Inverter and abnormal shutdown method and apparatus therefor, and photovoltaic system

Abstract

The present application relates to the technical field of photovoltaics, and provides an inverter and an abnormal shutdown method and apparatus therefor, and a photovoltaic system. For an inverter circuit, a switch module, and a controller of the present application, a plurality of switches are connected in series in the switch module, an input end of the inverter circuit is connected to a direct current source, an output end of the inverter circuit is connected to a power grid by means of the switch module, and a control end of at least one switch among the plurality of switches is independently connected to the controller. The switch module is configured to: when turned on, transmit an alternating current outputted by the output end of the inverter circuit to the power grid, and when turned off, suspend transmission of the alternating current outputted by the output end of the inverter circuit. The controller is configured to: when a short circuit occurs in the inverter, turn off a drive of the inverter and disconnect at least one switch, in the switch module, independently connected to the controller. Therefore, by controlling the switches, in the switch module, independently connected to the controller, connections to the inverter circuit and the power grid can be disconnected by means of the switch module, so that the problem of a short circuit of the inverter can be handled in time.

Description

An inverter and abnormal shutdown method and device thereof, and a photovoltaic system

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of the People's Republic of China on September 14, 2023, with application number 202311188081.8 and application name "A inverter and its abnormal shutdown method and device, a photovoltaic system", the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of photovoltaic technology, and in particular to an inverter and an abnormal shutdown method and device thereof, and a photovoltaic system. Background Art

[0003] Inverter short circuit, for example, busbar positive and negative poles short-circuited to ground, or photovoltaic panel cable insulation abnormalities to ground, will cause photovoltaic solar panel PV-to-ground short circuit, etc., which will damage the inverter and need to be shut down immediately.

[0004] Summary of the Invention

[0005] In view of this, embodiments of the present application provide an inverter and an abnormal shutdown method and device thereof, and a photovoltaic system, which aim to shut down the inverter in a timely manner and reduce damage to the inverter caused by an inverter short circuit.

[0006] In a first aspect, the present application provides an inverter, comprising: an inverter circuit, a switch module and a controller, wherein the switch module connects multiple switches in series, the input end of the inverter circuit is connected to a DC source, the output end of the inverter circuit is connected to a power grid through the switch module, and the control end of at least one switch among the multiple switches is independently connected to the controller; the inverter circuit is used to convert the DC power output by the DC source into AC power; the switch module is used to transmit the AC power output by the output end of the inverter circuit to the power grid when it is turned on, and to suspend the transmission of the AC power output by the output end of the inverter circuit when it is turned off; the controller is used to turn off the inverter drive when it is confirmed that a short circuit has occurred in the inverter, and disconnect at least one switch in the switch module that is independently connected to the controller.

[0007] Optionally, the inverter circuit is a multi-phase inverter circuit, and each phase output end of the multi-phase inverter circuit is connected to a switch module; the control end of each switch in each switch module is independently connected to the controller; or, the control end of the first switch in each switch module is independently connected to the controller, and the control end of the second switch in the same switch group is commonly connected to the controller, and the second switch in the same switch group corresponds one-to-one to the switch module included in the inverter; wherein, the first switch in each switch module is part of the switches included in the switch module, and the second switch is the switch other than the first switch among the switches included in the switch module.

[0008] Optionally, the control end of each switch in each switch module is independently connected to the controller, and each control end of the switch corresponds to a connecting line connected to the controller, and the connecting line is used to transmit the switch opening signal or the switch closing signal sent by the controller.

[0009] Optionally, the controller is also used to control the disconnection of a switch in the switch module corresponding to the phase electricity according to the current at the output end of each phase electricity in the inverter circuit; and simultaneously or sequentially send a switch disconnection signal to the closed switches in all the switch modules connected to the inverter circuit to control the disconnection of the closed switches in the switch modules connected to the inverter circuit.

[0010] Optionally, the control end of the first switch in each switch module is independently connected to the controller, and the control ends of the second switches in the same switch group are commonly connected to the controller. Then, the control end of each first switch corresponds to a connecting line connected to the controller, and the control end of the second switch in the same switch group is connected to the controller through the same connecting line, and the connecting line is used to transmit the switch disconnect signal or switch closing signal sent by the controller.

[0011] Optionally, each of the switch modules has a first switch; the controller is further used to control a first switch in the switch module corresponding to the phase electricity to be disconnected according to the current at the output end of each phase electricity in the inverter circuit, and then send a switch disconnection signal to the switch group included in the inverter to control the second switch included in the switch group to be disconnected.

[0012] Optionally, each switch module has at least two first switches; the controller is further used to control a first switch in the switch module corresponding to the phase electricity to be disconnected according to the current at the output end of each phase electricity in the inverter circuit, and then send a switch disconnection signal to the switch group and the closed first switch included in the inverter to control the second switch included in the switch group and the closed first switch to be disconnected.

[0013] Optionally, the controller is further used to select a switch that can serve as a preset switch other than the preset switch from the switch module corresponding to the preset switch as a new preset switch after determining that the use of the current preset switch meets the preset conditions; the preset conditions include a preset usage time or a preset number of uses, and the preset switch is a switch pre-set in the controller for controlling the shutdown of the switch module, and the preset switch is a switch separately configured with a connecting line connected to the controller.

[0014] Optionally, the inverter short circuit includes a short circuit of the inverter photovoltaic panel cable to the ground and a short circuit of the positive and negative poles of the bus to the ground; the controller is further used to confirm that the photovoltaic panel cable is short-circuited to the ground when the first abnormal condition of the inverter photovoltaic panel cable being short-circuited to the ground is met; and to confirm that the positive and negative poles of the bus are short-circuited to the ground when the second abnormal condition of the bus positive and negative poles being short-circuited to the ground is met; the first abnormal condition includes that at the same time, the absolute value of the vector sum of the current values ​​collected from the output ends of the N phases of the N-phase inverter is greater than a first threshold, N is greater than 1, and the first threshold is the maximum value of the absolute value of the vector sum of the current collection values ​​of the N phase circuits at the same time when the power converter is normal; or, the current collection values ​​of the output ends of the N phases of the N-phase alternating current are all positive, N is greater than 1. 1; or, the current collection values ​​of the output ends of any two phases of the N phases of the N-phase alternating current are positive, and N is greater than 2; or, the current collection value of the output end of at least one phase of the N phases exceeds a preset value, and the voltage collection value of the output end of the phase corresponding to the current collection value is positive, and the preset value is the current collection value of the output end of the phase when the power converter is operating normally; the current collection value is the average value or maximum value determined after multiple collections of the phase circuit according to the switching frequency of the first switch, and the multiple collections include collecting the instantaneous effective value of the current or collecting the instantaneous peak value of the current; the second abnormal condition includes that the voltage drop slope of the bus is greater than the voltage drop slope when the bus is operating normally, and the minimum value of the bus voltage is less than the inverter operating voltage.

[0015] In the second aspect, the present application also provides an inverter abnormal shutdown method, which is applied to the controller in the above-mentioned inverter, and the method includes: when it is determined that the inverter is short-circuited, turning off the inverter drive of the inverter; continuously collecting electrical parameters of the output end of each phase of the inverter circuit, the electrical parameters are one or more of voltage values ​​or current values; determining the zero-crossing moment of the current value of the phase electricity based on the collected electrical parameters of each phase electricity; based on the zero-crossing moment, disconnecting the preset switch in the switch module corresponding to the phase electricity, the preset switch is a switch pre-set in the controller for controlling the shutdown of the switch module, and the preset switch is a switch whose control end is independently connected to the controller.

