Active-reactive coordinated support method and system for grid-forming wind turbine generator

Abstract

The application discloses a kind of active-reactive coordinated support method and system of network type wind turbine, method includes: collecting grid-connected point three-phase voltage current, extracting positive and negative sequence components, and with first-order current closed loop and equivalent sequence impedance prediction candidate current execution value and sequence voltage;With predicted execution positive and negative sequence currents are transformed to the same stationary coordinate and synthesized three-phase current, constructs phase current safety domain;With positive sequence voltage direction affine lower limit and negative sequence voltage amplitude upper limit constraint, under the condition of keeping the average active power calculated from actual measurement sequence voltage unchanged, sequence current dictionary sequence optimization is executed;With the double threshold of positive and negative sequence minimum residual overrun, trigger joint optimization in the same safety domain;Output safety sequence current reference.Keep optimization problem as second-order cone form, unnecessary active reduction can be reduced, and each phase overcurrent constraint, positive sequence voltage support and negative sequence voltage suppression are considered.

Description

Technical Field

[0001] This invention belongs to the field of new energy power generation grid connection and grid-type converter control technology, and particularly relates to a method and system for coordinated active and reactive power support of grid-type wind turbine units. Background Technology

[0002] Grid-connected wind turbines can establish AC voltage and provide voltage and frequency support through grid-side converters, which is one of the key technologies for achieving stable operation of high-proportion renewable energy power systems. When the grid experiences voltage dips, especially asymmetrical faults, the converter needs to inject support current into the grid to maintain the grid connection point voltage. Meanwhile, the converter's own power semiconductor devices, filters, and modulation circuits have clearly defined current and voltage capability boundaries. Therefore, control commands need to be coordinated between dynamic support objectives and converter safety.

[0003] Under asymmetrical fault conditions, positive-sequence and negative-sequence currents are superimposed in the three phases at different phases. If only the amplitudes of the positive-sequence and negative-sequence currents are limited separately, the resulting sequence current combination may not guarantee that the actual current of each phase A, B, and C is within the allowable range; if only the steady-state apparent power boundary is used, it is also difficult to reflect the actual phase current formed in the next control cycle after the candidate current passes through the current closed loop.

[0004] On the other hand, directly releasing active power when the voltage deviates from the target may overlook the positive and negative sequence current regulation degrees of freedom that still exist when maintaining the current average active power. Especially under asymmetrical operating conditions, maintaining average active power is not equivalent to fixing a certain positive sequence d-axis current; the positive and negative sequence voltage and current jointly determine the average power. Therefore, it is necessary to first obtain the optimal sequence voltage support result achievable under the condition of maintaining average active power within a unified three-phase actual current boundary, and then determine whether to open the active power degree of freedom based on the remaining positive and negative sequence limits, ensuring that both stages maintain a convex optimization form that can be solved in real time.

[0005] In the existing technology, grid-type converters still have the following shortcomings in active and reactive power coordinated control: First, the independent limiting of sequence current cannot directly guarantee the safety of the three-phase predicted execution current; Second, the constraint of the lower limit of positive sequence voltage amplitude causes the optimization model to be non-convex, making it difficult to solve in real time; Third, the premature opening of active power regulation leads to unnecessary power generation loss, affecting the economic efficiency of wind turbine units. Summary of the Invention

[0006] The purpose of this invention is to provide a method and system for coordinated active and reactive power support of grid-connected wind turbine generators, in order to solve the problems that independent limiting of the lower sequence current under asymmetrical faults cannot directly guarantee the safety of the three-phase predicted execution current, the lower limit of the positive sequence voltage amplitude leads to optimization non-convexity, and the premature opening of active power regulation.

