A dynamic damping control method for photovoltaic storage system based on DC capacitor energy

Abstract

The present invention specifically discloses a method for dynamic damping control of a photovoltaic storage system based on DC capacitor energy, which relates to the field of new energy technology. The method first obtains the DC bus voltage value, photovoltaic output voltage and current, energy storage battery voltage and current, LC filter inductor current, and grid connection point voltage and current in the current photovoltaic storage system; then adjusts the photovoltaic and energy storage systems to operate in coordination, the photovoltaic system uses the perturbation observation method to achieve maximum power point tracking, and the energy storage system stabilizes the DC bus voltage through a voltage-current dual closed loop; then, based on the dynamic damping control strategy of DC capacitor energy, the difference between the actual energy of the DC capacitor and the reference value is introduced into the active control loop of the network control through the DC damping coefficient; finally, the network control is performed in combination with the inverter virtual synchronous generator control technology. This method effectively utilizes existing hardware resources, does not require complex algorithms, significantly improves the dynamic performance of the system, and has strong adaptability and broad application prospects.

Description

Technical Field

[0001] The present invention relates to the field of new energy technology, and in particular to a method for controlling dynamic damping of a photovoltaic storage system based on DC capacitor energy. Background Art

[0002] With the rapid development of photovoltaic (PV) power generation technology, especially with the widespread application of large-scale PV power generation systems, the stability and dynamic response capabilities of the power grid are facing unprecedented challenges. As an important renewable energy source, PV power generation is characterized by significant intermittency and volatility. This results in a significant adverse impact on the frequency, power balance, and voltage stability of the power grid during the process of large-scale PV power generation being connected to the grid. Specifically, the output power of PV power generation is affected by factors such as weather and sunlight, and exhibits volatility and instability. When widely integrated into the power grid, it often causes fluctuations in grid frequency and power, which in turn affects the voltage stability of the grid. These issues have, to a certain extent, restricted the reliability of PV power generation systems and the stable operation of the power grid.

[0003] To address this issue, grid-forming control (GFM) has been widely used as an effective technical approach. Grid-forming control can be equivalent to a constant voltage source, providing the necessary frequency and voltage support to the grid, thereby ensuring stable grid operation. However, when responding to sudden grid events, GFM often requires additional energy support. This is especially true when grid load fluctuates dramatically, as the power output of the photovoltaic system may not be sufficient to meet sudden grid demands. Therefore, battery energy storage systems (BES) are often introduced as energy reserves to ensure additional energy support in the event of sudden grid fluctuations, ensuring stable grid operation.

[0004] In order to further enhance the photovoltaic-energy storage system's ability to support the power grid, its coordinated control needs to be optimized to ensure its stable operation in complex power grid environments. Although existing photovoltaic-energy storage system control technologies have been applied to a certain extent, they still have some obvious defects when facing complex working conditions such as grid load fluctuations. Specifically, traditional control strategies usually use a fixed damping coefficient to improve the dynamic response performance of the system. However, this strategy lacks flexibility when facing changes in the dynamic characteristics of the power grid and has poor adaptability under different power grid conditions. In particular, when the grid load fluctuates violently, the fixed damping coefficient often cannot respond in a timely and effective manner, resulting in system power overshoot and even system instability. In addition, traditional control methods often ignore the potential of DC capacitors as energy transmission components and fail to fully utilize the information stored in them for active damping adjustment, which limits the stability and flexibility of the system in dynamic response. Summary of the Invention

[0005] The purpose of the present invention is to propose a dynamic damping control method for a photovoltaic storage system based on DC capacitor energy, give full play to the energy characteristics of the DC capacitor in the photovoltaic storage system, enhance the dynamic response capability of the system, achieve rapid response to grid load fluctuations, improve the adaptability of the system in complex grid environments, and ensure efficient and stable operation of the photovoltaic storage system.

[0006] To achieve the above objectives, the present invention proposes a method for controlling dynamic damping of a photovoltaic storage system based on DC capacitor energy, which comprises the following steps:

[0007] Step S1, obtaining the DC bus voltage value, photovoltaic output voltage and current, energy storage battery voltage and current, LC filter inductor current, and grid connection point voltage and current in the current photovoltaic storage system;

[0008] Step S2: Regulating the photovoltaic system and the energy storage system for coordinated operation, wherein the photovoltaic system uses a disturbance observation method to achieve maximum power point tracking control, and the energy storage system stabilizes the DC bus voltage through voltage-current dual closed-loop control;

[0009] Step S3: using a dynamic damping control strategy based on DC capacitor energy to improve the system's responsiveness, specifically: calculating the difference between the actual energy of the DC capacitor and the reference value, and introducing the difference into the active power control loop of the network control through the DC damping coefficient;

[0010] Step S4: Based on steps S2 and S3, the inverter virtual synchronous generator control technology is combined to perform network control to achieve stable operation of the photovoltaic storage system in strong and weak grid environments.

