Voltage and frequency regulation method, device, equipment, medium and product of island power grid of network construction type energy storage system

Abstract

The invention discloses a voltage and frequency regulation method, device, equipment, medium and product for a network-construction-type energy storage system island power grid, and relates to the field of novel power system control, the method comprises the following steps: introducing virtual impedance at the output end of the network-construction-type energy storage system island power grid, and superposing virtual voltage drop to form virtual power; inputting the virtual power into a VSG power control ring, performing decoupling control on the active power and the reactive power, and determining the decoupled virtual power; the VSG power control loop comprises an active power control loop and a reactive power control loop; based on the decoupled virtual power, constructing an active frequency control loop of the VSG, and performing indifference adjustment on the frequency; a VGS reactive voltage control loop is constructed based on the decoupled virtual power, a self-adaptive droop coefficient and self-adaptive adjustment voltage are introduced into the reactive voltage control loop based on the reactive capacity of the isolated island power grid of the network construction type energy storage system, the virtual power can be solved, and the potential that the reactive capacity of the energy storage system supports voltage adjustment is brought into full play.

Description

Technical Field

[0001] The present application relates to the field of new power system control, and particularly to a voltage regulation and frequency modulation method, device, equipment, medium and product for an island power grid of a grid-forming energy storage system. Background Art

[0002] As a frontier technology for renewable energy, island power grids have been widely applied to new power systems with a high proportion of clean energy. At the same time, due to the small scale of island power grids and their small inherent inertia, once the connection channels are disconnected, the imbalance of active power will lead to the frequency instability of the island power grid. The power system usually adopts emergency interlocking generator tripping or centralized load shedding control measures. If the emergency control measures fail or the control amount is insufficient, it may cause the instability of the island power grid. With the development of grid-forming technology, energy storage can be connected in the form of grid-forming control to provide transient frequency / voltage support for the island power grid. The energy storage system has a fast response speed and can quickly and accurately track the active power command of the system. Through the optimized design of the control system, fast and continuous active power support can be achieved.

[0003] There are currently various frequency modulation and voltage regulation control methods for energy storage systems. To achieve decoupled regulation of active and reactive power, the most commonly used method is to introduce a virtual negative impedance at the output end of the energy storage converter to alleviate the power control coupling phenomenon. However, no clear method for setting the virtual impedance value is given, and the calculation method is complex. The influence of the output power angle of the energy storage system on power coupling is not considered, and there is a lack of evaluation index for the degree of power coupling. At the same time, for the droop control of voltage regulation in island power grids, only the influence of the droop coefficient on the maximum power tracking of wind power and photovoltaic power generation and the reactive power margin adaptation of wind power generation are considered. The reactive power regulation capacity of the energy storage system under the operation of the island power grid is not considered separately, and thus the self-adaptive voltage regulation potential of the energy storage system cannot be exerted. Summary of the Invention

[0004] The purpose of the present application is to provide a voltage regulation and frequency modulation method, device, equipment, medium and product for an island power grid of a grid-forming energy storage system to solve the problems of lack of power coupling degree and inability to exert the self-adaptive voltage regulation potential of the energy storage system.

[0005] To achieve the above purpose, the present application provides the following solutions:

[0006] In a first aspect, the present application provides a voltage regulation and frequency modulation method for an island power grid of a grid-forming energy storage system, including:

[0007] Introduce a virtual impedance at the output end of the island power grid of the grid-forming energy storage system, and form a virtual power by superimposing a virtual voltage drop.

[0008] Input the virtual power into the VSG power control loop to decouple and control the active power and reactive power, and determine the decoupled virtual power; the VSG power control loop includes an original active power control loop and an original reactive voltage control loop;

[0009] Based on the decoupled virtual power, construct an active frequency control loop of the VSG to perform zero-error regulation on the frequency;

[0010] Based on the decoupled virtual power, construct a reactive voltage control loop of the VGS, and introduce an adaptive droop coefficient into the reactive voltage control loop based on the reactive power capacity of the grid-connected energy storage system island grid to adaptively regulate the voltage.

