Method for operating a photovoltaic system

Abstract

A photovoltaic system comprises an inverter adapted to convert DC power supplied by a photovoltaic module of a photovoltaic power plant via a power cable to the inverter into an AC current for an AC power grid, wherein the inverter has a base station connected to a module level device by the power cable, which is provided for monitoring and / or controlling the associated photovoltaic module of the photovoltaic power plant, wherein, if the inverter does not receive sufficient energy from the photovoltaic power plant and the AC power grid, a controller is adapted to activate a deadlock prevention mode of an energy supply unit connected to the inverter, wherein the inverter receives energy from the energy supply unit so that the base station of the inverter can continue to send an operation permission, PTO, signal to the module level device of the photovoltaic power plant via the power cable.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic technology. Background Technology

[0002] US 2016 / 329721 A1 describes an apparatus for controlling electricity output from a renewable energy source to a public power grid. The apparatus includes means for monitoring the direction of electricity flow within the renewable energy source and means for isolating the electricity flow from the renewable energy source to the main power source. When a reverse electricity flow is sensed between the renewable energy source and the main power source, the monitoring means signals the isolation means to restrict the renewable energy source to the main power source.

[0003] A photovoltaic (PV) system may include one or more PV strings or PV modules within a PV array. A PV array with one or more PV strings forms a PV generator and can be connected to an inverter of the PV system via a DC line. The inverter is adapted to convert DC current received from the PV generator into AC current and supply that AC current to the AC power grid.

[0004] For photovoltaic (PV) systems, power line communication (PLCs) can be used to transmit data over existing power cables. PLCs are used to transmit keep-alive signals to control the rapid shutdown (RSD) of the PV array at the PV module level. For example, some standards and regulations require that keep-alive signals be sent continuously from the inverter to one or more module-level devices of the PV generator.

[0005] The inverter in a photovoltaic (PV) system sends a keep-alive signal, specifically a Pre-Operation Execution (PTO) signal, to the module-level unit (MLD) of the PV generator. The inverter includes a base station with a transmitter capable of sending the keep-alive signal to the MLD. The base station can draw power from the PV generator, the AC power grid, and / or a local energy supply unit to send the keep-alive signal to the MLD.

[0006] However, if the inverter receives no energy from the AC power grid, the photovoltaic (PV) generator, and the energy supply unit, it can no longer send a keep-alive signal to the PV generator's module-level device (MLD). This causes the PV generator's MLD to shut down. If, under these circumstances, sufficient energy subsequently becomes available at the PV generator to turn on the MLD, the inverter will not be able to send the necessary keep-alive signal. This is because the inverter may no longer be able to receive energy from the PV generator, as both the AC power grid and the energy supply unit are disconnected. This creates an undesirable deadlock situation, where the PV system's inverter cannot send the required keep-alive signal even when sufficient energy is available at the PV generator. Summary of the Invention

[0007] Therefore, the object of the present invention is to provide a photovoltaic system that avoids this deadlock situation and ensures the continuous operation of the photovoltaic system.

[0008] This objective is achieved by a photovoltaic system including the features of the independent claim and a method for operating the photovoltaic system. Other advantageous embodiments are the subject of the dependent claims.

[0009] According to a first aspect of the present invention, a photovoltaic system is provided, the photovoltaic system including an inverter adapted to convert DC power supplied to the inverter by photovoltaic modules of a photovoltaic generator via power cables into AC current for use in an AC power grid.

[0010] The inverter includes a base station connected to a module-level device via the power cable. This module-level device is configured to monitor and / or control the associated photovoltaic modules of the photovoltaic generator.

[0011] If the inverter does not receive sufficient energy from the photovoltaic generator and the AC power grid, the controller of the photovoltaic system is adapted to activate a deadlock prevention mode for the energy supply unit connected to the inverter, wherein the inverter receives energy from the energy supply unit, enabling the inverter's base station to continue sending operation permission (PTO) signals to the module-level device of the photovoltaic generator via the power cable.

[0012] In a photovoltaic system according to a first aspect of the invention, a specific deadlock prevention mode is provided to control the state of charge of the energy supply unit, such that during a possible deadlock, the inverter of the photovoltaic system always has sufficient energy to send a keep-alive signal to the module-level device.

[0013] The energy supply unit of the photovoltaic system can be switched to different operating modes by the controller.

[0014] In a possible embodiment of the photovoltaic system according to the first aspect of the invention, the controller is integrated into the inverter.

[0015] In a possible implementation of the photovoltaic system, the first operating mode of the energy supply unit includes a normal operating mode in which the energy supply unit is configured to: supply energy to the load network of the photovoltaic system and receive energy from the photovoltaic generator and / or the AC power grid, so as to maintain the state of charge (SoC) of the energy supply unit above a first SoC level L1.

[0016] In another possible embodiment of the photovoltaic system according to the first aspect of the invention, the energy supply unit includes a standby operating mode as another operating mode, in which the energy supply unit is configured to supply energy to the load network via the inverter when the state of charge (SoC) of the energy supply unit is lower than a first SoC level L1. In the standby operating mode, the energy supply unit is configured to supply energy to the load network of the photovoltaic system 1 when the AC power grid is disconnected, until the SoC of the energy supply unit reaches a second SoC level L2.

