Method and device for regulating terminal grid voltage based on user-side energy storage inverter

Abstract

This invention discloses a method and apparatus for regulating the voltage of the end-user grid based on a user-side energy storage inverter. The method includes the following steps: S1, a start-up judgment step; S2, a voltage regulation step, in which the line impedance at the grid connection point of the energy storage inverter is calculated, and when the calculated line impedance is greater than a preset impedance threshold, a voltage regulation mode is initiated; wherein, the first voltage threshold is lower than the grid rated voltage Vn, and the second voltage threshold is higher than the grid rated voltage Vn. This invention directly compensates for the voltage deviation at the end caused by line impedance by actively injecting or absorbing active power, which can not only ensure the stability of the electricity voltage at the end-user side, but also reduce transmission line losses, supplement power during peak electricity consumption, reduce the burden on the grid, and improve power quality.

Description

Technical Field

[0001] This invention relates to the field of power system control technology, and in particular to a method and apparatus for regulating the voltage of the end grid based on a user-side energy storage inverter. Background Technology

[0002] Existing energy storage inverters typically have the following functions: storing excess electricity during the day for nighttime use, reducing reliance on the power grid; serving as an emergency backup power source, providing continuous power when the power grid fails, ensuring power supply for critical equipment; and peak-valley arbitrage, charging the battery during off-peak hours when electricity prices are low, and using the battery to power the battery during peak hours when electricity prices are high, reducing electricity costs.

[0003] On the other hand, in a power system, electrical energy travels from power plants through high-voltage transmission and medium-voltage distribution, finally being reduced to the voltage used by users (e.g., 220V / 380V) via distribution transformers. Due to the impedance R of transmission lines, a voltage drop occurs when current flows through them, causing the voltage at the end of the line to be lower than at the beginning. Especially in areas with long lines and heavy loads, the voltage at the end of the transmission line may be lower than the allowable range of national standards, affecting users' normal electricity consumption. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a method and apparatus for regulating the voltage of the end grid based on the user-side energy storage inverter, so as to ensure the stability of the power supply voltage on the user side of the end grid by charging or discharging the end grid through the energy storage inverter.

[0005] This invention is achieved using the following technical solution:

[0006] On the one hand, the method for regulating the terminal grid voltage based on the user-side energy storage inverter includes the following steps: S1, start-up judgment step: calculate the line impedance of the grid connection point where the energy storage inverter is located, and start the voltage regulation mode when the calculated line impedance is greater than a preset impedance threshold; S2, voltage regulation step: in the voltage regulation mode, monitor the grid voltage at the grid connection point in real time; when the grid voltage is lower than a first voltage threshold, control the energy storage inverter to perform a discharge operation, and generate a positive voltage drop that raises the voltage on the line impedance by injecting active current into the grid, so as to increase the voltage at the grid connection point; when the grid voltage is higher than a second voltage threshold, control the energy storage inverter to perform a charging operation, and generate a reverse voltage drop that lowers the voltage on the line impedance by absorbing active current from the grid, so as to reduce the voltage at the grid connection point; wherein, the first voltage threshold is lower than the grid rated voltage Vn, and the second voltage threshold is higher than the grid rated voltage Vn.

[0007] Preferably, the step of calculating the line impedance in the start-up judgment step S1 includes: recording the current initial value V of the grid voltage; controlling the energy storage inverter to increase the charging power at a preset first power change rate, and recording the first voltage when the first stop condition is reached. and first power The energy storage inverter is controlled to increase the discharge power at a preset second power change rate, and the second voltage is recorded when the second stop condition is reached. Second power Calculate the line impedance Z based on the recorded data; The impedance calculation formula is as follows: .

[0008] Preferably, the first stopping condition is: the grid voltage drops to the first voltage threshold, or the charging power reaches the maximum allowable charging power of the energy storage inverter; the second stopping condition is: the grid voltage rises to the second voltage threshold, or the discharging power reaches the maximum allowable discharging power of the energy storage inverter.

[0009] Preferably, before the start-up determination step, the method further includes: accepting user instructions.

