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

Abstract

The invention provides a long-distance tail end low-voltage treatment method and system for a power distribution network, and the method comprises the steps: obtaining the differential power of a line, and judging whether the differential power is greater than a first preset threshold value or not; if the differential power is larger than a first preset threshold value, whether the differential power is larger than photovoltaic real-time power or not is judged; if the difference lacking power is smaller than or equal to the photovoltaic real-time power, executing a first preset control strategy; if the difference lacking power is greater than the photovoltaic real-time power, judging whether the photovoltaic real-time power is equal to a second preset threshold value or not; if the photovoltaic real-time power is equal to a second preset threshold value, whether the battery capacity is larger than a third preset threshold value or not is judged; if the battery capacity is greater than a third preset threshold value, executing a second preset control strategy; and if the battery capacity is smaller than or equal to a third preset threshold value, executing a third preset control strategy. According to the invention, the low-voltage problem of the line can be accurately treated in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of low - voltage management, and particularly to a method and system for managing low voltage at the long - distance end of a distribution network. Background Art

[0002] In the existing low - voltage distribution network (400V / 220V), there are a large number of users whose distance from the transformer is 800 - 2500 meters. Due to the too - long transmission distance, the voltage loss is too large, resulting in the voltage at the user end being only about 130 - 180V, and even lower, about 120V during peak periods. This has affected the normal electricity use of users. In the power grid system, such users are called "low - voltage users". With the improvement of people's living standards and the popularization of household appliances in rural areas, the power demand has generally been upgraded from the original low - power requirements such as only for lighting and television to diversified high - power electricity demands such as electric cookers, electric farm tools, water heaters, and air conditioners. Therefore, with the rapid economic development, the low - voltage phenomenon has also increased, and the contradiction has become increasingly prominent.

[0003] In summary, due to characteristics such as long transmission distance and dispersed loads, the existing long - distance end lines often face the problem of low voltage. This problem not only affects the normal electricity use of users but also may lead to equipment damage and energy waste. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and system for managing low voltage at the long - distance end of a distribution network, aiming to solve the low - voltage problem existing in the long - distance end lines due to long transmission distance and dispersed loads in traditional technologies.

[0005] In a first aspect, the present invention provides a method for managing low voltage at the long - distance end of a distribution network, which is applied to a photovoltaic - energy - storage - charging - frequency - doubling device. The method includes: Obtain the difference - deficiency power of the line and determine whether the difference - deficiency power is greater than a first preset threshold; If the difference - deficiency power is greater than the first preset threshold, then determine whether the difference - deficiency power is greater than the real - time photovoltaic power; If the difference - deficiency power is less than or equal to the real - time photovoltaic power, then execute a first preset control strategy; If the difference - deficiency power is greater than the real - time photovoltaic power, then determine whether the real - time photovoltaic power is equal to a 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 a third preset threshold; If the battery capacity is greater than the third preset threshold, then execute a second preset control strategy; If the battery capacity is less than or equal to the third preset threshold, then execute a third preset control strategy.

[0006] Further, the step of obtaining the difference - deficiency power of the line includes: Sample each cycle according to a preset sampling rate, and obtain the missing voltage value at the current moment based on the sampling result and the theoretical objective function corresponding to the cycle; Obtain the transient load of the line at the current moment, and calculate the missing power based on the missing voltage value and the transient load.

[0007] Further, after the step of determining whether the photovoltaic real-time power is greater than the second preset threshold if the missing power is greater than the photovoltaic real-time power, the following steps are also included: If the photovoltaic real-time power is not equal to the second preset threshold, execute the fourth preset control strategy.

[0008] Further, after the step of obtaining the missing power of the line and determining whether the missing power is greater than the first preset threshold, the following steps are also included: If the missing power is equal to the first preset threshold, determine whether the photovoltaic real-time power is greater than the third preset threshold; If the photovoltaic real-time power is greater than the third preset threshold, determine whether the photovoltaic real-time power is greater than the battery discharge power; If the photovoltaic real-time power is greater than the battery discharge power, 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, execute the fifth preset control strategy; If the battery capacity is greater than or equal to the fifth preset threshold, execute the sixth preset control strategy.