[0011] In a second aspect, the present application provides a voltage and frequency regulation device for a grid-connected energy storage system island grid, including:

[0012] A virtual power formation module, configured to introduce a virtual impedance at the output end of the grid-connected energy storage system island grid, and form virtual power by superimposing a virtual voltage drop;

[0013] A decoupling module, configured to input the virtual power into the VSG power control loop to decouple and control the active power and reactive power, and determine the decoupled virtual power; the VSG power control loop includes an original active power control loop and an original reactive voltage control loop;

[0014] A frequency error regulation module, configured to construct an active frequency control loop of the VSG based on the decoupled virtual power to perform zero-error regulation on the frequency;

[0015] A voltage regulation module, configured to construct a reactive voltage control loop of the VGS based on the decoupled virtual power, and introduce an adaptive droop coefficient into the reactive voltage control loop based on the reactive power capacity of the grid-connected energy storage system island grid to adaptively regulate the voltage.

[0016] In a third aspect, the present application provides a computer device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor executes the computer program to implement the voltage and frequency regulation method for the grid-connected energy storage system island grid described in any one of the above.

[0017] In a fourth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the voltage and frequency regulation method for the grid-connected energy storage system island grid described in any one of the above.

[0018] In a fifth aspect, the present application provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the voltage and frequency regulation method for the grid-connected energy storage system island grid described in any one of the above.

[0019] According to the specific embodiments provided by the present application, the following technical effects are disclosed in the present application:

[0020] In the present application, virtual power is introduced into the power control loop of the virtual synchronous generator (VSG), so that the active frequency and reactive voltage control are decoupled, and the coupling coefficient of the active and reactive power output by the VSG is introduced, including the coupling coefficient of the reactive power output to the active power output and the coupling coefficient of the active power output to the reactive power output, to solve the virtual power; an undifferentiated angular frequency adjustment link is introduced into the VSG active frequency control loop, and an adaptive droop coefficient is introduced into the original VSG reactive voltage control loop, and the droop coefficient of the VSG reactive voltage control loop is dynamically adjusted according to the reactive power capacity of the energy storage system, so as to fully exert the potential of the reactive power capacity of the energy storage system to support voltage adjustment. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 It is a flow chart of the voltage regulation and frequency modulation method for the island power grid of the grid-connected energy storage system provided by the present application;

[0023] Figure 2 It is a control block diagram of the virtual power control strategy adopted by the present application;

[0024] Figure 3 It is a main circuit diagram of the grid-connected energy storage system provided by the present application and a structure diagram of active / frequency and reactive / voltage control;

[0025] Figure 4 It is a flow chart of the island power grid frequency and voltage support based on the voltage regulation and frequency modulation method for the island power grid of the grid-connected energy storage system provided by the present application. Detailed Embodiments

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0027] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] The embodiment of the present application provides a voltage and frequency regulation method for an island power grid of a network-forming energy storage system. This method is executed by a computer device, which can be specifically executed by a computer device such as a terminal or a server alone, or jointly executed by a terminal and a server. In the embodiment of the present application, as Figure 1 shown, this method includes the following steps.

[0029] A voltage and frequency regulation method for an island power grid of a network-forming energy storage system, the voltage and frequency regulation method for the island power grid of the network-forming energy storage system includes:

[0030] S1: Introduce a virtual impedance at the output end of the island power grid of the network-forming energy storage system, and form a virtual power by superimposing a virtual voltage drop.

[0031] S2: Input the virtual power into the VSG power control loop, perform decoupling control on the active power and reactive power, and determine the decoupled virtual power; the VSG power control loop includes an original active power control loop and an original reactive voltage control loop.

[0032] S3: Based on the decoupled virtual power, construct an active frequency control loop of the VSG to perform non-offset regulation on the frequency.

[0033] S4: Based on the decoupled virtual power, construct a reactive voltage control loop of the VGS, and introduce an adaptive droop coefficient into the reactive voltage control loop based on the reactive power capacity of the island power grid of the network-forming energy storage system to adaptively regulate the voltage.

[0034] In an exemplary embodiment, S1 can be replaced by the following steps.

[0035] S11: Determine the coupling coefficient of reactive power output to active power output and the coupling coefficient of active power output to reactive power output according to the virtual impedance.

[0036] S12: Determine the VSG output coupling coefficient according to the coupling coefficient of reactive power output to active power output and the coupling coefficient of active power output to reactive power output.

[0037] S13: When the VSG output coupling coefficient is the minimum value, calculate the virtual inductance value according to the resistance and reactance of the virtual impedance.

[0038] S14: Based on the virtual inductance value, determine the line impedance value after superimposing the virtual impedance according to the resistance and the reactance.

[0039] S15: Based on the Park transformation, obtain the VSG output current components, and calculate the virtual voltage drop according to the VSG output current components; the VSG output current components include the current d-axis component and the current q-axis component.