[0011] Preferably, in step S2, the photovoltaic system adopts the perturbation observation method to implement maximum power point tracking (MPPT) control, and the specific steps are as follows:

[0012] Step S211: Collect the voltage at the photovoltaic cell terminal and current Signal, input maximum power point tracking MPPT control;

[0013] Step S212: Based on the collected photovoltaic voltage and current , perform maximum power point tracking MPPT control, calculate and output voltage reference value ;

[0014] Step S213: Set the voltage reference value The actual output voltage of photovoltaic Perform comparison to generate a voltage error signal;

[0015] Step S214: input the voltage error signal into a proportional-integral PI controller, and output a duty cycle signal for adjusting the photovoltaic converter;

[0016] Step S215: Input the duty cycle signal of the photovoltaic converter into the pulse width modulation module PWM to generate a PWM switching signal. .

[0017] Preferably, in step S212, maximum power point tracking (MPPT) control is performed, and the specific steps are as follows:

[0018] Step S2121: Calculate the increments of power and voltage, and determine the relationship between the increments of power and voltage based on the current photovoltaic output power and voltage values;

[0019] Step S2122: Adjust the operating voltage according to the sign of the power increment. If the power increment is positive, increase the operating voltage of the photovoltaic cell; if the power increment is negative, reduce the operating voltage of the photovoltaic cell; if the power increment is zero, keep the current voltage unchanged.

[0020] Step S2123: Adjust the operating voltage of the photovoltaic cell according to the determination result of the increment sign until the system stabilizes at the maximum power point;

[0021] Step S2124: continuously collect the output parameters of the photovoltaic cells and repeat the power and voltage disturbance observation operation to ensure that the photovoltaic system always operates at the maximum power point.

[0022] Preferably, in step S2, the energy storage system stabilizes the DC bus voltage through voltage-current dual closed-loop control, and the specific steps of the control process are as follows:

[0023] Step S221: Collect the current DC bus voltage value and compare it with the DC voltage reference value to obtain a voltage error signal. The formula is as follows:

[0024] ;

[0025] in, is the voltage error signal, is the DC voltage reference value, v dc is the current DC bus voltage value;

[0026] Step S222: Input the voltage error signal into the proportional-integral PI controller and output the current reference instruction. , the formula is as follows:

[0027] ;

[0028] in, , denote the voltage loop proportional and integral gains respectively,s is the Laplace operator;

[0029] Step S223: compare the current reference command with the actual feedback current value. By comparison, the current error signal is obtained, and the current error signal is input into the proportional-integral PI controller to output the duty cycle signal. The formula is as follows:

[0030] ;

[0031] in, is the duty cycle signal, , Represent the current loop proportional and integral gains respectively;

[0032] Step S224: Input the duty cycle signal into the pulse width modulation generation module PWM to generate a PWM switching signal to drive the energy storage converter. .

[0033] Preferably, in step S3, a dynamic damping control strategy based on DC capacitor energy is adopted to improve the responsiveness and stability of the system. The specific steps are as follows:

[0034] Step S31: Calculate the actual DC capacitor energy E dc , the formula is as follows:

[0035] ;

[0036] in, is the current DC bus current value, t For the current moment;

[0037] Step S32: Calculate the difference between the DC capacitor energy reference value and the actual DC capacitor energy , the formula is as follows:

[0038] ;

[0039] in, is the DC capacitor energy reference value;

[0040] Step S33: The energy difference is converted into DC damping coefficient. D c Introduced into the active power control loop of network control, the calculation formula is as follows:

[0041] ;

[0042] in, is the active power reference value, Output active power for the inverter, is the damping coefficient of the system, and Represent the rated angular frequency and actual angular frequency of the power grid respectively, is the DC capacitor damping coefficient, J is the moment of inertia of the system;

[0043] Preferably, in step S4, the inverter adopts virtual synchronous generator control technology VSG for network control, and the calculation formula is as follows:

[0044] ;

[0045] in, is the terminal voltage amplitude, and V o are the rated phase voltage amplitude and actual output phase voltage amplitude of the power grid respectively, K and D q are the proportional coefficient and reactive droop coefficient respectively, is the reactive power reference value, is the reactive power.

