A network-constructed energy storage stability optimization control method, system, device and medium

Abstract

The application discloses a network-constructing energy storage stability optimization control method, system, device and medium, relates to the technical field of power systems, and comprises the following steps: analyzing the system impedance characteristics of a power system on an electrical coordinate axis to determine a remodeling target, wherein the remodeling target comprises: q-axis impedance of network-constructing energy storage; constructing a control model of a network-constructing energy storage converter; introducing a compensation signal based on q-axis current into a q-axis voltage outer loop of the network-constructing energy storage based on the control model to remodel the q-axis impedance of the network-constructing energy storage; and superimposing the compensation signal on a q-axis voltage instruction value to form a final control instruction. The application solves the oscillation instability problem caused by network-constructing energy storage in a high-proportion new energy power system in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, and in particular to a grid-forming energy storage stability optimization control method, system, device and medium. BACKGROUND

[0002] Due to the randomness, volatility and intermittence of new energy power generation, and the influence of natural environment, the reliability of power supply is greatly reduced, and the energy supply and demand balance between power generation and power consumption is easily broken, requiring a large number of additional devices to maintain power stability. Therefore, energy storage devices have flourished, and energy storage devices have unique capabilities to transfer power and energy time distribution, and have become a key means to improve the static performance of conventional power generation and enhance the dynamic adaptability of new energy power generation. It is an indispensable part of modern power systems. Especially on the new energy side, the combined operation mode of new energy + energy storage provides strong support for low voltage ride through, smooth power output and active support of inertia and primary frequency modulation.

[0003] Among them, grid-forming energy storage is a frontier technology, the essence of which is to generate a constant AC voltage source through control of the converter, thereby obtaining similar operating characteristics to synchronous generators, to solve the problems of low inertia, low damping and weak voltage support in the current "double high" characteristic power system. The dq and qq impedances of grid-forming energy storage affect the pole distribution of the entire system, and thus affect the system stability. The existing typical grid-forming control dq term impedance is too small or the qq term impedance is too large, which will cause system oscillation instability, and no corresponding improvement measures are taken. Therefore, it is urgent to design a grid-forming energy storage stability optimization control method. SUMMARY

[0004] The present application provides a grid-forming energy storage stability optimization control method, system, device and medium, which is used to solve the oscillation instability problem caused by grid-forming energy storage in the existing high proportion of new energy power system.

[0005] Therefore, the first aspect of the present application provides a grid-forming energy storage stability optimization control method, which comprises:

[0006] The system impedance characteristics of the power system in the electrical coordinate axis are analyzed to determine the remodeling target, the remodeling target comprising: the qq axis impedance of the grid-forming energy storage;

[0007] A control model of the grid-forming energy storage converter is constructed, and based on the control model, a compensation signal based on the q-axis current is introduced in the q-axis voltage outer ring of the grid-forming energy storage to remodel the qq axis impedance of the grid-forming energy storage;

[0008] The compensation signal is superimposed on the q-axis voltage command value to form the final control command.

[0009] Optionally, the system impedance characteristics of the power system in the electrical coordinate axis are analyzed to determine the reshaping target, including:

[0010] The power system containing the MMC, the grid-following load, the grid-following new energy and the grid-following energy storage is constructed.

[0011] The partial derivatives of the dominant eigenvalues of the power system in the dq coordinate system to each impedance are calculated to generate a polar coordinate graph, wherein the each impedance includes the dd impedance, the dq impedance, the qd impedance and the qq impedance.

[0012] The direction and degree of the influence of the impedance change on the stability of the power system are shown through the polar coordinate graph to determine the reshaping target.

[0013] Optionally, the compensation signal based on the q-axis current is introduced, including:

[0014] The collected q-axis current signal of the grid-following energy storage is processed through a second-order band-pass filter to obtain a filtered output signal.

[0015] The filtered output signal is multiplied by a positive proportional coefficient Kr to generate the compensation signal.

[0016] Optionally, the center frequency of the second-order band-pass filter is set as the oscillation frequency of the power system.

[0017] Optionally, the oscillation frequency of the power system is set as 10 Hz, and the center frequency of the second-order band-pass filter is correspondingly set as 10 Hz.

[0018] Optionally, the value of the proportional coefficient Kr is adjusted according to the required stability margin of the system.