[0016] Optionally, the inverter short circuit is a short circuit of the inverter photovoltaic panel cable to the ground; the determining of the zero-crossing moment of the current value of the phase electricity based on the electrical parameters collected from each phase electricity includes: determining the moment corresponding to the first change from a negative value to a positive value of the voltage value collected from the output end of the phase electricity as the first zero-crossing moment of the current value of the phase electricity; or, when the current value collected from the output end of the phase electricity shows a downward trend over time, determining the second zero-crossing moment of the current value of the phase electricity based on the slope of the downward trend, and subtracting the switch power-off delay time from the second zero-crossing moment to obtain the signal moment; disconnecting the preset switch in the switch module corresponding to the phase electricity based on the zero-crossing moment includes: sending a switch-off signal to the preset switch in the switch module corresponding to the phase electricity within a preset time length starting from the first zero-crossing moment or the signal moment to disconnect the preset switch, and the preset time length is the time length between the moment corresponding to the first change from a negative value to a positive value of the voltage value collected from the output end of the phase electricity to the moment corresponding to the first change from the positive value to a negative value.

[0017] Optionally, the inverter short circuit is a short circuit between the positive and negative poles of the busbar and the ground; the zero-crossing moment of the current value of the phase electricity is determined based on the electrical parameters collected for each phase electricity, including: when the current value collected at the output end of the phase electricity shows a downward trend over time, the zero-crossing moment of the current value of the phase electricity is determined according to the slope of the downward trend; the preset switch in the switch module corresponding to the phase electricity is disconnected according to the zero-crossing moment, including: subtracting the switch power-off delay time from the zero-crossing moment to obtain the signal moment, and determining the target current value corresponding to the signal moment according to the slope; when the absolute value of the difference between the collected current value and the target current value is less than the target threshold, a switch-off signal is sent to the preset switch in the switch module corresponding to the phase electricity to disconnect the preset switch, and the target threshold is the difference between the current values ​​collected twice adjacently.

[0018] In a third aspect, the present application also provides an inverter abnormal shutdown device, which is applied to the controller in the above-mentioned inverter, and the device includes: a processing unit, configured to shut down the inverter drive of the inverter when it is determined that the inverter is short-circuited; a collection unit, configured to continuously collect electrical parameters of the output end of each phase of the inverter circuit, and the electrical parameters are one or more of voltage values ​​or current values; a calculation unit, configured to determine the slope of the downward trend and the zero-crossing moment of the electrical parameters when the electrical parameters collected at the output end of each phase of the electricity show a downward trend; a control unit, configured to disconnect the preset switch in the switch module corresponding to the phase electricity according to the zero-crossing moment, the preset switch is pre-set in the controller, and is configured to control the shutdown of the switch module, and the preset switch is a switch whose control end is independently connected to the controller.

[0019] In a fourth aspect, the present application also provides a photovoltaic system comprising a solar panel string and an inverter, wherein the solar string is connected to the input end of the inverter and is configured to provide direct current (DC) power to the inverter; the output end of the inverter is connected to the power grid and is configured to convert the DC power of the DC power supply into AC power and transmit it to the power grid, and the inverter adopts one of the above-mentioned inverters.

[0020] The embodiments of the present application provide an inverter and its abnormal shutdown method and device, as well as a photovoltaic system. In the inverter of the present application, a switch module is connected in series with multiple switches, the input end of the inverter circuit is connected to the DC source, the output end of the inverter circuit is connected to the power grid through the switch module, and the control end of at least one of the multiple switches is independently connected to the controller. The controller is used to turn off the inverter drive when a short circuit occurs in the inverter, and disconnect at least one switch in the switch module that is independently connected to the controller. In this way, by controlling the switch in the switch module that is independently connected to the controller to disconnect, the connection between the inverter circuit and the power grid through the switch module can be disconnected, thereby reducing the damage to the inverter caused by the inverter short circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in this embodiment or the prior art, the following briefly introduces the drawings required for use in the embodiment or the prior art description. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0022] FIG1 is a schematic diagram of an inverter circuit provided in an embodiment of the present application;

[0023] FIG2 is a schematic diagram of another inverter circuit structure provided by the present application;

[0024] Figure 3 (af) is a schematic diagram of a connection structure between a controller and a switch via a connecting line provided by the present application;

[0025] FIG4 is a schematic diagram of another inverter circuit structure provided by the present application;

[0026] FIG5 is a flow chart of a method for abnormally shutting down an inverter provided in an embodiment of the present application;

[0027] FIG6 is a flow chart of an application method for abnormal inverter shutdown provided by an embodiment of the present application;

[0028] FIG7 is a schematic structural diagram of an inverter abnormal shutdown device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0029] Inverter short circuits can damage the inverter. For example, insulation issues with photovoltaic panel cables to ground have become an industry-wide problem for protective earthing (TN) systems, accounting for over half of all photovoltaic failures. However, when the insulation of the photovoltaic panel cables to ground is abnormal, a PV-to-ground short circuit can occur. This loop, indicated by the arrow in Figure 1, can damage the inverter. Therefore, it is necessary to shut down the inverter immediately.

[0030] Currently, after shutting down the inverter drive, it is necessary to disconnect the inverter's multiple phases. Figure 1 shows an inverter circuit diagram. Group D's main relays simultaneously disconnect K1, K3, and K5. Group F's main relays then simultaneously disconnect K2, K4, and K6, controlling the inverter's multiple phases. However, when disconnecting multiple phases simultaneously, due to the different phases of the three phases, a high current can flow through a relay when shutting down, potentially damaging it.

[0031] Based on the above problems, the present application sets up a switch module that can realize the sequential shutoff of each phase power output of the inverter. The circuit sets a switch module corresponding to the output end of each phase power. The switch module is connected in series with multiple switches. Each switch can be connected to the controller separately, or the control end of the first switch in each switch module is independently connected to the controller, and the control end of the second switch in the same switch group is commonly connected to the controller. The second switch in the same switch group corresponds one-to-one to the switch module included in the inverter. The controller can sequentially control the switches that are individually connected to the switch module to disconnect the switch module to avoid arcing. In addition, the present application shuts down the inverter drive and then disconnects the switch modules of each phase power in turn to avoid the photovoltaic solar panel PV-to-ground short circuit caused by abnormal insulation of the photovoltaic panel cable to the ground, which causes damage to the inverter.

[0032] In addition, multiple redundant switches can be set on each switch module, and the switches can be used alternately to increase the life of each switch.

[0033] Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0034] FIG2 is a schematic diagram of another inverter circuit structure provided by the present application. Referring to FIG2 , an inverter includes: an inverter circuit, a switch module, and a controller.

[0035] The switch module connects multiple switches in series, the input end of the inverter circuit is connected to the DC source, the output end of the inverter circuit is connected to the power grid through the switch module, and the control end of at least one switch among the multiple switches is independently connected to the controller.

[0036] A switch module is connected to the output end of each phase of the inverter circuit.

[0037] The inverter circuit can be a single-phase inverter circuit or a multi-phase inverter circuit. For example, the inverter shown in FIG2 is a three-phase inverter, and the inverter circuit is a three-phase inverter circuit. The three-phase inverter circuit in FIG2 is provided with a switching module group A, a switching module group B, and a switching module group C.

[0038] Each group of switch modules is connected in series with at least two switches. For example, the switch modules of group A are connected in series with switch K1 and switch K2 in sequence.

[0039] The input end of the inverter circuit is connected to a DC source, and the output end of the inverter circuit is connected to the power grid through a switch module.

[0040] The DC source may be powered by a solar panel string, or may be powered by other modules capable of providing DC power (such as a battery).

[0041] The output end of the inverter circuit is connected to the grid through a switch module. For example, after the switch module of group A is connected in series with K1 and K2, it is output to the grid through port A. Similarly, ports B and C also transmit the corresponding phase electricity to the grid. As shown in Figure 1, port A, port B, and port C are the ports that output three phase electricity to the grid respectively.

