A method and device for active support control of a wind turbine and a medium

Abstract

The application discloses a kind of active support control method, device and medium of wind turbine, it is related to wind turbine active support control technical field, for the problem that current power grid voltage fault cannot identify power grid parameter, and then active support control effect is not good, provide a kind of active support control method of wind turbine.The voltage and current data of grid-connected point before and after power grid failure are collected to determine the parameter change of power grid before and after voltage failure.Furthermore, the short-circuit point position, short-circuit current and transition resistance value are identified, and the determination of all unknown quantities in the wind turbine grid-connected point voltage model after failure is realized.At this time, all parameters in the wind turbine grid-connected point voltage model after failure are known, the equivalent voltage and equivalent impedance of the power grid after failure can be determined, and the power grid parameter identification during failure is completed.Based on the identified power grid parameters during failure, the active and reactive output current optimal proportion of wind turbine can be redesigned, and better support for power grid voltage recovery effect is brought.

Description

Technical Field

[0001] This application relates to the field of active support control technology for wind turbine generators, and in particular to an active support control method, device and medium for wind turbine generators. Background Technology

[0002] With the rapid increase in wind power installed capacity, wind turbines under voltage faults must not only have the low-voltage ride-through capability to operate continuously without disconnecting from the grid, but also the ability to actively support grid voltage recovery. When the resistance in the wind farm's transmission line is much smaller than the inductive reactance, the wind turbines support grid voltage recovery by outputting reactive current under grid voltage faults.

[0003] Most existing wind turbines use reactive current droop factors for voltage support. However, when the wind turbine is located at the end of the grid, the premise that the resistance in the transmission line is much smaller than the inductive reactance is not necessarily true. With a fixed total current capacity, more reactive current output does not necessarily lead to greater voltage recovery at the grid connection point. Therefore, the ratio of active to reactive current output by the wind turbine needs to be redesigned. The optimal ratio is related to the grid impedance, but grid parameters differ between during fault periods and normal operating conditions, requiring re-identification.

[0004] Therefore, those skilled in the art urgently need an active support control method for wind turbines to solve the problem of grid parameter identification during grid voltage faults, and to redesign the optimal ratio of active and reactive power output current of wind turbines based on the identified grid parameters. Summary of the Invention

[0005] The purpose of this application is to provide an active support control method, device and medium for wind turbine generators, which can identify grid parameters when the grid voltage fails, and redesign the optimal ratio of active and reactive power output current of the wind turbine generators based on the identified grid parameters.

[0006] To address the aforementioned technical problems, this application provides an active support control method for wind turbine generators, comprising:

[0007] Collect voltage and current data at the grid connection point before and after a power grid fault;

[0008] The location of the short circuit point and the short circuit current of the wind turbine can be identified by the grid connection point voltage and current data.

[0009] The value of the transition resistor is determined based on the location of the short circuit point and the short circuit current.

[0010] The equivalent voltage and equivalent impedance after a power grid fault are determined based on the location of the short circuit point, the short circuit current, and the resistance value of the transition resistor.

[0011] A new power command is generated based on the equivalent voltage and the equivalent impedance, and the wind turbine is controlled to support the recovery of grid voltage according to the new power command.

[0012] In one optional embodiment, identifying the short-circuit point location and short-circuit current of the wind turbine using the grid connection point voltage and current data includes:

[0013] The identification model is iteratively solved to obtain the location of the short circuit point and the short circuit current;

[0014] The identification model includes: a short-circuit point location expression and a short-circuit current expression;

[0015] The short-circuit point location expression is obtained by converting the wind turbine resistance grid connection point voltage expression based on the short-circuit loop. The conversion process includes multiplying both sides of the equal sign of the wind turbine resistance grid connection point voltage expression based on the short-circuit loop by the conjugate complex number of the short-circuit current, and retaining only the imaginary part.

[0016] The short-circuit current expression is obtained by transforming the expression for the grid connection point voltage of the wind turbine based on the power grid loop.

[0017] In one optional embodiment, the iterative solution of the identification model to obtain the short-circuit point location and the short-circuit current includes:

[0018] For each iteration in the iterative process, including:

[0019] Get the short-circuit point location result value from the previous iteration; if this iteration is the first iteration, get the initial result value.