[0040] S16: Based on the line impedance value, superimpose the virtual voltage drop generated by the virtual impedance and the original VSG output voltage to form the VSG output virtual voltage value.

[0041] S17: Input the virtual voltage value and the VSG output current components into the power calculation module to determine the virtual power.

[0042] In practical applications, the virtual power decoupling control specifically includes: introducing a virtual impedance at the output end of the grid-forming energy storage system, forming a virtual power by superimposing the virtual voltage drop, and realizing the decoupling control of the active power and the reactive power.

[0043] The steps are as follows:

[0044] Calculate the parameters of the virtual impedance (resistance Rv and inductance Lv) to ensure that the active power and the reactive power can be effectively decoupled.

[0045] Through the Park transformation, obtain the d-axis and q-axis components (i q and i d ) of the VSG output current, and calculate the virtual voltage drops (V dv and V qv ).

[0046] Superimpose the virtual voltage drop and the original VSG output voltage to form the virtual voltage values (V dv ’ and V qv ’) of the VSG.

[0047] Send the virtual voltage value and the output current components into the power calculation module together to obtain the virtual power (P V and Q V ), and send them into the active and reactive control loops of the VSG.

[0048] Logic description: Through virtual power decoupling, provide an independent adjustment basis for subsequent active frequency and reactive voltage control, and avoid mutual interference between the two.

[0049] In practical applications, to achieve the decoupling control of the energy storage system under island operation, it specifically includes:

[0050] Considering that both the VSG output voltage and the power angle have an impact on the coupling degree of the power output, introduce the coupling degree. The relationship between the VSG output power, the electromotive force E, and the power angle δ is as follows:

[0051]

[0052] In the formula, P and Q are the output powers of the VSG, P is the active power, Q is the reactive power, and Z g is the line impedance at the connection point between the VSG output port and the island power grid, and U g is the voltage at the outlet of the islanded microgrid, and θ zg is the line impedance angle.

[0053] After introducing the virtual impedance, the impedance of the VSG output port is superimposed with the virtual impedance. The ratio of the derivative of the output active power with respect to the power angle to the derivative of the output active power with respect to the voltage is the coupling coefficient K of the reactive power output with respect to the active power output p , and the ratio of the derivative of the output reactive power with respect to the power angle to the derivative of the output reactive power with respect to the voltage is defined as the coupling coefficient K of the active power output with respect to the reactive power output Q , and the specific formula is as follows:

[0054]

[0055] In the formula, s is the complex frequency domain variable after Laplace transform. When the VSG is in a steady state and the per-unit value of the variable is taken, E≈0, and the VSG output coupling coefficient is obtained:

[0056]

[0057] By making the coupling coefficient K1 take the minimum value, the resistance part R v and the reactance X v of the virtual impedance can be obtained. Through the value of the virtual reactance, the value of the virtual inductor can be further calculated:

[0058]

[0059] ω n is the rated angular frequency of the power grid.

[0060] The line impedance value Zs after superimposing the virtual impedance is obtained:

[0061] Z s =(R + R v ) + j(X + X v )

[0062] R and L are the resistance and inductance parts of the line impedance at the VSG outlet, and R v and L v are the resistance and inductance parts of the added virtual impedance; j is the imaginary part of the impedance.

[0063] The virtual voltage drop generated by the virtual impedance is superimposed with the original VSG output voltage to form the p and q components V dv ’ and V qv ’ of the VSG output virtual voltage value, as shown in the following formula:

[0064]

[0065] wherein, i Ld and i Lq are the d-axis and q-axis components of the VSG output current after Park transformation, ω0 is the rated angular frequency taken as 100π. Before the virtual impedance is superimposed on the VSG, the voltage at the grid connection point is obtained through Park transformation to get V d and V q .

[0066] As Figure 2 shown, the virtual voltage value output by the VSG and the d-axis and q-axis components i q and i d of the island power grid side current are sent into the power calculation module together to obtain the virtual power P V and Q V , and the formula is as follows: They are sent into the active and reactive control loops of the VSG.

[0067]

[0068] According to the resistance and inductance parameters at the VSG outlet, the carrier signal frequency f c is obtained. From ω c = 2πf c , the filtering angular frequency ω c is obtained.

[0069] As Figure 3 shown, the virtual power output by the VSG is sent into the active and reactive control loops of the VSG.

[0070] In an exemplary embodiment, S12 can be replaced by the following steps.