[0017] In another possible embodiment of the photovoltaic system according to the first aspect of the invention, as another operating mode, the energy supply unit includes a deadlock prevention mode in which the energy supply unit is configured to supply energy only to the inverter when the state of charge (SoC) of the energy supply unit is lower than the second SoC level L2 and no energy is obtained from the AC power grid.

[0018] In another possible embodiment of the photovoltaic system according to the first aspect of the present invention, as another operating mode, the energy supply unit includes a standby operating mode in which the energy supply unit ceases to supply energy to the inverter when the state of charge (SoC) of the energy supply unit is lower than a predetermined third minimum SoC level L3 and no energy is obtained from the AC power grid.

[0019] In a possible embodiment of the photovoltaic system according to the first aspect of the invention, the energy supply unit of the photovoltaic system is configured to supply energy only to the inverter if the inverter does not receive energy from the photovoltaic generator and the AC power grid within a predetermined time period.

[0020] In a possible implementation, this time period can be configured and stored in the controller's register.

[0021] In this embodiment, the time period can be adjusted according to the usage of the photovoltaic system. This provides greater flexibility for the photovoltaic system according to the first aspect of the invention.

[0022] In another possible embodiment of the photovoltaic system according to the first aspect of the invention, the energy supply unit of the photovoltaic system is configured to supply energy only to the inverter of the photovoltaic system if the inverter does not receive a predetermined amount of energy from the photovoltaic generator and the AC power grid.

[0023] In a possible implementation, a predetermined amount of energy may also be stored in the associated configuration register of the controller. Therefore, also in this implementation, the amount of energy can be adapted to the specific usage scenario.

[0024] In another possible embodiment of the photovoltaic system according to the first aspect of the invention, in the standby operation mode of the energy supply unit, energy from the energy supply unit is no longer supplied to the inverter of the photovoltaic system, and the inverter automatically shuts down.

[0025] In another possible embodiment of the photovoltaic system according to the first aspect of the invention, when the state of charge (SoC) of the energy supply unit reaches a predetermined level higher than each predetermined SoC level L1, L2, or L3, the controller automatically triggers an SoC warning signal. The predetermined level is the SoC level of the energy supply unit.

[0026] In a possible implementation, the predetermined level is the same percentage of the SoC above each SoC level L1, L2, and L3.

[0027] In a possible implementation, the predetermined levels corresponding to each SoC level L1, L2, and L3 are different.

[0028] In a possible implementation, the predetermined level of each SoC level L1, L2 and L3 is equal to the corresponding SoC level L1, L2 and L3.

[0029] The predetermined SoC levels of each SoC level L1, L2, L3 of the energy supply unit used to issue warning signals are stored in the corresponding configuration register of the controller.

[0030] For example, since a warning signal for SoC level L3 is provided at a predetermined level above L3, this allows for emergency measures to be taken to avoid shutting down the inverter.

[0031] In another possible embodiment of the photovoltaic system according to the first aspect of the invention, the controller includes a first interface for receiving information about the current operating mode of the energy supply unit and about operating parameters, the operating parameters including the state of charge (SoC) of the energy supply unit and / or the switching state of the energy supply unit switch, the energy supply unit switch being configured to connect the energy supply unit to the inverter.

[0032] In another possible embodiment of the photovoltaic system according to the first aspect of the invention, the controller includes a second interface for receiving information about the current state of the AC power grid, the current state including the switching state of a grid switch configured to connect the AC output of the inverter to the AC power grid.

[0033] In another possible embodiment of the photovoltaic system according to the first aspect of the present invention, the SoC levels L1, L2, and L3 of the energy supply unit for controlling the operating mode of the energy supply unit are stored in the corresponding configuration registers of the controller.

[0034] In another possible embodiment of the photovoltaic system according to the first aspect of the invention, the first SoC level L1 and the second SoC level L2 can be adjusted through the user interface of the level photovoltaic system.

[0035] In another possible embodiment of the photovoltaic system according to the first aspect of the invention, the third SoC level L3 is predefined according to the specifications of the power supply unit manufacturer.

[0036] In another possible embodiment of the photovoltaic system according to the first aspect of the invention, the second SoC level L2 is adjusted to cover the standby energy consumption of the inverter including its base station for a predetermined period of time to prevent the state of charge (SoC) of the energy supply unit from dropping to a predetermined minimum third SoC level L3.

[0037] In a possible embodiment of the photovoltaic system according to the first aspect of the invention, the energy supply unit is connected to the inverter via an energy supply unit switch, wherein the energy supply unit switch is an integral part of the energy supply unit.

[0038] In a possible embodiment of the photovoltaic system according to the first aspect of the invention, the energy supply unit is connected to the inverter via an energy supply unit switch, wherein the energy supply unit switch is external to the energy supply unit.

