Control method and device of charge-discharge module, control equipment and storage medium

Abstract

The application provides a control method and device of a charge-discharge module, a control equipment and a storage medium. The method comprises: when the charge-discharge module is in a low-voltage ride-through state, acquiring instantaneous values of voltages of each phase of a power grid; if it is detected that the instantaneous values of the voltages of each phase of the power grid satisfy a preset zero-voltage ride-through condition, controlling a phase-locked loop to stop working; wherein the phase-locked loop is used to perform phase locking on the power grid voltage when working, and stop performing phase locking on the power grid voltage when stopping working; the preset zero-voltage ride-through condition comprises that a maximum value of the instantaneous values of the voltages of each phase of the power grid is less than a preset voltage value, and a duration that the maximum value of the instantaneous values of the voltages of each phase of the power grid is less than the preset voltage value is greater than a preset duration. The application can ensure that there is no phase difference between an output signal of the phase-locked loop and an actual power grid voltage at a power grid voltage recovery moment, bus overvoltage protection does not occur, the zero-voltage ride-through process can be normally completed, and the stability of the charge-discharge module is improved.

Description

Technical Field

[0001] This invention relates to the field of grid connection technology, and in particular to a control method, device, control equipment, and storage medium for a charging and discharging module. Background Technology

[0002] As a grid-connected machine, the charging / discharging module enables bidirectional energy flow between the grid and battery sides. High and low voltage ride-through is a crucial function for grid-connected machines, enhancing their adaptability to grid voltage.

[0003] Currently, the control scheme for high and low voltage ride-through of the charging and discharging module may encounter bus overvoltage protection during zero voltage ride-through when the grid recovers, leading to zero voltage ride-through failure and affecting the stability of the charging and discharging module. Summary of the Invention

[0004] This invention provides a control method, device, control equipment, and storage medium for a charging and discharging module to solve the problem that in the prior art, during zero-voltage ride-through, the bus overvoltage protection will occur probabilistically at the moment of grid restoration, leading to zero-voltage ride-through failure and affecting the stability of the charging and discharging module.

[0005] In a first aspect, embodiments of the present invention provide a control method for a charging and discharging module, the control method for the charging and discharging module comprising:

[0006] When the charging and discharging module is in a low voltage ride-through state, it acquires the instantaneous voltage values ​​of each phase of the power grid.

[0007] If the instantaneous voltage values ​​of each phase of the power grid meet the preset zero-voltage ride-through condition, the phase-locked loop is controlled to stop working.

[0008] The phase-locked loop (PLL) is used to lock the grid voltage during operation and to stop locking the grid voltage when the operation stops. The preset zero-voltage ride-through condition includes the maximum instantaneous value of the voltage of each phase of the grid being less than the preset voltage value, and the duration for which the maximum instantaneous value of the voltage of each phase of the grid is less than the preset voltage value being greater than the preset duration.

[0009] In one possible implementation, before acquiring the instantaneous values ​​of the voltages of each phase of the power grid when the charging / discharging module is in a low-voltage ride-through state, the control method for the charging / discharging module further includes:

[0010] Obtain the percentage drop in grid voltage;

[0011] If the percentage drop in grid voltage is less than a preset percentage, the charge / discharge module is controlled to enter a low-voltage ride-through state.

[0012] In one possible implementation, controlling the charge / discharge module to enter a low-voltage ride-through state includes:

[0013] The control module outputs reactive grid-connected current; the phase of the reactive grid-connected current is the same as the phase of the output signal of the phase-locked loop.

[0014] In one possible implementation, obtaining the percentage drop in grid voltage includes:

[0015] Obtain the instantaneous values ​​of the three-phase power grid voltage;

[0016] Transform the instantaneous values ​​of the three-phase grid voltage from the ABC coordinate system to the DQ0 coordinate system to obtain the D-axis component values ​​of the grid voltage;

[0017] The percentage drop in grid voltage is obtained based on the D-axis component of the grid voltage and the rated grid voltage.

[0018] In one possible implementation, after the phase-locked loop stops operating, the control method for the charging and discharging module further includes:

[0019] When the instantaneous voltage values ​​of each phase of the power grid are detected to no longer meet the preset zero-voltage ride-through condition, the phase-locked loop (PLL) restarts operation.

