Power distribution network long distance end low voltage treatment method and system

Abstract

The application provides a power distribution network long-distance end low-voltage treatment method and system, which comprises the following steps: obtaining the difference and shortage power of a line, and judging whether the difference and shortage power is greater than a first preset threshold; if the difference and shortage power is greater than the first preset threshold, judging whether the difference and shortage power is greater than a photovoltaic real-time power; if the difference and shortage power is less than or equal to the photovoltaic real-time power, executing a first preset control strategy; if the difference and shortage power is greater than the photovoltaic real-time power, judging whether the photovoltaic real-time power is equal to a second preset threshold; if the photovoltaic real-time power is equal to the second preset threshold, judging whether the battery capacity is greater than a third preset threshold; if the battery capacity is greater than the third preset threshold, executing a second preset control strategy; if the battery capacity is less than or equal to the third preset threshold, executing a third preset control strategy. The application can treat the low-voltage problem of the line in real time and accurately.

Description

Technical Field

[0001] This invention relates to the field of low voltage management technology, and in particular to a method and system for managing low voltage at long-distance terminals of a power distribution network. Background Technology

[0002] In existing low-voltage distribution networks (400V / 220V), there are a large number of users located 800-2500 meters away from transformers. Due to the excessive transmission distance and significant voltage loss, the voltage at the user end is only around 130-180V, and even lower during peak periods (120V or lower), affecting their normal electricity consumption. These users are referred to as "low-voltage users" in the power grid system. With the improvement of people's living standards and the widespread use of electrical appliances in rural areas, the demand has shifted from low-power applications such as lighting and television to diverse high-power applications such as electric cooking appliances, electric farm implements, water heaters, and air conditioners. Therefore, with rapid economic development, the phenomenon of low voltage is also increasing, and the problem is becoming increasingly prominent.

[0003] In summary, existing long-distance terminal lines often face low voltage problems due to their long transmission distances and dispersed loads. This problem not only affects users' normal power supply but may also lead to equipment damage and energy waste. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for managing low voltage at long-distance ends of a power distribution network, aiming to solve the low voltage problem at long-distance ends of lines caused by long transmission distances and dispersed loads in traditional technologies.

[0005] In a first aspect, the present invention provides a method for mitigating low voltage at long-distance ends of a distribution network, applied to a photovoltaic-storage-charging superimposed frequency conversion device, the method comprising:

[0006] Obtain the differential power of the line and determine whether the differential power is greater than a first preset threshold.

[0007] If the deficit power is greater than the first preset threshold, then determine whether the deficit power is greater than the real-time photovoltaic power.

[0008] If the deficit power is less than or equal to the real-time photovoltaic power, then the first preset control strategy is executed;

[0009] If the power deficit is greater than the real-time photovoltaic power, then determine whether the real-time photovoltaic power is equal to the second preset threshold.

[0010] If the real-time photovoltaic power is equal to the second preset threshold, then determine whether the battery capacity is greater than the third preset threshold.

[0011] If the battery capacity is greater than the third preset threshold, then the second preset control strategy will be executed.

[0012] If the battery capacity is less than or equal to the third preset threshold, the third preset control strategy will be executed.

[0013] Furthermore, the step of obtaining the differential power of the line includes:

[0014] Each cycle is sampled according to a preset sampling rate, and the difference voltage value at the current moment is obtained based on the sampling results and the theoretical objective function corresponding to the cycle.

[0015] Obtain the transient load of the line at the current moment, and calculate the differential power based on the differential voltage value and the transient load.

[0016] Furthermore, after the step of determining whether the real-time photovoltaic power is equal to the second preset threshold if the power deficit is greater than the real-time photovoltaic power, the method further includes:

[0017] If the real-time photovoltaic power is not equal to the second preset threshold, then the fourth preset control strategy is executed.

[0018] Furthermore, after the step of obtaining the differential power of the line and determining whether the differential power is greater than the first preset threshold, the method further includes:

[0019] If the power deficit is equal to the first preset threshold, then determine whether the real-time photovoltaic power is greater than the third preset threshold.

