Leakage current protection system

Abstract

The utility model provides a leakage current protection system, comprising at least one leakage current protection subsystem, each leakage current protection subsystem comprising a photovoltaic unit, a leakage current protection module and an inverter; the leakage current protection module comprises at least two leakage current protection sub-modules, and the positive electrode of the photovoltaic unit is electrically connected with the positive electrode of the corresponding inverter through at least one leakage current protection sub-module arranged on the DC positive electrode. The negative electrode of the photovoltaic unit is electrically connected with the negative electrode of the corresponding inverter through at least one leakage current protection sub-module arranged on the direct current negative electrode; the photovoltaic unit is used for generating direct current; the inverter is used for converting the direct current into alternating current; and the leakage current protection module is used for judging whether the leakage current on the direct current positive electrode and the direct current negative electrode suddenly changes or not, and increasing the impedance in the corresponding leakage current loop when the leakage current suddenly changes. According to the utility model, the influence of leakage current protection on the normal operation of the leakage current protection subsystem can be reduced.

Description

Technical Field

[0001] The utility model relates to the field of electrical technology, in particular to a leakage current protection system. Background Art

[0002] Photovoltaic power generation systems usually include photovoltaic units and inverters. The inverter converts the direct current generated by the photovoltaic unit into alternating current and provides it to the power grid. During the power generation process of the photovoltaic power generation system, if the human body accidentally touches the leakage current, it will pose a great safety threat to the human body. Therefore, how to reduce the amount of leakage current passing through the human body when the human body is accidentally electrocuted is the key to leakage current protection design.

[0003] The existing technology usually protects people from electric shock by disconnecting the connection switch between the inverter and the transformer. This method requires cutting off the power supply of the inverter to the grid and then re-supplying power to the grid after eliminating the safety hazards. This leakage current protection method has a huge impact on the normal operation of the photovoltaic power generation system. Utility Model Content

[0004] In view of this, an object of the present invention is to provide a leakage current protection system to reduce the influence of leakage current protection on the normal operation of the leakage current protection subsystem.

[0005] An embodiment of the utility model provides a leakage current protection system, comprising: at least one leakage current protection subsystem, each leakage current protection subsystem comprising a photovoltaic unit, a leakage current protection module and an inverter; wherein the leakage current protection module comprises at least two leakage current protection submodules, the positive pole of the photovoltaic unit is electrically connected to the positive pole of the corresponding inverter through at least one leakage current protection submodule arranged on the DC positive pole, and the negative pole of the photovoltaic unit is electrically connected to the negative pole of the corresponding inverter through at least one leakage current protection submodule arranged on the DC negative pole; the photovoltaic unit is used to generate direct current; the inverter is used to convert the direct current into alternating current; the leakage current protection module is used to determine whether a sudden change occurs in the leakage current on the DC positive pole and the DC negative pole, and to increase the impedance in the corresponding leakage current loop when a sudden change occurs in the leakage current.

[0006] In a feasible embodiment, each leakage current protection submodule includes at least one leakage current protection unit and a leakage current judgment unit; one end of the leakage current protection unit is electrically connected to an output end of the corresponding photovoltaic unit, one end of the leakage current judgment unit is electrically connected to an input end of the corresponding inverter, and the other end of the leakage current protection unit is electrically connected to the other end of the leakage current judgment unit; the leakage current judgment unit is used to judge whether the leakage current in the corresponding leakage current loop suddenly changes; the leakage current protection unit is used to increase the impedance in the corresponding leakage current loop when the leakage current in the corresponding leakage current loop suddenly changes.

[0007] In a feasible embodiment, each leakage current protection unit includes at least one path switch unit, at least one leakage current protection switch unit and at least one blocking device; one end of the path switch unit is electrically connected to an output end of the corresponding photovoltaic unit, and the other end of the path switch unit is electrically connected to one end of the corresponding leakage current judgment unit; one end of the leakage current protection switch unit is electrically connected to an output end of the corresponding photovoltaic unit, and the other end of the leakage current protection switch unit is electrically connected to one end of the corresponding blocking device, and the other end of the corresponding blocking device is electrically connected to one end of the corresponding leakage current judgment unit; the blocking device is used to increase the impedance in the corresponding leakage current loop.