[0020] In one possible implementation, the process of determining the preset voltage value and the preset duration includes:

[0021] The phase difference between the phase of the phase-locked loop output signal and the actual phase of the grid voltage is obtained during the time from the actual power outage to the detection of the power outage.

[0022] When the phase difference is less than the preset phase difference value, the preset voltage value and preset duration are determined.

[0023] In a second aspect, embodiments of the present invention provide a control device for a charging and discharging module, the control device for the charging and discharging module comprising:

[0024] The acquisition module is used to acquire the instantaneous voltage values ​​of each phase of the power grid when the charging and discharging module is in a low voltage ride-through state.

[0025] The first control module is used to control the phase-locked loop to stop working if the instantaneous voltage values ​​of each phase of the power grid meet the preset zero-voltage ride-through condition.

[0026] The phase-locked loop (PLL) is used to lock the grid voltage during operation and to stop locking the grid voltage when the operation stops. The preset zero-voltage ride-through condition includes the maximum instantaneous value of the voltage of each phase of the grid being less than the preset voltage value, and the duration for which the maximum instantaneous value of the voltage of each phase of the grid is less than the preset voltage value being greater than the preset duration.

[0027] In one possible implementation, the control device for the charging and discharging module further includes:

[0028] The second control module is used to obtain the percentage drop in grid voltage; if the percentage drop in grid voltage is less than a preset percentage, the charging and discharging module is controlled to enter the low voltage ride-through state.

[0029] Thirdly, embodiments of the present invention provide a control device, including a processor and a memory, wherein the memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory to execute the control method of the charging and discharging module as described in the first aspect or any possible implementation thereof.

[0030] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the control method for the charging and discharging module as described in the first aspect or any possible implementation thereof.

[0031] This invention provides a control method, device, control equipment, and storage medium for a charging and discharging module. When the charging and discharging module is in a low-voltage ride-through state, and the maximum instantaneous voltage value of each phase of the power grid is less than a preset voltage value, and the duration for which the maximum instantaneous voltage value of each phase of the power grid is less than the preset voltage value is greater than a preset duration, the charging and discharging module is determined to have entered a zero-voltage ride-through state. At this time, the phase-locked loop (PLL) is controlled to stop working to ensure that the PLL can exit quickly. This ensures that when the power grid voltage recovers, the PLL output signal and the actual power grid voltage no longer have a phase difference, preventing bus overvoltage protection and enabling the normal completion of the zero-voltage ride-through process, thus improving the stability of the charging and discharging module. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a waveform diagram of the existing charge / discharge module control scheme after fitting the brush wave data during bus overvoltage protection;

[0034] Figure 2 This is a schematic diagram of the control method for the charging and discharging module provided in an embodiment of the present invention;

[0035] Figure 3This is a schematic diagram of another control method for a charging and discharging module provided in an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the waveform after fitting the brush wave data using the control method of the charging and discharging module provided in the embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram of the structure of the control device for the charging and discharging module provided in an embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram of the control device provided in an embodiment of the present invention. Detailed Implementation

[0039] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described below in conjunction with the accompanying drawings.

[0041] A charging / discharging module can be a charging / discharging circuit, with one end connected to the battery and the other end connected to the power grid. It can include DC-DC modules and DC-AC modules. The charging / discharging module enables bidirectional flow of energy between the power grid and the battery, that is, it can enable the power grid to charge the battery and the battery to discharge to the power grid.

[0042] Currently, the existing control scheme for charging and discharging modules considers the current state as zero voltage ride-through when the percentage drop in grid voltage is less than a small value, such as less than 10%. At this time, since there is no grid voltage, phase-locked loop (PLL) is no longer performed to prevent the failure of the ride-through due to phase-locked loop error.

[0043] However, when using the existing control scheme described above for the charge / discharge module, system bus overvoltage protection will probabilistically occur during the zero-voltage ride-through recovery phase. When reproducing the problem, the system variables were refreshed using a common debugging platform, and the results were as follows... Figure 1 As shown.