[0020] If the real-time photovoltaic power is greater than the third preset threshold, then determine whether the real-time photovoltaic power is greater than the battery discharge power.

[0021] If the real-time photovoltaic power is greater than the battery discharge power, then determine whether the battery capacity is greater than the fourth preset threshold and less than the fifth preset threshold.

[0022] If the battery capacity is greater than the fourth preset threshold and less than the fifth preset threshold, then the fifth preset control strategy will be executed.

[0023] If the battery capacity is greater than or equal to the fifth preset threshold, then the sixth preset control strategy will be executed.

[0024] Furthermore, after the step of determining whether the real-time photovoltaic power is greater than the battery discharge power, the method further includes:

[0025] If the real-time photovoltaic power is less than the battery discharge power, then determine whether the battery capacity is less than or equal to the fourth preset threshold.

[0026] If the battery capacity is less than or equal to the fourth preset threshold, the seventh preset control strategy will be executed.

[0027] Furthermore, the step of determining whether the real-time photovoltaic power is greater than a third preset threshold if the power deficit is equal to a first preset threshold also includes:

[0028] If the real-time photovoltaic power is less than or equal to the third preset threshold, then determine whether the battery capacity is less than or equal to the fourth preset threshold.

[0029] If the battery capacity is less than or equal to the fourth preset threshold, the eighth preset control strategy will be executed.

[0030] Furthermore, the first preset control strategy is: to switch to the photovoltaic channel to utilize photovoltaic energy to achieve waveform superposition, so that... ;

[0031] The second preset control strategy is: switch to the battery channel, so that... ;

[0032] The third preset control strategy is to limit the output power of the battery channel so that... , ,at this time ;

[0033] The fourth preset control strategy is to switch to a hybrid battery and photovoltaic channel to enable... ;

[0034] The fifth preset control strategy is to switch the photovoltaic power to the charging channel and the inverter grid-connected channel respectively, so that... , ;

[0035] The sixth preset control strategy is to disconnect the photovoltaic power from the charging channel, so that P bi =0, and the photovoltaic grid connection channel makes ;

[0036] The seventh preset control strategy is to switch all photovoltaic power to the charging channel, so that... ;

[0037] The eighth preset control strategy is: to switch the mains power to the charging channel and control the charging power so that the charging power matches the voltage of the mains input line. ;

[0038] in, Indicates the power deficit. Indicates the compensation power. Indicates real-time photovoltaic power. Indicates battery charging power. Indicates the battery discharge power. Indicates battery capacity, Indicates the starting compensation voltage. This indicates that the compensation voltage has been stopped. This indicates the user's voltage.

[0039] Furthermore, the method also includes:

[0040] After executing the corresponding control strategy, the instantaneous voltage value of the next cycle is obtained, and the new transient load is calculated based on the instantaneous voltage value and the difference voltage value of the previous cycle.

[0041] Repeated sampling is performed to obtain the differential voltage value for the next cycle. Based on the differential voltage value and the new transient load, the differential power for the next cycle is calculated. The line is then monitored and controlled cyclically based on the differential power for the next cycle.

[0042] Furthermore, the difference power is obtained according to the following formula:

[0043] ;

[0044] The new transient load is obtained using the following formula:

[0045] ;

[0046] in, Indicates the instantaneous voltage value. Indicates the differential voltage value. Indicates the instantaneous current value. This indicates a new transient load.

[0047] Secondly, the present invention provides a low-voltage management system for long-distance distribution network terminals, applied to a photovoltaic-storage-charging superimposed frequency conversion device, the system comprising:

[0048] The first differential power detection module is used to acquire the differential power of the line and determine whether the differential power is greater than the first preset threshold.

[0049] The second defect power detection module is used to determine whether the defect power is greater than the real-time photovoltaic power if the defect power is greater than the first preset threshold.

[0050] The first control module is used to execute a first preset control strategy if the deficit power is less than or equal to the real-time photovoltaic power.

[0051] The first photovoltaic power detection module is used to determine whether the real-time photovoltaic power is equal to a second preset threshold if the defective power is greater than the real-time photovoltaic power.

