Method for grid support by reshaping controller using grid-connected energy storage converter

Abstract

The present invention discloses a method for supporting a power grid by using a reshaping controller of a grid-type energy storage converter, comprising: constructing a voltage reshaping controller model of the grid-type energy storage converter, and constructing a voltage support capability criterion of the voltage reshaping controller model; constructing a frequency reshaping controller model of the grid-type energy storage converter, and constructing a frequency support capability criterion of the frequency reshaping controller model, wherein the frequency reshaping controller model includes virtual frequency modulation control and virtual inertia and damping control; constructing a transient power angle reshaping controller of the grid-type energy storage converter, and constructing a power angle stability control start-up criterion of the transient power angle reshaping controller model; constructing a reshaping controller model of the grid-type energy storage converter according to the voltage reshaping controller model, the frequency reshaping controller model and the transient power angle reshaping controller model; supporting the power grid according to the voltage support capability criterion, the frequency support capability criterion and the power angle stability control start-up criterion of the reshaping controller model.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid support, and more specifically, to a method for power grid support using a grid-forming energy storage converter remodeling controller. Background Art

[0002] The penetration rate of renewable energy such as wind and solar energy in modern power systems continues to increase, which brings a lot of challenges to their stable and safe operation. Based on this background, energy storage technology has emerged. Among them, energy storage converter control is the key point, and its main control methods include grid-following control and grid-building control. According to recent studies, grid-building control shows better grid support characteristics than grid-following control, such as stable operation under low short-circuit ratio conditions, providing frequency support and voltage support, etc. Therefore, the application prospects of grid-building control energy storage converters are relatively broad. At present, there are few reports on the comprehensive optimization strategies of energy storage converters in terms of transient voltage frequency of the grid and transient power angle of the system. Therefore, how to construct a grid-building energy storage converter to access the grid and provide comprehensive support for it has become a technical problem that needs to be solved urgently. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a method for supporting a power grid by reshaping a controller using a grid-forming energy storage converter.

[0004] According to one aspect of the present invention, there is provided a method for grid support using a grid-connected energy storage converter remodeling controller, comprising:

[0005] Construct a voltage reshaping controller model for a grid-connected energy storage converter, and construct a voltage support capability criterion for the voltage reshaping controller model;

[0006] Construct a frequency reshaping controller model of a grid-connected energy storage converter and construct a frequency support capability criterion for the frequency reshaping controller model, wherein the frequency reshaping controller model includes virtual frequency modulation control and virtual inertia and damping control;

[0007] Construct a transient power angle reshaping controller for grid-connected energy storage converters, and construct the power angle stability control start-up criterion of the transient power angle reshaping controller model;

[0008] According to the voltage reshaping controller model, the frequency reshaping controller model and the transient power angle reshaping controller model, a reshaping controller model of the grid-connected energy storage converter is constructed;

[0009] The grid-forming energy storage converter is connected to the power grid, and the power grid is supported according to the voltage support capability criterion, frequency support capability criterion and power angle stability control start-up criterion of the reshaped controller model.

[0010] Optionally, the voltage reshaping controller model is:

[0011]

[0012] In the formula, E is the potential amplitude in the converter, K is the regulator gain, K v Select the factor for proportional-integral, T 1 and T 2 are the first voltage regulator time constant and the second voltage regulator time constant, U t * is the grid connection point voltage reference value, U t Grid connection voltage, is the time constant of the virtual excitation winding, s is the Laplace operator.

[0013] Optionally, it also includes: using a particle swarm optimization algorithm to adjust the parameters of the voltage reshaping controller model , T 1 and T 2Perform adjustment.

[0014] Optionally, a particle swarm optimization algorithm is used to optimize the parameters of the voltage reshaping controller model , T 1 and T 2 Perform tuning, including:

[0015] Step 1: Generate a certain number of particles and initialize the particle dimension, particle position and particle velocity;

[0016] Step 2: Assign particles to time constants , T 1 and T 2. Run the simulation model, calculate the objective function, and generate the objective function value;

[0017] Step 3: Compare the objective function values ​​in the iteration process and update the local optimal value of the particle and the global optimal solution;

[0018] Step 4: Update the particle speed and position according to the local optimal value and the global optimal solution of the particle, and limit the particle position and speed within the preset range;

[0019] Step 5: Determine whether the maximum number of iterations has been reached or the convergence condition has been met. If so, terminate the algorithm and output the optimized , T 1 and T 2, otherwise return to step 2 for iterative calculation, where the objective function is:

[0020]

[0021] In the formula, J is the equivalent inertia time constant of the grid-type energy storage converter, T is the time constant, t 0 is the time when the fault occurs.

[0022] Optionally, the voltage support capability criterion is:

[0023]

[0024] In the formula, U t is the grid connection point voltage; is the potential phase in the converter; Q is the reactive power; x c To connect the grid-type energy storage converter to the grid-connected point.

[0025] Optionally, the frequency reshaping controller model is:

[0026]

[0027] In the formula, J is the equivalent inertia time constant of the grid-type energy storage converter, K L is the equivalent damping coefficient of the grid-type energy storage converter, K VD is the transient damping control coefficient, is the potential phase in the converter, P ref is the power reference value, P is the output electromagnetic power, ω is the angular frequency of the energy storage converter, ω 0 is the angular frequency reference value, t For time.

[0028] Optionally, the frequency support capability criterion is:

[0029]

[0030]

[0031] In the formula, k d is the damping proportional coefficient, k j is the inertia proportional coefficient, K W is the grid-type droop control coefficient, K n The proportion of new energy units participating in frequency regulation, J 1 is the inertia coefficient of virtual synchronous machine control,M d and M j They are K L and J The frequency change rate of the parameter starts the dead zone, is the frequency change, d f / d t is the frequency change rate.