[0010] Preferably, in voltage regulation step S2, the specific steps for generating the target current command based on the comparison result between the grid voltage and the threshold include: calculating a first difference between the first voltage threshold and the real-time grid voltage Vg, and performing a first PI regulation on the first difference; performing a first limiting process on the output of the first PI regulation: the output is 0 when the first difference is less than 0, and a positive value when the first difference is greater than 0; calculating a second difference between the real-time grid voltage Vg and the second voltage threshold, and performing a second PI regulation on the second difference; performing a second limiting process on the output of the second PI regulation: the output is 0 when the second difference is less than 0, and a negative value when the second difference is greater than 0; adding the output after the first limiting process and the output after the second limiting process to obtain the target current command; a positive total current command corresponds to a discharge operation, a negative total current command corresponds to a charging operation, and no operation is performed when the total current command is zero.

[0011] Preferably, the method further includes controlling the switching devices of the energy storage inverter according to the target current command: calculating the error between the actual sampled current and the target current; and performing current loop PI regulation on the error to generate a PWM control signal to drive the switching devices.

[0012] Preferably, performing current loop PI regulation on the error to generate a PWM control signal to drive the switching device specifically includes: adjusting the current cycle error... The error of P compared to the previous N periods The sum of P and I yields the error adjustment value, where P is the proportional coefficient, I is the integral coefficient, and N is a preset value. A positive error adjustment value generates a high level, and a negative error adjustment value generates a low level. This generates a PWM control signal, which controls the charging and discharging power by controlling the duty cycle of the switching devices, thereby achieving precise control of the charging and discharging current.

[0013] Preferably, before calculating the error, the method further includes: limiting the maximum charging current and maximum discharging current of the target current command; to obtain the target current.

[0014] Preferably, the first voltage threshold is 0.9 times the grid rated voltage Vn, and the second voltage threshold is 1.1 times the grid rated voltage Vn.

[0015] On the other hand, the present invention also provides an apparatus for regulating the end grid voltage based on a user-side energy storage inverter, comprising: a voltage sensor for real-time monitoring of the grid voltage at the grid connection point; an energy storage device including a battery pack and an energy storage inverter connected between the battery pack and the grid; and a controller communicatively connected to the voltage sensor and the energy storage device, configured to perform the method as described in any of the preceding claims.

[0016] Compared to existing technologies, the advantages of this invention are as follows: This invention innovatively utilizes a user-side energy storage inverter to directly compensate for voltage deviations at the end of the grid caused by line impedance through active power injection or absorption. This maintains stable voltage at the user side, reduces transmission line losses, and supplements power during peak demand periods, alleviating grid burden and improving power quality. The invention also features a unique start-up control logic based on end-grid line impedance identification. Voltage regulation is automatically activated only when line impedance is high and voltage fluctuations are severe; when line impedance is low and voltage quality is good, the system maintains its normal operating mode. This design avoids unnecessary frequent charging and discharging of the energy storage system, saving battery cycle life, reducing unnecessary system losses, and improving overall energy efficiency and economy. Furthermore, the voltage and current PI control logic nested within the power control loop of the energy storage inverter enables millisecond-level rapid detection and power response to grid voltage fluctuations, resulting in fast dynamic response and high adjustment accuracy. The adjustment process is smooth and without steady-state error, providing a user experience that is "almost imperceptible," far faster than traditional methods such as mechanical voltage regulators or transformer tap adjustments. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a voltage regulation application scenario of this application; Figure 2 This is a flowchart of a line impedance calculation method according to an embodiment of this application; Figure 3This is a block diagram of voltage regulation control logic according to an embodiment of this application; Figure 4 This is a block diagram of an embodiment of the present application. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0020] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0021] Example 1: refer to Figure 1 This is a typical application scenario provided in this embodiment. The energy storage inverter 1 is connected in parallel with the user-end load 2 in the terminal power grid 3, and the battery 4 is electrically connected to the energy storage inverter 1 through a wire. It should be noted that there is a line impedance Z in the terminal power grid 3, which is different from the impedance R of the transmission line.

[0022] refer to Figures 1-4 The method for regulating the terminal grid voltage based on user-side energy storage inverters includes the following steps: S1. Receive user instructions and start the judgment process: calculate the line impedance of the grid connection point of the energy storage inverter. When the calculated line impedance exceeds the preset impedance threshold, start the voltage regulation mode. Among them, reference Figure 2 Step S1 specifically includes: S11. Receive user instruction and start impedance judgment process; Users can send a start command by pressing a button. After receiving the user's command, the controller will start the impedance judgment process.

