A self-provisioned photovoltaic-based energy storage collaborative network control method and related device

Abstract

The application provides a self-provision photovoltaic-based energy storage grid coordination control method and related device, the method comprises the following steps: evaluating the power information corresponding to the maximum power point of the photovoltaic array in the current operating state to estimate the maximum power of the photovoltaic array; making the photovoltaic reach the target self-provision rate through variable step voltage tracking control; obtaining the estimated self-provision rate according to the maximum power and the output power of the photovoltaic array, obtaining the self-provision rate error according to the estimated self-provision rate and the target self-provision rate, adjusting the voltage tracking convergence by using the self-provision rate error, and converging to the operating point corresponding to the self-provision rate until convergence; using the synchronous mechanism grid rotor inertia power ring to design a transient rotor inertia power control strategy, so that the photovoltaic array with the auxiliary self-provision droop regulation characteristic participates in grid coordination. The application can effectively avoid the reconstruction of the photovoltaic array with large scale, meanwhile, the flexible access of the energy storage is realized, and the power supply reliability of the remote rural power grid with high self-provision rate is improved.

Description

Technical Field

[0001] The present invention relates to the field of energy storage inverter control, and in particular to a self-backup photovoltaic-based energy storage collaborative grid control method and related devices. Background Art

[0002] Photovoltaic resources have the characteristics of flexible access, renewable energy, and environmental friendliness. Therefore, they are widely used at the end of the distribution network and in remote rural areas to achieve the rational use of local natural resources, reduce the load on the power grid, increase the electricity self-sufficiency rate in remote rural areas, and improve the power supply reliability in remote rural areas.

[0003] However, the widespread deployment of distributed photovoltaic resources in remote rural grids presents numerous challenges to fragile rural power grids. First, as a renewable resource relying on solar power, photovoltaic power generation exhibits distinct time-of-day characteristics, often leading to high power generation during midday when rural grid load is low, while insufficient power is provided to support the grid during peak evening loads. This results in widespread curtailment and the risk of voltage exceeding limits, hindering the effective utilization of photovoltaic resources. Second, photovoltaic power generation is highly susceptible to natural factors, exhibiting significant volatility and uncertainty, leading to frequent fluctuations in power flow along rural grid lines. Furthermore, photovoltaic power generation relies on grid-connected power electronic devices, which respond quickly but lack inertia and networking capabilities. This, in turn, weakens the rural distribution network's ability to cope with power shortages and frequency fluctuations, further increasing risks to the safe operation of rural power grids. Consequently, virtual synchronous control technology with photovoltaic and energy storage, similar to the characteristics of a synchronous mechanism network, has been widely researched.

[0004] The control algorithm for grid-connected inverters for photovoltaic arrays is relatively easy to implement. However, the difficulty in implementing virtual synchronous control of photovoltaic and energy storage lies in the need to adjust and modify the grid-connected structure of the photovoltaic array, and the need to comprehensively design the coordination between photovoltaic and energy storage. This makes the design of the coordinated control algorithm complex and more difficult than simply changing the photovoltaic control algorithm. In reality, for the large number of photovoltaic resources already in operation in remote rural grid areas, large-scale photovoltaic grid-connected structure modification undoubtedly increases the cost investment and wastes the flexible characteristics of photovoltaic and energy storage grid connection. Therefore, it is important to retain the existing large number of photovoltaic array grid-connected structures in rural grids while rationally utilizing the auxiliary grid-connected characteristics of energy storage to improve the power supply reliability in remote rural grid areas.

[0005] The present invention designs a method for controlling energy storage-assisted grid construction based on self-backup photovoltaics. By modifying the traditional photovoltaic power control scheme, the self-backup of photovoltaic capacity is achieved. At the same time, a control strategy for energy storage-assisted grid construction is designed to achieve flexible access to energy storage and give full play to the auxiliary grid construction capability of energy storage. This effectively avoids the modification of existing photovoltaic grid-connected structures in remote areas, improves the photovoltaic resource grid construction capability in remote areas, and enhances power supply reliability. Summary of the Invention

[0006] In order to improve the networking capability of photovoltaic grid-connected resources in existing rural power grids in remote areas, reduce the cost of grid-connected equipment modification, and improve the power supply reliability of remote distribution networks, the present invention provides a storage-based collaborative grid control method and related devices based on self-backup photovoltaics, which fully utilize the flexible grid-connected characteristics of energy storage to coordinate photovoltaic grid construction, thereby improving the power supply reliability in remote areas without changing the existing photovoltaic grid-connected structure.