[0032] Optionally, the transient power angle reshaping control model is:

[0033]

[0034] In the formula, is the power dynamic compensation amount, k is the compensation coefficient, U g is the initial amplitude of the grid voltage, U g1 is the amplitude when the power grid drops.

[0035] Optionally, the power angle stabilization control start criterion is:

[0036] Step 1: Collect the current angular velocity of the grid-type energy storage converter ω ;

[0037] Step 2: Determine the change in angular velocity Whether it exceeds the threshold ω t If it does not exceed, determine whether the fault is cleared. If the grid fault is cleared, end the algorithm. If the grid fault is not cleared, return to step 1.

[0038] Step 3: If the angular velocity change exceeds the threshold, determine whether the angular velocity change is positive or negative. If the angular velocity change is positive, execute , otherwise execute , after the execution is completed, return to step 1, where P in is the compensation amount of the power reference value.

[0039] Optionally, supporting the power grid according to the voltage support capability criterion, the frequency support capability criterion and the power angle stability control start-up criterion of the remodeling controller model includes:

[0040] Output the potential phase in the converter according to the power angle stability control start-up criterion and the frequency support capability criterion;

[0041] The potential inside the output converter is determined based on the voltage support capability;

[0042] The grid is supported according to the potential phase and the potential within the converter.

[0043] According to another aspect of the present invention, there is provided a device for grid support using a grid-connected energy storage converter remodeling controller, comprising:

[0044] The first construction module is used to construct a voltage reshaping controller model of a grid-connected energy storage converter and to construct a voltage support capability criterion of the voltage reshaping controller model;

[0045] The second construction module is used to construct a frequency reshaping controller model of the grid-type energy storage converter and to construct a frequency support capability criterion of the frequency reshaping controller model, wherein the frequency reshaping controller model includes virtual frequency modulation control and virtual inertia and damping control;

[0046] The third building block is used to build a transient power angle reshaping controller for a grid-connected energy storage converter and to build a power angle stability control start criterion for the transient power angle reshaping controller model;

[0047] The fourth construction module is used to construct a reshaping controller model of a grid-connected energy storage converter according to the voltage reshaping controller model, the frequency reshaping controller model and the transient power angle reshaping controller model;

[0048] The support module is used to connect the grid-building energy storage converter to the power grid and support the power grid according to the voltage support capability criterion, frequency support capability criterion and power angle stability control start-up criterion of the reshaped controller model.

[0049] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the storage medium stores a computer program, and the computer program is used to execute the method described in any one of the above aspects of the present invention.

[0050] According to another aspect of the present invention, an electronic device is provided, comprising: a processor; a memory for storing instructions executable by the processor; the processor is configured to read the executable instructions from the memory and execute the instructions to implement the method described in any one of the above aspects of the present invention.

[0051] Therefore, the present application constructs a voltage reshaping controller model, a frequency reshaping controller module and a transient power angle reshaping controller model of a grid-type energy storage converter, and constructs voltage support capability criteria, frequency support capability criteria and transient power angle stability control start criteria to support the power grid. By realizing the reshaping of the voltage, frequency and transient power angle of the energy storage converter, the voltage and frequency strength of the power grid system can be improved, and the transient power angle stability can also be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0053] Figure 1 It is a flow chart of a method for performing grid support by using a grid-type energy storage converter remodeling controller provided by an exemplary embodiment of the present invention;

[0054] Figure 2 It is a schematic diagram of a grid-type energy storage converter model based on virtual excitation provided by an exemplary embodiment of the present invention;

[0055] Figure 3 It is a simplified model schematic diagram of a grid-type energy storage converter provided by an exemplary embodiment of the present invention;

[0056] Figure 4 is a parameter optimization flow chart based on a particle swarm algorithm provided by an exemplary embodiment of the present invention;

[0057] Figure 5 is a schematic diagram of a transient power angle characteristic curve provided by an exemplary embodiment of the present invention;

[0058] Figure 6 is a flow chart of power angle reshaping control implementation provided by an exemplary embodiment of the present invention;

[0059] Figure 7 This is a simulation diagram comparing the voltage support capability of a grid-type energy storage converter before and after the voltage reshaping controller model is started according to an exemplary embodiment of the present invention;

[0060] Figure 8 This is a simulation diagram comparing the frequency support capability of a grid-type energy storage converter before and after the frequency reshaping controller model is started, provided by an exemplary embodiment of the present invention;

[0061] Fig. 9 It is a waveform diagram of the active power output of a grid-type energy storage converter before starting a transient power angle reshaping controller model provided by an exemplary embodiment of the present invention;

[0062] Fig.10 It is a waveform diagram of the active power output of the grid-type energy storage converter after the transient power angle reshaping controller model provided by an exemplary embodiment of the present invention is started;

[0063] Fig.11 It is a structural schematic diagram of a device for grid support using a grid-type energy storage converter remodeling controller provided by an exemplary embodiment of the present invention;

[0064] Fig.12 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0065] Below, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and it should be understood that the present invention is not limited to the exemplary embodiments described here.

[0066] It should be noted that the relative arrangement of components and steps, the numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

[0067] Those skilled in the art can understand that the terms "first" and "second" in the embodiments of the present invention are only used to distinguish different steps, devices or modules, etc., and neither represent any specific technical meaning nor indicate the necessary logical order between them.

[0068] It should also be understood that, in the embodiments of the present invention, “plurality” may refer to two or more than two, and “at least one” may refer to one, two or more than two.

[0069] It should also be understood that any component, data or structure mentioned in the embodiments of the present invention can generally be understood as one or more, unless explicitly limited or otherwise indicated in the context.

