Energy storage cooperative networking control method based on self-provided photovoltaic and related device

Abstract

The invention provides an energy storage cooperative networking control method based on self-provided photovoltaic and a related device. The method comprises the following steps: evaluating power information corresponding to a maximum power point of a photovoltaic array under a current operation condition so as to estimate the maximum power of the photovoltaic array; obtaining an estimated self-reserve rate according to the maximum power and the output power of the photovoltaic array, obtaining a self-reserve rate error according to the estimated self-reserve rate and the self-reserve rate of the target, and adjusting voltage tracking convergence by using the self-reserve rate error, the operation point corresponding to the self-reserve rate is converged; a transient rotor inertia power control strategy is designed by using a synchronous mechanism network-based rotor inertia power ring, so that a photovoltaic array with energy storage having an auxiliary self-standby droop adjustment characteristic participates in network construction. According to the invention, the transformation of applied large-scale photovoltaic can be effectively avoided, the flexible access of energy storage is realized, and the power supply reliability of the remote rural power grid with high self-sufficiency 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 networking control method and related devices. Background Art

[0002] At present, under the dual carbon background of "carbon peak and carbon neutrality", my country has made great efforts to develop renewable energy, which has become a national strategic priority and social consensus. Renewable energy represented by photovoltaic resources has been vigorously developed. At the same time, 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 self-sufficiency rate of electricity in remote rural areas, and improve the reliability of power supply in remote rural areas.

[0003] However, the large-scale commissioning of distributed photovoltaic resources in remote rural power grid scenarios has brought many severe challenges to the weak rural power grid. First, as a renewable resource that relies on solar energy for power generation, photovoltaic power generation has obvious time characteristics, which often leads to large photovoltaic power generation when the rural power grid load is small at noon, and cannot provide sufficient power support for the rural power grid during the peak load in the evening, which leads to a large number of abandoned light phenomena and the risk of voltage exceeding the limit of the rural power grid, and photovoltaic resources have not been reasonably utilized; secondly, photovoltaic power generation is very susceptible to natural conditions and factors, and there is obvious volatility and uncertainty, which leads to frequent fluctuations in the power flow of rural power grid lines; in addition, since photovoltaic power generation relies on power electronic devices to be connected to the grid, and power electronic devices respond quickly, lack inertia, and have insufficient network construction capabilities, the ability of rural distribution networks to cope with power shortages and frequency fluctuations is weakened to a certain extent, resulting in further increased risks of safe operation of rural power grids. Therefore, the photovoltaic storage virtual synchronous control technology with characteristics similar to the synchronous mechanism network has been widely studied.

[0004] The control algorithm of the photovoltaic array grid-connected inverter is relatively easy to implement. However, the difficulty in implementing the virtual synchronous control of photovoltaic and energy storage is that the photovoltaic array grid-connected structure needs to be adjusted and modified, and the coordination of photovoltaic and energy storage needs to be comprehensively designed, which makes the design of the coordinated control algorithm complex, which is more difficult than just changing the photovoltaic control algorithm. In actual situations, for the large number of photovoltaic resources that have been put into operation in remote rural power grids, the large-scale photovoltaic grid-connected structure transformation has undoubtedly increased the cost investment, and at the same time, it has also wasted the flexible characteristics of photovoltaic and energy storage grid connection. Therefore, it is of great significance to retain the existing large number of photovoltaic array grid-connected structures in the rural power grid, and at the same time reasonably utilize the auxiliary grid-connected characteristics of energy storage flexible grid connection to improve the power supply reliability in remote rural power grids.

[0005] The present invention designs a method for controlling energy storage collaborative networking based on self-backup photovoltaics. By transforming the traditional photovoltaic power control scheme, the self-backup of photovoltaic capacity is realized. At the same time, an energy storage collaborative networking control strategy is designed to realize flexible access to energy storage and give full play to the auxiliary networking capability of energy storage, effectively avoiding the transformation of existing photovoltaic grid-connected structures in remote areas, improving the photovoltaic resource networking capability in remote areas, and improving power supply reliability. Summary of the invention

[0006] In order to improve the networking capability of photovoltaic grid-connected resources put into operation in existing rural power grids in remote areas, reduce the cost of grid-connected equipment transformation, and improve the power supply reliability of remote distribution networks, the present invention provides a storage energy collaborative networking control method and related devices based on self-backup photovoltaics, which fully utilize the flexible grid-connected characteristics of energy storage to coordinate photovoltaic networking, and improve 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 cooperative network construction based on self-backup photovoltaic, 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 condition to estimate the maximum power of the photovoltaic array;