[0044] in, Figure 1 In the diagram, channel A represents the instantaneous grid voltage value sampled by the DSP, channel B represents the sin value of the line voltage output by the phase-locked loop, and channel C represents the percentage drop in grid voltage.

[0045] Depend on Figure 1 It can be seen that after the grid voltage recovers, there is a phase difference between the line voltage sin value output by the phase-locked loop and the sampled grid voltage. However, the phase of the grid-connected current is the same as the phase of the line voltage sin value output by the phase-locked loop. Therefore, after the grid voltage recovers, there is a phase difference between the grid-connected current and the grid voltage, which causes grid energy to flow back to the bus, and ultimately the system is protected due to bus overvoltage.

[0046] Further analysis reveals that the system begins to generate reactive current when the grid voltage drops to 90%, and the phase-locked loop (PLL) only stops operating when the grid voltage drops to 10%. When the grid voltage drop percentage is between 10% and 90%, the actual grid voltage is zero because the external operation is a zero-voltage ride-through. The sampled grid voltage is the voltage drop across the line impedance caused by the grid-connected current. During this process, the system has already begun voltage ride-through and generating reactive current; therefore, there is a phase difference between the sampled grid voltage and the actual grid voltage.

[0047] At the moment the grid voltage recovers, the phase difference between the grid-connected current and the actual grid voltage causes the grid-connected current to be in the wrong direction, which may cause the system to experience energy backflow, ultimately leading to bus overvoltage protection.

[0048] To address the aforementioned problems, this invention proposes a control method for a charging and discharging module, detailed below.

[0049] See Figure 2 The diagram illustrates a flowchart of the control method for a charging / discharging module provided in an embodiment of the present invention. The entity executing the control method for the charging / discharging module can be a control device, which may be a controller.

[0050] See Figure 2 The control method for the above-mentioned charging and discharging module includes:

[0051] In S201, when the charging and discharging module is in a low voltage ride-through state, it acquires the instantaneous voltage values ​​of each phase of the power grid.

[0052] When the grid voltage drops to a certain level, the charging and discharging module enters the low voltage ride-through process. At this time, the charging and discharging module can be considered to be in the low voltage ride-through state.

[0053] Specifically, the system can determine whether the charging / discharging module is in a low-voltage ride-through state based on the grid voltage. For example, the charging / discharging module is considered to be in a low-voltage ride-through state when the grid voltage drop percentage is less than a preset percentage, or when the grid voltage is within a preset low-voltage ride-through voltage range, or when the grid voltage is less than a preset low-voltage ride-through voltage threshold; otherwise, the charging / discharging module is considered not to be in a low-voltage ride-through state. The preset percentage, preset low-voltage ride-through voltage range, and preset low-voltage ride-through voltage threshold can all be set according to actual needs and are not specifically limited here.

[0054] A special case of low-voltage ride-through is zero-voltage ride-through. During low-voltage ride-through, the grid voltage continuously drops; when it drops to an even lower level, it is considered to have entered zero-voltage ride-through. This embodiment determines when the zero-voltage ride-through process begins by acquiring the instantaneous voltage values ​​of each phase of the grid.

[0055] The instantaneous value of the voltage of each phase of the power grid can be the instantaneous value of the phase voltage of each phase of the power grid, or it can be the instantaneous value of the line voltage between each phase of the power grid. For example, the instantaneous value of the voltage of each phase of the power grid can be the instantaneous value of the phase voltage of phase A, the instantaneous value of the phase voltage of phase B, and the instantaneous value of the phase voltage of phase C; it can also be the instantaneous value of the line voltage between phase A and phase B, the instantaneous value of the line voltage between phase B and phase C, and the instantaneous value of the line voltage between phase C and phase A.

[0056] This embodiment does not limit the specific means of obtaining the instantaneous voltage values ​​of each phase of the power grid.

[0057] In S202, if the instantaneous voltage values ​​of each phase of the power grid are detected to meet the preset zero-voltage ride-through condition, the phase-locked loop is controlled to stop working.

[0058] The phase-locked loop (PLL) is used to lock the grid voltage during operation and to stop locking the grid voltage when the operation stops. The preset zero-voltage ride-through condition includes the maximum instantaneous value of the voltage of each phase of the grid being less than the preset voltage value, and the duration for which the maximum instantaneous value of the voltage of each phase of the grid is less than the preset voltage value being greater than the preset duration.