[0023] S12. Record the current initial value of the mains voltage. ; S13. Control the energy storage inverter to charge in order to reduce the grid voltage; The energy storage inverter is controlled to increase the charging power at a preset first power change rate to absorb active current from the end grid. The purpose is to actively cause the grid voltage to decrease. In this embodiment, the preset first power change rate is 100W.

[0024] S14. Determine whether the current grid voltage Vg has dropped to the first voltage threshold. If yes, proceed to step S15; otherwise, proceed to step S16. The first voltage threshold is set to 0.9Vn, where Vn is the rated voltage (e.g., 220V or 380V).

[0025] S15, record the current first power P1 and the current first voltage V1 of the energy storage inverter, then proceed to step S17; first power The current charging power of the energy storage inverter; the first voltage V1 is the current grid voltage; S16, determine whether the current charging power has reached the maximum allowable charging power of the energy storage inverter. If yes, proceed to step S13; otherwise, proceed to step S15. S17, control the energy storage inverter to discharge in order to raise the grid voltage; The energy storage inverter is controlled to increase the discharge power at a preset second power change rate to inject active current into the end grid. The purpose is to actively cause the grid voltage to rise and change so as to facilitate impedance calculation. In this embodiment, the preset second power change rate is 100W.

[0026] S18, determine whether the current grid voltage Vg has risen to the second voltage threshold. If yes, proceed to step S19; otherwise, proceed to step S20. The second voltage threshold is set to 1.1Vn, where Vn is the rated voltage (e.g., 220V or 380V).

[0027] S19, records the second power of the current energy storage inverter. And the current second voltage Then proceed to step S21; second power The current discharge power of the energy storage inverter; the second voltage V2 is the current grid voltage; S110, determine whether the current discharge power has reached the maximum allowable discharge power of the energy storage inverter. If yes, proceed to step S19; otherwise, proceed to step S17. S111, calculate the line impedance Z based on the recorded data, and then proceed to step S22; The impedance calculation formula is as follows: .

[0028] As can be seen from this, controlling the energy storage inverter to discharge to raise the grid voltage and controlling the energy storage inverter to charge to lower the grid voltage can respectively calculate a line impedance Z. The purpose is to confirm the calculated results to avoid abnormal data collection and incorrect start-up judgment. If the calculated results of the charging and discharging actions are the same, the resistance value of the line impedance Z is confirmed, and the process proceeds to step S112. If the results are different, it indicates that the collected data is abnormal. In other embodiments, the process can re-enter step S13, repeat the charging and discharging actions, and re-collect data. As can be seen from the above description, the charging and discharging actions are both for obtaining a set of values. That is to say, the order of the charging and discharging actions is not limited to the current embodiment. The order of steps S17-S20 and steps S13-S16 can also be interchanged without affecting data collection.

[0029] S112. Determine whether the line impedance Z has reached the preset impedance threshold Zn. If yes, proceed to step S23; otherwise, proceed to step S24. S113. If the line impedance Z is too high, activate the voltage regulation mode. S114. If the line impedance Z is determined to be small, the voltage regulation mode is turned off.

[0030] S2. Voltage regulation step: In the voltage regulation mode, the grid voltage Vg at the grid connection point is monitored in real time and the grid voltage is regulated; the energy storage inverter executes the voltage regulation logic nested in the inverter power control loop.

[0031] Among them, reference Figure 3 Step S2 specifically includes: S21. Construct an error loop between the first voltage threshold (0.9Vn) and the current real-time grid voltage Vg, and calculate the first difference between the first voltage threshold and the real-time grid voltage Vg.

[0032] S22. Perform a first PI adjustment on the first difference; wherein, PI adjustment (proportional-integral adjustment) is a feedback controller that regulates the system through proportional (P) and integral (I) control actions. The proportional action quickly adjusts the output according to the deviation, but has a steady-state error; the integral action eliminates the steady-state error by accumulating the deviation. The PI controller combines the advantages of both to achieve fast response and error-free control. The core objective of the PI adjustment error loop is to dynamically minimize the error between the system output and the setpoint through proportional (P) and integral (I) actions, where the proportional term responds quickly based on the current deviation, and the integral term eliminates the steady-state error by accumulating historical errors.

