Photovoltaic power generation MPPT cooperative control method related to fault ride-through and related device
Patent Information
- Application Number
- CN202510478064.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-16
- Publication Date
- 2025-07-04
Smart Images
Figure CN120262541A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of photovoltaic power generation, and particularly to a coordinated control method and related device for photovoltaic power generation MPPT with fault ride-through. Background Art
[0002] The current energy structure is accelerating its transformation towards cleaner energy, and the impact of high-proportion new energy grid connection on the safe and stable operation of the power system is becoming increasingly prominent. For a photovoltaic power generation system, during a grid voltage dip fault, if appropriate energy dissipation or power control strategies are not adopted in a timely manner for control and mitigation, it is very easy to occur an imbalance in active power between the AC and DC sides, resulting in overvoltage and overcurrent of equipment and even triggering disconnection protection, which not only causes regional power supply interruption, but also exacerbates the grid transient impact and prolongs the fault recovery time.
[0003] The prior art usually configures a dynamic energy dissipation device inside a photovoltaic power generation unit or at the substation side to quickly absorb the surplus power output by the photovoltaic power generation system in the event of a fault. Although this method can solve the problem of fault ride-through of the photovoltaic power generation unit during a grid voltage fault, the required capacity of the energy-consuming device is large, which will increase the equipment cost and space occupation. Summary of the Invention
[0004] This application provides a coordinated control method and related device for photovoltaic power generation MPPT with fault ride-through, which is used to solve the technical problems that the prior art is time-consuming and laborious in the way of installing a large number of energy-consuming devices in a photovoltaic power generation system and will occupy a large installation space.
[0005] In view of this, the first aspect of this application provides a coordinated control method for photovoltaic power generation MPPT with fault ride-through, including:
[0006] S1: When the AC grid-connected voltage is normal, if the AC grid-connected voltage continuously remains less than the fluctuation threshold within a preset abnormal time period, set the voltage status identifier to fault 1 and latch the photovoltaic array port voltage as the first latch voltage;
[0007] S2: When the AC grid-connected voltage is faulty, if the AC grid-connected voltage continuously remains greater than the fluctuation threshold within a preset normal time period, set the voltage status identifier to normal 0 and use the second latch voltage stored in the latch as the initial voltage for MPPT calculation;
[0008] S3: If the voltage status identifier is normal 0, the DC voltage command of the converter is obtained through MPPT calculation based on the initial voltage. If the voltage status identifier is fault 1, the DC voltage command of the converter is calculated according to the first latch voltage and the photovoltaic open-circuit voltage.
[0009] Preferably, before step S1, it further includes:
[0010] Judge the voltage status identifier during the operation of the photovoltaic power generation grid-connected system in real time;
[0011] If the voltage status identifier is normal 0, it is determined that the AC grid-connected voltage is in a normal state. If the voltage status identifier is a fault 1, it is determined that the AC grid-connected voltage is in a fault state.
[0012] Preferably, it further includes:
[0013] If the AC grid-connected voltage does not meet the condition of "continuously less than the fluctuation threshold within the preset abnormal time period" or "continuously greater than the fluctuation threshold within the preset normal time period", the operation of step S3 is executed.
[0014] Preferably, step S3 includes:
[0015] If the voltage status identifier is normal 0, perform MPPT calculation based on the initial voltage to obtain the port voltage command of the photovoltaic array, and use the port voltage command as the DC voltage command of the converter;
[0016] If the voltage status identifier is a fault 1, calculate the first increment according to the first latch voltage and the photovoltaic open-circuit voltage, and at the same time calculate the second increment according to the first latch voltage, the photovoltaic open-circuit voltage, the voltage dip depth and the preset amplification factor;
[0017] If the first increment is greater than or equal to the second increment, use the second increment as the converter command increment. Otherwise, use the first increment as the converter command increment;
[0018] Sum the converter command increment and the first latch voltage to obtain the DC voltage command of the converter.