[0039] According to a second aspect, the present invention provides a method for operating a photovoltaic system, the photovoltaic system including an inverter that converts DC power supplied to the inverter from photovoltaic modules of a photovoltaic generator via power cables into AC current supplied to an AC power grid, wherein the inverter has a base station connected via power cables to a module-level device of the photovoltaic generator, the module-level device monitoring and / or controlling associated photovoltaic modules of the photovoltaic generator, wherein if the inverter does not receive sufficient energy from the photovoltaic generator and the AC power grid, a controller activates a deadlock prevention mode of an energy supply unit connected to the inverter, wherein the inverter receives energy from the energy supply unit such that the base station of the inverter can continue to send an operation permission signal to the module-level device of the photovoltaic generator via the power cables.

[0040] In a possible implementation of the method according to the second aspect of the invention, if the inverter does not receive energy from the photovoltaic generator and the AC power grid within a predetermined time period, the energy supply unit supplies energy only to the inverter in the deadlock prevention mode of the energy supply unit.

[0041] In another possible implementation of the method according to the second aspect of the invention, if the inverter does not receive a predetermined amount of energy from the photovoltaic generator and the AC power grid, the energy supply unit supplies energy only to the inverter in the deadlock prevention mode of the energy supply unit.

[0042] In another possible implementation of the method according to the second aspect of the invention, when the state of charge (SoC) of the energy supply unit drops to a predetermined level corresponding to each SoC level L1, L2 and L3, an SoC warning signal is automatically triggered by the controller. Attached Figure Description

[0043] Possible embodiments of different aspects of the invention will now be described in more detail with reference to the accompanying drawings.

[0044] Figure 1 A block diagram illustrating possible exemplary embodiments of a photovoltaic system according to a first aspect of the present invention is shown;

[0045] Figure 2 Another block diagram is shown to illustrate a possible exemplary embodiment of a photovoltaic system according to the first aspect of the present invention;

[0046] Figure 3 A state diagram illustrating the operation of a possible embodiment of a photovoltaic system according to the first aspect of the present invention is shown.

[0047] Figure 4A diagram is shown illustrating different SoC levels L of an energy supply unit for controlling the operation of a photovoltaic system according to a first aspect of the present invention. Detailed Implementation

[0048] Figure 1 A block diagram schematically illustrates a possible exemplary embodiment of a photovoltaic system 1 according to a first aspect of the present invention. In the illustrated exemplary embodiment, a photovoltaic generator 2 is connected to an inverter 3 of the photovoltaic system 1. The inverter 3 is adapted to convert the DC power received from the photovoltaic modules 8-1, 8-2, 8-3 of the photovoltaic generator 2, supplied to the inverter 3 via power cables 9, into AC current for the AC power grid 5.

[0049] Inverter 3 includes a DC input side and an AC output side. In the illustrated embodiment, the AC output of inverter 3 is connected to the AC power grid 5 via a grid switch 4. In the illustrated embodiment, inverter 3 includes a base station 6, which is connected to module-level devices 7-1, 7-2, and 7-3 via power cables 9. Module-level devices 7-1, 7-2, and 7-3 are configured to monitor and / or control the associated photovoltaic modules 8-1, 8-2, and 8-3 of photovoltaic generator 2.

[0050] In a preferred embodiment, photovoltaic modules 8-1, 8-2, 8-3, and 8-4 are connected via, as shown in the following... Figure 2 In the embodiment shown, the power cable 9 in the loop is connected to the base station 6 of the inverter 3. The base station 6 includes a transmitter adapted to continuously send operation authorization (PTO) signals via the power cable 9 to receivers integrated in the module-level devices 7-1, 7-2, 7-3, and 7-4 of the photovoltaic generator 2.

[0051] like Figure 1 As shown, inverter 3 is connected to the energy supply unit 10 of photovoltaic system 1 at its DC input side. In a possible implementation, energy supply unit 10 is connected to inverter 3 via energy supply unit switch 11, as shown below. Figure 1 As shown.

[0052] In the illustrated embodiment, the photovoltaic system 1 includes a controller 12, which can be connected to the inverter 3 via an interface. In an alternative embodiment, the controller 12 may also be integrated into the inverter 3. If the inverter 3 does not receive sufficient energy from the photovoltaic generator 2 and the AC power grid 5, the controller 12 of the photovoltaic system 1 is adapted to activate a deadlock prevention mode of the energy supply unit 10 connected to the inverter 3.

[0053] In deadlock prevention mode, inverter 3 receives energy from energy supply unit 10, enabling the transmitter of base station 6 of inverter 3 to continue sending operation permission signals (i.e., keep-alive signals) to module-level devices 7-1, 7-2, 7-3, and 7-4 of photovoltaic generator 2 via power cable 9. Energy supply unit 10 of photovoltaic system 1 can be used to supply energy to local load network 13 via inverter 3.

[0054] The controller 12 of the photovoltaic system 1 includes an interface adapted to receive information about the current operating mode of the energy supply unit 10. The controller 12 can also obtain information about the operating parameters of the energy supply unit 10 via this interface, including the state of charge (SoC) of the energy supply unit 10.