[0007] In a first aspect, the present invention provides a method for coordinated active and reactive power support of a grid-connected wind turbine generator, comprising: The three-phase voltage and three-phase current at the grid connection point are collected. After positive-sequence and negative-sequence separation, the positive-sequence voltage d-axis and q-axis components, positive-sequence current d-axis and q-axis components, negative-sequence voltage d-axis and q-axis components, and negative-sequence current d-axis and q-axis components are obtained. All d-axis and q-axis components are transformed to the same stationary complex phasor coordinate system to obtain the measured positive-sequence voltage phasor, measured positive-sequence current phasor, measured negative-sequence voltage phasor, and measured negative-sequence current phasor. Based on the candidate positive-sequence current reference and the candidate negative-sequence current reference, and using the measured positive-sequence current phasor and the measured negative-sequence current phasor as the current state variables, the predicted execution positive-sequence current phasor and the predicted execution negative-sequence current phasor are recursively obtained through a first-order current closed-loop model. Based on the predicted execution positive-sequence current phasor and the predicted execution negative-sequence current phasor, the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor, and the grid-connected equivalent sequence impedance, the predicted positive-sequence voltage phasor and the predicted negative-sequence voltage phasor are obtained. The predicted execution positive sequence current phasor and the predicted execution negative sequence current phasor are combined into a three-phase predicted execution current phasor according to the symmetrical component relationship. The predicted execution phase current safety domain is constructed with the constraint that the amplitude of the three-phase predicted execution current phasor does not exceed the phase current limit allowed by the converter. Using the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor as voltage references, and the candidate positive-sequence current reference and the candidate negative-sequence current reference as optimization variables, the average active power is calculated. With the average active power equal to the currently latched active power retention value as an equality constraint, the sequence current dictionary order optimization is performed within the predicted execution phase current safety domain to obtain the optimal sequence current reference. When the minimum remaining limit of the positive sequence is greater than the positive sequence entry threshold, or the minimum remaining limit of the negative sequence is greater than the negative sequence entry threshold, or the predicted execution phase current safety domain is an empty set, the active power regulation degree of freedom is opened and active-reactive joint dictionary order optimization is performed to obtain the jointly optimized positive sequence current reference and negative sequence current reference. The positive-sequence current reference and negative-sequence current reference included in the optimal sequence current reference, or the positive-sequence current reference and negative-sequence current reference after joint optimization, are output as command values ​​for the positive-sequence current control loop and the negative-sequence current control loop, respectively.

[0008] Secondly, the present invention provides a grid-type wind turbine active-reactive power coordination support system, comprising: The transformation module is configured to collect the three-phase voltage and three-phase current at the grid connection point, and obtain the positive-sequence voltage d and q-axis components, positive-sequence current d and q-axis components, negative-sequence voltage d and q-axis components, and negative-sequence current d and q-axis components after positive-sequence and negative-sequence separation. All d and q-axis components are transformed to the same stationary complex phasor coordinate system to obtain the measured positive-sequence voltage phasor, measured positive-sequence current phasor, measured negative-sequence voltage phasor, and measured negative-sequence current phasor. The calculation module is configured to, based on candidate positive-sequence current references and candidate negative-sequence current references, and using the measured positive-sequence current phasors and the measured negative-sequence current phasors as current state quantities, recursively derive the predicted execution positive-sequence current phasors and the predicted execution negative-sequence current phasors through a first-order current closed-loop model, and obtain the predicted positive-sequence voltage phasors and the predicted negative-sequence voltage phasors based on the predicted execution positive-sequence current phasors and the predicted execution negative-sequence current phasors, the measured positive-sequence voltage phasors and the measured negative-sequence voltage phasors, and the grid-connected equivalent sequence impedance; The construction module is configured to synthesize the predicted execution positive sequence current phasor and the predicted execution negative sequence current phasor into a three-phase predicted execution current phasor according to the symmetrical component relationship, and construct the predicted execution phase current safety domain with the constraint that the amplitude of the three-phase predicted execution current phasor does not exceed the phase current limit allowed by the converter. The first optimization module is configured to use the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor as voltage references, the candidate positive-sequence current reference and the candidate negative-sequence current reference as optimization variables, calculate the average active power, and perform sequence current dictionary order optimization within the predicted execution phase current safety domain with the average active power equal to the currently latched active power retention value as an equality constraint to obtain the optimal sequence current reference. The second optimization module is configured to open the active power regulation degree of freedom and perform active-reactive joint dictionary order optimization when the minimum remaining limit of positive sequence is greater than the positive sequence entry threshold, or the minimum remaining limit of negative sequence is greater than the negative sequence entry threshold, or the predicted execution phase current safety domain is an empty set, so as to obtain the jointly optimized positive sequence current reference and negative sequence current reference. The output module is configured to output the positive-sequence current reference and negative-sequence current reference included in the optimal sequence current reference, or the jointly optimized positive-sequence current reference and negative-sequence current reference, as the command values ​​of the positive-sequence current control loop and the negative-sequence current control loop, respectively.