[0019] Optionally, the control model includes the power synchronization ring, the voltage ring, the current ring and the decoupling control.

[0020] The second aspect of the present application provides a grid-connected energy storage stability optimization control system, the system includes:

[0021] The analysis unit is used for analyzing the system impedance characteristics of the power system in the electrical coordinate axis to determine the reshaping target, and the reshaping target includes the qq-axis impedance of the grid-connected energy storage.

[0022] The first optimization unit is used for constructing the control model of the grid-connected energy storage converter, introducing a compensation signal based on the q-axis current in the q-axis voltage outer ring of the grid-connected energy storage based on the control model, and reshaping the qq-axis impedance of the grid-connected energy storage.

[0023] A second optimization unit is configured to superimpose the compensation signal on the q-axis voltage command value to form a final control command.

[0024] The third aspect of the present application provides a network-constructed energy storage stability optimization control device, the device comprising a processor and a memory:

[0025] The memory is configured to store program code and transmit the program code to the processor.

[0026] The processor is configured to execute the steps of the network-constructed energy storage stability optimization control method according to the instructions in the program code.

[0027] The fourth aspect of the present application provides a computer-readable storage medium for storing program code, the program code being used to execute the network-constructed energy storage stability optimization control method according to the first aspect.

[0028] From the above technical solutions, the present application has the following advantages:

[0029] The network-constructed energy storage stability optimization control method provided by the present application first deeply analyzes the system impedance characteristics and accurately points out that the real part of the q-axis impedance of the network-constructed energy storage is a key factor affecting system stability. Then, an additional control path based on a second-order band-pass filter is introduced in the q-axis voltage outer loop to realize impedance reshaping. The gain of the filter at the direct current component (i.e. the steady-state operating point) is zero, which means that the proposed control strategy only actively intervenes when the system is disturbed by oscillation, and does not affect the steady-state operation of the system. Moreover, this scheme is an improvement on the original control structure, without changing the main circuit topology, only adding the corresponding module in the software control algorithm, which is easy to integrate and promote on the existing network-constructed energy storage equipment. Further, the core parameters of the present application, such as the center frequency and the proportional coefficient Kr of the band-pass filter, can be flexibly adjusted according to the main oscillation mode of the actual system. In summary, the present application provides an efficient, reliable and easy-to-implement stability optimization scheme, which effectively solves the oscillation instability problem caused by the network-constructed energy storage in the high-proportion new energy power system in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0031] Figure 1A flowchart illustrating a method for optimizing and controlling the stability of grid-connected energy storage, provided in an embodiment of the present invention;

[0032] Figure 2 A schematic diagram showing the derivative results for different impedances provided in an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the control strategy for a grid-type energy storage converter provided in an embodiment of the present invention;

[0034] Figure 4 A schematic diagram illustrating the improved control of grid-type energy storage provided in an embodiment of the present invention;

[0035] Figure 5 This is a schematic diagram of a Bode plot of a bandpass filter provided in an embodiment of the present invention;

[0036] Figure 6 A schematic diagram comparing the equivalent impedance of the grid-type energy storage before and after the improved control provided in this embodiment of the invention;

[0037] Figure 7 A schematic diagram illustrating the changes in the Nyquist curve after improved control, provided in an embodiment of the present invention;

[0038] Figure 8 This is a schematic diagram of a grid-based energy storage stability optimization control system provided in an embodiment of the present invention. Detailed Implementation

[0039] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0040] Please see Figure 1 The present invention provides a method for optimizing and controlling the stability of grid-connected energy storage, comprising:

[0041] Step 101: Analyze the system impedance characteristics of the power system on the electrical coordinate axis to determine the reshaping target. The reshaping target includes the q-axis impedance of the grid-type energy storage.

[0042] In one embodiment, step 101 includes:

[0043] A power system comprising an MMC, a grid-following load, a grid-following new energy, and a grid-forming energy storage is constructed. Partial derivatives of dominant eigenvalues of the power system with respect to various impedances are calculated in a dq coordinate system to generate a polar coordinate diagram, wherein the various impedances include dd impedance, dq impedance, qd impedance, and qq impedance. The direction and degree of the effect of impedance changes on power system stability are exhibited through the polar coordinate diagram to reshape the target.

