Distributed optical storage system voltage regulation method and system

Abstract

The invention discloses a distributed optical storage system voltage regulation method and system, and relates to the technical field of voltage stability control of a photovoltaic power generation system, and the method comprises the following steps: obtaining irradiation intensity and environment temperature data needed by power generation of a distributed optical storage system; adjusting the output end voltage of the photovoltaic unit based on a disturbance control method to realize maximum power point tracking control; acquiring load power requirements and direct-current bus voltage data of the optical storage grid-connected system in the common direct-current bus mode; and setting a direct current bus voltage reference value, rapidly reducing the tracking error of the direct current bus voltage based on an LQ optimal tracking control method, and realizing rapid and stable control of the direct current bus voltage. According to the method, the power difference between the photovoltaic power generation and the electrical load can be automatically compensated quickly and accurately, the direct-current bus voltage is ensured to be accurately stabilized at a set value all the time, and the comprehensive dynamic performance is better in the adjusting process.

Description

Technical Field

[0001] The present invention relates to the technical field of voltage stabilization control of photovoltaic power generation systems, and in particular to a voltage regulation method and system for a distributed photovoltaic storage system. Background Art

[0002] Photovoltaic power generation is an important means of utilizing solar energy resources. Since solar energy has natural resource infinity and cleanliness, the widespread application of photovoltaic power generation can effectively reduce environmental pollution caused by fossil energy consumption. However, in actual applications, lighting conditions are strongly related to factors such as season and weather. The radiation intensity that photovoltaic modules can absorb fluctuates greatly, resulting in its output power showing characteristics such as undispatchability and random volatility. In the scenario where distributed photovoltaic power generation systems are connected to the distribution network and operated in parallel, both photovoltaic power generation power and local load demand are random and it is impossible for the two to match completely. The resulting power difference needs to be compensated by the distribution network. Therefore, the fluctuation of photovoltaic power generation output power is bound to cause frequent disturbances to the distribution network, which is likely to cause low-frequency oscillations and affect the safe operation of the distribution network.

[0003] The energy storage system has the dual attributes of source and load. It can absorb the surplus power generated by the photovoltaic unit when the solar energy is concentrated, and can also perform rapid power compensation when the photovoltaic power output is insufficient. Configuring a battery energy storage system on the photovoltaic power generation side is not only conducive to improving the stability of the distribution network operation with photovoltaic access and increasing the distribution network's acceptance capacity for photovoltaics, but also helps to reduce resource waste and improve the utilization rate of solar energy. After the energy storage system is connected to the photovoltaic power generation system, an effective control method is needed to exert its rapid response capability and realize automatic and accurate compensation for power demand. At present, the control method of the energy storage system mainly uses a PI controller to achieve accurate tracking of the reference input, but the dynamic performance of the controlled system is usually difficult to achieve the optimal, and the dynamic response may have a large overshoot and a long adjustment time. Summary of the invention

[0004] In view of the problems existing in the voltage regulation and system of the existing distributed photovoltaic storage system, the present invention is proposed.

[0005] Therefore, the problem to be solved by the present invention is that the dynamic performance of the controlled system is usually difficult to achieve the optimum, and the dynamic response may have a large overshoot and a long adjustment time.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides a voltage regulation method for a distributed photovoltaic storage system, which comprises the following steps:

[0008] Obtain the irradiance intensity and ambient temperature data required for distributed photovoltaic storage system power generation;

[0009] Adjust the output voltage of the photovoltaic unit based on the disturbance control method to achieve maximum power point tracking control;

[0010] Obtain the load power demand and DC bus voltage data of the photovoltaic energy storage grid-connected system in the shared DC bus mode;

[0011] The DC bus voltage reference value is set, and the tracking error of the DC bus voltage is quickly reduced based on the LQ optimal tracking control method to achieve rapid and stable control of the DC bus voltage.