[0009] Step 2: Use variable step size voltage tracking control to make the photovoltaic reach the target self-reserve rate: obtain the estimated self-reserve rate based on the maximum power and output power of the photovoltaic array estimated in step 1, obtain the self-reserve rate error based on the estimated self-reserve rate and the target self-reserve rate, and use the self-reserve rate error to adjust the voltage tracking convergence until it converges to the operating point corresponding to the self-reserve rate, and reserve some power for operation to provide the photovoltaic grid droop capability;

[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 regulation characteristics to participate in the grid construction.

[0011] Further, step one specifically includes: using an improved variable step-size small disturbance 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 disturbance observation scheme is expressed as:

[0012]

[0013] In the formula, Represents the variable step size adjustment coefficient; Indicates the output power of the photovoltaic array at time t; ΔU t Represents the voltage disturbance step length at time t.

[0014] Furthermore, in step 1, the maximum power of the photovoltaic array is estimated, wherein the estimated value Pres of the maximum power of the photovoltaic array is equivalently expressed as:

[0015]

[0016] 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.

[0017] Furthermore, the fitting coefficient k fit The relationship with temperature T is:

[0018] k fit =-λT-μ

[0019] Among them, λ=0.898 and μ=-275.4.

[0020] Furthermore, the variable step size voltage tracking control in step 2 is designed as:

[0021]

[0022] In the formula, Indicates the voltage reference value of the volt controller at time t, ΔU t represents the voltage disturbance step at time t, U Δ is the selected voltage adjustment step; dP / dU<0 means that the operating point is on the right side of the maximum power point of the photovoltaic array, and the voltage tracking control will gradually reduce the voltage output value of the photovoltaic array to return the operating point to the left side of the maximum power point; dP / dU≥0 means that the photovoltaic array is operating on the left side of the maximum power point, and 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 change until it converges to the operating point corresponding to the self-reserve rate.

[0023] Furthermore, step three specifically includes:

[0024] According to the change of rotor speed of synchronous machine caused by unbalanced power, the rotor motion equation of synchronous machine is established:

[0025]

[0026] Where, J is the synchronous machine rotor moment of inertia, ω m is the rotor angular velocity; P m , P e , P DRespectively represent the input power, electric power and damping power of the synchronous machine, where P D =D(ω m -ω n ), D is the equivalent damping coefficient of the synchronous machine, ω n is the rated angular speed of the rotor;

[0027] The synchronous machine adjusts the input power through the regulating valve, and the droop regulation equation is expressed as:

[0028] P m =P ref +k(ω n -ω m )

[0029] Where P ref is the rated power of the load, k is the droop coefficient of the regulating valve;

[0030] When the inverter end is modeled and the synchronous machine characteristics are realized, the inverter port output power P e It is expressed as:

[0031]

[0032] In the formula, E 0 , U l They represent the no-load voltage and actual port voltage of the inverter output respectively, Z f is the inverter filter impedance, Where L f , R f They represent filter inductance and filter resistance respectively, α represents filter impedance angle, α=arctan(ωL f / R f ), δ 0 is the output power angle;

[0033] 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, due to the output power angle δ 0 Very small, according to the limit theorem of trigonometric functions, the electric power P e It can be expressed approximately as:

[0034]

[0035] 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:

[0036]

[0037] The relationship between the system angular frequency and power change is expressed as:

[0038]

[0039] The rotor damping power is unified into the speed control equation, and the input power is redefined as:

[0040] P m =P ref +k(ω n -ω m )-Dω n (ω m -ω n )

[0041] Therefore, the input power P m With load rated power P ref The transfer function between is expressed as:

[0042]

[0043] 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:

[0044]

[0045] Its load rated power P ref The step response of the change is expressed as:

[0046]

[0047] In the formula, ΔP ref is the change in rated power of the load.

