A photovoltaic fast shutdown system

Abstract

The present application discloses a photovoltaic fast shutdown system, including a switch group S1, a switch group S2 and a control module; each switch device of the switch group S1 is respectively connected in parallel with a corresponding number of photovoltaic modules of the photovoltaic string; each switch device of the switch group S2 is respectively connected in series between adjacent photovoltaic modules of the photovoltaic string; the control module is respectively connected to the switch group S1 and the switch group S2 for control. Beneficial effects of the present application: when shutting down the photovoltaic string, the switch group S1 only needs to bear the voltage of a single photovoltaic module at least, which can reduce the voltage level requirements of each switch group of the switch group S1; at the same time, by short-circuiting the photovoltaic module through the switch group S1, it can be ensured that no current passes through the switch group S2 when it is disconnected, thereby ensuring that the voltage spike of the switch group S2 is lower when it is disconnected; compared with the traditional method, the present application can effectively save system costs while ensuring the shutdown safety of the photovoltaic string.

Description

Technical Field

[0001] The present application relates to the field of renewable energy power generation, and in particular to a photovoltaic rapid shutdown system. Background Art

[0002] The existing fast shutdown device connects the switch device in series between the photovoltaic modules, and reduces the voltage borne by each switch device by connecting multiple switch devices in series on the same string.

[0003] However, in the actual shutdown process, due to the inconsistency of the parameters of each switching device and the driving circuit parameters, the shutdown time of each switching device may be different, and some switching devices may be shut down first. At this time, the switching devices that are shut down first need to withstand higher voltages, which may damage the switching devices. Summary of the invention

[0004] One of the objectives of the present application is to provide a photovoltaic fast shutdown system that can solve at least one defect in the above-mentioned background technology.

[0005] In order to achieve at least one of the above-mentioned purposes, the technical solution adopted in the present application is: a photovoltaic fast shutdown system, including a switch group S1, a switch group S2 and a control module; each switch device of the switch group S1 is respectively connected in parallel with a corresponding number of photovoltaic components of the photovoltaic string; each switch device of the switch group S2 is respectively connected in series between adjacent photovoltaic components of the photovoltaic string; the control module is respectively controlled and connected with the switch group S1 and the switch group S2; when the photovoltaic string is in normal operation, the control module controls the switch group S2 to remain closed and controls the switch group S1 to remain open; when the photovoltaic string is shut down from normal operation, the control module is suitable for successively controlling the switch group S1 to close, controlling the switch group S2 to open, and controlling the switch group S1 to open again.

[0006] Preferably, when the photovoltaic string is switched from being shut down to being operated normally, the control module is adapted to sequentially control the switch group S1 to be closed, control the switch group S2 to be closed, and control the switch group S1 to be opened.

[0007] Preferably, when the photovoltaic string is switched between normal operation and shutdown, the control module is suitable for performing interval control on adjacent actions between the switch group S1 and the switch group S2.

[0008] Preferably, the photovoltaic fast shutdown system also includes a plurality of voltage-equalizing circuits; in the switch group S1 and the switch group S2, the voltage-equalizing circuit is connected in parallel with at least all the switch devices of the switch group S2; the voltage-equalizing circuit adopts one of a passive RC circuit, an MOV resistor circuit, and a parallel circuit of a passive RC circuit and an MOV resistor circuit.

[0009] Preferably, the control module includes a controller, an S1 group drive unit and an S2 group drive unit; the S1 group drive unit is drive-connected to each switch device of the switch group S1, and the S2 group drive unit is drive-connected to each switch device of the switch group S2; the controller is communicatively connected to the S1 group drive unit and the S2 group drive unit, respectively, and the controller is suitable for receiving a command signal for controlling the photovoltaic string and sending corresponding control signals to the S1 group drive unit and the S2 group drive unit, respectively, so that the S1 group drive unit and the S2 group drive unit drive and control each switch device of the switch group S1 and each switch device of the switch group S2, respectively.

[0010] Preferably, the controller includes a communication circuit, an S1 drive signal generating circuit, a first delay circuit, an S2 drive signal generating circuit and a second delay circuit; the controller performs the following control process according to the working instruction received by the communication circuit: the communication circuit is suitable for forwarding the received working instruction to the S1 drive signal generating circuit; the S1 drive signal generating circuit sends a control signal to the S1 group drive unit according to the working instruction to control the switch group S1 to close; the S1 drive signal generating circuit is also suitable for forwarding the received working instruction to the first delay circuit so that the first delay circuit The working instruction is forwarded to the S2 drive signal generating circuit after the interval set waiting time; the S2 drive signal generating circuit sends a control signal to the S2 group drive unit according to the working instruction to control the switch group S2 to perform corresponding actions; the S2 drive signal generating circuit is also suitable for sending an instruction completion signal to the second delay circuit, so that the second delay circuit forwards the instruction completion signal to the S1 drive signal generating circuit after the interval set waiting time; the S1 drive signal generating circuit sends a control signal to the S1 group drive unit according to the instruction completion signal to control the switch group S1 to disconnect.