[0012] As a preferred solution of the voltage regulation method of the distributed photovoltaic storage system described in the present invention, the disturbance control method adjusts the terminal voltage of the photovoltaic unit by adjusting the step size and period, thereby changing the actual output power of the photovoltaic power generation subsystem and realizing the MPPT control of the photovoltaic unit. The state space model of the photovoltaic power generation subsystem is:

[0013]

[0014] Where U dc_ref is the DC bus voltage setting value on the output side of the Boost circuit, C1 is the filter capacitor on the DC / DC input side, L1 and R1 are the input inductor and equivalent resistance respectively, D1 is the control input of the switch tube, I pv is the output current of the photovoltaic unit, U pv is the output voltage of the photovoltaic unit, I sys1 This is the current injected into the DC bus by the PV subsystem.

[0015] As a preferred solution of the voltage regulation method of the distributed photovoltaic storage system described in the present invention, the relationship between the output voltage of the photovoltaic unit and the DC bus voltage of the system in steady state is obtained through the state space model of the photovoltaic power generation subsystem, and is expressed as:

[0016] U pv =R1I pv +(1-D1)U dc_ref ;

[0017] When the DC bus voltage can be quickly and accurately stabilized at the set value U dc_ref When the duty cycle D1 is changed, the output voltage of the photovoltaic unit can be adjusted, thereby realizing control based on the disturbance control method.

[0018] As a preferred solution of the voltage regulation method of the distributed photovoltaic storage system of the present invention, the distributed photovoltaic storage system adopts a single-phase inverter as an AC / DC power conversion unit, and an LCL filter is connected after the inverter to improve the power quality of the grid-connected current output by the inverter. The two together constitute an inverter subsystem, and its state space model is expressed as follows:

[0019]

[0020] Where, L3 and R3 are the inductance and equivalent resistance of the LCL filter input side, L4 and R4 are the inductance and equivalent resistance of the LCL filter output side, C3 is the capacitance of the LCL filter, u c is the terminal voltage of capacitor C3, u inv 、i inv are the voltage and current at the inverter output side, i out is the output current of the LCL filter.

[0021] As a preferred solution of the voltage regulation method of the distributed photovoltaic storage system described in the present invention, in order to realize independent control of active power and reactive power of the single-phase inverter, the dq coordinate transformation is performed on it by using the virtual orthogonal component method to obtain a model in the dq coordinate system, which is specifically expressed as:

[0022]

[0023] Where, θ = ωt, ω is the fundamental angular frequency;

[0024] The state space model of the inverter subsystem is transformed into dq coordinates to obtain a new state space model of the inverter subsystem in the dq coordinate system, which is specifically expressed as:

[0025]

[0026] A new inverter subsystem state space model is introduced with feedforward solution to obtain the active power and reactive power of the single-phase inverter subsystem.

[0027] As a preferred solution of the voltage regulation method of the distributed photovoltaic storage system described in the present invention, wherein: a bidirectional DC / DC is used as a control execution unit, and the fast charge / discharge characteristics of the battery are fully utilized to achieve stable control of the DC bus voltage. Its equivalent circuit model is composed of a DC voltage source E es and the equivalent series resistance R es It represents the energy storage subsystem, and its corresponding state space model is:

[0028]

[0029] In the formula, I es is the charge / discharge current of the energy storage unit, U es is the terminal voltage of the energy storage unit, L2 and R2 are the input inductance and equivalent resistance respectively, C dc is the DC bus capacitance, U dc is the DC bus voltage, I pl It is the current provided by the energy storage subsystem to the outside, and D2 is the switch tube control input.

[0030] As a preferred solution of the voltage regulation method of the distributed photovoltaic storage system described in the present invention, the energy storage subsystem sets the DC bus voltage to be stable at a set value U dc_ref .

[0031] In a second aspect, an embodiment of the present invention provides a distributed photovoltaic storage system voltage regulation system, which includes a maximum power point tracking control module, a photovoltaic unit output terminal voltage adjustment module, a DC bus voltage control module, and an LQ optimal tracking control module;

[0032] The maximum power point tracking control module continuously makes small disturbances to the voltage or current of the photovoltaic panel and observes the change of the photovoltaic output power, thereby adjusting the working point to achieve the maximum power output;

[0033] The photovoltaic unit output terminal voltage adjustment module is responsible for adjusting the photovoltaic unit output terminal voltage to achieve maximum power point tracking control;

[0034] The DC bus voltage control module is responsible for setting reference values ​​of the DC bus voltage and adjusting the system according to these values ​​to maintain voltage stability;

[0035] The LQ optimal tracking control module is based on the LQ optimal control theory and is used to quickly reduce the tracking error of the DC bus voltage and achieve rapid and stable control of the DC bus voltage.