[0008] In a feasible implementation manner, the leakage current protection switch unit and the path switch unit are controllable switch units, and the leakage current protection switch unit and the path switch unit include a communication unit; the communication unit is used to communicate with a switch control unit.

[0009] In a feasible implementation manner, the controllable switch unit is a semiconductor device type or a mechanical type switch.

[0010] In a feasible implementation manner, the inverter includes a switch control unit, and the switch control unit is used to control the closing and opening of the leakage current protection switch unit and the path switch unit in the leakage current protection unit.

[0011] In a feasible implementation manner, the blocking device includes at least one resistor.

[0012] In a feasible implementation manner, the leakage current judgment unit is a leakage current sensor.

[0013] In a feasible implementation manner, it further includes: a transformer and a first switch group; the transformer is used to output the alternating current; the first switch group is used to close or disconnect the electrical connection between the inverter and the transformer.

[0014] In a feasible implementation manner, when the number of the leakage current protection subsystem is one, the neutral point of the transformer output end is grounded; when the number of the leakage current protection subsystem is greater than one, the neutral point of the transformer output end is not grounded.

[0015] The technical solution provided by the utility model includes: at least one leakage current protection subsystem, each leakage current protection subsystem includes a photovoltaic unit, a leakage current protection module and an inverter; wherein the leakage current protection module includes at least two leakage current protection submodules, the positive pole of the photovoltaic unit is electrically connected to the positive pole of the corresponding inverter through at least one leakage current protection submodule arranged on the DC positive pole, and the negative pole of the photovoltaic unit is electrically connected to the negative pole of the corresponding inverter through at least one leakage current protection submodule arranged on the DC negative pole; the photovoltaic unit is used to generate direct current; the inverter is used to convert the direct current into alternating current; the leakage current protection module is used to determine whether the leakage current on the DC positive pole and the DC negative pole has a sudden change, and increase the impedance in the corresponding leakage current loop when the leakage current has a sudden change. In the utility model, the leakage current protection module in the leakage current protection subsystem is used to determine whether a sudden change occurs in the leakage current on the DC positive pole and the DC negative pole of the photovoltaic unit. If a sudden change occurs, the impedance in the corresponding leakage current loop is increased. Therefore, there is no need to cut off the AC power supply to the photovoltaic power generation system. At the same time, the leakage current can be prevented from causing harm to the human body, thereby reducing the impact of the leakage current protection on the normal operation of the photovoltaic power generation system.

[0016] Other features and advantages of the utility model will be described in the following description, and partly become apparent from the description, or understood by practicing the utility model. The purpose and other advantages of the utility model are realized and obtained by the structures specifically pointed out in the description, claims and drawings.

[0017] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are some implementation methods of the utility model. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 A schematic diagram of the structure of the leakage current protection system in the embodiment of the utility model;

[0020] Figure 2 Another structural schematic diagram of the leakage current protection system in the embodiment of the utility model;

[0021] Figure 3 Another structural schematic diagram of the leakage current protection system in the embodiment of the utility model;

[0022] Figure 4 Another structural schematic diagram of the leakage current protection system in the embodiment of the utility model;

[0023] Figure 5 Another structural schematic diagram of the leakage current protection system in the embodiment of the utility model;

[0024] Figure 6 Another structural schematic diagram of the leakage current protection system in the embodiment of the utility model;

[0025] Figure 7 It is another structural schematic diagram of the leakage current protection system in the embodiment of the utility model. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the utility model clearer, the technical solution of the utility model will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0027] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present utility model and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "including" or "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0028] See also Figure 1 , the embodiment of the utility model provides a leakage current protection system, specifically comprising: at least one leakage current protection subsystem 10, each leakage current protection subsystem 10 comprises a photovoltaic unit 101, a leakage current protection module 102 and an inverter 103;