[0007] In a first aspect, the present invention provides a method for controlling energy storage collaborative grid construction based on self-backup photovoltaics, comprising the following steps:

[0008] Step 1: Evaluate the power information corresponding to the maximum power point of the photovoltaic array under the current operating conditions to estimate the maximum power of the photovoltaic array;

[0009] Step 2: Use variable-step voltage tracking control to achieve the target self-reserve rate of photovoltaic power generation: The estimated self-reserve rate is obtained based on the maximum power and output power of the photovoltaic array estimated in step 1. The self-reserve rate error is obtained based on the estimated self-reserve rate and the target self-reserve rate. The self-reserve rate error is used to adjust the voltage tracking convergence until it converges to the operating point corresponding to the self-reserve rate, reserving some power for operation to provide droop capability for the photovoltaic grid.

[0010] Step 3: Using the rotor inertia power loop based on the synchronous mechanism network, a transient rotor inertia power control strategy is designed to enable the photovoltaic array with auxiliary self-backup droop adjustment characteristics to participate in the grid.

[0011] Furthermore, step 1 specifically includes: using an improved variable step-size small perturbation observation scheme to track the maximum power of the photovoltaic operation state, and the disturbance voltage signal compensation adjustment amount in the improved variable step-size small perturbation observation scheme is expressed as:

[0012]

[0013] Where, , represents the variable step size adjustment coefficient; represents the photovoltaic array at time t

[0014] Output power; Represents the voltage perturbation step length at time t.

[0015] Furthermore, in step 1, the maximum power of the photovoltaic array is estimated, wherein

[0016] The estimated value Pres of the maximum power of the photovoltaic array is equivalently expressed as:

[0017]

[0018] Among them, kfit is the fitting coefficient, is the short-circuit current, I fit is the output current at the standby operation point, , , , , , ; r fit Indicates the self-reserve rate of the PV array.

[0019] Furthermore, the fitting coefficient k fit The relationship with temperature T is:

[0020]

[0021] in , .

[0022] Furthermore, the variable step size voltage tracking control in step 2 is designed as follows:

[0023]

[0024]

[0025] Where, represents the voltage reference value of the volt controller at time t, represents the voltage perturbation step at time t, Adjust the step size for the selected voltage; This means that the operating point is to the right of the maximum power point of the PV array. The voltage tracking control will gradually reduce the voltage output value of the PV array to return the operating point to the left of the maximum power point. This means that the PV array is operating on the left side of the maximum power point, and the voltage tracking control will automatically determine the voltage adjustment amount based on the value of the self-reserve rate deviation. The size and direction of the system are adjusted until it converges to the operating point corresponding to the self-reserve rate.

[0026] Furthermore, step three specifically includes:

[0027] According to the change of rotor speed caused by unbalanced power of synchronous machine, the rotor motion equation of synchronous machine is established:

[0028]

[0029] Where, J is the synchronous machine rotor moment of inertia, is the rotor angular velocity; 、 、 denote the input power, electric power and damping power of the synchronous machine respectively, where , D is the equivalent damping coefficient of the synchronous machine, is the rated angular velocity of the rotor;

[0030] The synchronous machine adjusts the input power through the regulating valve, and the droop regulation equation is expressed as:

[0031]

[0032] Where, is the rated power of the load, k is the droop coefficient of the control valve;

[0033] Model the inverter end and realize the synchronous machine characteristics. The inverter port outputs electrical power. Expressed as:

[0034]

[0035] Where, 、 Respectively represent the no-load voltage and actual port voltage output by the inverter, is the inverter filter impedance, ,in 、 Represent the filter inductance and filter resistance respectively, represents the filter impedance angle, , is the output power angle;

[0036] In filter circuits, reactance , so the filter impedance , filter impedance angle At the same time, due to the output power angle Very small, according to the trigonometric limit theorem, the electric power It can be expressed approximately as:

[0037]

[0038] In the synchronous machine's rotor motion equation, , output electrical power Rated power of load The transfer function between is expressed as:

[0039]

[0040] The relationship between the system angular frequency and power change is expressed as:

[0041]

[0042] Unifying the rotor damping power into the speed control equation, the input power is redefined as:

[0043]

[0044] Therefore, the input power Rated power of load The transfer function between is expressed as:

[0045]

[0046] In the process of simulating synchronous machines, the input power of the regulating valve shows a typical droop characteristic when responding to load changes, while the output characteristic shows a typical second-order response characteristic. The rotor of the synchronous machine stores and releases kinetic energy during the transient regulation process. The inertia power of the rotor during the transient regulation process is defined as , expressed as:

[0047]

[0048] Its load rated power The step response of the change is expressed as:

[0049]

[0050] Where, is the change in rated power of the load.

[0051] A self-support photovoltaic energy storage collaborative grid control device, comprising:

[0052] The maximum power estimation module is used to evaluate the power information corresponding to the maximum power point under the current operating conditions of the photovoltaic array to estimate the maximum power of the photovoltaic array;

[0053] The maximum power point tracking module is used to achieve the target self-reserve rate of photovoltaic power generation through variable-step voltage tracking control: the target estimated self-reserve rate is obtained based on the estimated maximum power and output power of the photovoltaic array. The self-reserve rate error is obtained based on the target estimated self-reserve rate and the target self-reserve rate. The self-reserve rate error is used to adjust the voltage tracking convergence until it converges to the operating point corresponding to the target self-reserve rate, reserving some power for operation to provide droop capability for photovoltaic grid construction;

[0054] The inertia power control module is used to design a transient rotor inertia power control strategy based on the synchronous mechanism network rotor inertia power loop, so that the photovoltaic array with auxiliary self-backup droop regulation characteristics can participate in the grid.

[0055] Furthermore, the inertia power control module is specifically used to:

[0056] According to the change of rotor speed caused by unbalanced power of synchronous machine, the rotor motion equation of synchronous machine is established:

[0057]

[0058] Where, J is the synchronous machine rotor moment of inertia, is the rotor angular velocity; 、 、 denote the input power, electric power and damping power of the synchronous machine respectively, where , D is the equivalent damping coefficient of the synchronous machine, is the rated angular velocity of the rotor;

[0059] The synchronous machine adjusts the input power through the regulating valve, and the droop regulation equation is expressed as:

[0060]

[0061] Where, is the rated power of the load, k is the droop coefficient of the control valve;

[0062] Model the inverter end and realize the synchronous machine characteristics. The inverter port outputs electrical power. Expressed as:

[0063]

[0064] Where, 、 Respectively represent the no-load voltage and actual port voltage output by the inverter, is the inverter filter impedance, ,in 、 Represent the filter inductance and filter resistance respectively, represents the filter impedance angle, , is the output power angle;

[0065] In filter circuits, reactance , so the filter impedance , filter impedance angle At the same time, due to the output power angle Very small, according to the trigonometric limit theorem, the electric power It can be expressed approximately as:

[0066]

[0067] In the synchronous machine's rotor motion equation, , output electrical power Rated power of load The transfer function between is expressed as:

[0068]

[0069] The relationship between the system angular frequency and power change is expressed as:

[0070]

[0071] Unifying the rotor damping power into the speed control equation, the input power is redefined as:

[0072]

[0073] Therefore, the input power Rated power of load The transfer function between is expressed as:

[0074]

[0075] In the process of simulating synchronous machines, the input power of the regulating valve shows a typical droop characteristic when responding to load changes, while the output characteristic shows a typical second-order response characteristic. The rotor of the synchronous machine stores and releases kinetic energy during the transient regulation process. The inertia power of the rotor during the transient regulation process is defined as , expressed as:

[0076]

[0077] Its load rated power The step response of the change is expressed as:

[0078]

[0079] Where, is the change in rated power of the load.

[0080] A self-backup photovoltaic-based energy storage collaborative grid control system, comprising: a computer-readable storage medium and a processor;

[0081] The computer-readable storage medium is used to store executable instructions;

[0082] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the self-backup photovoltaic-based energy storage collaborative grid control method.