[0009] Further, after the step of determining whether the photovoltaic real-time power is greater than the battery discharge power, the following steps are also included: If the photovoltaic real-time power is less than the battery discharge power, 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, execute the seventh preset control strategy.

[0010] Further, after the step of determining whether the photovoltaic real-time power is greater than the third preset threshold if the missing power is equal to the first preset threshold, the following steps are also included: If the photovoltaic real-time power is less than or equal to the third preset threshold, 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, execute the eighth preset control strategy.

[0011] Further, the first preset control strategy is: switch to the photovoltaic channel to utilize the photovoltaic energy to achieve waveform superposition, so that ; The second preset control strategy is: switch to the battery channel to make ; The third preset control strategy is: restricting the output power of the battery channel to make , At this time ; The fourth preset control strategy is: switching to the battery and photovoltaic hybrid channel to make ; The fifth preset control strategy is: switching the photovoltaic power to the charging channel and the inverter grid-connection channel respectively to make , ; The sixth preset control strategy is: disconnecting the photovoltaic power from the charging channel, making P bi = 0, and connecting the photovoltaic to the grid-connection channel, making ; The seventh preset control strategy is: switching all the photovoltaic power to the charging channel to make ; The eighth preset control strategy is: connecting the mains power to the charging channel and controlling the charging power so that the voltage of the charging power to the grid incoming line meets: ; Among them, represents the deficit power, represents the compensation power, represents the real-time photovoltaic power, represents the battery charging power, represents the battery discharge power, represents the battery capacity, represents the starting compensation voltage, represents the stopping compensation voltage, represents the user voltage.

[0012] Furthermore, the method further includes: After executing the corresponding control strategy, obtaining the instantaneous voltage value of the next cycle, and calculating a new transient load according to the instantaneous voltage value and the deficit voltage value of the previous cycle; Repeating sampling to obtain the deficit voltage value of the next cycle, and calculating the deficit power of the next cycle according to the deficit voltage value of the next cycle and the new transient load, and performing cyclic monitoring and control on the line according to the deficit power of the next cycle.

[0013] Furthermore, obtaining the deficit power according to the following formula: ; Obtaining the new transient load according to the following formula: ; Among them, represents the instantaneous voltage value, Indicates the difference in voltage value Indicates the instantaneous current value Indicates a new transient load

[0014] In a second aspect, the present invention provides a long-distance end low-voltage governance system for a distribution network, which is applied to a photovoltaic-storage-charging frequency-multiplication device. The system includes: A first difference power detection module, configured to obtain the difference power of a line and determine whether the difference power is greater than a first preset threshold; A second difference power detection module, configured to determine whether the difference power is greater than the real-time photovoltaic power if the difference power is greater than the first preset threshold; A first control module, configured to execute a first preset control strategy if the difference power is less than or equal to the real-time photovoltaic power; A first photovoltaic power detection module, configured to determine whether the real-time photovoltaic power is equal to a second preset threshold if the difference power is greater than the real-time photovoltaic power; A first battery capacity detection module, configured to determine whether the battery capacity is greater than a third preset threshold if the real-time photovoltaic power is equal to the second preset threshold; A second control module, configured to execute a second preset control strategy if the battery capacity is greater than the third preset threshold; A third control module, configured to execute a third preset control strategy if the battery capacity is less than or equal to the third preset threshold.

[0015] In a third aspect, the present invention provides a storage medium that stores one or more programs, and when the program is executed by a processor, the above-mentioned long-distance end low-voltage governance method for a distribution network is implemented.

[0016] In a fourth aspect, the present invention provides an electronic device, which includes a memory and a processor, wherein: The memory is used to store a computer program; The processor is configured to implement the above-mentioned long-distance end low-voltage governance method for a distribution network when executing the computer program stored in the memory.