[0048] A self-backup photovoltaic energy storage collaborative network control device, comprising:

[0049] The maximum power estimation module is used to evaluate the power information corresponding to the maximum power point of the photovoltaic array under the current operating condition to estimate the maximum power of the photovoltaic array;

[0050] The maximum power point tracking module is used to achieve the target self-reserve rate of photovoltaic power through variable step voltage tracking control: the estimated target self-reserve rate is obtained according to the estimated maximum power and output power of the photovoltaic array, the self-reserve rate error is obtained according to the target estimated self-reserve rate and the target self-reserve rate, and the voltage tracking convergence is adjusted by using the self-reserve rate error until it converges to the operating point corresponding to the target self-reserve rate, and some power is reserved for operation to provide the droop capability of photovoltaic grid construction;

[0051] The inertia power control module is used to design a transient rotor inertia power control strategy based on the rotor inertia power loop of the synchronous mechanism network, so that the photovoltaic array with auxiliary self-backup droop regulation characteristics can participate in the grid construction.

[0052] Furthermore, the inertia power control module is specifically used for:

[0053] According to the change of rotor speed of synchronous machine caused by unbalanced power, the rotor motion equation of synchronous machine is established:

[0054]

[0055] Where, J is the synchronous machine rotor moment of inertia, ω m is the rotor angular velocity; P m , P e , P D Respectively represent the input power, electric power and damping power of the synchronous machine, where P D =D(ω m -ω n ), D is the equivalent damping coefficient of the synchronous machine, ω n is the rated angular speed of the rotor;

[0056] The synchronous machine adjusts the input power through the regulating valve, and the droop regulation equation is expressed as:

[0057] P m =P ref +k(ω n -ω m )

[0058] Where P ref is the rated power of the load, k is the droop coefficient of the regulating valve;

[0059] When the inverter end is modeled and the synchronous machine characteristics are realized, the inverter port output power P e It is expressed as:

[0060]

[0061] In the formula, E 0 , U lThey represent the no-load voltage and actual port voltage of the inverter output respectively, Z f is the inverter filter impedance, Where L f , R f They represent filter inductance and filter resistance respectively, α represents filter impedance angle, α=arctan(ωL f / R f ), δ 0 is the output power angle;

[0062] 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, due to the output power angle δ 0 Very small, according to the limit theorem of trigonometric functions, the electric power P e It can be expressed approximately as:

[0063]

[0064] 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:

[0065]

[0066] The relationship between the system angular frequency and power change is expressed as:

[0067]

[0068] The rotor damping power is unified into the speed control equation, and the input power is redefined as:

[0069] P m =P ref +k(ω n -ω m )-Dω n (ω m -ω n )

[0070] Therefore, the input power P m With load rated power P ref The transfer function between is expressed as:

[0071]

[0072] 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:

[0073]

[0074] Its load rated power P ref The step response of the change is expressed as:

[0075]

[0076] Where ΔP ref is the change in rated power of the load.

[0077] A self-backup photovoltaic-based energy storage collaborative grid control system, comprising: a computer-readable storage medium and a processor;

[0078] The computer-readable storage medium is used to store executable instructions;

[0079] The processor is used to read the executable instructions stored in the computer-readable storage medium to execute the self-backup photovoltaic-based energy storage collaborative grid control method described in any one of claims 1-6.

[0080] A non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the energy storage collaborative grid control method based on self-backup photovoltaics as described in any one of claims 1-6.

[0081] Compared with the existing methods, the present invention has the following advantages:

[0082] The method proposed by the present invention can give full play to the flexible grid-connected characteristics of energy storage, and has plug-and-play characteristics. In the operation scenario of large-scale photovoltaic grid-connected rural power grids in remote areas, variable step-size voltage tracking control is used to eliminate the self-reserve rate error, thereby improving the maximum power estimation accuracy, ensuring photovoltaic absorption to a certain extent, simplifying the improvement of photovoltaic control strategy, and avoiding large-scale transformation of photovoltaic and energy storage access system topology, greatly reducing the transformation cost of rural power grid areas, and using the synchronous mechanism network rotor inertia power ring in collaborative networking, designing transient rotor inertia power control strategy, achieving a networking effect similar to the characteristics of synchronous machines, and improving the power supply reliability in high-proportion photovoltaic weak power grids. The flexible setting method makes the present invention easier to promote and apply than existing methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] Figure 1It is a flowchart of the improved variable step-size disturbance observation signal adjustment according to an embodiment of the present invention.

[0084] Figure 2 It is a schematic diagram of typical PU and IU curves of a photovoltaic array and its self-backup power point adjustment according to an embodiment of the present invention.

[0085] 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.

[0086] Figure 4 It is a schematic diagram of the output power composition of the synchronous machine according to an embodiment of the present invention.