[0020] Determine the short-circuit current value based on the short-circuit current expression;

[0021] Substitute the short-circuit current result into the short-circuit point location expression, and perform a safety check on the short-circuit point location expression;

[0022] If the security check fails, an error will be reported and the iteration process will be terminated;

[0023] If the safety check passes, the candidate value of the short circuit point location is determined according to the short circuit point location expression;

[0024] The convergence condition is used to determine whether the candidate short-circuit point location has converged; wherein, the convergence condition is: the residual after substituting the candidate short-circuit point location into the short-circuit current expression is less than the tolerance, and the change in the short-circuit point location is less than the tolerance.

[0025] If convergence is achieved, the iteration process ends.

[0026] If convergence is not achieved, the average of the candidate short-circuit point location value and the short-circuit point location result value of the previous iteration is processed by physical constraints and used as the short-circuit point location result value of the current iteration; and the process proceeds to the next iteration.

[0027] In an optional embodiment, the short-circuit point location expression is:

[0028] ;

[0029] In the formula, m represents the location of the short-circuit point, with a value range of [0, 1]; Im() represents the imaginary part of the complex number; U wt This indicates the grid connection voltage of the wind turbine generator set; Z represents the conjugate complex number of the short-circuit current; g Indicates the impedance of the transmission line; I wt This indicates the output current of the wind turbine generator;

[0030] The expression for the short-circuit current is:

[0031] ;

[0032] In the formula, I f U represents the short-circuit current; g This indicates the grid voltage.

[0033] In one alternative embodiment, generating a new power command based on the equivalent voltage and the equivalent impedance includes:

[0034] The power command is determined using a power optimization model;

[0035] The objective function of the power optimization model is:

[0036] ;

[0037] In the formula, obj represents the optimization objective; min() represents taking the minimum value; U wt U represents the grid connection point voltage of the wind turbine; U0 represents the rated value of the grid connection point voltage of the wind turbine; c represents the weighting coefficient of the optimization objective; P wt P represents the active power output of the wind turbine generator; 0,wt This indicates the active power output of the wind turbine before the fault.

[0038] The constraints of the power optimization model include: voltage constraints, current constraints, and power constraints.

[0039] The voltage constraint is:

[0040] ;

[0041] In the formula, U g,th Represents the equivalent voltage; R th and X th These represent the equivalent resistance of the power grid and the equivalent inductive reactance of the power grid in the equivalent impedance, respectively; I d,wt and I q,wt These represent the active and reactive components of the wind turbine's output current, respectively.

[0042] The current constraint is:

[0043] ;

[0044] In the formula, I max,wt This indicates the maximum safe current output by the wind turbine.

[0045] The power constraint is:

[0046] ;

[0047] In the formula, P limit,wt This indicates the upper limit of the active power output of the wind turbine.

[0048] In one optional embodiment, determining the power command through a power optimization model includes:

[0049] The power optimization model is transformed into a second-order cone form;

[0050] The power optimization model, after being transformed into a second-order cone form, is solved to determine the optimal active current, optimal reactive current, and optimal voltage.

[0051] The active power command is determined based on the optimal active current and the optimal voltage, and the reactive power command is determined based on the optimal reactive current and the optimal voltage.

[0052] In an optional embodiment, the power optimization model, after being transformed into a second-order cone form, is as follows:

[0053] ;

[0054] In the formula, st represents the constraint condition.

[0055] To address the aforementioned technical problems, this application also provides an active support control device for wind turbine generators, comprising:

[0056] The data acquisition module is used to collect voltage and current data at the grid connection point before and after a power grid fault.

[0057] The first identification module is used to identify the short-circuit point location and short-circuit current of the wind turbine through the grid connection point voltage and current data;

[0058] The second identification module is used to determine the value of the transition resistor based on the location of the short circuit point and the short circuit current.

[0059] The third identification module is used to determine the equivalent voltage and equivalent impedance after a power grid fault based on the location of the short circuit point, the short circuit current, and the resistance value of the transition resistor.

[0060] The collaborative support module is used to generate a new power command based on the equivalent voltage and the equivalent impedance, and control the wind turbine to support the recovery of grid voltage according to the new power command.

[0061] To address the aforementioned technical problems, this application also provides an active support control device for wind turbine generators, comprising:

[0062] Memory, used to store computer programs;

[0063] A processor is used to execute the computer program to implement the steps of the active support control method for wind turbines as described above.

[0064] To address the aforementioned technical problems, this application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the active support control method for wind turbine generators as described above.