[0017] Compared with the prior art, the embodiments of the present invention have the following advantages: The present invention obtains the difference power of the line, and dynamically selects corresponding control strategies according to the magnitude of the difference power and parameters such as the real-time photovoltaic power and battery capacity, and fully utilizes the comprehensive advantages of photovoltaic energy and battery energy storage. According to the magnitudes of parameters such as the real-time photovoltaic power and battery capacity, it flexibly switches to the photovoltaic channel, battery channel or hybrid channel for compensation. This method can achieve real-time and precise governance of the low-voltage problem, effectively avoid the problems of slow response speed and limited compensation effect in traditional governance methods, and improve the energy utilization rate at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A flow chart of a method for managing low voltage at the end of a long-distance distribution network proposed in one embodiment of the present invention; Figure 2 A detailed diagram of step S101 proposed in one embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a long-distance terminal low-voltage management system for a distribution network proposed in one embodiment of the present invention.

[0019] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0020] In order to make the purpose, 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0021] like Figure 1 As shown, an embodiment of the present invention provides a method for managing low voltage at the end of a long-distance distribution network, which is applied to a photovoltaic storage and charging stacking device. The method includes steps S01 to S07, wherein: Step S01: obtaining the power difference of the line and determining whether the power difference is greater than a first preset threshold; 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 result and the theoretical target function corresponding to the cycle; The transient load of the line at the current moment is obtained, and the differential power is calculated according to the differential voltage value and the transient load.

[0022] For example, first read the instantaneous current value and instantaneous voltage value of the line at the current moment, calculate the current transient load, perform 128-point voltage segmentation sampling for each cycle at a sampling rate of 6.4K, and compare the sampling results with the theoretical objective function. By calculating the difference of the coaxial time component values, the voltage deficit value of the line at the current time point can be obtained, and then the deficit power can be obtained according to the following formula: .

[0023] Then, taking S as a constant, input the DSP2 objective function to execute the closed-loop gain output PWM modulation waveform, and the modulation period is , , to achieve the deficit power compensation at this point.

[0024] 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; In addition, if the deficit power 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 execute the fifth preset control strategy; If the battery capacity is greater than or equal to the fifth preset threshold, then execute the sixth preset control strategy.

[0025] In addition, 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 execute the seventh preset control strategy.

[0026] Step S03: If the deficit power is less than or equal to the real-time photovoltaic power, then execute the first preset control strategy; Step S04: If the deficit power is greater than the real-time photovoltaic power, then determine whether the real-time photovoltaic power is equal to the second preset threshold; 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; In addition, if the real-time photovoltaic power is not equal to the second preset threshold, then execute the fourth preset control strategy.

[0027] Step S06: If the battery capacity is greater than the third preset threshold, then execute the second preset control strategy; In addition, 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 execute the eighth preset control strategy.

[0028] Step S07: If the battery capacity is less than or equal to the third preset threshold, execute the third preset control strategy.

[0029] Specifically, in some embodiments, the first preset control strategy is: switch to the photovoltaic channel to utilize photovoltaic energy to achieve waveform superposition, so that ; The second preset control strategy is: switch to the battery channel to make ; The third preset control strategy is: limit the output power of the battery channel to make , , at this time ; The fourth preset control strategy is: switch to the battery and photovoltaic hybrid channel to make ; The fifth preset control strategy is: switch the photovoltaic power to the charging channel and the inverter grid-connected channel respectively to make , ; The sixth preset control strategy is: cut off the photovoltaic power from the charging channel to make , and connect the photovoltaic to the grid-connected channel to make ; The seventh preset control strategy is: switch all the photovoltaic power to the charging channel to make ; The eighth preset control strategy is: cut the mains power into the charging channel and control the charging power so that the voltage of the charging power to the grid incoming line meets: ; Among them, represents the deficit power, represents the compensation power, represents the real-time photovoltaic power, represents the battery charging power, represents the battery discharge power, represents the battery capacity, represents the starting compensation voltage, represents the stopping compensation voltage, represents the user voltage.

