A converter control method and related apparatus

Abstract

The application provides a converter control method and related device, and relates to the field of converters. In the application, the alternating current side of the converter is connected with a power grid and a load, the direct current side of the converter is connected with a photovoltaic string and / or a battery, and the converter can communicate with an energy management system. On this basis, in the case that an arc fault is detected, reactive power demand information issued by the energy management system is received, and pure reactive power is output based on the reactive power demand information. When the converter outputs pure reactive power, there is no current in the direct current cable, and the arc can be eliminated through the currentless state. In the process of extinguishing the arc, the pure reactive power can also provide the reactive power required by the load, thereby guaranteeing the working stability of the load. In addition, the pure reactive power output by the converter can also maintain the stability of the grid-side voltage and frequency, thereby guaranteeing the stable and reliable operation of the system.

Description

Technical Field

[0001] This application relates to the field of converters, and more specifically, to a converter control method and related apparatus. Background Technology

[0002] When the converter detects an electric arc, it uses components such as a BOOST converter, inverter drive, or DC / DC converter to perform arc suppression control, reducing the DC current to 0A and eliminating the arc. However, arc suppression may affect the stability of the load, grid voltage, and frequency, causing the entire system to be unable to operate stably or reliably, or even to fail to operate at all. Summary of the Invention

[0003] In view of this, this application provides a converter control method and related apparatus to solve the problem that during wave blocking and arc extinguishing, the stability of the load operation, grid-side voltage and frequency may be affected, resulting in the entire system being unable to operate stably and reliably or failing to operate.

[0004] To solve the above-mentioned technical problems, this application adopts the following technical solution:

[0005] In a first aspect, this application discloses a converter control method, wherein the AC side of the converter is connected to the power grid and a load, the DC side of the converter is connected to a photovoltaic string and / or a battery, and the converter is capable of communicating with an energy management system; the converter control method includes:

[0006] In the event of an arc fault, the system receives reactive power demand information from the energy management system.

[0007] Output pure reactive power based on reactive power demand information.

[0008] Optionally, receiving reactive power demand information from the energy management system includes:

[0009] Receive reactive power demand information sent by the energy management system when an arc fault is detected;

[0010] Alternatively, it can output an arc processing request to the energy management system and receive reactive power demand information from the energy management system.

[0011] Optionally, outputting pure reactive power based on reactive power demand information includes:

[0012] Extract the target value of reactive power from the reactive power demand information;

[0013] Switch the output power to pure reactive power that matches the target value of reactive power.

[0014] Optionally, the process of switching the output power to pure reactive power that matches the target reactive power value further includes:

[0015] When the arc is extinguished and the current moment is the start of the output of pure reactive power, receive the state adjustment command sent by the energy management system;

[0016] In response to the state adjustment command, perform a state adjustment operation.

[0017] Optionally, after outputting pure reactive power based on reactive power demand information, the method further includes:

[0018] If a real arc fault is confirmed, a fault message will be output.

[0019] Optionally, determining the existence of a real arc fault includes:

[0020] Adjust the operating status;

[0021] Detect the operating characteristics of the converter;

[0022] If the operating characteristics are determined to meet the conditions for judging a real arc fault, then a real arc fault is determined to exist.

[0023] Optionally, the operating characteristics include the current signal and / or voltage signal of the converter:

[0024] Determining that the operational characteristics satisfy the criteria for judging a real arc fault includes:

[0025] If the operating characteristics meet the characteristics of a real electric arc, then the operating characteristics are determined to meet the conditions for judging a real electric arc fault.

[0026] Optionally, it also includes:

[0027] If no reactive power demand information is received from the energy management system, the arc will be eliminated using the wave blocking control method.

[0028] Secondly, this application discloses a converter control device, wherein the AC side of the converter is connected to the power grid and a load, the DC side of the converter is connected to a photovoltaic string and / or a battery, and the converter is capable of communicating with an energy management system; the converter control device includes:

[0029] The information receiving module is used to receive reactive power demand information sent by the energy management system when an arc fault is detected.