[0052] The first battery capacity detection module is used to determine whether the battery capacity is greater than the third preset threshold if the real-time photovoltaic power is equal to the second preset threshold.

[0053] The second control module is used to execute the second preset control strategy if the battery capacity is greater than the third preset threshold.

[0054] The third control module is used to execute the third preset control strategy if the battery capacity is less than or equal to the third preset threshold.

[0055] Thirdly, the present invention provides a storage medium that stores one or more programs, which, when executed by a processor, implement the above-described method for managing low voltage at long-distance ends of a power distribution network.

[0056] Fourthly, the present invention provides an electronic device, the electronic device comprising a memory and a processor, wherein:

[0057] The memory is used to store computer programs;

[0058] When the processor executes the computer program stored in the memory, it implements the above-mentioned method for managing low voltage at long-distance ends of the power distribution network.

[0059] Compared with the prior art, the embodiments of the present invention have the following advantages:

[0060] This invention acquires the differential power of the power line and dynamically selects an appropriate control strategy based on the magnitude of the differential power and parameters such as real-time photovoltaic power and battery capacity. It fully leverages the combined advantages of photovoltaic energy and battery energy storage, flexibly switching between photovoltaic channels, battery channels, or a hybrid channel for compensation based on parameters such as real-time photovoltaic power and battery capacity. This method enables real-time and precise management of low-voltage problems, effectively avoiding the slow response and limited compensation effects of traditional methods, while simultaneously improving energy utilization. Attached Figure Description

[0061] Figure 1 This is a flowchart of a method for managing low voltage at long-distance ends of a distribution network according to an embodiment of the present invention;

[0062] Figure 2 This is a detailed diagram of step S101 according to an embodiment of the present invention;

[0063] Figure 3 This is a schematic diagram of a long-distance low-voltage management system for power distribution networks proposed in an embodiment of the present invention.

[0064] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0065] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.

[0066] like Figure 1 As shown, an embodiment of the present invention provides a method for managing low voltage at long-distance ends of a distribution network. This method is applied to a photovoltaic-storage-charging superimposed frequency device. The method includes steps S01 to S07, wherein:

[0067] Step S01: Obtain the differential power of the line and determine whether the differential power is greater than the first preset threshold.

[0068] It should be noted that in some embodiments, in order to accurately obtain the difference power, it is necessary to sample each cycle according to a preset sampling rate, and obtain the difference voltage value at the current moment according to the sampling results and the theoretical objective function corresponding to the cycle.

[0069] Obtain the transient load of the line at the current moment, and calculate the differential power based on the differential voltage value and the transient load.

[0070] For example, first, the instantaneous line current and voltage values ​​at the current moment are read, and the current transient load can be calculated. Then, 128 voltage points are sampled for each cycle at a sampling rate of 6.4KHz. The sampling results are compared with the theoretical objective function. By calculating the difference between the coaxial time component values, the differential voltage value of the line at the current time point can be obtained. Then, the differential power can be obtained according to the following formula:

[0071] .

[0072] Then, with S as a constant, the closed-loop gain is used to output a PWM modulation waveform as the input to the DSP2 objective function, with a modulation period of... , This enables power compensation for the difference in power at that point.

[0073] Step S02: If the deficit power is greater than the first preset threshold, then determine whether the deficit power is greater than the real-time photovoltaic power.

[0074] In addition, if the power deficit is equal to the first preset threshold, it is determined whether the real-time photovoltaic power is greater than the third preset threshold.

[0075] If the real-time photovoltaic power is greater than the third preset threshold, then determine whether the real-time photovoltaic power is greater than the battery discharge power.

[0076] If the real-time photovoltaic power is greater than the battery discharge power, then determine whether the battery capacity is greater than the fourth preset threshold and less than the fifth preset threshold.

[0077] If the battery capacity is greater than the fourth preset threshold and less than the fifth preset threshold, then the fifth preset control strategy will be executed.

[0078] If the battery capacity is greater than or equal to the fifth preset threshold, then the sixth preset control strategy will be executed.