[0065] This application provides an active support control method for wind turbines. By collecting grid connection point voltage and current data before and after a grid fault, the method determines the parameter changes of the power grid before and after the fault. Furthermore, it identifies unknowns in the wind turbine grid connection point voltage based on the short-circuit loop after the fault, including the short-circuit location, transition resistance value, and short-circuit current. First, the short-circuit location and short-circuit current are identified using the grid connection point voltage and current data before and after the fault. Then, the transition resistance value is determined using the short-circuit location and short-circuit current, thus determining all unknowns in the wind turbine grid connection point voltage model after the fault. At this point, since all parameters in the wind turbine grid connection point voltage model after the fault are known, the equivalent voltage and equivalent impedance of the power grid after the fault can be determined, completing the identification of power grid parameters during the fault period. Based on the identified power grid parameters during the fault period, the optimal ratio of active and reactive power output current of the wind turbine can be redesigned, resulting in better support for grid voltage recovery.

[0066] The active support control device for wind turbines and the computer-readable storage medium provided in this application correspond to the above-mentioned method and have the same effect. Attached Figure Description

[0067] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0068] Figure 1 A flowchart of an active support control method for a wind turbine provided in an embodiment of the present invention;

[0069] Figure 2 An equivalent circuit diagram of a power system during a symmetrical voltage fault is provided in an embodiment of the present invention;

[0070] Figure 3 A structural diagram of an active support control device for a wind turbine provided in an embodiment of the present invention;

[0071] Figure 4 This is a structural diagram of another active support control device for wind turbines provided in an embodiment of the present invention. Detailed Implementation

[0072] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0073] The core of this application is to provide an active support control method, device, and medium for wind turbine generators.

[0074] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0075] In related technologies, current wind turbines mostly use a reactive current droop factor to achieve voltage support. Specifically, when a symmetrical voltage dip occurs in the grid, the required reactive current output by the wind turbine is:

[0076] ;

[0077] In the formula, I q,wt I represents the reactive component of the wind turbine's output current. 0,wt U represents the reactive component of the wind turbine's output current before the voltage fault occurs; K represents the reactive current droop factor; U wt Indicates the grid connection point voltage of the wind turbine generator; I rat,wtThis represents the rated current of the wind turbine generator; all parameters in the above formula are per-unit values.

[0078] However, the above solution has a problem: when the wind turbine is located at the end of the grid, the premise that the resistance in the transmission line is much smaller than the inductive reactance may not hold true. With a fixed total current capacity, more reactive current output does not necessarily lead to greater voltage recovery at the grid connection point. Therefore, the ratio of active to reactive current output by the wind turbine needs to be redesigned. This optimal ratio is related to the grid impedance, and the grid parameters during a fault differ from those under normal operating conditions, requiring re-identification. In other words, how to identify the equivalent grid parameters during a voltage fault has become a key issue restricting the support control of wind turbines.

[0079] To address the aforementioned problems, this application provides an active support control method for wind turbine generators, such as... Figure 1 As shown, it includes:

[0080] S10: Collect voltage and current data at the grid connection point before and after a power grid fault.

[0081] S21: Identify the short-circuit point location and short-circuit current of the wind turbine unit using grid connection voltage and current data.

[0082] S22: Determine the value of the transition resistor based on the location of the short circuit point and the short circuit current.

[0083] S23: Determine the equivalent voltage and equivalent impedance after a power grid fault based on the location of the short circuit point, the short circuit current, and the value of the transition resistance.

[0084] S30: Generates a new power command based on the equivalent voltage and equivalent impedance, and controls the wind turbine to support grid voltage recovery according to the new power command.

[0085] For step S10, voltage and current are common parameters in wind turbine operation control. Current wind turbines already have circuits or devices deployed for collecting voltage and current at the grid connection point, requiring no additional setup. The focus of this step is to collect voltage and current data at the grid connection point before and after a grid fault. In an optional embodiment, the collection of grid connection point voltage and current data after a grid fault can wait until the wind turbine reaches a steady state before collecting the data, thereby improving the accuracy of subsequent identification.

[0086] Steps S21-S23 involve identifying the grid parameters after a grid fault. In this method, the purpose of identifying these parameters is to support the grid voltage to restore it to its rated value and to redesign the active and reactive current output ratios of the wind turbine generators. Since this output ratio is related to the grid impedance, the grid parameters to be identified in this method are the grid equivalent voltage and equivalent impedance.