[0030] The power regulation module is used to output pure reactive power based on reactive power demand information.

[0031] Thirdly, this application discloses a converter, which is used to perform the converter control method described above.

[0032] Fourthly, this application discloses a photovoltaic system including the aforementioned converter.

[0033] Fifthly, this application discloses an optical storage system, including the aforementioned converter.

[0034] Sixthly, this application discloses an energy storage system including the aforementioned converter.

[0035] This application provides a converter control method and related apparatus. In this application, the AC side of the converter is connected to the power grid and the load, and the DC side of the converter is connected to a photovoltaic string and / or batteries. The converter can communicate with an energy management system. Based on this, when an arc fault is detected, the converter receives reactive power demand information from the energy management system and outputs pure reactive power based on the reactive power demand information. When the converter outputs pure reactive power, there is no current in the DC cable. This current-free state can eliminate the arc. Furthermore, during the arc extinguishing process, the output of pure reactive power can also provide the reactive power required by the load, ensuring the stability of the load operation. In addition, the output of pure reactive power by the converter can also maintain the stability of the grid-side voltage and frequency, ensuring the stable and reliable operation of the system. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the structure of a photovoltaic system provided in an embodiment of this application;

[0038] Figure 2 This is a schematic diagram of the structure of a photovoltaic energy storage system provided in an embodiment of this application;

[0039] Figure 3 A flowchart of a converter control method provided in an embodiment of this application;

[0040] Figure 4 A flowchart illustrating a power adjustment method provided in an embodiment of this application;

[0041] Figure 5 A flowchart illustrating a state adjustment method provided in this application embodiment;

[0042] Figure 6A flowchart of another converter control method provided in the embodiments of this application;

[0043] Figure 7 This is a schematic diagram of a converter control device provided in an embodiment of this application. Detailed Implementation

[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] When an electric arc is detected, converters such as photovoltaic inverters, energy storage inverters, or energy storage converters will use components such as BOOST, inverter drive, or DC / DC converters to perform wave blocking control. Once the DC current of the photovoltaic / battery string where the electric arc actually occurred drops to 0A, the electric arc will disappear.

[0046] Because the converter no longer outputs reactive power during waveform blocking control, it cannot meet the reactive power demand of the load, thus affecting the load's operational stability. Furthermore, the reduction in reactive power output by the converter makes it impossible to maintain grid-side voltage and frequency stability, leading to the entire system failing to operate stably or reliably, or even malfunctioning.

[0047] To address the aforementioned issues, this embodiment employs a method of outputting pure reactive power to eliminate electric arcs, thereby providing the reactive power required by the load and ensuring load operational stability. Furthermore, it also maintains grid-side voltage and frequency stability, ensuring the normal and reliable operation of the system.

[0048] Based on the above, one embodiment of this application provides a converter control method, wherein the executing entity can be a converter, such as a photovoltaic inverter, an energy storage inverter, or an energy storage converter.

[0049] In real-world scenarios, the AC side of the converter is connected to the power grid and the load, while the DC side of the converter is connected to photovoltaic strings and / or batteries.

[0050] In practice, the converter can be installed in photovoltaic systems, photovoltaic-storage systems, and energy storage systems.

[0051] In one implementation, taking the converter as the inverter as an example, the photovoltaic system or energy storage system typically consists of N inverters + M photovoltaic strings / cells + L EMS (Energy Management System) units to meet the needs of the load and the grid side. Here, N, M, and L are positive integers.

[0052] In one implementation, the structural diagram of the photovoltaic system can be as follows: Figure 1 As shown, the photovoltaic system consists of two grid-connected inverters (PV Inverter A and PV Inverter B), one EMS device, loads, and the power grid. The AC side of the inverters is connected to the power grid and the load (such as a charging pile), while the DC side is connected to the photovoltaic (PV) string. The electrical energy generated by the PV string can be output to the PV inverter, which performs the corresponding conversion operations and then outputs the electrical energy to the load and the power grid.