[0070] In addition, the term "and / or" in the present invention is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects before and after are in an "or" relationship.

[0071] It should also be understood that the description of the various embodiments of the present invention focuses on the differences between the various embodiments, and the same or similar aspects thereof can be referenced to each other, and for the sake of brevity, they will not be described one by one.

[0072] At the same time, it should be understood that for the convenience of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship.

[0073] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0074] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0075] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0076] Embodiments of the present invention can be applied to electronic devices such as terminal devices, computer systems, servers, etc., which can operate with many other general or special computing system environments or configurations. Examples of well-known terminal devices, computing systems, environments and / or configurations suitable for use with electronic devices such as terminal devices, computer systems, servers, etc. include, but are not limited to: personal computer systems, server computer systems, thin clients, thick clients, handheld or laptop devices, microprocessor-based systems, set-top boxes, programmable consumer electronics, network personal computers, small computer systems, large computer systems, and distributed cloud computing technology environments including any of the above systems, etc.

[0077] Electronic devices such as terminal devices, computer systems, servers, etc. can be described in the general context of computer system executable instructions (such as program modules) executed by computer systems. Generally, program modules can include routines, programs, object programs, components, logic, data structures, etc., which perform specific tasks or implement specific abstract data types. Computer systems / servers can be implemented in a distributed cloud computing environment, where tasks are performed by remote processing devices linked through a communication network. In a distributed cloud computing environment, program modules can be located on local or remote computing system storage media including storage devices.

[0078] Exemplary Methods

[0079] Figure 1 1 is a flow chart of a method for using a grid-type energy storage converter to reshape a controller for grid support provided by an exemplary embodiment of the present invention. This embodiment can be applied to electronic devices, such as Figure 1 As shown, the method 100 for grid support using a grid-connected energy storage converter remodeling controller includes the following steps:

[0080] Step 101, constructing a voltage reshaping controller model of a grid-connected energy storage converter, and constructing a voltage support capability criterion of the voltage reshaping controller model;

[0081] Step 102, constructing a frequency reshaping controller model of a grid-connected energy storage converter, and constructing a frequency support capability criterion of the frequency reshaping controller model, wherein the frequency reshaping controller model includes virtual frequency modulation control and virtual inertia and damping control;

[0082] Step 103, constructing a transient power angle reshaping controller for a grid-connected energy storage converter, and constructing a power angle stability control start criterion for a transient power angle reshaping controller model;

[0083] Step 104, constructing a reshaping controller model of a grid-connected energy storage converter according to the voltage reshaping controller model, the frequency reshaping controller model, and the transient power angle reshaping controller model;

[0084] Step 105, connecting the grid-forming energy storage converter to the grid, and supporting the grid according to the voltage support capability criterion, frequency support capability criterion and power angle stability control start-up criterion of the remodeling controller model.

[0085] Specifically, the present invention proposes a method for grid support using a grid-connected energy storage inverter reshaping controller. The grid-connected energy storage inverter reshapes the controller, including voltage reshaping, frequency reshaping, and transient power angle reshaping, thereby comprehensively improving the voltage and frequency strength of the grid-connected energy storage inverter after connection, and also improving the transient power angle stability of the system.

[0086] In one embodiment, the voltage reshaping controller model of the grid-connected energy storage converter is as follows: Figure 2 As shown, the voltage reshaping controller of the energy storage converter is first constructed. During the transient period of the grid voltage, the dynamic characteristics of the grid-type energy storage converter are mainly determined by the inverter dynamics. Figure 2 The model structure of grid-connected energy storage converter using virtual excitation control is given, which mainly includes:

[0087] 1) Synchronous control module, using virtual synchronous machine control, is used to achieve synchronous grid connection of converters, including virtual inertia and damping control, virtual frequency modulation control and transient power angle stability control, generating potential phase in converters , the specific expression is:

[0088] (1)

[0089] In the formula, J 1 is the inertia coefficient of virtual synchronous machine control, D p is the virtual synchronous machine control damping coefficient, P ref is the power reference value.

[0090] 2) Internal potential control, used to generate the internal potential amplitude of the converter E , using virtual excitation control, the specific expression is:

[0091] (2)

[0092] In the formula, E is the potential amplitude in the converter, K is the regulator gain, K v Select the factor for proportional-integral, T 1 and T2 are the first voltage regulator time constant and the second voltage regulator time constant, U t * is the grid connection point voltage reference value, U t Grid connection voltage, is the time constant of the virtual excitation winding, s is the Laplace operator. The dynamic characteristics of the grid-type energy storage converter described by equations (1) and (2) can be equivalent to a voltage source in series with an impedance, as follows: Figure 3 shown.

[0093] Figure 3 The comments for the relevant variables are as follows:

[0094] 1) is the potential vector inside the grid-type energy storage converter based on virtual excitation control, , E is the internal potential amplitude of the grid-type energy storage converter, The internal potential phase of the grid-type energy storage converter is output by the synchronous control module.

[0095] 2) is the grid-connected point voltage vector of the grid-connected energy storage converter, , is the grid connection point voltage, is the voltage phase at the grid connection point.

[0096] 3) x c The reactance connected to the grid-type energy storage converter and the grid connection point includes the energy storage converter bridge arm reactance, filter reactance, transformer equivalent reactance, etc.

[0097] Figure 3 middle is the output current vector of the grid-type energy storage converter, and the grid-connected point voltage is used as the reference voltage ( middle ), the output current expression of the grid-type energy storage converter is obtained as:

[0098] (3)

[0099] In the formula, the first term on the right side of the equation is the active current, and the second term is the reactive current. ，j Is an imaginary unit.

