Electric energy quality adjusting method and system of optical storage coupling inverter

Abstract

The invention provides an electric energy quality adjusting method and system for a light storage coupling inverter, and the method comprises the steps: collecting the electrical parameters of a grid-connected point in real time, calculating the electric energy quality parameters, judging whether the parameters exceed the standard or not, generating a cooperative control strategy through integrating the photovoltaic real-time output, the energy storage charge state and the problem type, and finally controlling the inverter to execute compensation operation. The electric energy quality adjusting system comprises a monitoring module, a calculation and analysis module, a cooperative control decision module and an inverter control module, relates to the technical field of new energy power generation, can realize comprehensive treatment of various electric energy quality problems without additional special equipment and reuse of existing hardware resources, improves system economy and power grid friendliness, and is suitable for large-scale popularization and application. The method is suitable for a distributed optical storage grid-connected system.

Description

Technical Field

[0001] This invention relates to the field of new energy power generation technology, and in particular to a power quality regulation method and system for a photovoltaic-storage coupled inverter. Background Technology

[0002] With the large-scale integration of distributed generation systems such as photovoltaics into the power grid, their randomness and intermittency have brought numerous challenges to the power quality of the grid, such as voltage fluctuations and sags, harmonic pollution, reduced power factor, and frequency deviations. At the same time, industrial production and residential life are constantly increasing their requirements for the stability and reliability of power supply, making power quality a key factor affecting the safe and efficient operation of the power grid.

[0003] Currently, traditional solutions for improving power quality mainly rely on installing dedicated compensation devices, such as active power filters (APFs) to suppress harmonics and static var compensators (SVGs) to regulate reactive power and voltage. However, such devices require additional hardware costs, which not only increases system complexity and floor space but also raises the overall expenses for equipment procurement, installation, and operation and maintenance, hindering the low-cost promotion of distributed photovoltaic systems.

[0004] Photovoltaic-storage (PV-SES) coupled systems combine photovoltaic (PV) power generation units with energy storage units, using bidirectional inverters to switch between grid-connected and off-grid operation, effectively improving energy utilization efficiency and power supply reliability. However, existing control strategies for PV-SES inverters primarily focus on core energy conversion functions, such as maximum power point tracking (MPPT) for PV power generation, charge and discharge management of energy storage units, and smooth switching between grid-connected and off-grid modes. They lack proactive and coordinated adjustment capabilities for power quality issues arising from the grid itself or introduced by PV grid connection. Even if some inverters possess basic reactive power regulation functions, they fail to fully exploit the synergistic potential of remaining PV capacity and flexible charge and discharge of energy storage, thus failing to comprehensively address various power quality issues and resulting in the underutilization of the added value of PV-SES systems.

[0005] Therefore, how to tap the control and capacity potential of photovoltaic-storage coupling systems without significantly increasing hardware costs, so that they can perform the core function of energy conversion while possessing proactive and intelligent power quality regulation capabilities, has become an urgent technical problem to be solved in the field of new energy power generation. Summary of the Invention

[0006] To overcome existing problems, this application provides a power quality regulation method and system for a photovoltaic-storage coupled inverter. The aim is to overcome the shortcomings of the prior art, such as high cost due to reliance on dedicated compensation devices, insufficient power quality regulation capability of photovoltaic-storage systems, and inability to comprehensively manage multiple problems. The application provides a power quality regulation method and system for a photovoltaic-storage coupled inverter to achieve collaborative management of multiple power quality problems without additional hardware, at low cost and with high efficiency.

[0007] The technical solution adopted by the embodiments of this application to solve its technical problem is:

[0008] A power quality regulation method and system for a photovoltaic-storage coupled inverter includes the following steps:

[0009] S1: Real-time acquisition of electrical parameters at the grid connection point via voltage and current sensors, including instantaneous values ​​of three-phase voltage and three-phase current at the grid connection point;

[0010] S2: Based on the collected electrical parameters, calculate the power quality parameters using the Fast Fourier Transform algorithm. The power quality parameters include at least three of the following: total harmonic distortion rate, current content of each harmonic from 3rd to 25th, voltage RMS deviation, grid frequency deviation, and power factor.