[0053] During inverter operation, the inverter can communicate with the EMS (Electronic Management System). The EMS system interacts with the photovoltaic inverter, load, and grid based on a pre-defined communication protocol. The EMS system can adjust the operating mode and output power of the photovoltaic inverter within the system to meet the specific needs of the grid, load, or customer.

[0054] In the structure of an energy storage system, compared to a photovoltaic structure, the photovoltaic strings can be replaced with batteries, and the rest of the structure is similar.

[0055] Compared to photovoltaic (PV) systems and energy storage systems, PV-storage systems incorporate both PV strings and batteries. A schematic diagram of its architecture can be found here. Figure 2 As shown. Figure 2 The photovoltaic system consists of two energy storage inverters (energy storage inverters A and B), one EMS device load, and the power grid.

[0056] The AC side of the inverter is connected to the power grid and the load, while the DC side of the inverter is connected to the photovoltaic string and the battery.

[0057] During the operation of a photovoltaic-storage system, the electrical energy generated by the photovoltaic strings can be converted by an energy storage inverter and stored in batteries, or used by loads and the grid. When the photovoltaic strings' power generation capacity is insufficient, the inverter can use the electrical energy in the batteries to supply power to loads and the grid.

[0058] The EMS system interacts with the energy storage inverter, load, and grid based on a set communication protocol. The EMS system can adjust the operating mode and output power of the energy storage inverter within the system to meet the specific needs of the grid, load, or customer.

[0059] In the aforementioned photovoltaic, photovoltaic-storage, and energy storage systems, when an electric arc occurs, the arc is extinguished by controlling the photovoltaic inverter and the energy storage inverter to output pure reactive power or by using wave blocking control.

[0060] Specifically, refer to Figure 3 The converter control method may include:

[0061] S11. Upon detecting an arc fault, receive reactive power demand information from the energy management system.

[0062] In real-world scenarios, cable damage or faulty terminal wiring can easily lead to arcing. The converter can determine if an arcing fault has occurred by detecting current and / or voltage. If the detected current and / or voltage characteristics match those of an arc, then an arcing phenomenon has occurred.

[0063] If the converter detects an arcing fault, two methods can be used to extinguish the arc. One method is arc suppression, where the DC current of the corresponding cable is reduced to 0A, thus eliminating the arcing phenomenon. The other method is arc suppression by generating pure reactive power. When extinguishing the arc by generating pure reactive power, the converter does not need to perform arc suppression control; simply changing the converter's output control strategy to output pure reactive power will eliminate the arc. When the converter generates pure reactive power, there is no current in the DC cable, and this current-free state eliminates the arc, achieving arc elimination by outputting pure reactive power. In this method, the converter's generation of pure reactive power can also provide the necessary reactive power to the load, maintaining grid-side voltage and frequency stability and ensuring the stable and reliable operation of the entire system.

[0064] Given the existence of the two arc extinguishing methods mentioned above, the choice of which arc extinguishing method to use can be based on whether there is a reactive power requirement.

[0065] Whether there is reactive power demand can be determined through EMS.

[0066] The EMS (Electronic Management System) determines whether there is reactive power demand by combining customer commands, load, and grid requirements. If the EMS identifies or receives a corresponding reactive power demand, it allocates a reactive power output value to each converter based on the reactive power output capability of each converter. Then, it sends the corresponding reactive power demand information to the relevant converter. Upon receiving this information, the converter adjusts its operating mode and output power to meet the corresponding reactive power demand. In practical scenarios, the converter passively fulfills the EMS system's requirements; it outputs reactive power only when the EMS determines there is a reactive power demand, and does not output reactive power when there is no demand.