[0087] Figure 5 It is a flow chart for implementing rotor inertia control according to an embodiment of the present invention.

[0088] Figure 6 It is a topological diagram of an energy storage-coordinated self-backup photovoltaic access system implemented in an embodiment of the present invention.

[0089] Figure 7 It is a control effect diagram (frequency effect and power effect) of an embodiment of the present invention. DETAILED DESCRIPTION

[0090] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the 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 creative work are within the scope of protection of the present invention.

[0091] The first aspect of the present invention provides a method for controlling energy storage cooperative network construction based on self-backup photovoltaic, comprising the following steps:

[0092] Step 1: Estimate the maximum power of the PV array.

[0093] 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:

[0094]

[0095] In the formula, 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

[0096] Rate; ΔU t represents the voltage disturbance step at time t.

[0097] 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.

[0098] According to existing research, the maximum photovoltaic output power P maxpv With short-circuit current I sc The relationship between them is approximately linear under the condition of changing illumination, so its approximate linear fitting expression can be expressed as:

[0099] P maxpv =k fit I sc

[0100] In the formula, k fit is the fitting coefficient, which is related to the ambient temperature.

[0101] 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:

[0102] k fit =-λT-μ

[0103] Preferably, through linear regression of the fitting coefficient and temperature, it can be obtained that λ=0.898 and μ=-275.4.

[0104] Figure 2 This is a typical PU and IU curve of a photovoltaic array. The essence of photovoltaic self-backup is to lower the power operation 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-reserve power operating point. The output current I fit With short-circuit current I sc The relationship can be expressed by linear fitting as:

[0105]

[0106] As a preference, the values ​​of the fitting coefficients are r fit Indicates the self-reserve rate of the PV array.

[0107] Therefore, the estimated value of the maximum power of the photovoltaic array is P res It can be equivalently expressed as:

[0108]

[0109] Step 2: Use variable step size voltage tracking control to make the photovoltaic power reach the target self-reserve rate.

[0110] The specific process of self-backup voltage control can be Figure 3 First, the photovoltaic power generation reaches the target self-reserve rate through variable step voltage tracking control. According to the estimated maximum power of the photovoltaic array at the current time t With output power Estimated self-reserve rate at time t It is expressed as:

[0111]

[0112] Generally speaking, the estimated reserve ratio Self-reserve ratio with target There is a certain error, the self-reserve rate error Δr at time t t It is expressed as:

[0113]

[0114] Using the self-reserve rate error Δr at time t 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:

[0115]

[0116] In the formula, Indicates the voltage reference value of the photovoltaic controller at time t, U Δ is the selected voltage adjustment step; dP / dU<0 means that the operating point is on the right side of the maximum power point of the photovoltaic array, and the voltage tracking control will gradually reduce the voltage output value of the photovoltaic array to return the operating point to the left side of the maximum power point; dP / dU≥0 means that the photovoltaic array is operating on the left side of the maximum power point, and 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 change until it converges to the operating point corresponding to the self-reserve rate.

[0117] The photovoltaic self-reserve algorithm provides the photovoltaic array with a primary frequency regulation capability to meet the droop control. Through the self-reserve control, the photovoltaic array can adaptively adjust the output to meet the basic needs of the rural grid, effectively reducing the phenomenon of abandoned light, and to a certain extent ensuring the reasonable consumption of photovoltaic resources. However, relying solely on the droop regulation capability of the self-reserve photovoltaic cannot provide sufficient inertia support for the network construction. Therefore, in step 3, effective inertia support is provided by adding energy storage synergy.

[0118] Step 3: Using the rotor inertia power loop based on the synchronous mechanism network, design a transient rotor inertia power control strategy. Specifically, the output power is decomposed into the speed control valve power and the transient rotor power, so as to design a transient rotor power control scheme to enable energy storage to cooperate with photovoltaic grid construction and maximize the system's grid construction capability.

[0119] In order to enhance the grid inertia support capability of the photovoltaic system, the energy storage link is further added on the basis of the photovoltaic grid droop capability provided in the above steps. For energy storage, the control method of its inverter needs to be improved to meet the characteristics of the synchronous machine.

[0120] Step 3 specifically includes:

[0121] 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:

[0122]

[0123] Where, J is the synchronous machine rotor moment of inertia, ω m is the rotor angular velocity; P m , P e , P D Respectively represent the input power, electric power and damping power of the synchronous machine, where P D =D(ω m -ω n ), D is the equivalent damping coefficient of the synchronous machine, ω n is the rated angular speed of the rotor.