[0071] Use to determine the VSG output coupling coefficient; wherein, K1 is the VSG output coupling coefficient; K p is the coupling coefficient of reactive power output to active power output; K Q is the coupling coefficient of active power output to reactive power output; R v is the resistance; X v is the reactance; δ is the power angle.

[0072] In an exemplary embodiment, S3 can be replaced by the following steps.

[0073] S31: Real-time collect the frequency fluctuations of the load side of the island power grid of the network-forming energy storage system, and calculate the active power regulation deviation through the active control loop based on the decoupled virtual power.

[0074] S32: Superimpose the active power regulation deviation on the active power output command value of the VSG, and dynamically adjust the active power output of the island power grid of the grid-forming energy storage system through the mechanical rotor equation of the VSG synchronous generator.

[0075] S33: Based on the active power output, construct an active power frequency control loop for the VSG, and add a zero-difference angular frequency regulation link to the active power frequency control loop of the VSG to correct the active power command value and perform zero-difference regulation on the frequency.

[0076] In practical applications, constructing the active power frequency control loop specifically includes: Based on the decoupled virtual power, separately construct the active power frequency control loop of the VSG to achieve zero-difference regulation of the frequency.

[0077] The steps are as follows:

[0078] Collect the frequency fluctuations on the load side of the island power grid in real time, and calculate the active power regulation deviation through a proportional-integral (PI) control link.

[0079] Superimpose the active power deviation on the active power output command value of the VSG, and dynamically adjust the active power output of the energy storage system through the mechanical rotor equation of the VSG synchronous generator. The mechanical rotor equation of the VSG synchronous generator is as follows:

[0080]

[0081] In the formula, the subscripts d and q respectively represent the d-axis and q-axis components after Park transformation, P m is the virtual mechanical power of the energy storage system, P e is the electromagnetic power output by the energy storage system, ω VSG is the virtual angular frequency of the energy storage system, ω g is the angular frequency of the island power grid, P ref is the active power command value, K f is the active power frequency droop ratio coefficient, U dv and U qv are respectively the d-axis and q-axis components of the grid-side voltage of the energy storage converter after virtual power decoupling, i d and i q are respectively the d-axis and q-axis components of the grid-side current of the energy storage converter. J and D P are respectively the virtual moment of inertia and damping coefficient of the energy storage system.

[0082] Add a zero-difference angular frequency regulation link to the active power frequency control loop of the VSG to correct the active power command value (P ref ), and ensure the zero-difference of frequency regulation.

[0083] Logical description: Through the active frequency control loop, the active power output of the energy storage system is dynamically adjusted to cope with the frequency fluctuations of the island power grid, ensuring the stability and zero-error of the frequency.

[0084] In practical applications, a VSG active frequency control loop is constructed, which specifically includes the following steps.

[0085] First, determine the parameters of the VSG active control loop. The inertia is determined by the following formula:

[0086]

[0087] First, determine the specified value of the active power output of the grid-forming energy storage system and the allowable maximum frequency deviation, f n Take 50 Hz to obtain the damping coefficient D p , and the maximum frequency deviation Δf can be set according to the frequency regulation requirements of the energy storage system max , and then calculate the moment of inertia J according to the time coefficient τ of the energy storage output power f

[0088] As Figure 3 shown, in the VSG active loop, the basic control structure of the active frequency control loop is built according to the mechanical rotor equation of the virtual synchronous generator.

[0089] As Figure 3 shown, a frequency zero-error control link is added to the active power output specified link of the active loop. The frequency feedback of the VSG is fed back and the active power output specified deviation is calculated through the zero-error regulation control link, as follows:

[0090]

[0091] After being corrected by the zero-error frequency regulation, the VSG active control loop is as follows:

[0092] P r ′ ef = P ref + ΔP

[0093] In an exemplary embodiment, S4 can be replaced by the following steps.

[0094] S41: Dynamically collect the active power output of the grid-forming energy storage system in the island power grid, and calculate the reactive power capacity of the grid-forming energy storage system in the island power grid based on the decoupled virtual power, according to the apparent power and the active power output of the grid-forming energy storage system in the island power grid.

[0095] S42: Determine the upper and lower limits of the reactive power according to the reactive power capacity, in combination with the charge and discharge state of the grid-forming energy storage system in the island power grid.

[0096] ​S43: Based on the upper and lower limits of the reactive power, construct a reactive voltage control loop for VGS.

[0097] S44: Dynamically adjust the droop coefficient of the reactive voltage control loop of VGS according to the reactive power capacity, correct the voltage regulation equation, and determine the corrected droop coefficient.