[0030] Exemplarily, as Figure 2 shown, DSP2 monitors and controls the three sides of photovoltaic, battery, and mains power. The three are connected pairwise and execute the following control logic: 1. When , execute the following control strategy: (1) If , at this time, it indicates that the photovoltaic power generation is sufficient. DSP2 will control the mains power to switch to the photovoltaic channel, and use the photovoltaic energy to achieve waveform superposition, so that the photovoltaic array compensates the power of the mains power. At the same time, the remaining power of the photovoltaic array will be supplied to the battery side, thus making .

[0031] (2) If , and is not zero, at this time, it indicates that it is insufficient to compensate the difference power only by the real-time photovoltaic power. In order to compensate the difference power to the greatest extent, at this time, DSP2 will control the mains power to switch to the battery and photovoltaic hybrid channel, that is, both the battery side and the photovoltaic array will compensate the power of the mains power at the same time, to achieve .

[0032] (3) If , and , at this time, it indicates that the battery capacity is relatively sufficient. DSP2 will control the mains power to switch to the battery channel to compensate the difference power through the battery, thus achieving .

[0033] (4) If , and , at this time, it indicates that there is a low voltage situation in the mains power, and the photovoltaic does not generate electricity at this time, that is, it occurs at night, and at the same time, the charge capacity of the battery itself is insufficient. Based on this, two concepts of starting compensation voltage and stopping compensation voltage are defined. First, DSP2 will limit the output power of the battery channel. At this time , and at the same time make , to achieve .

[0034] Second, when , and , execute the following logic: (5) If , , it indicates that there is no low voltage situation in the mains power at this time, but there is a situation where the charge capacity of the battery side is insufficient. At this time, DSP2 will control all the photovoltaic power of the photovoltaic array to switch to the charging channel, so that the photovoltaic array charges the battery, making .

[0035] (6) , , it indicates that the real-time photovoltaic power is greater than the battery charging power and the charge capacity of the battery is in a relatively sufficient state at this time. At this time, DSP2 will switch the real-time photovoltaic power to the charging channel and the inverter grid-connected channel respectively. That is, on the one hand, the photovoltaic array will charge the battery, and on the other hand, in order to avoid energy waste, the photovoltaic array will compensate the power of the mains power through the inverter grid-connected channel, that is , , but since compensation is not actually required at this time, the grid voltage will float. 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 perform the light rejection operation through PWM chopping.

[0036] (7) , , which indicates that the charge capacity of the battery is full at this time and the photovoltaic array cannot charge it. At this time, DSP2 will cut off the photovoltaic power from the charging channel, that is , and at the same time, the photovoltaic array will be connected to the inverter grid-connected channel to compensate the power of the mains. At this time , similarly, the excess part exceeding the stop compensation voltage will perform chopping light rejection.

[0037] III. When , and , execute the following logic: (8) , which indicates that it is night at this time and the battery may be in a situation of insufficient charge capacity. At this time, DSP2 will control the mains to cut into the charging channel and synchronously control the charging power so that the charging power meets the voltage of the grid incoming line: .

[0038] And monitor the mains incoming line voltage through DSP1 and feedback it to DSP2 to achieve closed-loop dynamic control In addition, in some embodiments, regarding the light rejection operation, it is as follows: DSP1 performs a time integral calculation on the compensation power W to obtain the total watt-hours injected into the grid by the device , and the comprehensive efficiency of discharge and inversion is calculated at 96%; DSP1 performs a time integral calculation on the charging power to obtain the total watt-hours of the charged electricity , and the charging conversion efficiency is calculated at 95%; DSP1 performs a time integral calculation on the self-power consumption of the device to obtain the total watt-hours of self-power consumption ; Therefore, the initial value T0 of the line loss is: ; Then perform an integral calculation on the photovoltaic input power PV in the same time period. When the condition is met, trigger the light rejection operation to achieve the fixed value line loss compensation with the fixed value of this device being zero. For reduced value line loss compensation, it is necessary to meet , and the difference greater than that is the value that needs to be reduced.