[0059] In this embodiment, when the instantaneous voltage values ​​of each phase of the power grid meet the preset zero voltage ride-through conditions, the charging and discharging module is considered to be in a zero voltage ride-through state and is in the process of zero voltage ride-through. At this time, the phase-locked loop is not operated to ensure that the phase-locked loop can exit quickly and will not cause the grid voltage to be missampled due to the grid current, which would ultimately cause the phase output phase of the phase-locked loop to deviate from the actual grid voltage phase.

[0060] When a phase-locked loop (PLL) is working, it can lock onto the real-time grid voltage and output the real-time phase of the grid voltage. When the PLL stops working, it stops locking onto the real-time grid voltage, meaning it no longer outputs the real-time phase of the grid voltage. However, when the PLL stops working, it doesn't completely stop outputting a signal; rather, the output signal remains the same as the signal at the moment before it stopped working. In other words, when the PLL stops working, the output phase is the phase of the grid voltage at the moment before it stopped working.

[0061] The preset zero-voltage ride-through condition includes the following: the maximum instantaneous voltage value of each phase of the power grid is less than the preset voltage value, and the duration for which the maximum instantaneous voltage value of each phase of the power grid is less than the preset voltage value is greater than the preset duration. The maximum instantaneous voltage value of each phase of the power grid refers to the maximum of the instantaneous line voltages between phases A and B, between phases B and C, and between phases C and A. The preset voltage value and preset duration can be set according to actual needs, such as considering actual power outages and the effectiveness of low-voltage ride-through; no specific restrictions are imposed here.

[0062] This embodiment does not change the loop parameters of the phase-locked loop, but only changes the conditions under which the phase-locked loop does not work, so that the system can perform zero-voltage ride-through normally.

[0063] This embodiment determines that the charging / discharging module has entered the zero-voltage ride-through state when the charging / discharging module is in a low-voltage ride-through state, and the maximum instantaneous voltage value of each phase of the power grid is less than a preset voltage value, and the duration for which the maximum instantaneous voltage value of each phase of the power grid is less than the preset voltage value is greater than a preset duration. At this time, the phase-locked loop (PLL) is controlled to stop working to ensure that the PLL can exit quickly. This ensures that when the power grid voltage recovers, the PLL output signal and the actual power grid voltage will no longer have a phase difference, and there will be no bus overvoltage protection. The zero-voltage ride-through process can be completed normally, improving the stability of the charging / discharging module.

[0064] In some embodiments, prior to S201, the control method for the charging and discharging module further includes:

[0065] Obtain the percentage drop in grid voltage;

[0066] If the percentage drop in grid voltage is less than a preset percentage, the charge / discharge module is controlled to enter a low-voltage ride-through state.

[0067] The preset percentage can be set according to actual needs, such as determining it based on the actual power outage situation of the grid voltage. For example, the preset percentage can be 90%.

[0068] In this embodiment, when the percentage drop in grid voltage is less than a preset percentage, the charging and discharging module is controlled to enter a low voltage ride-through state, which can reduce the number of repeated grid connection attempts and reduce the impact on the grid.

[0069] In some embodiments, the control of the charge / discharge module to enter a low-voltage ride-through state includes:

[0070] The control module outputs reactive grid-connected current; the phase of the reactive grid-connected current is the same as the phase of the output signal of the phase-locked loop.

[0071] In this embodiment, when the percentage drop in grid voltage is less than a preset percentage, a low-voltage ride-through process is initiated. The charging and discharging module is then controlled to output reactive grid-connected current to the grid for grid connection. Specifically, this can involve controlling the V2G machine to output reactive grid-connected current to the grid. The magnitude of the reactive grid-connected current can be determined based on actual needs, such as referenced standards, and is not specifically limited here.

[0072] The phase of the reactive grid-connected current is the same as the phase of the output signal of the phase-locked loop (PLL), specifically, it is the same as the phase of the sin value of the line voltage output by the PLL.