[0098] S45: Apply the corrected droop coefficient to the reactive voltage control loop of VGS, and form the output voltage command value of the grid-forming energy storage system island grid through PI control.

[0099] S46: Adaptively regulate the voltage according to the output voltage command value.

[0100] In practical applications, constructing a reactive voltage control loop specifically includes: based on the decoupled virtual power, separately build a reactive voltage control, introduce an adaptive droop coefficient in the reactive voltage control loop, dynamically adjust the reactive power output according to the operating state of the energy storage system, and optimize the voltage regulation.

[0101] The steps are as follows:

[0102] Dynamically collect the active power output of the energy storage system, subtract the active power collected from the apparent power of the energy storage system to calculate the reactive power capacity of the energy storage system, and combine the charge and discharge states of the energy storage system (charging τ > 0 or discharging τ < 0) to determine the upper and lower limits of the reactive power ( and ).

[0103] Dynamically adjust the droop coefficient (DQ) of the VSG reactive voltage control loop according to the reactive power capacity, and correct the voltage regulation equation.

[0104] The voltage regulation equation is as follows:

[0105]

[0106] U n is the rated voltage of the energy storage output, U ref , Q ref are the energy storage output voltage and reactive power command values respectively, and Q v is the reactive power output by the energy storage system after virtual power decoupling.

[0107] Apply the corrected droop coefficient to the reactive voltage control loop, and form the output voltage command value (U ref ) of the energy storage system through PI control to achieve adaptive voltage regulation.

[0108] Logic description: Through the adjustment of the adaptive droop coefficient of the reactive voltage control loop, give full play to the reactive power support potential of the energy storage system and optimize the voltage regulation ability of the island grid.

[0109] In practical applications, the construction of the VSG reactive voltage control loop specifically includes the following steps:

[0110] Determine the charge and discharge operating state of the energy storage system. According to the active power output of the energy storage system, determine the remaining reactive power capacity of the energy storage system. Combine the state of charge of the energy storage system to determine the maximum callable reactive power capacity under the two-way operation of the energy storage system. The reactive power capacity under the two-way charge and discharge operating state is related to the apparent power of the energy storage system and the active power generated or absorbed by the energy storage system at that time. The specific formula is as follows:

[0111]

[0112] In the formula, S ESS 2 is the apparent power of the energy storage system during operation, P ESS,t represents the active power output of the energy storage system, Q t max and Q t min are the upper and lower limits of the reactive power of the energy storage system respectively.

[0113] Determine the adaptive droop coefficient under the two-way charge and discharge operating state of the energy storage system according to the reactive power capacity. The specific formula is as follows:

[0114]

[0115] In the formula, ΔU max is the voltage fluctuation range at the grid connection point between the energy storage system and the island power grid, and it takes 0.1 pu when using per-unit values.

[0116] The adaptive droop coefficient D Q changes with the change of the reactive power capacity, improves the voltage reference value in the outer power loop control, and inputs the inner loop to realize the adaptive control of the inverter.

[0117] In an exemplary embodiment, after S4, it further includes:

[0118] S5: Dynamically adjust the parameters of the virtual impedance, the no-slip angular frequency adjustment link, and the droop coefficient according to the actual operating conditions of the island power grid of the grid-forming energy storage system, and determine the dynamic adjustment coefficient; the actual operating conditions include load changes and the state of the energy storage system.

[0119] S6: Apply the control loop composed of the dynamic adjustment coefficient to the VSG, and collect the voltage and frequency of the VSG in real time, evaluate the frequency stability and voltage stability of the VSG, and determine the evaluation result.

[0120] S7: Adjust the voltage regulation and frequency modulation strategy of the grid-forming energy storage system for the island power grid according to the evaluation results, and in extreme cases, activate the backup control strategy; the voltage regulation and frequency modulation strategy is the voltage regulation and frequency modulation method for the grid-forming energy storage system of the island power grid as described above; the backup control strategy is to disconnect the grid-forming energy storage system for the island power grid to form multiple local microgrids, and supply power by new energy, converting the global control into local disconnection control.

[0121] In practical applications, as Figure 4 shown, after S1 - S4, the construction of the grid-forming energy storage control loop is completed. During the entire control process, key parameters are continuously optimized to ensure the stability and performance of the system.

[0122] The steps are as follows:

[0123] According to the actual operating conditions of the island power grid (such as load changes, energy storage system status, etc.), dynamically adjust the parameters of the virtual impedance, the no-slip angular frequency adjustment link (K P and K i ) and the droop coefficient (D Q ).