[0019] The second aspect of the present application provides a first state change unit, which is used to, when the AC grid-connected voltage is normal, if the AC grid-connected voltage continuously is less than the fluctuation threshold within the preset abnormal time period, set the voltage status identifier to a fault 1 and latch the photovoltaic array port voltage as the first latch voltage;
[0020] A second state change unit, which is used to, when the AC grid-connected voltage is faulty, if the AC grid-connected voltage continuously is greater than the fluctuation threshold within the preset normal time period, set the voltage status identifier to normal 0 and use the second latch voltage stored in the latch as the initial voltage for MPPT calculation;
[0021] The MPPT analysis and control unit is used to calculate the MPPT of the converter DC voltage command based on the initial voltage if the voltage status identifier is normal 0, and calculate the converter DC voltage command according to the first latch voltage and the PV open-circuit voltage if the voltage status identifier is faulty 1.
[0022] Preferably, it further includes a real-time status monitoring unit, specifically used for:
[0023] Judging the voltage status identifier during the operation of the photovoltaic power generation grid-connected system in real time;
[0024] If the voltage status identifier is normal 0, it is determined that the AC grid-connected voltage is in a normal state, and if the voltage status identifier is faulty 1, it is determined that the AC grid-connected voltage is in a faulty state.
[0025] Preferably, it further includes:
[0026] The state stability unit is used to trigger the operation of the MPPT analysis and control unit if the AC grid-connected voltage does not meet the condition of "continuously less than the fluctuation threshold within the preset abnormal time period" or "continuously greater than the fluctuation threshold within the preset normal time period".
[0027] Preferably, the MPPT analysis and control unit is specifically used for:
[0028] If the voltage status identifier is normal 0, perform MPPT calculation according to the initial voltage to obtain the port voltage command of the photovoltaic array, and use the port voltage command as the converter DC voltage command;
[0029] If the voltage status identifier is faulty 1, calculate the first increment according to the first latch voltage and the PV open-circuit voltage, and calculate the second increment according to the first latch voltage, the PV open-circuit voltage, the voltage dip depth and the preset amplification factor;
[0030] If the first increment is greater than or equal to the second increment, use the second increment as the converter command increment, otherwise use the first increment as the converter command increment;
[0031] Sum the converter command increment and the first latch voltage to obtain the converter DC voltage command.
[0032] The third aspect of the present application provides a photovoltaic power generation MPPT cooperative control device related to fault ride-through, and the device includes a processor and a memory;
[0033] The memory is used to store program codes and transmit the program codes to the processor;
[0034] The processor is configured to execute the photovoltaic power generation MPPT cooperative control method involving fault ride-through according to the instructions in the program code as described in the first aspect.
[0035] A fourth aspect of the present application provides a computer-readable storage medium, which is configured to store program code for executing the photovoltaic power generation MPPT cooperative control method involving fault ride-through as described in the first aspect.
[0036] It can be seen from the above technical solutions that the embodiments of the present application have the following advantages:
[0037] In the present application, a photovoltaic power generation MPPT cooperative control method involving fault ride-through is provided, including: S1: When the AC grid-connected voltage is normal, if the AC grid-connected voltage continuously remains less than the fluctuation threshold within a preset abnormal time period, set the voltage status identifier to fault 1 and latch the photovoltaic array port voltage as the first latch voltage; S2: When the AC grid-connected voltage fails, if the AC grid-connected voltage continuously remains greater than the fluctuation threshold within a preset normal time period, set the voltage status identifier to normal 0 and use the second latch voltage stored in the latch as the initial voltage for MPPT calculation; S3: If the voltage status identifier is normal 0, the converter DC voltage command is obtained by performing MPPT calculation based on the initial voltage. If the voltage status identifier is fault 1, the converter DC voltage command is calculated according to the first latch voltage and the photovoltaic open-circuit voltage.