[0055] like Figure 1 As shown, the energy supply unit 10 includes an energy supply unit switch 11, which disconnects the energy supply unit 10 from the inverter in the event of a fault (e.g., when communication between the inverter 3 and / or its controller 12 and the energy supply unit 10 is interrupted). The controller 12 can also monitor the switching state of the energy supply unit switch 11 to connect or disconnect the energy supply unit 10 from the DC input side of the inverter 3.

[0056] The controller 12 may further include a second interface for receiving information about the current state of the AC power grid 5, including the on / off state of the grid switch 4. In the event of a fault, the grid switch 4 can be used to disconnect the photovoltaic system 1 from the power grid 5. In a possible implementation, the grid switch 4 may be controlled by the local controller 12 of the photovoltaic system 1. In an alternative implementation, the grid switch 4 may be controlled by a remote controller of the operator of the AC power grid 5. In the event of a fault in the AC power grid 5, the grid switch 4 can be switched to disconnect the inverter 3 from the AC power grid 5, thereby allowing energy to be supplied to the load in standby power mode. Figure 1 In the embodiment shown, the photovoltaic generator 2 is equipped with a module to activate the entity.

[0057] The transmitter at base station 6 of inverter 3 continuously sends Operation Authorization (PTO) signals to different module-level devices 7-1, 7-2, 7-3, and 7-4 of photovoltaic generator 2. As long as the receivers integrated in module-level devices 7-1, 7-2, 7-3, and 7-4 receive the PTO signal from the transmitter at base station 6 of inverter 3 via power cable 9, the associated photovoltaic modules 8-1, 8-2, 8-3, and 8-4 will not be deactivated. Therefore, interruption of the continuous transmission of the PTO signal due to insufficient energy at base station 6 of inverter 3 is avoided, thus preventing an undesirable deadlock situation.

[0058] During the day, the photovoltaic generator 2 provides sufficient energy, which can also be used by the base station 6 of the inverter 3 to generate and provide a power operation authorization (PTO) signal. However, at night, the photovoltaic generator 2 does not generate photovoltaic energy. Therefore, when the AC power grid 5 is disconnected from the inverter 3 due to the grid switch 4, and when the photovoltaic generator 2 does not generate energy, the power supply of the inverter 3 and its integrated components (such as the base station 6) depends on the local energy supply unit 10 of the photovoltaic system 1.

[0059] If the photovoltaic generator 2 cannot provide sufficient energy due to unavailability or low levels of solar radiation, the module-level devices 7-1, 7-2, 7-3, 7-4 and the integrated receiver may not be able to receive enough energy. In this case, if the energy supply unit 10 reaches its minimum state of charge (SoC), it may not be able to provide sufficient energy, and the controller 12 of the inverter 3 will switch it to standby mode. Furthermore, the energy supply unit switch 11 will be opened to disconnect the energy supply unit 10 from the inverter 3.

[0060] In this situation, in the conventional photovoltaic system 1, although sufficient energy can be obtained again at the photovoltaic modules 8-1, 8-2, 8-3, and 8-4 of the photovoltaic generator 2 to activate the module-level devices 7-1, 7-2, 7-3, and 7-4, the inverter 3 and its integrated base station 6 cannot send power line communication PLC control signals because the energy supply unit 10 and the AC power grid 5 are disconnected.

[0061] In such Figure 1 In the photovoltaic system 1 shown in the embodiment, the energy supply unit 10 can be switched between four different operating modes by the controller 12. The energy supply unit 10 includes a normal operating mode, a standby operating mode, a deadlock prevention mode, and a standby operating mode, as well as... Figure 3 The state diagram is shown below. Figure 4 It shows Figure 1 The photovoltaic system 1 shown illustrates different states of charge (SoC) levels (L1, L2, and L3) of the energy supply unit 10. Any number of operating modes can be defined, and the invention is not limited to any particular set of operating modes.

[0062] In normal operating mode (mode 0), the energy supply unit 10 is configured to supply energy to the load network 13 of the photovoltaic system 1 and receive energy from the photovoltaic generator 2 and / or the AC power grid 5 to maintain its state of charge (SoC) above the first SoC level L1.

[0063] In the standby operation mode (mode 1), when the state of charge (SoC) of the energy supply unit 10 is lower than the first SoC level L1, the energy supply unit 10 is configured to supply energy to the load network 13 via the inverter 3.

[0064] In the deadlock prevention mode (mode 2) of the energy supply unit 10, the energy supply unit 10 is configured to supply energy to the inverter 3 only when the state of charge (SoC) of the energy supply unit 10 is lower than the second SoC level L2 and no energy is obtained from the AC power grid 5.

[0065] In the standby operation mode (mode 3) of the energy supply unit 10, when the state of charge (SoC) of the energy supply unit 10 drops below the predetermined third minimum SoC level L3 and no energy is obtained from the AC power grid 5, energy from the energy supply unit 10 is no longer supplied to the inverter 3.

[0066] When the AC power grid 5 is disconnected from the inverter 3, the controller 12 switches the energy supply unit 10 from the normal operation mode to the standby operation mode.