[0011] Preferably, the S1 group drive unit and the S2 group drive unit both include a power amplifier circuit and an isolation circuit; the power amplifier circuit is suitable for receiving the control signal sent by the controller and amplifying the signal and then outputting it to the isolation circuit; the isolation circuit is suitable for isolating the amplified control signal to output a drive signal corresponding to the number of switching devices in the switch group to each switching device in the switch group.

[0012] Preferably, the photovoltaic components of the photovoltaic string are divided into multiple adjacent groups according to a set number; the number of switch devices in the switch group S1 is equal to the number of photovoltaic components in the photovoltaic string, so that each switch device of the switch group S1 is respectively connected in parallel to each photovoltaic component of the photovoltaic string; the number of switch devices in the switch group S2 is equal to the number of groups of photovoltaic components, so that each switch device of the switch group S2 is respectively connected in series between two adjacent groups of photovoltaic components in the photovoltaic string.

[0013] Preferably, the photovoltaic components of the photovoltaic string are divided into multiple adjacent groups according to a set number; the number of switch devices in the switch group S1 and the number of switch devices in the switch group S2 are equal to the number of groups of photovoltaic components; each switch device of the switch group S1 is simultaneously connected in parallel with a set number of photovoltaic components in each group of the photovoltaic string, and each switch device of the switch group S2 is respectively connected in series between two adjacent groups of photovoltaic components in the photovoltaic string.

[0014] Preferably, the photovoltaic rapid shutdown system is externally disposed on an inverter of the photovoltaic system; or, the photovoltaic rapid shutdown system is internally disposed on an inverter of the photovoltaic system.

[0015] Compared with the prior art, the beneficial effects of this application are:

[0016] When shutting down the photovoltaic string, the switch group S1 only needs to withstand the voltage of a single photovoltaic module at least, which can reduce the voltage level requirements of each switch group of the switch group S1; at the same time, by short-circuiting the photovoltaic module through the switch group S1, it can be ensured that no current passes through the switch group S2 when it is disconnected, thereby ensuring that the voltage spike of the switch group S2 is lower when it is disconnected; compared with the traditional method, the present application can effectively save system costs while ensuring the safety of shutting down the photovoltaic string. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural diagram of a specific example 1 of the arrangement of the switch group S1 and the switch group S2 in the present application.

[0018] Figure 2 This is a schematic diagram of the structure of the photovoltaic fast shutdown system of the present application installed in the inverter.

[0019] Figure 3 It is a structural diagram of a specific example 2 of the arrangement of the switch group S1 and the switch group S2 in the present application.

[0020] Figure 4 It is a structural diagram of specific example 3 of the arrangement of the switch group S1 and the switch group S2 in the present application.

[0021] Figure 5 For this application Figure 1The specific example 1 shown is a schematic diagram of the state when the switch group S1 is opened and the switch group S2 is closed.

[0022] Figure 6 For this application Figure 1 The specific example 1 shown is a schematic diagram of the state when the switch group S1 and the switch group S2 are closed at the same time.

[0023] Figure 7 For this application Figure 1 The specific example 1 shown is a schematic diagram of the state when the switch group S1 is closed and the switch group S2 is opened.

[0024] Figure 8 This is a schematic diagram of the shutdown timing of the control signal in this application.

[0025] Fig. 9 This is a schematic diagram of the state in which the switch components of the switch group S1 in the present application are inconsistently turned on.

[0026] Fig.10 It is a structural diagram of voltage balancing setting of switch group S2 in this application.

[0027] Fig.11 Schematic diagram of the circuit structure of the S1 group drive unit in this application.

[0028] Fig.12 Schematic diagram of the circuit structure of the controller in this application. DETAILED DESCRIPTION

[0029] Below, the present application is further described in conjunction with specific implementation methods. It should be noted that in the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms should not be understood as necessarily being directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0030] In the description of the present application, it should be noted that directional words, such as the terms "center", "lateral", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating directions and positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of narrating the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific scope of protection of the present application.