[0044] It should be noted that the system containing the modular multilevel converter (MMC) in the prior art, Figure 2 the grid-following load (GFLpq) in the prior art, Figure 2 the grid-following new energy (GFLvdc) in the prior art, Figure 2 and the grid-forming energy storage (GFM) in the prior art, Figure 2 the derivation results of the dominant eigenvalues of the system with respect to the impedances are exhibited in the polar coordinate system, as shown in Figure 2 , the effects of different impedances of the system can be further analyzed.

[0045] Figure 2 In the prior art, different arrow lengths represent different degrees of effect, and the direction of the arrow shows the change direction when the real part of a certain impedance is increased. It can be seen that the dq term impedance and the qq term impedance in the system have a key effect on the stability of the system. To increase the stability, the real part of the qq impedance of the MMC can be increased, the real part of the dq impedance of the grid-forming energy storage can be increased, the real part of the qq impedance of the grid-following new energy can be reduced, and the real parts of the dq and qq impedances of the grid-following load can be reduced. Considering that the converters of the new energy and the load generally belong to power stations and users, it is difficult to modify the control structure specifically, so the grid-forming energy storage is selected for optimization to improve the stability of the system. According to Figure 2 , it can be known that increasing the real part of the dq term impedance or reducing the imaginary part of the qq term can increase the stability. Considering that the coupling of the dq term may slow down the response speed of the controller of the system, the qq axis impedance of the system is finally selected for reshaping.

[0046] In step 102, a control model of the grid-forming energy storage converter is constructed, and based on the control model, a compensation signal based on the q-axis current is introduced in the q-axis voltage outer loop of the grid-forming energy storage to reshape the qq axis impedance of the grid-forming energy storage.

[0047] In one embodiment, the control model comprises a power synchronization loop, a voltage loop, a current loop, and decoupling control.

[0048] It should be noted that the control strategy of the classical grid-forming energy storage converter is as follows:

[0049] Grid-forming control synchronizes with the power grid, which imitates the rotor motion equation of the traditional synchronous generator, plays a key role in frequency stability and voltage stability, and the control strategy of the grid-forming energy storage converter is as shown in Figure 3 .

[0050] The synchronization of the grid-forming converter mainly relies on the virtual synchronous machine (VSG) module, which imitates the second-order rotor equation of the synchronous generator and has virtual inertia and damping characteristics. Its synchronization equation is as follows:

[0051] (1)

[0052] Where ω gfm is the grid-forming energy storage angular frequency, θ gfm is the grid-forming energy storage output power angle, J is the virtual inertia coefficient, D p is the virtual droop coefficient, P refgfm is the active power command value, P gfm is the detected output power of the converter, w0 is the rated speed of the virtual synchronous machine, which is 314 prad / s. The calculation method of the active power P gfm of the system is as follows:

[0053] (2)

[0054] Where U gfm_d , U gfm_q , I gfm_d , I gfm_q are the sampling values in the controller coordinate system. The voltage control of the system includes a voltage control loop and a current control loop, and its control equation is as follows:

[0055] (3)

[0056] (4)

[0057] Where I dref_gfm , I qref_gfm are the d-axis and q-axis current reference values of the grid-forming energy storage controller current inner loop, V dc is the DC side voltage, V dcref is the DC side voltage reference value, H v_gfm (s) is the controller of the AC voltage control loop, H i2 (s) is the controller of the current control loop, k pv2 , k iv2 and k pc2 , k ic2 are H v_gfm (s) and H i2The ratio and integral coefficient of (s).U ref is the specified value of the system AC voltage, and the specified voltage of the q-axis is 0.k dei is the decoupling coefficient of current decoupling, which is generally set to 1. The modulation part, because the DC side circuit is simplified to a constant voltage source, V dc is equal to V dcref , that is, V dc is always V dcref =1. The equation of the circuit part is:

[0058] (5)

[0059] In the expression, s is the differential symbol in the frequency domain, L f2 represents the filter inductance of the network-forming energy storage converter, V od2 and V oq2 represent the d-axis and q-axis output voltages of the converter port in the system coordinate system, respectively.