[0067] When the energy supply unit 10 is charged from the photovoltaic generator 2 or the AC power grid 5 to a level higher than the SoC level L1 (e.g.) Figure 4 As shown, controller 12 switches energy supply unit 10 from standby operation mode to normal operation mode. In other words, when the AC power grid 5 is reconnected to inverter 3, controller 12 switches energy supply unit 10 from standby operation mode to normal operation mode.

[0068] When the state of charge (SoC) of the energy supply unit 10 drops below the second SoC level L2 and no energy is obtained from the AC power grid 5, the controller 12 switches the energy supply unit 10 from the standby operation mode to the deadlock prevention mode, wherein the energy supply unit 10 is configured to supply power only to the inverter 3.

[0069] When the energy supply unit 10 is charged to SoC level L1 by the photovoltaic generator 2, the controller 12 switches the energy supply unit 10 from deadlock prevention mode to standby operation mode. In this case, since the AC power grid 5 is unavailable, it cannot be used to charge the energy supply unit 10.

[0070] If the power supply unit 10 is further discharged to the SoC level L3, the controller 12 switches the power supply unit 10 from the deadlock prevention mode to the standby operation mode. In this case, neither the AC power grid 5 nor the photovoltaic generator 2 can be used to supply energy to the power supply unit 10, so the power supply unit 10 is discharged to the SoC level L3.

[0071] With the AC power grid becoming available again, grid 5 will supply energy to inverter 3. Inverter 3 then sends an Operation Authorization (PTO) signal to the module-level device (MLD) of the photovoltaic generator. This results in the reconnection of photovoltaic generator 2 to inverter 3. Photovoltaic generator 2 will now also be able to supply energy to inverter 3, thereby charging energy supply unit 10. Once the battery's SoC level is higher than SoC level L1, controller 12 switches energy supply unit 10 from standby protection mode to normal operation mode.

[0072] When the AC power grid 5 is available and the power supply unit 10 discharges to the SoC level L3, the controller 12 switches the power supply unit 10 from the normal protection mode to the standby operation mode.

[0073] Figure 4 It shows Figure 1 The photovoltaic system 1 is shown with different states of charge (SoC) levels for its energy supply unit 10. At SoC 100%, the energy supply unit 10 is fully loaded. As long as the SoC of the energy supply unit 10 is above the first SoC level L1, it operates in a normal operating mode (mode 0), where the inverter 3 receives energy from the photovoltaic generator 2 and / or from the AC power grid 5, and where the energy supply unit 10 can be used to supply energy to the local load network 13. The energy supply unit 10 receives energy from the photovoltaic generator 2 and / or from the power grid 5 to maintain its SoC above the first SoC level L1. Hysteresis can be provided when the power grid 5 is connected.

[0074] When the AC power grid 5 is disconnected from the inverter 3, the energy supply unit 10 operates in standby mode (mode 1). During standby mode, the energy supply unit 10 supplies a predetermined amount of energy to the local load network 13. Energy supply unit 10 is still allowed to transfer energy to the local load network 13 during standby mode. The energy supply unit 10 transfers energy until its state of charge (SoC) reaches SoC L2.

[0075] In standby operation mode, as long as the state of charge of energy supply unit 10 does not reach the second SoC level L2, energy supply unit 10 is configured to supply energy to the local load network 13 of photovoltaic system 1 and inverter 3. In standby operation mode, inverter 3 receives energy from photovoltaic generator 2 and / or from energy supply unit 10. SoC level L1 provides backup capacity for standby mode. SoC level L2 provides backup capacity during standby mode to prevent PLC deadlock. SoC level 2 represents the capacity of energy supply unit 10, which needs to reserve energy to supply inverter 3 until photovoltaic generator 2 recovers sufficient energy to resume supplying energy to inverter 3.

[0076] In deadlock prevention mode (mode 2), inverter 3 receives energy only from energy supply unit 10, especially when power grid 5 and photovoltaic generator 2 are disconnected from inverter 3 through grid switch 4 and energy supply unit switch 11.

[0077] In deadlock prevention mode, as long as the state of charge (SoC) of the energy supply unit 10 is between the first SoC level L1 and the second SoC level L2, the inverter 3 and its integrated components (specifically the base station 6) can draw energy from the energy supply unit 10. The inverter 3 draws energy from the energy supply unit 10 until the photovoltaic generator 2 recovers sufficient energy and begins supplying the generated energy to the inverter 3. For example, at night, the inverter 3 does not receive energy from the photovoltaic generator 2, and if the AC power grid 5 is disconnected, the energy supply unit 10 operates in deadlock prevention mode 2. In this case, the energy supply unit 10 is not allowed to transfer energy to the local load network 13.

[0078] In deadlock prevention mode 2, if inverter 3 does not receive energy from photovoltaic generator 2 and photovoltaic grid 5 within a predetermined time period, energy supply unit 10 supplies energy between SoC level L2 and SoC level L3 to inverter 3. Energy supply unit 10 of photovoltaic system 1 is configured to supply energy only to inverter 3 in deadlock prevention mode 2 between SoC level L2 and SoC level L3 if inverter 3 receives neither energy from photovoltaic generator 2 nor from AC power grid 5 within the predetermined time period. In a possible implementation, the predetermined time period may be stored in a register of controller 12. In a possible implementation, the predetermined time period may be adjusted, for example, via a user interface or control interface of controller 12 to adapt to specific usage conditions.