[0038] The photovoltaic power generation MPPT cooperative control method involving fault ride-through provided by the present application can effectively reduce the output active power of the photovoltaic grid-connected system during an AC grid fault, so there is no need to rely on a large number of energy-consuming devices for a long time for energy consumption; by comprehensively analyzing the operating state of the AC grid and adopting corresponding MPPT cooperative control strategies, it can not only meet the normal control requirements of the photovoltaic power generation system, but also achieve fault ride-through cooperative control under fault conditions to ensure the stability of the system. This process includes the determination and analysis of the AC grid-connected voltage status. Based on different control strategies, converter DC voltage commands corresponding to different working conditions are generated according to different technical requirements when transitioning from the normal state to the fault state and from the fault state to the normal state, realizing stable and reliable MPPT control and fault ride-through cooperative control, and avoiding problems such as overvoltage and overcurrent caused by the imbalance of active power on the AC and DC sides of the converter under fault conditions. Therefore, the present application can solve the technical problems that the existing technology is time-consuming and laborious in installing a large number of energy-consuming devices in the photovoltaic power generation system and will occupy a large installation space. BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Figure 1 It is a flowchart of the photovoltaic power generation MPPT cooperative control method involving fault ride-through provided by the embodiments of the present application;
[0040] Figure 2 Schematic diagram of the structure of the photovoltaic power generation MPPT collaborative control device involving fault ride-through provided by the embodiment of the present application;
[0041] Figure 3 Schematic diagram of the structure of the photovoltaic power generation grid-connected system provided by the embodiment of the present application;
[0042] Figure 4 Example diagram of the overall process of the photovoltaic power generation MPPT collaborative control involving fault ride-through provided by the embodiment of the present application. Specific implementation manners
[0043] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.
[0044] For ease of understanding, please refer to Figure 1 , the embodiments of the photovoltaic power generation MPPT collaborative control method involving fault ride-through provided by the present application include:
[0045] The photovoltaic power generation MPPT collaborative control method of this embodiment is applied to a photovoltaic power generation grid-connected system as shown in Figure 3 . This system mainly includes photovoltaic modules, a busbar line, MPPT (Maximum Power Point Tracking), an inverter and its control, etc. Among them, the inverter can adopt either a single-pole or a two-stage structure; the photovoltaic array is composed of components connected in series and components connected in parallel. , are respectively the port voltage and port current of the photovoltaic array, is the DC voltage command of the inverter, and is the AC grid-connected voltage of the photovoltaic inverter; and here is the per-unit value.
[0046] In addition, represents the depth of voltage dip of the AC grid-connected voltage of the photovoltaic inverter; denote as the normal fluctuation value of the AC grid-connected voltage, which can take a value of 5%, and the fluctuation threshold used in the specific determination and analysis is denoted as ; and other used, for example, the preset abnormal time period is denoted as , and the preset normal time period is denoted as ; It is denoted as the voltage status identifier.
[0047] Step 101: When the AC grid-connected voltage is normal, if the AC grid-connected voltage continuously falls below the fluctuation threshold within a preset abnormal time period, set the voltage status identifier to Fault 1, and latch the photovoltaic array port voltage as the first latch voltage.
[0048] Further, before step 101, it also includes:
[0049] Judge the voltage status identifier during the operation of the photovoltaic power generation grid-connected system in real time;
[0050] If the voltage status identifier is Normal 0, it is determined that the AC grid-connected voltage is in a normal state. If the voltage status identifier is Fault 1, it is determined that the AC grid-connected voltage is in a fault state.
[0051] Judge and analyze the value of the voltage status identifier during the operation of the photovoltaic power generation grid-connected system in real time. If , it means that the previous AC grid-connected voltage was normal, and perform the operation of step 101; if , it means that the previous AC grid-connected voltage was faulty, and perform the operation of step 102.
[0052] When the voltage status identifier is Normal 0, that is, when the previous AC grid-connected voltage was in a normal state, analyze whether the AC grid-connected voltage continuously falls below the fluctuation threshold within a preset abnormal time period . If so, it means that the current AC grid-connected voltage has failed, indicating that the AC grid-connected voltage has changed from a normal state to a fault state. At this time, the value of the voltage status identifier needs to be set to 1, and the photovoltaic array port voltage is latched as the first latch voltage, that is, the MPP voltage before the fault is latched in the latch and denoted as the first latch voltage ; if not, it means that the current AC grid voltage status has not changed, that is, it is still in a normal state, so the values of the voltage status identifier , the first latch voltage are not changed, which is equivalent to no operation action in the actual execution program.
