Intelligent combiner box and protection method and related device thereof

Abstract

The invention discloses an intelligent combiner box, a protection method thereof and a related device, and relates to the technical field of power electronics. The intelligent combiner box is connected with each branch of the corresponding DC power supply, is connected in parallel with the DC switch, and is connected with the DC side of the inverter through the DC switch. Moreover, in the intelligent combiner box, the voltage sampling unit is used for sampling the confluence voltage after the branches are connected in parallel, and the branch current sampling of the branches is realized through the current sampling units; then, the control unit determines that an arc discharge or short circuit fault occurs on the direct current side of the inverter under the conditions that the confluence voltage shakes after the confluence voltage drops and the sum of the branch currents is greater than a preset current value, so that the identification of the arc discharge or short circuit fault is realized; and then the direct-current switch is controlled to trip, so that the arc discharge or short circuit fault is removed, and the fault is prevented from being expanded. In addition, interference of other normal working conditions such as normal switch-on of the switch can be eliminated, and misoperation is avoided.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to an intelligent combiner box, its protection method, and related devices. Background Technology

[0002] In real-world power plant environments, due to the high DC voltage, short circuits or other insulation failures frequently occur on the DC side of photovoltaic module cables or inverters. This can easily lead to severe arcing on the DC side of the inverter, causing fires and resulting in significant economic losses to the power plant. Current technologies cannot accurately detect arcing or short-circuit faults, thus failing to promptly isolate them and easily allowing the fault to escalate. Summary of the Invention

[0003] In view of the above problems, this application provides an intelligent combiner box, its protection method, and related devices to detect arcing or short-circuit faults on the DC side of the inverter and prevent the fault from escalating. The specific solution is as follows:

[0004] The first aspect of this application provides an intelligent combiner box, comprising: a DC switch, multiple branches, a control unit, a voltage sampling unit, and multiple current sampling units; wherein...

[0005] One side of each branch is used to connect to the corresponding DC power supply;

[0006] The other side of each of the branches is connected in parallel to the first side of the DC switch;

[0007] The second side of the DC switch is used to connect to the DC side of the inverter;

[0008] The voltage sampling unit is used to sample the bus voltage after all the branches are connected in parallel;

[0009] Each of the aforementioned current sampling units is used to sample the branch current of each of the aforementioned branches;

[0010] The control unit is connected to the output terminal of the voltage sampling unit, the output terminal of each current sampling unit, and the control terminal of the DC switch. The control unit is used to determine that an arcing or short circuit fault has occurred on the DC side of the inverter when the bus voltage drops and jitters and the sum of the currents of each branch is greater than a preset current value, and to control the DC switch to trip.

[0011] In one possible implementation, the control unit is further configured to determine, when the bus voltage drops and becomes greater than the DC-side startup voltage of the inverter, that the system containing the smart combiner box is in normal operating condition with the switch closed.

[0012] In one possible implementation, the control unit is further configured to determine that an arcing or short-circuit fault has occurred on the DC side of the inverter when the bus voltage drops to less than the short-circuit voltage value and the sum of the currents of each branch is greater than the preset current value, and to control the DC switch to trip.

[0013] In one possible implementation, the voltage sampling unit is located on the first or second side of the DC switch.

[0014] In one possible implementation, the intelligent combiner box further includes a switching power supply; the switching power supply is used to power the control unit.

[0015] In one possible implementation, the input terminal of the switching power supply is connected to the second side of the DC switch;

[0016] The output terminal of the switching power supply is connected to the power supply terminal of the control unit.

[0017] In one possible implementation, the switching power supply includes: a buck circuit;

[0018] The high-voltage side of the step-down circuit serves as the input terminal of the switching power supply.

[0019] The low-voltage side of the step-down circuit serves as the output terminal of the switching power supply.

[0020] In one possible implementation, the switching power supply further includes: at least one energy storage capacitor;

[0021] The energy storage capacitor is connected between the positive and negative terminals of the output of the switching power supply.

[0022] A second aspect of this application provides a protection method for an intelligent combiner box, comprising:

[0023] Determine whether the bus voltage of the intelligent combiner box has dropped;

[0024] If the bus voltage drops, it is determined whether the bus voltage meets the preset jitter condition within a preset time after the drop and whether the sum of the currents of each branch in the smart combiner box is greater than the preset current value.

[0025] If the bus voltage meets the preset jitter condition within the preset time and the sum of the currents of each branch is greater than the preset current value, it is determined that an arcing or short-circuit fault has occurred on the DC side of the inverter connected to the smart combiner box, and the DC switch of the smart combiner box is tripped; and the process returns to the step of determining whether the bus voltage of the smart combiner box has dropped.

[0026] In one possible implementation, the preset jitter condition is: a first condition, or a second condition;

[0027] The first condition is that the rate of change of the average voltage of the bus voltage in each time period within the preset time is unstable;

[0028] The second condition is that the discrete values ​​of the bus voltage fluctuate within the preset time period.

[0029] In one possible implementation, the first condition is either a descent condition or a slope condition.

[0030] The falling segment condition is: the average voltage of the bus voltage in the later time period within the preset time is less than the sum of the average voltage of the previous time period and the preset margin.

[0031] The slope condition is: the slope of the change of the average voltage of the bus voltage in each time period within the preset time includes both positive and negative values.

[0032] In one possible implementation, the second condition is: each of the discrete values ​​fluctuates around a preset constant value, or each of the discrete values ​​increases at least once and decreases at least once in chronological order.

[0033] In one possible implementation, if the bus voltage drops, it further includes:

[0034] Determine whether the average voltage of the bus voltage in each time period within the preset time is greater than the DC-side startup voltage of the inverter;

[0035] If the average value of each voltage is greater than the DC-side start-up voltage, it is determined that the system where the intelligent combiner box is located has entered a normal operating condition of switch closing; and the process returns to the step of determining whether the combiner voltage of the intelligent combiner box has dropped.

[0036] In one possible implementation, if the bus voltage drops, then:

[0037] First, determine whether the average value of each voltage within the preset time period is greater than the DC-side startup voltage;

[0038] Then determine whether the bus voltage meets the preset jitter condition within the preset time and whether the sum of the currents of each branch is greater than the preset current value.