[0031] It should be noted that the terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0032] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be connected, detachably connected, or integrated; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0034] The terms "including" and "having" and any variations thereof in the specification and claims of the present application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0035] One of the preferred embodiments of the present application is as follows: Figures 1 to 7As shown, one of the preferred embodiments includes a switch group S1, a switch group S2 and a control module; each switch device of the switch group S1 is respectively connected in parallel with the photovoltaic components corresponding to the photovoltaic string; each switch device of the switch group S2 is respectively connected in series between the adjacent photovoltaic components of the photovoltaic string; and the control module is respectively controlled and connected with the switch group S1 and the switch group S2. When the photovoltaic string is in normal operation, the control module controls the switch group S2 to remain closed and controls the switch group S1 to remain open; at this time, each photovoltaic component is connected in series through the switch group S2 to form a complete photovoltaic string, and the output of the photovoltaic string can be connected to the input of the inverter for power transmission. When the photovoltaic string is shut down from normal operation, the control module can first control the switch group S1 to close, then control the switch group S2 to open, and finally control the switch group S1 to open.

[0036] It is understandable that the traditional photovoltaic string shutdown is generally only provided with one switch group, namely, the switch group S2 corresponding to the present embodiment; however, for different switch devices in the same switch group, due to inconsistent parameters of the switch devices themselves or the drive circuits, the switch devices in the same switch group may be inconsistent when closed or opened, causing some switch devices to withstand too high a voltage.

[0037] In this embodiment, when the photovoltaic string is shut down from normal operation, the photovoltaic components of the photovoltaic string can be short-circuited by closing the switch group S1 first, so that when the switch group S2 is disconnected, the switch group S2 can be guaranteed to be disconnected with zero current, so that the stress and loss borne by each switch device of the switch group S2 are reduced to a minimum. In addition, when the switch group S1 is closed, each switch device of the switch group S1 only needs to bear the voltage of a single photovoltaic component at least, so when selecting the switch devices of the switch group S1, a switch device with a lower voltage level can be selected. At the same time, when the switch devices of the switch group S2 are disconnected, since there is no current passing through the switch devices of the switch group S2, the voltage peak of each switch device of the switch group S2 when disconnected is lower. Compared with the traditional solution, the switch devices of the switch group S2 can also be selected when selecting the switch devices of the switch group S2. Therefore, compared with the traditional solution, this embodiment can not only ensure the safety of the photovoltaic string when shutting down, but also effectively reduce the cost of the system.

[0038] It should be known that the specific structure and working principle of each switch device of the switch group S1 and the switch group S2 are well-known technologies to those skilled in the art; the switch units that can be used as switch devices include relays, unidirectional IGBTs, bidirectional IGBTs, and MOS tubes, etc. For each switch device of the switch group, a separate switch unit can be used, or multiple switch units can be used in series and parallel, which can be selected according to the actual needs of those skilled in the art.

[0039] In this embodiment, there are two specific installation methods for the photovoltaic rapid shutdown system. The first method is: Figure 1 As shown, the photovoltaic fast shutdown system is external to the inverter of the photovoltaic system; that is, the photovoltaic system includes photovoltaic strings, inverters and photovoltaic fast shutdown systems, and the photovoltaic fast shutdown system is connected to the photovoltaic system as an independent device. Figure 2 As shown, the photovoltaic fast shutdown system is built into the inverter of the photovoltaic system; that is, the photovoltaic system includes photovoltaic strings and an inverter, and the inverter includes the photovoltaic fast shutdown system, a DC / DC circuit, and a DC / AC circuit.

[0040] It should be known that the above two installation methods of the photovoltaic rapid shutdown system can meet the requirements of this application, and technicians in this field can make their own choices according to actual needs; in order to facilitate the description of subsequent content, the subsequent content will take the above-mentioned first installation method of the photovoltaic rapid shutdown system as an example for detailed description.

[0041] In this embodiment, there are many specific arrangements of the switch devices of the switch group S1 and the switch group S2. For ease of understanding, three specific arrangements will be described in detail below.

[0042] Specific example 1: Figure 1 As shown, the photovoltaic string includes N photovoltaic components, and the switch group S1 and the switch group S2 each include N switch devices. The photovoltaic components of the photovoltaic string can be marked as PV#1, PV#2, ..., PV#N, respectively, then the switch devices of the switch group S1 can be marked as S11, S12, ..., S1N, and the switch devices of the switch group S2 can be marked as S21, S22, ..., S2N.

[0043] The specific arrangement is: the switch device S11 is connected in parallel with the photovoltaic module PV#1, the switch device S12 is connected in parallel with the photovoltaic module PV#2, until the switch device S1N is connected in parallel with the photovoltaic module PV#N. The switch device S21 is connected in series between the photovoltaic modules PV#1 and PV#2, the switch device S22 is connected in series between the photovoltaic modules PV#2 and PV#3, until the switch device S2N is connected in series between the photovoltaic module PV#N and the inverter.