[0053] It should be noted that it is crucial that the voltage dip duration meets the preset abnormal time period . If the AC grid-connected voltage has a short-term dip but is not enough to reach the preset abnormal time , the operation of reassigning values will not be triggered. That is, if the AC grid-connected voltage drops for a duration less than the preset abnormal time period , the voltage status identifier is not set to fault 1. This sets a fluctuation compatibility time for the system to avoid immediately determining an abnormality once a voltage fluctuation occurs, which may lead to misjudgment and affect the stable operation of the system.
[0054] It should be noted that this step is used to determine the transition of the AC grid voltage from the normal state to the fault state and save the voltage at the PV array port at the moment before the fault occurs for subsequent use.
[0055] Step 102: In the case of an AC grid connection voltage fault, if the AC grid connection voltage continuously exceeds the fluctuation threshold within a preset normal time period, the voltage status identifier is set to normal 0, and the second latch voltage stored in the latch is used as the initial voltage for MPPT calculation.
[0056] When the voltage status identifier is fault 1, that is, when the previous AC grid connection voltage was in the fault state, analyze the AC grid connection voltage whether it continuously exceeds the fluctuation threshold within a preset normal time period . If so, it indicates that the current AC grid connection voltage has returned to normal and is within the normal voltage fluctuation range of the grid, meaning that the AC grid connection voltage has recovered from the fault state to the normal state. At this time, the value of the voltage status identifier should be set to 0, and the second latch voltage previously stored in the latch is used as the initial voltage for MPPT calculation; if not, it indicates that the current AC grid voltage status has not changed, that is, it is still in the fault state, so the value of the voltage status identifier is not changed and the initial voltage for MPPT calculation is not set, which is equivalent to no operation in the actual execution program.
[0057] Similarly, the duration of the voltage rise meeting the preset normal time is crucial. If the AC grid connection voltage experiences a short-term increase but is not sufficient to reach the preset abnormal time , the operation of reassigning values will not be triggered. That is, if the AC grid connection voltage recovers for a duration less than the preset normal time , the voltage status identifier is not set to normal 0. This sets a fluctuation compatibility time for the system to avoid immediately determining normality once a voltage increase occurs, which may lead to misjudgment and affect the stable operation of the system.
[0058] It should be noted that this step is used to determine the recovery of the AC grid voltage from the fault state to the normal state and set the initial voltage for MPPT calculation after the fault recovery based on the voltage at the PV array port at the moment before the fault, so as to reduce the time consumed for re-scanning to the MPP after the fault recovery and improve the MPP tracking speed.
[0059] Step 103: If the voltage status identifier is normal 0, the converter DC voltage command is obtained based on the initial voltage through MPPT calculation; if the voltage status identifier is faulty 1, the converter DC voltage command is calculated according to the first latch voltage and the PV open-circuit voltage.
[0060] Further, step 103 includes:
[0061] If the voltage status identifier is normal 0, perform MPPT calculation according to the initial voltage to obtain the port voltage command of the PV array, and use the port voltage command as the converter DC voltage command;
[0062] If the voltage status identifier is faulty 1, calculate the first increment according to the first latch voltage and the PV open-circuit voltage, and at the same time calculate the second increment according to the first latch voltage, the PV open-circuit voltage, the voltage dip depth, and the preset amplification factor;
[0063] If the first increment is greater than or equal to the second increment, use the second increment as the converter command increment; otherwise, use the first increment as the converter command increment;
[0064] Sum the converter command increment and the first latch voltage to obtain the converter DC voltage command.
[0065] It should be noted that if the voltage status identifier is normal 0, that is, the current AC grid-connected voltage is in a normal state, the converter DC voltage command calculation under normal conditions needs to be performed, that is, perform MPPT calculation according to the initial voltage to obtain the port voltage command of the PV array and use the port voltage command as the converter DC voltage command. .
[0066] If the voltage status identifier is faulty 1, that is, the current AC grid-connected voltage is in a faulty state, the converter DC voltage command calculation under faulty conditions needs to be performed. The converter DC voltage command calculation under faulty conditions includes operations such as increment calculation, increment comparison and limiting, and summation.