[0029] The leakage current protection module 102 includes at least two leakage current protection submodules 1021, the positive pole of the photovoltaic unit is electrically connected to the positive pole of the corresponding inverter 103 through at least one leakage current protection submodule 1021 arranged on the DC positive pole, and the negative pole of the photovoltaic unit 101 is electrically connected to the negative pole of the corresponding inverter 103 through at least one leakage current protection submodule 1021 arranged on the DC negative pole;

[0030] Photovoltaic unit 101, for generating direct current;

[0031] An inverter 103, used to convert direct current into alternating current;

[0032] The leakage current protection module 102 is used to determine whether the leakage current on the DC positive electrode and the DC negative electrode has a sudden change, and to increase the impedance in the corresponding leakage current loop when the leakage current has a sudden change.

[0033] In the utility model, the leakage current protection module 102 in the leakage current protection subsystem 10 determines whether a sudden change occurs in the leakage current on the DC positive pole and the DC negative pole of the photovoltaic unit 101. If a sudden change occurs, the impedance in the corresponding leakage current loop is increased. Therefore, there is no need to cut off the power supply of the inverter to the power grid. At the same time, the leakage current can be prevented from causing harm to the human body, thereby reducing the impact of the leakage current protection on the normal operation of the photovoltaic power generation system.

[0034] It can be understood that when a human body is electrocuted, the human body can be equivalent to a resistor R. If the human body is electrocuted through the DC positive pole of the photovoltaic unit 101, it is equivalent to connecting the DC positive pole to the equivalent resistor R. If the human body is electrocuted through the DC negative pole of the photovoltaic unit 101, it is equivalent to connecting the DC negative pole to the equivalent resistor R. Regardless of whether the human body is electrocuted through the DC positive pole or the DC negative pole of the photovoltaic unit 101, a corresponding leakage current loop will be formed. Due to the connection of the equivalent resistor R, the leakage current in the leakage current loop suddenly changes. At this time, the leakage current protection module 102 detects that the leakage current in the corresponding leakage current loop suddenly changes, increases the impedance in the corresponding leakage current loop, thereby reducing the leakage current in the leakage current loop, and reducing the current flowing through the human body, thereby achieving the effect of leakage current protection.

[0035] It should be noted that a photovoltaic unit is a whole composed of photovoltaic modules. A photovoltaic unit can be a photovoltaic string, a photovoltaic array, or other combinations of photovoltaic modules, which are not specifically limited here.

[0036] In a feasible implementation, the leakage current protection module 102 can also be used to increase the impedance in the corresponding leakage current loop to a specified impedance value, so as to adapt to the leakage current protection of different leakage current protection systems. It is understandable that by increasing the impedance in the leakage current loop to a specified impedance value, the current flowing through the human body can be controlled to be less than a preset safety current value, thereby achieving the effect of leakage current protection. For example, the preset safety current value can be 0.5 mA, which is not specifically limited here.

[0037] In a feasible embodiment, each leakage current protection submodule 1021 includes at least one leakage current protection unit 10211 and at least one leakage current judgment unit 10212; one end of the leakage current protection unit 10211 is electrically connected to an output end of the corresponding photovoltaic unit 101, one end of the leakage current judgment unit 10212 is electrically connected to an input end of the corresponding inverter 103, and the other end of the leakage current protection unit 10211 is electrically connected to the other end of the leakage current judgment unit 10212; the leakage current judgment unit 10212 is used to judge whether the leakage current in the corresponding leakage current loop suddenly changes; the leakage current protection unit 10211 is used to increase the impedance in the corresponding leakage current loop when the leakage current in the corresponding leakage current loop suddenly changes. When there are more than one leakage current protection submodule 1021 on the DC positive pole / DC negative pole, the leakage current protection submodules 1021 on the same bus can be connected in series or in parallel, which is not limited here; when there are more than one leakage current protection unit 10211 and / or leakage current judgment unit 10212 in the leakage current protection submodule 1021, the leakage current protection unit 10211 can be electrically connected to the leakage current judgment unit 10212, or can be electrically connected to another leakage current protection unit 10211, which is not limited here.