[0044] Specific example 2: Figure 3As shown, the N photovoltaic modules included in the photovoltaic string are divided into multiple adjacent groups according to a set number k, k>1. The number of switch devices in the switch group S1 is equal to the number of photovoltaic modules in the photovoltaic string, which is N, and the number of switch devices in the switch group S2 is equal to the number of groups of photovoltaic modules, which is N / k, where N / k is an integer. The photovoltaic modules of the photovoltaic string can be marked as PV#1, PV#2, ..., PV#N, respectively, then the switch devices of the switch group S1 can be marked as S11, S12, ..., S1N, and the switch devices of the switch group S2 can be marked as S21, S22, ..., S2(N / k).

[0045] The specific value of k can be selected according to the actual needs of the technicians in this field. For ease of understanding, the following description of the arrangement will be described in detail using k as 2 as an example, then the photovoltaic components of the photovoltaic string will be divided into N / 2 groups; of course, the value of k can also be 3 or 4, etc. The specific arrangement is: the switch device S11 is connected in parallel with the photovoltaic component PV#1, the switch device S12 is connected in parallel with the photovoltaic component PV#2, until the switch device S1N is connected in parallel with the photovoltaic component PV#N. The switch device S21 is connected in series between the photovoltaic components PV#2 and PV#3, the switch device S22 is connected in series between the photovoltaic components PV#4 and PV#5, until the switch device S2 (N / 2) is connected in series between the photovoltaic component PV#N and the inverter.

[0046] Specific example three: Figure 4 As shown, the N photovoltaic modules included in the photovoltaic string are divided into multiple adjacent groups according to a set number k, k>1. The number of switch devices in the switch group S1 and the switch group S2 is equal to the number of photovoltaic module groups, which is N / k, and N / k is an integer. The photovoltaic modules of the photovoltaic string can be marked as PV#1, PV#2, ..., PV#N, respectively, then the switch devices of the switch group S1 can be marked as S11, S12, ..., S1 (N / k), and the switch devices of the switch group S2 can be marked as S21, S22, ..., S2 (N / k).

[0047] The specific value of k can be selected according to the actual needs of the technicians in this field. For ease of understanding, the following description of the arrangement will be described in detail using k as 2 as an example, and the photovoltaic components of the photovoltaic string will be divided into N / 2 groups. The specific arrangement is: the switch device S11 is connected in parallel with the photovoltaic components PV#1 and PV#2 connected in series, the switch device S12 is connected in parallel with the photovoltaic components PV#3 and PV#4 connected in series, until the switch device S1 (N / 2) is connected in parallel with the photovoltaic components PV#N-1 and PV#N connected in series at the same time. The switch device S21 is connected in series between the photovoltaic components PV#2 and PV#3, the switch device S22 is connected in series between the photovoltaic components PV#4 and PV#5, until the switch device S2 (N / 2) is connected in series between the photovoltaic component PV#N and the inverter.

[0048] It can be understood that, for the above-mentioned specific example 1 and specific example 2, when the switch group S1 is closed, each switch device of the switch group S1 only needs to withstand the voltage of a single photovoltaic module; for the above-mentioned specific example 3, when the switch group S1 is closed, each switch device of the switch group S1 needs to withstand the voltage of k photovoltaic modules. Therefore, the voltage level of each switch device of the switch group S1 in the specific example 3 should be higher than the voltage level of the switch devices of the switch group S1 in the specific example 1 and the specific example 2. At the same time, compared with the specific example 1, the number of switch devices of the switch group S2 in the above-mentioned specific example 2 can be reduced by k times, thereby effectively reducing the conduction loss of the entire photovoltaic fast shutdown system; compared with the specific example 1, the number of switch devices of the switch group S1 and the switch group S2 in the above-mentioned specific example 3 can be reduced by k times, which can further reduce the conduction loss of the entire photovoltaic fast shutdown system. Therefore, the specific arrangement of switch group S1 and switch group S2 can be selected according to the actual needs of technical personnel in this field. In order to facilitate the description of subsequent contents, switch group S1 and switch group S2 will be described in detail using the above-mentioned specific example 1 as an example.

[0049] For ease of understanding, the shutdown process of a photovoltaic string can be described in detail in conjunction with the above specific example. Figure 5 As shown, when the photovoltaic string is in normal operation, the control module can control the switch devices S21 to S2N of the switch group S2 to be in a closed state, and control the switch devices S11 to S1N of the switch group S1 to be in an open state. Figure 6 As shown, the control module first controls the switch devices S11 to S1N of the switch group S1 to close, and at this time, the switch devices S11 to S1N are only subjected to the voltage of the corresponding single photovoltaic module; then Figure 7As shown, the control module can control the switch devices S21 to S2N of the switch group S2 to be disconnected. Since the switch group S1 is closed, no current flows through the switch devices S21 to S2N during the disconnection process, so the peak voltage borne during the disconnection process is very low; finally, as shown in FIG. Figure 1 As shown, the control module can control the switch devices S11 to S1N of the switch group S1 to be disconnected.