[0083] A non-transitory computer-readable storage medium stores a computer program, which, when executed by a processor, implements the energy storage collaborative grid control method based on self-backup photovoltaics.

[0084] Compared with the existing methods, the present invention has the following advantages:

[0085] The proposed method leverages the flexible grid-connection capabilities of energy storage and offers plug-and-play functionality. In remote rural areas with existing large-scale photovoltaic grid-connected systems, variable-step voltage tracking control eliminates self-reserve rate errors, thereby improving maximum power estimation accuracy and ensuring photovoltaic absorption to a certain extent. This simplifies improvements to photovoltaic control strategies while avoiding large-scale modifications to the photovoltaic and energy storage access system topologies, significantly reducing renovation costs in rural areas. In terms of collaborative grid construction, a transient rotor inertia power control strategy is designed based on the synchronous machine network rotor inertia power loop, achieving grid construction similar to that of synchronous machines and improving power supply reliability in weak grids with a high photovoltaic ratio. This flexible configuration makes the proposed method more readily applicable than existing methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Figure 1 This is an improved variable step-size disturbance observation signal adjustment flow chart according to an embodiment of the present invention.

[0087] Figure 2 1 is a schematic diagram of a typical PU and IU curve of a photovoltaic array and its self-backup power point adjustment according to an embodiment of the present invention.

[0088] Figure 3 This is a voltage control flow chart for realizing self-backup of a photovoltaic array according to an embodiment of the present invention.

[0089] Figure 4 Schematic diagram of the output power composition of the synchronous machine according to an embodiment of the present invention.

[0090] Figure 5 This is a flow chart for implementing rotor inertia control according to an embodiment of the present invention.

[0091] Figure 6 This is a topological diagram of an energy storage-coordinated self-backup photovoltaic access system implemented in an embodiment of the present invention.

[0092] Figure 7 This is a control effect diagram (frequency effect and power effect) of an embodiment of the present invention. DETAILED DESCRIPTION

[0093] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0094] A first aspect of the present invention provides a method for controlling energy storage collaborative grid construction based on self-backup photovoltaics, comprising the following steps:

[0095] Step 1: Estimate the maximum power of the PV array.

[0096] The design of the photovoltaic self-backup control strategy depends on the power at the maximum power point of the photovoltaic under the current operating conditions. At present, the photovoltaic maximum power tracking (MPPT) control often uses the small disturbance observation method for tracking. Its accuracy depends on the disturbance step size. If the step size is too large, the tracking accuracy is insufficient; if the disturbance is too small, the tracking speed is too slow. Due to the fixed disturbance step size, the general disturbance observation method is difficult to balance the tracking accuracy and speed. Not only is it difficult to select a suitable tracking step size, but there are also problems such as easy misjudgment and output power oscillation at the maximum power point. In the embodiment of the present invention, a variable step size disturbance is designed to realize MPPT control. As a preferred embodiment, the step size adjustment amount of the disturbance voltage signal can be described as:

[0097]

[0098] Where, , represents the variable step size adjustment coefficient, and preferably, in the embodiment of the present invention, it is set to 2; Represents the output power of the photovoltaic array at time t

[0099] Rate; represents the voltage disturbance step at time t.

[0100] The specific disturbance signal adjustment process is as follows: Figure 1 As shown, Figure 1 Middle U t and I t They represent the output voltage and output current of the photovoltaic at time t respectively.

[0101] According to existing research, the maximum output power of photovoltaic and short-circuit current The relationship between them is approximately linear under the condition of changing illumination, so the approximate linear fitting expression can be expressed as:

[0102]

[0103] Where k fit is the fitting coefficient, which is related to the ambient temperature.

[0104] The fitting coefficient also shows a linear relationship with the ambient temperature. Under different ambient temperature conditions, the fitting coefficient k can be constructed fit The relationship with temperature T is:

[0105]

[0106] As a preferred method, the linear regression between the fitting coefficient and temperature can be obtained: , .