[0079] In addition, if the real-time photovoltaic power is less than the battery discharge power, it is determined whether the battery capacity is less than or equal to the fourth preset threshold.

[0080] If the battery capacity is less than or equal to the fourth preset threshold, the seventh preset control strategy will be executed.

[0081] Step S03: If the deficit power is less than or equal to the real-time photovoltaic power, then execute the first preset control strategy;

[0082] Step S04: If the power deficit is greater than the real-time photovoltaic power, then determine whether the real-time photovoltaic power is equal to the second preset threshold.

[0083] Step S05: If the real-time photovoltaic power is equal to the second preset threshold, then determine whether the battery capacity is greater than the third preset threshold;

[0084] Furthermore, if the real-time photovoltaic power is not equal to the second preset threshold, then the fourth preset control strategy is executed.

[0085] Step S06: If the battery capacity is greater than the third preset threshold, then execute the second preset control strategy;

[0086] In addition, if the real-time photovoltaic power is less than or equal to the third preset threshold, it is determined whether the battery capacity is less than or equal to the fourth preset threshold.

[0087] If the battery capacity is less than or equal to the fourth preset threshold, the eighth preset control strategy will be executed.

[0088] Step S07: If the battery capacity is less than or equal to the third preset threshold, then execute the third preset control strategy.

[0089] Specifically, in some embodiments, the first preset control strategy is: switching to the photovoltaic channel to utilize photovoltaic energy to achieve waveform superposition, so that... ;

[0090] The second preset control strategy is: switch to the battery channel, so that... ;

[0091] The third preset control strategy is to limit the output power of the battery channel so that... , ,at this time ;

[0092] The fourth preset control strategy is to switch to a hybrid battery and photovoltaic channel to enable... ;

[0093] The fifth preset control strategy is to switch the photovoltaic power to the charging channel and the inverter grid-connected channel respectively, so that... , ;

[0094] The sixth preset control strategy is to disconnect the photovoltaic power from the charging channel, so that... Furthermore, the photovoltaic grid connection channel enables... ;

[0095] The seventh preset control strategy is to switch all photovoltaic power to the charging channel, so that... ;

[0096] The eighth preset control strategy is: to switch the mains power to the charging channel and control the charging power so that the charging power matches the voltage of the mains input line. ;

[0097] in, Indicates the power deficit. Indicates the compensation power. Indicates real-time photovoltaic power. Indicates battery charging power. Indicates the battery discharge power. Indicates battery capacity, Indicates the starting compensation voltage. This indicates that the compensation voltage has been stopped. This indicates the user's voltage.

[0098] For example, such as Figure 2 As shown, DSP2 monitors and controls the photovoltaic, battery, and mains power supply, with each of the three connected in pairs, and executes the following control logic:

[0099] I. When When this happens, the following control policies will be implemented:

[0100] (1) If This indicates that photovoltaic power generation is sufficient. DSP2 will control the mains power to switch to the photovoltaic channel, using photovoltaic energy to achieve waveform superposition, so that the photovoltaic array can compensate for the mains power. At the same time, the remaining power of the photovoltaic array will be supplied to the battery side, thereby enabling... .

[0101] (2) If ,and If the value is not zero, it indicates that relying solely on the real-time power of the photovoltaic array to compensate for the power deficit is insufficient. To maximize the compensation for the power deficit, DSP2 will control the mains power to switch to a hybrid channel of battery and photovoltaic power, enabling both the battery side and the photovoltaic array to simultaneously compensate for the mains power, thus achieving... .

[0102] (3) If ,and This indicates that the battery capacity is sufficient. DSP2 will control the mains power to switch to the battery channel to compensate for the power deficiency through the battery, thereby achieving... .

[0103] (4) If ,and This indicates a low mains voltage situation, and the photovoltaic system is not generating electricity at this time, i.e., it occurs at night. Simultaneously, the battery's own charge capacity is insufficient. Based on this, two concepts are defined: start-up compensation voltage and stop-compensation voltage. First, DSP2 will limit the output power of the battery channel. At the same time, In order to achieve .