[0042] The inverter circuit is used to convert the DC power output by the DC source into AC power.

[0043] The switch module is used to transmit the AC power outputted by the output end of the inverter circuit to the power grid when it is turned on, and to suspend the transmission of the AC power outputted by the output end of the inverter circuit when it is turned off.

[0044] The controller is used to shut down the inverter drive and disconnect at least one switch in the switch module that is independently connected to the controller when a short circuit occurs in the inverter.

[0045] Exemplarily, as shown in FIG2 , according to the current at the output end of each phase of the inverter circuit, one switch in the switch module corresponding to the phase is controlled to be disconnected.

[0046] According to the inverter described above, a switch module in the inverter of the present application connects multiple switches in series, the input end of the inverter circuit is connected to a DC source, the output end of the inverter circuit is connected to the power grid through the switch module, and the control end of at least one of the multiple switches is independently connected to a controller. The control end of at least one of the multiple switches is independently connected to the controller. This allows, after the inverter drive is shut down, the switch in the switch module independently connected to the controller can be controlled to disconnect the connection between the inverter circuit and the power grid through the switch module, thereby reducing damage to the inverter caused by a short circuit.

[0047] In the embodiment of the present application, there are multiple possible implementations for connecting the controller in FIG2 with the switch on the switch module, which are described below. It should be noted that the implementations described below are only exemplary and do not represent all implementations of the embodiment of the present application.

[0048] In one possible implementation, the inverter may be a single-phase inverter circuit, with each phase corresponding to a switch module. The control terminals of the switches included in the switch module are independently connected to a controller via a connection line. The controller may send a switch-off signal to a preset switch in the switch module to control the switch module to be turned off. The controller may then send a switch-off signal to the closed switches in the switch module to open all closed switches.

[0049] In another implementation, the inverter circuit is a multi-phase inverter circuit, and each phase output end of the multi-phase inverter circuit is connected to a switch module.

[0050] In the first possible implementation.

[0051] Referring to FIG. 2 , the control end of each switch in each switch module is independently connected to the controller.

[0052] This allows the controller to select a preset switch to shut down each switch module (disconnecting the corresponding phase power transmission path to the grid) before controlling it to shut down (disconnecting the corresponding phase power transmission path to the grid). This is based on the cumulative time or number of times each switch in the switch module has been used to shut down the switch module. Of course, the preset switch can also be manually set in the controller. After the controller sets the preset switch for each switch module, when the controller wants to shut down a switch module, it sends a switch-off signal to the preset switch of the switch module to control the switch module to shut down.

[0053] For example, for the switch module of group A in Figure 2, K1 can be selected as the preset switch, or K2 can be selected as the preset switch. The alternating use of K1 and K2 can extend the service life of the switch module of group A. This is because the switch in this application is a relay. When the relay is turned off, it is susceptible to current shock, which in turn affects the service life of the relay. By adjusting and replacing the preset switch in the switch module through the controller, the service life of the switch module can be extended and the maintenance of the switch module can be reduced.

[0054] Corresponding to the connection method between the above controller and the switch on the switch module, the specific setting method of the connection line is provided as follows:

[0055] The control end of each switch corresponds to a connecting line connected to the controller, and the connecting line is used to transmit a switch opening signal or a switch closing signal sent by the controller.

[0056] For example, as shown in Figure 2, the controller sets a connection line corresponding to each of K1, K2, K3, K4, K5, and K6. The controller can send a switch opening signal or a switch closing signal to K1 through the connection line corresponding to K1, and the same applies to K2, K3, K4, K5, and K6.

[0057] For example, based on the current of the phase connected to the switch modules in group A, to control the disconnection of one of the switches in group A, the controller can pre-configure the switch, such as K1. The controller then sends a switch disconnect signal to K1 via the corresponding connection line, disconnecting K1. If the switch module in group A, which has been connected after repeated use, disconnects, the controller can adjust K1 to K2, thereby extending the service life of each switch and reducing circuit maintenance.

[0058] Furthermore, the controller is also used to control the disconnection of a switch in the switch module corresponding to the phase electricity according to the current at the output end of each phase electricity in the inverter circuit; and simultaneously or sequentially send a switch disconnection signal to the closed switches in all the switch modules connected to the inverter circuit to control the disconnection of the closed switches in the switch modules connected to the inverter circuit.

[0059] For example, based on the current at the output end of each phase of the inverter circuit, one of the switches in the switch module corresponding to that phase is controlled to be disconnected. For example, in FIG2 , based on the current of each phase, the preset switch K1 in the switch module of group A is controlled to be disconnected, the preset switch K4 in the switch module of group B is controlled to be disconnected, and the preset switch K5 in the switch module of group C is controlled to be disconnected. Finally, the controller simultaneously sends a switch disconnection signal to the corresponding switch through the connection line of K2, the connection line of K3, and the connection line of K6, and uses K2, K3, and K6 to disconnect simultaneously. Of course, the switch disconnection signal can also be sent to the corresponding switch through the connection line of K2, the connection line of K3, and the connection line of K6 in sequence, and uses K2, K3, and K6 to disconnect in sequence.

[0060] Or, in a second possible implementation.

[0061] The control terminals of the first switches in each switch module are independently connected to the controller, while the control terminals of the second switches in the same switch group are commonly connected to the controller. The second switches in the same switch group correspond one-to-one with the switch modules included in the inverter. The first switches in each switch module are part of the switches included in the switch module, and the second switches are all switches in the switch module except the first switches.

[0062] Illustratively, each switch module includes a first switch. The controller is further configured to, based on the current at the output terminal of each phase of the inverter circuit, control a first switch in the switch module corresponding to the phase to be disconnected, and then send a switch disconnection signal to the switch group included in the inverter to control a second switch included in the switch group to be disconnected.

[0063] For example, see FIG. 3 (a) to (f), which are schematic diagrams of a connection structure between a controller and a switch via a connecting line provided by the present application.

[0064] In Figure 3(a), K2, K3, and K5 are the first switches, and are connected to the controller via a corresponding connecting line respectively. K1, K4, and K6 are the second switches, and K1, K4, and K6 are connected to the controller via the same connecting line. The controller controls K2, K3, and K5 to turn off one by one according to the current at the output end of each phase of the inverter circuit, and then controls K1, K4, and K6 to turn off simultaneously via the same connecting line.

[0065] In Figure 3(b), K1, K4, and K5 are the first switches, and are connected to the controller via a corresponding connecting line respectively. K2, K3, and K6 are the second switches, and K2, K3, and K6 are connected to the controller via the same connecting line. The controller controls K1, K4, and K5 to turn off one by one according to the current at the output end of each phase of the inverter circuit, and then controls K2, K3, and K6 to turn off simultaneously via the same connecting line.

[0066] In Figure 3(c), K1, K3, and K6 are the first switches, and are connected to the controller via a corresponding connecting line respectively. K2, K4, and K5 are the second switches, and K2, K4, and K5 are connected to the controller via the same connecting line. The controller controls K1, K3, and K6 to turn off one by one according to the current at the output end of each phase of the inverter circuit, and then controls K2, K4, and K5 to turn off simultaneously via the same connecting line.

[0067] In Figure 3(d), K2, K4, and K5 are the first switches, and are connected to the controller via a corresponding connecting line respectively. K1, K3, and K6 are the second switches, and K1, K3, and K6 are connected to the controller via the same connecting line. The controller controls K2, K4, and K5 to turn off one by one according to the current at the output end of each phase of the inverter circuit, and then controls K1, K3, and K6 to turn off simultaneously via the same connecting line.