[0011] The formula for calculating the total harmonic distortion rate is as follows:

[0012] = 100%;

[0013] in, Total harmonic distortion (THD) for RMS value of subharmonic current This represents the effective value of the fundamental current.

[0014] S3: Compare the calculated power quality parameters with the preset threshold to determine whether there is a power quality exceeding the standard;

[0015] S4: If there is a problem of exceeding the standard, a collaborative control strategy is generated by taking into account the real-time output value of the photovoltaic power generation unit, the state of charge of the energy storage unit, and the specific type of power quality problem.

[0016] The specific collaborative control strategy is as follows:

[0017] When power quality issues are voltage or frequency deviations, the charging and discharging power of the energy storage unit is adjusted first. Active power is injected into or absorbed from the grid through the photovoltaic-storage coupled inverter to achieve voltage and frequency support. The active power adjustment amount satisfies the following formula:

[0018] ;

[0019] In the formula, This refers to the active power regulation. This is the voltage regulation coefficient, with a value ranging from 5-10kW / %. This is the frequency adjustment coefficient, with a value ranging from 100-200 kW / Hz. The percentage of voltage deviation. This is the frequency deviation value;

[0020] When the power quality problem is excessive harmonics or a low power factor, the photovoltaic-storage coupled inverter outputs a compensation current that is opposite in phase and equal in amplitude to the harmonic current, thereby achieving harmonic suppression and power factor correction. The target reactive power satisfies the following formula:

[0021] ;

[0022] In the formula, For target reactive power, This is the effective value of the voltage at the grid connection point. This is the effective value of the current at the grid connection point. It is the voltage phase angle;

[0023] S5: Based on the collaborative control strategy, generate a PWM drive signal to control the photovoltaic-storage coupled inverter to perform the corresponding power quality compensation operation.

[0024] Preferably, when formulating the collaborative control strategy, the constraint logic for the state of charge of the energy storage unit is as follows:

[0025] If the state of charge of the energy storage unit is lower than the preset lower limit and there is a power quality problem that requires the absorption of active power, the active power regulation depth will be limited, or the mode will be switched to output only reactive power / harmonic compensation current.

[0026] If the state of charge of the energy storage unit is higher than the preset upper limit and there is a power quality problem that requires the injection of active power, the energy storage unit will be controlled to absorb the excess active power first, reducing the state of charge of the energy storage unit to a safe range while completing the power quality regulation.

[0027] Preferably, in step S4, when the real-time output of the photovoltaic power generation unit is lower than 90% of its rated power, the photovoltaic-storage coupled inverter is controlled to operate at a reduced rate, reserving at least 10% of its rated capacity for power quality regulation. The derating range can be dynamically adjusted according to the degree of power quality exceeding the standard. The reserved capacity satisfies the following formula:

[0028] = (1- )+ ;

[0029] In the formula, To reserve capacity, The rated power of the inverter, This is the ratio of real-time photovoltaic power output to rated power. Additional capacity reserved for situations where power quality exceeds standards.

[0030] The power quality regulation system of the photovoltaic-storage coupled inverter includes a monitoring module, a calculation and analysis module, a collaborative control decision module, and an inverter control module;

[0031] The monitoring module consists of a high-precision voltage sensor and a current sensor, used to collect electrical parameters of the grid connection point in real time;

[0032] The calculation and analysis module is equipped with a fast Fourier transform algorithm and a parameter calculation unit, which is used to convert the electrical parameters collected by the monitoring module into power quality parameters, compare them with preset national standard thresholds, and output the result of exceeding the standard.

[0033] The collaborative control decision module is used to receive the out-of-range signal from the calculation and analysis module, read the real-time output of photovoltaic and the state of charge data of the energy storage unit, and generate a collaborative control strategy.

[0034] The collaborative control decision module includes a load forecasting unit, which uses an LSTM neural network to predict the load power change trend in the next 15 minutes and adjusts the photovoltaic and energy storage output power allocation in advance based on the forecast results, thereby advancing the response time of power quality regulation.