[0067] The reactive power demand information includes the reactive power target value of the converter where the arc occurs. If the reactive power target value is zero or there is no reactive power demand information, it means that the converter does not need to output pure reactive power, that is, there is no reactive power demand. In this case, the method of outputting pure reactive power to extinguish the arc cannot be used. Instead, the arc extinguishing method of wave blocking can be used.

[0068] If the target reactive power value is not zero, it indicates that the converter that is experiencing an arc needs to output reactive power to provide reactive power support. In this case, arc extinguishing can be performed by generating pure reactive power. At this time, pure reactive power is output according to the target value. Since the converter only outputs reactive power and not active power, there is no current in the DC cable, and this current-free state can eliminate the arc. That is, while outputting the required pure reactive power, the arc extinguishing effect can also be achieved using the output pure reactive power.

[0069] For example, if an EMS system requires 100kVar reactive power, and the N-1 (N is a positive integer) converters (excluding the one where the arc occurs) can only output a maximum of 90kVar reactive power, then the converter where the arc occurs needs to output 10kVar reactive power to meet the reactive power requirement and simultaneously extinguish the arc.

[0070] S12. Output pure reactive power based on reactive demand information.

[0071] In real-world scenarios, the converter's output of pure reactive power can be time-limited or time-unlimited, depending on the reactive power demand.

[0072] In this embodiment, when the converter receives the reactive power demand information sent by the EMS, it adjusts its own working mode and output power according to the reactive power demand information, so that the converter only outputs reactive power and simultaneously achieves arc extinguishing.

[0073] In this embodiment, the AC side of the converter is connected to the power grid and the load, while the DC side is connected to a photovoltaic string and / or batteries. The converter can communicate with the energy management system. Based on this, in the event of an arc fault, it receives reactive power demand information from the energy management system and outputs pure reactive power. When the converter outputs pure reactive power, there is no current in the DC cable, which eliminates the arc. Furthermore, during the arc extinguishing process, the output of pure reactive power also provides the reactive power required by the load, ensuring load stability. Additionally, the converter's output of pure reactive power can maintain grid-side voltage and frequency stability, ensuring stable and reliable system operation. Moreover, this reactive power arc extinguishing method also reduces line losses and other advantages.

[0074] Furthermore, in arc suppression schemes that use waveform blocking, if the converter simultaneously outputs active and reactive power before an arc occurs, the converter will be completely unable to output reactive power during arc suppression. This could affect the stability of downstream loads, grid-side voltage, and frequency stability, with the impact becoming more pronounced when the entire system frequently detects arcs. In contrast, the reactive power-generating arc suppression scheme in this application can output reactive power normally after arc suppression, ensuring the stability of downstream loads, grid-side voltage, and frequency.

[0075] In another implementation of this application, when the converter detects an electric arc, it can interact with the EMS system to confirm whether reactive power needs to be generated, or the EMS system can actively send reactive power control information. Based on this, there are two implementation methods for receiving reactive power demand information from the energy management system, which will be described separately below.

[0076] 1. The first implementation method.

[0077] Receive reactive power demand information sent by the energy management system when an arc fault is detected.

[0078] Specifically, the EMS has arc monitoring capabilities, enabling it to monitor whether arc faults occur in the converters connected to the EMS. When the EMS system detects an arc in a converter, it controls the converter to execute either a reactive power generation arc extinguishing strategy or a wave blocking arc extinguishing strategy based on the judgment result of whether there is reactive power demand. If it is confirmed that there is reactive power demand in the EMS system and the converter experiencing the arc needs to output reactive power, it can actively send reactive power demand information to the converter. Based on the control of the EMS, the converter outputs pure reactive power to achieve the arc extinguishing effect. At the same time, it can also provide the reactive power required by the load and stabilize the grid-side voltage and frequency.

[0079] 2. The second implementation method.

[0080] Specifically, the converter outputs an arc processing request to the energy management system and receives reactive power demand information from the energy management system.

[0081] To elaborate, the first implementation method is for the EMS to actively send reactive power demand information. In addition, the converter that is experiencing an arc can actively interact with the EMS system. In this case, the EMS can send reactive power demand information when it receives a request from the converter's output.