[0038] like Figure 2As shown, taking each leakage current protection submodule 1021 including a leakage current protection unit 10211 and a leakage current judgment unit 10212 as an example for explanation, in this embodiment, a leakage current protection submodule 1021 is provided on both the DC positive pole and the DC negative pole of the photovoltaic unit 101, and for at least one leakage current protection submodule 1021 on the DC positive pole, one end of the leakage current protection unit 10211 in the leakage current protection submodule 1021 is electrically connected to the positive pole of the corresponding photovoltaic unit 101, and the other end of the leakage current protection unit 10211 in the leakage current protection submodule 1021 is electrically connected to one end of the leakage current judgment unit 10212 in the leakage current protection submodule 1021, and the leakage current protection unit 10211 in the leakage current protection submodule 1021 is electrically connected to the leakage current protection unit 10212 in the leakage current protection submodule 1021. The other end of the leakage current judgment unit 10212 in the leakage current protection submodule 1021 is electrically connected to the input end of the corresponding inverter 103; similarly, for at least one leakage current protection submodule 1021 on the DC positive pole, one end of the leakage current protection unit 10211 in the leakage current protection submodule 1021 is electrically connected to the negative pole of the corresponding photovoltaic unit 101, and the other end of the leakage current protection unit 10211 in the leakage current protection submodule 1021 is electrically connected to one end of the leakage current judgment unit 10212 in the leakage current protection submodule 1021, and the other end of the leakage current judgment unit 10212 in the leakage current protection submodule 1021 is electrically connected to the input end of the corresponding inverter 103. By using the leakage current judgment unit 10212 in at least one leakage current protection submodule 1021 arranged on the DC positive pole or the DC negative pole, it is judged whether the leakage current in the corresponding leakage current loop has a sudden change. If a human body is electrocuted through the DC positive pole or the DC negative pole of the photovoltaic unit 101, the leakage current protection unit 10211 in at least one leakage current protection submodule 1021 arranged on the DC positive pole or the DC negative pole increases the impedance in the corresponding leakage current loop to reduce the leakage current in the leakage current loop, reduce the current flowing through the human body, and achieve the effect of leakage current protection.

[0039] In a feasible implementation manner, the leakage current determination unit 10212 may also be disposed inside the corresponding inverter 103 , which is not specifically limited herein.

[0040] In a feasible embodiment, each leakage current protection unit 10211 includes at least one path switch unit, at least one leakage current protection switch unit and at least one blocking device; one end of the path switch unit is electrically connected to an output end of the corresponding photovoltaic unit 101, and the other end of the path switch unit is electrically connected to one end of the corresponding leakage current judgment unit 10212; one end of the leakage current protection switch unit is electrically connected to an output end of the corresponding photovoltaic unit 101, the other end of the leakage current protection switch unit is electrically connected to one end of the corresponding blocking device, and the other end of the corresponding blocking device is electrically connected to one end of the corresponding leakage current judgment unit 10212; the blocking device is used to increase the impedance in the corresponding leakage current loop.

[0041] like Figure 3 As shown, taking the example that each leakage current protection unit 10211 includes a path switch unit, a leakage current protection switch unit and a blocking device, the leakage current protection unit 10211 on the DC positive pole of the photovoltaic unit 101 includes a path switch unit S1, a leakage current protection switch unit S3 and a blocking device Q1, wherein one end of the path switch unit S1 is electrically connected to the positive pole of the photovoltaic unit, and the other end is electrically connected to the leakage current judgment unit 10212, the leakage current protection switch unit S3 and the blocking device Q1 are connected in series and then connected in parallel with the path switch unit S1, when the leakage current judgment unit 10212 detects a sudden change in the leakage current value in the corresponding leakage current loop, the path switch unit S1 is disconnected and the leakage current protection switch unit S3 is closed, so that the blocking device Q1 can be connected, so that the impedance on the positive pole path of the photovoltaic unit 101 is increased.