[0039] In addition, 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 difference between the instantaneous voltage value and the missing voltage value of the previous cycle; sampling is repeated to obtain the missing voltage value of the next cycle, and the missing power of the next cycle is calculated based on the missing voltage value of the next cycle and the new transient load, and the line is cyclically monitored and controlled based on the missing power of the next cycle. Specifically, the new transient load is obtained according to the following formula: ; wherein, represents the instantaneous voltage value, represents the missing voltage value, represents the instantaneous current value, represents the new transient load; subtracting the missing voltage value of the previous cycle from the instantaneous voltage value is to avoid causing circuit self-excitation.

[0040] Exemplarily, taking the period repeating the above capture, performing cyclic detection and control operation, , and thus completing the compensation for the entire sine wave cycle.

[0041] In summary, according to the above method for governing the low voltage at the long-distance end of the distribution network, by obtaining the missing power of the line, and based on parameters such as the magnitude of the missing power, the real-time photovoltaic power, and the battery capacity, corresponding control strategies are dynamically selected, and the comprehensive advantages of photovoltaic energy and battery energy storage are fully utilized. According to the magnitudes of parameters such as the real-time photovoltaic power and the battery capacity, it is flexibly switched to the photovoltaic channel, the battery channel, or the hybrid channel for compensation. This method can achieve real-time and precise governance of the low voltage problem, effectively avoiding the problems of slow response speed and limited compensation effect in traditional governance methods, and at the same time improving the energy utilization rate.

[0042] As Figure 3 shown, an embodiment of the present invention further provides a system for governing the low voltage at the long-distance end of the distribution network, which is applied to a photovoltaic-storage-charging frequency-doubling device. The system includes: The first missing power detection module 10 is used to obtain the missing power of the line and determine whether the missing power is greater than a first preset threshold; The second missing power detection module 20 is used to, if the missing power is greater than the first preset threshold, determine whether the missing power is greater than the real-time photovoltaic power; The first control module 30 is used to, if the missing power is less than or equal to the real-time photovoltaic power, execute a first preset control strategy; The first photovoltaic power detection module 40 is used to, if the missing power is greater than the real-time photovoltaic power, determine whether the real-time photovoltaic power is equal to a second preset threshold; The first battery capacity detection module 50 is used to determine whether the battery capacity is greater than a third preset threshold if the real-time photovoltaic power is equal to a second preset threshold; The second control module 60 is used to execute a second preset control strategy if the battery capacity is greater than the third preset threshold; The third control module 70 is used to execute a third preset control strategy if the battery capacity is less than or equal to the third preset threshold.

[0043] In addition, in some embodiments, the system further includes: 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.

[0044] In addition, in some embodiments, the system further includes: The third power deficit detection module is used to determine whether the real-time photovoltaic power is greater than a third preset threshold if the power deficit is equal to a first preset threshold; 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; The second battery capacity detection module is used to determine whether the battery capacity is greater than a fourth preset threshold and less than a fifth preset threshold if the real-time photovoltaic power is greater than the battery discharge power; The fifth control module is used to execute a fifth preset control strategy if the battery capacity is greater than the fourth preset threshold and less than the fifth preset threshold; The sixth control module is used to execute a sixth preset control strategy if the battery capacity is greater than or equal to the fifth preset threshold.

[0045] In addition, in some embodiments, the system further includes: 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; The seventh control module is used to execute a seventh preset control strategy if the battery capacity is less than or equal to the fourth preset threshold.

[0046] In addition, in some embodiments, the system further includes: 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; The eighth control module is used to execute an eighth preset control strategy if the battery capacity is less than or equal to the fourth preset threshold.