[0082] Specifically, when the converter detects an arc fault, it can output an arc handling request to the EMS. After receiving the arc handling request, the EMS controls the converter to execute a strategy of generating reactive power to extinguish the arc or a strategy of blocking the arc, based on the judgment result of whether there is reactive power demand. If it is confirmed that there is reactive power demand in the EMS system and the converter where the arc occurred needs to output reactive power, it can actively send reactive power demand information to the converter. Based on the control of the EMS, the converter outputs pure reactive power to achieve the arc extinguishing effect, and at the same time can provide the reactive power required by the load, as well as stabilize the grid-side voltage and frequency.

[0083] In practical scenarios, either the first or second implementation method described above can be used to achieve the interaction between the EMS and the converter, ultimately realizing the effect of arc extinguishing by generating reactive power. For reliable arc extinguishing, both methods can be used simultaneously. When an arc occurs, the EMS actively sends reactive power demand information, and simultaneously, after the converter reports an arc handling request, the EMS sends reactive power demand information. This ensures that even if one of the EMS or the converter malfunctions and fails to detect the arc fault, the converter's arc anomaly can still be reliably detected, guaranteeing the reliability of arc extinguishing.

[0084] In another implementation of this application, when the converter outputs pure reactive power based on reactive power demand information, it can be done according to... Figure 4 The steps are as follows. Specifically, outputting pure reactive power based on reactive power demand information includes:

[0085] S21. Extract the reactive power target value from the reactive power demand information.

[0086] Specifically, after receiving reactive power demand information, the converter can parse the reactive power demand information based on the communication protocol to obtain the reactive power target value in the reactive power demand information.

[0087] S22. Switch the output power to pure reactive power that matches the target value of reactive power.

[0088] Specifically, the converter's current operating mode may not be a pure reactive power output mode. Therefore, the converter needs to switch modes to output pure reactive power. For example, if the converter is simultaneously outputting reactive and active power when it needs to output pure reactive power, the converter needs to reduce the active power value and gradually switch to a pure reactive power output mode.

[0089] Generally, current standards and specifications require that the time from the occurrence of an electric arc to the complete elimination of the arc by the converter should not exceed 2.5 seconds. This time can be understood as the time required from the occurrence of an electric arc to the moment when the converter outputs pure reactive power. Therefore, in practical scenarios, the time required for the converter to switch from the current operating mode to the pure reactive power output mode should not exceed 2.5 seconds.

[0090] When the converter switches to the pure reactive power output mode, it outputs pure reactive power according to the target reactive power value. For example, if the target reactive power value is 10kVar, the converter outputs 10kVar of pure reactive power.

[0091] Understandably, the converter can output pure reactive power for a period of time, which is configured by the EMS.

[0092] Normally, after the converter outputs pure reactive power, there is no current in the DC cable. This current-free state can eliminate the electric arc, thus eliminating the arc by outputting pure reactive power. In this embodiment, if the converter outputs pure reactive power for a continuous period of time, it can ensure the elimination of the arc and meet the reactive power requirements of the load.

[0093] In practical applications, the reactive power demand of the load is constantly changing. For example, at one moment, 100kVar of reactive power is needed, but at the next moment, the load stops and no longer needs that reactive power. Furthermore, customer commands and grid demands also change in real time, sometimes requiring more reactive power one moment and less the next. Therefore, in this embodiment, during the process of the EMS issuing reactive power demand information to control the converter's output of pure reactive power, if the EMS determines that a reduction in reactive power is needed based on the reactive power demand, and if analysis determines that the converter experiencing the arc needs to stop or reduce its reactive power output, it can issue a state adjustment command to the converter to stop or reduce its reactive power output. In another implementation of this application, at this time, referring to... Figure 5 The process of switching the output power to pure reactive power that matches the target reactive power value also includes:

[0094] S31. When the arc is eliminated and the current moment is the start moment of outputting pure reactive power, receive the state adjustment command sent by the energy management system.