[0067] Trigger limiting calculation:
[0068] First, calculate the first increment according to the first latch voltage and the PV open-circuit voltage :
[0069]
[0070] Among them, is the open-circuit voltage of a single PV module, that is, the PV open-circuit voltage, is the first latch voltage, is the number of series-connected PV modules.
[0071] Then, calculate the second increment according to the first latch voltage, the open-circuit voltage of the photovoltaic cell, the depth of voltage dip, and a preset amplification factor. :
[0072]
[0073] Wherein, is the depth of voltage dip of the AC grid-connected voltage, is the preset amplification factor, , and The larger it is, the more the active power output of the photovoltaic array decreases during the fault.
[0074] Next, compare the magnitudes of the first increment and the second increment . If , then use the second increment as the converter command increment ; if , then use the first increment as the converter command increment . It can be found that the comparison and limiting process is to ensure that the obtained converter command increment definitely does not exceed the first increment , achieving the purpose of limiting.
[0075] Finally, sum the converter command increment and the first latch voltage to obtain the converter DC voltage command , specifically expressed as: .
[0076] It should be noted that the function of this step is to select the corresponding control strategy according to the current state of the AC grid-connected voltage.
[0077] Furthermore, it further includes:
[0078] If the AC grid-connected voltage does not meet the conditions of "continuously less than the fluctuation threshold within a preset abnormal time period" or "continuously greater than the fluctuation threshold within a preset normal time period", then perform the operation of step 103. This means that regardless of whether step 101 or step 102 has been executed before, step 103 can be entered.
[0079] Please refer to Figure 4 . In both step 101 and step 102, there is a process of analyzing the continuous state of the AC grid-connected voltage, that is, determining whether the AC grid-connected voltage exceeds the fluctuation threshold within a preset time period. Both step 101 and step 102 are execution processes that meet these two conditions. In another embodiment, there may be a situation where this determination condition is not met, that is, one of them does not meet the condition.
[0080] If the AC grid-connected voltage does not meet the condition of "continuously less than the fluctuation threshold within the preset abnormal time period" or "continuously greater than the fluctuation threshold within the preset normal time period", whether the duration does not reach the time condition or the voltage does not exceed the fluctuation threshold, both belong to the above-mentioned non-compliant situations. Then there is no substantial operation in step 101 or step 102, and it can directly enter the determination in step 103. Therefore, this operation process is directly described as entering the determination operation in step 103 if one of these conditions is not met.
[0081] The photovoltaic power generation MPPT cooperative control method involving fault ride-through provided by this application can effectively reduce the output active power of the photovoltaic grid-connected system during the AC grid fault. Therefore, it does not need to rely on a large number of energy-consuming devices for a long time; by comprehensively analyzing the operating state of the AC grid and adopting the corresponding MPPT cooperative control strategy, it can not only meet the normal control requirements of the photovoltaic power generation system, but also achieve fault ride-through cooperative control under fault conditions to ensure the stability of the system. This process includes the determination and analysis of the state of the AC grid-connected voltage. According to different technical requirements when changing from the normal state to the fault state and from the fault state to the normal state, based on different control strategies, the DC voltage command of the converter under the corresponding working conditions is generated to achieve stable and reliable MPPT control and fault ride-through cooperative control, and avoid problems such as overvoltage and overcurrent caused by the imbalance of active power on the AC and DC sides of the converter under fault conditions. Therefore, this application can solve the technical problems of the prior art that the method of installing a large number of energy-consuming devices in the photovoltaic power generation system is time-consuming and laborious and will occupy a large installation space.
[0082] For ease of understanding, please refer to Figure 2 , this application provides an embodiment of a photovoltaic power generation MPPT cooperative control device involving fault ride-through, including:
[0083] The first state change unit 201 is used to, when the AC grid-connected voltage is normal, if the AC grid-connected voltage continuously is less than the fluctuation threshold within the preset abnormal time period, set the voltage state identifier to fault 1, and latch the photovoltaic array port voltage as the first latch voltage;
[0084] The second state change unit 202 is used to, when the AC grid-connected voltage is faulty, if the AC grid-connected voltage continuously is greater than the fluctuation threshold within the preset normal time period, set the voltage state identifier to normal 0, and use the second latch voltage stored in the latch as the initial voltage for MPPT calculation;
[0085] The MPPT analysis and control unit 203 is used to, if the voltage state identifier is normal 0, calculate the DC voltage command of the converter based on the initial voltage through MPPT calculation, and if the voltage state identifier is fault 1, calculate the DC voltage command of the converter according to the first latch voltage and the photovoltaic open-circuit voltage.