[0050] In this embodiment, it can be known from the above content that when the switch devices of the switch group are closed or opened, the parameters of the switch devices themselves or the drive circuit are inconsistent, which may cause the switch devices of the same switch group to be inconsistent when they are closed or opened; therefore, in order to further ensure the working safety of the switch group, the control module can perform interval control on the adjacent actions between the switch group S1 and the switch group S2 during the process of shutting down the photovoltaic string from normal operation. That is, during the shutdown process of the photovoltaic string, the control module can set an interval waiting time T1 between controlling the switch group S1 to close and controlling the switch group S2 to open, and the control module can set an interval waiting time T2 between controlling the switch group S2 to open and controlling the switch group S1 to open.

[0051] Specifically, Figure 8 As shown, the control module controls the signal PWM S1 The switch group S1 is driven and controlled by the control module through the control signal PWM S2 The switch group S2 is driven and controlled. When the photovoltaic string is operating normally, the control signal PWM S1 The control signal PWM is low level to drive the switch group S1 to the off state. S2 is high level to drive the switch group S2 to be in a closed state. When the control module receives the shutdown signal at time t1, the control module can control the signal PWM S1 Pull the control signal PWM to a high level to close the switch devices of the switch group S1. At time t2 after the interval waiting time T1, it can be considered that all the switch devices of the switch group S1 have completed closing. At this time, the control module can S2 Pull the control signal PWM to a low level to disconnect the switch group S2. At time t3 after the interval waiting time T2, it can be considered that all the switch devices of the switch group S2 have been disconnected. At this time, the control module can S1 Pull to low level to disconnect the switch group S1.

[0052] It should be known that the value of the interval waiting time T1 can be reasonably selected based on factors such as the device type and quantity of each switch device in the switch group S1; the value of the interval waiting time T2 can be reasonably selected based on factors such as the device type and quantity of each switch device in the switch group S2.

[0053] To facilitate the description of subsequent contents, the switching consistency of the switch group S1 and the switch group S2 during the shutdown process of the photovoltaic string can be analyzed. For the convenience of description, the switch group S1 is taken as an example.

[0054] like Fig. 9 As shown, when the switch group S1 is closed, it is assumed that there is an inconsistent closing situation, specifically, the switch device S11 is closed before other switch devices. At this time, the photovoltaic module PV#1 is short-circuited, and there is almost no voltage difference between the two ends of the switch device S11, so the short-circuit current i1 of the photovoltaic module PV#1 and the output current i2 of other photovoltaic modules are in opposite directions. It can be seen from the output characteristics of the photovoltaic module that the short-circuit current i1>output current i2, then the current flowing through the switch device S11 at this time is (i1- i2). When the switch group S1 is disconnected, since the switch group S2 has been disconnected, each switch device of the switch group S1 only needs to withstand the short-circuit current and voltage of one photovoltaic module. Based on the above analysis, it can be seen that the switch group S1 can only withstand the voltage and current of one photovoltaic module at most when it is closed or disconnected, so the switching consistency requirements for the switch devices of the switch group S1 are relatively low.

[0055] When switch group S2 is disconnected, almost no current flows through it, and the photovoltaic module is short-circuited, making the output voltage of the photovoltaic module relatively low. Therefore, switch group S2 has relatively low requirements on the consistency of the drive circuit parameters. However, when switch group S2 is closed, if the delay of the control signal is too long, the switch device that is closed and turned on last in switch group S2 will need to withstand a higher overvoltage, which may damage the device in severe cases. Therefore, in order to improve the reliability of the system, the action sequence of switch groups S1 and S2 when the photovoltaic string is shut down and works normally again can be controlled in sequence.

[0056] Specifically, when the photovoltaic string is turned off, the control module controls the switch group S1 and the switch group S2 to be in the open state. When the photovoltaic string is turned off to work normally, the control module can control the switch group S1 to close, then control the switch group S2 to close, and finally control the switch group S1 to open. And in order to further ensure the working safety of the switch group, the control module can perform interval control on the adjacent actions between the switch group S1 and the switch group S2 during the process of the photovoltaic string turning off to work normally. That is, during the process of the photovoltaic string turning off to work normally, the control module sets an interval waiting time T3 between controlling the switch group S1 to close and controlling the switch group S2 to open, and the control module sets an interval waiting time T4 between controlling the switch group S2 to open and controlling the switch group S1 to open.

[0057] It should be known that when the photovoltaic string is shut down and working normally, the control signal PWM S1 and PWM S2 The timing of the action is to switch the control signal PWM from the normal operation to the shutdown of the photovoltaic string. S1 and PWM S2 The value of the interval waiting time T3 can be reasonably selected according to factors such as the device type and quantity of each switch device in the switch group S1; the value of the interval waiting time T4 can be reasonably selected according to factors such as the device type and quantity of each switch device in the switch group S2.