[0107] Figure 2 This is a typical PU and IU curve for a photovoltaic array. The essence of photovoltaic self-backup is to lower the power operating point along the output curve and reserve some power for operation. Figure 2 It can be seen that in order to avoid power fluctuations caused by drastic changes in current, the voltage should be lowered to shift the operating point to the left to find the photovoltaic self-backup power operating point. The output current I fit With short-circuit current I sc The relationship can be expressed by linear fitting as:

[0108]

[0109] As an optimization, the values ​​of the fitting coefficients are , , , , , ; r fit Indicates the self-reserve rate of the PV array.

[0110] Therefore, the estimated value of the maximum power of the photovoltaic array is P res It can be equivalently expressed as:

[0111]

[0112] Step 2: Use variable step size voltage tracking control to make the photovoltaic power reach the target self-reserve rate.

[0113] The specific process of self-backup voltage control can be Figure 3 Equivalent description. First, the photovoltaic power reaches the target self-reserve rate through variable step voltage tracking control. , according to the estimated maximum power value P of the photovoltaic array at the current time t t res With output power P t pv , estimated self-reserve rate at time t Expressed as:

[0114]

[0115] Generally speaking, the estimated self-reserve rate Self-responsibility ratio with target There is a certain error, the self-reserve rate error at time t Expressed as:

[0116]

[0117] Using the self-reserve rate error at time t Adjust the voltage tracking convergence to improve the accuracy of maximum power estimation. The variable step size voltage tracking control can be designed as follows:

[0118]

[0119]

[0120] Where, Indicates the voltage reference value of the photovoltaic controller at time t, Adjust the step size for the selected voltage; This means that the operating point is to the right of the maximum power point of the PV array. The voltage tracking control will gradually reduce the voltage output value of the PV array to return the operating point to the left of the maximum power point. This means that the PV array is operating on the left side of the maximum power point, and the voltage tracking control will automatically determine the voltage adjustment amount based on the value of the self-reserve rate deviation. The size and direction of the system are adjusted until it converges to the operating point corresponding to the self-reserve rate.

[0121] The photovoltaic self-backup algorithm provides the PV array with primary frequency regulation capabilities to meet droop control requirements. Through self-backup control, the PV array can adaptively adjust its output to meet the basic needs of the rural grid, effectively reducing curtailment and, to a certain extent, ensuring the rational consumption of PV resources. However, relying solely on the droop regulation capability of self-backup PV cannot provide sufficient grid inertia support. Therefore, in step 3, energy storage is added to provide effective inertia support.

[0122] Step 3: Using the synchronous mechanism network-based rotor inertia power loop, design a transient rotor inertia power control strategy. Specifically, decompose the output power into the speed control valve power and the transient rotor power. This allows the transient rotor power control scheme to be designed, enabling energy storage to coordinate with photovoltaic grid construction and maximize the system's grid construction capabilities.

[0123] To enhance the PV system's grid-building inertia support capabilities, the aforementioned steps provide the PV grid-building droop capability, and energy storage is added. For energy storage, the inverter control method needs to be improved to meet the characteristics of synchronous machines.

[0124] Step 3 specifically includes:

[0125] According to the change of rotor speed of synchronous machine caused by unbalanced power, the rotor motion equation of synchronous machine can be established as follows:

[0126]

[0127] Where, J is the synchronous machine rotor moment of inertia, is the rotor angular velocity; 、 、 denote the input power, electric power and damping power of the synchronous machine respectively, where , D is the equivalent damping coefficient of the synchronous machine, is the rated angular velocity of the rotor.

[0128] The synchronous machine adjusts the input power through the regulating valve, and the speed regulation equation (droop regulation equation) is expressed as:

[0129]

[0130] Where, is the rated power of the load, and k is the droop coefficient of the control valve.

[0131] Model the inverter end and realize the synchronous machine characteristics. The inverter port outputs electrical power. It can be expressed as:

[0132]

[0133] Where, 、 Respectively represent the no-load voltage and actual port voltage output by the inverter, is the inverter filter impedance, ,in 、 Represent the filter inductance and filter resistance respectively, represents the filter impedance angle, , is the output power angle.