[0033] S23. Perform a first limiting process on the output of the first PI regulation. When the first difference is less than 0, the output is 0, and when the first difference is greater than 0, the output is positive.

[0034] S24. Construct an error loop between the current real-time grid voltage Vg and the second voltage threshold (1.1Vn), and calculate the second difference between the real-time grid voltage Vg and the second voltage threshold.

[0035] S25. Perform a second PI adjustment on the second difference.

[0036] S26. Perform a second limiting process on the output of the second PI regulation. When the second difference is less than 0, the output is 0. When the second difference is greater than 0, the output is negative.

[0037] S27. Add the output after the first limiting process to the output after the second limiting process to obtain the target current command.

[0038] Calculations show that when Vg < 0.9Vn, the output current command is positive, corresponding to the energy storage inverter injecting active current into the grid, generating a positive voltage drop across the line impedance to raise the voltage at the grid connection point. When 0.9Vn < Vg < 1.1Vn, the output current command is zero, and no voltage regulation is performed. When Vg > 1.1Vn, the output current command is negative, corresponding to the energy storage inverter absorbing active current from the grid.

[0039] In the specific control process, when the voltage regulation mode is activated, the energy storage inverter first monitors the actual grid voltage Vg in real time. This real-time voltage Vg is compared with the set first voltage threshold of 0.9Vn and the second voltage threshold of 1.1Vn. For low voltage conditions, an error loop is constructed. When the actual voltage Vg is below 0.9Vn, the error loop output is positive; conversely, when Vg is above 0.9Vn, the error loop output is negative. This error signal then enters the PI regulation module, which quickly responds to the current voltage deviation through the proportional (P) stage and gradually eliminates the static error through the integral (I) stage, ensuring the accuracy and stability of the regulation. The PI-regulated signal then undergoes amplitude limiting processing. When the input signal is negative, the output is set to 0, meaning that within the normal range where Vg is above 0.9Vn, the low-voltage regulation loop does not function and does not interfere with grid discharge. When the input signal is positive, the output is positive, triggering the discharge regulation mechanism.

[0040] Meanwhile, for high-voltage conditions, an additional error loop is set up to compare the actual voltage Vg with a second voltage threshold of 1.1Vn. When Vg is higher than 1.1Vn, the error loop output is negative, initiating charging regulation; when Vg is lower than 1.1Vn, the error loop output is positive. Similarly, this error signal is also PI-regulated to achieve a fast and steady-state error-free response to overvoltage conditions. Subsequent limiting is set so that the output is 0 when the input signal is positive, ensuring that within the normal range where Vg is lower than 1.1Vn, the high-voltage regulation loop does not initiate charging operation.

[0041] The outputs of the low-voltage regulation loop and the high-voltage regulation loop are superimposed. Thus, when the actual voltage Vg is below 0.9Vn, the low-voltage loop output is positive, the high-voltage loop output is 0, and the superimposed result is positive. The energy storage inverter performs a discharge operation, injecting energy into the grid to boost the terminal voltage. When Vg is above 1.1Vn, the high-voltage loop output is negative, the low-voltage loop output is 0, and the superimposed result is negative. The energy storage inverter performs a charging operation, absorbing energy from the grid to lower the terminal voltage. When Vg is within the normal voltage range of 0.9Vn to 1.1Vn, the outputs of both loops are 0, the superimposed result is 0, and the energy storage inverter does not perform any additional voltage regulation operation.

[0042] S28. Limit the maximum charging current and maximum discharging current of the target current command to obtain the target current icref, so as to ensure that the total current command does not exceed the safe operating range of the energy storage inverter and the battery.

[0043] S29, construct the error loop between the actual sampled current ic and the target current icref, and calculate the error between the actual sampled current and the target current.