[0060] Further, it needs to be explained that the impedance modeling of the classical network-forming energy storage converter is as follows:

[0061] The controller coordinate system and the system coordinate system have a certain conversion relationship, and the active power disturbance detected in the controller is:

[0062] (6)

[0063] In the expression, U s gfm_d , U s gfm_q , I s gfm_d , I s gfm_q is the steady-state voltage and current in the dq coordinate system when the system is stable, , , , is the disturbance of the voltage and current in the controller coordinate system, G PU and G PI represent the transfer functions of the voltage and current in the controller coordinate system to the power disturbance, and the linearization of (1) can obtain the disturbance of the phase angle and the active power:

[0064] (7)

[0065] In the formula, Δω gfm is the angular frequency disturbance, is the phase angle disturbance, and s is the differential symbol in the frequency domain.

[0066] After being solved together, we can obtain:

[0067] (8)

[0068] In the formula, This is the transfer function from power disturbance to phase angle disturbance.

[0069] The relationship between voltage and current disturbances in the controller coordinate system and voltage and current disturbances in the system coordinate system is as follows:

[0070] (9)

[0071] In the formula, These are the transfer functions from the phase angle disturbance in the system coordinate system to the voltage and current disturbances in the controller coordinate system and the voltage disturbance at the output terminal in the system coordinate system, respectively. , These represent the d-axis and q-axis output voltage disturbances at the ports of the grid-type energy storage converter in the control coordinate system. , These represent the output voltage disturbances at the ports of the grid-connected energy storage converter along the d-axis and q-axis in the system coordinate system. and These are the voltage disturbances along the d-axis and q-axis at the grid connection point in the system coordinate system. and It is the current disturbance at the grid connection point in the system coordinate system.

[0072] Combine (6), (8), and (9) into a single equation and substitute the result into U. s gfm_q =0, we can find:

[0073] (10)

[0074] In the formula, Let be the transfer function from the current disturbance to the phase angle disturbance in the controller coordinate system. This is the transfer function from voltage disturbance to phase angle disturbance in the controller coordinate system.

[0075] Will Substituting the result into (9), we can simplify it to:

[0076] (11)

[0077] In the formula, G UU It is the voltage transfer function in the system coordinate system and the voltage transfer function in the control coordinate system, G. IU It is the transfer function of current in the control coordinate system and voltage in the system coordinate system, G. VoU It is the voltage transfer function between the output terminal voltage in the system coordinate system and the voltage in the system coordinate system, G. UIis the voltage transfer function of the system coordinate system and the control coordinate system, G II is the current transfer function of the control coordinate system and the system coordinate system, G VoU is the output voltage transfer function of the system coordinate system and the system coordinate system. is the disturbance of the output voltage in the system controller coordinate system. I is an identity matrix. Linearization of (3) and (4) can obtain the disturbance of the voltage and current disturbances to the output voltage in the controller coordinate system:

[0078] (12)

[0079] (13)

[0080] In the formula, k dei represents the decoupling coefficient of the current loop, G ci2 represents the transfer function of the current outer loop output disturbance to the grid point voltage disturbance, G dei2 represents the transfer function of the current disturbance to the grid point voltage disturbance, G v represents the transfer function of the voltage disturbance in the controller coordinate system to the current disturbance in the controller coordinate system.

[0081] (11) (12) (13) are combined with the circuit equation, and the filter impedance is represented by Z l2 , the equivalent impedance of the grid-connected energy storage converter can be finally obtained as:

[0082] (14)

[0083] In the formula, is the grid point voltage disturbance in the system coordinate system, is the grid point current disturbance in the system coordinate system, both of which contain d-axis and q-axis corresponding components.

[0084] It can be understood that the control model of the grid-connected energy storage converter is determined by constructing the control strategy of the classical grid-connected energy storage converter and the impedance of the classical grid-connected energy storage converter, which is used for subsequent analysis of system stability and design of optimized control strategy. Based on this, the grid-connected energy storage stability optimization control system aims to solve the problems of the system being easily affected by the change of grid impedance and the lack of stability margin under the traditional control structure by introducing an impedance reshaping control mechanism, so as to improve the operation stability of the grid-connected energy storage system under different working conditions.