[0124] Apply the control loop composed of dynamically adjusted coefficients to the power system, collect the voltage and frequency of the power system in real time, regularly evaluate the frequency and voltage stability of the system, set disturbances to obtain the stability evaluation of the power system frequency and voltage, and further optimize the frequency regulation and voltage regulation control strategy of the grid-forming energy storage island microgrid according to the evaluation results.

[0125] In extreme cases (such as sudden disconnection of the island power grid, energy storage system failure, etc.), activate the backup control strategy. This backup control strategy is to disconnect the grid to form multiple local microgrids, temporarily supply power by new energy, convert the global control into local disconnection control, cut off the loads that cannot be networked, and improve the power supply ratio of the loads as much as possible to ensure the reliability and stability of the system.

[0126] Logical explanation: By dynamically adjusting the key parameters of the active power frequency control loop and the reactive power voltage control loop, ensure that the system can maintain good performance and stability under different working conditions, and further improve the voltage regulation and frequency modulation capabilities of the island power grid.

[0127] The energy storage system is connected to the island power grid in a grid-forming control mode to provide dynamic frequency and voltage support. By adding virtual power, the active and reactive power decoupling is carried out for the power control loop of the VSG, and the frequency and voltage of the island microgrid are adjusted respectively; the active frequency control loop of the VSG adopts a self-recovery secondary frequency modulation control method that can achieve zero-error frequency modulation, and the reactive voltage control loop of the VSG adopts a voltage support control strategy with an adaptive droop coefficient. After decoupling the active power and reactive power, the present invention adds a zero-error adjustment module to the active control loop of the VSG, dynamically adjusts the reference value of the active power output, and then corrects the output frequency of the VSG. When the VSG operates in the island mode, zero-error frequency modulation can be achieved; when adjusting the voltage of the island power grid, the active power is not considered, and only the reactive power is adjusted. The reactive power capacity of the energy storage is introduced into the reactive voltage droop coefficient to give full play to the reactive power support potential of the energy storage system.

[0128] Based on the same inventive concept, the embodiment of the present application also provides a voltage regulation and frequency modulation device for a grid-forming energy storage system island power grid for implementing the voltage regulation and frequency modulation method of the grid-forming energy storage system island power grid involved above. The solution provided by this device to solve the problem is similar to the solution described in the above method. Therefore, the specific limitations in one or more embodiments of the voltage regulation and frequency modulation device for the grid-forming energy storage system island power grid provided below can refer to the limitations on the voltage regulation and frequency modulation method of the grid-forming energy storage system island power grid in the above text, and will not be repeated here.

[0129] In an exemplary embodiment, a voltage regulation and frequency modulation device for a grid-forming energy storage system island power grid is provided, including:

[0130] A virtual power formation module, configured to introduce a virtual impedance at the output end of the grid-forming energy storage system island power grid, and form virtual power by superimposing a virtual voltage drop.

[0131] A decoupling module, configured to input the virtual power into the VSG power control loop, perform decoupling control on the active power and reactive power, and determine the decoupled virtual power; the VSG power control loop includes an original active power control loop and an original reactive voltage control loop.

[0132] A frequency error adjustment module, configured to construct an active frequency control loop of the VSG based on the decoupled virtual power and perform zero-error frequency modulation on the frequency.

[0133] A voltage adjustment module, configured to construct a reactive voltage control loop of the VGS based on the decoupled virtual power, and introduce an adaptive droop coefficient into the reactive voltage control loop based on the reactive power capacity of the grid-forming energy storage system island power grid to adaptively adjust the voltage.

[0134] The present application realizes the decoupling of active and reactive power through virtual power decoupling and virtual impedance, which simplifies the control complexity.

[0135] Through the self - restoring secondary frequency regulation control method, the frequency is regulated without error.

[0136] Dynamically adjust the droop coefficient according to the operating state of the energy storage system to optimize voltage support.

[0137] In an exemplary embodiment, a computer device is provided. The computer device can be a server or a terminal. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O), and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non - volatile storage medium and an internal memory. The non - volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non - volatile storage medium. The database of the computer device is used to store the voltage regulation and frequency modulation data of the grid - forming energy storage system island power grid. The input / output interface of the computer device is used for the processor to exchange information with external devices. The communication interface of the computer device is used to communicate with external terminals through a network connection. When the computer program is executed by the processor, a voltage regulation and frequency modulation method for a grid - forming energy storage system island power grid is implemented.