[0068] In Figure 3(e), K1, K4, and K6 are the first switches, and are connected to the controller via a corresponding connecting line respectively. K2, K3, and K5 are the second switches, and K2, K3, and K5 are connected to the controller via the same connecting line. The controller controls K1, K4, and K6 to turn off one by one according to the current at the output end of each phase of the inverter circuit, and then controls K2, K3, and K5 to turn off simultaneously via the same connecting line.

[0069] In Figure 3(f), K2, K3, and K6 are the first switches, and each is connected to the controller via a corresponding connecting line. K1, K4, and K5 are the second switches, and K1, K4, and K5 are connected to the controller via the same connecting line. The controller controls K2, K3, and K6 to turn off one by one according to the current at the output end of each phase of the inverter circuit, and then controls K1, K4, and K5 to turn off simultaneously via the same connecting line.

[0070] Based on the above example, after any switch can be selected from each switch module and set as a preset switch, the control ends of the remaining switches can be connected to the controller through the same connection line, saving the number of connection line configurations.

[0071] Illustratively, each switch module includes a plurality of first switches. The controller is further configured to, based on the current at the output end of each phase of the inverter circuit, control a first switch in the switch module corresponding to the phase to be opened, and then send a switch opening signal to the switch group and the closed first switch included in the inverter to control the second switch in the switch group and the closed first switch to be opened.

[0072] For example, see FIG4 for another schematic diagram of an inverter circuit structure provided by the present application. The first switch in the switch module of group A may include Kx1 and Kx2, which respectively correspond to two connecting lines connected to the controller (of course, the switch module of group A may also be provided with multiple other first switches), the first switch in the switch module of group B may include Ky1 and Ky2, which respectively correspond to two connecting lines connected to the controller (of course, the switch module of group B may also be provided with multiple other first switches), and the first switch in the switch module of group C may include Kz1 and Kz2, which respectively correspond to two connecting lines connected to the controller (of course, the switch module of group C may also be provided with multiple other first switches). Kxm in the switch module of group A, Kym in the switch module of group B, and Kzm in the switch module of group C form a switch group (of course, multiple other switch groups may also be provided accordingly), and K7, K8, and K9 in the switch group are all connected to the controller through the same connecting line.

[0073] For example, based on the current at the output end of each phase of the inverter circuit, the preset switch in the switch module corresponding to that phase is controlled to be disconnected. For example, in FIG3 , based on the circuits of each phase, the first switch KX1 in the switch module of group A is controlled to be disconnected, the first switch Ky1 in the switch module of group B is controlled to be disconnected, and the first switch Kz1 in the switch module of group C is controlled to be disconnected. Finally, the controller simultaneously sends a switch disconnection signal to the corresponding switch or switch group via the connection line Kx2, the connection line Ky2, the connection line Kz2, and the connection line of the switch group, thereby simultaneously disconnecting Kx2, Ky2, Kz2, and Kxm, Kym, and Kzm in the switch group. Of course, the controller can also sequentially send switch disconnection signals via the connection line Kx2, the connection line Ky2, the connection line Kz2, and the connection line of the switch group, thereby disconnecting Kx2, Ky2, Kz2, and the switch group in sequence, wherein (Kxm, Kym, and Kzm in the switch group are disconnected simultaneously).

[0074] In addition, the controller is also used to select another switch from the switch module of the preset switch as a new preset switch after determining that the use of the current preset switch meets the preset conditions; the preset conditions include a preset usage time or a preset number of uses. The preset switch is a switch pre-set in the controller for controlling the shutdown of the switch module. The preset switch is a switch separately configured with a connecting line connected to the controller.

[0075] For example, through the setting of the controller, the first switch Kx1 in the above-mentioned group A switch module is used as a preset switch. After the cumulative usage time or number of uses of Kx1 exceeds the preset, Kx2 can be replaced as a new preset switch to disconnect the group A switch module and extend the service life of the switch. Similarly, Ky1 and Ky2 can be replaced, and Kz1 and Kz2 can be replaced.

[0076] Based on the above inverter, the controller can be used to determine if the inverter is short-circuited and abnormal. The specific implementation method is as follows:

[0077] Inverter short circuit includes inverter photovoltaic panel cable short circuit to ground, bus positive and negative pole short circuit to ground.

[0078] The controller is further configured to confirm that the inverter photovoltaic panel cable is short-circuited to the ground when the first abnormal condition of the inverter photovoltaic panel cable being short-circuited to the ground is met; and to confirm that the positive and negative poles of the busbar are short-circuited to the ground when the second abnormal condition of the busbar positive and negative poles being short-circuited to the ground is met.

[0079] The first abnormal condition includes that at the same time, the absolute value of the vector sum of the current values ​​collected from the output terminals of the N phases of the N-phase inverter is greater than a first threshold value, N is greater than 1, and the first threshold value is the maximum absolute value of the vector sum of the current collection values ​​of the N phase circuits at the same time when the power converter is normal; or, the current collection values ​​of the output terminals of the N phases of the N-phase alternating current are all positive, N is greater than 1; or, the current collection values ​​of the output terminals of any two phases of the N phases of the N-phase alternating current are all positive, N is greater than 2; or, the current collection value of the output terminal of at least one phase of the N phases exceeds a preset value, and the voltage collection value of the output terminal of the phase corresponding to the current collection value is positive, and the preset value is the current collection value of the output terminal of the phase when the power converter is operating normally; the current collection value is the average value or maximum value determined after multiple collections of the phase circuit according to the switching frequency of the first switch, and the multiple collections include collecting the instantaneous effective value of the current or collecting the instantaneous peak value of the current;

[0080] The second abnormal condition includes that the voltage drop slope of the bus is greater than the voltage drop slope when the bus operates normally, and the minimum value of the bus voltage is less than the inverter operating voltage.

[0081] Based on the above-mentioned inverter, referring to the flowchart of a method for abnormal shutdown of the inverter shown in FIG5 , the present application further provides a method for abnormal shutdown of the inverter, which is applied to the controller in the above-mentioned inverter, specifically comprising:

[0082] S501 : When it is determined that the inverter is short-circuited, turn off the inverter drive of the inverter.

[0083] Inverter short circuit may include busbar short circuit, photovoltaic panel cable short circuit to ground, etc.

[0084] Shut down the inverter drive, suspend DC to AC conversion, and protect the inverter components.

[0085] S502: Continuously collect electrical parameters of the output end of each phase of the inverter circuit, where the electrical parameters are one or more of voltage values ​​and current values.

[0086] Exemplarily, continuously collecting the electrical parameters of the output terminal of each phase of the inverter circuit may be collecting current values ​​multiple times within one cycle of the phase.

[0087] S503: Determine the zero-crossing moment of the current value of each phase according to the electrical appliance parameters collected from the phase.

[0088] S504. Disconnect the preset switch in the switch module corresponding to the phase electricity according to the zero-crossing moment. The preset switch is a switch pre-set in the controller for controlling the switch module to turn off. The preset switch is separately configured with a connection line connected to the controller.

[0089] According to steps S501-S504, the present application determines that the inverter is short-circuited, shuts down the inverter drive, suspends DC-to-AC conversion, and safely shuts off the first switch of each phase when the electrical parameter of each phase crosses zero, preventing arcing. This insulates the photovoltaic panel cables from ground, protecting the inverter from damage, while also reducing the relay's breaking current and improving its reliability.

[0090] In the embodiment of the present application, there are multiple possible implementations for determining whether the inverter is short-circuited in step S501 in FIG5 , which are described below. It should be noted that the implementations described below are only exemplary and do not represent all implementations of the embodiment of the present application.

[0091] In a possible implementation, determining that the inverter is short-circuited includes determining that a photovoltaic panel cable of the inverter is short-circuited to ground.