[0046] Therefore, the present invention proposes a method for controlling dynamic damping of a photovoltaic storage system based on DC capacitor energy, which has the following beneficial effects:

[0047] (1) The present invention can improve the dynamic response capability of the photovoltaic storage system, effectively reduce power overshoot and adjustment time, and introduce the energy difference stored in the DC capacitor into the AC side through the damping coefficient. It can effectively suppress power overshoot when the load suddenly changes, and ensure the smooth transient overload output.

[0048] (2) The present invention realizes the stable operation of the photovoltaic storage system under different grid conditions (including weak and strong grid environments) through the coordinated control of the photovoltaic system, energy storage system and inverter. It not only improves the response speed and dynamic stability of the system, but also significantly enhances its adaptability to grid load fluctuations, ensuring the high efficiency and reliability of the photovoltaic storage system in a complex grid environment.

[0049] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of a flow chart of a method for controlling dynamic damping of a photovoltaic storage system based on DC capacitor energy according to the present invention;

[0051] Figure 2 This is a structural diagram of a common DC bus photovoltaic storage grid-connected system according to a method for controlling dynamic damping of a photovoltaic storage system based on DC capacitor energy of the present invention;

[0052] Figure 3 Schematic diagram of a circuit for controlling a photovoltaic system based on maximum power point tracking in the present invention;

[0053] Figure 4 Schematic diagram of the circuit for voltage and current dual-loop control of the energy storage system in the present invention;

[0054] Figure 5 Schematic diagram of the circuit of the DC capacitor dynamic damping control strategy in the present invention;

[0055] Figure 6 A schematic diagram of a circuit for controlling the network construction of the inverter in the present invention;

[0056] Figure 7 Schematic diagram of simulation results before executing the DC capacitor dynamic damping control method under a strong network in an embodiment of the present invention; wherein, Figure 7 (a) is a schematic diagram of the active power curve before the DC capacitor dynamic damping control method is implemented under strong grid conditions. Figure 7 (b) is a schematic diagram of the DC bus voltage curve before the DC capacitor dynamic damping control method is implemented under strong grid conditions. Figure 7 (c) is a schematic diagram of the energy storage power curve before the DC capacitor dynamic damping control method is implemented under strong grid conditions;

[0057] Figure 8 Schematic diagram of simulation results after executing the DC capacitor dynamic damping control method under a strong network in an embodiment of the present invention; wherein, Figure 8 (a) is a schematic diagram of the active power curve after the DC capacitor dynamic damping control method is implemented under strong grid conditions. Figure 8 (b) is a schematic diagram of the DC bus voltage curve after the DC capacitor dynamic damping control method is implemented under strong grid conditions. Figure 8 (c) is a schematic diagram of the energy storage power curve after the DC capacitor dynamic damping control method is implemented under strong grid conditions;

[0058] Figure 9 Schematic diagram of simulation results before executing the DC capacitor dynamic damping control method under weak network conditions in an embodiment of the present invention; wherein, Figure 9 (a) is a schematic diagram of the active power curve before the DC capacitor dynamic damping control method is implemented under weak grid conditions. Figure 9 (b) is a schematic diagram of the DC bus voltage curve before the DC capacitor dynamic damping control method is implemented under weak grid conditions. Figure 9 (c) is a schematic diagram of the energy storage power curve before the DC capacitor dynamic damping control method is implemented under weak grid conditions;

[0059] Figure 10 Schematic diagram of simulation results after executing the DC capacitor dynamic damping control method under weak network conditions in an embodiment of the present invention; wherein, Figure 10(a) is a schematic diagram of the active power curve after the DC capacitor dynamic damping control method is implemented under weak grid conditions. Figure 10 (b) is a schematic diagram of the DC bus voltage curve after the DC capacitor dynamic damping control method is implemented under weak grid conditions. Figure 10 (c) in the figure is a schematic diagram of the energy storage power curve after implementing the DC capacitor dynamic damping control method under weak grid conditions. DETAILED DESCRIPTION

[0060] To make the technical solutions, advantages, and objectives of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. The described embodiments are part of the embodiments of the present invention, not all of them. Based on the described 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.