[0104] II. When ,and Execute the following logic:

[0105] (5) If , This indicates that there is no low voltage issue with the mains power, but the battery has insufficient charge capacity. In this situation, DSP2 will switch all the photovoltaic power from the photovoltaic array to the charging channel, allowing the photovoltaic array to charge the battery. .

[0106] (6) , This indicates that the real-time photovoltaic power is greater than the battery charging power and the battery's charge capacity is sufficient. At this point, DSP2 switches the photovoltaic real-time power to both the charging channel and the inverter grid-connected channel. That is, on the one hand, the photovoltaic array charges the battery; on the other hand, to avoid energy waste, the photovoltaic array compensates for the mains power through the inverter grid-connected channel. , However, since no compensation is actually needed at this time, the power grid will have a floating voltage. When the floating voltage is within the stop compensation voltage, DSP2 will continue to execute this control strategy. When the floating voltage exceeds the stop compensation voltage, the excess part will be used to perform a light-wasting operation through PWM chopping.

[0107] (7) , This indicates that the battery's charge capacity is full, and the photovoltaic array cannot charge it. At this point, DSP2 disconnects the photovoltaic power from the charging channel. Simultaneously, the photovoltaic array will be connected to the inverter grid-connected channel to compensate for the power of the mains power. Similarly, the portion exceeding the stop compensation voltage will be subject to chopping and light rejection.

[0108] III. When ,and Execute the following logic:

[0109] (8) This indicates it is nighttime and the battery may be in a state of insufficient charge capacity. In this case, DSP2 will control the mains power to switch to the charging channel and simultaneously control the charging power to ensure that the charging power matches the voltage of the mains input. .

[0110] The DSP1 monitors the mains input voltage and feeds it back to the DSP2 to achieve closed-loop dynamic control.

[0111] Furthermore, in some embodiments, the light-wasting operation is specifically described as follows:

[0112] By performing time integration on the compensation power W using DSP1, the total watt-hours injected into the grid by the equipment can be obtained. The overall efficiency of discharge and inverter is calculated as 96%;

[0113] The charging power is controlled by DSP1 By performing time integration calculations, the total watt-hours of electricity charged can be obtained. The charging conversion efficiency is calculated at 95%.

[0114] The total watt-hours of self-consumption can be obtained by DSP1 performing time integral calculations on the device's own power consumption. ;

[0115] Therefore, the initial value of the line loss T0 is: ;

[0116] Then, the photovoltaic input power PV during the same period is integrated and calculated. When the condition is met... Under certain conditions, triggering the light-wasting operation will achieve the setpoint line loss compensation of zero for this device. If degraded line loss compensation is required, then the following conditions must be met: The difference greater than is the value that needs to be reduced.

[0117] Furthermore, in some embodiments, after executing the corresponding control strategy, the instantaneous voltage value of the next cycle is obtained, and a new transient load is calculated based on the instantaneous voltage value and the differential voltage value of the previous cycle; sampling is repeated to obtain the differential voltage value of the next cycle, and the differential power of the next cycle is calculated based on the differential voltage value of the next cycle and the new transient load; the line is then cyclically monitored and controlled based on the differential power of the next cycle. Specifically, the new transient load is obtained according to the following formula:

[0118] ;

[0119] in, Indicates the instantaneous voltage value. Indicates the differential voltage value. Indicates the instantaneous current value. This indicates a new transient load; subtracting the difference voltage value from the previous cycle from the instantaneous voltage value is to avoid triggering circuit self-oscillation.

[0120] For example, in a periodic Repeat the above capture process to perform cyclical detection and control operation. This completes the compensation for the entire sine wave cycle.

[0121] In summary, the above-described method for managing low voltage at long-distance distribution network terminals acquires the differential power of the line and dynamically selects appropriate control strategies based on the magnitude of the differential power, real-time photovoltaic power, and battery capacity. It fully leverages the combined advantages of photovoltaic energy and battery storage, flexibly switching between photovoltaic channels, battery channels, or a hybrid channel for compensation based on parameters such as real-time photovoltaic power and battery capacity. This method enables real-time and precise management of low voltage issues, effectively avoiding the slow response and limited compensation effects of traditional methods, while simultaneously improving energy utilization.