[0047] In addition, in some embodiments, the system further includes: A transient load calculation module, configured to obtain an instantaneous voltage value of the next cycle after executing the corresponding control strategy, and calculate a new transient load according to the difference between the instantaneous voltage value and the voltage deficiency value of the previous cycle; A repeated sampling module, configured to perform repeated sampling to obtain the voltage deficiency value of the next cycle, calculate the power deficiency of the next cycle according to the voltage deficiency value of the next cycle and the new transient load, and perform cyclic monitoring and control on the line according to the power deficiency of the next cycle.

[0048] On the other hand, the present invention also provides a storage medium, on which one or more programs are stored, and when the program is executed by a processor, the above-mentioned method for governing low voltage at the long-distance end of a distribution network is implemented.

[0049] On the other hand, the present invention also provides 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 on the memory to implement the above-mentioned method for governing low voltage at the long-distance end of a distribution network.

[0050] Those skilled in the art can 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 specifically implemented in any computer-readable medium for use by an instruction execution system, apparatus, or device (such as a computer-based system, a system including a processor, or other systems that can fetch and execute instructions from the instruction execution system, apparatus, or device), or used in combination with these instruction execution systems, apparatus, or devices. For the purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

[0051] More specific examples (non-exhaustive list) of computer-readable media include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer diskette (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). Additionally, the computer-readable medium 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 media, followed by editing, interpretation, or other appropriate processing as necessary, and then stored in a computer memory.

[0052] It should be understood that various parts of the present invention can be implemented by hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0053] Although the embodiments of the present invention have been described in detail above, it is obvious to those skilled in the art that various modifications and changes can be made to these embodiments. However, it should be understood that such modifications and changes are all within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein can have other embodiments and can be implemented or realized in various ways.

Claims

1. A method for managing low voltage at the long-distance end of a distribution network, which is applied to a photovoltaic-storage-charging superposition frequency device, is characterized in that The method includes: Obtaining the deficit power of the line and determining whether the deficit power is greater than a first preset threshold; If the deficit power is greater than the first preset threshold, determining whether the deficit power is greater than the real-time photovoltaic power; If the deficit power is less than or equal to the real-time photovoltaic power, implementing a first preset control strategy; If the deficit power is greater than the real-time photovoltaic power, determining whether the real-time photovoltaic power is equal to a second preset threshold; If the real-time photovoltaic power is equal to the second preset threshold, determining whether the battery capacity is greater than a third preset threshold; If the battery capacity is greater than the third preset threshold, implementing a second preset control strategy; If the battery capacity is less than or equal to the third preset threshold, implementing a third preset control strategy.

2. The method for governing low voltage at the long-distance end of a distribution network according to claim 1, wherein The step of obtaining the deficit power of the line includes: Sampling each cycle according to a preset sampling rate, and obtaining the deficit voltage value at the current moment according to the sampling result and the theoretical objective function corresponding to the cycle; Obtaining the transient load of the line at the current moment, and calculating the deficit power according to the deficit voltage value and the transient load.

3. The low-voltage governance method for the long-distance end of the distribution network according to claim 1, characterized in that After the step of if the deficit power is greater than the real-time photovoltaic power, determining whether the real-time photovoltaic power is equal to the second preset threshold, it further includes: If the real-time photovoltaic power is not equal to the second preset threshold, implementing a fourth preset control strategy.

4. The low-voltage governance method for the long-distance end of the distribution network according to claim 3, characterized in that After the step of obtaining the deficit power of the line and determining whether the deficit power is greater than the first preset threshold, it further includes: If the deficit power is equal to the first preset threshold, determining whether the real-time photovoltaic power is greater than a third preset threshold; If the real-time photovoltaic power is greater than the third preset threshold, determining 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, determining whether the battery capacity is greater than a fourth preset threshold and less than a fifth preset threshold; If the battery capacity is greater than the fourth preset threshold and less than the fifth preset threshold, implementing a fifth preset control strategy; If the battery capacity is greater than or equal to the fifth preset threshold, implementing a sixth preset control strategy.