[0087] Specifically, voltage dips in the power grid are commonly caused by short-circuit faults in transmission lines. In this case, the voltage at the wind turbine's grid connection point will also drop accordingly, causing the wind turbine to enter a low-voltage ride-through state. However, short-circuit faults in high-voltage transmission lines are generally not metallic; rather, there is a transition resistance at the short-circuit point. Therefore, the system structure when a short-circuit fault occurs in a transmission line is as follows: Figure 2 As shown. Figure 2 Middle,U wt Indicates the grid connection point voltage of the wind turbine generator; I wt Z represents the output current of the wind turbine; g Indicates the transmission line impedance; m represents the short-circuit point location, with a value range of [0, 1]; U g Represents the power grid (i.e.) Figure 2 (Voltage of an infinite power grid in the universe); R f Indicates the resistance value of the transition resistor; I f This represents the short-circuit current flowing through the transition resistor.

[0088] based on Figure 2 The short-circuit fault system structure shown can be represented by the grid connection point voltage of the wind turbine based on the short-circuit loop as follows:

[0089] (1);

[0090] Among them, Z g The value of does not change before and after the fault, and does not need to be re-identified; while U wt and I wt That is, the grid connection point voltage and current data collected in step S10 can be obtained by wind turbine measurement; that is, only m and R remain in equation (1). f and I f Since it is an unknown quantity, it needs to be re-identified.

[0091] In steps S21 to S23, m and I are first calculated. f Then through m and I f Determine R f m and I f The expressions can all be obtained by transforming or transforming the above equation (1), and this embodiment does not impose any restrictions on this.

[0092] In an alternative embodiment, the short-circuit current can be multiplied by the conjugate complex number of both sides of the equation (1) above. And retaining only the imaginary part, we obtain the expression for the short-circuit point position m:

[0093] (2);

[0094] In the formula, Im() represents the imaginary part of the complex number; It represents the conjugate complex number of the short-circuit current.

[0095] However, in equation (2) The unknowns remain; an equation with two unknowns cannot yield a unique solution. Based on this, the expression for the grid connection point voltage of the wind turbine is further derived by transforming equation (1) above:

[0096] (3);

[0097] Among them, due to U g The value of did not change before and after the power grid fault. Therefore, based on equation (3), the expression for the short-circuit current can be further derived:

[0098] (4);

[0099] Based on this, equation (4) and equation (2) above constitute an identification model containing two unknowns and consisting of two equations, which can be used to identify the short-circuit point location m and the circuit current I. f .

[0100] Based on this, the identification model composed of equations (2) and (4) above can be solved directly, or it can be solved by iteration, etc. This embodiment does not restrict this. In an optional embodiment, the identification model is solved by iteration to obtain the short-circuit point location m and the circuit current I. f .

[0101] Furthermore, since iterative solving is a common mathematical method, and various mature iterative schemes exist for different needs in practical applications, this embodiment does not impose any limitations on it. However, in an optional embodiment, this application also provides a specific iterative process:

[0102] For the k-th iteration in the iterative process, the steps include:

[0103] Step 1: Obtain the short-circuit point location result value m(k) of the previous iteration; where, if this iteration is the first iteration, obtain the initial result value m(0).

[0104] Step 2: Determine the short-circuit current result value I according to the short-circuit current expression (4). f (k).

[0105] Step 3: Substitute the short-circuit current result into the short-circuit point location expression and perform a safety check on the short-circuit point location expression; if the safety check fails, report an error and terminate the iteration process; if the safety check passes, proceed to Step 4.

[0106] The purpose of this step is to perform a safety check on equation (2) before obtaining the short-circuit point location m, so as to avoid division by zero error, which would result in an infinitely large result.

[0107] Optionally, this can be determined by checking whether the absolute value of the denominator in formula (2) is less than 10. -12 To determine if a division by zero error will occur. This applies when the absolute value of the denominator is less than 10. -12 When the denominator is zero, it can be approximated that the division by zero error will occur.

[0108] Step 4: Determine the candidate value m of the short-circuit point location based on the short-circuit point location expression (2). new .

[0109] Step 5: Determine the candidate value m for the short-circuit point location based on the convergence condition. new Whether it converges.

[0110] The convergence conditions include:

[0111] 1) The residual after substituting the candidate short-circuit point location values ​​into the short-circuit current expression is less than the tolerance (used to verify I). f (Whether it is self-consistent).

[0112] 2) The change in the location of the short circuit point is less than the tolerance.