[0122] like Figure 3 As shown, one embodiment of the present invention also provides a low-voltage management system for long-distance distribution network terminals, applied to a photovoltaic-storage-charging superimposed frequency conversion device, the system comprising:

[0123] The first differential power detection module 10 is used to acquire the differential power of the line and determine whether the differential power is greater than the first preset threshold.

[0124] The second defect power detection module 20 is used to determine whether the defect power is greater than the real-time photovoltaic power if the defect power is greater than the first preset threshold.

[0125] The first control module 30 is used to execute a first preset control strategy if the deficit power is less than or equal to the real-time photovoltaic power.

[0126] The first photovoltaic power detection module 40 is used to determine whether the real-time photovoltaic power is equal to a second preset threshold if the defective power is greater than the real-time photovoltaic power.

[0127] The first battery capacity detection module 50 is used to determine whether the battery capacity is greater than the third preset threshold if the real-time photovoltaic power is equal to the second preset threshold.

[0128] The second control module 60 is used to execute the second preset control strategy if the battery capacity is greater than the third preset threshold.

[0129] The third control module 70 is used to execute a third preset control strategy if the battery capacity is less than or equal to a third preset threshold.

[0130] In addition, in some embodiments, the system further includes:

[0131] The fourth control module is used to execute a fourth preset control strategy if the real-time photovoltaic power is not equal to the second preset threshold.

[0132] In addition, in some embodiments, the system further includes:

[0133] The third defect power detection module is used to determine whether the real-time photovoltaic power is greater than the third preset threshold if the defect power is equal to the first preset threshold.

[0134] The second photovoltaic power detection module is used to determine whether the real-time photovoltaic power is greater than the battery discharge power if the real-time photovoltaic power is greater than the third preset threshold.

[0135] The second battery capacity detection module is used to determine whether the battery capacity is greater than the fourth preset threshold and less than the fifth preset threshold if the real-time photovoltaic power is greater than the battery discharge power.

[0136] The fifth control module is used to execute the fifth preset control strategy if the battery capacity is greater than the fourth preset threshold and less than the fifth preset threshold.

[0137] The sixth control module is used to execute the sixth preset control strategy if the battery capacity is greater than or equal to the fifth preset threshold.

[0138] In addition, in some embodiments, the system further includes:

[0139] The third battery capacity detection module is used to determine whether the battery capacity is less than or equal to the fourth preset threshold if the real-time photovoltaic power is less than the battery discharge power.

[0140] The seventh control module is used to execute the seventh preset control strategy if the battery capacity is less than or equal to the fourth preset threshold.

[0141] In addition, in some embodiments, the system further includes:

[0142] The fourth battery capacity detection module is used to determine whether the battery capacity is less than or equal to the fourth preset threshold if the real-time photovoltaic power is less than or equal to the third preset threshold.

[0143] The eighth control module is used to execute the eighth preset control strategy if the battery capacity is less than or equal to the fourth preset threshold.

[0144] In addition, in some embodiments, the system further includes:

[0145] The transient load calculation module is used to obtain the instantaneous voltage value of the next cycle after executing the corresponding control strategy, and calculate the new transient load based on the instantaneous voltage value and the difference voltage value of the previous cycle.

[0146] The resampling module is used to repeatedly sample to obtain the differential voltage value of the next cycle, calculate the differential power of the next cycle based on the differential voltage value of the next cycle and the new transient load, and perform cyclic monitoring and control of the line based on the differential power of the next cycle.

[0147] In another aspect, the present invention also proposes a storage medium on which one or more programs are stored, which, when executed by a processor, implement the above-described method for managing low voltage at long-distance ends of a power distribution network.

[0148] In another aspect, the present invention also proposes an electronic device, including a memory and a processor, wherein the memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory to implement the above-mentioned method for managing low voltage at long-distance ends of the power distribution network.