[0009] Thirdly, an electronic device is provided, comprising: at least one processor, and a memory communicatively connected to the at least one processor, wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the steps of the grid-connected wind turbine active-reactive power coordination support method according to any embodiment of the present invention.

[0010] Fourthly, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor performs the steps of the active-reactive power coordination support method for grid-connected wind turbines according to any embodiment of the present invention.

[0011] The active-reactive power coordination support method and system for grid-connected wind turbines disclosed in this application have the following beneficial effects: A unified safety boundary for phases A, B, and C is established using the predicted execution current, rather than the candidate reference without current closure. The predicted execution current formed after the candidate current reference is passed through a first-order current closure model truly reflects the actual phase current output by the converter in the next control cycle. Constructing the safety domain using the predicted execution current ensures that the optimization results are consistent with the actual converter response, avoiding the defect that independent limiting of sequence current cannot guarantee the safety of the actual three-phase current.

[0012] The lower limit of the positive sequence voltage is rewritten as a conservative affine constraint along the current positive sequence voltage direction, and a second-order cone amplitude upper limit is applied to the negative sequence voltage, so that both stages can be solved using second-order cone programming. Second-order cone programming has the advantages of high solution efficiency and guaranteed global optimality, and is suitable for real-time control scenarios.

[0013] The optimal reactive power result is obtained by maintaining the average active power first, and the active power degree of freedom is opened only when any sequence component is objectively infeasible, thereby reducing unnecessary active power reduction. In wind power scenarios, active power directly corresponds to power generation revenue, and premature reduction of active power will cause economic losses. This invention uses a dual-threshold triggering mechanism for reactive power infeasibility to reduce active power only when the positive or negative sequence voltage support cannot objectively meet the requirements, thus preserving the power generation capacity of wind turbine units to the greatest extent.

[0014] The positive and negative sequences are set with independent entry and exit thresholds, forming a hysteresis characteristic, which effectively suppresses frequent switching near the threshold. At the same time, the positive sequence low voltage and the negative sequence voltage imbalance retain independent physical thresholds and are not combined into a single weighted index, making the control objective clear and interpretable.

[0015] The dictionary order optimization is performed sequentially according to the priority of positive sequence voltage support, negative sequence voltage suppression, active power preservation, and current smoothing. The objectives and constraints at each level are all linear or second-order cone in form, which can be solved in real time using mature solvers, making it suitable for real-time execution environments embedded in converter controllers. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 A flowchart of a method for coordinated active and reactive power support of a grid-type wind turbine provided in an embodiment of the present invention; Figure 2 This is a structural block diagram of a grid-type wind turbine active-reactive power coordination support system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figure 1 The diagram shows a flowchart of a method for coordinated active and reactive power support of a grid-type wind turbine according to this application.