[0113] m is considered to be true only if both of the above convergence conditions are satisfied simultaneously. new Convergence occurs, at which point the iterative process ends, and the I determined in this iteration... f (k) and m new This is the short-circuit current I obtained in the final iteration. f And the location of the short circuit point m. If convergence is not achieved, proceed to step 6.

[0114] Step 6: Select candidate values ​​m for short-circuit point locations new The average of the short-circuit point location results m(k) from the previous iteration, i.e., m(k+1) = [m(k) + m new After being processed by physical constraints, m(k+1) is used as the short-circuit point location result for this iteration and will proceed to the next iteration.

[0115] The physical constraints are the physical boundaries that limit m(k+1). Generally, physical constraints include: if m(k+1) < 0, forcing m(k+1) to be 0; and if m(k+1) > N, forcing m(k+1) to be N, where X is a value less than 1 but infinitely close to 1 (such as 0.99), the purpose of which is to avoid the denominator being zero when m = 1.

[0116] Furthermore, in addition to satisfying the above convergence conditions, a maximum number of iterations can be set. The iteration process also ends when the maximum number of iterations is reached, and the I determined in the last iteration is... f (k) and m new The short-circuit current I obtained in the final iteration f And the location of the short circuit point m.

[0117] Based on the iterative identification method provided in this embodiment, it can adapt to the characteristics of complex calculations performed by hardware circuits, decompose complex calculations into multiple simple calculations, thereby improving the efficiency and accuracy of identifying power grid parameters after a fault.

[0118] Furthermore, in determining the short-circuit current I f After the short-circuit point location m, the remaining unknown quantity is the resistance value R of the transition resistor. f Identification is performed. The resistance value of the transition resistor can be obtained using the following formula:

[0119] (5);

[0120] Now that all parameters in equation (1) are known, the equivalent voltage of the power grid can be determined as shown in equation (6) and the equivalent impedance of the power grid can be determined as shown in equation (7) according to Thevenin's equivalent theorem.

[0121] (6);

[0122] (7);

[0123] In the formula, U g,th Z represents the equivalent voltage of the power grid. th This represents the equivalent impedance of the power grid, which is determined by the equivalent resistance R of the power grid. th and equivalent sense X th Composition; j is the imaginary unit.

[0124] At this point, the identification of the equivalent voltage and equivalent resistance after a grid fault is complete, which can then be used to generate the optimal power output ratio to support grid voltage recovery, and subsequently generate the corresponding power command. Since the design of the reactive and active power ratio of the wind turbine current output and the method to support grid voltage recovery are known given the equivalent voltage and equivalent resistance, this embodiment will not elaborate on these aspects.

[0125] In summary, the active support control method for wind turbines provided in this application can re-identify the faulty grid parameters using the voltage and current data at the grid connection point after a grid fault. Furthermore, based on the re-identified equivalent grid voltage and equivalent impedance, the active and reactive power ratios of the wind turbine output current are redesigned to support grid voltage recovery.

[0126] On the other hand, as mentioned above, wind turbines support grid voltage recovery by outputting reactive current. However, as the proportion of wind power output in the total system output gradually increases, if wind turbines output a large amount of reactive current to support grid recovery during voltage faults, the active power output of the wind turbines may experience a sudden drop. This could lead to system frequency fluctuations, and in severe cases, even a drop in system frequency. Therefore, it is necessary to further improve the coordinated support performance of wind turbines for grid connection frequency and voltage.

[0127] To address the aforementioned issues, this application, based on the above embodiments, provides a grid connection point voltage-frequency coordinated support scheme. Specifically, step S30, generating a new power command based on equivalent voltage and equivalent impedance, further includes: determining the power command through a power optimization model.

[0128] As described above, the purpose of this embodiment is to provide a coordinated control method that supports grid voltage recovery without causing a drop in the grid connection point frequency. The objective function of the power optimization model is as follows:

[0129] (8);

[0130] In the formula, obj represents the optimization objective; min() represents taking the minimum value; U0 represents the rated voltage of the wind turbine grid connection point; P wt P represents the active power output of the wind turbine generator; 0,wt denoted by , represents the active power output of the wind turbine before the fault; c represents the weighting coefficient of the optimization target; when the frequency deviation at the grid connection point is small, the wind turbine should mainly support the recovery of the grid connection point voltage; while when the frequency deviation at the grid connection point is large, the wind turbine should strengthen its support for the grid connection point frequency; therefore, the value of c can gradually increase as the degree of frequency drop at the grid connection point deepens.