[0124] The synchronous machine adjusts the input power through the regulating valve, and the speed regulation equation (droop regulation equation) is expressed as:

[0125] P m =P ref +k(ω n -ω m )

[0126] Where P ref is the rated power of the load, and k is the droop coefficient of the control valve.

[0127] When the inverter end is modeled and the synchronous machine characteristics are realized, the inverter port output power P eIt can be expressed as:

[0128]

[0129] In the formula, E 0 , U l They represent the no-load voltage and actual port voltage of the inverter output respectively, Z f is the inverter filter impedance, Where L f , R f They represent filter inductance and filter resistance respectively, α represents filter impedance angle, α=arctan(ωL f / R f ), δ 0 is the output power angle.

[0130] 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, due to the output power angle δ 0 Very small, according to the limit theorem of trigonometric functions, the electric power P e It can be approximately expressed as:

[0131]

[0132] In the synchronous machine rotor motion equation, ω m ≈ω n Therefore, the output power P e With load rated power P ref The transfer function between is expressed as:

[0133]

[0134] The relationship between the system angular frequency and power change is expressed as:

[0135]

[0136] The rotor damping power is unified into the speed control equation, and the input power is redefined as:

[0137] P m =P ref +k(ω n -ω m )-Dω n (ω m -ω n )

[0138] Therefore, the input power P m With load rated power P refThe transfer function between is expressed as:

[0139]

[0140] 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 transient regulation, which improves the network building 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 P J , expressed as:

[0141]

[0142] Its load rated power P ref The step response of the change can be expressed as:

[0143]

[0144] Where ΔP ref is the change in rated power of the load.

[0145] 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, which is equivalent to the function of synchronous machine characteristics. Its access structure and control effect are as follows: Figure 6 and Figure 7 shown.

[0146] The present invention first designs a photovoltaic self-reserve control scheme to improve the photovoltaic maximum power tracking control, so that the photovoltaic itself has the ability to adjust the grid droop and realize source-load adaptive matching; further, by analyzing the characteristics of the synchronous mechanism network, the rotor inertia power in the transient characteristics is decomposed, and the corresponding control algorithm is designed and applied to the energy storage control to coordinate the photovoltaic grid and give play to the flexible access characteristics of energy storage; finally, the simulation example verifies the synchronous grid-building capability of the self-reserve photovoltaic under the coordination of energy storage. This method effectively avoids the transformation of large-scale photovoltaics that have been applied, and at the same time realizes the flexible access of energy storage, which improves the reliability of power supply in remote rural grids with high self-sufficiency rate.

[0147] Another aspect of the present invention provides a self-backup photovoltaic energy storage collaborative grid control device, comprising:

[0148] The maximum power estimation module is used to evaluate the power information corresponding to the maximum power point of the photovoltaic array under the current operating condition to estimate the maximum power of the photovoltaic array;

[0149] The maximum power point tracking module is used to achieve the target self-reserve rate of photovoltaic power through variable step voltage tracking control: the estimated target self-reserve rate is obtained according to the estimated maximum power and output power of the photovoltaic array, the self-reserve rate error is obtained according to the target estimated self-reserve rate and the target self-reserve rate, and the voltage tracking convergence is adjusted by using the self-reserve rate error until it converges to the operating point corresponding to the target self-reserve rate, and some power is reserved for operation to provide the droop capability of photovoltaic grid construction;

[0150] 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.

[0151] 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;

[0152] The computer-readable storage medium is used to store executable instructions;

[0153] The processor is used to read the executable instructions stored in the computer-readable storage medium to execute the self-backup photovoltaic energy storage collaborative grid control method described in the first aspect.

[0154] Another aspect of the present invention provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the energy storage collaborative grid control method based on self-backup photovoltaics as described in the first aspect.

[0155] 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 adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0156] 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 box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes 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 generate 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.

[0157] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate 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 A function specified in one or more boxes.