[0061] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0062] like Figure 1-2 As shown, the present invention provides a method for dynamic damping control of a photovoltaic storage system based on DC capacitor energy, in which the photovoltaic and energy storage systems are connected to the DC bus through their respective converters. Subsequently, the inverter converts DC power into AC power and connects it to the grid through an LC filter. Among them, the advantages of the common DC bus topology are: improving system efficiency, simplifying control strategies, reducing costs, enhancing system reliability, and facilitating expansion and integration. Through the DC bus, photovoltaic and energy storage systems can work together more efficiently and reduce energy conversion losses; at the same time, it simplifies the design of the control system, reduces coordination complexity, and facilitates precise energy management. This topology also reduces hardware costs and installation and maintenance complexity, improves the overall reliability of the system, and provides greater flexibility for later system expansion; the specific steps are as follows:

[0063] S1. Obtain the current DC bus voltage value, photovoltaic output voltage and current, energy storage battery voltage and current, LC filter inductor current, and grid connection point voltage and current in the solar-storage system;

[0064] S2, regulating the coordinated operation of the photovoltaic system and the energy storage system;

[0065] like Figure 3 As shown in the figure, by collecting photovoltaic voltage and current, the maximum power point tracking is performed through the perturbation observation method to generate a photovoltaic reference voltage, and the photovoltaic reference voltage is tracked by the PI controller to generate a photovoltaic duty cycle signal. The specific steps are as follows:

[0066] S211, collect the voltage of photovoltaic cell terminal and current Signal, input maximum power point tracking MPPT control;

[0067] S212, according to the collected photovoltaic voltage and current , perform maximum power point tracking MPPT control, calculate and output voltage reference value , the specific steps are as follows:

[0068] S2121. Calculate the increments of power and voltage, and determine the relationship between the increments of power and voltage based on the current photovoltaic output power and voltage values;

[0069] S2122. Adjust the operating voltage according to the sign of the power increment. If the power increment is positive, increase the operating voltage of the photovoltaic cell; if the power increment is negative, decrease the operating voltage of the photovoltaic cell; if the power increment is zero, keep the current voltage unchanged;

[0070] S2123. Adjust the operating voltage of the photovoltaic cell according to the determination result of the increment sign until the system stabilizes at the maximum power point;

[0071] S2124. Continuously collect the output parameters of the photovoltaic cells and repeat the power and voltage disturbance observation operations to ensure that the photovoltaic system always operates at the maximum power point.

[0072] S213, the voltage reference value The actual output voltage of photovoltaic Perform comparison to generate a voltage error signal;

[0073] S214, inputting the voltage error signal into a proportional-integral PI controller, and outputting a duty cycle signal for adjusting the photovoltaic converter;

[0074] S215: Inputting the duty cycle signal of the photovoltaic converter into the pulse width modulation module PWM to generate a PWM switching signal .

[0075] like Figure 4 As shown in the figure, the DC bus voltage is subtracted from the reference value, and the voltage loop PI is used to adjust the output current reference instruction. The current loop PI is then used to adjust the output duty cycle signal, and finally a PWM signal is generated to drive the energy storage converter. The specific steps are as follows:

[0076] S221. Collect the current DC bus voltage value and compare it with the DC voltage reference value to obtain a voltage error signal. The formula is as follows:

[0077] ;

[0078] in, is the voltage error signal, is the DC voltage reference value, is the current DC bus voltage value;

[0079] S222: Input the voltage error signal into the proportional-integral PI controller and output the current reference instruction. , the formula is as follows:

[0080] ;

[0081] in, , denote the voltage loop proportional and integral gains respectively, s is the Laplace operator;

[0082] S223, the current reference command and the actual feedback current value By comparison, the current error signal is obtained, and the current error signal is input into the proportional-integral PI controller to output the duty cycle signal. The formula is as follows:

[0083] ;

[0084] in, is the duty cycle signal, , Represent the current loop proportional and integral gains respectively;

[0085] S224: Input the duty cycle signal into the pulse width modulation generation module PWM to generate a PWM switching signal for driving the energy storage converter. .