5. The method for low voltage management at the long-distance end of a distribution network according to claim 4, characterized in that, After the step of determining whether the real-time photovoltaic power is greater than the battery discharge power, it further includes: If the real-time photovoltaic power is less than the battery discharge power, determining 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, implementing a seventh preset control strategy.

6. The method for low voltage management at the long-distance end of a distribution network according to claim 5, characterized in that After the step of if the deficit power is equal to the first preset threshold, determining whether the real-time photovoltaic power is greater than the third preset threshold, it further includes: If the real-time photovoltaic power is less than or equal to the third preset threshold, determining 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, implementing an eighth preset control strategy.

7. The low-voltage governance method for the long-distance end of the distribution network according to any one of claims 1-6, characterized in that, The first preset control strategy is: switch to the photovoltaic channel to utilize photovoltaic energy to achieve waveform superposition, so that ; The second preset control strategy is: switch to the battery channel so that ; The third preset control strategy is: restricting the output power of the battery channel so that , , at this time ; The fourth preset control strategy is: switch to the battery and photovoltaic hybrid channel so that ; The fifth preset control strategy is: switch the photovoltaic power to the charging channel and the inverter grid-connected channel respectively, so that , ; The sixth preset control strategy is: disconnect the photovoltaic power from the charging channel, so that , and connect the photovoltaic to the grid-connected channel, so that ; The seventh preset control strategy is: fully switch the photovoltaic power to the charging channel so that ; The eighth preset control strategy is: switch the mains power supply to the charging channel and control the charging power so that the voltage of the charging power to the grid incoming line meets: ; Among them, represents the difference power shortage, represents the compensation power, represents the real-time photovoltaic power, represents the battery charging power, represents the battery discharging power, represents the battery capacity, represents the starting compensation voltage, represents the stopping compensation voltage, represents the user voltage.

8. The low-voltage governance method for the long-distance end of the distribution network according to any one of claims 1-6, characterized in that, The method further includes: After implementing the corresponding control strategy, obtaining the instantaneous voltage value of the next cycle, and calculating a new transient load according to the instantaneous voltage value and the deficit voltage value of the previous cycle; Repeating the sampling to obtain the deficit voltage value of the next cycle, calculating the deficit power of the next cycle according to the deficit voltage value of the next cycle and the new transient load, and performing cyclic monitoring and control on the line according to the deficit power of the next cycle.

9. The method for low voltage governance at the long-distance end of a distribution network according to claim 8, characterized in that, Obtain the deficit power according to the following formula: ； Obtain the new transient load according to the following formula: ； Among them, represents the instantaneous voltage value, represents the differential voltage value, represents the instantaneous current value, represents the new transient load.

10. A long-distance low-voltage governance system for the end of a distribution network, which is applied to a photovoltaic-storage-charging frequency-doubling device, is characterized in that The system includes: A first deficit power detection module, configured to obtain the deficit power of the line and determine whether the deficit power is greater than a first preset threshold; A second deficit power detection module, configured to determine whether the deficit power is greater than the photovoltaic real-time power if the deficit power is greater than the first preset threshold; A first control module, configured to execute a first preset control strategy if the deficit power is less than or equal to the photovoltaic real-time power; A first photovoltaic power detection module, configured to determine whether the photovoltaic real-time power is equal to a second preset threshold if the deficit power is greater than the photovoltaic real-time power; A first battery capacity detection module, configured to determine whether the battery capacity is greater than a third preset threshold if the photovoltaic real-time power is equal to the second preset threshold; A second control module, configured to execute a second preset control strategy if the battery capacity is greater than the third preset threshold; A third control module, configured to execute a third preset control strategy if the battery capacity is less than or equal to the third preset threshold.

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