[0149] Those skilled in the art will understand that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can mean any means that can contain stored, communicated, propagated, or transmitted programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0150] More specific examples of computer-readable media (a non-exhaustive list) include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which the program can be printed, because the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0151] It should be understood that various parts of the present invention can be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0152] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A method for managing low voltage at long-distance ends of a distribution network, applied to a photovoltaic-storage-charging superimposed frequency conversion device, characterized in that, The method includes: Obtain the differential power of the line and determine whether the differential power is greater than a first preset threshold. Each cycle is sampled according to a preset sampling rate, and the difference voltage value at the current moment is obtained based on the sampling results and the theoretical objective function corresponding to the cycle. Obtain the transient load of the line at the current moment, and calculate the differential power based on the differential voltage value and the transient load; If the deficit power is greater than the first preset threshold, then determine whether the deficit power is greater than the real-time photovoltaic power. If the power deficit is equal to the first preset threshold, then determine whether the real-time photovoltaic power is greater than the third preset threshold. If the real-time photovoltaic power is greater than the third preset threshold, then determine whether the real-time photovoltaic power is greater than the battery discharge power. If the real-time photovoltaic power is greater than the battery discharge power, then determine whether the battery capacity is greater than the fourth preset threshold and less than the fifth preset threshold. If the battery capacity is greater than the fourth preset threshold and less than the fifth preset threshold, then the fifth preset control strategy will be executed. If the battery capacity is greater than or equal to the fifth preset threshold, then the sixth preset control strategy will be executed. If the real-time photovoltaic power is less than the battery discharge power, then determine whether the battery capacity is less than or equal to the fourth preset threshold. If the battery capacity is less than or equal to the fourth preset threshold, then the seventh preset control strategy will be executed. If the real-time photovoltaic power is less than or equal to the third preset threshold, then determine whether the battery capacity is less than or equal to the fourth preset threshold. If the battery capacity is less than or equal to the fourth preset threshold, then the eighth preset control strategy is executed. If the deficit power is less than or equal to the real-time photovoltaic power, then the first preset control strategy is executed; If the power deficit is greater than the real-time photovoltaic power, then determine whether the real-time photovoltaic power is equal to the second preset threshold. If the real-time photovoltaic power is equal to the second preset threshold, then determine whether the battery capacity is greater than the third preset threshold. If the real-time photovoltaic power is not equal to the second preset threshold, then the fourth preset control strategy is executed; If the battery capacity is greater than the third preset threshold, then the second preset control strategy will be executed. If the battery capacity is less than or equal to the third preset threshold, the third preset control strategy will be executed. The first preset control strategy is to switch to the photovoltaic channel to utilize photovoltaic energy to achieve waveform superposition, thereby enabling... ; The second preset control strategy is: switch to the battery channel, so that... ; The third preset control strategy is to limit the output power of the battery channel so that... , ,at this time ; The fourth preset control strategy is to switch to a hybrid battery and photovoltaic channel to enable... ; The fifth preset control strategy is to switch the photovoltaic power to the charging channel and the inverter grid-connected channel respectively, so that... , ; The sixth preset control strategy is to disconnect the photovoltaic power from the charging channel, so that... Furthermore, the photovoltaic grid connection channel enables... ; The seventh preset control strategy is to switch all photovoltaic power to the charging channel, so that... ; The eighth preset control strategy is: to switch the mains power to the charging channel and control the charging power so that the charging power matches the voltage of the mains input line. ; in, Indicates the power deficit. Indicates the compensation power. Indicates real-time photovoltaic power. Indicates battery charging power. Indicates the battery discharge power. Indicates battery capacity, Indicates the starting compensation voltage. This indicates that the compensation voltage has been stopped. This indicates the user's voltage.

2. The method for managing low voltage at long-distance ends of a distribution network according to claim 1, characterized in that, The method further includes: After executing the corresponding control strategy, the instantaneous voltage value of the next cycle is obtained, and the new transient load is calculated based on the instantaneous voltage value and the difference voltage value of the previous cycle. Repeated sampling is performed to obtain the differential voltage value for the next cycle. Based on the differential voltage value and the new transient load, the differential power for the next cycle is calculated. The line is then monitored and controlled cyclically based on the differential power for the next cycle.