[0086] S3, such as Figure 5 As shown, let the capacitance energy deviation be normalized by a coefficient D c Introduced into the active power control loop of the network, according to the given active power reference value P ref , combined with the actual angular frequency of the power grid , rated angular frequency , system moment of inertia J , damping coefficient D p and the voltage phase angle The specific steps are as follows:

[0087] S31. Calculate the actual DC capacitor energy E dc , the formula is as follows:

[0088] ;

[0089] in, is the current DC bus current value,t For the current moment;

[0090] S32. Calculate the difference between the DC capacitor energy reference value and the actual DC capacitor energy , the formula is as follows:

[0091] ;

[0092] in, is the DC capacitor energy reference value;

[0093] S33, the energy difference is converted into DC damping coefficient D c Introduced into the active power control loop of network control, the calculation formula is as follows:

[0094] ;

[0095] in, is the active power reference value, Output active power for the inverter, is the damping coefficient of the system, and Represent the rated angular frequency and actual angular frequency of the power grid respectively, is the DC capacitor damping coefficient, J is the moment of inertia of the system;

[0096] S4. Based on steps S2 and S3, grid control is performed in combination with the inverter virtual synchronous generator control technology to achieve stable operation of the photovoltaic storage system in strong and weak grid environments;

[0097] like Figure 6 As shown, the inverter uses virtual synchronous generator control technology VSG for network control. The calculation formula is as follows:

[0098] ;

[0099] in, is the terminal voltage amplitude, and V o are the rated phase voltage amplitude and actual output phase voltage amplitude of the power grid respectively, K and D q are the proportional coefficient and reactive droop coefficient respectively, is the reactive power reference value, is the reactive power.

[0100] According to the rated phase voltage amplitude of the power grid and the actual output phase voltage amplitude V o, as well as the proportional coefficient K and reactive droop coefficient D q This control strategy simulates the characteristics of synchronous generators and can provide inertia support power in the event of grid failure or disturbance, ensuring grid frequency stability. It effectively improves the system's ability to support and regulate grid voltage and frequency, enhances the adaptability and compatibility of the solar-storage system and the grid, and ensures stable operation under different grid operating conditions.

[0101] like Figure 7-8 As shown in the figure, under strong grid conditions (SCR=9), after adopting the DC capacitor dynamic damping control method of the present invention, Figure 7 (a) and Figure 8 Compared with (a), the active power overshoot is reduced from 1.3kW to 0.6kW, and the regulation time is reduced from 1250ms to 260ms. Figure 7 (b) and Figure 8 Compared with (b), the DC bus voltage deviation is reduced from 23V to 15V; Figure 7 (c) and Figure 8 Compared with (c) in FIG, the overshoot of the energy storage battery power is reduced from 1.8kW to 0.6kW. The present invention improves the dynamic performance of the system while ensuring the stability of the system.

[0102] like Figure 9-10 As shown in Figure 2, under weak grid conditions (SCR=1.5), the grid control is not easy to stabilize due to its own voltage source characteristics. Figure 9 (a) and Figure 10 Compared with (a), the active power overshoot is reduced from 0.1kW to 0kW, and the regulation time is reduced from 600ms to 500ms. Figure 9 (b) and Figure 10 Compared with (b), the DC bus voltage deviation is reduced from 6V to 4V; Figure 9 (c) and Figure 10 Compared to (c) in Figure 1, the energy storage battery power overshoot is reduced from 0.2kW to 0kW. This comparison shows that the proposed DC capacitor dynamic damping control method can maintain stable system operation even under weak grid conditions, while also improving its dynamic control capabilities and adaptability to various grid environments.

[0103] It is worth noting that the contents not elaborated in detail in the present invention are all prior art and are well known to those skilled in the art.