[0039] In one possible implementation, determining whether the bus voltage meets a preset jitter condition and whether the sum of the currents in each branch of the smart combiner box is greater than a preset current value within a preset time period after the voltage drop includes: first determining whether the bus voltage meets the falling segment condition within the preset time period and whether the sum of the currents in each branch is greater than the preset current value; then, if the bus voltage does not meet the falling segment condition within the preset time period, determining whether the average voltage value of the bus voltage in the last time period within the preset time period is less than the short-circuit voltage value and whether the sum of the currents in each branch is greater than the preset current value.

[0040] If the bus voltage meets the falling segment condition within the preset time period, or the average voltage of the bus voltage in the last time period within the preset time period is less than the short-circuit voltage value, and the sum of the currents of each branch is greater than the preset current value, then it is determined that an arcing or short-circuit fault has occurred on the DC side of the inverter, and the DC switch is controlled to trip; and the process returns to the step of determining whether the bus voltage of the intelligent combiner box has dropped.

[0041] In one possible implementation, determining whether the bus voltage meets a preset jitter condition within a preset time after a voltage drop and whether the sum of the currents in each branch of the smart combiner box is greater than a preset current value includes:

[0042] Determine whether the bus voltage satisfies the slope condition or the second condition within the preset time period, and whether the sum of the currents of each branch is greater than the preset current value; and determine whether the average voltage of the bus voltage in at least the last time period within the preset time period is less than the short-circuit voltage value, and whether the sum of the currents of each branch is greater than the preset current value.

[0043] If the bus voltage meets the slope condition or the second condition within the preset time period, or if the average voltage of the bus voltage in the last time period within the preset time period is less than the short-circuit voltage value, and the sum of the currents of each branch is greater than the preset current value, then it is determined that an arcing or short-circuit fault has occurred on the DC side of the inverter, and the DC switch is controlled to trip; and the process returns to the step of determining whether the bus voltage of the intelligent combiner box has dropped.

[0044] In one possible implementation, determining whether the bus voltage of the smart combiner box has dropped includes:

[0045] Determine whether the bus voltage is less than a preset dropout limit;

[0046] If the bus voltage is less than the preset drop lower limit, then determine whether the bus voltage will continue to drop by a preset difference within a subsequent preset time period;

[0047] If the bus voltage continues to drop by a preset difference value within a subsequent preset time period, it is determined that the bus voltage of the smart combiner box has dropped.

[0048] A third aspect of this application provides a control device including a processor and a memory, the memory being used to store programs, instructions, or code, and the processor being used to execute the programs, instructions, or code in the memory to perform the protection method for the smart combiner box as described in the second aspect or any implementation thereof.

[0049] The fourth aspect of this application provides a computer-readable storage medium storing a computer program that is loaded by a processor to execute the protection method for a smart combiner box as described in the second aspect or any implementation thereof.

[0050] A fifth aspect of this application provides a power generation system, comprising: an inverter and at least one intelligent combiner box as described in the first aspect or any implementation thereof; wherein...

[0051] The branch side of the intelligent combiner box is used to connect at least one DC power source;

[0052] The combiner side of the intelligent combiner box is used to connect to the DC side of the inverter;

[0053] The AC side of the inverter is used to connect to the power grid and / or load;

[0054] The inverter is communicatively connected to the smart combiner box.

[0055] Using the above technical solution, the intelligent combiner box provided in this application connects each branch of the corresponding DC power supply in parallel to a DC switch, and then connects to the DC side of the inverter through the DC switch. Moreover, the intelligent combiner box also samples the combiner voltage after the parallel connection of each branch through a voltage sampling unit, and samples the branch current of each branch through each current sampling unit. Then, when the combiner voltage drops and fluctuates and the sum of the currents of each branch is greater than a preset current value, the control unit determines that an arcing or short-circuit fault has occurred on the DC side of the inverter, thereby realizing the identification of the arcing or short-circuit fault. Then, by controlling the DC switch to trip, the arcing or short-circuit fault is cleared, preventing the fault from escalating. Attached Figure Description

[0056] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0057] Figure 1A schematic diagram of a smart combiner box provided in an embodiment of this application;

[0058] Figure 2 A schematic diagram of a power generation system provided in an embodiment of this application;

[0059] Figure 3 Another structural schematic diagram of the intelligent combiner box provided in the embodiments of this application;

[0060] Figure 4 A flowchart illustrating a protection method for an intelligent combiner box provided in an embodiment of this application;

[0061] Figure 5 Another flowchart illustrating the protection method for the intelligent combiner box provided in this application embodiment;

[0062] Figure 6 Another flowchart illustrating the protection method for the intelligent combiner box provided in this application embodiment;

[0063] Figure 7 Another flowchart illustrating the protection method for the intelligent combiner box provided in this application embodiment;

[0064] Figure 8 This is a schematic diagram of a control device provided in an embodiment of this application. Detailed Implementation

[0065] The embodiments of this application are described below with reference to the accompanying drawings. The terminology used in the implementation section of this application is for explaining specific embodiments only and is not intended to limit the scope of this application.

[0066] The embodiments of this application are described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Those skilled in the art will understand that with the development of technology and the emergence of new scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

[0067] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms are interchangeable where appropriate; this is merely a way of distinguishing objects with the same attributes in the embodiments of this application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, so that a process, method, system, product, or apparatus that comprises a series of elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to those processes, methods, products, or apparatuses.