[0134] In filter circuits, reactance , so the filter impedance , filter impedance angle At the same time, due to the output power angle Very small, according to the trigonometric limit theorem, the electric power It can be approximately expressed as:

[0135]

[0136] In the synchronous machine's rotor motion equation, Therefore, the output power Rated power of load The transfer function between is expressed as:

[0137]

[0138] The relationship between the system angular frequency and power change is expressed as:

[0139]

[0140] Unifying the rotor damping power into the speed control equation, the input power is redefined as:

[0141]

[0142] Therefore, the input power Rated power of load The transfer function between is expressed as:

[0143]

[0144] It can be seen that in the process of simulating synchronous machines, the input power of the regulating valve shows a typical droop characteristic when responding to load changes, while the output characteristic shows a typical second-order response characteristic. The rotor of the synchronous machine stores and releases kinetic energy during the transient regulation process, which improves the network construction capability. The power response characteristics of the three powers when responding to load disturbances are as follows: Figure 4 Therefore, the inertia power of the rotor during transient regulation is defined as , expressed as:

[0145]

[0146] Its load rated power The step response of the change can be expressed as:

[0147]

[0148] Where, is the change in rated power of the load.

[0149] Therefore, by designing Figure 5 The transient rotor inertia power control strategy shown in the figure can enable the photovoltaic array with auxiliary self-backup droop regulation characteristics to participate in the grid construction, and its external equivalent function is the synchronous machine characteristic. Its access structure and control effect are as follows: Figure 6 and Figure 7 shown.

[0150] This invention first designs a photovoltaic self-backup control scheme to improve photovoltaic maximum power tracking control, enabling photovoltaic power generation with grid-connected droop adjustment capabilities and achieving adaptive source-load matching. Furthermore, by analyzing the characteristics of the synchronous mechanism network, the rotor inertia power in transient characteristics is decomposed, and a corresponding control algorithm is designed and applied to energy storage control to coordinate photovoltaic grid connection and leverage the flexible access characteristics of energy storage. Finally, a simulation example verifies the external equivalent synchronous grid connection capability of self-backup photovoltaic power generation under energy storage coordination. This method effectively avoids the need for retrofitting existing large-scale photovoltaic systems while enabling flexible access to energy storage, improving the reliability of power supply to remote rural grids with high self-sufficiency rates.

[0151] Another aspect of the present invention provides a self-backup photovoltaic energy storage collaborative grid control device, comprising:

[0152] The maximum power estimation module is used to evaluate the power information corresponding to the maximum power point under the current operating conditions of the photovoltaic array to estimate the maximum power of the photovoltaic array;

[0153] The maximum power point tracking module is used to achieve the target self-reserve rate of photovoltaic power generation through variable-step voltage tracking control: the target estimated self-reserve rate is obtained based on the estimated maximum power and output power of the photovoltaic array. The self-reserve rate error is obtained based on the target estimated self-reserve rate and the target self-reserve rate. The self-reserve rate error is used to adjust the voltage tracking convergence until it converges to the operating point corresponding to the target self-reserve rate, reserving some power for operation to provide droop capability for photovoltaic grid construction;

[0154] The inertia power control module is used to design a transient rotor inertia power control strategy based on the synchronous mechanism network rotor inertia power loop, so that the photovoltaic array with auxiliary self-backup droop regulation characteristics can participate in the grid construction.

[0155] Another aspect of the present invention provides a self-backup photovoltaic-based energy storage collaborative grid control system, comprising: a computer-readable storage medium and a processor;

[0156] The computer-readable storage medium is used to store executable instructions;

[0157] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the self-backup photovoltaic-based energy storage collaborative grid control method described in the first aspect.

[0158] Another aspect of the present invention provides a non-transitory computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for controlling energy storage collaborative grid construction based on self-backup photovoltaics described in the first aspect is implemented.

[0159] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0160] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0161] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0162] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0163] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for controlling energy storage cooperative network construction based on self-backup photovoltaic, characterized in that: The steps include: Step 1: Evaluate the power information corresponding to the maximum power point of the photovoltaic array under the current operating conditions to estimate the maximum power of the photovoltaic array; Step 2: Use variable-step voltage tracking control to achieve the target self-reserve rate of photovoltaic power generation: The estimated self-reserve rate is obtained based on the maximum power and output power of the photovoltaic array estimated in step 1. The self-reserve rate error is obtained based on the estimated self-reserve rate and the target self-reserve rate. The self-reserve rate error is used to adjust the voltage tracking convergence until it converges to the operating point corresponding to the target self-reserve rate, reserving some power for operation to provide droop capability for the photovoltaic grid. Step 3: Using the rotor inertia power loop based on the synchronous mechanism network, a transient rotor inertia power control strategy is designed to enable the photovoltaic array with auxiliary self-backup droop adjustment characteristics to participate in the grid.