[0044] S210, the error is adjusted by current loop PI regulation; Current cycle error The error of P compared to the previous N periods The sum of P and I yields the error adjustment value, where P is the proportional coefficient, I is the integral coefficient, and N is a preset value. A high level is generated when the error adjustment value is positive, and a low level is generated when the error adjustment value is negative, thus generating a PWM control signal.

[0045] S211. The power of charging and discharging is controlled by controlling the duty cycle of the switching device through the PWM control signal, thereby achieving precise control of the charging and discharging current.

[0046] The voltage and current loops described above are regulated by a PI controller. The proportional term (P) responds quickly to the current error, while the integral term (I) eliminates steady-state deviation. The output of the current loop PI controller generates a PWM control signal to drive the inverter's switching devices, thereby changing the output current and achieving millisecond-level regulation of the grid voltage (response time <100ms), thus achieving rapid stabilization of the terminal voltage. Through the above embodiments, this invention can effectively solve the problem of unstable voltage at the grid terminal and has the advantages of sensorless regulation and fast response. In addition, since the terminal grid is usually in a state below the rated voltage, after the voltage of the terminal grid is increased by the energy storage inverter, the voltage across the impedance R of the transmission line decreases, thereby reducing the power loss of the transmission line.

[0047] Example 2: refer to Figure 1 and Figure 4Based on the same inventive concept as Embodiment 1, this embodiment provides a device for regulating the end-grid voltage based on a user-side energy storage inverter. The device includes an energy storage device, a voltage sampling module, a current sampling module, a control module, and a human-machine interface module. The energy storage device includes a battery pack and an energy storage inverter connected between the battery pack and the grid. The energy storage inverter is connected in parallel to the end-grid with the user-side load. The voltage sampling module is used to collect the grid voltage Vg at the grid connection point of the energy storage inverter in real time and transmit the collected voltage signal to the control module. The current sampling module is used to collect the charging and discharging current ic of the energy storage inverter and also feeds the current signal back to the control module. The control module, as the core of the device, has a built-in processor and memory. The memory stores executable program code. When the processor executes the program code, it implements the method for regulating the end-grid voltage based on a user-side energy storage inverter as described in Embodiment 1. Specifically, the control module receives user commands from the human-machine interface module to initiate a judgment process, calculates the line impedance Z based on the data fed back by the voltage sampling module and the current sampling module, and initiates a voltage regulation mode when Z exceeds a preset threshold. In voltage regulation mode, the control module generates a target current command (icref) based on the real-time monitored grid voltage (Vg) using an internally preset algorithm (including error loop construction, PI regulation, and amplitude limiting). This is further processed by the current loop PI regulation to generate a PWM control signal, which controls the switching devices in the energy storage inverter to turn on and off. This achieves precise control of charging and discharging power and current, thus regulating the grid voltage at the end of the power grid. The human-machine interface module includes buttons, indicator lights, and a display screen to receive user-input start commands, display the device's operating status (such as whether it is in voltage regulation mode, the current grid voltage value, and line impedance value), and potential fault information, allowing users to intuitively understand the device's operation and perform necessary operations. Through the organic combination of hardware and software, this device can stably and quickly respond to fluctuations in the grid voltage at the end of the power grid, achieving seamless regulation, effectively improving the voltage quality of the grid at the end of the power grid, and reducing line losses.

[0048] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for regulating the voltage of the end-grid based on a user-side energy storage inverter, characterized in that, include: S1. Start-up judgment: Calculate the line impedance at the grid connection point where the energy storage inverter is located, and start the voltage regulation mode when the calculated line impedance is greater than the preset impedance threshold. S2. Voltage Regulation: In the voltage regulation mode, the grid voltage at the grid connection point is monitored in real time; When the grid voltage is lower than the first voltage threshold, the energy storage inverter is controlled to perform a discharge operation. By injecting active current into the grid, a positive voltage drop that raises the voltage is generated across the line impedance, thereby increasing the voltage at the grid connection point. When the grid voltage is higher than the second voltage threshold, the energy storage inverter is controlled to perform a charging operation. By absorbing active current from the grid, a reverse voltage drop is generated on the line impedance to reduce the voltage at the grid connection point. Wherein, the first voltage threshold is lower than the grid rated voltage Vn, and the second voltage threshold is higher than the grid rated voltage Vn.