[0138] In an exemplary embodiment, a computer device is provided, including a memory and a processor. A computer program is stored in the memory, and when the processor executes the computer program, the above - mentioned method is implemented.

[0139] In an exemplary embodiment, a computer - readable storage medium is provided, storing a computer program, and when the computer program is executed by the processor, the above - mentioned method is implemented.

[0140] In an exemplary embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by the processor, the above - mentioned method is implemented.

[0141] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memories. Non-volatile memories can include read-only memory (ROM), magnetic tapes, floppy disks, flash memories, optical memories, high-density embedded non-volatile memories, resistive random-access memories (ReRAM), magnetoresistive random-access memories (MRAM), ferroelectric random-access memories (FRAM), phase change memories (PCM), graphene memories, etc. Volatile memories can include random-access memory (RAM) or external cache memories, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random-access memory (SRAM) or dynamic random-access memory (DRAM), etc.

[0142] In this application, all actions of obtaining signals, information, or data are carried out on the premise of complying with the corresponding data protection regulations and policies of the country where the location is located and obtaining authorization from the owner of the corresponding device.

[0143] The databases involved in the embodiments provided in the present application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., without limitation. The processors involved in the embodiments provided in the present application can be general-purpose processors, central processors, graphics processors, digital signal processors, programmable logic devices, data processing logics based on quantum computing, etc., without limitation.

[0144] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0145] In this text, specific examples are used to elaborate on the principles and implementation manners of this application. The description of the above embodiments is only used to help understand the method and its core idea of this application. At the same time, for those of ordinary skill in the art, according to the idea of this application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to this application.

Claims

1. A voltage regulation and frequency modulation method for an island power grid of a network-forming energy storage system, characterized in that, The voltage regulation and frequency modulation method for the island power grid of the grid-forming energy storage system includes: Introduce a virtual impedance at the output end of the island power grid of the grid-forming energy storage system, and form a virtual power by superimposing a virtual voltage drop. Input the virtual power into the VSG power control loop to decouple and control the active power and reactive power, and determine the decoupled virtual power; the VSG power control loop includes the original active frequency control loop and the original reactive voltage control loop. Based on the decoupled virtual power, construct the active frequency control loop of the VSG to perform non-error regulation on the frequency. Based on the decoupled virtual power, construct the reactive voltage control loop of the VGS, and introduce an adaptive droop coefficient into the reactive voltage control loop based on the reactive power capacity of the island power grid of the grid-forming energy storage system to adaptively regulate the voltage.

2. The voltage regulation and frequency modulation method for the island power grid of the grid-forming energy storage system according to claim 1, characterized in that, Introduce a virtual impedance at the output end of the island power grid of the grid-forming energy storage system, and form a virtual power by superimposing a virtual voltage drop, specifically including: Determine the coupling coefficient of reactive power output to active power output and the coupling coefficient of active power output to reactive power output according to the virtual impedance. Determine the VSG output coupling coefficient according to the coupling coefficient of reactive power output to active power output and the coupling coefficient of active power output to reactive power output. When the VSG output coupling coefficient is the minimum value, calculate the virtual inductance value according to the resistance and reactance of the virtual impedance. Based on the virtual inductance value, determine the line impedance value after superimposing the virtual impedance according to the resistance and the reactance. Based on the Park transformation, obtain the VSG output current components, and calculate the virtual voltage drop according to the VSG output current components; the VSG output current components include the current d-axis component and the current q-axis component. Based on the line impedance value, superimpose the virtual voltage drop generated by the virtual impedance and the original VSG output voltage to form the VSG output virtual voltage value. Input the virtual voltage value and the VSG output current components into the power calculation module to determine the virtual power.

3. The voltage regulation and frequency modulation method for the island power grid of the network-forming energy storage system according to claim 2, characterized in that, Determine the VSG output coupling coefficient according to the coupling coefficient of reactive power output to active power output and the coupling coefficient of active power output to reactive power output, specifically including: Utilize Determine the VSG output coupling coefficient; where, K1 is the VSG output coupling coefficient; K p Is the coupling coefficient of reactive power output to active power output; K Q Is the coupling coefficient of active power output to reactive power output; R v Is the resistance; X v Is the reactance; δ is the power angle.