[0092] Specifically, the method for determining whether a photovoltaic panel cable is short-circuited to ground includes:

[0093] In one possible implementation, A1, at the same time, the absolute value of the vector sum of the current values ​​collected from the output terminals of N phases of an N-phase inverter is greater than a first threshold, and N is greater than 1. The first threshold is the maximum absolute value of the vector sum of the current values ​​collected from the N phase circuits at the same time when the power converter is normal.

[0094] For example, taking the three-phase inverter in Figure 2 as an example, when the inverter is operating normally, the vector sum of the three-phase currents of the three-phase alternating current of the inverter is 0. However, when the insulation of the photovoltaic panel cable to the ground is abnormal, as shown in Figure 2, a photovoltaic solar panel PV-to-ground short-circuit loop is generated (the loop formed by the flow direction indicated by the arrow in Figure 2), and the three phases are connected through the inverter bridge arm diode. The diode has a single-phase conductive characteristic. The current of the phase with the larger current in the three phase circuits will flow through the diode into the other two phase circuits, making the three-phase vector sum not 0. Therefore, the absolute value of the vector sum of the current collection values ​​of the three phase circuits of the three-phase alternating current at the same time is greater than the first threshold value, and it is determined that the power converter has an abnormality. The first threshold value is the maximum value of the absolute value of the vector sum of the current collection values ​​of the three phase circuits at the same time when the power converter is normal.

[0095] or,

[0096] In one possible implementation method A2, the current collected values ​​at the output ends of the N phases of the N-phase AC power are all positive, and N is greater than 1; or, the current collected values ​​at the output ends of any two phases of the N phases of the N-phase AC power are all positive, and N is greater than 2.

[0097] For example, taking the three-phase inverter in FIG2 as an example, if the phase angle of the three-phase current of the inverter is abnormal, it can be confirmed that the inverter is abnormal and needs to be shut down.

[0098] or,

[0099] A possible implementation method A3 is that the current collection value of the output end of at least one phase of the N phases exceeds a preset value, and the voltage collection value of the output end of the phase corresponding to the current collection value is positive. The preset value is the current collection value of the output end of the phase when the power converter is operating normally.

[0100] The current acquisition value is an average value or a maximum value determined after multiple acquisitions of the phase electrical circuit according to the switching frequency of the first switch. The multiple acquisitions include acquiring the instantaneous effective value of the current or acquiring the instantaneous peak value of the current.

[0101] In another possible implementation, determining that the inverter is short-circuited includes determining that a positive electrode and a negative electrode of a bus are short-circuited to ground.

[0102] Specifically, the method for determining whether the positive and negative electrodes of the busbar are short-circuited to ground includes:

[0103] One possible implementation method B is that the bus voltage drop slope is greater than the bus voltage drop slope during normal operation, and the minimum value of the bus voltage is less than the inverter operating voltage.

[0104] Based on the two aforementioned implementations for determining an inverter short circuit, different implementations are provided for steps S503-S504. First, when the inverter short circuit is determined to be a photovoltaic panel cable short to ground, the specific implementations of steps S503-S504 in FIG. 5 are described below. It should be noted that the implementations described below are merely exemplary and do not represent all implementations of the embodiments of this application.

[0105] According to the electrical parameters collected from each phase, the zero-crossing moment of the current value of the phase is determined, including:

[0106] The controller determines the moment when the voltage value collected at the output end of the phase electricity changes from a negative value to a positive value for the first time as the zero-crossing moment 1 of the current value of the phase electricity.

[0107] Alternatively, when the current value collected by the controller at the output end of the phase electricity shows a downward trend over time, the zero-crossing time 2 of the phase current value is determined according to the slope of the downward trend, and the signal time is obtained by subtracting the switch power-off delay time from the zero-crossing time 2.

[0108] A method for determining that the collected current value shows a downward trend over time may be that the current value collected later minus the current value collected earlier is a negative number.

[0109] The slope of the decrease can be determined by a fitting curve formed based on the collected current values, or by calculating the coordinates of the two collected current values ​​in a coordinate system of current value and time. The absolute value of the latter current value of the two current values ​​is smaller than the absolute value of the former current value.

[0110] The power-off delay is set based on the mechanical time required for the relay to shut down. The controller sends a switch-off signal to the preset switch, triggering the preset switch (relay) to shut down. After the mechanical time, the relay shuts off at or near zero. Each phase of power is disconnected when the electrical parameters reach the zero-crossing point that safely disconnects the relay. This reduces the impact of high current on the relay contacts, prevents arcing, and protects the switch.

[0111] According to the zero-crossing moment, the preset switch in the switch module corresponding to the phase power is disconnected, including:

[0112] The controller sends a switch-off signal to the preset switch in the switch module corresponding to the phase electricity within a preset time length starting from the zero-crossing moment or the signal moment, and disconnects the preset switch. The preset time length is the time length between the moment when the voltage value collected at the output end of the phase electricity changes from a negative value to a positive value for the first time and the moment when the voltage value collected at the output end of the phase electricity changes from a positive value to a negative value for the first time.

[0113] For example, referring to Figure 2 , an inverter short circuit occurs when the photovoltaic panel cable is shorted to ground. When the voltage is positive, the diode is cut off, and the current is zero. From the moment the voltage value collected at the output of the corresponding phase first changes from negative to positive to the moment the voltage value collected at the output of the corresponding phase first changes from positive to negative, the voltage is positive, and the diode is cut off. During this period, the current is at its lowest value and remains at the zero-crossing moment. Therefore, the preset switch can be opened within a preset time period starting from the zero-crossing moment or the signal moment.

[0114] In the embodiment of the present application, when it is determined that the inverter short circuit is a short circuit between the positive and negative poles of the busbar, the specific implementation methods of steps S503-S504 in Figure 5 are described below. It should be noted that the implementation methods given in the following description are only exemplary and do not represent all implementation methods of the embodiment of the present application.

[0115] According to the electrical parameters collected from each phase, the zero-crossing moment of the current value of the phase is determined, including:

[0116] When the current value collected by the controller at the output end of the phase electricity shows a downward trend over time, the zero-crossing moment of the current value of the phase electricity is determined according to the slope of the downward trend;

[0117] A method for determining that the electrical parameter is in a downward trend may be that the current value collected later minus the current value collected earlier is a negative number.

[0118] The slope of the decrease can be determined by a fitting curve formed based on the collected current values, or by calculating the coordinates of the two collected current values ​​in a coordinate system of current value and time. The absolute value of the latter current value of the two current values ​​is smaller than the absolute value of the former current value.

[0119] According to the zero-crossing moment, the preset switch in the switch module corresponding to the phase power is disconnected, including:

[0120] The controller subtracts the switch power-off delay time from the zero-crossing time to obtain the signal time, and determines the target current value corresponding to the signal time based on the slope;

[0121] When the absolute value of the difference between the collected current value and the target current value is less than the target threshold, the controller sends a switch-off signal to the preset switch in the switch module corresponding to the phase current to disconnect the preset switch. The target threshold is the difference between the current values ​​collected twice adjacently.

[0122] The power-off delay is set based on the mechanical time required for the relay to shut down. The controller sends a switch-off signal to the preset switch, triggering the preset switch (relay) to shut down. After the mechanical time, the relay shuts off at or near zero. Each phase is disconnected when the electrical parameters reach zero, which safely disconnects the relay, preventing arcing and protecting the switch.

[0123] In the embodiment of the present application, after disconnecting the preset switch in the switch module corresponding to the phase power in step S504 in FIG. 5 , there are multiple possible implementations, which are described below. It should be noted that the implementations described below are only exemplary and do not represent all implementations of the embodiment of the present application.

[0124] In one possible implementation, the inverter includes at least one switch module, which includes a plurality of switches individually connected to the controller, and after disconnecting a preset switch, further includes:

[0125] At the same time or in sequence, a switch opening signal is sent to the closed switch to control the switch to open, and the connection line connecting the switch and the controller corresponds to the switch one by one.