[0131] Accordingly, the constraints of the power optimization model can specifically include voltage constraints, current constraints, and power constraints.

[0132] The voltage constraint can be expressed as:

[0133] (9);

[0134] In the formula, the first term is the grid connection point voltage equation, I d,wt and I q,wt The first term represents the active and reactive components of the wind turbine's output current, respectively; the second term represents the steady-state equilibrium point constraint; and the third term represents the feasibility constraint.

[0135] Current constraint can be expressed as:

[0136] (10);

[0137] In the formula, I max,wt This indicates the maximum safe current output by the wind turbine.

[0138] The power constraint can be expressed as:

[0139] (11);

[0140] In the formula, P limit,wt This indicates the upper limit of the active power output of the wind turbine.

[0141] Based on the power optimization model composed of equations (8) to (11) above, I can be solved. d,wt I q,wt and U wt The optimal solution is the optimal active current, optimal reactive current, and optimal voltage. Based on the power formula, the power can be obtained from the current and voltage, that is, the optimal active power and optimal reactive power output of the wind turbine resistance can be obtained, so as to generate the corresponding active power command and reactive power command.

[0142] As described above, this embodiment incorporates the frequency drop issue that may occur when wind turbines support grid voltage through reactive current output into the support control considerations, providing a voltage-frequency coordinated support control method. Based on the calculation of the optimal active and reactive power ratio, it ensures effective support and recovery of grid voltage while avoiding frequency fluctuations at the grid connection point, achieving better wind turbine support control performance.

[0143] However, furthermore, although the above embodiments can achieve voltage-frequency coordinated support control, it can be seen from equations (8) to (11) that this optimization model is a typical non-convex optimization problem, and its solution efficiency is difficult to guarantee. It needs to be transformed into a convex optimization problem to improve the solution efficiency. Since there are 2-norm terms in both the optimization objective and the constraints, it is possible to try to transform the optimization model into a second-order cone programming problem to improve the solution efficiency.

[0144] Based on this, this embodiment provides a further implementation scheme, wherein step S30 above: determining the power command through a power optimization model, specifically includes:

[0145] S31: Transform the power optimization model into a second-order cone form.

[0146] S32: Solve the power optimization model after it has been transformed into a second-order cone form to determine the optimal active current, optimal reactive current and optimal voltage.

[0147] S33: Determine the active power command based on the optimal active current and optimal voltage, and determine the reactive power command based on the optimal reactive current and optimal voltage.

[0148] In step S31, the power optimization model is transformed into a second-order cone form. First, the radical term in equation (9) is converted to a square term, and the resulting expression is shown below:

[0149] (12);

[0150] Then, by scaling equation (12), we get:

[0151] (13);

[0152] Comparing equations (9) and (13), it can be found that both the steady-state equilibrium point constraint and the feasibility constraint in the voltage constraint are included in equation (13). That is, the voltage constraint has been simplified from three terms to one.

[0153] Then, the active power expression in equation (8) is converted into a second-order cone form:

[0154] (14);

[0155] Thus, the cooperative support power optimization model for the wind turbine resistance, which has been converted into a second-order cone form, is shown below:

[0156] (15);

[0157] In the formula, st represents the constraint condition.

[0158] The power optimization model shown by solving equation (15) can also achieve coordinated support for the frequency and voltage at the grid connection point. Moreover, the computational efficiency is significantly higher than that of solving the original power optimization model equations (8) to (11). When the support control method provided in this embodiment is applied to the active support control of actual wind turbine units, it can bring faster response speed and better control effect.

[0159] In the above embodiments, a method for active support control of wind turbine generators has been described in detail. This application also provides an embodiment of an active support control device for wind turbine generators. It should be noted that this application describes the embodiments of the device from two perspectives: one based on functional modules and the other based on hardware.

[0160] From the perspective of functional modules, such as Figure 3 As shown, this embodiment provides an active support control device for a wind turbine, including:

[0161] The data acquisition module 11 is used to collect voltage and current data at the grid connection point before and after a power grid fault.

[0162] The first identification module 12 is used to identify the short-circuit point location and short-circuit current of the wind turbine through grid connection point voltage and current data.

[0163] The second identification module 13 is used to determine the value of the transition resistor based on the location of the short circuit point and the short circuit current.