[0058] In this embodiment, in order to improve the reliability of the system, in addition to setting an interval waiting time between the actions of the switch group S1 and the switch group S2, the influence of the difference in the drive circuit parameters on the system stability can also be reduced by voltage balancing the switch devices. Fig.10 As shown, the photovoltaic fast shutdown system also includes multiple voltage balancing circuits; from the above content, it can be seen that the switch group S1 has relatively low requirements for the consistency of the switch when closing or opening, while the switch group S2 has relatively high requirements for the consistency of the switch when closing, so the voltage balancing circuit is at least connected in parallel with each switch device of the switch group S2. That is, the voltage balancing circuit is respectively connected in parallel to each switch device of the card closing group S2, or the voltage balancing circuit is respectively connected in parallel to all the switch devices of the switch group S1 and the switch group S2. Through the setting of the voltage balancing circuit, it can at least ensure that the voltages received by each switch device of the switch group S2 when closing or opening are basically consistent, thereby ensuring the stability of the drive circuit parameters.

[0059] It should be known that there are many specific structures of the voltage balancing circuit. Common voltage balancing circuits can use a passive RC circuit, an MOV resistor circuit, or a parallel circuit of a passive RC circuit and an MOV resistor circuit. The specific structure can be selected according to the actual needs of those skilled in the art. For ease of understanding, the switch device S21 of the switch group S2 will be used as an example for specific description.

[0060] Specifically, Fig.10 As shown, if the voltage balancing circuit adopts a passive RC circuit, the basic structure of the passive RC circuit includes two parallel branches, one of which includes a resistor R1 and a capacitor C connected in series, and the other includes a resistor R2; both branches are connected in parallel with the switch device S21. If the voltage balancing circuit adopts an MOV resistor circuit, the basic structure of the MOV resistor circuit includes an MOV resistor connected in parallel with the switch device S21.

[0061] In this embodiment, Figures 1 to 7 As shown, the control module includes a controller, an S1 group drive unit and an S2 group drive unit. The S1 group drive unit is connected to each switch device of the switch group S1 for driving, and the S2 group drive unit is connected to each switch device of the switch group S2 for driving. The controller is connected to the S1 group drive unit and the S2 group drive unit for communication, respectively. The controller can receive a command signal for controlling the photovoltaic string and send a corresponding control signal to the S1 group drive unit and the S2 group drive unit, respectively, so that the S1 group drive unit and the S2 group drive unit drive and control each switch device of the switch group S1 and each switch device of the switch group S2, respectively.

[0062] It should be known that, in order to reduce the aforementioned interval waiting time and ensure the voltage balancing effect of each switch device of the switch group S2, the drive signals of all switch devices of the switch group S1 need to be from the same source, and the drive signals of all switch devices of the switch group S2 also need to be from the same source; therefore, in this embodiment, the drive control of the switch group S1 and the switch group S2 are respectively driven and controlled simultaneously by the corresponding drive units. The structures of the drive units of the S1 group and the S2 group are basically the same, and there are many specific structures. For the convenience of understanding, one of the structures will be described in detail below.

[0063] Specifically, Fig.11 As shown, both the S1 group drive unit and the S2 group drive unit include a power amplifier circuit and an isolation circuit. The power amplifier circuit can receive the control signal sent by the controller and amplify the signal before outputting it to the isolation circuit; the isolation circuit can isolate the amplified control signal to output a drive signal corresponding to the number of switch devices in the switch group to each switch device in the switch group. For ease of understanding, the following will take the S1 group drive unit as an example to briefly describe its working process.

[0064] like Fig.11 As shown, when the power amplifier circuit receives the control signal PWM output by the controller S1 After that, the power amplifier circuit can control the PWM signal S1 Perform power amplification and convert the amplified control signal into PWM S1 Output to the isolation circuit. The isolation circuit can amplify the control signal PWM S1 Perform isolation processing and output the drive signal PWM corresponding to the number of switches N in the switch group S1 S11 To PWM S1N It should be noted that the specific structure and working principle of the power amplifier circuit and the isolation circuit are well-known technologies for those skilled in the art, so they will not be described in detail here; the common power amplifier circuit can be in the form of a driver chip, and the isolation circuit can be in the form of an optical coupler isolation.

[0065] In this embodiment, the controller can adopt control chips such as ARM and DSP, or can adopt the form of hardware architecture; the specific structure and working principle of control chips such as ARM and DSP are well-known technologies to technical personnel in this field, so they will not be elaborated in detail here; the following will specifically describe the form of hardware architecture adopted by the controller.