2. The method for controlling energy storage cooperative grid construction based on self-backup photovoltaic power generation according to claim 1, characterized in that: Step 1 specifically includes: using an improved variable step-size small perturbation observation scheme to track the maximum power of the photovoltaic operation state, and the disturbance voltage signal compensation adjustment amount in the improved variable step-size small perturbation observation scheme is expressed as: Where, Indicates the variable step size adjustment coefficient; Indicates the output power of the photovoltaic array at time t; ΔU t Represents the voltage perturbation step length at time t.

3. The method for controlling energy storage cooperative network construction based on self-backup photovoltaic power generation according to claim 2 is characterized in that: In step 1, the maximum power of the photovoltaic array is estimated, where the estimated value Pres of the maximum power of the photovoltaic array is equivalently expressed as: Among them, k fit is the fitting coefficient, I sc is the short-circuit current, I fit is the output current at the standby operation point, r fit Indicates the self-reserve rate of the PV array.

4. The method for controlling energy storage cooperative grid construction based on self-backup photovoltaic power generation according to claim 3, characterized in that: The fitting coefficient k fit The relationship with temperature T is: k fit =-λT-μ Among them, λ=0.898 and μ=-275.

4.

5. The method for controlling energy storage cooperative grid construction based on self-backup photovoltaic power generation according to claim 1, characterized in that: The variable step size voltage tracking control design in step 2 is: Where, Indicates the voltage reference value of the photovoltaic controller at time t, ΔU t Indicates the voltage disturbance step at time t, U Δ Adjust the step size for the selected voltage; If dP / dU < 0, it means that the operating point is on the right side of the maximum power point of the photovoltaic array. The voltage tracking control will gradually reduce the voltage output value of the photovoltaic array to make the operating point return to the left side of the maximum power point. If dP / dU ≥ 0, it means that the photovoltaic array is operating on the left side of the maximum power point. The voltage tracking control will automatically determine the voltage adjustment amount ΔU according to the value of the self-reserve rate deviation. t The size and direction of the system are adjusted until it converges to the operating point corresponding to the self-reserve rate.

6. The method for controlling energy storage cooperative network construction based on self-backup photovoltaic power generation according to claim 1, characterized in that: Step three specifically includes: According to the change of rotor speed caused by unbalanced power of synchronous machine, the rotor motion equation of synchronous machine is established: Where, J is the synchronous machine rotor moment of inertia, ω m is the rotor angular velocity; P m 、P e 、P D Represent the input power, electric power and damping power of the synchronous machine respectively, where P D =D(ω m -ω n ), D is the equivalent damping coefficient of the synchronous machine, ω n is the rated angular velocity of the rotor; The synchronous machine adjusts the input power through the regulating valve, and the droop regulation equation is expressed as: P m =P ref +k(ω n -oh m ) Where, P ref is the rated power of the load, k is the droop coefficient of the control valve; When the inverter side is modeled and the synchronous machine characteristics are realized, the inverter port output power P e Expressed as: Where, E0, U l They represent the no-load voltage and actual port voltage output by the inverter, respectively. f is the inverter filter impedance, Among them L f 、R f They represent filter inductance and filter resistance respectively, α represents filter impedance angle, α=arctan(ωL f / R f ), δ0 is the output power angle; In the filter circuit, the reactance X f =ωL f >>R f , so the filter impedance Z f ≈X f , the filter impedance angle α≈π / 2; at the same time, since the output power angle δ0 is very small, according to the limit theorem of trigonometric functions, the electric power P e It can be expressed approximately as: In the synchronous machine rotor motion equation, ω m ≈ω n , output power P e With load rated power P ref The transfer function between is expressed as: The relationship between the system angular frequency and power change is expressed as: Unifying the rotor damping power into the speed control equation, the input power is redefined as: P m =P ref +k(ω n -oh m )-Dω n (oh m -oh n ) Therefore, the input power P m and load rated power P ref The transfer function between is expressed as: In the process of simulating synchronous machines, the input power of the regulating valve shows a typical droop characteristic when responding to load changes, while the output characteristic shows a typical second-order response characteristic. The rotor of the synchronous machine stores and releases kinetic energy during the transient regulation process. The inertia power of the rotor during the transient regulation process is defined as P J , expressed as: The load rated power P ref The step response of the change is expressed as: Where ΔP ref is the change in rated power of the load.