[0020] like Figure 1 As shown, the active and reactive power coordination support method for grid-connected wind turbines specifically includes the following steps: Step S101: Collect the three-phase voltage and three-phase current at the grid connection point, and obtain the positive-sequence voltage d and q-axis components, positive-sequence current d and q-axis components, negative-sequence voltage d and q-axis components, and negative-sequence current d and q-axis components by positive-sequence and negative-sequence separation. Transform all d and q-axis components to the same stationary complex phasor coordinate to obtain the measured positive-sequence voltage phasor, measured positive-sequence current phasor, measured negative-sequence voltage phasor, and measured negative-sequence current phasor.

[0021] In this step, the three-phase instantaneous voltage and three-phase instantaneous current at the grid connection point are collected. The three-phase instantaneous voltage and three-phase instantaneous current are transformed from three-phase stationary coordinates to two-phase stationary coordinates through Clark transformation, respectively, to obtain the voltage α and β components and current α and β components in the two-phase stationary coordinates. The voltage α and β components and current α and β components in the two-phase stationary coordinates are used as the inputs for the positive sequence and negative sequence separation. The voltage α and β components under the two-phase stationary coordinates are input into the positive sequence synchronous rotating coordinate transformation. The positive sequence synchronous rotating coordinate transformation takes the positive sequence synchronous angle as the rotation angle and outputs the positive sequence voltage d and q axis components. The current α and β components under the two-phase stationary coordinates are input into the positive sequence synchronous rotating coordinate transformation and output the positive sequence current d and q axis components. The voltage α and β components under the two-phase stationary coordinates are input into the negative sequence synchronous rotating coordinate transformation. The negative sequence synchronous rotating coordinate transformation takes the negative sequence synchronous angle as the rotation angle and outputs the negative sequence voltage d and q axis components. The current α and β components under the two-phase stationary coordinates are input into the negative sequence synchronous rotating coordinate transformation and output the negative sequence current d and q axis components.

[0022] Furthermore, for the positive-sequence components, the d-axis and q-axis components of the positive-sequence voltage are multiplied by a positive rotation factor. The measured positive-sequence voltage phasor is obtained, and the d-axis and q-axis components of the positive-sequence current are multiplied by the positive rotation factor. The measured positive-sequence current phasor is obtained, and its expression is: , , In the formula, The measured positive-sequence voltage phasor for the k-th period. The positive sequence voltage d-axis component of the k-th period is... The positive sequence voltage q-axis component of the k-th period. Let be the electrical angle of the positive-sequence synchronous rotating coordinates relative to the stationary coordinates in the k-th period. The imaginary unit, The d-axis component of the positive sequence current in the k-th period. Let q be the positive sequence current q-axis component of the k-th period. The measured positive sequence current phasor for the k-th period; For the negative sequence component, multiply the negative sequence voltage d-axis and q-axis components by the reverse rotation factor. The measured negative sequence voltage phasor is obtained, and the d-axis and q-axis components of the negative sequence current are multiplied by the reverse rotation factor. The measured negative sequence current phasor is obtained, and its expression is: , , In the formula, This is the measured negative sequence voltage phasor for the k-th period. The d-axis component of the negative sequence voltage in the k-th period. This represents the q-axis component of the negative sequence voltage in the k-th period. The measured negative sequence current phasor for the k-th period. The d-axis component of the negative sequence current in the k-th period. This represents the q-axis component of the negative sequence current in the k-th period.

[0023] Step S102: Based on the candidate positive-sequence current reference and the candidate negative-sequence current reference, and using the measured positive-sequence current phasor and the measured negative-sequence current phasor as the current state variables, the predicted execution positive-sequence current phasor and the predicted execution negative-sequence current phasor are recursively obtained through a first-order current closed-loop model. Based on the predicted execution positive-sequence current phasor and the predicted execution negative-sequence current phasor, the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor, and the grid-connected equivalent sequence impedance, the predicted positive-sequence voltage phasor and the predicted negative-sequence voltage phasor are obtained.