[0042] For ease of understanding, if a human body is electrocuted through the DC positive electrode of the photovoltaic unit 101, it is equivalent to connecting an equivalent resistor R1 to the DC positive electrode. Figure 4 The figure shows the schematic diagram of the leakage current loop corresponding to the positive electrode. Figure 4 It can be seen that due to the connection of the blocking device Q1, the impedance in the leakage current loop corresponding to the positive electrode increases, the leakage current decreases, and the leakage current flowing through the equivalent resistor R1 decreases, that is, the leakage current flowing through the human body decreases, which has an electric shock protection effect on the human body.

[0043] Similarly, if Figure 3As shown, the leakage current protection unit 10211 on the DC negative pole of the photovoltaic unit 101 includes a path switch unit S2, a leakage current protection switch unit S4 and a blocking device Q2, wherein one end of the path switch unit S2 is electrically connected to the negative pole of the photovoltaic unit 101, and the other end is electrically connected to the leakage current judgment unit 10212, the leakage current protection switch unit S4 and the blocking device Q2 are connected in series and then connected in parallel with the path switch unit S2, when the leakage current judgment unit 10212 detects that the leakage current value in the corresponding leakage current loop has a sudden change, the path switch unit S2 is disconnected, and the leakage current protection switch unit S4 is closed, so that the blocking device Q2 is connected, so that the impedance on the negative pole path of the photovoltaic unit 101 is increased.

[0044] For ease of understanding, if a human body is electrocuted through the negative DC pole of the photovoltaic unit 101, it is equivalent to connecting an equivalent resistor R2 to the negative DC pole. Figure 5 The figure shows a schematic diagram of the leakage current loop corresponding to the negative electrode. Due to the connection of the blocking device Q2, the impedance in the leakage current loop corresponding to the negative electrode increases, the leakage current decreases, and the leakage current flowing through the equivalent resistor R2 decreases, that is, the leakage current flowing through the human body decreases, which has an electric shock protection effect on the human body.

[0045] It can be understood that if the leakage current judgment unit 10212 on the DC positive pole detects that the leakage current in the leakage current loop corresponding to the positive pole of the photovoltaic unit 101 has not undergone a sudden change, and the leakage current judgment unit 10212 on the DC negative pole detects that the leakage current in the leakage current loop corresponding to the negative pole of the photovoltaic unit 101 has not undergone a sudden change, then the path switch unit S1 and the path switch unit S2 remain closed, the leakage current protection switch unit S3 and the leakage current protection switch unit S4 remain disconnected, so that the impedance in the circuit for converting DC power to AC power is within a normal range.

[0046] The following description is made by taking a leakage current protection system including two leakage current protection subsystems 10 as an example. Figure 6 As shown, for a leakage current protection system including more than one leakage current protection subsystem 10, the output end of the inverter 103 in each leakage current protection subsystem 10 can be connected to the leakage current protection subsystem 10, and a parallel connection relationship is formed between different leakage current protection subsystems 10, which can facilitate the connection of multiple photovoltaic units.

[0047] In a feasible implementation, the leakage current protection switch unit and the path switch unit are controllable switch units, and the leakage current protection switch unit and the path switch unit include a communication unit; the communication unit is used to communicate with the switch control unit. The connection and disconnection control of the leakage current protection switch unit and the path switch unit needs to be based on the leakage current judgment result of the leakage current judgment unit 10212. Therefore, the switch control unit can be set in the leakage current judgment unit 10212, and according to the leakage current judgment result (i.e., whether the leakage current on the DC positive pole and the DC negative pole suddenly changes), the switch control unit sends a control instruction to the communication unit of the leakage current protection switch unit and the path switch unit to achieve the purpose of switch switching.

[0048] In a feasible implementation, the controllable switch unit is a switch of semiconductor device type or mechanical type. The semiconductor device type includes but is not limited to field effect transistor, insulated gate transistor, gate turn-off thyristor, power transistor and other semiconductor device types, and the mechanical type includes but is not limited to circuit, relay or circuit breaker and other mechanical switch types.

[0049] In a feasible implementation, the inverter 103 includes a switch control unit, which is used to control the closing and opening of the leakage current protection switch unit and the path switch unit in the leakage current protection unit 10211. The switch control unit can be arranged inside the inverter 103, and the switch control unit inside the inverter 103 sends a control instruction to the communication unit of the leakage current protection switch unit and the path switch unit to achieve the purpose of switching.