[0079] In an alternative implementation, the energy supply unit 10 of system 1 can be configured to supply energy only to the inverter 3 in deadlock prevention mode 2 if the inverter 3 does not receive a predetermined amount of energy from the photovoltaic generator 2 or the AC power grid 5. In a possible implementation, the predetermined amount of energy can also be specified in a register accessible to the controller 12 of the photovoltaic system 1.

[0080] If the state of charge (SoC) drops further, it may reach a predetermined minimum third SoC level L3, which can be specified by the power supply unit manufacturer. When the SoC of the power supply unit 10 is below the minimum predetermined third SoC level L3 and no energy is obtained from the AC power grid 5, the controller 12 switches the power supply unit 10 to standby operation mode (mode 3). The SoC level L3 is the minimum state of charge (SoC) defined by the power supply unit manufacturer.

[0081] The SoC levels L1, L2, and L3 of the energy supply unit 10, used to control the operating mode of the energy supply unit 10, can be stored in the configuration register of the controller 12 in a possible implementation. In a possible implementation, the first SoC level L1 and the second SoC level L2 can be adjusted through the user interface of the photovoltaic system 1. The SoC level L3 is predefined according to the specifications of the energy supply unit manufacturer.

[0082] The SoC level L2 is calculated by considering the inverter's own consumption, the energy supply unit's own consumption, the deadlock prevention time, and the maximum capacity of the energy supply unit 10. The inverter's own consumption defines the energy consumption of the inverter 3 as functional. The energy supply unit's own consumption defines the energy consumption of the energy supply unit 10 as functional. The formula used to calculate the SoC level L2 is given below (Equation 1). The deadlock prevention time is based on an estimated unavailable or low level of solar irradiance. The estimated unavailable or low level of solar irradiance is based on the actual time and location of system 1.

[0083] SOC level L2 = SoC level L3 + ((Inverter self-consumption + Energy supply unit self-consumption) x Deadlock prevention time) / Maximum capacity of energy supply unit) x 100 --- Equation 1

[0084] In a preferred embodiment, the second SoC level L2 is adjusted to cover the standby energy consumption of the inverter 3, including the base station 6, for a predetermined period of time, so as to prevent the state of charge (SoC) of the energy supply unit 10 from reaching a predetermined minimum third SoC level threshold L3. In the standby operation mode 3 of the energy supply unit 10, the inverter 3 is no longer supplied with energy from the energy supply unit 10, and the inverter 3 is automatically turned off in possible embodiments.

[0085] When the SoC level of the energy supply unit 10 reaches the minimum level SoC L3 and no AC power grid 5 is available, the controller 12 of the inverter 3 can activate the standby operation mode 3, causing the energy supply unit 10 to open its internal relay and the inverter 3 to no longer be powered by the energy supply unit 10 and thus be turned off. Therefore, for safety reasons, the energy supply unit switch 11 is turned on.

[0086] In a possible implementation, when the state of charge (SoC) of the power supply unit 10 reaches a predetermined level higher than each predetermined SoC level L1, L2, or L3, the controller 12 automatically triggers an SoC warning signal. The predetermined level is the SoC level of the power supply unit 10.

[0087] In one possible implementation, the predetermined level is the same percentage of the SoC above each SoC level L1, L2, and L3. In another possible implementation, the predetermined levels corresponding to each SoC level L1, L2, and L3 are different. In yet another possible implementation, the predetermined level for each SoC level L1, L2, and L3 is equal to the corresponding SoC level L1, L2, and L3.

[0088] In a possible implementation, the predetermined SoC level of each SoC level L1, L2, L3 of the energy supply unit 10 used to issue warning signals is stored in the corresponding configuration register of the controller.

[0089] In one example, when the state of charge (SoC) of the power supply unit 10 reaches a predefined minimum third SoC level L3, a SoC warning signal can be triggered by the controller 12. A user-defined SoC warning level can be set to receive notification that a low SoC level L3 has been reached.

[0090] When the state of charge (SoC) of the energy supply unit 10 reaches the minimum SoC level L3 and the AC power grid 5 is available, the controller 12 of the inverter 3 can activate the standby operation mode.

[0091] When the state of charge (SoC) of the power supply unit 10 reaches the absolute minimum defined by the manufacturer (i.e., SoC level L3), and no AC power grid 5 is available, the power supply unit 10 operates in standby mode and discharges itself until it can be recharged from the AC power grid 5 (or, in the worst case, is deeply discharged). When the SoC level L3 is reached and the AC power grid 5 is available, the power supply unit 10 can be recharged from the AC power grid in a hysteretic manner.

[0092] The controller 12 can communicate with the control logic of the energy supply unit 10 via the energy supply unit interface. The controller 12 of the inverter 3 can obtain information about the current operating state of the energy supply unit and its state of charge (SoC), as well as other energy supply unit parameters, from the energy supply unit 10. Furthermore, it can set some states of the energy supply unit (e.g., standby operation mode). The controller 12 of the inverter 3 can implement energy supply unit management, which sets the operating state of the energy supply unit based on the current SoC of the energy supply unit 10 and based on the observed state of the power grid 5 and the configuration of the standby mode.