[0126] In a possible implementation, the inverter includes a switch group, and after a preset switch is disconnected, further includes:

[0127] A switch disconnection signal is sent to a switch group included in the inverter to control the switches included in the switch group to disconnect.

[0128] 2 to 4 , after the inverter sequentially controls and turns off the preset switches in the switch module, the remaining switch groups and / or closed switches also need to be turned off.

[0129] For example, referring to FIG4 , according to the circuits of each phase electricity, Kx1 in the switch module of group A is controlled to be disconnected, Ky2 in the switch module of group B is controlled to be disconnected, and Kz1 in the switch module of group C is controlled to be disconnected (Kx1, Ky2, and Kz1 are respectively the preset switches of the corresponding switch modules in the controller). Finally, the controller simultaneously sends a switch disconnection signal to the closed switches (such as Kx2, Ky1, and Kz2) that are separately configured with connecting lines and the connecting lines of the switch group, to the corresponding switches or switch groups, so that the closed switches and the closed switches in the switch group are disconnected at the same time. Of course, the controller can also send switch disconnection signals to the closed switches and switch groups that are separately configured with connecting lines in sequence, and use the closed switches and switch groups to disconnect in sequence, wherein the closed switches in the switch group are disconnected at the same time).

[0130] In addition, during the switch closing time, when the switch module turns on the inverter circuit and connects to the grid, the second switch in the control switch group can be closed at the same time, and then the switches separately configured with connecting lines can be controlled to be turned off at the same time or in sequence.

[0131] Furthermore, after determining that the use of the current preset switch meets the preset conditions, the controller selects another switch from the switch module of the preset switch as a new preset switch; the preset conditions include a preset usage time or a preset number of uses, and the switch module includes multiple switches individually connected to the controller.

[0132] As shown in FIG2 , a three-phase inverter is shown. The three phases of the three-phase AC power output circuit correspond to three output ports (ports A, B, and C are used as an example in FIG2 ), respectively, for outputting the three-phase AC power. Each of the three output ports is provided with a switch module that controls the output of the corresponding phase (in FIG2 , port A corresponds to switch module group A, port B corresponds to switch module group B, and port C corresponds to switch module group C). In each switch module in the controller, one switch is selected (each switch is individually configured with a connection line connected to the controller) as the default switch, and the remaining switches can be used as backup switches (in FIG2 , taking group A as an example, if relay K1 is the default switch, then K2 is the backup switch; if relay K2 is the default switch, then K1 is the backup switch; the same applies to groups B and C). The backup switches can subsequently replace the default switches as the new default switches and require separate connection lines to the controller.

[0133] For example, when a preset switch in the inverter has been used for a preset duration or a preset number of times, one of the backup switches can be selected from the switch module corresponding to the preset switch as the new preset switch for use. Multiple first switches are set for each phase of electricity, which can be used alternately to extend the service life of each relay switch. (For example, in Figure 2, if K1, K4, and K5 are preset switches, then K2, K3, and K6 are backup switches. When K1, K4, and K5 have been used as preset switches for a preset duration or a preset number of times, K2, K3, and K6 can be switched as the new preset switches, and K1, K3, and K5 can be used as backup switches.)

[0134] The above is some specific implementation of an inverter and method provided by the embodiment of the present application. Based on this, combined with the inverter provided in FIG4 , the present application also provides a corresponding application method for abnormal shutdown of the inverter. Referring to the flow diagram of the application method for abnormal shutdown of the inverter shown in FIG6 , the application method for abnormal shutdown of the inverter specifically includes:

[0135] S601: When determining that a photovoltaic panel cable is short-circuited to ground, the controller turns off the inverter drive of the inverter.

[0136] Exemplarily, methods A1-A3 and method B may be used to determine the inverter short-circuit type.

[0137] The inverter driver includes an inverter circuit of an inverter.

[0138] S602: The controller continuously collects the current value of the output terminal of each phase of the inverter circuit.

[0139] As shown in FIG4 , the current values ​​of each phase can be collected at ia, ib and ic respectively.

[0140] For example, multiple current value acquisitions may be performed in each cycle of the phase electricity.

[0141] S603. When the controller detects that the current value of ia is decreasing over time, it determines the zero-crossing moment of the electrical parameter based on the slope of the downward trend, subtracts the switch power-off delay time from the zero-crossing moment to obtain the signal moment, and determines the target current value corresponding to the signal moment based on the slope.

[0142] When the photovoltaic panel cable is short-circuited to the ground (because the diode is cut off, there is no negative current value), the current value at the zero-crossing moment can be the moment corresponding to 0, or it can be any moment corresponding to an upper and lower fluctuation range where the current value drops to the minimum value.

[0143] In a possible implementation, each current value ia collected over time is plotted to form a time-current value fitting curve, the slope of the curve is determined, and the zero-crossing moment of the electrical parameter is predicted.

[0144] S604 : When the absolute value of the difference between the current value collected by ia and the target current value is less than the target threshold, the controller sends a switch-off signal to the preset switch Kx1 in the switch module corresponding to the phase current to disconnect the preset switch Kx1 .

[0145] The target threshold value may be the difference between two adjacent current values ​​collected. The collection may be multiple collections in one cycle of the phase current, with the collection interval being the same.

[0146] S605: When the controller detects that the current value of ib is decreasing over time, it determines the zero-crossing moment of the electrical parameter based on the slope of the decreasing trend, subtracts the switch power-off delay time from the zero-crossing moment to obtain the signal moment, and determines the target current value corresponding to the signal moment based on the slope;

[0147] S606: When the absolute value of the difference between the current value collected by ib and the target current value is less than the target threshold, the controller sends a switch-off signal to the preset switch Ky2 in the switch module corresponding to the phase current to disconnect the preset switch Ky2.

[0148] S607. When the controller detects that the current value of IC is decreasing over time, it determines the zero-crossing moment of the electrical parameter according to the slope of the downward trend, subtracts the switch power-off delay time from the zero-crossing moment to obtain the signal moment, and determines the target current value corresponding to the signal moment according to the slope.

[0149] S608 , when the absolute value of the difference between the current value collected by IC and the target current value is less than the target threshold, the controller sends a switch-off signal to the preset switch Kz1 in the switch module corresponding to the phase current to disconnect the preset switch Kz1 .

[0150] S609: The controller sends a switch disconnection signal to the closed switch that is individually configured with a connecting line and the switch group at the same time, so that the closed switch that is individually configured with a connecting line and the switches in the switch group are disconnected at the same time.

[0151] S610: After the controller determines that the cumulative continuous use times of the current preset switch Kx1 reaches the preset use times of 50 times, Kx2 is selected as the new preset switch. If the controller determines that the cumulative continuous use times of the current preset switches Ky2 and Kz1 have not reached the preset use times of 50 times, Ky2 and Kz1 continue to be the preset switches.

[0152] The above are some specific implementations of an inverter and a method thereof provided in the embodiments of the present application. Based on this, the present application also provides a corresponding inverter abnormal shutdown device. The following introduces an inverter provided in the embodiments of the present application.

[0153] Referring to FIG. 7 , a schematic structural diagram of an inverter abnormal shutdown device is shown. The inverter abnormal shutdown device is applied to the controller in the above-mentioned inverter, and the device includes:

[0154] The processing unit 701 is configured to shut down the inverter drive of the inverter when determining that the inverter is short-circuited;

[0155] The collecting unit 702 is configured to continuously collect electrical parameters of the output terminal of each phase of the inverter circuit, where the electrical parameters are one or more of voltage values ​​and current values;

[0156] The calculation unit 703 is configured to determine the slope of the downward trend and the zero-crossing time of the electrical parameter when the electrical parameter collected from the output end of each phase of electricity shows a downward trend;

[0157] The control unit 704 is configured to disconnect the preset switch in the switch module corresponding to the phase electricity according to the zero-crossing moment. The preset switch is pre-set in the controller and is configured to control the switch module to shut down. The preset switch is separately configured with a connection line connected to the controller.