[0036] In a third aspect, an embodiment of the present invention provides a computer device, including a memory and a processor, wherein the memory stores a computer program, wherein: when the processor executes the computer program, any step of the above-mentioned distributed photovoltaic storage system voltage regulation method is implemented.

[0037] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, any step of the above-mentioned distributed photovoltaic storage system voltage regulation method is implemented.

[0038] The beneficial effects of the present invention are: it can automatically compensate for the power difference between photovoltaic power generation and power load quickly and accurately, ensure that the DC bus voltage is always accurately stabilized at the set value, and the comprehensive dynamic performance during the adjustment process is better. Based on MPPT control, it can be ensured that the PV subsystem always operates at the maximum power point, and the dq control method is adopted for the single-phase inverter, which can realize independent control of active and reactive power, and has the ability to provide reactive support to the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0040] Figure 1 This is a structural diagram of a distributed photovoltaic storage system connected to a distribution network for a voltage regulation method of a distributed photovoltaic storage system.

[0041] Figure 2 This is a structural diagram of a distributed photovoltaic storage system connected to a distribution network with a common DC bus, which is a voltage regulation method for a distributed photovoltaic storage system.

[0042] Figure 3 Photovoltaic power generation subsystem topology diagram for the voltage regulation method of the distributed photovoltaic storage system.

[0043] Figure 4 The topology diagram of the inverter subsystem for the voltage regulation method of the distributed photovoltaic storage system.

[0044] Figure 5 The topology diagram of the battery energy storage subsystem for the voltage regulation method of the distributed photovoltaic storage system.

[0045] Figure 6 The performance of two controllers for voltage regulation methods in distributed photovoltaic storage systems is compared.

[0046] Figure 7 This is the dynamic response curve of the system when the PV irradiation intensity changes in the voltage regulation method of the distributed photovoltaic storage system. DETAILED DESCRIPTION

[0047] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0048] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0049] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0050] The present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0051] At the same time, in the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper, lower, inner and outer" are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first, second or third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0052] In the present invention, unless otherwise clearly specified and limited, the terms "install, connect, connect" should be understood in a broad sense, for example: it can be a fixed connection, a detachable connection or an integral connection; it can also be a mechanical connection, an electrical connection or a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] Example 1

[0054] Reference Figure 1 to Figure 5 , which is the first embodiment of the present invention, provides a voltage regulation method for a distributed photovoltaic storage system, comprising the following steps:

[0055] S1. Obtain the irradiance intensity and ambient temperature data required for the distributed photovoltaic storage system to generate electricity.

[0056] The distributed photovoltaic storage system adopts a single-phase inverter as an AC / DC power conversion unit. An LCL filter is connected after the inverter to improve the power quality of the grid-connected current output by the inverter. The two together constitute an inverter subsystem, and its state space model is expressed as:

[0057]

[0058] Where, L3 and R3 are the inductance and equivalent resistance of the LCL filter input side, L4 and R4 are the inductance and equivalent resistance of the LCL filter output side, C3 is the capacitance of the LCL filter, u c is the terminal voltage of capacitor C3, u inv 、i inv are the voltage and current at the inverter output side, i out is the output current of the LCL filter (according to the KCL principle, this value is the local load current i Load and grid current i grid sum).

[0059] In order to realize independent control of active power and reactive power of single-phase inverter, the virtual orthogonal component method is used to transform its dq coordinates and obtain the model in dq coordinate system, which is specifically expressed as:

[0060]

[0061] Where, θ = ωt, ω is the fundamental angular frequency;

[0062] The state space model of the inverter subsystem is transformed into dq coordinates to obtain a new state space model of the inverter subsystem in the dq coordinate system, which is specifically expressed as:

[0063]

[0064] A new inverter subsystem state space model is introduced with feedforward solution to obtain the active power and reactive power of the single-phase inverter subsystem.