[0085] In one embodiment, a compensation signal based on the q-axis current is introduced, including:

[0086] ​The q-axis current signal of the network-constructed energy storage collected is processed by a second-order band-pass filter to obtain a filtered output signal; the filtered output signal is multiplied by a positive proportional coefficient Kr to generate the compensation signal.

[0087] Further, the center frequency of the second-order band-pass filter is set as the oscillation frequency of the power system, the oscillation frequency of the power system is set as 10 Hz, and the center frequency of the second-order band-pass filter is correspondingly set as 10 Hz. The value of the proportional coefficient Kr is adjusted according to the required stability margin of the system.

[0088] In step 103, the compensation signal is superimposed on the q-axis voltage command value to form a final control command.

[0089] It should be noted that for the remodeling of the qq-axis impedance of the network-constructed energy storage in steps 102 and 103, please refer to Figure 4 .

[0090] Based on the control model constructed in step 102, specifically, by changing the voltage command value of the q-axis voltage outer loop, the voltage of the q-axis is linked to the q-axis current, thereby improving the self-impedance of the qq-axis (i.e., introducing a compensation signal based on the q-axis current). Through analysis, it is known that the oscillation frequency of the power system is 10 Hz, and the oscillation frequency under different working conditions fluctuates between 8-14 Hz, so for this frequency band, a second-order band-pass filter is set to screen the disturbance. The control parameters and the Bode plot of the transfer function of the second-order band-pass filter are shown in Table 1 and Figure 5 .

[0091] Table 1 Second-order band-pass filter parameters

[0092]

[0093] Further, to enhance the control's ability to suppress oscillation, the center frequency of the filter is selected as the oscillation frequency. At the same time, to ensure that the proposed control does not affect too many frequency bands, the bandwidth of the second-order band-pass filter is set to 10 Hz. In addition, the amplitude response of the second-order transfer function to the direct current component is 0, indicating that the steady-state operating point of the system will not be affected after the control is added. At the oscillation corresponding to 10 Hz, the phase angle of the band-pass filter is 0 degrees, meaning that at this frequency, the added control is equivalent to adding a virtual negative resistance with a value of K rl to the q-axis circuit, reducing the real part value of the qq equivalent impedance of the network-constructed energy storage and improving the stability of the system.

[0094] The following is an analysis and simulation description of the improved power system impedance:

[0095] The equivalent impedance of the network-constructed energy storage after adding the improved control is:

[0096] (15)

[0097] In the formula, the second row of the denominator of the molecule is the part affected by the improvement control. Considering that the band-pass filter only affects the q-axis current to the q-axis voltage command value, the transfer function of the band-pass filter part is:

[0098] (16)

[0099] Due to the phase angle disturbance of the synchronization ring, the q-axis current collected by the system is jointly affected by the dq-axis voltage and current disturbance. Therefore, in addition to the q-axis self-impedance, the remaining impedances also change.

[0100] In order to evaluate this change, a detailed analysis of the impedance characteristics of the system before and after the improvement is needed. The impedances of the system before and after the addition of the improvement control are shown in Figure 6 It can be found that for the dd and qd terms, the impedances of the system before and after the addition of the improvement control have hardly changed. However, for the dq and qq terms, the introduction of the improvement control has not significantly changed the phase angle, but the amplitude has been significantly reduced. Further analysis of the change in the real part of the impedance shows that the phase angle of the dq term impedance is close to -180 degrees, and the reduction in the amplitude represents an increase in the real part of the term. At the same time, for the qq impedance, the phase angle is close to 0 degrees, and the reduction in the amplitude represents a decrease in the real part of the impedance. Increasing the real part of the dq term and decreasing the real part of the qq term together promote the improvement of the system stability.

[0101] The Nyquist curve of G(s) after the addition of the improvement control is drawn to observe the change in the stability margin of the system after the change in the impedance, and the results are shown in Figure 7 For the eigenvalue , the Nyquist curve corresponding to the eigenvalue does not change before and after the addition of the control. However, the intersection point of the curve corresponding to the eigenvalue with the negative real axis changes from -0.96 to -0.75, and the amplitude margin is improved by 0.21, verifying the improvement of the stability due to the change in the impedance.