[0093] Figure 2 Another block diagram illustrating the operation of the photovoltaic system 1 according to the present invention is shown. Figure 2As shown, the base station 6 of inverter 3 is connected to the module-level devices 7-1, 7-2, 7-3, and 7-4 of photovoltaic generator 2 via power cable 9. The module-level devices 7-1, 7-2, 7-3, and 7-4 are configured to monitor and / or control the associated photovoltaic modules 8-1, 8-2, 8-3, and 8-4, as shown. Figure 2 As shown. The number of module-level devices 7-1, 7-2, 7-3, and 7-4 coupled to the DC power network can vary depending on the application.

[0094] exist Figure 2 In the illustrated embodiment, four module-level devices 7-1 to 7-4 are connected to the DC power network or DC loop of the base station 6, which includes the inverter 3. In a possible embodiment, each module-level device may include a module-level monitoring MLM, a transmitter MLM-TX and a fast shutdown RSD, and a receiver RSD-RX. In a possible embodiment, the base station 6 also includes a transmitter and a fast shutdown receiver.

[0095] In a possible implementation, base station 6 is integrated into inverter 3. The transmitter of base station 6 can be adapted to send a fast shutdown RSD control signal to module-level devices 7-1, 7-2, 7-3, and 7-4 via power cable 9 in a predefined time slot in the downlink channel DL-CH. The base station receiver of base station 6 can be adapted to receive monitoring signals generated by module-level devices 7-1, 7-2, 7-3, and 7-4 via power cable 9 in a time slot in the uplink channel UL-CH allocated to module-level devices 7-1, 7-2, 7-3, and 7-4.

[0096] Each module-level device can be adapted to monitor the physical parameters of the associated photovoltaic module. These physical parameters may include the current, voltage, temperature, and / or energy generated by the respective photovoltaic module. These parameters can be communicated to the control unit and / or base station 6 via communication signals. In a possible implementation, the signal amplitude of the communication signal transmitted by the transceiver via the associated duplexer circuit can be automatically adjusted according to the monitored impedance of each photovoltaic generator 2.

[0097] The number of photovoltaic modules integrated into the photovoltaic generator 2 can vary depending on the usage. Figure 3 In the embodiment shown in the state diagram, the power supply unit 10 can operate in four different operating modes under the control of the controller 12. The operating modes may include the associated SoC range of the power supply unit 10.

[0098] exist Figure 1In the illustrated embodiment, controller 12 is located at inverter 3. In another possible embodiment, remote controller 12 can be implemented and connected to photovoltaic system 1 via a data network. Other embodiments are possible. For example, photovoltaic system 1 may include more than one energy supply unit 10 and associated energy supply unit switches 11.

[0099] Figures 1 to 4 The embodiments of the photovoltaic system 1 shown according to the present invention are merely exemplary and are not intended to limit the scope of the invention.

Claims

1. A photovoltaic system (1), comprising: An inverter (3) adapted to convert DC power supplied to the inverter (3) via power cables (9) from photovoltaic modules (8-1, 8-2, 8-3, 8-4) of a photovoltaic generator (2) into AC current for an AC power grid (5). The inverter (3) has a base station (6) which is connected to a module-level device (7-1, 7-2, 7-3, 7-4) via the power cable (9). The module-level device (7-1, 7-2, 7-3, 7-4) is configured to monitor and / or control the associated photovoltaic modules (8-1, 8-2, 8-3, 8-4) of the photovoltaic generator (2). If the inverter (3) does not receive sufficient energy from the photovoltaic generator (2) and the AC power grid (5), the controller (12) is adapted to activate a deadlock prevention mode of the energy supply unit (10) connected to the inverter (3), wherein the inverter (3) receives energy from the energy supply unit (10), enabling the base station (6) of the inverter (3) to continue sending operation permission PTO signals to the module-level devices (7-1, 7-2, 7-3, 7-4) of the photovoltaic generator (2) via the power cable (9). The energy supply unit (10) of the photovoltaic system (1) can be switched to different operating modes by the controller (12), and The energy supply unit (10) is configured to use the state of charge (SoC) level to control the operating mode of the energy supply unit (10), and the state of charge (SoC) level is stored in the configuration register of the controller (12).

2. The photovoltaic system (1) according to claim 1, wherein the different operating modes include: In the normal operating mode, the energy supply unit (10) is configured to supply energy to the load network (13) of the photovoltaic system (1) and receive energy from the photovoltaic generator (2) or from the AC power grid (5) to maintain the state of charge (SoC) of the energy supply unit (10) above the first SoC level L1. In a standby operation mode, the energy supply unit (10) is configured to supply energy to the load network (13) of the photovoltaic system (1) via the inverter (3) until the state of charge (SoC) reaches the second SoC level L2 when the AC power grid (5) is disconnected. Deadlock prevention mode, in which the energy supply unit (10) is configured to: supply energy only to the inverter (3) of the photovoltaic system (1) when the state of charge (SoC) of the energy supply unit (10) is lower than the second SoC level L2 and no energy is obtained from the AC power grid (5), and In the standby operation mode, when the state of charge (SoC) of the energy supply unit drops below a predetermined third SoC level L3 and no energy is obtained from the AC power grid (5), energy from the energy supply unit (10) of the photovoltaic system (1) is no longer supplied to the inverter (3) of the photovoltaic system (1).