[0100] Based on formula (3), the analytical expression of the dynamic power injected into the grid connection point by the grid-connected energy storage converter during the transient state of the grid voltage can be obtained as follows:

[0101] (4)

[0102] In the formula, U tis the grid voltage, P is the output electromagnetic power, I* for I The conjugate of , solve for reactive power Q right U t The derivative of is, that is, the voltage support capability criterion is:

[0103] (5)

[0104] In the formula, E Determined by the virtual excitation control module, the potential amplitude in the converter supporting the power grid can be adjusted by adjusting the control parameters of the virtual excitation control module E Output characteristics.

[0105] The voltage support capability of the grid-connected energy storage converter during transient conditions can be evaluated by formula (5).

[0106] When the fault causes the actual voltage signal of the system U t When the power is reduced, the grid-type energy storage converter should output reactive power Q To do this, it is necessary to meet , and the absolute value It is large enough to output as much reactive power as possible per unit time, and the voltage support capacity is also stronger.

[0107] Combining equation (2) and equation (5) can be optimized from the following two aspects:

[0108] 1) Optimization method based on electrical parameters:

[0109] x c The smaller, The larger the absolute value, the faster the reactive power response of the grid-connected energy storage converter during the transient state of the grid voltage. It can respond to as much dynamic reactive power output as possible in unit time and provide rapid support to the grid. x c In order to construct the grid-type energy storage converter and connect the reactance to the grid point, including the converter bridge arm reactance, filter reactance, and transformer equivalent reactance, it is necessary to consider factors such as the reactance volume, structure, and cost for comprehensive design.

[0110] 2) Optimization method based on control parameters:

[0111] After the power grid transient, the unit time E The larger the amplitude, The larger the absolute value, the faster the reactive power response of the grid-connected energy storage converter during the transient state of the grid voltage, and the stronger the voltage support energy. According to formula (2), the time constant of the excitation winding can be adjusted ,T 1 and T 2. The bandwidth of the virtual excitation control module is increased, the response is faster, and the E The larger the amplitude, the more optimized the voltage support capability of the grid-connected energy storage converter can be achieved during the transient period.

[0112] Since the grid-type energy storage converter model is nonlinear, it is difficult to use analytical methods to calculate the time constant , T 1 and T 2. Parameter setting. The particle swarm optimization algorithm has the advantages of being easy to implement and fast in convergence, so the present invention uses the particle swarm optimization algorithm to optimize the above parameters. The specific optimization steps are as follows:

[0113] (1) A certain number of particles are generated and the particle dimensions, particle positions, and particle velocities are initialized.

[0114] (2) Assign particles to time constants , T 1 and T 2, and run the simulation model to calculate the objective function.

[0115] (3) Compare the objective function values ​​during the iteration process and update the local optimal value of the particle and the global optimal solution.

[0116] (4) Update the particle velocity and position, and limit the particle position and velocity within the limit range.

[0117] (5) Determine whether the algorithm has reached the maximum number of iterations or meets the convergence condition. If so, terminate the algorithm and output the optimized time constant value. Otherwise, return to step (2).

[0118] According to the above steps, the parameter optimization flow chart based on particle swarm algorithm can be obtained, as shown in Figure 4 shown.

[0119] According to the previous analysis, the faster the voltage response of the grid-type energy storage converter is, the more reactive power is output per unit time, which is more beneficial to the transient process of the system. Therefore, the present invention adopts an objective function based on the absolute value of the voltage deviation multiplied by the time integral, and the expression is as follows:

[0120]

[0121] In the formula, T is a time constant, which is usually larger to ensure that the system can enter a stable state. t 0 is the time when the fault occurs.

[0122] In one embodiment, the frequency reshaping controller model of the grid-connected energy storage converter is constructed as follows:

[0123] The transfer function is established for the system frequency response model obtained after aggregation, considering the frequency modulation of new energy and the role of inertia support, assuming that the disturbance is a step function, and writing the frequency response expression:

[0124] (6)

[0125] Where: , , , , . R , T R , F H They are the governor speed gain, reheater time constant, and high-pressure cylinder power ratio of the conventional unit. is the system disturbance power, H sys is the equivalent inertia time constant, H sys =( K ns * H n + K ms * H m ) / ( K ns + K ms ), D sys is the load frequency regulation characteristic, K ms is the proportion of installed capacity of conventional units, K ns is the proportion of installed capacity of new energy generators, K W is the grid-type droop control coefficient, K VD is the transient damping control coefficient, K n The proportion of new energy units participating in frequency regulation, H m is the synchronous machine inertia, H n It is the virtual inertia of new energy;

[0126] Derivative equation (6) and set its derivative value to 0 to obtain the time when the maximum frequency deviation occurs:

[0127] (7)

[0128] Substituting equation (7) into the time domain expression (6), we can obtain the maximum frequency deviation:

[0129] (8)

[0130] Given the maximum frequency deviation that the system can withstand, the maximum disturbance power that the system can withstand is obtained by inverse solution, which is used as the maximum strength when the system needs the grid-type to provide frequency support. When the grid-type energy storage converter does not participate in primary frequency modulation and inertia control, the proportion of the system synchronous machine is K m The maximum disturbance power that the time-inverse solution system can withstand is:

[0131] (9)

[0132] Define the frequency intensity coefficient:

[0133] (10)

[0134] When the disturbance , that is, the strength coefficient η <1, the grid-connected energy storage converter needs to be started for frequency support, otherwise the frequency is considered stable.

[0135] A meshed frequency reshaping controller including virtual frequency modulation control, virtual inertia control and damping control is proposed. Figure 2 shown.

[0136] Simulate the governor characteristics of the synchronous generator prime mover and simplify the consideration of its P - f Characteristics. The converter detects the actual frequency of the power grid and compares it with the reference frequency. After passing through the dead zone control module, if the frequency deviation exceeds the set dead zone width, the actual deviation is output; otherwise, the output is 0. The output frequency deviation multiplied by the droop coefficient can be used to obtain the power reference value addition. .