[0073] In some embodiments, obtaining the percentage drop in grid voltage as described above includes:

[0074] Obtain the instantaneous values ​​of the three-phase power grid voltage;

[0075] Transform the instantaneous values ​​of the three-phase grid voltage from the ABC coordinate system to the DQ0 coordinate system to obtain the D-axis component values ​​of the grid voltage;

[0076] The percentage drop in grid voltage is obtained based on the D-axis component of the grid voltage and the rated grid voltage.

[0077] Percentage voltage drop of mains voltage = D-axis component of mains voltage / Rated mains voltage /

[0078] In some embodiments, after the phase-locked loop stops operating, the control method for the charging and discharging module further includes:

[0079] When the instantaneous voltage values ​​of each phase of the power grid are detected to no longer meet the preset zero-voltage ride-through condition, the phase-locked loop (PLL) restarts operation.

[0080] In this embodiment, when the phase-locked loop stops working, if it is detected that the instantaneous value of the voltage of each phase of the power grid no longer meets the preset zero voltage ride-through condition, the phase-locked loop is controlled to start working again, that is, the phase-locked loop is controlled to start locking the real-time power grid voltage again and output the real-time phase of the power grid voltage.

[0081] In this embodiment, the phase-locked loop (PLL) is controlled to stop working only when the instantaneous voltage values ​​of each phase of the power grid meet the preset zero-voltage ride-through condition. In other cases, the PLL is controlled to work.

[0082] In some embodiments, the process of determining the preset voltage value and the preset duration includes:

[0083] The phase difference between the phase of the phase-locked loop output signal and the actual phase of the grid voltage is obtained during the time from the actual power outage to the detection of the power outage.

[0084] When the phase difference is less than the preset phase difference value, the preset voltage value and preset duration are determined.

[0085] In this embodiment, power outages can be detected using software or hardware. However, there is a time difference between the actual power outage and the detected outage. During this time, the phase difference between the output signal of the phase-locked loop (PLL) and the actual phase of the grid voltage must not be too large, i.e., it must be less than a preset phase difference value. If this phase difference is too large, it can easily lead to bus overvoltage protection issues when the grid voltage recovers. Based on this condition, the preset voltage value and preset time duration can be determined through relevant experiments.

[0086] For example, when the instantaneous value of the voltage of each phase of the power grid is the instantaneous value of the line voltage between each phase of the power grid, the preset voltage value can be 50V and the preset duration can be 2ms; when the instantaneous value of the voltage of each phase of the power grid is the instantaneous value of the phase voltage of each phase of the power grid, the preset voltage value can be... The preset duration can be 2ms.

[0087] The preset phase difference value can be determined based on the results of the zero-voltage ride-through experiment, and no specific restrictions are imposed here.

[0088] In a specific application scenario, see Figure 3 The control method for the above-mentioned charging and discharging module may include:

[0089] Detect the percentage drop in mains voltage;

[0090] If the voltage drop percentage of the grid is less than 90%, then reactive grid current is output, and the low voltage ride-through process begins.

[0091] The system detects whether the maximum instantaneous voltage of each phase of the power grid is less than 50V and lasts for 2ms. If so, the phase-locked loop (PLL) is deactivated; otherwise, the PLL continues to operate.

[0092] A zero-voltage ride-through experiment was conducted using the control method of the charge / discharge module provided in this embodiment of the invention, and the system variables were rippled, as shown in the waveform. Figure 4As shown, after the grid voltage recovers, the sin value output by the phase-locked loop no longer has a phase difference with the actual grid voltage, so the system can complete the zero-voltage ride-through process normally.

[0093] This invention provides a detailed analysis of the problem of bus overvoltage protection causing system ride-through failure during zero-voltage ride-through of the charging and discharging module. Based on the cause of the problem, a new solution is proposed, enabling the system to perform zero-voltage ride-through stably and reliably. The solution is simple and practical, does not consume excessive resources, and can be used as a reference for other projects.

[0094] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0095] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0096] Figure 5 A schematic diagram of the control device for the charging and discharging module provided in an embodiment of the present invention is shown. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below:

[0097] like Figure 5 As shown, the control device 30 of the charging and discharging module includes: an acquisition module 31 and a first control module 32.

[0098] The acquisition module 31 is used to acquire the instantaneous voltage values ​​of each phase of the power grid when the charging and discharging module is in a low voltage ride-through state.