[0158] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0159] 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 it. Although the present invention is described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation of the present invention can still be modified or replaced by equivalents, and any modification or equivalent replacement that does not deviate from the spirit and scope of the present invention should be included in 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 condition to estimate the maximum power of the photovoltaic array; Step 2: Use variable step size voltage tracking control to make the photovoltaic reach the target self-reserve rate: obtain the estimated self-reserve rate based on the maximum power and output power of the photovoltaic array estimated in step 1, obtain the self-reserve rate error based on the estimated self-reserve rate and the target self-reserve rate, and use the self-reserve rate error to adjust the voltage tracking convergence until it converges to the operating point corresponding to the target self-reserve rate, and reserve some power for operation to provide the photovoltaic grid droop capability; 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 regulation characteristics to participate in the grid construction.

2. The energy storage collaborative grid control method based on self-backup photovoltaic according to claim 1, characterized in that: Step 1 specifically includes: using an improved variable step-size small disturbance 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 disturbance observation scheme is expressed as: In the formula, Represents the variable step size adjustment coefficient; Indicates the output power of the photovoltaic array at time t; ΔU t Represents the voltage disturbance step length at time t.

3. The energy storage collaborative grid control method based on self-backup photovoltaic as claimed in claim 2 is characterized by: In step 1, the maximum power of the photovoltaic array is estimated, wherein 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 energy storage collaborative grid control method based on self-backup photovoltaic according to claim 3 is 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 energy storage collaborative grid control method based on self-backup photovoltaic according to claim 1, characterized in that: The variable step size voltage tracking control design in step 2 is: In the formula, Indicates the voltage reference value of the photovoltaic controller at time t, ΔU t represents the voltage disturbance step at time t, U Δ Adjust the step size for the selected voltage; dP / dU<0 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 return the operating point to the left side of the maximum power point. dP / dU≥0 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 change until it converges to the operating point corresponding to the self-reserve rate.

6. The energy storage collaborative grid control method based on self-backup photovoltaic according to claim 1, characterized in that: Step three specifically includes: According to the change of rotor speed of synchronous machine caused by unbalanced power, 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 Respectively represent the input power, electric power and damping power of the synchronous machine, where P D =D(ω m -ω n ), D is the equivalent damping coefficient of the synchronous machine, ω n is the rated angular speed 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 regulating valve; When the inverter end is modeled and the synchronous machine characteristics are realized, the inverter port output power P e It is expressed as: In the formula, E0, U l Respectively represent the no-load voltage and actual port voltage output by the inverter, Z f is the inverter filter impedance, Where L f , R f Respectively represent the filter inductance and filter resistance, α represents the 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: The rotor damping power is unified into the speed control equation, and 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 With 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: Its 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-support photovoltaic energy storage collaborative grid control device, characterized in that: include: The maximum power estimation module is used to evaluate the power information corresponding to the maximum power point of the photovoltaic array under the current operating condition 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 through variable step voltage tracking control: the target estimated self-reserve rate is obtained according to the estimated maximum power and output power of the photovoltaic array, the self-reserve rate error is obtained according to the target estimated self-reserve rate and the target self-reserve rate, and the voltage tracking convergence is adjusted by using the self-reserve rate error until it converges to the operating point corresponding to the target self-reserve rate, and some power is reserved for operation to provide the droop capability of photovoltaic grid construction; The inertia power control module is used to design a transient rotor inertia power control strategy based on the rotor inertia power loop of the synchronous mechanism network, so that the photovoltaic array with auxiliary self-backup droop regulation characteristics can participate in the grid construction.

8. The energy storage cooperative network control device based on self-backup photovoltaic according to claim 7, characterized in that: The inertia power control module is specifically used for: According to the change of rotor speed of synchronous machine caused by unbalanced power, 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 Respectively represent the input power, electric power and damping power of the synchronous machine, where P D =D(ω m -ω n ), D is the equivalent damping coefficient of the synchronous machine, ω n is the rated angular speed 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 regulating valve; When the inverter end is modeled and the synchronous machine characteristics are realized, the inverter port output power P e It is expressed as: In the formula, E0, U l Respectively represent the no-load voltage and actual port voltage output by the inverter, Z f is the inverter filter impedance, Where L f , R f Respectively represent the filter inductance and filter resistance, α represents the 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: The rotor damping power is unified into the speed control equation, and 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 With 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: Its 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-backup photovoltaic energy storage collaborative grid control system, comprising: A computer readable storage medium and a 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 to execute the self-backup photovoltaic-based energy storage collaborative grid control method described in any one of claims 1-6.

10. A non-transitory computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the energy storage collaborative grid control method based on self-backup photovoltaics as described in any one of claims 1 to 6.

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