[0137] (11)

[0138] In the formula, f * Set the reference value for the frequency, f deadzone is the speed regulator control dead zone, f is the measured frequency value.

[0139] The synchronous generator rotor motion equation is simulated, and inertia and damping links are introduced in the control to enhance the flexible grid-connected characteristics of the converter. The sum of the additional reference power obtained in the virtual frequency modulation control link and the active reference command is used as the virtual mechanical power of the converter, and the actual output active power of the converter is used as the virtual electromagnetic power. The difference between the two is passed through the inertia and damping control link to obtain the virtual speed of the energy storage converter, and the virtual internal potential phase angle can be obtained by integration.

[0140] To enhance the virtual damping control capability, the transient damping control coefficient consists of two parts in parallel.

[0141] (12)

[0142] In the formula, T w , T 3. T 4 is the damping regulator time constant, K D is the transient damping control proportional coefficient.

[0143] According to the formula , the required grid droop coefficient is:

[0144] (13)

[0145] When the frequency reaches the lowest point, in order to reduce the maximum frequency deviation, the inertia should be increased as much as possible and the damping coefficient should be kept unchanged; after reaching the maximum deviation, in the process of recovering to the steady-state frequency, the damping coefficient should be increased as much as possible and the inertia should be kept unchanged. Therefore, an adaptive inertia and droop parameter optimization control is proposed.

[0146] The inertia and damping parameters are optimized and controlled at different stages:

[0147] (14)

[0148] (15)

[0149] In the formula, J is the equivalent inertia time constant of the energy storage converter, K L is the equivalent damping coefficient of the energy storage converter, k d is the damping proportional coefficient, k j is the inertia proportional coefficient.

[0150] To prevent oscillation or steady-state deviation from causing frequent adaptive parameter control actions, set J and K LThe frequency change rate of the parameters start dead zone respectively: M d and M j .

[0151] The input and output equations of the frequency reshaping controller model are: , used to output the internal potential phase of the grid-type energy storage converter.

[0152] In one embodiment, the transient power angle reshaping controller model of the grid-connected energy storage converter is constructed as follows:

[0153] When a grid fault occurs and the grid voltage drops, the energy storage converter outputs electromagnetic power P which decreases. At this time, the active power reference value P ref Greater than electromagnetic power P , the system angular frequency increases and runs faster, which will cause the virtual power angle of the energy storage converter to increase. After the fault is cleared, the output electromagnetic power of the energy storage converter P Will be greater than the active power P ref , the system decelerates. The complete operation process is as follows Figure 5 As shown, the system power angle operation trajectory is abcd. At the operating point d, if the acceleration area S1 is larger than the deceleration area S2, the entire system will lose stability. If the acceleration area S1 is smaller than the deceleration area S2, the system will return to the initial state and operate normally.

[0154] Based on the above analysis, it is necessary to construct a transient power angle reshaping controller for adaptive regulation. P ref To enhance the transient stability of the system. U g Fall to U g1 ,and U g1 <0.8 U g , it is considered that the power grid fails, and the power reference value is determined at this time P ref Compensation The size of is as shown in formula (16):

[0155] (16)

[0156] In the formula, is the power dynamic compensation amount, k is the compensation coefficient.

[0157] Under grid fault conditions, the transient power angle is triggered to reshape the stability controller model. The specific implementation flow chart is as follows: Figure 6 As shown, Figure 6 Medium, threshold value ω t The purpose of this setting is to avoid the impact of repeated actions of the strategy and sampling errors during the fault recovery process. P in is the input power of the transient power angle stabilizer. , where m is an integer, T s is the sampling period.

[0158] The specific implementation steps are as follows:

[0159] 1) Collect the current angular velocity of the energy storage converter ω ;

[0160] 2) Determine the change in angular velocity Whether it exceeds the threshold ω t If it does not exceed, determine whether the fault is cleared. If the fault is cleared, end the algorithm. If the fault is not cleared, return to the first step;

[0161] 3) If the angular velocity change exceeds the threshold, determine whether the change is positive or negative. If the change is positive, execute , otherwise execute . After execution, return to the first step.

[0162] In addition, the present invention proposes a method for grid support using a grid-type energy storage converter reshaping controller. It can achieve the reshaping of the voltage, frequency and transient power angle of the grid-type energy storage converter, improve the voltage and frequency strength of the system, and also improve the transient power angle stability. In order to verify the effectiveness of the energy storage converter reshaping controller, relevant simulation experiments were carried out. The system structure is as follows Figure 2 As shown, Figure 7 This is a simulation diagram comparing the voltage support capability of the grid-type energy storage converter before and after the voltage reshaping controller model is started. Figure 7 It can be seen that after the reshaping control is started, the rate at which the energy storage converter outputs reactive power is significantly increased, and the voltage recovery rate is also increased accordingly. Therefore, during the transient process, the voltage support strength of the energy storage converter becomes greater. Figure 8 This is a simulation diagram comparing the frequency support capability of the grid-type energy storage converter before and after the frequency reshaping controller model is started. Figure 8 It can be seen that the grid-type energy storage converter can effectively reduce the maximum frequency deviation and the steady-state frequency deviation after participating in the frequency modulation. Therefore, in the dynamic process of the system, the frequency stability strength of the system is increased. Fig. 9 and Fig.10The following are the waveforms of the active power output of the grid-connected energy storage converter before and after the transient power angle reshaping controller model is started. By comparing the two figures, it can be seen that after adding the stability controller, the grid-connected energy storage converter can operate normally under power grid faults. The above simulation verifies the effectiveness of the grid-connected energy storage converter reshaping controller.