[0035] The inverter control module is used to receive strategy instructions from the collaborative control decision module, generate PWM drive signals, control the operation of IGBT power switching devices in the photovoltaic-storage coupling inverter, and perform power quality regulation operations.

[0036] Preferably, the collaborative control decision module has a built-in energy storage unit state of charge safety protection subroutine. When the state of charge of the energy storage unit is detected to be outside the 20%-80% safety range, the constraint logic is automatically triggered to prioritize the safety of the energy storage unit. The energy storage unit state of charge safety protection subroutine also includes an adaptive early warning function. When the rate of change of the state of charge of the energy storage unit is detected to be more than 10% within 5 minutes, an early warning signal is automatically triggered and the regulation power in the corresponding direction is reduced until the rate of change of the state of charge of the energy storage unit is ≤5%. After the early warning is lifted, the regulation capability is gradually restored.

[0037] The advantages of the embodiments of this application are:

[0038] By monitoring the grid status and internal system parameters in real time, the system dynamically matches the types of power quality problems to generate the optimal control strategy. It can adapt to different grid conditions and system operating states, avoid the limitations of fixed strategies, and eliminate the need for additional dedicated power quality compensation equipment such as APF and SVG. It can directly reuse the existing hardware resources of the photovoltaic-storage coupled inverter to achieve functional integration, significantly reduce system hardware investment, installation and operation and maintenance costs, and help the low-cost and large-scale application of distributed photovoltaics.

[0039] It can simultaneously address multiple power quality issues such as excessive harmonics, voltage deviation, frequency deviation, and low power factor, eliminating the need for multiple single-function regulation devices. This enhances the added value and grid-friendliness of the photovoltaic-storage system. The control strategy incorporates energy storage state-of-charge safety threshold constraints to prevent overcharging and discharging of energy storage units due to power quality regulation, effectively protecting the lifespan of energy storage batteries and ensuring long-term stable operation of the system.

[0040] Actively participate in power quality regulation of the power grid, stabilize voltage and frequency through active power support, optimize power waveform through reactive power / harmonic compensation, improve the stability and power supply quality of local distribution networks, and contribute to the construction of new power systems. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the power quality regulation method for the photovoltaic-storage coupled inverter of the present invention;

[0042] Figure 2 This is a schematic diagram of the power quality regulation system of the photovoltaic-storage coupled inverter of the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention 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 the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. In addition, for the sake of convenience, the terms "upper," "lower," "left," and "right" are equivalent to the upper, lower, left, and right directions of the accompanying drawings themselves, and the terms "first," "second," etc., are used for descriptive purposes and have no other special meaning.

[0044] This application provides a power quality regulation method and system for a photovoltaic-storage coupled inverter, which solves the problems in the prior art. By monitoring the grid status and internal system parameters in real time, it dynamically matches the power quality problem type to generate the optimal control strategy. It can adapt to different grid conditions and system operating states, avoid the limitations of fixed strategies, and eliminate the need for additional dedicated power quality compensation equipment such as APF and SVG. It directly reuses the existing hardware resources of the photovoltaic-storage coupled inverter to achieve functional integration, significantly reducing system hardware investment, installation and operation and maintenance costs, and helping the low-cost large-scale application of distributed photovoltaics.

[0045] It can simultaneously address multiple power quality issues such as excessive harmonics, voltage deviation, frequency deviation, and low power factor, eliminating the need for multiple single-function regulation devices. This enhances the added value and grid-friendliness of the photovoltaic-storage system. The control strategy incorporates energy storage state-of-charge safety threshold constraints to prevent overcharging and discharging of energy storage units due to power quality regulation, effectively protecting the lifespan of energy storage batteries and ensuring long-term stable operation of the system.

[0046] Actively participate in power quality regulation of the power grid, stabilize voltage and frequency through active power support, optimize power waveform through reactive power / harmonic compensation, improve the stability and power supply quality of local distribution networks, and contribute to the construction of new power systems.