[0024] In this step, for the positive sequence component, the measured positive sequence current phasor is used as the current state quantity, and the candidate positive sequence current reference is used as the input quantity. The predicted execution positive sequence current phasor is obtained by recursion through a first-order current closed-loop model. For the negative sequence component, using the measured negative sequence current phasor as the current state quantity and the candidate negative sequence current reference as the input quantity, the predicted execution negative sequence current phasor is recursively obtained through the first-order current closed-loop model, wherein the expression of the first-order current closed-loop model is: , , , In the formula, This is an ordinal component index, where the superscript "+" indicates positive order and the superscript "−" indicates negative order. For order components The current closed-loop one-step response coefficient, For order components The current closed-loop equivalent angular bandwidth. To control the cycle, It is a natural constant. For the real sequencing current phasor of the k-th period, when When taking the ascending order To measure the positive sequence current phasor, when When taking the negative order The measured negative sequence current phasor is referred to here. Let k be the candidate sequence current reference phasor for the k-th period. When taking the ascending order As the candidate positive sequence current reference, when When taking the negative order This serves as a reference for the candidate negative sequence current. To predict the sequence current phasor for the (k+1)th cycle based on the information from the kth cycle, when When taking the ascending order To predict the execution of the positive-sequence current phasor, when When taking the negative order To predict the execution of negative sequence current phasors.

[0025] Furthermore, for the positive sequence component, the measured positive sequence voltage phasor and the predicted positive sequence current phasor are used as inputs, and the positive sequence grid-connected equivalent impedance is combined to obtain the predicted positive sequence voltage phasor through the voltage prediction model. For the negative sequence component, using the measured negative sequence voltage phasor and the predicted negative sequence current phasor as inputs, and combining the negative sequence grid-connected equivalent impedance, the predicted negative sequence voltage phasor is obtained through a voltage prediction model. The expression of the voltage prediction model is as follows: , , In the formula, This is an ordinal component index, where the superscript "+" indicates positive order and the superscript "−" indicates negative order. For the k-th periodic sequence component The equivalent grid voltage estimation phasor, For the measured grid-connected point sequence voltage phasor of the k-th cycle, when When taking the ascending order To measure the positive-sequence voltage phasor, when When taking the negative order To measure the negative sequence voltage phasor, Sequence component seen at the grid connection point The equivalent impedance, Let be the real sequencing current phasor of the k-th cycle. For the sequence voltage phasor of the grid connection point in the (k+1)th period predicted based on the information of the kth period, when When taking the ascending order To predict the positive-sequence voltage phasor, when When taking the negative order To predict negative sequence voltage phasors, To predict the sequence current phasor for the (k+1)th cycle based on the information from the kth cycle, when When taking the ascending order To predict the execution of the positive-sequence current phasor, when When taking the negative order To predict the execution of negative sequence current phasors.

[0026] Step S103: Combine the predicted execution positive sequence current phasor and the predicted execution negative sequence current phasor into a three-phase predicted execution current phasor according to the symmetrical component relationship. Construct the predicted execution phase current safety domain with the constraint that the amplitude of the three-phase predicted execution current phasor does not exceed the phase current limit allowed by the converter.

[0027] In this step, the predicted execution positive-sequence current phasor and the predicted execution negative-sequence current phasor are multiplied by their respective rotation factors and then added together to obtain the three-phase predicted execution current phasor, expressed as: , , , , In the formula, , , These are the predicted execution current phasors for phase A, phase B, and phase C, respectively. To predict the execution positive sequence current phasor, To predict the execution of negative sequence current phasors, The rotation factor of the symmetric component. It is a natural constant. The imaginary unit; With the constraint that the amplitudes of the predicted execution current phasors of phase A, phase B, and phase C all do not exceed the allowable phase current limit of the converter, the safety domain of the predicted execution phase current is constructed, and its expression is: , In the formula, For the k-th period, the set of safe and feasible phase current predictions is given. Let p be the amplitude of the p-th phase in the three-phase predictive execution current phasor. This represents the upper limit of the effective value of the single-phase current allowed by the converter. This is the phase index for phases A, B, and C.