[0163] Therefore, the present application constructs a voltage reshaping controller model, a frequency reshaping controller module and a transient power angle reshaping controller model of a grid-type energy storage converter, and constructs voltage support capability criteria, frequency support capability criteria and transient power angle stability control start criteria to support the power grid. By realizing the reshaping of the voltage, frequency and transient power angle of the energy storage converter, the voltage and frequency strength of the power grid system can be improved, and the transient power angle stability can also be improved.

[0164] Exemplary Devices

[0165] Fig.11 FIG. 1 is a schematic diagram of a device for grid support using a grid-type energy storage converter remodeling controller provided by an exemplary embodiment of the present invention. Fig.11 As shown, the apparatus 1100 includes:

[0166] The first construction module 1111 is used to construct a voltage reshaping controller model of a grid-connected energy storage converter and to construct a voltage support capability criterion of the voltage reshaping controller model;

[0167] The second construction module 1120 is used to construct a frequency reshaping controller model of the grid-type energy storage converter and to construct a frequency support capability criterion of the frequency reshaping controller model, wherein the frequency reshaping controller model includes virtual frequency modulation control and virtual inertia and damping control;

[0168] The third construction module 1130 is used to construct a transient power angle reshaping controller for a grid-connected energy storage converter, and to construct a power angle stability control start criterion for a transient power angle reshaping controller model;

[0169] A fourth construction module 1140 is used to construct a reshaping controller model of a grid-connected energy storage converter according to the voltage reshaping controller model, the frequency reshaping controller model and the transient power angle reshaping controller model;

[0170] The support module 1150 is used to connect the grid-building energy storage converter to the grid and support the grid according to the voltage support capability criterion, frequency support capability criterion and power angle stability control start-up criterion of the remodeling controller model.

[0171] Optionally, the voltage reshaping controller model is:

[0172]

[0173] In the formula, E is the potential amplitude in the converter, K is the regulator gain, K v Select the factor for proportional-integral, T 1 and T 2 are the first voltage regulator time constant and the second voltage regulator time constant, U t * is the grid connection point voltage reference value, U t Grid connection voltage, is the time constant of the virtual excitation winding, s is the Laplace operator.

[0174] Optionally, the device 1100 further includes: a setting module for adjusting the parameters of the voltage reshaping controller model using a particle swarm optimization algorithm. , T 1 and T 2Perform adjustment.

[0175] Optionally, a tuning module comprising:

[0176] Step 1: Generate a certain number of particles and initialize the particle dimension, particle position and particle velocity;

[0177] Step 2: Assign particles to time constants , T 1 and T 2. Run the simulation model, calculate the objective function, and generate the objective function value;

[0178] Step 3: Compare the objective function values ​​in the iteration process and update the local optimal value of the particle and the global optimal solution;

[0179] Step 4: Update the particle speed and position according to the local optimal value and the global optimal solution of the particle, and limit the particle position and speed within the preset range;

[0180] Step 5: Determine whether the maximum number of iterations has been reached or the convergence condition has been met. If so, terminate the algorithm and output the optimized , T 1 and T 2, otherwise return to step 2 for iterative calculation, where the objective function is:

[0181]

[0182] In the formula, J is the equivalent inertia time constant of the grid-type energy storage converter, T is the time constant, t 0 is the time when the fault occurs.

[0183] Optionally, the voltage support capability criterion is:

[0184]

[0185] In the formula, U t is the grid connection point voltage; is the potential phase in the converter; Q is the reactive power; x c To connect the grid-type energy storage converter to the grid-connected point.

[0186] Optionally, the frequency reshaping controller model is:

[0187]

[0188] In the formula, J is the equivalent inertia time constant of the grid-type energy storage converter, K L is the equivalent damping coefficient of the grid-type energy storage converter, K VD is the transient damping control coefficient, is the potential phase in the converter, P ref is the power reference value, P is the output electromagnetic power, ω is the angular frequency of the energy storage converter, ω 0 is the angular frequency reference value, t For time.

[0189] Optionally, the frequency support capability criterion is:

[0190]

[0191]

[0192] In the formula, k d is the damping proportional coefficient, k j is the inertia proportional coefficient, K W is the grid-type droop control coefficient, K n The proportion of new energy units participating in frequency regulation, J 1 is the inertia coefficient of virtual synchronous machine control, M d and M j They are K L and J The frequency change rate of the parameter starts the dead zone, is the frequency change, d f / d t is the frequency change rate.

[0193] Optionally, the transient power angle reshaping control model is:

[0194]

[0195] In the formula, is the power dynamic compensation amount, k is the compensation coefficient, U g is the initial amplitude of the grid voltage, U g1 is the amplitude when the power grid drops.

[0196] Optionally, the power angle stabilization control start criterion is:

[0197] Step 1: Collect the current angular velocity of the grid-type energy storage converter ω ;

[0198] Step 2: Determine the change in angular velocity Whether it exceeds the threshold ω t If it does not exceed, determine whether the fault is cleared. If the grid fault is cleared, end the algorithm. If the grid fault is not cleared, return to step 1.

[0199] Step 3: If the angular velocity change exceeds the threshold, determine whether the angular velocity change is positive or negative. If the angular velocity change is positive, execute , otherwise execute , after the execution is completed, return to step 1, where P in is the input power of the transient power angle stabilizer.

[0200] Optionally, the support module 1150 includes:

[0201] The first output submodule is used to output the potential phase of the converter according to the power angle stability control startup criterion and the frequency support capability criterion;

[0202] The second output submodule is used to output the internal potential of the converter according to the voltage support capability criterion;

[0203] The supporting submodule is used to support the power grid according to the potential phase in the converter and the potential in the converter.