3. The photovoltaic system (1) according to claim 1 or 2, wherein, The energy supply unit (10) of the photovoltaic system (1) is configured to supply energy only to the inverter (3) of the photovoltaic system (1) in the deadlock prevention mode of the energy supply unit (10) if the inverter (3) does not receive energy from the photovoltaic generator (2) and the AC power grid (5) within a predetermined time period.

4. The photovoltaic system (1) according to claim 1 or 2, wherein, The energy supply unit (10) of the photovoltaic system (1) is configured to supply energy only to the inverter (3) of the photovoltaic system (1) in the deadlock prevention mode of the energy supply unit (10) if the inverter (3) does not receive a predetermined amount of energy from the photovoltaic generator (2) and the AC power grid (5).

5. The photovoltaic system (1) according to claim 1, wherein, In the standby operation mode of the energy supply unit (10), energy from the energy supply unit (10) is no longer supplied to the inverter (3) of the photovoltaic system (1), and the inverter (3) is automatically shut down.

6. The photovoltaic system (1) according to claim 2, wherein, When the state of charge (SoC) of the energy supply unit (10) reaches a predetermined level higher than each predetermined SoC level L1, L2 or L3, the controller (12) triggers an SoC warning signal.

7. The photovoltaic system (1) according to claim 1, wherein, The controller (12) includes a first interface for receiving information about the current operating mode of the energy supply unit (10) and about operating parameters, the operating parameters including the state of charge (SoC) of the energy supply unit (10) and the switching state of the energy supply unit switch (11), the energy supply unit switch (11) being located between the energy supply unit (10) and the inverter (3).

8. The photovoltaic system (1) according to claim 1, wherein, The controller (12) includes a second interface for receiving information about the current state of the AC power grid (5), the current state including the switching state of the grid switch (4), which is located between the AC power grid (5) and the AC output of the inverter (3).

9. The photovoltaic system (1) according to claim 2, wherein, The first SoC level L1 and the second SoC level L2 are adjustable via a user interface, and the third SoC level L3 is predefined according to the specifications of the power supply unit manufacturer.

10. The photovoltaic system (1) according to claim 2, wherein, The second SoC level L2 is adjusted to cover the standby energy consumption and the energy consumption of the energy supply unit within a predetermined time period, so as to prevent the state of charge SoC of the energy supply unit (10) from dropping below a predetermined third SoC level L3, wherein the standby energy consumption includes the standby energy consumption of the inverter (3) of the base station (6).

11. A method of operating a photovoltaic system (1), the photovoltaic system (1) including an inverter (3) that converts DC power supplied to the inverter (3) via power cables (9) from photovoltaic modules (8-1, 8-2, 8-3, 8-4) of a photovoltaic generator (2) into AC current supplied to an AC power grid (5). in, The base station (6) of the inverter (3) is connected to the module-level devices (7-1, 7-2, 7-3, 7-4) of the photovoltaic generator (2) via the power cable (9). The module-level devices (7-1, 7-2, 7-3, 7-4) monitor and / or control the associated photovoltaic modules (8-1, 8-2, 8-3, 8-4) of the photovoltaic generator (2). If the inverter (3) does not receive sufficient energy from the photovoltaic generator (2) and the AC power grid (5), the controller (12) of the photovoltaic system (1) activates a deadlock prevention mode for the energy supply unit (10) connected to the inverter (3), wherein the inverter (3) receives energy from the energy supply unit (10), enabling the base station (6) of the inverter (3) to continue sending operation permission PTO signals to the module-level devices (7-1, 7-2, 7-3, 7-4) of the photovoltaic generator (2) via the power cable (9). The controller (12) switches the energy supply unit (10) of the photovoltaic system (1) to different operating modes, and The state-of-charge (SoC) level, which is used by the energy supply unit (10) to control the operation mode of the energy supply unit (10), is stored in the configuration register of the controller (12).

12. The method according to claim 11, wherein, If the inverter (3) does not receive energy from the photovoltaic generator (2) and the AC power grid (5) within a predetermined time period, the energy supply unit (10) of the photovoltaic system (1) supplies energy only to the inverter (3) of the photovoltaic system (1) in the deadlock prevention mode of the energy supply unit (10).

13. The method according to claim 12, wherein, If the inverter (3) does not receive a predetermined amount of energy from the photovoltaic generator (2) and the AC power grid (5), the energy supply unit (10) of the photovoltaic system (1) supplies energy only to the inverter (3) in the deadlock prevention mode of the energy supply unit (10).

14. The method according to any one of claims 11 to 13, wherein, If the state of charge (SoC) of the energy supply unit (10) reaches a predetermined level higher than each predetermined SoC level L1, L2 or L3, an SoC warning signal is automatically triggered.

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