[0068] This application provides an intelligent combiner box to detect arcing or short-circuit faults on the DC side of the inverter, preventing the fault from escalating. The specific solution is as follows:

[0069] like Figure 1 As shown, the intelligent combiner box includes: a DC switch K, multiple (n are shown as an example in the figure) branches, a control unit 101, a voltage sampling unit 102, and multiple current sampling units 103; wherein:

[0070] One side of each branch is used to connect to the corresponding DC power supply. Specifically, the DC power supply can refer to photovoltaic units such as photovoltaic strings, or energy storage units such as battery clusters; Figure 1 The example of a photovoltaic unit is shown in the text. Figure 1 As shown, the positive terminal of the first branch is connected to the positive terminal PV1+ of the first photovoltaic unit PV1, and the negative terminal of the first branch is connected to the negative terminal PV1- of the first photovoltaic unit PV1; ...; the positive terminal of the nth branch is connected to the positive terminal PVn+ of the nth photovoltaic unit PVn, and the negative terminal of the first branch is connected to the negative terminal PVn- of the nth photovoltaic unit PVn. The value of n is not limited, as long as it is an integer greater than 1, and is within the scope of protection of this application. In practical applications, each branch's positive and negative terminal paths can be equipped with corresponding fuses, such as... Figure 1 The fuse shown.

[0071] The other side of each branch is connected in parallel to the first side of the DC switch K, and the second side of the DC switch K is used to connect to the DC side of the inverter; see details below. Figure 1 The positive terminals PV1+ to PVn+ of each photovoltaic unit are connected in parallel, and the connection point is connected to the DC positive terminal DC+ of the inverter through the positive switch in the DC switch K; the negative terminals PV1- to PVn- of each photovoltaic unit are connected in parallel, and the connection point is connected to the DC negative terminal DC- of the inverter through the negative switch in the DC switch K.

[0072] The voltage sampling unit 102 is used to sample the bus voltage after the branches are connected in parallel. In practical applications, the voltage sampling unit 102 can be set on the first side of the DC switch K or the second side of the DC switch K, depending on the specific application environment, and is not limited here. The specific implementation form of the voltage sampling unit 102 is not limited, and any implementation form in the prior art can be used, as long as it can achieve the sampling of the bus voltage.

[0073] Each current sampling unit 103 is used to sample the branch current of each branch. For example... Figure 1 As shown, each branch has a corresponding current sampling unit 103 installed in its positive path to sample the current of that branch. In practical applications, the current sampling unit 103 can also be installed in the negative path of the corresponding branch. Additionally, current sampling units 103 can be installed in the positive or negative paths of n-1 branches to sample the current of those n-1 branches. Furthermore, another current sampling unit 103 can be installed in the positive or negative path of the first side of the DC switch K to sample the current of the parallel connection of the branches, and then calculate the current of the last branch. The location of each current sampling unit 103 can be determined according to the actual application environment and is not limited here. The specific implementation of the current sampling unit 103 is not limited; any implementation in the prior art can be used, as long as it can achieve current sampling at the corresponding location.

[0074] In addition, the control unit 101 is connected to the output terminal of the voltage sampling unit 102 to receive the sampling information of the bus voltage from the voltage sampling unit 102, enabling the intelligent combiner box to realize the bus voltage detection function. The control unit 101 is also connected to the output terminal of each current sampling unit 103 to receive the sampling information of each branch current, enabling the intelligent combiner box to realize the branch current detection function. The control unit 101 is also connected to the control terminal of the DC switch K to realize the on / off control of the DC switch K, such as controlling the DC switch K to be engaged, disengaged, or tripped.

[0075] Furthermore, the control unit 101 is also used to: determine that an arcing or short-circuit fault has occurred on the DC side of the inverter when the bus voltage drops and then fluctuates and the sum of the currents of each branch is greater than a preset current value, and control the DC switch K to trip.

[0076] like Figure 2As shown, the DC side of inverter 20 can be connected to the combiner sides of multiple smart combiner boxes 10 via a DC bus, and inverter 20 is communicatively connected to each smart combiner box 10. At this time, an arcing or short-circuit fault occurs on the DC side of inverter 20, specifically including at least one of the following situations: an arcing or short-circuit fault occurs on the DC side of the DC / AC conversion circuit in inverter 20; an arcing or short-circuit fault occurs in the line between the DC side of inverter 20 and each connected smart combiner box 10; an arcing or short-circuit fault occurs in each corresponding smart combiner box 10; and an arcing or short-circuit fault occurs between each corresponding smart combiner box 10 and its connected DC power supply (…). Figure 2 (The example of a photovoltaic unit in China) shows that the lines between them experienced arcing or short-circuit faults.

[0077] In the event of an arcing or short-circuit fault on the DC side of inverter 20, the bus voltage on the DC side of inverter 20, i.e., the voltage of the DC bus, will decrease. Figure 1 and Figure 2 The voltage between DC+ and DC- shown in the diagram will first drop and then fluctuate, and the output current of each DC power supply will be relatively large. Since the bus voltage is equal to the bus voltage of each intelligent combiner box 10 connected to the inverter 20, and the output current of the DC power supply is also the forward current of each branch in the corresponding intelligent combiner box 10, it can be concluded that: in the event of an arcing or short-circuit fault on the DC side of the inverter 20, the bus voltage of each intelligent combiner box 10 connected to the DC side of the inverter 20 will drop and then fluctuate, and the sum of the currents in each branch will be relatively large, for example, greater than a preset current value. That is, the arcing or short-circuit fault can be detected through the bus voltage detection function and branch current detection function of the intelligent combiner box 10; and the DC switch K can be tripped in a timely manner to clear the arcing or short-circuit fault, preventing the fault from escalating and affecting the system.

[0078] The intelligent combiner box 10 provided in this embodiment has a control unit 101 that can detect arcing or short-circuit faults on the DC side of the inverter 20 in a timely manner through the above principle. After identifying the arcing or short-circuit fault, it can control the DC switch K to trip in a timely manner to cut off the arcing or short-circuit fault and prevent the fault from escalating.

[0079] In addition, the simple short-circuit detection scheme commonly used in related technologies not only cannot accurately detect arcing or short-circuit faults and thus isolate the fault, but also has the risk of false tripping. For example, when the DC side of inverter 20 is performing a normal switch closing operation, it may be mistakenly judged as an arcing or short-circuit fault due to the instantaneous drop in bus voltage, thus causing the arcing protection to malfunction.

[0080] Therefore, this embodiment provides another type of intelligent combiner box 10. Based on the previous embodiment, its control unit 101 is also used to determine the normal operating condition of the system where the intelligent combiner box 10 is located when the combiner voltage drops and is greater than the DC side start-up voltage of the inverter 20.