[0066] Specifically, Fig.12 As shown, the controller includes a communication circuit, an S1 drive signal generating circuit, a first delay circuit, an S2 drive signal generating circuit and a second delay circuit. The output end of the communication circuit is connected to the input end of the S1 drive signal generating circuit for communication, the output end of the S1 drive signal generating circuit is connected to the input end of the S1 group drive unit and the first extension circuit for communication, the output end of the first delay circuit is connected to the input end of the S2 drive signal generating circuit for communication, the output end of the S2 drive signal generating circuit is connected to the S2 drive unit and the input end of the second delay circuit for communication, and the output end of the second delay circuit is connected to the input end of the S1 drive signal generating circuit for communication.

[0067] The controller performs the following control process according to the work instruction received by the communication circuit: the communication circuit can forward the received work instruction to the S1 drive signal generation circuit. The S1 drive signal generation circuit sends a control signal to the S1 group drive unit according to the work instruction to control the switch group S1 to close. The S1 drive signal generation circuit can also forward the received work instruction to the first delay circuit, so that the first delay circuit forwards the work instruction to the S2 drive signal generation circuit after the waiting time set at the interval. The S2 drive signal generation circuit sends a control signal to the S2 group drive unit according to the work instruction to control the switch group S2 to perform a corresponding action. The S2 drive signal generation circuit can also send an instruction completion signal to the second delay circuit, so that the second delay circuit forwards the instruction completion signal to the S1 drive signal generation circuit after the waiting time set at the interval. The S1 drive signal generation circuit sends a control signal to the S1 group drive unit according to the instruction completion signal to control the switch group S1 to open.

[0068] It should be known that the above control process can be applied not only to the process of shutting down the photovoltaic string from normal operation, but also to the process of resuming normal operation of the photovoltaic string from shutdown. Under different working conditions of the photovoltaic string, the corresponding action of the switch group S2 is different; if the photovoltaic string is shut down, it can be seen from the above content that the switch group S1 is closed first, and then the corresponding action of the switch group S2 is to open, and finally the switch group S1 is opened; if the photovoltaic string resumes normal operation, it can be seen from the above content that the switch group S1 is closed first, and then the corresponding action of the switch group S2 is to close, and finally the switch group S1 is opened. For the sake of ease of understanding, the specific working process of the controller will be described in detail below, taking the need to shut down the photovoltaic string as an example.

[0069] like Fig.12 As shown, when the photovoltaic string needs to be shut down from normal operation, the communication circuit can receive a shutdown signal and output the shutdown signal to the S1 drive signal generation circuit. The S1 drive signal generation circuit can send a control signal PWM to the S1 group drive unit according to the received shutdown signal. S1 , so that the S1 drive unit is based on the control signal PWM S1 The switch devices of the driving switch group S1 are closed, and the S1 driving signal generating circuit forwards the shutdown signal to the first delay circuit. After receiving the shutdown signal, the first delay circuit can delay the shutdown signal to the S2 driving signal generating circuit by T1 time, and the S2 driving signal generating circuit can send a control signal PWM to the S2 group driving unit according to the received shutdown signal. S2 , so that the S2 drive unit is based on the control signal PWM S2The switch devices of the driving switch group S2 are turned off. At this time, the photovoltaic string can be considered to have completed the shutdown, so the S2 driving signal generation circuit can generate a shutdown completion signal and forward it to the second delay circuit. After receiving the shutdown completion signal, the second delay circuit can delay the shutdown completion signal to the S1 driving signal generation circuit by T2 time. The S1 driving signal generation circuit can send a new control signal PWM to the S1 group drive unit according to the received shutdown completion signal. S1 , so that the S1 drive unit is based on the new control signal PWM S1 The switching devices of the switch group S1 are driven to be turned off.

[0070] It should be noted that the specific structures and working principles of the communication circuit, S1 drive signal generating circuit, first delay circuit, S2 drive signal generating circuit and second delay circuit are well known to those skilled in the art, so they will not be elaborated here in detail.

[0071] The above describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and the specification only describe the principles of the present application. The present application may have various changes and improvements without departing from the spirit and scope of the present application, and these changes and improvements fall within the scope of the present application for which protection is sought. The scope of protection claimed by the present application is defined by the attached claims and their equivalents.

Claims

1. A photovoltaic rapid shutdown system, characterized in that: include: Switch group S1; each switch device of the switch group S1 is connected in parallel with a corresponding number of photovoltaic modules of the photovoltaic string; Switch group S2; the switch devices of the switch group S2 are respectively connected in series between adjacent photovoltaic components of the photovoltaic string; as well as Control module; the control module is respectively connected to the switch group S1 and the switch group S2 for control; When the photovoltaic string is in normal operation, the control module controls the switch group S2 to remain closed and controls the switch group S1 to remain open; When the photovoltaic string is shut down from normal operation, the control module is adapted to successively control the switch group S1 to close, control the switch group S2 to open, and control the switch group S1 to open again.