4. The voltage regulation and frequency modulation method for the island power grid of the network-forming energy storage system according to claim 1, characterized in that, Based on the decoupled virtual power, construct the active frequency control loop of the VSG to perform non-error regulation on the frequency, specifically including: Real-time collect the frequency fluctuations on the load side of the island power grid of the grid-forming energy storage system, and calculate the active power regulation deviation through the active control loop based on the decoupled virtual power. Superimpose the active power regulation deviation on the active power output command value of the VSG, and dynamically adjust the active power output of the island power grid of the grid-forming energy storage system through the VSG synchronous generator mechanical rotor equation. Based on the active power output, construct the active frequency control loop of the VSG, and add a non-error angular frequency regulation link to the active frequency control loop of the VSG to correct the active power command value and perform non-error regulation on the frequency.

5. The voltage regulation and frequency modulation method for the island power grid of the network-forming energy storage system according to claim 1, characterized in that, Based on the decoupled virtual power, construct the reactive voltage control loop of the VGS, and introduce an adaptive droop coefficient into the reactive voltage control loop based on the reactive power capacity of the island power grid of the grid-forming energy storage system to adaptively regulate the voltage, specifically including: Dynamically collect the active power output of the grid-forming energy storage system's island power grid, and based on the decoupled virtual power, calculate the reactive power capacity of the grid-forming energy storage system's island power grid according to the apparent power and the active power output of the grid-forming energy storage system's island power grid; Determine the upper and lower limits of reactive power according to the reactive power capacity and in combination with the charge and discharge state of the grid-forming energy storage system's island power grid; Based on the upper and lower limits of reactive power, construct a reactive voltage control loop for the VGS; Dynamically adjust the droop coefficient of the reactive voltage control loop of the VGS according to the reactive power capacity, correct the voltage regulation equation, and determine the corrected droop coefficient; Apply the corrected droop coefficient to the reactive voltage control loop of the VGS, and form the output voltage command value of the grid-forming energy storage system's island power grid through PI control; Adaptive voltage regulation is performed according to the output voltage command value.

6. The voltage regulation and frequency modulation method for the island power grid of the network-forming energy storage system according to claim 1, characterized in that Based on the decoupled virtual power, construct a reactive voltage control loop for the VGS, and introduce an adaptive droop coefficient into the reactive voltage control loop based on the reactive power capacity of the grid-forming energy storage system's island power grid to adaptively regulate the voltage. After that, it further includes: Dynamically adjust the parameters of the virtual impedance, the zero-difference angular frequency adjustment link, and the droop coefficient according to the actual operating conditions of the grid-forming energy storage system's island power grid, and determine the dynamic adjustment coefficient; the actual operating conditions include load changes and the state of the energy storage system; Apply the control loop composed of the dynamic adjustment coefficients to the VSG, and collect the voltage and frequency of the VSG in real time, evaluate the frequency stability and voltage stability of the VSG, and determine the evaluation result; Adjust the voltage regulation and frequency modulation strategy of the grid-forming energy storage system's island power grid according to the evaluation result, and in extreme cases, activate the standby control strategy; the voltage regulation and frequency modulation strategy is the voltage regulation and frequency modulation method of the grid-forming energy storage system's island power grid described in any one of claims 1-4; the standby control strategy is to disconnect the grid-forming energy storage system's island power grid to form multiple local microgrids, and supply power by new energy, converting the global control into local disconnection control.

7. A voltage regulation and frequency modulation device for an island power grid of a network-forming energy storage system, characterized in that, The voltage regulation and frequency modulation device of the grid-forming energy storage system's island power grid includes: A virtual power formation module, which is used to introduce a virtual impedance at the output end of the grid-forming energy storage system's island power grid and form virtual power by superimposing a virtual voltage drop; A decoupling module, which is used to input the virtual power into the VSG power control loop, perform decoupling control on the active power and reactive power, and determine the decoupled virtual power; the VSG power control loop includes an original active power control loop and an original reactive voltage control loop; A frequency error adjustment module, which is used to construct an active frequency control loop for the VSG based on the decoupled virtual power and perform zero-difference adjustment on the frequency; A voltage adjustment module, which is used to construct a reactive voltage control loop for the VGS based on the decoupled virtual power, and introduce an adaptive droop coefficient into the reactive voltage control loop based on the reactive power capacity of the grid-forming energy storage system's island power grid to adaptively regulate the voltage.

8. A computer device, comprising: A memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that the processor executes the computer program to implement the voltage regulation and frequency modulation method for the grid-forming energy storage system island grid according to any one of claims 1-6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the voltage regulation and frequency modulation method for the grid-forming energy storage system island grid according to any one of claims 1-6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the voltage regulation and frequency modulation method for the grid-forming energy storage system island grid according to any one of claims 1-6.

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