[0099] The first control module 32 is used to control the phase-locked loop to stop working if the instantaneous value of the voltage of each phase of the power grid is detected to meet the preset zero voltage ride-through condition.

[0100] The phase-locked loop (PLL) is used to lock the grid voltage during operation and to stop locking the grid voltage when the operation stops. The preset zero-voltage ride-through condition includes the maximum instantaneous value of the voltage of each phase of the grid being less than the preset voltage value, and the duration for which the maximum instantaneous value of the voltage of each phase of the grid is less than the preset voltage value being greater than the preset duration.

[0101] In one possible implementation, the control device for the charging and discharging module further includes a second control module.

[0102] The second control module is used to obtain the percentage drop in grid voltage; if the percentage drop in grid voltage is less than a preset percentage, the charging and discharging module is controlled to enter the low voltage ride-through state.

[0103] In one possible implementation, the second control module is specifically used for:

[0104] The control module outputs reactive grid-connected current; the phase of the reactive grid-connected current is the same as the phase of the output signal of the phase-locked loop.

[0105] In one possible implementation, the second control module is specifically used for:

[0106] Obtain the instantaneous values ​​of the three-phase power grid voltage;

[0107] Transform the instantaneous values ​​of the three-phase grid voltage from the ABC coordinate system to the DQ0 coordinate system to obtain the D-axis component values ​​of the grid voltage;

[0108] The percentage drop in grid voltage is obtained based on the D-axis component of the grid voltage and the rated grid voltage.

[0109] In one possible implementation, the control device for the charging and discharging module further includes a third control module.

[0110] The third control module is used to restart the phase-locked loop (PLL) after it has stopped working, when it detects that the instantaneous voltage values ​​of each phase of the power grid no longer meet the preset zero-voltage ride-through condition.

[0111] In one possible implementation, the process of determining the preset voltage value and the preset duration includes:

[0112] The phase difference between the phase of the phase-locked loop output signal and the actual phase of the grid voltage is obtained during the time from the actual power outage to the detection of the power outage.

[0113] When the phase difference is less than the preset phase difference value, the preset voltage value and preset duration are determined.

[0114] Figure 6 This is a schematic diagram of the control device provided in an embodiment of the present invention. Figure 6 As shown, the control device 4 in this embodiment includes a processor 40 and a memory 41. The memory 41 stores a computer program 42, and the processor 40 calls and runs the computer program 42 stored in the memory 41 to execute the steps in the control method embodiments of the various charging and discharging modules described above, for example... Figure 2 S201 to S202 are shown. Alternatively, the processor 40 is used to call and run the computer program 42 stored in the memory 41 to implement the functions of each module / unit in the above-described device embodiments, for example... Figure 5 The functions of modules / units 31 to 32 shown.

[0115] For example, the computer program 42 can be divided into one or more modules / units, which are stored in the memory 41 and executed by the processor 40 to complete the present invention. The one or more modules / units can be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program 42 in the control device 4. For example, the computer program 42 can be divided into... Figure 5 Modules / units 31 to 32 are shown.

[0116] The control device 4 can be a controller, or a computing device such as a desktop computer, laptop, handheld computer, or cloud server. The control device 4 may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art will understand that... Figure 6 This is merely an example of control device 4 and does not constitute a limitation on control device 4. It may include more or fewer components than shown, or combine certain components, or different components. For example, the control device may also include input / output devices, network access devices, buses, etc.

[0117] The processor 40 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0118] The memory 41 can be an internal storage unit of the control device 4, such as a hard disk or memory of the control device 4. The memory 41 can also be an external storage device of the control device 4, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card equipped on the control device 4. Furthermore, the memory 41 can include both internal and external storage units of the control device 4. The memory 41 is used to store the computer program and other programs and data required by the control device. The memory 41 can also be used to temporarily store data that has been output or will be output.