[0050] In a feasible implementation, the blocking device includes at least one resistor. The blocking device can be at least one resistor or a circuit including at least one resistor, so as to increase the resistance in the leakage current loop and play a protective role in case of leakage.

[0051] In a feasible implementation, the leakage current determination unit 10212 is a leakage current sensor. A leakage current sensor is a sensor used to detect leakage current in a circuit. The leakage current sensor is usually based on the principle of current transformers. The current in the circuit is introduced into the coil inside the sensor for detection. When leakage current flows through the circuit, the coil inside the sensor senses the leakage current and generates a corresponding output signal to indicate whether the leakage current has a sudden change.

[0052] In a feasible implementation, the leakage current protection system further includes: a transformer 105 and a first switch group 104; the transformer 105 is used to output alternating current; and the first switch group 104 is used to close or disconnect the electrical connection between the inverter 103 and the transformer 105. To facilitate the use of alternating current, the leakage current protection system may further include a transformer 105 and a first switch group 104, wherein the first switch group 104 is used to close or disconnect the electrical connection between the output ends of the inverter 103 in each leakage current protection subsystem 10, and when the first switch group 104 is closed, the output end of the inverter 103 in each leakage current protection subsystem 10 is electrically connected to the transformer 105, and when the first switch group 104 is disconnected, the electrical connection between the inverter 103 in each leakage current protection subsystem 10 and the transformer 105 is disconnected.

[0053] In this embodiment, the AC power output by the transformer 105 can be used to supply power to the power grid. The first switch group 104 can be used to conveniently control whether the AC power flows to the power grid. The first switch group 104 can be used as a power switch for the photovoltaic power generation system. It should be noted that regardless of whether the leakage current on the DC positive pole and the DC negative pole changes suddenly, the first switch group 104 can remain closed, that is, the closing or disconnection of the first switch group 104 has nothing to do with whether the leakage current changes suddenly, that is, there is no need to cut off the power supply of the photovoltaic power generation system to the power grid, and the leakage current can be prevented from causing harm to the human body, so that the leakage current protection has a reduced impact on the normal operation of the photovoltaic power generation system and the power grid. Usually, when the photovoltaic power generation system or the power grid needs to be repaired, the first switch group 104 can be disconnected to stop the photovoltaic power generation system from supplying power to the power grid for maintenance.

[0054] For ease of understanding, Figure 7 The figure shows a schematic diagram of a leakage current protection system including a transformer 105 and a first switch group 104. The output end of the transformer 105 can be connected to the leakage current protection subsystem 10. The inverter 103 in different leakage current protection subsystems 10 forms a parallel connection relationship with the first switch group 104 and the transformer 105 in the leakage current protection system. The electrical connection between different leakage current protection subsystems 10 and the transformer 105 can be uniformly controlled, and the power supply switch of the photovoltaic power generation system can be uniformly controlled.

[0055] In a feasible implementation, the signal output by the leakage current sensor will reach the inverter 103, and the leakage current protection module 102 will be controlled by the inverter 103 to increase the impedance in the loop. Specifically, the switch control unit of the inverter 103 can be used to control the connection of the leakage current protection switch unit and the disconnection of the path switch unit, so as to increase the impedance in the loop, thereby reducing the leakage current in the leakage current loop, thereby protecting the human body from electric shock.

[0056] In a feasible implementation, when the number of leakage current protection subsystems 10 is one, the neutral point of the output end of the transformer 105 is grounded; when the number of leakage current protection subsystems 10 is greater than one, the neutral point of the output end of the transformer 105 is not grounded. If the leakage current protection system includes one leakage current protection subsystem 10, then the neutral line of the output end of the transformer 105 can be connected to the ground line. If there are more than one leakage current protection subsystems 10, the neutral point of the output end of the transformer 105 does not need to be grounded. Figure 7 The utility model is applicable to a leakage current protection system when a single inverter 103 is applied to a TN grounding system, and a leakage current protection system when two or more inverters 103 are connected in parallel to an IT grounding system, that is, the leakage current protection system may include one leakage current protection subsystem 10 and a TN grounding system, or the leakage current protection system may include more than one leakage current protection subsystem 10 and an IT grounding system.