3. The method for managing low voltage at long-distance ends of a distribution network according to claim 2, characterized in that, The power difference can be obtained using the following formula: ； The new transient load is obtained using the following formula: ； in, Indicates the instantaneous voltage value. Indicates the differential voltage value. Indicates the instantaneous current value. This indicates a new transient load.

4. A low-voltage management system for long-distance distribution network terminals, applied to a photovoltaic-storage-charging superimposed frequency conversion device, characterized in that, The system includes: The first differential power detection module is used to acquire the differential power of the line and determine whether the differential power is greater than the first preset threshold. Each cycle is sampled according to a preset sampling rate, and the difference voltage value at the current moment is obtained based on the sampling results and the theoretical objective function corresponding to the cycle. Obtain the transient load of the line at the current moment, and calculate the differential power based on the differential voltage value and the transient load; The second power deficiency detection module is used to determine whether the power deficiency is greater than the real-time photovoltaic power if the power deficiency is greater than the first preset threshold. If the power deficit is equal to the first preset threshold, then determine whether the real-time photovoltaic power is greater than the third preset threshold. If the real-time photovoltaic power is greater than the third preset threshold, then determine whether the real-time photovoltaic power is greater than the battery discharge power. If the real-time photovoltaic power is greater than the battery discharge power, then determine whether the battery capacity is greater than the fourth preset threshold and less than the fifth preset threshold. If the battery capacity is greater than the fourth preset threshold and less than the fifth preset threshold, then the fifth preset control strategy will be executed. If the battery capacity is greater than or equal to the fifth preset threshold, then the sixth preset control strategy will be executed. If the real-time photovoltaic power is less than the battery discharge power, then determine whether the battery capacity is less than or equal to the fourth preset threshold. If the battery capacity is less than or equal to the fourth preset threshold, then the seventh preset control strategy will be executed. If the real-time photovoltaic power is less than or equal to the third preset threshold, then determine whether the battery capacity is less than or equal to the fourth preset threshold. If the battery capacity is less than or equal to the fourth preset threshold, then the eighth preset control strategy is executed. The first control module is used to execute a first preset control strategy if the deficit power is less than or equal to the real-time photovoltaic power. The first photovoltaic power detection module is used to determine whether the real-time photovoltaic power is equal to a second preset threshold if the defective power is greater than the real-time photovoltaic power. The first battery capacity detection module is used to determine whether the battery capacity is greater than the third preset threshold if the real-time photovoltaic power is equal to the second preset threshold. If the real-time photovoltaic power is not equal to the second preset threshold, then the fourth preset control strategy is executed; The second control module is used to execute the second preset control strategy if the battery capacity is greater than the third preset threshold. The third control module is used to execute the third preset control strategy if the battery capacity is less than or equal to the third preset threshold. The first preset control strategy is to switch to the photovoltaic channel to utilize photovoltaic energy to achieve waveform superposition, thereby enabling... ; The second preset control strategy is: switch to the battery channel, so that... ; The third preset control strategy is to limit the output power of the battery channel so that... , ,at this time ; The fourth preset control strategy is to switch to a hybrid battery and photovoltaic channel to enable... ; The fifth preset control strategy is to switch the photovoltaic power to the charging channel and the inverter grid-connected channel respectively, so that... , ; The sixth preset control strategy is to disconnect the photovoltaic power from the charging channel, so that... Furthermore, the photovoltaic grid connection channel enables... ; The seventh preset control strategy is to switch all photovoltaic power to the charging channel, so that... ; The eighth preset control strategy is: to switch the mains power to the charging channel and control the charging power so that the charging power matches the voltage of the mains input line. ; in, Indicates the power deficit. Indicates the compensation power. Indicates real-time photovoltaic power. Indicates battery charging power. Indicates the battery discharge power. Indicates battery capacity, Indicates the starting compensation voltage. This indicates that the compensation voltage has been stopped. This indicates the user's voltage.

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