[0081] The normal operating conditions for the switch closing in the system where the aforementioned intelligent combiner box 10 is located include: the normal closing of the DC side switch of the DC / AC conversion circuit in the inverter 20, and the normal closing of the switch when the inverter 20 itself acts as an SVG (Static Var Generator). This is not limited here. Any switch that is likely to cause the above-mentioned malfunction when closing is within the scope of protection of this application.

[0082] When the system is in the normal operating condition of switch closing, the bus voltage on the DC side of inverter 20 will also drop. However, after the drop, the bus voltage will not fluctuate, but will be at a level greater than the DC side startup voltage of inverter 20. Therefore, when the control unit 101 detects through the bus voltage detection function that although the bus voltage drops, it is still greater than the DC side startup voltage after the drop, it can be determined that there is no arcing or short circuit fault at this time, but the normal operating condition of switch closing mentioned above has occurred. Therefore, it is not necessary to trip the DC switch K.

[0083] The intelligent combiner box 10 provided in this embodiment can eliminate interference from other normal operating conditions, such as normal switch closing, when a short circuit or other fault occurs on the DC side, causing arcing on the DC side. This avoids malfunctions.

[0084] Furthermore, the control unit 101 of the intelligent combiner box 10 can also be used to determine that an arcing or short-circuit fault has occurred on the DC side of the inverter 20 when the combiner voltage drops to less than the short-circuit voltage value and the sum of the currents of each branch is greater than the preset current value, and control the DC switch K to trip.

[0085] In the event of an arcing or short-circuit fault, the bus voltage will drop to a level lower than the short-circuit voltage value after the voltage drops, and the sum of the currents in each branch will also be greater than the preset current value. Therefore, it can be used to determine whether an arcing or short-circuit fault has occurred on the DC side of the inverter 20.

[0086] In practical applications, the control unit 101 can first determine whether the circuit is experiencing post-drop jitter or normal closing conditions. If neither of these conditions is met, it can then determine the short-circuit voltage value. This involves checking whether the bus voltage, after a drop, is below the short-circuit voltage value and the sum of the currents in each branch is greater than a preset current value. If so, it can be determined that an arcing or short-circuit fault has occurred on the DC side of the inverter 20, and the corresponding protection action can be executed, i.e., the DC switch K can be tripped. In this case, the short-circuit voltage value determination can be used as a supplementary determination to the post-drop jitter determination. That is, if the arcing or short-circuit fault cannot be identified through the post-drop jitter determination method, the arcing or short-circuit fault can be identified a second time through the short-circuit voltage value determination method, thereby increasing the probability of identifying the arcing or short-circuit fault.

[0087] That is, when a short circuit or other fault occurs on the DC side, causing arcing on the DC side, the control unit 101 of the intelligent combiner box 10 provided in this embodiment will, based on the voltage and current characteristics at the time of arcing or short circuit fault, eliminate interference from other operating conditions such as normal closing of the DC side switch of the inverter 20, accurately detect the arcing or short circuit fault on the photovoltaic unit side and the DC side of the inverter 20, and trip the DC switch K to prevent the fault from expanding and reduce losses.

[0088] In the above embodiments, the control unit 101 requires a certain power supply voltage to operate normally; its power supply voltage can be provided by an external power source, or by its own energy storage device such as a battery, or by its own power source. No limitation is made here, and all of these are within the protection scope of this application.

[0089] Based on the above embodiments, this embodiment provides a more detailed example of the structure of the intelligent combiner box 10, for example, see [link to relevant documentation]. Figure 3 The intelligent combiner box 10 may further include a switching power supply 104; the switching power supply 104 is used to power the control unit 101. In practical applications, the output terminal of the switching power supply 104 is connected to the power supply terminal of the control unit 101, and the switching power supply 104 can provide a suitable power supply voltage according to the needs of the control unit 101.

[0090] In addition, the power source of the switching power supply 104 is not limited. It can be an external power source, an energy storage device connected to the intelligent combiner box 10 such as a battery unit, or any side inside the intelligent combiner box 10; it depends on the specific application environment, and all of them are within the protection scope of this application.

[0091] In one example, the switching power supply 104 can draw power from the combiner side of the smart combiner box 10. When the DC side of the inverter 20 is connected to the combiner sides of multiple smart combiner boxes 10 via a DC bus, it is equivalent to the switching power supply 104 drawing power from the DC bus of the inverter 20. In practical applications, the input terminal of the switching power supply 104 is connected to the second side of the DC switch K, and this connection can be achieved inside or outside the smart combiner box 10; for example, the input terminal of the switching power supply 104 can be connected to the second side of the DC switch K inside the smart combiner box 10, but it is not limited to this. When drawing power from the combiner side of the smart combiner box 10, as long as there is a certain bus voltage on the DC side of the inverter 20, the input terminal of the switching power supply 104 can obtain the corresponding input power, thereby enabling power supply to the control unit 101. Correspondingly, the DC switch K controlled by the control unit 101 can specifically be a switch with a DC power supply trip function.

[0092] In practical applications, the switching power supply 104 can be implemented in various ways. For example, the switching power supply 104 may include a buck circuit; the high-voltage side of the buck circuit serves as the input terminal of the switching power supply 104; and the low-voltage side of the buck circuit serves as the output terminal of the switching power supply 104. In this case, the buck circuit can be used to reduce the input voltage of the switching power supply 104, thereby obtaining a suitable supply voltage to meet the power supply requirements of the control unit 101. When the switching power supply 104 is powered by the DC bus, the input voltage of the switching power supply 104 is also the bus voltage on the DC side of the inverter 20.

[0093] In another example, the switching power supply 104 may also include: at least one energy storage capacitor; such as Figure 3 As shown, the energy storage capacitor is connected between the positive and negative terminals of the output of the switching power supply 104, which can store the output energy of the buck circuit and filter and stabilize the output voltage of the buck circuit.

[0094] That is, the switching power supply 104 in the intelligent combiner box 10 can draw power from the bus voltage, and through its own energy storage capacitor, it can also ensure that the control unit 101 can complete the detection and isolation of the corresponding fault when a fault occurs.