[0057] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0058] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0060] Finally, it should be noted that the above embodiments are only specific implementation methods of the utility model, which are used to illustrate the technical solution of the utility model, rather than to limit it. The protection scope of the utility model is not limited thereto. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art should understand that any technician familiar with the technical field can still modify the technical solution recorded in the above embodiments within the technical scope disclosed by the utility model, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solution of the embodiment of the utility model, and should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model shall be based on the protection scope of the claims.

Claims

1. A leakage current protection system, characterized in that: include: At least one leakage current protection subsystem, each leakage current protection subsystem comprising a photovoltaic unit, a leakage current protection module and an inverter; Wherein, the leakage current protection module includes at least two leakage current protection submodules, the positive pole of the photovoltaic unit is electrically connected to the positive pole of the corresponding inverter through at least one leakage current protection submodule arranged on the DC positive pole, and the negative pole of the photovoltaic unit is electrically connected to the negative pole of the corresponding inverter through at least one leakage current protection submodule arranged on the DC negative pole; The photovoltaic unit is used to generate direct current; The inverter is used to convert the direct current into alternating current; The leakage current protection module is used to determine whether the leakage current on the DC positive electrode and the DC negative electrode has a sudden change, and to increase the impedance in the corresponding leakage current loop when the leakage current has a sudden change.

2. The leakage current protection system according to claim 1, characterized in that: Each leakage current protection submodule includes at least one leakage current protection unit and at least one leakage current judgment unit; One end of the leakage current protection unit is electrically connected to an output end of the corresponding photovoltaic unit, one end of the leakage current judgment unit is electrically connected to an input end of the corresponding inverter, and the other end of the leakage current protection unit is electrically connected to the other end of the leakage current judgment unit; The leakage current judgment unit is used to judge whether a leakage current in a corresponding leakage current loop has a sudden change; The leakage current protection unit is used to increase the impedance in the corresponding leakage current loop when a leakage current in the corresponding leakage current loop suddenly occurs.

3. The leakage current protection system according to claim 2, characterized in that: Each leakage current protection unit includes at least one path switch unit, at least one leakage current protection switch unit and at least one blocking device; One end of the path switch unit is electrically connected to an output end of the corresponding photovoltaic unit, and the other end of the path switch unit is electrically connected to one end of the corresponding leakage current judgment unit; One end of the leakage current protection switch unit is electrically connected to an output end of the corresponding photovoltaic unit, the other end of the leakage current protection switch unit is electrically connected to one end of the corresponding blocking device, and the other end of the corresponding blocking device is electrically connected to one end of the corresponding leakage current judgment unit; The blocking device is used to increase the impedance in the corresponding leakage current loop.

4. The leakage current protection system according to claim 3, characterized in that: The leakage current protection switch unit and the path switch unit are controllable switch units, and the leakage current protection switch unit and the path switch unit include a communication unit; The communication unit is used for communicating with the switch control unit.

5. The leakage current protection system according to claim 4, characterized in that: The controllable switch unit is a semiconductor device type or a mechanical type switch.

6. The leakage current protection system according to claim 3, characterized in that: The inverter comprises a switch control unit, and the switch control unit is used to control the closing and opening of the leakage current protection switch unit and the path switch unit in the leakage current protection unit.

7. The leakage current protection system according to claim 4, characterized in that: The blocking device includes at least one resistor.

8. The leakage current protection system according to claim 2, characterized in that: The leakage current judgment unit is a leakage current sensor.

9. The leakage current protection system according to any one of claims 1 to 8, characterized in that: Also includes: A transformer and a first switch group; The transformer is used to output the alternating current; The first switch group is used to close or open the electrical connection between the inverter and the transformer.

10. The leakage current protection system according to claim 9, characterized in that: When the number of the leakage current protection subsystem is one, the neutral point of the output end of the transformer is grounded; When the number of the leakage current protection subsystems is greater than one, the neutral point of the transformer output end is not grounded.

Images