[0102] From a qualitative point of view, the stability improvement result of the control is analyzed. The main reason for the instability of the grid-forming device is that its electrical distance from the ideal voltage source is too far, the voltage loses support, and the system oscillates and becomes unstable. Reducing the qq impedance and the dq impedance amplitude essentially reduces the output impedance of the grid-forming converter, reduces the distance of the grid-forming equivalent voltage source from the grid point, and reduces the electrical distance of the grid-forming new energy converter from the ideal voltage source, thereby improving the system stability.

[0103] The analysis results are verified in the time domain simulation, as shown in Figure 7As shown. At simulation time t=10s, the reactive power command value Q to the grid-type load is... ref Add a perturbation with an amplitude of 0.01 pu to the input and observe different K values. r The variation of d-axis voltage and output frequency f of the energy storage system under the given values. When K r When K = 0, the improved control is essentially masked, meaning the system reverts to the original control strategy. Compare different K values. r The perturbation result under the value, when K r The smaller K is, the larger the oscillation amplitude of the system and the slower the decay rate; when K r The larger the value of , the faster the system's oscillations decay and the sooner it reaches steady state. The results of time-domain simulations verify the results of the Nyquist curve analysis, demonstrating the stability-enhancing effect of the proposed control.

[0104] This invention provides a stability optimization control method for grid-connected energy storage. First, it analyzes the system impedance characteristics in depth, accurately identifying the real part of the q-axis impedance of the grid-connected energy storage as the key factor affecting system stability. Then, it achieves impedance reshaping by introducing an additional control path based on a second-order bandpass filter into the outer loop of the q-axis voltage. This filter has zero gain at the DC component (i.e., the steady-state operating point), meaning that the proposed control strategy only intervenes actively when the system experiences oscillations or disturbances, without affecting the system's steady-state operation. Furthermore, this scheme is an improvement on the existing control structure, requiring no changes to the main circuit topology; only the addition of a corresponding module to the software control algorithm is needed, making it easy to integrate and widely apply on existing grid-connected energy storage devices. Furthermore, the core parameters of this invention, such as the center frequency of the bandpass filter and the proportional coefficient Kr, can be flexibly tuned according to the main oscillation mode of the actual system. (For example, setting the filter center frequency to the observed dominant oscillation frequency (e.g., 10Hz) can effectively suppress oscillations in that frequency band.) By adjusting the value of the proportional coefficient Kr, the intensity of impedance reshaping can be linearly adjusted, thereby achieving flexible and smooth adjustment of the system damping effect to meet the differentiated stability requirements under different system conditions. In summary, this invention provides an efficient, reliable, and easy-to-implement stability optimization scheme that effectively solves the oscillation instability problem caused by grid-based energy storage in high-proportion new energy power systems in existing technologies.

[0105] The above is a method for optimizing the stability of grid-connected energy storage provided in the embodiments of the present invention. The following is a method for optimizing the stability of grid-connected energy storage provided in the embodiments of the present invention.

[0106] Please see Figure 8 The present invention provides a grid-based energy storage stability optimization control system, comprising:

[0107] The analysis unit 201 is configured to analyze system impedance characteristics of the power system in electrical coordinate axes to determine remodeling targets, the remodeling targets including: q-axis impedance of the grid-forming energy storage;

[0108] The first optimization unit 202 is configured to construct a control model of the grid-forming energy storage converter, and introduce a compensation signal based on the q-axis current into a q-axis voltage outer loop of the grid-forming energy storage based on the control model, so as to remodel the q-axis impedance of the grid-forming energy storage.

[0109] The second optimization unit 203 is configured to superimpose the compensation signal on a q-axis voltage instruction value to form a final control instruction.

[0110] Further, the embodiment of the present application further provides a grid-forming energy storage stability optimization control device, the device comprising a processor and a memory:

[0111] The memory is configured to store program code and transmit the program code to the processor.

[0112] The processor is configured to execute steps of the grid-forming energy storage stability optimization control method according to instructions in the program code.

[0113] Further, the embodiment of the present application further provides a computer readable storage medium, the computer readable storage medium is configured to store program code, and the program code is configured to execute the method described in the above method embodiments.

[0114] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described system and unit can refer to the corresponding process in the foregoing method embodiments, which will not be repeated here.

[0115] In several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. For example, the above-described device embodiments are only schematic, for example, the division of units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the shown or discussed mutual units can be indirect coupling or communication connection through some interfaces, devices or units, and can be electrical, mechanical or other forms.