2. The photovoltaic rapid shutdown system according to claim 1, characterized in that: When the photovoltaic string is turned off and then operates normally, the control module is suitable for successively controlling the switch group S1 to close, controlling the switch group S2 to close, and controlling the switch group S1 to open.

3. The photovoltaic rapid shutdown system according to claim 2, characterized in that: When the photovoltaic string is switched between normal operation and shutdown, the control module is suitable for performing interval control on adjacent actions between the switch group S1 and the switch group S2.

4. The photovoltaic rapid shutdown system according to claim 3, characterized in that: The photovoltaic fast shutdown system further includes a plurality of voltage balancing circuits; in the switch group S1 and the switch group S2, the voltage balancing circuit is connected in parallel with at least all the switch devices of the switch group S2; The voltage balancing circuit adopts one of a passive RC circuit, an MOV resistor circuit, and a parallel circuit of the passive RC circuit and the MOV resistor circuit.

5. The photovoltaic rapid shutdown system according to claim 3, characterized in that: The control module comprises: S1 group driving unit; the S1 group driving unit is connected to each switch device of the switch group S1 for driving; S2 group driving unit; the S2 group driving unit is connected to each switch device of the switch group S2 for driving; and Controller; the controller is respectively connected to the S1 group drive unit and the S2 group drive unit for communication; The controller is suitable for receiving command signals for controlling photovoltaic strings and sending corresponding control signals to the S1 group drive unit and the S2 group drive unit respectively, so that the S1 group drive unit and the S2 group drive unit drive and control each switch device of the switch group S1 and each switch device of the switch group S2 respectively.

6. The photovoltaic rapid shutdown system according to claim 5, characterized in that: The controller includes a communication circuit, an S1 drive signal generating circuit, a first delay circuit, an S2 drive signal generating circuit and a second delay circuit; The controller performs the following control process according to the working instruction received by the communication circuit: The communication circuit is adapted to forward the received working instruction to the S1 drive signal generating circuit; The S1 drive signal generating circuit sends a control signal to the S1 group drive unit according to the working instruction to control the switch group S1 to close; The S1 driving signal generating circuit is further adapted to forward the received working instruction to the first delay circuit, so that the first delay circuit forwards the working instruction to the S2 driving signal generating circuit after a set waiting time; The S2 drive signal generating circuit sends a control signal to the S2 group drive unit according to the working instruction to control the switch group S2 to perform corresponding actions; The S2 drive signal generating circuit is further adapted to send an instruction completion signal to the second delay circuit, so that the second delay circuit forwards the instruction completion signal to the S1 drive signal generating circuit after a set waiting time; The S1 driving signal generating circuit sends a control signal to the S1 group driving unit according to the instruction completion signal to control the switch group S1 to be disconnected.

7. The photovoltaic rapid shutdown system according to claim 5, characterized in that: The S1 group driving unit and the S2 group driving unit both include a power amplifier circuit and an isolation circuit; The power amplifier circuit is suitable for receiving the control signal sent by the controller and amplifying the signal before outputting it to the isolation circuit; The isolation circuit is suitable for isolating the amplified control signal to output a driving signal corresponding to the number of switch devices in the switch group to each switch device in the switch group.

8. The photovoltaic rapid shutdown system according to any one of claims 1 to 7, characterized in that: Divide the photovoltaic components of the photovoltaic strings into multiple adjacent groups according to a set number; The number of switch devices in the switch group S1 is equal to the number of photovoltaic modules in the photovoltaic string, so that each switch device in the switch group S1 is connected in parallel to each photovoltaic module in the photovoltaic string; The number of switch devices in the switch group S2 is equal to the number of photovoltaic modules, so that each switch device in the switch group S2 is connected in series between two adjacent photovoltaic modules in the photovoltaic string.

9. The photovoltaic rapid shutdown system according to any one of claims 1 to 7, characterized in that: The photovoltaic components of the photovoltaic string are divided into a plurality of adjacent groups according to a set number, and the number of switch devices in the switch group S1 and the number of switch devices in the switch group S2 are both equal to the number of groups of the photovoltaic components; Each switch device of the switch group S1 is connected in parallel with each set number of photovoltaic modules in the photovoltaic string, and each switch device of the switch group S2 is connected in series between two adjacent photovoltaic modules in the photovoltaic string.

10. The photovoltaic rapid shutdown system according to claim 1, characterized in that: The photovoltaic fast shutdown system is externally arranged on the inverter of the photovoltaic system; or, the photovoltaic fast shutdown system is internally arranged on the inverter of the photovoltaic system.

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