[0065] S2. Adjust the output voltage of the photovoltaic unit based on the disturbance control method to achieve maximum power point tracking control.

[0066] The disturbance control method adjusts the terminal voltage of the photovoltaic unit by adjusting the step size and period, thereby changing the actual output power of the photovoltaic power generation subsystem and realizing the MPPT control of the photovoltaic unit. The state space model of the photovoltaic power generation subsystem is:

[0067]

[0068] Where U dc_ref is the DC bus voltage setting value on the output side of the Boost circuit, C1 is the filter capacitor on the DC / DC input side, L1 and R1 are the input inductor and equivalent resistance respectively, D1 is the control input of the switch tube, I pv is the output current of the photovoltaic unit, U pv is the output voltage of the photovoltaic unit, I sys1 This is the current injected into the DC bus by the PV subsystem.

[0069] The relationship between the output voltage of the photovoltaic unit and the DC bus voltage of the system in steady state is obtained through the state space model of the photovoltaic power generation system:

[0070] U pv =R1I pv +(1-D1)U dc_ref ;

[0071] When the DC bus voltage can be quickly and accurately stabilized at the set value U dc_ref When the duty cycle D1 is changed, the output voltage of the photovoltaic unit can be adjusted, thereby realizing control based on the disturbance control method.

[0072] S3. Obtain the load power demand and DC bus voltage data of the photovoltaic energy storage grid-connected system in the shared DC bus mode.

[0073] S4. Set the DC bus voltage reference value, and quickly reduce the tracking error of the DC bus voltage based on the LQ optimal tracking control method to achieve rapid and stable control of the DC bus voltage.

[0074] Distributed photovoltaic power generation system Figure 1 As shown, the PV module is connected to the distribution network in a bipolar connection form through a primary DC / DC chopper and a primary DC / AC inverter. The energy storage system is configured on the basis of the bipolar grid-connected structure. The topological connection structure is as follows Figure 2 The common DC bus method is shown to form an integrated photovoltaic and storage solution.

[0075] The distributed photovoltaic power generation and storage grid-connected system is divided into three subsystems from the perspective of control function, namely: Figure 3 The photovoltaic power generation subsystem composed of the photovoltaic unit and the unidirectional DC / DC shown in the figure, Figure 4 The inverter subsystem shown and Figure 5 The energy storage subsystem composed of the energy storage unit and the bidirectional DC / DC shown in the figure has an independent converter as a control execution unit.

[0076] The bidirectional DC / DC is used as the control execution unit, and the fast charge / discharge characteristics of the battery are fully utilized to achieve stable control of the DC bus voltage. Its equivalent circuit model consists of a DC voltage source E es and the equivalent series resistance R es It represents the energy storage subsystem, and its corresponding state space model is:

[0077]

[0078] In the formula, I es is the charge / discharge current of the energy storage unit, U es is the terminal voltage of the energy storage unit, L2 and R2 are the input inductance and equivalent resistance respectively, Cdc is the DC bus capacitance, U dc is the DC bus voltage, I pl It is the current provided by the energy storage subsystem to the outside, and D2 is the switch tube control input.

[0079] The energy storage subsystem sets the DC bus voltage to stabilize at a set value U dc_ref .

[0080] In summary, the power difference between photovoltaic power generation and power load can be automatically compensated quickly and accurately to ensure that the DC bus voltage is always accurately stabilized at the set value. The comprehensive dynamic performance during the adjustment process is better. Based on MPPT control, it can be ensured that the PV subsystem always operates at the maximum power point, and the dq control method is used for the single-phase inverter to achieve independent control of active and reactive power, and have the ability to provide reactive support to the distribution network.