7. A self-supporting photovoltaic energy storage collaborative grid control device, characterized by: include: The maximum power estimation module is used to evaluate the power information corresponding to the maximum power point under the current operating conditions of the photovoltaic array to estimate the maximum power of the photovoltaic array; The maximum power point tracking module is used to achieve the target self-reserve rate of photovoltaic power generation through variable-step voltage tracking control: the target estimated self-reserve rate is obtained based on the estimated maximum power and output power of the photovoltaic array. The self-reserve rate error is obtained based on the target estimated self-reserve rate and the target self-reserve rate. The self-reserve rate error is used to adjust the voltage tracking convergence until it converges to the operating point corresponding to the target self-reserve rate, reserving some power for operation to provide droop capability for photovoltaic grid construction; The inertia power control module is used to design a transient rotor inertia power control strategy based on the synchronous mechanism network rotor inertia power loop, so that the photovoltaic array with auxiliary self-backup droop regulation characteristics can participate in the grid.

8. The energy storage collaborative grid control device based on self-backup photovoltaics according to claim 7, characterized in that: The inertia power control module is specifically used to: According to the change of rotor speed caused by unbalanced power of synchronous machine, the rotor motion equation of synchronous machine is established: Where, J is the synchronous machine rotor moment of inertia, ω m is the rotor angular velocity; P m 、P e 、P D Represent the input power, electric power and damping power of the synchronous machine respectively, where P D =D(ω m -ω n ), D is the equivalent damping coefficient of the synchronous machine, ω n is the rated angular velocity of the rotor; The synchronous machine adjusts the input power through the regulating valve, and the droop regulation equation is expressed as: P m =P ref +k(ω n -oh m ) Where, P ref is the rated power of the load, k is the droop coefficient of the control valve; When the inverter side is modeled and the synchronous machine characteristics are realized, the inverter port output power P e Expressed as: Where, E0, U l They represent the no-load voltage and actual port voltage output by the inverter, respectively. f is the inverter filter impedance, Among them L f 、R f They represent filter inductance and filter resistance respectively, α represents filter impedance angle, α=arctan(ωL f / R f ), δ0 is the output power angle; In the filter circuit, the reactance X f =ωL f >>R f , so the filter impedance Z f ≈X f , the filter impedance angle α≈π / 2; at the same time, since the output power angle δ0 is very small, according to the limit theorem of trigonometric functions, the electric power P e It can be expressed approximately as: In the synchronous machine rotor motion equation, ω m ≈ω n , output power P e With load rated power P ref The transfer function between is expressed as: The relationship between the system angular frequency and power change is expressed as: Unifying the rotor damping power into the speed control equation, the input power is redefined as: P m =P ref +k(ω n -oh m )-Dω n (oh m -oh n ) Therefore, the input power P m and load rated power P ref The transfer function between is expressed as: In the process of simulating synchronous machines, the input power of the regulating valve shows a typical droop characteristic when responding to load changes, while the output characteristic shows a typical second-order response characteristic. The rotor of the synchronous machine stores and releases kinetic energy during the transient regulation process. The inertia power of the rotor during the transient regulation process is defined as P J , expressed as: The load rated power P ref The step response of the change is expressed as: Where ΔP ref is the change in rated power of the load.

9. A self-supporting photovoltaic energy storage collaborative grid control system, comprising: Computer-readable storage medium and processor; The computer-readable storage medium is used to store executable instructions; The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the self-backup photovoltaic-based energy storage collaborative grid control method according to any one of claims 1 to 6.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the method for controlling energy storage collaborative grid construction based on self-backup photovoltaic power generation according to any one of claims 1 to 6 is implemented.

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