[0095] Another embodiment of this application also provides a protection method for a smart combiner box, such as... Figure 4 As shown, the protection method includes:

[0096] S101. Determine whether the bus voltage of the intelligent combiner box has dropped.

[0097] In practical applications, the specific process of S101 may include... Figure 5 As shown:

[0098] S111. Determine whether the bus voltage is less than the preset dropout limit.

[0099] The value of the preset drop limit is not limited and can be determined according to the specific application environment. Any value that can characterize the drop in the bus voltage is within the protection scope of this application.

[0100] If the bus voltage is less than the preset dropout limit, then execute S112.

[0101] S112. Determine whether the bus voltage will continue to drop by a preset difference within the subsequent preset time period.

[0102] If the bus voltage continues to drop by a preset difference within a subsequent preset time period, it indicates that the bus voltage has experienced a sudden drop within a certain period of time. The specific values ​​of the preset time period and the preset difference are not limited and can be determined based on the specific application environment. Values ​​indicating a sudden drop in bus voltage are all within the protection scope of this application. When it is determined that the bus voltage continues to drop by a preset difference within a subsequent preset time period, it can be concluded that the bus voltage of the intelligent combiner box has dropped.

[0103] If the bus voltage drops after S101, then S102 is executed.

[0104] S102. Determine whether the bus voltage meets the preset jitter condition within a preset time after the voltage drop and whether the sum of the currents of each branch in the intelligent combiner box is greater than the preset current value.

[0105] The preset jitter condition is a condition that characterizes the jitter of the bus voltage. For details, please refer to the examples below, which will not be repeated here.

[0106] If the bus voltage meets the preset jitter condition within a preset time and the sum of the currents in each branch is greater than the preset current value, then execute S103 and return to S101.

[0107] S103. If an arcing or short-circuit fault is detected on the DC side of the inverter connected to the intelligent combiner box, the DC switch of the intelligent combiner box will be tripped.

[0108] If the device exhibits jitter after a drop and the sum of the currents in each branch exceeds the preset current value, an arcing or short-circuit fault is determined, and the DC switch is controlled to trip to clear the fault. The specific principle can be found in the above embodiment, and will not be repeated here.

[0109] The protection method provided in this embodiment can detect arcing or short-circuit faults in a timely manner based on the above principle, and can promptly cut off the arcing or short-circuit faults to prevent the faults from escalating.

[0110] In practical applications, the preset jitter condition can be set in a variety of ways. For example, it can be a first condition based on the rate of change of the average voltage of the bus voltage in each time period, or it can be a second condition based on the discrete values ​​of the bus voltage.

[0111] Specifically, after the bus voltage drops, the average voltage of the bus voltage in each time period within the preset time can be calculated. If the rate of change of each average voltage is unstable, then the first condition can be determined to be met.

[0112] Furthermore, this first condition can have several optional specific settings, such as:

[0113] Under normal operating conditions such as closing, the bus voltage will gradually recover to a level greater than the aforementioned DC-side starting voltage after a drop, and will not drop again. Therefore, when the bus voltage shows a drop segment, it can be determined that it has fluctuated. That is, whether the bus voltage shows a drop segment can be used to determine whether the first condition is met. Specifically, a drop segment condition can be set: within a preset time period, the average voltage of the bus in the later time period is less than the sum of the average voltage of the previous time period and the preset margin. If the drop segment condition is met, it can be determined that the bus voltage has fluctuated. The value of the preset margin is not limited; the smaller the value, the more sensitive the judgment. That is, the sensitivity of the judgment of arcing or short-circuit faults can be adjusted by adjusting the value of the preset margin.

[0114] Alternatively, when the bus voltage fluctuates, the average voltage of the bus voltage in each time period within the preset time will sometimes increase and sometimes decrease. That is, the slope of the change of the average voltage will have both positive and negative values. Therefore, the slope of the change, including both positive and negative values, can be used as a slope condition. If the bus voltage meets the slope condition, it can be determined that the bus voltage has fluctuated.

[0115] The first condition is mainly based on the rate of change of the average value of each voltage, and is not limited to the falling segment condition and slope condition mentioned above. As long as the condition that the bus voltage can be determined to be fluctuating based on the rate of change is within the scope of protection of this application.

[0116] In addition, after the bus voltage drops, the change curve of the bus voltage within the preset time period can be discretized to obtain the corresponding discrete values. If the discrete values ​​fluctuate, it can be determined that the second condition is met.

[0117] Similarly, this second condition can also have several optional specific settings, such as:

[0118] A preset constant value can be set for each discrete value. When each discrete value fluctuates around this preset constant value, it can be determined that the bus voltage is fluctuating. That is, the second condition can specifically be that each discrete value fluctuates around the preset constant value. The value of this constant preset value is not limited and can be set according to the specific application scenario, as long as it is within the upper and lower amplitudes of the bus voltage fluctuation under arcing or short-circuit faults.

[0119] Alternatively, one can determine whether each discrete value has both increased and decreased in chronological order; that is, the second condition can also be that each discrete value has increased at least once and decreased at least once in chronological order.

[0120] The second condition is mainly based on the judgment of each discrete value, and is not limited to the two specific settings mentioned above. As long as the condition that the bus voltage jitter can be determined based on each discrete value is within the protection scope of this application.

[0121] The selection of the preset jitter condition can be determined according to the application environment and is not limited here; moreover, the above-mentioned various optional examples are all examples of the preset jitter condition and are not limited to them. As long as the jitter of the bus voltage can be identified, it is within the protection scope of this application.

[0122] Based on the above embodiments, this embodiment provides another protection method for intelligent combiner boxes, see [link to relevant documentation]. Figure 6 (in) Figure 4 (Taking S101 as an example), if the bus voltage drops after S101, the protection method also includes:

[0123] S201. Determine whether the average voltage of the bus voltage in each time period within the preset time is greater than the DC side start-up voltage of the inverter.

[0124] If the average value of each voltage is greater than the DC side startup voltage, then execute S202 and return to S101.