[0081] Example 2

[0082] On the basis of the first embodiment, this embodiment further provides a distributed photovoltaic storage system voltage regulation system, including a maximum power point tracking control module, a photovoltaic unit output voltage adjustment module, a DC bus voltage control module, and an LQ optimal tracking control module;

[0083] The maximum power point tracking control module continuously makes small disturbances to the voltage or current of the photovoltaic panel and observes the change of the photovoltaic output power, thereby adjusting the working point to achieve the maximum power output;

[0084] The photovoltaic unit output terminal voltage adjustment module is responsible for adjusting the photovoltaic unit output terminal voltage to achieve maximum power point tracking control;

[0085] The DC bus voltage control module is responsible for setting reference values ​​of the DC bus voltage and adjusting the system according to these values ​​to maintain voltage stability;

[0086] The LQ optimal tracking control module is based on the LQ optimal control theory and is used to quickly reduce the tracking error of the DC bus voltage and achieve rapid and stable control of the DC bus voltage.

[0087] This embodiment also provides a computer device, which is suitable for the case of a distributed photovoltaic storage system voltage regulation method, including a memory and a processor; the memory is used to store computer executable instructions, and the processor is used to execute computer executable instructions to implement the distributed photovoltaic storage system voltage regulation method proposed in the above embodiment.

[0088] The computer device may be a terminal, and the computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a key, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse, etc.

[0089] This embodiment further provides a storage medium on which a computer program is stored. When the program is executed by a processor, the voltage regulation method for a distributed photovoltaic storage system proposed in the above embodiment is implemented.

[0090] The storage medium proposed in this embodiment and the data storage method proposed in the above embodiment belong to the same inventive concept. The technical details not fully described in this embodiment can be found in the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0091] Example 3

[0092] Reference Figure 6 and Figure 7 Based on the previous two embodiments, this embodiment provides a voltage regulation method for a distributed photovoltaic storage system. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0093] Based on the parameters shown in Table 1, a photovoltaic energy storage grid-connected system model is constructed. In the model, the photovoltaic unit consists of 5 components connected in series to form a string, and then 20 strings are connected in parallel. Its ideal maximum power is 18kW. In the Matlab / Simulink environment, with a step size of 1e-6s, the controller designed based on LQ optimal tracking control and the PI controller are used to simulate and compare the control effects of the DC bus voltage stability and automatic power compensation of the energy storage system, verifying the DC bus voltage stability control effect based on LQ optimal tracking control. The simulation results are shown in Figure 1. Figure 6 As shown, it can be seen that the dynamic adjustment process of the control method of the present invention is shorter, the dynamic response of the PI controller has a larger overshoot, which makes the adjustment time longer, and the comprehensive dynamic performance of the controller based on LQ optimal tracking control is better.

[0094] Table 1: PV and inverter subsystem configuration parameters

[0095]

[0096] In addition, the PV irradiation intensity changes from 800W / m2 to 1000W / m2 to 800W / m2 to 600W / m2 to 800W / m2 to 1000W / m2, and the control effect of the photovoltaic storage grid-connected system is verified when 7.5kW of reactive power is provided in 2s. The simulation results are shown in Figure 2. Figure 7 As shown, it can be seen that the method of the present invention ensures that the PV subsystem always operates at the maximum power point based on MPPT control, and adopts the dq control method to achieve independent control of active and reactive power. At the same time, automatic power compensation is achieved based on the battery energy storage system to ensure the stability of the DC bus voltage.

[0097] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A voltage regulation method for a distributed photovoltaic storage system, characterized in that: The following steps are included: Obtain the irradiance intensity and ambient temperature data required for distributed photovoltaic storage system power generation; Adjust the output voltage of the photovoltaic unit based on the disturbance control method to achieve maximum power point tracking control; Obtain the load power demand and DC bus voltage data of the photovoltaic energy storage grid-connected system in the shared DC bus mode; The DC bus voltage reference value is set, and the tracking error of the DC bus voltage is quickly reduced based on the LQ optimal tracking control method to achieve rapid and stable control of the DC bus voltage.

2. The voltage regulation method of a distributed photovoltaic storage system according to claim 1, characterized in that: The disturbance control method adjusts the terminal voltage of the photovoltaic unit by adjusting the step size and period, thereby changing the actual output power of the photovoltaic power generation subsystem and realizing the MPPT control of the photovoltaic unit. The state space model of the photovoltaic power generation subsystem is: Where U dc_ref is the DC bus voltage setting value on the output side of the Boost circuit, C1 is the filter capacitor on the DC / DC input side, L1 and R1 are the input inductor and equivalent resistance respectively, D1 is the control input of the switch tube, I pv is the output current of the photovoltaic unit, U pv is the output voltage of the photovoltaic unit, I sys1 This is the current injected into the DC bus by the PV subsystem.