[0086] Further, it further includes a real-time status monitoring unit 204, which is specifically used for:
[0087] Judging the voltage status identifier during the operation of the photovoltaic power generation grid-connected system in real time;
[0088] If the voltage status identifier is normal 0, it is determined that the AC grid-connected voltage is in a normal state. If the voltage status identifier is a fault 1, it is determined that the AC grid-connected voltage is in a fault state.
[0089] Further, it further includes:
[0090] A state stability unit 205, which is used to trigger the operation of the MPPT analysis and control unit if the AC grid-connected voltage does not meet the condition of "continuously less than the fluctuation threshold within a preset abnormal time period" or "continuously greater than the fluctuation threshold within a preset normal time period".
[0091] Further, the MPPT analysis and control unit 203 is specifically used for:
[0092] If the voltage status identifier is normal 0, perform MPPT calculation according to the initial voltage to obtain the port voltage command of the photovoltaic array, and use the port voltage command as the DC voltage command of the converter;
[0093] If the voltage status identifier is a fault 1, calculate the first increment according to the first latch voltage and the photovoltaic open-circuit voltage, and at the same time calculate the second increment according to the first latch voltage, the photovoltaic open-circuit voltage, the voltage dip depth, and a preset amplification factor;
[0094] If the first increment is greater than or equal to the second increment, use the second increment as the converter command increment. Otherwise, use the first increment as the converter command increment;
[0095] Sum the converter command increment and the first latch voltage to obtain the DC voltage command of the converter.
[0096] This application also provides a photovoltaic power generation MPPT cooperative control device involving fault ride-through. The device includes a processor and a memory;
[0097] The memory is used to store program codes and transmit the program codes to the processor;
[0098] The processor is used to execute the photovoltaic power generation MPPT cooperative control method involving fault ride-through in the above method embodiments according to the instructions in the program codes.
[0099] This application also provides a computer-readable storage medium. The computer-readable storage medium is used to store program codes, and the program codes are used to execute the photovoltaic power generation MPPT cooperative control method involving fault ride-through in the above method embodiments.
[0100] In several embodiments provided by the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.
[0101] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place, or they can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.
[0102] In addition, in each embodiment of the present application, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.
[0103] If the above-mentioned integrated unit is implemented in the form of 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, the technical solution of the present application, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present application. And the aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (English full name: Read-Only Memory, English abbreviation: ROM), random access memories (English full name: Random Access Memory, English abbreviation: RAM), magnetic disks or optical discs that can store program codes.
[0104] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting it; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present application.
Claims
1. A photovoltaic power generation MPPT cooperative control method involving fault ride-through, characterized in that Including: S1: When the AC grid-connected voltage is normal, if the AC grid-connected voltage continuously remains less than the fluctuation threshold within a preset abnormal time period, set the voltage status identifier to fault 1, and latch the photovoltaic array port voltage as the first latch voltage; S2: When the AC grid-connected voltage fails, if the AC grid-connected voltage continuously remains greater than the fluctuation threshold within a preset normal time period, set the voltage status identifier to normal 0, and use the second latch voltage stored in the latch as the initial voltage for MPPT calculation; S3: If the voltage status identifier is normal 0, the converter DC voltage command is obtained through MPPT calculation based on the initial voltage. If the voltage status identifier is fault 1, the converter DC voltage command is calculated according to the first latch voltage and the photovoltaic open-circuit voltage.
2. The photovoltaic power generation MPPT cooperative control method involving fault ride-through according to claim 1, characterized in that Before step S1, it further includes: Real-time judgment is made on the voltage status identifier during the operation of the photovoltaic power generation grid-connected system; If the voltage status identifier is normal 0, it is determined that the AC grid-connected voltage is in a normal state. If the voltage status identifier is fault 1, it is determined that the AC grid-connected voltage is in a fault state.