[0119] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0120] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0121] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0122] In the embodiments provided by this invention, it should be understood that the disclosed apparatus / control devices and methods can be implemented in other ways. For example, the apparatus / control device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0123] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0124] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0125] If the integrated module / unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the control method embodiments for each of the above charging and discharging modules. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0126] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A control method for a charging and discharging module, characterized in that, The control method for the charging and discharging module includes: When the charging and discharging module is in a low voltage ride-through state, it acquires the instantaneous voltage values ​​of each phase of the power grid. If the instantaneous voltage values ​​of each phase of the power grid are detected to meet the preset zero-voltage ride-through condition, the phase-locked loop is controlled to stop working. The phase-locked loop is used to lock the grid voltage during operation and to stop locking the grid voltage when the operation stops, while maintaining the phase of the grid voltage at the moment before the operation stops. The preset zero voltage ride-through condition includes the maximum instantaneous value of the voltage of each phase of the grid being less than a preset voltage value, and the duration for which the maximum instantaneous value of the voltage of each phase of the grid is less than the preset voltage value being greater than a preset duration. After the phase-locked loop stops working, the method further includes: when it is detected that the instantaneous value of the voltage of each phase of the power grid no longer meets the preset zero-voltage ride-through condition, controlling the phase-locked loop to start working again.

2. The control method for the charging and discharging module according to claim 1, characterized in that, Before acquiring the instantaneous voltage values ​​of each phase of the power grid when the charging / discharging module is in a low-voltage ride-through state, the control method for the charging / discharging module further includes: Obtain the percentage drop in grid voltage; If the percentage drop in the grid voltage is less than a preset percentage, the charging and discharging module is controlled to enter a low voltage ride-through state.

3. The control method for the charging and discharging module according to claim 2, characterized in that, The control of the charge / discharge module to enter the low-voltage ride-through state includes: The charging and discharging module is controlled to output reactive grid-connected current; the phase of the reactive grid-connected current is the same as the phase of the output signal of the phase-locked loop.

4. The control method for the charging and discharging module according to claim 2, characterized in that, The acquisition of the percentage drop in grid voltage includes: Obtain the instantaneous values ​​of the three-phase power grid voltage; The instantaneous values ​​of the three-phase grid voltage are transformed from the ABC coordinate system to the DQ0 coordinate system to obtain the D-axis component values ​​of the grid voltage. The percentage drop in grid voltage is obtained based on the D-axis component value of the grid voltage and the rated grid voltage value.

5. The control method for the charging and discharging module according to any one of claims 1 to 4, characterized in that, The process of determining the preset voltage value and the preset duration includes: The phase difference between the phase of the output signal of the phase-locked loop and the actual phase of the grid voltage is obtained during the time from the actual power outage to the detection of the power outage. When the phase difference is less than a preset phase difference value, the preset voltage value and the preset duration are determined.

6. A control device for a charging and discharging module, characterized in that, The control device for the charging and discharging module includes: The acquisition module is used to acquire the instantaneous voltage values ​​of each phase of the power grid when the charging and discharging module is in a low voltage ride-through state. The first control module is used to control the phase-locked loop to stop working if the instantaneous value of the voltage of each phase of the power grid is detected to meet the preset zero voltage ride-through condition. The phase-locked loop is used to lock the grid voltage during operation and to stop locking the grid voltage when the operation stops, while maintaining the phase of the grid voltage at the moment before the operation stops. The preset zero voltage ride-through condition includes the maximum instantaneous value of the voltage of each phase of the grid being less than a preset voltage value, and the duration for which the maximum instantaneous value of the voltage of each phase of the grid is less than the preset voltage value being greater than a preset duration. The third control module is used to restart the phase-locked loop (PLL) after it has stopped working, when it detects that the instantaneous voltage values ​​of each phase of the power grid no longer meet the preset zero-voltage ride-through condition.

7. The control device for the charging and discharging module according to claim 6, characterized in that, The control device for the charging and discharging module also includes: The second control module is used to obtain the percentage drop in grid voltage; if the percentage drop in grid voltage is less than a preset percentage, the charging and discharging module is controlled to enter the low voltage ride-through state.

8. A control device, characterized in that, It includes a processor and a memory, the memory being used to store computer programs, and the processor being used to call and run the computer programs stored in the memory to execute the control method of the charging and discharging module as described in any one of claims 1 to 5.

9. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the steps of the control method for the charging and discharging module as described in any one of claims 1 to 5.

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