference.

[0034] It can be understood that when the second voltage difference is equal to the first voltage difference, there are four possibilities: (1) the first live wire relay 110 and the first neutral wire relay 130 can be controlled to be turned on, and the second live wire relay 120 and the second neutral wire relay 140 can be controlled to be turned off; (2) the first live wire relay 110 and the first neutral wire relay 130 can be controlled to be turned on, and the second live wire relay 120 and the second neutral wire relay 140 cannot be controlled to be turned on, such as Figure 4 (3) the first live wire relay 110, the second live wire relay 120, the first neutral wire relay 130 and the second neutral wire relay 140 cannot be controlled to be turned on, as shown in FIG. Figure 5 (4) the first live relay 110 and the first neutral relay 130 cannot be controlled to be turned on, and the second live relay 120 and the second neutral relay 140 are in a short-circuit state, as shown. Figure 6 When the second voltage difference is not equal to the first voltage difference, it means: (1) the first live wire relay 110 and the first neutral wire relay 130 can be controlled to be turned on, and the second live wire relay 120 and the second neutral wire relay 140 are in a short-circuit state, as shown in FIG. Figure 7 (2) the first live wire relay 110, the second live wire relay 120, the first neutral wire relay 130 and the second neutral wire relay 140 are all in a short circuit state, as shown in FIG. Figure 8 shown.

[0035] In some embodiments, the controller 150 is further configured to determine that the first live relay 110 and the first neutral relay 130 are short-circuited when it is determined that the third voltage difference is not equal to the first voltage difference.

[0036] It can be understood that when the third voltage difference is equal to the first voltage difference, there are four possibilities: (1) the first live wire relay 110 and the first neutral wire relay 130 can be controlled to be disconnected, and the second live wire relay 120 and the second neutral wire relay 140 can be controlled to be turned on; (2) the first live wire relay 110 and the first neutral wire relay 130 cannot be controlled to be turned on, and the second live wire relay 120 and the second neutral wire relay 140 can be controlled to be turned on, as shown in FIG. Figure 9 (3) the first live wire relay 110, the second live wire relay 120, the first neutral wire relay 130 and the second neutral wire relay 140 cannot be controlled to be turned on, as shown Figure 5 (4) the first live relay 110 and the first neutral relay 130 are in a short-circuit state, and the second live relay 120 and the second neutral relay 140 cannot be controlled to be turned on, as shown in FIG. Figure 10 When the third voltage difference is not equal to the first voltage difference, it means: (1) the first live wire relay 110 and the first neutral wire relay 130 are in a short-circuit state, and the second live wire relay 120 and the second neutral wire relay 140 can be controlled to be turned on, as shown in FIG. Figure 11 (2) the first live wire relay 110, the second live wire relay 120, the first neutral wire relay 130 and the second neutral wire relay 140 are all in a short circuit state, as shown in FIG. Figure 8 shown.

[0037] In some embodiments, the controller 150 is further configured to determine that the grid-connected relay circuit 100 has failed when the first voltage difference, the second voltage difference, and the third voltage difference are equal.

[0038] Please refer to Figure 3 , Figure 3 The micro-inverter system 300 includes a power conversion circuit 310 , a leakage protection circuit 320 , and a grid-connected relay circuit 330 .

[0039] Among them, the grid-connected relay circuit 330 includes a first live wire relay 331, a second live wire relay 332, a first neutral wire relay 333, a second neutral wire relay 334 and a controller 335; the first live wire port of the power conversion circuit 310 is connected in series with the first live wire relay 331, the second live wire relay 332 and the second live wire port of the leakage protection circuit 320, and the first neutral wire port of the power conversion circuit 310 is connected in series with the first neutral wire relay 333, the second neutral wire relay 334 and the second neutral wire port of the leakage protection circuit 320; the leakage protection circuit 320 is also used to connect to the mains power grid.

[0040] In an embodiment of the present application, the controller 335 is connected to the power conversion circuit 310 and each relay. The controller 335 is used to: before the micro-inverter system 300 is connected to the grid, disconnect all inverters, and obtain a first voltage difference between the first port voltage of the power conversion circuit 310 and the second port voltage of the leakage protection circuit 320, control the first live wire relay 331 and the first neutral wire relay 333 to be turned on, and obtain a second voltage difference between the first port voltage of the power conversion circuit 310 and the second port voltage of the leakage protection circuit 320, control the first live wire relay 331 and the first neutral wire relay 333 to be disconnected, and the second live wire relay 332 and the second neutral wire relay 334 to be turned on, obtain a third voltage difference between the first port voltage of the power conversion circuit 310 and the second port voltage of the leakage protection circuit 320, and determine the failure detection result of the grid-connected relay circuit according to the first voltage difference, the second voltage difference and the third voltage difference.

[0041] The micro-inverter system 300 further includes a photovoltaic module 340 . The photovoltaic module 340 is connected to the power conversion circuit 310 . The photovoltaic module 340 is configured to output a DC voltage to the power conversion circuit 310 .

[0042] An embodiment of the present application further provides an energy storage device, comprising the micro-inverter system of any of the above embodiments.