[0104] Therefore, the present invention provides a dynamic damping control method for a photovoltaic storage system based on DC capacitor energy. By introducing capacitor power difference and damping coefficient, the system response is improved without the need for complex algorithms. It can utilize existing hardware resources, reduce power overshoot and shorten response time under strong power grids, and maintain system stability under weak power grids. It has strong adaptability and broad application prospects.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for controlling dynamic damping of a photovoltaic storage system based on DC capacitor energy, characterized in that: Here are the steps: Step S1, obtaining the DC bus voltage value, photovoltaic output voltage and current, energy storage battery voltage and current, LC filter inductor current, and grid connection point voltage and current in the current photovoltaic storage system; Step S2: Regulating the photovoltaic system and the energy storage system for coordinated operation, wherein the photovoltaic system uses a disturbance observation method to achieve maximum power point tracking control, and the energy storage system stabilizes the DC bus voltage through voltage-current dual closed-loop control; Step S3: Using a dynamic damping control strategy based on DC capacitor energy to improve the system's responsiveness, specifically: calculating the difference between the actual DC capacitor energy and the reference value, and introducing the difference into the active power control loop of the network control through the DC damping coefficient; wherein, using a dynamic damping control strategy based on DC capacitor energy to improve the system's responsiveness and stability, the specific steps are as follows: Step S31: Calculate the actual DC capacitor energy , the formula is as follows: ； in, is the current DC bus current value, For the current moment; Step S32: Calculate the difference between the DC capacitor energy reference value and the actual DC capacitor energy , the formula is as follows: ； in, is the DC capacitor energy reference value; Step S33: The energy difference is converted into DC damping coefficient. Introduced into the active power control loop of network control, the calculation formula is as follows: ； in, is the active power reference value, Output active power to the inverter, is the damping coefficient of the system, and Represent the rated angular frequency and actual angular frequency of the power grid respectively, is the DC capacitor damping coefficient, is the moment of inertia of the system; Step S4: Based on steps S2 and S3, the inverter virtual synchronous generator control technology is combined to perform network control to achieve stable operation of the photovoltaic storage system in strong and weak grid environments.

2. The method for controlling dynamic damping of a photovoltaic storage system based on DC capacitor energy according to claim 1, characterized in that: In step S2, the photovoltaic system uses the disturbance observation method to implement maximum power point tracking (MPPT) control. The specific steps are as follows: Step S211: Collect the voltage at the photovoltaic cell terminal and current Signal, input maximum power point tracking MPPT control; Step S212: Based on the collected photovoltaic voltage and current , perform maximum power point tracking MPPT control, calculate and output voltage reference value ; Step S213: Set the voltage reference value The actual output voltage of photovoltaic Perform comparison to generate a voltage error signal; Step S214: input the voltage error signal into a proportional-integral PI controller, and output a duty cycle signal for adjusting the photovoltaic converter; Step S215: Input the duty cycle signal of the photovoltaic converter into the pulse width modulation module PWM to generate a PWM switching signal. .

3. The method for controlling dynamic damping of a photovoltaic storage system based on DC capacitor energy according to claim 2, characterized in that: In step S212, maximum power point tracking (MPPT) control is performed. The specific steps are as follows: Step S2121: Calculate the increments of power and voltage, and determine the relationship between the increments of power and voltage based on the current photovoltaic output power and voltage values; Step S2122: Adjust the operating voltage according to the sign of the power increment. If the power increment is positive, increase the operating voltage of the photovoltaic cell; if the power increment is negative, reduce the operating voltage of the photovoltaic cell; if the power increment is zero, keep the current voltage unchanged. Step S2123: Adjust the operating voltage of the photovoltaic cell according to the determination result of the increment sign until the system stabilizes at the maximum power point; Step S2124: continuously collect the output parameters of the photovoltaic cells and repeat the power and voltage disturbance observation operation to ensure that the photovoltaic system always operates at the maximum power point.

4. The method for controlling dynamic damping of a photovoltaic storage system based on DC capacitor energy according to claim 1, characterized in that: In step S2, the energy storage system stabilizes the DC bus voltage through voltage-current dual closed-loop control. The specific steps of the control process are as follows: Step S221: Collect the current DC bus voltage value and compare it with the DC voltage reference value to obtain a voltage error signal. The formula is as follows: ； in, is the voltage error signal, is the DC voltage reference value, is the current DC bus voltage value; Step S222: Input the voltage error signal into the proportional-integral PI controller and output the current reference instruction. , the formula is as follows: ； in, , denote the voltage loop proportional and integral gains respectively, is the Laplace operator; Step S223: compare the current reference command with the actual feedback current value. By comparison, the current error signal is obtained, and the current error signal is input into the proportional-integral PI controller to output the duty cycle signal. The formula is as follows: ； in, is the duty cycle signal, , Represent the current loop proportional and integral gains respectively; Step S224: Input the duty cycle signal into the pulse width modulation generation module PWM to generate a PWM switching signal to drive the energy storage converter. .

5. The method for controlling dynamic damping of a photovoltaic storage system based on DC capacitor energy according to claim 1, characterized in that: In step S4, the inverter uses the virtual synchronous generator control technology VSG to perform grid control. The calculation formula is as follows: ； in, is the terminal voltage amplitude, and are the rated phase voltage amplitude and actual output phase voltage amplitude of the power grid respectively, and are the proportional coefficient and reactive droop coefficient respectively, is the reactive power reference value, is the reactive power.

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