[0047] The technical solution in this application is to solve the above problems, and the overall approach is as follows:

[0048] Example 1

[0049] This embodiment provides a power quality regulation method for a photovoltaic-storage coupled inverter, such as... Figure 1 As shown, it includes the following steps:

[0050] S1: Real-time acquisition of electrical parameters at the grid connection point via voltage and current sensors, including instantaneous values ​​of three-phase voltage and three-phase current at the grid connection point;

[0051] Furthermore, after the system starts up, the voltage and current sensors of the monitoring module collect the three-phase voltage and current signals at the grid connection point in real time. The sampled data is transmitted to the calculation and analysis module through high-speed AD conversion, and the data update frequency is 2kHz.

[0052] S2: Based on the collected electrical parameters, calculate the power quality parameters using the Fast Fourier Transform algorithm. The power quality parameters include at least three of the following: total harmonic distortion rate, current content of each harmonic from 3rd to 25th, voltage RMS deviation, grid frequency deviation, and power factor.

[0053] The formula for calculating the total harmonic distortion rate is as follows:

[0054] = 100%;

[0055] in, Total harmonic distortion (THD) for RMS value of subharmonic current This represents the effective value of the fundamental current.

[0056] S3: Compare the calculated power quality parameters with the preset threshold to determine whether there is a power quality exceeding the standard;

[0057] Furthermore, the calculation and analysis module compares the above parameters with preset thresholds and determines that there are three types of power quality problems: voltage deviation, frequency deviation, and harmonic exceedance. Then, it sends an exceedance trigger signal to the collaborative control decision module.

[0058] S4: If there is a problem of exceeding the standard, a collaborative control strategy is generated by taking into account the real-time output value of the photovoltaic power generation unit, the state of charge of the energy storage unit, and the specific type of power quality problem.

[0059] When formulating the coordinated control strategy, the constraint logic for the state of charge of the energy storage unit is as follows:

[0060] If the state of charge of the energy storage unit is lower than the preset lower limit and there is a power quality problem that requires the absorption of active power, the active power regulation depth will be limited, or the mode will be switched to output only reactive power / harmonic compensation current.

[0061] If the state of charge of the energy storage unit is higher than the preset upper limit and there is a power quality problem that requires the injection of active power, the energy storage unit will be controlled to absorb the excess active power first, reducing the state of charge of the energy storage unit to a safe range while completing the power quality regulation.

[0062] The specific collaborative control strategy is as follows:

[0063] When power quality issues are voltage or frequency deviations, the charging and discharging power of the energy storage unit is adjusted first. Active power is injected into or absorbed from the grid through the photovoltaic-storage coupled inverter to achieve voltage and frequency support. The active power adjustment amount satisfies the following formula:

[0064] ;

[0065] In the formula, This refers to the active power regulation. This is the voltage regulation coefficient, with a value ranging from 5-10kW / %. This is the frequency adjustment coefficient, with a value ranging from 100-200 kW / Hz. The percentage of voltage deviation. This is the frequency deviation value;

[0066] When the power quality problem is excessive harmonics or a low power factor, the photovoltaic-storage coupled inverter outputs a compensation current that is opposite in phase and equal in amplitude to the harmonic current, thereby achieving harmonic suppression and power factor correction. The target reactive power satisfies the following formula:

[0067] ;

[0068] In the formula, For target reactive power, This is the effective value of the voltage at the grid connection point. This is the effective value of the current at the grid connection point. It is the voltage phase angle;

[0069] When the real-time output of the photovoltaic power generation unit is lower than 90% of its rated power, the photovoltaic-storage coupled inverter is controlled to operate at a reduced rate, reserving at least 10% of the rated capacity for power quality regulation. The derating range can be dynamically adjusted according to the degree of power quality exceeding the standard. The reserved capacity satisfies the following formula:

[0070] = (1- )+ ;

[0071] In the formula, To reserve capacity, The rated power of the inverter, This is the ratio of real-time photovoltaic power output to rated power. Additional capacity reserved for situations where power quality exceeds standards.