[0043] It can be understood that the beneficial effects of the above-mentioned micro-inverter system and energy storage device can refer to the beneficial effects of the aforementioned grid-connected relay circuit, and will not be repeated here.

[0044] The embodiments described above are merely preferred embodiments of the present application and are not intended to limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements made to the technical solutions of the present application by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present application.

Claims

1. A grid-connected relay circuit, characterized in that: Applicable to a micro-inverter system, the micro-inverter system including a power conversion circuit and a leakage protection circuit; The grid-connected relay circuit includes a first live wire relay, a second live wire relay, a first neutral wire relay, a second neutral wire relay, and a controller; the first live wire port of the power conversion circuit is connected in series with the first live wire relay, the second live wire relay, and the second live wire port of the leakage protection circuit; the first neutral wire port of the power conversion circuit is connected in series with the first neutral wire relay, the second neutral wire relay, and the second neutral wire port of the leakage protection circuit; the leakage protection circuit is also used to connect to the mains power grid; The controller is connected to the power conversion circuit and each relay, and is used for: Before the micro-inverter system is connected to the grid, all inverters are disconnected, and a first voltage difference between a first port voltage of the power conversion circuit and a second port voltage of the leakage protection circuit is obtained; Controlling the first live line relay and the first neutral line relay to be turned on, and obtaining a second voltage difference between the first port voltage of the power conversion circuit and the second port voltage of the leakage protection circuit; Controlling the first live relay and the first neutral relay to be disconnected and the second live relay and the second neutral relay to be connected, and obtaining a third voltage difference between the first port voltage of the power conversion circuit and the second port voltage of the leakage protection circuit; A failure detection result of the grid-connected relay circuit is determined according to the first voltage difference, the second voltage difference, and the third voltage difference.

2. The grid-connected relay circuit according to claim 1, characterized in that: The controller is further configured to control the first live wire relay to be disconnected and the second live wire relay, the first neutral wire relay, and the second neutral wire relay to be turned on after determining that the grid-connected relay circuit is valid based on a failure detection result, and to control the power conversion circuit to operate, and to control the first live wire relay to be turned on when the port voltage of the power conversion circuit is equal to the port voltage of the leakage protection circuit.

3. The grid-connected relay circuit according to claim 1, characterized in that: It also includes a first voltage collector, which is connected to the first live port and the first neutral port of the power conversion circuit. The first voltage collector is used to obtain the first port voltage between the live port and the neutral port of the power conversion circuit and transmit the first port voltage to the controller.

4. The grid-connected relay circuit according to claim 1, characterized in that: It also includes a second voltage collector, which is connected to the second live wire port and the second neutral wire port of the leakage protection circuit. The second voltage collector is used to obtain the second port voltage between the second live wire port and the second neutral wire port of the leakage protection circuit, and transmit the second port voltage to the controller.

5. The grid-connected relay circuit according to claim 1, characterized in that: The controller is further configured to determine that the second live relay and the second neutral relay are short-circuited when it is determined that the second voltage difference is not equal to the first voltage difference.

6. The grid-connected relay circuit according to claim 1, characterized in that: The controller is further configured to determine that the first live relay and the first neutral relay are short-circuited when it is determined that the third voltage difference is not equal to the first voltage difference.

7. The grid-connected relay circuit according to claim 1, characterized in that: The controller is further configured to determine that the grid-connected relay circuit has failed when the first voltage difference, the second voltage difference, and the third voltage difference are equal.

8. A micro-inverter system, characterized in that: The invention comprises a power conversion circuit, a leakage protection circuit and a grid-connected relay circuit, wherein the grid-connected relay circuit comprises a first live wire relay, a second live wire relay, a first neutral wire relay, a second neutral wire relay and a controller; the first live wire port of the power conversion circuit is connected in series with the first live wire relay, the second live wire relay and the second live wire port of the leakage protection circuit, and the first neutral wire port of the power conversion circuit is connected in series with the first neutral wire relay, the second neutral wire relay and the second neutral wire port of the leakage protection circuit; the leakage protection circuit is also used to connect to the mains power grid; The controller is connected to the power conversion circuit and each relay, and is used for: Before the micro-inverter system is connected to the grid, all inverters are disconnected, and a first voltage difference between a first port voltage of the power conversion circuit and a second port voltage of the leakage protection circuit is obtained; Controlling the first live line relay and the first neutral line relay to be turned on, and obtaining a second voltage difference between the first port voltage of the power conversion circuit and the second port voltage of the leakage protection circuit; Controlling the first live relay and the first neutral relay to be disconnected and the second live relay and the second neutral relay to be connected, and obtaining a third voltage difference between the first port voltage of the power conversion circuit and the second port voltage of the leakage protection circuit; A failure detection result of the grid-connected relay circuit is determined according to the first voltage difference, the second voltage difference, and the third voltage difference.

9. The micro-inverter system according to claim 8, characterized in that: It also includes a photovoltaic component, which is connected to the power conversion circuit and is used to output a DC voltage to the power conversion circuit.

10. An energy storage device, characterized in that: The micro-inverter system comprises the micro-inverter system as claimed in claim 8 or 9.

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