[0204] Exemplary Electronic Devices

[0205] Fig.12 This is a structure of an electronic device provided by an exemplary embodiment of the present invention. Fig.12 As shown, the electronic device 120 includes one or more processors 121 and a memory 122 .

[0206] The processor 121 may be a central processing unit (CPU) or other forms of processing units having data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device to perform desired functions.

[0207] The memory 122 may include one or more computer program products, which may include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may include, for example, random access memory (RAM) and / or cache memory (cache), etc. The non-volatile memory may include, for example, read-only memory (ROM), hard disk, flash memory, etc. One or more computer program instructions may be stored on the computer-readable storage medium, and the processor 121 may run the program instructions to implement the methods of the software programs of the various embodiments of the present invention described above and / or other desired functions. In one example, the electronic device may also include: an input device 123 and an output device 124, which are interconnected via a bus system and / or other forms of connection mechanisms (not shown).

[0208] In addition, the input device 123 may also include, for example, a keyboard, a mouse, etc.

[0209] The output device 124 can output various information to the outside, and can include, for example, a display, a speaker, a printer, a communication network and a remote output device connected thereto.

[0210] Of course, to simplify, Fig.12 Only some of the components related to the present invention in the electronic device are shown, and components such as a bus, an input / output interface, etc. are omitted. In addition, the electronic device may further include any other appropriate components according to specific application conditions.

[0211] Exemplary computer program products and computer-readable storage media

[0212] In addition to the above-mentioned methods and devices, an embodiment of the present invention may also be a computer program product, which includes computer program instructions, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above-mentioned "Exemplary Method" section of this specification.

[0213] The computer program product may be written in any combination of one or more programming languages ​​to write program code for performing the operations of the embodiments of the present invention, including object-oriented programming languages ​​such as Java, C++, etc., and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code may be executed entirely on the user computing device, partially on the user device, as a separate software package, partially on the user computing device and partially on a remote computing device, or entirely on a remote computing device or server.

[0214] In addition, an embodiment of the present invention may also be a computer-readable storage medium having computer program instructions stored thereon, which, when executed by a processor, enable the processor to execute the steps of the method according to various embodiments of the present invention described in the above “Exemplary Method” section of this specification.

[0215] The computer readable storage medium can adopt any combination of one or more readable media. The readable medium can be a readable signal medium or a readable storage medium. The readable storage medium can include, for example, but is not limited to, a system, system or device of electricity, magnetism, light, electromagnetic, infrared, or semiconductor, or any combination of the above. More specific examples (non-exhaustive list) of readable storage media include: an electrical connection with one or more wires, a portable disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0216] The basic principle of the present invention is described above in conjunction with specific embodiments. However, it should be pointed out that the advantages, strengths, effects, etc. mentioned in the present invention are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. must be possessed by each embodiment of the present invention. In addition, the specific details disclosed above are only for the purpose of illustration and facilitation of understanding, rather than limitation, and the above details do not limit the present invention to being implemented by adopting the above specific details.

[0217] Each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system embodiment, since it basically corresponds to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0218] The block diagrams of the devices, systems, equipment, and systems involved in the present invention are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, systems, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The word "such as" used here refers to the phrase "such as but not limited to", and can be used interchangeably with it.

[0219] The method and system of the present invention may be implemented in many ways. For example, the method and system of the present invention may be implemented by software, hardware, firmware or any combination of software, hardware, firmware. The above order of steps for the method is only for illustration, and the steps of the method of the present invention are not limited to the order specifically described above, unless otherwise specifically stated. In addition, in some embodiments, the present invention may also be implemented as a program recorded in a recording medium, which includes machine-readable instructions for implementing the method according to the present invention. Thus, the present invention also covers a recording medium storing a program for executing the method according to the present invention.

[0220] It should also be noted that in the system, device and method of the present invention, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent schemes of the present invention. The above description of the disclosed aspects is provided to enable any technician in the field to make or use the present invention. Various modifications to these aspects are very obvious to those skilled in the art, and the general principles defined here can be applied to other aspects without departing from the scope of the present invention. Therefore, the present invention is not intended to be limited to the aspects shown here, but in accordance with the widest range consistent with the principles and novel features disclosed here.

[0221] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present invention to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A method for grid support using a grid-type energy storage converter remodeling controller, characterized in that: include: Constructing a voltage reshaping controller model of a grid-connected energy storage converter, and constructing a voltage support capability criterion of the voltage reshaping controller model; Constructing a frequency reshaping controller model of the grid-type energy storage converter and constructing a frequency support capability criterion of the frequency reshaping controller model, wherein the frequency reshaping controller model includes virtual frequency modulation control and virtual inertia and damping control; Constructing a transient power angle reshaping controller model of the grid-connected energy storage converter, and constructing a power angle stabilization control start criterion of the transient power angle reshaping controller model; According to the voltage reshaping controller model, the frequency reshaping controller model and the transient power angle reshaping controller model, a reshaping controller model of a grid-connected energy storage converter is constructed; Connecting the grid-forming energy storage converter to a power grid, and supporting the power grid according to the voltage support capability criterion, the frequency support capability criterion, and the power angle stability control start-up criterion of the remodeling controller model; The voltage reshaping controller model is: In the formula, E is the potential amplitude in the converter, K is the regulator gain, K v Select the factor for proportional-integral, T 1 and T 2 are the first voltage regulator time constant and the second voltage regulator time constant, U t * is the grid connection point voltage reference value, U t Grid connection voltage, is the time constant of the virtual excitation winding, s is the Laplace operator; The frequency reshaping controller model is: In the formula, J is the equivalent inertia time constant of the grid-type energy storage converter, K L is the equivalent damping coefficient of the grid-type energy storage converter, K VD is the transient damping control coefficient, is the potential phase in the converter, P ref is the power reference value, P is the output electromagnetic power, ω is the angular frequency of the energy storage converter, ω 0 is the angular frequency reference value, t For time; The transient power angle reshaping control model is: In the formula, △ P is the power dynamic compensation amount, k is the compensation coefficient, U g is the initial amplitude of the grid voltage, U g1 is the amplitude when the power grid drops.