[0164] The third identification module 14 is used to determine the equivalent voltage and equivalent impedance after a power grid fault based on the location of the short circuit point, the short circuit current, and the value of the transition resistance.

[0165] The collaborative support module 15 is used to generate new power commands based on equivalent voltage and equivalent impedance, and control the wind turbine to support grid voltage recovery according to the new power commands.

[0166] Since the embodiments of the apparatus and the embodiments of the method correspond to each other, please refer to the description of the embodiments of the method for the embodiments of the apparatus, which will not be repeated here.

[0167] Figure 4 A structural diagram of an active support control device for a wind turbine generator provided in another embodiment of this application is shown below. Figure 4 As shown, an active support control device for a wind turbine includes: a memory 20 for storing computer programs;

[0168] The processor 21 is used to execute a computer program to implement the steps of an active support control method for a wind turbine as described in the above embodiment.

[0169] The active support control device for wind turbines provided in this embodiment may include, but is not limited to, computers, workstations, etc.

[0170] The processor 21 may include one or more processing cores, such as a quad-core processor or an octa-core processor. The processor 21 may be implemented using at least one of the following hardware forms: Digital Signal Processor (DSP), Field-Programmable Gate Array (FPGA), or Programmable Logic Array (PLA). The processor 21 may also include a main processor and a coprocessor. The main processor, also known as the Central Processing Unit (CPU), is used to process data in the wake-up state; the coprocessor is a low-power processor used to process data in the standby state. In some embodiments, the processor 21 may integrate a Graphics Processing Unit (GPU), which is responsible for rendering and drawing the content to be displayed on the screen. In some embodiments, the processor 21 may also include an Artificial Intelligence (AI) processor, which is used to handle computational operations related to machine learning.

[0171] The memory 20 may include one or more computer-readable storage media, which may be non-transitory. The memory 20 may also include high-speed random access memory and non-volatile memory, such as one or more disk storage devices or flash memory devices. In this embodiment, the memory 20 is used to store at least the following computer program 201, which, after being loaded and executed by the processor 21, can implement the relevant steps of the active support control method for a wind turbine disclosed in any of the foregoing embodiments. In addition, the resources stored in the memory 20 may also include an operating system 202 and data 203, and the storage method may be temporary or permanent storage. The operating system 202 may include Windows, Unix, Linux, etc. The data 203 may include, but is not limited to, an active support control method for a wind turbine.

[0172] In some embodiments, an active support control device for a wind turbine may further include a display screen 22, an input / output interface 23, a communication interface 24, a power supply 25, and a communication bus 26.

[0173] Those skilled in the art will understand that Figure 4 The structure shown does not constitute a limitation on an active support control device for a wind turbine and may include more or fewer components than shown.

[0174] This application provides an active support control device for a wind turbine, which includes a memory and a processor. When the processor executes the program stored in the memory, it can implement the following method: an active support control method for a wind turbine.

[0175] Finally, this application also provides an embodiment corresponding to a computer-readable storage medium. The computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps described in the above method embodiments.

[0176] It is understood that if the methods in the above embodiments are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and executes all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0177] The above provides a detailed description of the active support control method, device, and medium for wind turbine generators provided in this application. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of this application.

[0178] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. An active support control method for wind turbine generators, characterized in that, include: Collect voltage and current data at the grid connection point before and after a power grid fault; The location of the short circuit point and the short circuit current of the wind turbine can be identified by the grid connection point voltage and current data. The value of the transition resistor is determined based on the location of the short circuit point and the short circuit current. The equivalent voltage and equivalent impedance after a power grid fault are determined based on the location of the short circuit point, the short circuit current, and the resistance value of the transition resistor. A new power command is generated based on the equivalent voltage and the equivalent impedance, and the wind turbine is controlled to support the recovery of grid voltage according to the new power command.

2. The active support control method for wind turbine generators according to claim 1, characterized in that, The step of identifying the short-circuit point location and short-circuit current of the wind turbine using the grid connection point voltage and current data includes: The identification model is iteratively solved to obtain the location of the short circuit point and the short circuit current; The identification model includes: a short-circuit point location expression and a short-circuit current expression; The short-circuit point location expression is obtained by converting the wind turbine resistance grid connection point voltage expression based on the short-circuit loop. The conversion process includes multiplying both sides of the equal sign of the wind turbine resistance grid connection point voltage expression based on the short-circuit loop by the conjugate complex number of the short-circuit current, and retaining only the imaginary part. The short-circuit current expression is obtained by transforming the expression for the grid connection point voltage of the wind turbine based on the power grid loop.