[0072] S5: Based on the collaborative control strategy, generate a PWM drive signal to control the photovoltaic-storage coupled inverter to perform the corresponding power quality compensation operation.

[0073] Furthermore, the inverter control module receives strategy instructions and generates two PWM drive signals: one for controlling the active power regulation (15kW) of energy storage discharge, and the other for generating harmonic compensation current (4kW) and reactive power (4kW). After the two signals are combined, they drive the IGBT switching transistor to achieve power quality regulation. The system continuously monitors the grid connection point parameters. The collaborative control decision module determines that the power quality has returned to normal, instructs the inverter to exit the compensation mode and return to the normal grid-connected power generation state, the photovoltaic unit resumes MPPT tracking, and the energy storage unit operates according to the original charging and discharging plan.

[0074] Example 2

[0075] This embodiment provides a power quality regulation system for a photovoltaic-storage coupled inverter, such as... Figure 2 As shown, the power quality regulation system of the photovoltaic-storage coupled inverter includes a monitoring module, a calculation and analysis module, a collaborative control decision module, and an inverter control module;

[0076] The monitoring module consists of high-precision voltage and current sensors, used to collect electrical parameters at the grid connection point in real time;

[0077] Furthermore, a voltage sensor with an accuracy class of 0.2S (model: PT-10kV / 0.1kV) and a current sensor (model: CT-0-1000A / 5A) are used. The sampling frequency is set to 20kHz and the sampling period is 50μs. The instantaneous values ​​of the three-phase voltage (range: 0-12kV) and the instantaneous values ​​of the three-phase current (range: 0-1200A) at the grid connection point A, B, and C are collected in real time. The collected data is transmitted to the calculation and analysis module through an RS485 communication interface with a data transmission rate of 115200bps and a transmission delay of ≤10ms.

[0078] The calculation and analysis module is equipped with a fast Fourier transform algorithm and a parameter calculation unit, which is used to convert the electrical parameters collected by the monitoring module into power quality parameters, compare them with the preset national standard threshold, and output the result of exceeding the standard.

[0079] Furthermore, a hardware platform is built based on the ARM Cortex-A9 processor, incorporating a Fast Fourier Transform (FFT) algorithm module and a power quality parameter calculation unit. The preset national standard thresholds for power quality are set according to the standard, specifically including: Total Harmonic Distortion (THD) ≤ 5%, 3rd harmonic current content ≤ 2.4%, 5th harmonic current content ≤ 3.2%, effective voltage deviation ±7%, grid frequency deviation ±0.2Hz, and power factor ≥ 0.95.

[0080] The collaborative control decision module is used to receive the out-of-limit signal from the calculation and analysis module, read the real-time output of photovoltaic and the state of charge data of the energy storage unit, and generate a collaborative control strategy.

[0081] The collaborative control decision module includes a load forecasting unit, which uses an LSTM neural network to predict the load power change trend in the next 15 minutes and adjusts the photovoltaic and energy storage output power allocation in advance based on the forecast results, thereby advancing the response time of power quality regulation.

[0082] Furthermore, the collaborative control strategy dynamically allocates the adjustment weights of each energy source based on real-time operating conditions:

[0083] When the photovoltaic output is sufficient and the state of charge of the energy storage unit is within a safe range, the remaining photovoltaic capacity is used first to perform reactive power compensation or harmonic suppression to reduce energy storage charging and discharging losses.

[0084] When photovoltaic output fluctuates significantly, energy storage provides rapid transient adjustment, while photovoltaic power undertakes the task of stabilizing the base load.

[0085] When the state of charge of the energy storage unit approaches the safety threshold, the strategy will automatically switch to the "photovoltaic-led + grid-assisted" mode, and the grid will provide short-term support to prevent the energy storage from being overcharged or over-discharged.

[0086] The collaborative control strategy incorporates a machine learning module to optimize decisions by continuously learning from historical data.

[0087] Sub-models are established for typical operating conditions in different seasons, such as high photovoltaic output in summer and high load in winter, and the regulation priority of photovoltaic / energy storage is automatically adjusted.