[0125] S202. Determine that the system where the intelligent combiner box is located has a normal operating condition of switch closing.

[0126] By using S201 and S202, interference from the normal operating condition of the switch closing can be eliminated, preventing malfunctions such as arcing or short circuit faults. The specific principle can be found in the above embodiments, and will not be repeated here.

[0127] Moreover, after S103 or S202, the fault identification and judgment is completed, and the process can return to S101 to wait for the next fault identification and judgment after another drop occurs.

[0128] In practical applications, after a drop in bus voltage, S102 and S201 can be executed separately based on the bus voltage within the same preset time period; this preset time period can be 1 second, but is not limited to this. Furthermore, this application does not limit the execution order of S102 and S201 within this preset time period. In one example, S201 can be executed first, followed by S102; however, it is not limited to this. S102 can be executed first, followed by S201, or both can be executed simultaneously; it depends on the specific application environment, and all are within the scope of protection of this application.

[0129] Additionally, when the preset jitter condition is the aforementioned falling segment condition, see [link to relevant documentation]. Figure 7 Specifically, S102 may include: first executing S121, and then executing S122 if the bus voltage does not meet the falling segment condition within a preset time; specifically:

[0130] S121. Determine whether the bus voltage meets the falling segment condition within a preset time, and whether the sum of the currents in each branch is greater than the preset current value.

[0131] S122. Determine whether the average voltage of the bus voltage in the last time period within the preset time is less than the short-circuit voltage value, and whether the sum of the currents of each branch is greater than the preset current value.

[0132] After S121, if the bus voltage meets the falling segment condition within a preset time and the sum of the currents in each branch is greater than the preset current value, then S103 is executed and the process returns to S101. After S122, if the average voltage of the bus voltage in the last time period within the preset time is less than the short-circuit voltage value and the sum of the currents in each branch is greater than the preset current value, then S103 is executed again and the process returns to S101.

[0133] Figure 7 The document also demonstrates the three stages of this protection method, specifically:

[0134] The first stage is the process of judging bus voltage drop, which mainly includes S101. If the current bus voltage (i.e., the bus voltage) is less than the preset drop lower limit value U1, then the drop judgment is initiated. Then, it is determined whether a sudden drop in bus voltage occurs within a certain period of time, i.e., S112 is executed; if it occurs, the condition for bus voltage drop is met, and the process proceeds to the next stage; otherwise, the judgment is terminated directly.

[0135] The second stage mainly includes S201 and S121; in this stage, a sliding window for the average voltage is first created, including two consecutive time periods within the preset time period described in the above embodiment, and the average voltage of the bus voltage in the corresponding two time periods is calculated respectively. The average voltage of the previous time period is denoted as U. t1 The average voltage U over the next time period t2Then determine U t2 t1 Whether +A holds true is determined by calculating the slope of the bus voltage change over a period of time to judge whether the bus voltage fluctuates during arcing or short-circuit faults; where A is the aforementioned preset margin, and adjusting the value of this preset margin A can adjust the sensitivity of judging fluctuating changes; if U t2 t1 If +A is established, and the sum of the forward currents of all branches is greater than the preset current value, it can be considered a short circuit, arcing, or short circuit fault. Tripping control will then be initiated, and the current judgment will be exited. If the average voltage U over two time periods... t1 and U t2 If all values ​​are greater than the DC-side startup voltage of the inverter, then this operating condition is considered to be the DC switch closing process of the inverter, and the judgment is terminated.

[0136] If no fault is detected and the preset time has not yet ended, the judgment in the second stage continues as the sliding window moves; if no fault is detected until the preset time ends, the next stage is entered.

[0137] The third stage mainly includes S122; in this stage, the average voltage U of the next time period within the current sliding window is determined. t2 Check if the voltage is less than the short-circuit voltage value, and whether the sum of the forward currents of each branch is greater than the set value. If both are true, it can be assumed that an arcing or short-circuit fault has occurred on the DC side of the inverter, triggering trip control and exiting the current judgment; if neither is true, the current judgment is exited.

[0138] In another example, when the preset jitter condition is another condition, such as the slope condition or the second condition mentioned above, S102 may specifically include: S1201 and S1202; specifically:

[0139] S1201. Determine whether the bus voltage meets the slope condition or the second condition within a preset time, and whether the sum of the currents in each branch is greater than the preset current value.

[0140] S1202. Determine whether the average voltage of the bus voltage in at least the last time period within the preset time is less than the short-circuit voltage value, and whether the sum of the currents of each branch is greater than the preset current value.

[0141] If the bus voltage meets the slope condition or the second condition within a preset time period, and the sum of the currents in each branch is greater than the preset current value, then S103 can be executed and then S101 can be returned; if the average voltage of the bus voltage is less than the short-circuit voltage value for at least the last time period within the preset time period, and the sum of the currents in each branch is greater than the preset current value, then S103 can also be executed and then S101 can be returned.

[0142] and​​ Figure 7 The difference lies in the fact that, in the second stage, a slope condition can be used for jitter detection, or the bus voltage variation curve can be discretized, and jitter detection can be achieved by counting the fluctuations of the bus voltage around a preset constant value. Furthermore, S1201 will continue to run as the sliding window moves within the preset time period, while S1202 can either only run at the end of the preset time period or continue to run as the sliding window moves within the preset time period; this is not limited here. Other principles are the same as... Figure 7 The same applies, so I won't repeat myself.

[0143] The protection method provided in this embodiment establishes a hierarchical judgment mechanism. First, it determines whether a bus voltage drop has occurred. If a bus voltage drop is detected, it proceeds to the next level of judgment. Then, it determines whether arcing has occurred by judging the rate of change of the bus voltage and the sum of the forward currents of each branch. Based on the inverter's operating state, it establishes an exit mechanism for arcing or short-circuit fault judgment to prevent malfunction of the DC switch. This protection method can quickly and accurately identify and clear arcing or short-circuit faults occurring on the photovoltaic unit side and the inverter's DC side, preventing the fault from escalating and reducing losses.

[0144] In practical applications, the judgment thresholds in each stage and judgment step can be adjusted and set according to the actual situation, and no restrictions are imposed here.