[0095] Specifically, when the EMS issues a status adjustment command, the converter can receive and respond to the command, adjusting the output power based on the current operating mode.

[0096] In real-world scenarios, when the EMS issues a status adjustment command, the converter may be in the process of switching from other operating modes to a pure reactive power output mode, or it may have successfully switched to a pure reactive power output mode. If the switch to pure reactive power output mode is successful, the converter outputs pure reactive power. When the converter is outputting pure reactive power, there is no current in the DC cable, and this current-free state can eliminate the arc. Therefore, after receiving the EMS status adjustment command, the output power can be adjusted directly according to the status adjustment command to avoid the problem of excessive reactive power output caused by continued reactive power output.

[0097] It should be noted that in a special case, when the arc has been eliminated and the current moment is the start of outputting pure reactive power, the state adjustment command sent by the energy management system is received. That is, when the arc has been eliminated at the moment when the converter is exactly outputting pure reactive power and the state adjustment command is received from the EMS, since the converter has already output pure reactive power and the arc has been eliminated, the state adjustment can be performed according to the state adjustment command.

[0098] S32. Respond to the state adjustment command and perform a state adjustment operation.

[0099] Specifically, when the converter is switching from other operating modes to a pure reactive power output mode, it may be outputting active power, but the active power value is decreasing in preparation for switching to pure reactive power. During the decrease in active power, the current value in the cable decreases, and the arc may disappear as the current value decreases, or it may continue to exist. If the arc disappears and the current moment is the start of pure reactive power output, and a state adjustment command is received, then since the arc has been eliminated, a state adjustment operation is performed based on this command, such as adjusting the output reactive power value, or adjusting the output reactive and active power values.

[0100] In another implementation of this application, after outputting pure reactive power based on reactive power demand information, a fault prompt message is output when a real arc fault is determined to exist.

[0101] Specifically, after outputting pure reactive power based on reactive power demand information, it can be ensured that the arc has been eliminated. At this point, it should be determined whether the arc was a real arc or a false arc caused by factors such as sunlight or grid fluctuations, i.e., whether a real arc fault exists. If it is a false arc, the converter can continue to generate waves; if it is a real arc, the converter can output fault indication information for subsequent maintenance operations.

[0102] In one implementation, determining the existence of a real arc fault can be achieved by controlling the converter to adjust its operating state and re-transmit the arc. If the previous arc was a real arc, it indicates that the location where the arc occurred has been damaged, and the photovoltaic / cell string will still not output current or the output current will be abnormal, thus reporting an arc fault. Therefore, in this embodiment, the operating characteristics of the converter can be detected. If the operating characteristics meet the criteria for determining a real arc fault, then a real arc fault is determined to exist.

[0103] Understandably, the operating characteristics include the current signal and / or voltage signal of the converter; that is, the operating characteristics may be only a current signal, only a voltage signal, or both current and voltage signals. Subsequently, the current and / or voltage signals can be sampled, processed, and compared to determine whether they conform to the characteristics of a real electric arc to confirm whether a real electric arc has occurred.

[0104] In one implementation, if the operating characteristics meet the characteristics of a real electric arc, such as the current value in the current signal being a set value, or the difference in the current value in the current signal being large before and after the occurrence of the arc, it is determined that the operating characteristics meet the judgment conditions for a real electric arc fault.

[0105] In another implementation of this application, if the reactive power target value in the reactive power demand information sent by the EMS is zero, or if the reactive power demand information sent by the EMS is not received, or if the EMS sends a message prohibiting the output of reactive power, the arc can be eliminated by wave blocking control. At this time, wave blocking control is performed using components such as BOOST, inverter drive, or DC / DC. When the DC current of the photovoltaic / battery string that actually experiences the arcing phenomenon drops to 0A, the arcing phenomenon disappears.