[0088] For recurring similar problems, the optimal solution is learned through reinforcement learning, which shortens the subsequent response time and enables the strategy to dynamically adapt to diverse scenarios, thus solving the problem of poor adaptability of traditional fixed strategies in complex power grid environments.

[0089] A dual-layer constraint mechanism integrating equipment status and power quality requirements;

[0090] Inner constraints: Hard limits are set on equipment parameters such as the state of charge of the energy storage unit, the maximum derating of photovoltaics, and the overload capacity of the inverter to ensure that the adjustment process does not damage the hardware;

[0091] Outer constraints: Based on the national standards for power quality, the optimization algorithm optimizes the power quality indicators while satisfying the inner constraints.

[0092] When harmonic exceedances are detected and the state of charge of the energy storage unit has reached 90%, the strategy will prioritize the use of the remaining photovoltaic capacity and combine it with grid-side compensation. This avoids overcharging of the energy storage and achieves compliance through multi-path coordination. This constraint mechanism, which emphasizes both safety and effectiveness, is an important improvement over traditional strategies.

[0093] The inverter control module receives strategy instructions from the collaborative control decision module, generates PWM drive signals, controls the operation of IGBT power switching devices in the photovoltaic-storage coupled inverter, and performs power quality regulation operations.

[0094] The collaborative control decision module has a built-in subroutine for the safety protection of the energy storage unit's state of charge. When the state of charge of the energy storage unit is detected to be outside the safe range of 20%-80%, the constraint logic is automatically triggered to prioritize the safety of the energy storage unit. The subroutine for the safety protection of the energy storage unit's state of charge also includes an adaptive early warning function. When the rate of change of the energy storage unit's state of charge is detected to be more than 10% within 5 minutes, an early warning signal is automatically triggered and the regulation power in the corresponding direction is reduced until the rate of change of the energy storage unit's state of charge is ≤5%. After the early warning is lifted, the regulation capability is gradually restored.

[0095] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for power quality regulation of a photovoltaic-storage coupled inverter, characterized in that, Includes the following steps: S1: Real-time acquisition of electrical parameters at the grid connection point via voltage and current sensors; S2: Based on the collected electrical parameters, calculate the power quality parameters using the Fast Fourier Transform algorithm; S3: Compare the calculated power quality parameters with the preset threshold to determine whether there is a power quality exceeding the standard; S4: If there is a problem of exceeding the standard, a collaborative control strategy is generated by taking into account the real-time output value of the photovoltaic power generation unit, the state of charge of the energy storage unit, and the specific type of power quality problem. The specific collaborative control strategy is as follows: When power quality issues are voltage or frequency deviations, the charging and discharging power of the energy storage unit is adjusted first. Active power is injected into or absorbed from the grid through the photovoltaic-storage coupled inverter to achieve voltage and frequency support. The active power adjustment amount satisfies the following formula: ； In the formula, This refers to the active power regulation. This is the voltage regulation coefficient, with a value ranging from 5-10kW / %. This is the frequency adjustment coefficient, with a value ranging from 100-200 kW / Hz. The percentage of voltage deviation. This is the frequency deviation value; When the power quality problem is excessive harmonics or a low power factor, the photovoltaic-storage coupled inverter outputs a compensation current that is opposite in phase and equal in amplitude to the harmonic current, thereby achieving harmonic suppression and power factor correction. The target reactive power satisfies the following formula: ； In the formula, For target reactive power, This is the effective value of the voltage at the grid connection point. This is the effective value of the current at the grid connection point. It is the voltage phase angle; S5: Based on the collaborative control strategy, generate a PWM drive signal to control the photovoltaic-storage coupled inverter to perform the corresponding power quality compensation operation.

2. The power quality regulation method for a photovoltaic-storage coupled inverter according to claim 1, characterized in that, The electrical parameters in step S1 include the instantaneous values ​​of the three-phase voltage and the instantaneous values ​​of the three-phase current at the grid connection point.