[0145] In addition, this protection method can be executed by the control unit in the aforementioned smart combiner box, or by other control devices with corresponding functions, such as control devices connected to the smart combiner box; no limitation is made here, and all are within the scope of protection of this application.

[0146] Another embodiment of this application also provides a control device, such as... Figure 8 As shown, the control device may include a memory 301 and a processor 302. The processor 302 can be connected to the intelligent combiner box and can control the DC switch K in the intelligent combiner box. In practical applications, the processor 302 can be communicatively connected to the control unit in the intelligent combiner box, or it can be connected to the output terminal of the voltage sampling unit, the output terminal of the current sampling unit, and the control terminal of the DC switch in the intelligent combiner box, respectively; it depends on the specific application environment, and all of them are within the protection scope of this application.

[0147] The memory 301 can specifically be RAM (random access memory), flash memory, ROM (read only memory), EPROM (Electronic Programmable ROM, a type of non-volatile read-only memory), registers, hard disks, removable disks, etc.

[0148] The memory 301 is used to store computer instructions. When the computer instructions stored in the memory 301 are executed by the processor 302, the processor 302 can be used to execute the protection method of the smart combiner box described in any of the above embodiments. The memory 301 can also store data, such as various judgment thresholds involved in the above embodiments.

[0149] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this application is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, DSL (digital subscriber line)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available media can be magnetic media, such as floppy disks, hard disks, and magnetic tapes; or, the available media can be semiconductor media, such as SSDs (solid-state disks); the available media can also be other media, without limitation.

[0150] Another embodiment of this application provides a computer-readable storage medium storing a computer program that is loaded by a processor to execute the protection method for the smart combiner box as described in any of the above embodiments.

[0151] That is, the computer-readable storage medium is used to store the methods or algorithms provided in the above embodiments. Specifically, it can be RAM, flash memory, ROM, EPROM, registers, hard disk, removable disk, or any other form of storage medium in the art.

[0152] Another embodiment of this application also provides a power generation system, such as Figure 2 As shown, it includes: an inverter 20 and at least one smart combiner box 10; wherein,

[0153] The branch side of the intelligent combiner box 10 is used to connect at least one DC power source; the DC power source can refer to a photovoltaic unit such as a photovoltaic string, or an energy storage unit such as a battery cluster, and there is no limitation here.

[0154] The combiner side of the intelligent combiner box 10 is used to connect to the DC side of the inverter 20; the inverter 20 includes a DC / AC conversion circuit, and the DC side of the DC / AC conversion circuit is connected to the DC side of the inverter 20 through a corresponding DC side switch.

[0155] The AC side of the inverter 20 is used to connect to the power grid and / or load. In practical applications, inside the inverter 20, there can also be a corresponding AC side switch and filter circuit between its AC side and the AC side of the DC / AC conversion circuit. The AC side switch can also be set outside the inverter 20. The AC side of the inverter 20 can be connected to the grid connection point through a corresponding transformer to achieve connection to the power grid.

[0156] The inverter 20 is connected to the smart combiner box 10 via communication (as shown by the dotted line in the figure). The communication connection between the two can be wired or wireless, depending on the specific application environment, and both are within the protection scope of this application.

[0157] The structure and working principle of the intelligent combiner box 10 can be found in the above embodiments, and will not be repeated here.

[0158] In the field of photovoltaic power generation, combiner boxes in related technologies cannot protect against arcing or short-circuit faults occurring on the photovoltaic module side and the inverter DC side, causing huge economic losses to power plants. This embodiment, by adopting the intelligent combiner box 10 shown in any of the above embodiments, can accurately detect arcing or short-circuit faults based on the voltage and current characteristics during short circuits and arcing, while avoiding accidental tripping under various operating conditions such as inverter DC switch closing, and quickly clearing the fault by tripping the DC switch, thus preventing the fault from escalating and affecting the power plant.

[0159] Similar or identical parts between the various embodiments in this specification can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, for system or system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and relevant parts can be referred to the description of the method embodiments. The systems and system embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment solution according to actual needs. Those skilled in the art can understand and implement this without creative effort.

[0160] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0161] The features described above regarding the disclosed embodiments can be substituted for or combined with each other to enable those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A smart combiner box, characterized in that, include: DC switch, multiple branches, control unit, voltage sampling unit, and multiple current sampling units; among which, One side of each branch is used to connect to the corresponding DC power supply; The other side of each of the branches is connected in parallel to the first side of the DC switch; The second side of the DC switch is used to connect to the DC side of the inverter; The voltage sampling unit is used to sample the bus voltage after all the branches are connected in parallel; Each of the aforementioned current sampling units is used to sample the branch current of each of the aforementioned branches; The control unit is connected to the output terminal of the voltage sampling unit, the output terminal of each current sampling unit, and the control terminal of the DC switch. The control unit is used to determine that an arcing or short circuit fault has occurred on the DC side of the inverter when the bus voltage drops and jitters and the sum of the currents of each branch is greater than a preset current value, and to control the DC switch to trip.

2. The intelligent combiner box according to claim 1, characterized in that, The control unit is also used to determine that the system where the intelligent combiner box is located has a normal operating condition of switch closing when the combiner voltage drops and is greater than the DC side start-up voltage of the inverter.

3. The intelligent combiner box according to claim 1, characterized in that, The control unit is also used to determine that an arcing or short-circuit fault has occurred on the DC side of the inverter when the bus voltage drops to less than the short-circuit voltage value and the sum of the currents of each branch is greater than the preset current value, and to control the DC switch to trip.

4. The intelligent combiner box according to any one of claims 1 to 3, characterized in that, The voltage sampling unit is located on the first or second side of the DC switch.

5. The intelligent combiner box according to any one of claims 1 to 3, characterized in that, Also includes: A switching power supply; the switching power supply is used to power the control unit.

6. The intelligent combiner box according to claim 5, characterized in that, The input terminal of the switching power supply is connected to the second side of the DC switch; The output terminal of the switching power supply is connected to the power supply terminal of the control unit.