3. The photovoltaic power generation MPPT cooperative control method involving fault ride-through according to claim 1, wherein It further includes: If the AC grid-connected voltage does not meet the condition of "continuously remaining less than the fluctuation threshold within a preset abnormal time period" or "continuously remaining greater than the fluctuation threshold within a preset normal time period", perform the operation of step S3.
4. The photovoltaic power generation MPPT collaborative control method involving fault ride-through according to claim 1, wherein Step S3 includes: If the voltage status identifier is normal 0, perform MPPT calculation based on the initial voltage to obtain the port voltage command of the photovoltaic array, and use the port voltage command as the converter DC voltage command; If the voltage status identifier is fault 1, calculate the first increment according to the first latch voltage and the photovoltaic open-circuit voltage, and at the same time calculate the second increment according to the first latch voltage, the photovoltaic open-circuit voltage, the voltage dip depth, and a preset amplification factor; If the first increment is greater than or equal to the second increment, use the second increment as the converter command increment. Otherwise, use the first increment as the converter command increment; Sum the converter command increment and the first latch voltage to obtain the converter DC voltage command.
5. The photovoltaic power generation MPPT collaborative control device related to fault ride-through is characterized in that, Including: The first state change unit is used to, when the AC grid-connected voltage is normal, if the AC grid-connected voltage continuously remains less than the fluctuation threshold within a preset abnormal time period, set the voltage status identifier to fault 1, and latch the photovoltaic array port voltage as the first latch voltage; The second state change unit is used to, when the AC grid-connected voltage fails, if the AC grid-connected voltage continuously remains greater than the fluctuation threshold within a preset normal time period, set the voltage status identifier to normal 0, and use the second latch voltage stored in the latch as the initial voltage for MPPT calculation; The MPPT analysis and control unit is configured to, if the voltage status identifier is normal 0, calculate the converter DC voltage command based on the initial voltage through MPPT calculation; if the voltage status identifier is fault 1, calculate the converter DC voltage command according to the first latch voltage and the PV open-circuit voltage.
6. The photovoltaic power generation MPPT collaborative control device involving fault ride-through according to claim 5, characterized in that, It further includes a real-time status monitoring unit, which is specifically configured to: Make a real-time judgment on the voltage status identifier during the operation of the photovoltaic power generation and grid-connected system; If the voltage status identifier is normal 0, it is determined that the AC grid-connected voltage is in a normal state; if the voltage status identifier is fault 1, it is determined that the AC grid-connected voltage is in a fault state.
7. The photovoltaic power generation MPPT cooperative control device involving fault ride-through according to claim 5, characterized in that, It further includes: The status stability unit is configured to, if the AC grid-connected voltage does not meet the condition of "continuously less than the fluctuation threshold within the preset abnormal time period" or "continuously greater than the fluctuation threshold within the preset normal time period", trigger the operation of the MPPT analysis and control unit.
8. The photovoltaic power generation MPPT cooperative control device involving fault ride-through according to claim 5, characterized in that, The MPPT analysis and control unit is specifically configured to: If the voltage status identifier is normal 0, perform MPPT calculation according to the initial voltage to obtain the port voltage command of the photovoltaic array, and use the port voltage command as the converter DC voltage command; If the voltage status identifier is fault 1, calculate the first increment according to the first latch voltage and the PV open-circuit voltage, and at the same time calculate the second increment according to the first latch voltage, the PV open-circuit voltage, the voltage dip depth, and the preset amplification factor; If the first increment is greater than or equal to the second increment, use the second increment as the converter command increment; otherwise, use the first increment as the converter command increment; Sum the converter command increment and the first latch voltage to obtain the converter DC voltage command.
9. The photovoltaic power generation MPPT cooperative control device involving fault ride-through is characterized in that The device includes a processor and a memory; The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the photovoltaic power generation MPPT collaborative control method involving fault ride-through according to any one of claims 1-4 based on the instructions in the program codes.
10. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store program codes, and the program codes are used to execute the photovoltaic power generation MPPT collaborative control method involving fault ride-through according to any one of claims 1-4.