2. The method for regulating the terminal grid voltage based on a user-side energy storage inverter according to claim 1, characterized in that, In step S1, the calculation of the line impedance includes: Record the initial value V of the current grid voltage; The energy storage inverter is controlled to increase the charging power at a preset first power change rate, and a first voltage is recorded when a first stopping condition is reached. and first power The energy storage inverter is controlled to increase the discharge power at a preset second power change rate, and the second voltage is recorded when the second stop condition is reached. Second power ; Calculate the line impedance Z based on the recorded data; The impedance calculation formula is as follows: .

3. The method for regulating the terminal grid voltage based on a user-side energy storage inverter according to claim 2, characterized in that: The first stopping condition is: the grid voltage drops to the first voltage threshold, or the charging power reaches the maximum allowable charging power of the energy storage inverter; The second stopping condition is: the grid voltage rises to the second voltage threshold, or the discharge power reaches the maximum allowable discharge power of the energy storage inverter.

4. The method for regulating the terminal grid voltage based on a user-side energy storage inverter according to any one of claims 1-3, characterized in that, Before the control activation decision, it also includes: Accept user instructions.

5. The method for regulating the terminal grid voltage based on a user-side energy storage inverter according to claim 1, characterized in that, In step S2, generating the target current command based on the comparison result between the grid voltage and the threshold includes: Calculate the first difference between the first voltage threshold and the real-time grid voltage Vg, and apply a first PI adjustment to the first difference; The output of the first PI regulator is subjected to a first limiting process: when the first difference is less than 0, the output is 0; when the first difference is greater than 0, the output is positive. Calculate the second difference between the real-time grid voltage Vg and the second voltage threshold, and apply a second PI adjustment to the second difference; The output of the second PI regulation is subjected to a second limiting process: when the second difference is less than 0, the output is 0; when the second difference is greater than 0, the output is negative. The output after the first limiting process is added to the output after the second limiting process to obtain the target current command; when the total current command is positive, it corresponds to a discharge operation; when it is negative, it corresponds to a charging operation; and when it is zero, no operation is performed.

6. The power grid terminal voltage regulation method according to claim 5, characterized in that, It also includes switching devices that control the energy storage inverter according to the target current command: Calculate the error between the actual sampled current and the target current; The error is PI-regulated using a current loop to generate a PWM control signal to drive the switching device.

7. The method for regulating the terminal grid voltage based on a user-side energy storage inverter according to claim 6, characterized in that, The process of applying a current loop PI control to the error to generate a PWM control signal to drive the switching device specifically includes: Current cycle error The error of P compared to the previous N periods The sum of I and P yields the error adjustment value, where P is the proportional coefficient, I is the integral coefficient, and N is the preset value. A high level is generated when the error adjustment value is positive, and a low level is generated when the error adjustment value is negative. This generates a PWM control signal, which controls the charging and discharging power by controlling the duty cycle of the switching device, thereby achieving precise control of the charging and discharging current.

8. The method for regulating the terminal grid voltage based on a user-side energy storage inverter according to any one of claims 6 or 7, characterized in that, Before calculating the error, the following is also included: The target current command is subjected to maximum charging current and maximum discharging current limiting processing to obtain the target current.

9. The method for regulating the terminal grid voltage based on a user-side energy storage inverter according to claim 1, characterized in that, The first voltage threshold is 0.9 times the grid rated voltage Vn, and the second voltage threshold is 1.1 times the grid rated voltage Vn.

10. A device for regulating the voltage of the terminal grid based on a user-side energy storage inverter, characterized in that, include: The energy storage device includes a battery pack and an energy storage inverter connected between the battery pack and the power grid, wherein the energy storage inverter is connected in parallel with the user-end load to the end power grid; The voltage sampling module is used to collect the grid voltage at the grid connection point of the energy storage inverter in real time and transmit the collected voltage signal to the control module. The current sampling module is used to collect the charging and discharging current of the energy storage inverter and feed the current signal back to the control module; The human-computer interaction module, which communicates with the control module, includes buttons and a display screen, and is used to receive user input start commands and display the working status of the device; The control module has a built-in processor and a memory. The memory stores executable program code. When the processor executes the program code, it implements the method as described in any one of claims 1 to 9.

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