2. The method according to claim 1, characterized in that Also included: using a particle swarm optimization algorithm to reshape the parameters of the voltage controller model T ’ d0 , T 1 and T 2Perform adjustment.

3. The method according to claim 2, characterized in that The parameters of the voltage reshaping controller model are optimized using a particle swarm optimization algorithm. T ’ d0 , T 1 and T 2. Perform tuning, including: Step 1: Generate a certain number of particles and initialize the particle dimension, particle position and particle velocity; Step 2: Assign the particle to the time constant T ’ d0 , T 1 and T 2. Run the simulation model, calculate the objective function, and generate the objective function value; Step 3: Compare the objective function values ​​in the iteration process and update the local optimal value of the particle and the global optimal solution; Step 4: updating the particle speed and position according to the particle local optimal value and the global optimal solution, and limiting the particle position and speed within a preset range; Step 5: Determine whether the maximum number of iterations has been reached or the convergence condition has been met. If so, terminate the algorithm and output the optimized T ’ d0 , T 1 and T 2, otherwise return to step 2 for iterative calculation, where the objective function is: In the formula, J is the equivalent inertia time constant of the grid-type energy storage converter, T is the time constant, t 0 is the time when the fault occurs.

4. The method according to claim 1, characterized in that: The voltage support capability criterion is: In the formula, U t is the grid connection point voltage; is the potential phase in the converter; Q is the reactive power; x c To connect the grid-type energy storage converter to the grid-connected point.

5. The method according to claim 1, characterized in that The frequency support capability criterion is: In the formula, k d is the damping proportional coefficient, k j is the inertia proportional coefficient, K W is the grid-type droop control coefficient, K n The proportion of new energy units participating in frequency regulation, J 1 is the inertia coefficient of virtual synchronous machine control, M d and M j They are K L and J The frequency change rate of the parameter starts the dead zone, △ f is the frequency change, d f / d t is the frequency change rate.

6. The method according to claim 1, characterized in that The power angle stabilization control start criterion is: Step 1: Collect the current angular velocity of the grid-type energy storage converter ω ; Step 2: Determine the change in angular velocity | ω - ω t │Whether it exceeds the threshold ω t If it does not exceed, determine whether the fault is cleared. If the grid fault is cleared, end the algorithm. If the grid fault is not cleared, return to step 1. Step 3: If the angular velocity change exceeds the threshold value, determine whether the angular velocity change is positive or negative. If the angular velocity change is positive, execute P in = P in -Δ P , otherwise execute P in = P in +Δ P , after the execution is completed, return to step 1, where P in is the compensation amount of the power reference value.

7. The method according to claim 1, characterized in that Supporting the power grid according to the voltage support capability criterion, the frequency support capability criterion and the power angle stability control start-up criterion of the remodeling controller model includes: Outputting the potential phase in the converter according to the power angle stability control start criterion and the frequency support capability criterion; outputting the internal potential of the converter according to the voltage support capability criterion; The power grid is supported according to the potential phase in the converter and the potential in the converter.

8. A device for grid support using a grid-type energy storage converter remodeling controller, characterized in that: include: A first construction module is used to construct a voltage reshaping controller model of a grid-connected energy storage converter and to construct a voltage support capability criterion of the voltage reshaping controller model; A second construction module is used to construct a frequency reshaping controller model of the grid-type energy storage converter and to construct a frequency support capability criterion of the frequency reshaping controller model, wherein the frequency reshaping controller model includes virtual frequency modulation control and virtual inertia and damping control; A third construction module is used to construct a transient power angle reshaping controller model of the grid-connected energy storage converter, and to construct a power angle stabilization control start criterion of the transient power angle reshaping controller model; A fourth construction module is used to construct a reshaping controller model of a grid-connected energy storage converter according to the voltage reshaping controller model, the frequency reshaping controller model and the transient power angle reshaping controller model; A support module, used to connect the grid-type energy storage converter to a power grid, and support the power grid according to the voltage support capability criterion, the frequency support capability criterion and the power angle stability control start-up criterion of the remodeling controller model; The voltage reshaping controller model is: In the formula, E is the potential amplitude in the converter, K is the regulator gain, K v Select the factor for proportional-integral, T 1 and T 2 are the first voltage regulator time constant and the second voltage regulator time constant, U t * is the grid connection point voltage reference value, U t Grid connection voltage, is the time constant of the virtual excitation winding, s is the Laplace operator; The frequency reshaping controller model is: In the formula, J is the equivalent inertia time constant of the grid-type energy storage converter, K L is the equivalent damping coefficient of the grid-type energy storage converter, K VD is the transient damping control coefficient, is the potential phase in the converter, P ref is the power reference value, P is the output electromagnetic power, ω is the angular frequency of the energy storage converter, ω 0 is the angular frequency reference value, t For time; The transient power angle reshaping control model is: In the formula, △ P is the power dynamic compensation amount, k is the compensation coefficient, U g is the initial amplitude of the grid voltage, U g1 is the amplitude when the power grid drops.

9. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and the computer program is used to execute the method according to any one of claims 1 to 7.

10. An electronic device, characterized in that: The electronic device comprises: processor; a memory for storing instructions executable by the processor; The processor is used to read the executable instructions from the memory and execute the instructions to implement the method described in any one of claims 1 to 7.

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