3. The power quality regulation method for a photovoltaic-storage coupled inverter according to claim 1, characterized in that, The power quality parameters in step S2 include at least three of the following: total harmonic distortion, current content of each harmonic from the 3rd to the 25th order, voltage RMS deviation, grid frequency deviation, and power factor.

4. The power quality regulation method for a photovoltaic-storage coupled inverter according to claim 3, characterized in that, When formulating the collaborative control strategy, the constraint logic for the state of charge of the energy storage unit is as follows: If the state of charge of the energy storage unit is lower than the preset lower limit and there is a power quality problem that requires the absorption of active power, the active power regulation depth will be limited, or the mode will be switched to output only reactive power / harmonic compensation current. If the state of charge of the energy storage unit is higher than the preset upper limit and there is a power quality problem that requires the injection of active power, the energy storage unit will be controlled to absorb the excess active power first, reducing the state of charge of the energy storage unit to a safe range while completing the power quality regulation.

5. The power quality regulation method for a photovoltaic-storage coupled inverter according to claim 1, characterized in that, In step S4, when the real-time output of the photovoltaic power generation unit is lower than 90% of its rated power, the photovoltaic-storage coupled inverter is controlled to operate at a reduced rate, reserving at least 10% of its rated capacity for power quality regulation. The derating range can be dynamically adjusted according to the degree of power quality exceeding the standard. The reserved capacity satisfies the following formula: = (1- )+ ； In the formula, To reserve capacity, The rated power of the inverter, This is the ratio of real-time photovoltaic power output to rated power. Additional capacity reserved for situations where power quality exceeds standards.

6. The power quality regulation method for a photovoltaic-storage coupled inverter according to claim 3, characterized in that, The formula for calculating the total harmonic distortion rate in step S2 is as follows: = 100%； in, Total harmonic distortion (THD) for RMS value of subharmonic current This represents the effective value of the fundamental current.

7. A power quality conditioning system for implementing the method of any one of claims 1-6 in a photovoltaic-storage coupled inverter, characterized in that, It includes a monitoring module, a calculation and analysis module, a collaborative control and decision-making module, and an inverter control module; The monitoring module consists of a high-precision voltage sensor and a current sensor, used to collect electrical parameters of the grid connection point in real time; The calculation and analysis module is equipped with a fast Fourier transform algorithm and a parameter calculation unit, which is used to convert the electrical parameters collected by the monitoring module into power quality parameters, compare them with preset national standard thresholds, and output the result of exceeding the standard. The collaborative control decision module is used to receive the out-of-range signal from the calculation and analysis module, read the real-time output of photovoltaic and the state of charge data of the energy storage unit, and generate a collaborative control strategy. The inverter control module is used to receive strategy instructions from the collaborative control decision module, generate PWM drive signals, control the operation of IGBT power switching devices in the photovoltaic-storage coupling inverter, and perform power quality regulation operations.

8. The power quality conditioning system for a photovoltaic-storage coupled inverter according to claim 7, characterized in that, The collaborative control decision module includes a load prediction unit, which uses an LSTM neural network to predict the load power change trend in the next 15 minutes and adjusts the photovoltaic and energy storage output power allocation in advance based on the prediction results, thereby advancing the response time of power quality regulation.

9. The power quality conditioning system for a photovoltaic-storage coupled inverter according to claim 7, characterized in that, The collaborative control decision module has a built-in subroutine for the safety protection of the energy storage unit's state of charge. When the state of charge of the energy storage unit is detected to be outside the safe range of 20%-80%, the constraint logic is automatically triggered to prioritize the safety of the energy storage unit.

10. The power quality conditioning system for a photovoltaic-storage coupled inverter according to claim 9, characterized in that, The energy storage unit's state of charge safety protection subroutine also includes an adaptive early warning function. When the rate of change of the energy storage unit's state of charge exceeds 10% within 5 minutes, an early warning signal is automatically triggered and the regulation power in the corresponding direction is reduced until the rate of change of the energy storage unit's state of charge is ≤5%. After the early warning is lifted, the regulation capability is gradually restored.

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