3. The active support control method for wind turbine generators according to claim 2, characterized in that, The iterative solution of the identification model to obtain the short-circuit point location and the short-circuit current includes: For each iteration in the iterative process, including: Get the short-circuit point location result value from the previous iteration; if this iteration is the first iteration, get the initial result value. Determine the short-circuit current value based on the short-circuit current expression; Substitute the short-circuit current result into the short-circuit point location expression, and perform a safety check on the short-circuit point location expression; If the security check fails, an error will be reported and the iteration process will be terminated; If the safety check passes, the candidate value of the short circuit point location is determined according to the short circuit point location expression; The convergence condition is used to determine whether the candidate short-circuit point location has converged; wherein, the convergence condition is: the residual after substituting the candidate short-circuit point location into the short-circuit current expression is less than the tolerance, and the change in the short-circuit point location is less than the tolerance. If convergence is achieved, the iteration process ends. If convergence is not achieved, the average of the candidate short-circuit point location value and the short-circuit point location result value of the previous iteration is processed by physical constraints and used as the short-circuit point location result value of the current iteration; and the process proceeds to the next iteration.

4. The active support control method for wind turbine generators according to claim 3, characterized in that, The expression for the short-circuit point location is: ； In the formula, m represents the location of the short-circuit point, with a value range of [0, 1]; Im() represents the imaginary part of the complex number; U wt This indicates the grid connection voltage of the wind turbine generator set; Z represents the conjugate complex number of the short-circuit current; g Indicates the impedance of the transmission line; I wt This indicates the output current of the wind turbine generator; The expression for the short-circuit current is: ； In the formula, I f U represents the short-circuit current; g This indicates the grid voltage.

5. The active support control method for wind turbine generators according to any one of claims 1 to 4, characterized in that, The generation of a new power command based on the equivalent voltage and the equivalent impedance includes: The power command is determined using a power optimization model; The objective function of the power optimization model is: ； In the formula, obj represents the optimization objective; min() represents taking the minimum value; U wt U represents the grid connection point voltage of the wind turbine; U0 represents the rated value of the grid connection point voltage of the wind turbine; c represents the weighting coefficient of the optimization objective; P wt P represents the active power output of the wind turbine generator. 0,wt This indicates the active power output of the wind turbine before the fault. The constraints of the power optimization model include: voltage constraints, current constraints, and power constraints. The voltage constraint is: ； In the formula, U g,th Represents the equivalent voltage; R th and X th These represent the equivalent resistance of the power grid and the equivalent inductive reactance of the power grid in the equivalent impedance, respectively; I d,wt and I q,wt These represent the active and reactive components of the wind turbine's output current, respectively. The current constraint is: ； In the formula, I max,wt This indicates the maximum safe current output by the wind turbine. The power constraint is: ； In the formula, P limit,wt This indicates the upper limit of the active power output of the wind turbine.

6. The active support control method for wind turbine generators according to claim 5, characterized in that, Determining the power command through a power optimization model includes: The power optimization model is transformed into a second-order cone form; The power optimization model, after being transformed into a second-order cone form, is solved to determine the optimal active current, optimal reactive current, and optimal voltage. The active power command is determined based on the optimal active current and the optimal voltage, and the reactive power command is determined based on the optimal reactive current and the optimal voltage.

7. The active support control method for wind turbine generators according to claim 6, characterized in that, The power optimization model, after being transformed into a second-order cone form, is as follows: ； In the formula, st represents the constraint condition.

8. An active support control device for a wind turbine generator, characterized in that, include: The data acquisition module is used to collect voltage and current data at the grid connection point before and after a power grid fault. The first identification module is used to identify the short-circuit point location and short-circuit current of the wind turbine through the grid connection point voltage and current data; The second identification module is used to determine the value of the transition resistor based on the location of the short circuit point and the short circuit current. The third identification module is used to determine the equivalent voltage and equivalent impedance after a power grid fault based on the location of the short circuit point, the short circuit current, and the resistance value of the transition resistor. The collaborative support module is used to generate a new power command based on the equivalent voltage and the equivalent impedance, and control the wind turbine to support the recovery of grid voltage according to the new power command.

9. An active support control device for a wind turbine generator, characterized in that, include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the steps of the active support control method for wind turbines as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the active support control method for wind turbine generators as described in any one of claims 1 to 7.

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