[0106] In another implementation of this application, Figure 6 This is the complete arc elimination method in the embodiments of this application.

[0107] The first step was that the converter detected an electric arc.

[0108] The second step involves communication between the converter and the EMS system to confirm whether the converter can generate pure reactive power.

[0109] This step can be implemented using reactive power demand information sent by the EMS. In this case, the converter can receive reactive power demand information sent by the energy management system when an arc fault is detected. Alternatively, the converter can output an arc handling request to the energy management system and receive reactive power demand information from the energy management system.

[0110] The third step is for the converter to continuously generate pure reactive power.

[0111] If the reactive power demand information indicates that the converter can generate pure reactive power, then the converter outputs pure reactive power. If the reactive power demand information indicates that the converter cannot generate reactive power, then a wave blocking control method is used to eliminate the arc.

[0112] The fourth step is for the converter to confirm whether a real electric arc has occurred.

[0113] Fifth, if the converter confirms that a real electric arc has occurred, it will report the fault and instruct the customer to eliminate the potential hazard.

[0114] In this embodiment, when an electric arc occurs, the converter and the EMS system communicate in real time. If the converter can generate pure reactive power, it can extinguish the arc by using pure reactive power. At the same time, generating pure reactive power can meet the required reactive power load and support the grid side to maintain grid-side voltage and frequency stability. In addition, it can also reduce line losses.

[0115] Based on the embodiments of the above-described converter control method, another embodiment of this application provides a converter control device, wherein the AC side of the converter is connected to the power grid and the load, the DC side of the converter is connected to a photovoltaic string and / or a battery, and the converter is capable of communicating with an energy management system; see reference Figure 7 The converter control device may include:

[0116] Information receiving module 11 is used to receive reactive power demand information sent by the energy management system when an arc fault is detected;

[0117] The power regulation module 12 is used to output pure reactive power based on reactive power demand information.

[0118] In one implementation, the information receiving module 11 includes:

[0119] The first processing submodule is used to receive reactive power demand information sent by the energy management system when an arc fault is detected.

[0120] The second processing submodule is used to output an arc processing request to the energy management system and receive reactive power demand information issued by the energy management system.

[0121] In one implementation, the power regulation module 12 includes:

[0122] The data parsing submodule is used to extract the reactive power target value from the reactive power demand information;

[0123] The power regulation submodule is used to switch the output power to pure reactive power that matches the target value of reactive power.

[0124] One implementation also includes:

[0125] The instruction receiving module is used to receive the state adjustment instruction sent by the energy management system when the arc is extinguished and the current moment is the start moment of outputting pure reactive power.

[0126] The power control module is used to respond to the state adjustment command and perform state adjustment operations.

[0127] One implementation also includes:

[0128] The information output module is used to output fault prompt information when a real electric arc fault is determined to exist.

[0129] In one implementation, the information output module includes:

[0130] The state switching submodule is used to adjust the running state;

[0131] A feature detection submodule is used to detect the operational features of the converter;

[0132] The fault determination submodule is used to determine the existence of a real arc fault when the operating characteristics meet the judgment conditions for a real arc fault.

[0133] In one implementation, the operating characteristics include the current signal and / or voltage signal of the converter: the fault determination submodule is specifically used for:

[0134] If the operating characteristics meet the characteristics of a real electric arc, then the operating characteristics are determined to meet the conditions for judging a real electric arc fault.

[0135] One implementation also includes:

[0136] The arc suppression module is used to eliminate electric arcs by means of wave suppression control if no reactive power demand information is received from the energy management system.

[0137] In this embodiment, the AC side of the converter is connected to the power grid and the load, while the DC side is connected to a photovoltaic string and / or batteries. The converter can communicate with the energy management system. Based on this, in the event of an arc fault, it receives reactive power demand information from the energy management system and outputs pure reactive power. When the converter outputs pure reactive power, there is no current in the DC cable. This current-free state can eliminate the arc. Furthermore, during the arc extinguishing process, the output of pure reactive power can also provide the reactive power required by the load, ensuring the stability of the load operation. In addition, the converter's output of pure reactive power can also maintain the stability of the grid-side voltage and frequency, ensuring the stable and reliable operation of the system.