[0116] The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, i.e., may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment scheme.

[0117] In addition, each functional unit in each embodiment of the application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0118] If the integrated unit is realized in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the application or the part of the prior art that contributes essentially or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method of each embodiment of the application. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0119] The above embodiments are only used to illustrate the technical solutions of the application, but not to limit them; although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. A method for stability optimization control of network-constructed energy storage, characterized in that, The method comprises the following steps: analyzing the system impedance characteristics of the power system in the electrical coordinate axis to determine the reshaping target, the reshaping target comprising: the qq-axis impedance of the grid-connected energy storage; building a control model of the grid-connected energy storage converter, and introducing a compensation signal based on the q-axis current into the q-axis voltage outer loop of the grid-connected energy storage based on the control model, so as to reshape the qq-axis impedance of the grid-connected energy storage; superimposing the compensation signal on the q-axis voltage instruction value to form a final control instruction; the analysis of the system impedance characteristics of the power system in the electrical coordinate axis to determine the reshaping target comprises: building a power system comprising MMC, grid-following load, grid-following new energy and grid-following energy storage; calculating the partial derivatives of the dominant eigenvalues of the power system with respect to various impedances in the dq coordinate system to generate a polar coordinate graph, wherein the various impedances comprise: dd impedance, dq impedance, qd impedance and qq impedance; determining the reshaping target by showing the direction and degree of the influence of the impedance change on the stability of the power system through the polar coordinate graph; the introduction of the compensation signal based on the q-axis current comprises: processing the collected q-axis current signal of the grid-connected energy storage through a second-order band-pass filter to obtain a filtered output signal; multiplying the filtered output signal by a positive proportional coefficient Kr to generate the compensation signal.

2. The network-constructed energy storage stability optimization control method of claim 1, wherein The center frequency of the second-order band-pass filter is set as the oscillation frequency of the power system.

3. The network-configuration energy-storage stability optimization control method of claim 2, wherein, The oscillation frequency of the power system is set as 10 Hz, and the center frequency of the second-order band-pass filter is correspondingly set as 10 Hz.

4. The network-constructed energy storage stability optimization control method of claim 1, wherein The value of the proportional coefficient Kr is adjusted according to the required stability margin of the system.

5. The network-constructed energy storage stability optimization control method of claim 1, wherein The control model comprises a power synchronization loop, a voltage loop, a current loop and a decoupling control.

6. A network-configuration energy storage stability optimization control system, characterized in that, The method comprises the following steps: an analysis unit is configured to analyze the system impedance characteristics of the power system in the electrical coordinate axis to determine the reshaping target, the reshaping target comprising: the qq-axis impedance of the grid-connected energy storage; a first optimization unit is configured to build a control model of the grid-connected energy storage converter, and introduce a compensation signal based on the q-axis current into the q-axis voltage outer loop of the grid-connected energy storage based on the control model, so as to reshape the qq-axis impedance of the grid-connected energy storage; a second optimization unit is configured to superimpose the compensation signal on the q-axis voltage instruction value to form a final control instruction; the analysis of the system impedance characteristics of the power system in the electrical coordinate axis to determine the reshaping target comprises: building a power system comprising MMC, grid-following load, grid-following new energy and grid-following energy storage; calculating the partial derivatives of the dominant eigenvalues of the power system with respect to various impedances in the dq coordinate system to generate a polar coordinate graph, wherein the various impedances comprise: dd impedance, dq impedance, qd impedance and qq impedance; determining the reshaping target by showing the direction and degree of the influence of the impedance change on the stability of the power system through the polar coordinate graph; the introduction of the compensation signal based on the q-axis current comprises: processing the collected q-axis current signal of the grid-connected energy storage through a second-order band-pass filter to obtain a filtered output signal; The filtered output signal is multiplied by a positive scaling factor Kr to generate the compensation signal.

7. A network-configuration energy storage stability optimization control device, characterized by, The device comprises a processor and a memory: The memory is configured to store program code and transmit the program code to the processor; The processor is configured to execute the network construction energy storage stability optimization control method according to the instructions in the program code.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium is configured to store program code, and the program code is configured to execute the network construction energy storage stability optimization control method.

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