7. The intelligent combiner box according to claim 5, characterized in that, The switching power supply includes: a step-down circuit; The high-voltage side of the step-down circuit serves as the input terminal of the switching power supply. The low-voltage side of the step-down circuit serves as the output terminal of the switching power supply.

8. The intelligent combiner box according to claim 7, characterized in that, The switching power supply further includes: at least one energy storage capacitor; The energy storage capacitor is connected between the positive and negative terminals of the output of the switching power supply.

9. A protection method for an intelligent combiner box, characterized in that, include: Determine whether the bus voltage of the intelligent combiner box has dropped; If the bus voltage drops, it is determined whether the bus voltage meets the preset jitter condition within a preset time after the drop and whether the sum of the currents of each branch in the smart combiner box is greater than the preset current value. If the bus voltage meets the preset jitter condition within the preset time and the sum of the currents of each branch is greater than the preset current value, then it is determined that an arcing or short circuit fault has occurred on the DC side of the inverter connected to the intelligent combiner box, and the DC switch of the intelligent combiner box is controlled to trip. Then return to the step of determining whether the bus voltage of the intelligent combiner box has dropped.

10. The protection method for the intelligent combiner box according to claim 9, characterized in that, The preset jitter condition is either a first condition or a second condition; The first condition is that the rate of change of the average voltage of the bus voltage in each time period within the preset time is unstable; The second condition is that the discrete values ​​of the bus voltage fluctuate within the preset time period.

11. The protection method for the intelligent combiner box according to claim 10, characterized in that, The first condition is either a descent condition or a slope condition. The falling segment condition is: the average voltage of the bus voltage in the later time period within the preset time is less than the sum of the average voltage of the previous time period and the preset margin. The slope condition is: the slope of the change of the average voltage of the bus voltage in each time period within the preset time includes both positive and negative values.

12. The protection method for the intelligent combiner box according to claim 10, characterized in that, The second condition is that each of the discrete values ​​fluctuates around a preset constant value, or that each of the discrete values ​​increases at least once and decreases at least once in chronological order.

13. The protection method for the intelligent combiner box according to claim 9, characterized in that, If the bus voltage drops, it also includes: Determine whether the average voltage of the bus voltage in each time period within the preset time is greater than the DC-side startup voltage of the inverter; If the average value of each voltage is greater than the DC-side start-up voltage, it is determined that the system where the intelligent combiner box is located has entered a normal operating condition of switch closing; and the process returns to the step of determining whether the combiner voltage of the intelligent combiner box has dropped.

14. The protection method for the intelligent combiner box according to claim 13, characterized in that, If the bus voltage drops, then: First, determine whether the average value of each voltage within the preset time period is greater than the DC-side startup voltage; Then determine whether the bus voltage meets the preset jitter condition within the preset time and whether the sum of the currents of each branch is greater than the preset current value.

15. The protection method for the intelligent combiner box according to any one of claims 9 to 14, characterized in that, Determining whether the bus voltage meets a preset jitter condition within a preset time after a voltage drop and whether the sum of the currents in each branch of the smart combiner box is greater than a preset current value includes: first determining whether the bus voltage meets a falling segment condition within the preset time and whether the sum of the currents in each branch is greater than the preset current value; then, if the bus voltage does not meet the falling segment condition within the preset time, determining whether the average voltage value of the bus voltage in the last time period within the preset time is less than the short-circuit voltage value and whether the sum of the currents in each branch is greater than the preset current value. If the bus voltage meets the falling segment condition within the preset time period, or the average voltage of the bus voltage in the last time period within the preset time period is less than the short-circuit voltage value, and the sum of the currents of each branch is greater than the preset current value, then it is determined that an arcing or short-circuit fault has occurred on the DC side of the inverter, and the DC switch is controlled to trip; and the process returns to the step of determining whether the bus voltage of the intelligent combiner box has dropped.

16. The protection method for the intelligent combiner box according to any one of claims 9 to 14, characterized in that, Determining whether the bus voltage meets a preset jitter condition within a preset time after a voltage drop and whether the sum of the currents in each branch of the smart combiner box is greater than a preset current value includes: Determine whether the bus voltage satisfies the slope condition or the second condition within the preset time period, and whether the sum of the currents of each branch is greater than the preset current value; and determine whether the average voltage of the bus voltage in at least the last time period within the preset time period is less than the short-circuit voltage value, and whether the sum of the currents of each branch is greater than the preset current value. If the bus voltage meets the slope condition or the second condition within the preset time period, or if the average voltage of the bus voltage in at least the last time period within the preset time period is less than the short-circuit voltage value, and the sum of the currents of each branch is greater than the preset current value, then it is determined that an arcing or short-circuit fault has occurred on the DC side of the inverter, and the DC switch is controlled to trip; and the process returns to the step of determining whether the bus voltage of the intelligent combiner box has dropped.

17. The protection method for the intelligent combiner box according to any one of claims 9 to 14, characterized in that, Determining whether the bus voltage of the intelligent combiner box has dropped includes: Determine whether the bus voltage is less than a preset dropout limit; If the bus voltage is less than the preset drop lower limit, then determine whether the bus voltage will continue to drop by a preset difference within a subsequent preset time period; If the bus voltage continues to drop by a preset difference value within a subsequent preset time period, it is determined that the bus voltage of the smart combiner box has dropped.

18. A control device, characterized in that, It includes a processor and a memory, the memory being used to store programs, instructions, or code, and the processor being used to execute the programs, instructions, or code in the memory to perform the protection method for the smart combiner box as described in any one of claims 9 to 17.

19. A computer-readable storage medium, characterized in that, The device contains a computer program that is loaded by a processor to execute the protection method for the smart combiner box as described in any one of claims 9 to 17.

20. A power generation system, characterized in that, include: Inverter and at least one smart combiner box as described in any one of claims 1 to 8; wherein, The branch side of the intelligent combiner box is used to connect at least one DC power source; The combiner side of the intelligent combiner box is used to connect to the DC side of the inverter; The AC side of the inverter is used to connect to the power grid and / or load; The inverter is communicatively connected to the smart combiner box.

Images