[0138] It should be noted that the working process of each module and sub-module in this embodiment is described in the corresponding descriptions in the above embodiments.

[0139] Another embodiment of this application also provides a converter, including a converter control method described above.

[0140] Another embodiment of this application also provides a photovoltaic system including the converter described above.

[0141] Another embodiment of this application also provides an optical storage system, including the converter described above.

[0142] Another embodiment of this application also provides an energy storage system, including the converter described above.

[0143] For details on the implementation of photovoltaic systems, photovoltaic-energy storage systems, and energy storage systems, please refer to the corresponding explanations above.

[0144] This application also provides a computer program product including computer-readable instructions, which, when executed on an electronic device, cause the electronic device to implement any of the converter control methods provided in this application.

[0145] This application also provides a computer-readable storage medium that carries one or more computer programs. When the one or more computer programs are executed by an electronic device, the electronic device can implement any of the converter control methods provided in this application.

[0146] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A converter control method, characterized in that, The AC side of the converter is connected to the power grid and the load, and the DC side of the converter is connected to a photovoltaic string and / or batteries. The converter is capable of communicating with an energy management system. The converter control method includes: In the event of an arc fault, the system receives reactive power demand information from the energy management system. Output pure reactive power based on reactive power demand information.

2. The converter control method according to claim 1, characterized in that, Receiving reactive power demand information from the energy management system, including: Receive reactive power demand information sent by the energy management system when an arc fault is detected; Alternatively, it can output an arc processing request to the energy management system and receive reactive power demand information from the energy management system.

3. The converter control method according to claim 1 or 2, characterized in that, Outputting pure reactive power based on reactive demand information includes: Extract the target value of reactive power from the reactive power demand information; Switch the output power to pure reactive power that matches the target value of reactive power.

4. The converter control method according to claim 3, characterized in that, The process of switching the output power to pure reactive power that matches the target reactive power value also includes: When the arc is extinguished and the current moment is the start of the output of pure reactive power, receive the state adjustment command sent by the energy management system; In response to the state adjustment command, perform a state adjustment operation.

5. The converter control method according to claim 1, characterized in that, After outputting pure reactive power based on reactive power demand information, it also includes: If a real arc fault is confirmed, a fault message will be output.

6. The converter control method according to claim 5, characterized in that, The presence of a real arc fault was confirmed, including: Adjust the operating status; Detect the operating characteristics of the converter; If the operating characteristics are determined to meet the conditions for judging a real arc fault, then a real arc fault is determined to exist.

7. The converter control method according to claim 6, characterized in that, The operating characteristics include the current signal and / or voltage signal of the converter: Determining that the operational characteristics satisfy the criteria for judging a real arc fault includes: If the operating characteristics meet the characteristics of a real electric arc, then the operating characteristics are determined to meet the conditions for judging a real electric arc fault.

8. The converter control method according to claim 1, characterized in that, Also includes: If no reactive power demand information is received from the energy management system, the arc will be eliminated using the wave blocking control method.

9. A converter control device, characterized in that, The AC side of the converter is connected to the power grid and the load, and the DC side of the converter is connected to a photovoltaic string and / or batteries. The converter is capable of communicating with an energy management system. The converter control device includes: The information receiving module is used to receive reactive power demand information sent by the energy management system when an arc fault is detected. The power regulation module is used to output pure reactive power based on reactive power demand information.

10. A converter, characterized in that, The package is used to perform the converter control method as described in any one of claims 1 to 8.

11. A photovoltaic system, characterized in that, Includes the converter as described in claim 10.

12. A photovoltaic energy storage system, characterized in that, Includes the converter as described in claim 10.

13. An energy storage system, characterized in that, Includes the converter as described in claim 10.

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