[0158] According to the above-mentioned inverter abnormal shutdown device, when the processing unit 701 determines that an abnormality occurs, it shuts down the inverter drive, and then uses the acquisition unit 702, the calculation unit 703 and the control unit 704 to disconnect the switches in the switch modules of each phase electricity in turn according to the zero-crossing moment of the current value of each phase electricity, so as to avoid switch arcing, avoid inverter short circuit, and cause damage to the inverter.

[0159] In one possible implementation, determining whether a photovoltaic panel cable of an inverter is short-circuited to ground; the processing unit 701 is configured to determine whether the photovoltaic panel cable is short-circuited to ground when the absolute value of the vector sum of current values ​​collected from the output terminals of N phases of an N-phase inverter at the same time is greater than a first threshold, where N is greater than 1, and the first threshold is the maximum absolute value of the vector sum of the current collection values ​​of the N phase circuits at the same time when the power converter is normal; or, the current collection values ​​of the output terminals of N phases of N-phase alternating current are all positive, where N is greater than 1; or, the current collection values ​​of the output terminals of any two phases of N phases of N-phase alternating current are all positive, where N is greater than 2; or, the current collection value of the output terminal of at least one phase of the N phases exceeds a preset value, and the voltage collection value of the output terminal of the phase corresponding to the current collection value is positive, where the preset value is the current collection value of the output terminal of the phase when the power converter is operating normally; the current collection value is an average value or a maximum value determined after multiple collections of the phase circuit according to the switching frequency of the first switch, the multiple collections including collecting the instantaneous effective value of the current or collecting the instantaneous peak value of the current, to determine whether the photovoltaic panel cable is short-circuited to ground.

[0160] Furthermore, the calculation unit 703 is also configured to determine the moment corresponding to the first time the voltage value collected at the output end of the phase electricity changes from a negative value to a positive value as the zero-crossing moment one of the current value of the phase electricity; or, when the current value collected at the output end of the phase electricity by the controller shows a downward trend over time, the controller determines the zero-crossing moment two of the current value of the phase electricity according to the slope of the downward trend, and subtracts the switch power-off delay time from the zero-crossing moment two to obtain the signal moment.

[0161] The control unit 704 is also configured to send a switch-off signal to the preset switch in the switch module corresponding to the phase electricity within a preset time length starting from the zero-crossing moment or the signal moment, thereby disconnecting the preset switch. The preset time length is the time length between the moment when the voltage value collected at the output end of the phase electricity changes from a negative value to a positive value for the first time and the moment when the voltage value collected at the output end of the phase electricity changes from the positive value to a negative value for the first time.

[0162] In another possible implementation, the inverter short circuit is determined to be a short circuit between the positive and negative poles of the busbar and the ground; the processing unit 701 is configured to determine that the positive and negative poles of the busbar are short-circuited to the ground when the slope of the busbar voltage drop is greater than the slope of the voltage drop during normal operation of the busbar, and the minimum value of the busbar voltage is less than the inverter operating voltage.

[0163] Furthermore, the calculation unit 703 is configured to determine the zero-crossing moment of the current value of the phase electricity according to the slope of the downward trend when the current value collected at the output end of the phase electricity shows a downward trend over time;

[0164] The control unit 704 is configured to obtain a signal time by subtracting the switch power-off delay time from the zero-crossing time, and determine a target current value corresponding to the signal time according to the slope;

[0165] When the absolute value of the difference between the collected current value and the target current value is less than the target threshold, the controller sends a switch-off signal to the preset switch in the switch module corresponding to the phase electricity to disconnect the preset switch. The target threshold is the difference between the current values ​​collected twice adjacently.

[0166] In another possible implementation, the controller is further configured to select another switch from the switch module of the preset switch as a new preset switch after determining that the use of the current preset switch meets the preset conditions; the preset conditions include a preset usage time or a preset number of uses, and the switch module includes multiple switches individually connected to the controller.

[0167] In another possible implementation, the controller is further configured to send switch disconnection signals to the closed switches simultaneously or sequentially to control the switches to be disconnected, and the connection lines connecting the switches to the controller correspond one to one to the switches.

[0168] The controller is further configured to send a switch disconnection signal to the switch group included in the inverter to control the switches included in the switch group to disconnect.

[0169] The above are some specific implementations of an inverter and its method and device provided in the embodiments of the present application. Based on this, the present application also provides a corresponding photovoltaic system. The following introduces an inverter provided in the embodiments of the present application.

[0170] A photovoltaic system includes a solar panel string and an inverter, wherein the solar panel string is connected to an input terminal of the inverter and is configured to provide direct current to the inverter;

[0171] The output end of the inverter is connected to the power grid and is configured to convert the DC power of the DC power supply into AC power and transmit the AC power to the power grid. The inverter adopts one of the above-mentioned inverters.

[0172] The embodiments of the present application also provide corresponding devices and computer storage media for implementing the solutions provided by the embodiments of the present application.

[0173] The device includes a memory and a controller, the memory is used to store instructions or codes, and the controller is used to execute the instructions or codes so that the device executes an inverter abnormal shutdown method of any embodiment of the present application.

[0174] The computer storage medium stores code. When the code is executed, the device executing the code implements an abnormal shutdown method for an inverter according to any embodiment of the present application.

[0175] The "first" and "second" in the names such as "first" and "second" (if any) mentioned in the embodiments of this application are only used as name identifiers and do not represent the first or second in order.

[0176] Through the description of the above embodiments, it can be known that those skilled in the art can clearly understand that all or part of the steps in the above-mentioned embodiment methods can be implemented by means of software plus a general hardware platform. Based on this understanding, the technical solution of the present application can be embodied in the form of a software product, which can be stored in a storage medium, such as a read-only memory (ROM) / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network communication device such as a router) to execute the methods of each embodiment of the present application or certain parts of the embodiments.

[0177] Each embodiment in this specification is described in a progressive manner. The same or similar parts between the embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple. For the relevant parts, refer to the partial description of the method embodiment. Some or all of the modules can be selected according to actual needs to achieve the purpose of the embodiment. Those of ordinary skill in the art can understand and implement it without paying any creative work.

[0178] The above are merely exemplary embodiments of the present application and are not intended to limit the scope of protection of the present application.

Claims

1. An inverter, comprising: An inverter circuit, a switch module and a controller, wherein the switch module connects a plurality of switches in series, the input end of the inverter circuit is connected to a DC source, the output end of the inverter circuit is connected to a power grid through the switch module, and the control end of at least one of the plurality of switches is independently connected to the controller; The inverter circuit is used to convert the direct current output by the direct current source into alternating current; The switch module is used to transmit the AC power outputted by the output end of the inverter circuit to the power grid when it is turned on, and to stop transmitting the AC power outputted by the output end of the inverter circuit when it is turned off; The controller is used to shut down the inverter drive and disconnect at least one switch in the switch module that is independently connected to the controller when confirming that the inverter is short-circuited.

2. The inverter according to claim 1, wherein the inverter circuit is a multi-phase inverter circuit, and each phase output end of the multi-phase inverter circuit is connected to a switch module; The control end of each switch in each switch module is independently connected to the controller; or, The control ends of the first switches in each switch module are independently connected to the controller, and the control ends of the second switches in the same switch group are commonly connected to the controller, and the second switches in the same switch group correspond one-to-one to the switch modules included in the inverter; wherein, The first switch in each switch module is a part of the switches included in the switch module, and the second switch is a switch other than the first switch among the switches included in the switch module.