3. The voltage regulation method of the distributed photovoltaic storage system according to claim 2, characterized in that: The relationship between the output voltage of the photovoltaic unit and the DC bus voltage of the system in steady state is obtained through the state space model of the photovoltaic power generation system: IN pv =R1I pv +(1-D1)U dc_re ; When the DC bus voltage can be quickly and accurately stabilized at the set value U dc_ref When the duty cycle D1 is changed, the output voltage of the photovoltaic unit can be adjusted, thereby realizing control based on the disturbance control method.

4. The voltage regulation method of a distributed photovoltaic storage system according to claim 3, characterized in that: The distributed photovoltaic storage system adopts a single-phase inverter as an AC / DC power conversion unit. An LCL filter is connected after the inverter to improve the power quality of the grid-connected current output by the inverter. The two together constitute an inverter subsystem, and its state space model is expressed as: Where, L3 and R3 are the inductance and equivalent resistance of the LCL filter input side, L4 and R4 are the inductance and equivalent resistance of the LCL filter output side, C3 is the capacitance of the LCL filter, u c is the terminal voltage of capacitor C3, u inv 、i inv are the voltage and current at the inverter output side, i out is the output current of the LCL filter.

5. The voltage regulation method of the distributed photovoltaic storage system according to claim 4, characterized in that: In order to realize independent control of active power and reactive power of single-phase inverter, the virtual orthogonal component method is used to transform its dq coordinates and obtain the model in dq coordinate system, which is specifically expressed as: Where, θ = ωt, ω is the fundamental angular frequency; The state space model of the inverter subsystem is transformed into dq coordinates to obtain a new state space model of the inverter subsystem in the dq coordinate system, which is specifically expressed as: A new inverter subsystem state space model is introduced with feedforward solution to obtain the active power and reactive power of the single-phase inverter subsystem.

6. The voltage regulation method of a distributed photovoltaic storage system according to claim 5, characterized in that: The bidirectional DC / DC is used as the control execution unit, and the fast charge / discharge characteristics of the battery are fully utilized to achieve stable control of the DC bus voltage. Its equivalent circuit model consists of a DC voltage source E es and the equivalent series resistance R es It represents the energy storage subsystem, and its corresponding state space model is: In the formula, I es is the charge / discharge current of the energy storage unit, U es is the terminal voltage of the energy storage unit, L2 and R2 are the input inductance and equivalent resistance respectively, C dc is the DC bus capacitance, U dc is the DC bus voltage, I pl It is the current provided by the energy storage subsystem to the outside, and D2 is the switch tube control input.

7. The voltage regulation method of a distributed photovoltaic storage system according to claim 6, characterized in that: The energy storage subsystem sets the DC bus voltage to stabilize at a set value U dc_ref .

8. A distributed photovoltaic storage system voltage regulation system, based on the distributed photovoltaic storage system voltage regulation method according to any one of claims 1 to 7, characterized in that: It includes a maximum power point tracking control module, a photovoltaic unit output voltage adjustment module, a DC bus voltage control module, and an LQ optimal tracking control module; The maximum power point tracking control module continuously makes small disturbances to the voltage or current of the photovoltaic panel and observes the change of the photovoltaic output power, thereby adjusting the working point to achieve the maximum power output; The photovoltaic unit output terminal voltage adjustment module is responsible for adjusting the photovoltaic unit output terminal voltage to achieve maximum power point tracking control; The DC bus voltage control module is responsible for setting reference values ​​of the DC bus voltage and adjusting the system according to these values ​​to maintain voltage stability; The LQ optimal tracking control module is based on the LQ optimal control theory and is used to quickly reduce the tracking error of the DC bus voltage and achieve rapid and stable control of the DC bus voltage.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the voltage regulation method of the distributed photovoltaic storage system according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the voltage regulation method of a distributed photovoltaic storage system according to any one of claims 1 to 7 are implemented.

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