3. According to the inverter of claim 2, the control end of each switch in each switch module is independently connected to the controller, and each control end of the switch corresponds to a connecting line connected to the controller, and the connecting line is used to transmit the switch opening signal or the switch closing signal sent by the controller.

4. The inverter according to claim 3, the controller is further used to control a switch in a switch module corresponding to each phase electricity in the inverter circuit to be opened according to the current at the output end of each phase electricity in the inverter circuit; and simultaneously or sequentially send a switch opening signal to the closed switches in all the switch modules connected to the inverter circuit to control the closed switches in the switch modules connected to the inverter circuit to be opened.

5. According to the inverter of claim 2, the control end of the first switch in each switch module is independently connected to the controller, and the control ends of the second switches in the same switch group are commonly connected to the controller, then the control end of each first switch corresponds to a connecting line connected to the controller, and the control end of the second switch in the same switch group is connected to the controller through the same connecting line, and the connecting line is used to transmit the switch opening signal or the switch closing signal sent by the controller.

6. The inverter according to claim 5, each of the switch modules has a first switch; The controller is also used to control a first switch in a switch module corresponding to each phase electricity in the inverter circuit to be disconnected according to the current at the output end of each phase electricity in the inverter circuit, and then send a switch disconnection signal to the switch group included in the inverter to control the second switch included in the switch group to be disconnected.

7. The inverter according to claim 5, wherein each switch module has at least two first switches; The controller is also used to control a first switch in a switch module corresponding to the phase electricity to be disconnected according to the current at the output end of each phase electricity in the inverter circuit, and then send a switch disconnection signal to the switch group and the closed first switch included in the inverter to control the second switch included in the switch group and the closed first switch to be disconnected.

8. According to the inverter according to any one of claims 1-4, 5, and 7, the controller is further used to select a switch that can be used as a preset switch other than the preset switch from the switch module corresponding to the preset switch as a new preset switch after determining that the use of the current preset switch meets the preset condition; the preset condition includes a preset usage time or a preset number of uses, the preset switch is a switch pre-set in the controller for controlling the shutdown of the switch module, and the preset switch is a switch separately configured with a connecting line connected to the controller.

9. The inverter according to any one of claims 1 to 8, wherein the inverter short circuit comprises a short circuit of the inverter photovoltaic panel cable to the ground, and a short circuit of the busbar positive and negative electrodes to the ground; The controller is further used to confirm that the photovoltaic panel cable is short-circuited to the ground when the first abnormal condition that the photovoltaic panel cable of the inverter is short-circuited to the ground is met; and to confirm that the positive and negative poles of the busbar are short-circuited to the ground when the second abnormal condition that the positive and negative poles of the busbar are short-circuited to the ground is met; The first abnormal condition includes that at the same time, the absolute value of the vector sum of the current values ​​collected from the output ends of the N phases of the N-phase inverter is greater than the first threshold, N is greater than 1, and the first threshold is the maximum value of the absolute value of the vector sum of the current collection values ​​of the N phase circuits at the same time when the power converter is normal; or, the current collection values ​​of the output ends of the N phases of the N-phase alternating current are all positive, N is greater than 1; or, the current collection values ​​of the output ends of any two phases of the N phases of the N-phase alternating current are all positive, N is greater than 2; or, the current collection value of the output end of at least one phase of the N phases exceeds a preset value, and the voltage collection value of the output end of the phase corresponding to the current collection value is positive, and the preset value is the current collection value of the output end of the phase when the power converter is operating normally; the current collection value is the average value or the maximum value determined after multiple collections of the phase circuit according to the switching frequency of the first switch, and the multiple collections include collecting the instantaneous effective value of the current or collecting the instantaneous peak value of the current; The second abnormal condition includes that the voltage drop slope of the bus is greater than the voltage drop slope when the bus operates normally, and the minimum value of the bus voltage is less than the inverter operating voltage.

10. An abnormal shutdown method for an inverter, applied to a controller in an inverter according to any one of claims 1 to 9, the method comprising: When determining that the inverter is short-circuited, shutting down the inverter drive of the inverter; Continuously collecting electrical parameters of the output end of each phase of the inverter circuit, wherein the electrical parameters are one or more of voltage values ​​or current values; Determine the zero-crossing moment of the current value of each phase according to the collected electrical parameters of each phase; According to the zero-crossing moment, a preset switch in the switch module corresponding to the phase power is disconnected, wherein the preset switch is a switch pre-set in the controller for controlling the switch module to be turned off, and the preset switch is a switch whose control end is independently connected to the controller.

11. The method according to claim 10, wherein the inverter short circuit is a short circuit of the inverter photovoltaic panel cable to the ground; The step of determining the zero-crossing moment of the current value of each phase electricity according to the collected electrical appliance parameters includes: Determine the time when the voltage value collected at the output end of the phase electricity changes from a negative value to a positive value for the first time as the first zero-crossing time of the current value of the phase electricity; or, In the case where the current value collected at the output end of the phase electricity shows a downward trend over time, the second zero-crossing moment of the current value of the phase electricity is determined according to the slope of the downward trend, and the signal moment is obtained by subtracting the switch power-off delay time from the second zero-crossing moment; The method of disconnecting a preset switch in a switch module corresponding to the phase power according to the zero-crossing time includes: Within a preset time length starting from the zero-crossing moment or the signal moment, the switch mode corresponding to the phase current is The preset switch in the group sends a switch-off signal to disconnect the preset switch, and the preset time length is the time length between the moment when the voltage value collected at the output end of the phase electricity changes from a negative value to a positive value for the first time and the moment when the voltage value collected at the output end of the phase electricity changes from the positive value to a negative value for the first time.

12. The method according to claim 10, wherein the inverter short circuit is a short circuit between the positive and negative electrodes of the busbar and the ground; The step of determining the zero-crossing moment of the current value of each phase electricity according to the collected electrical appliance parameters includes: In the case where the current value collected at the output end of the phase electricity shows a downward trend over time, determining the zero-crossing moment of the current value of the phase electricity according to the slope of the downward trend; The method of disconnecting a preset switch in a switch module corresponding to the phase power according to the zero-crossing time includes: Subtract the switch power-off delay time from the zero-crossing time to obtain the signal time, and determine the target current value corresponding to the signal time according to the slope; When the absolute value of the difference between the collected current value and the target current value is less than the target threshold, a switch-off signal is sent to the preset switch in the switch module corresponding to the phase electricity to disconnect the preset switch. The target threshold is the difference between two adjacent collected current values.

13. An inverter abnormal shutdown device, applied to a controller in an inverter according to any one of claims 1 to 9, the device comprising: a processing unit configured to shut down an inverter drive of the inverter when determining that the inverter is short-circuited; A collection unit is configured to continuously collect electrical parameters of the output end of each phase of the inverter circuit, wherein the electrical parameters are one or more of voltage values ​​or current values; A calculation unit is configured to determine the slope of the downward trend and the zero-crossing time of the electrical parameter when the electrical parameter collected at the output end of each phase of electricity shows a downward trend; A control unit is configured to disconnect a preset switch in the switch module corresponding to the phase electricity according to the zero-crossing moment, wherein the preset switch is pre-set in the controller and is configured to control the switch module to shut down, and the preset switch is a switch whose control end is independently connected to the controller.

14. A photovoltaic system, comprising a solar panel string and an inverter, wherein the solar panel string is connected to an input terminal of the inverter to provide direct current to the inverter; The inverter output end is connected to the power grid, and is used to convert the DC power of the DC power supply into AC power and transmit it to the power grid. The inverter adopts an inverter as described in any one of claims 1-9.

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