[0028] Step S104: Using the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor as voltage references, and the candidate positive-sequence current reference and the candidate negative-sequence current reference as optimization variables, calculate the average active power, and with the average active power equal to the currently latched active power retention value as an equality constraint, perform sequence current dictionary order optimization within the predicted execution phase current safety domain to obtain the optimal sequence current reference.

[0029] In this step, using the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor as voltage references, and the candidate positive-sequence current reference and the candidate negative-sequence current reference as optimization variables, the average active power is calculated, expressed as: , In the formula, The value represents the average active power. A positive value indicates that the grid-side converter injects active power into the grid, while a negative value indicates that it absorbs active power from the grid. For the measured positive sequence voltage phasor, As a candidate positive sequence current reference To measure the negative sequence voltage phasor, As a candidate negative sequence current reference, This is a complex conjugate operation. This is for operations involving the real part of complex numbers; The average active power is equal to the currently latched active power retention value. As an equality constraint, minimizing the remaining positive-sequence voltage exceedance is the first priority, minimizing the remaining negative-sequence voltage exceedance is the second priority, and minimizing the sequence current change is the third priority. Within the predicted phase current safety domain, sequence current dictionary order optimization is performed to obtain the optimal sequence current reference. The decision vector for the sequence current dictionary order optimization is: , In the formula, The decision vector for optimizing the order of the current dictionary is given. and These are the real and imaginary parts of the candidate positive-sequence current reference, respectively. and These are the real and imaginary parts of the candidate negative sequence current reference, respectively. The positive-sequence voltage remaining limit is a non-negative relaxation variable. The remaining excess of negative sequence voltage is a non-negative relaxation variable. The second-order cone upper bound auxiliary variable is used for the sequence current reference change. It is the transpose symbol; The common feasible set of ordered current dictionary order optimization Includes: the first-order current closed-loop model and sequence voltage prediction equation, the prediction execution phase current safety domain, positive sequence voltage constraints and negative sequence voltage constraints, the equation constraint that the average active power equals the active power retention value, rated capacity constraints, second-order cone constraints on sequence current change, and non-negative relaxation variable constraints. The order current dictionary optimization is performed sequentially in the following three layers: The first layer, in the public feasible set The expression for minimizing the residual positive-sequence voltage limit is: , In the formula, This represents the minimum remaining threshold in the positive order, i.e., the optimal value obtained from the first level of optimization. Indicates in the common feasible set Inner decision vector Take the objective function Minimal operation; The second layer involves locking the optimal value from the first layer, and then considering the common feasible set. The expression for minimizing the residual negative sequence voltage limit is: , In the formula, This represents the minimum residual threshold in the negative order, i.e., the optimal value obtained from the second level of optimization. The non-negative lexicographical order locking tolerance for the positive-order optimal value is a preset constant. The locking constraint for the first-level optimal value means that the remaining positive-sequence voltage limit during the second-level optimization must not exceed the first-level optimal value plus the tolerance. The third layer, after locking the optimal values ​​of the first and second layers, is based on the common feasible set. The expression for the minimum sequence current change is: , In the formula, This is the decision vector corresponding to the optimal sequence current reference, i.e., the optimal solution obtained from the third layer of optimization. This is a locking constraint for the second-level optimal value. The non-negative lexicographical order locking tolerance for the negative-order optimal value is a preset constant. To make the objective function Decision vector when the minimum value is obtained The value of .

[0030] Step S105: When the minimum remaining limit of the positive sequence is greater than the positive sequence entry threshold, or the minimum remaining limit of the negative sequence is greater than the negative sequence entry threshold, or the predicted execution phase current safety domain is an empty set, the active power regulation degree of freedom is opened and active-reactive joint dictionary order optimization is performed to obtain the jointly optimized positive sequence current reference and negative sequence current reference.

[0031] In this step, a threshold value is set for the minimum positive-order residual exceeding the limit to enter the joint optimization stage. The threshold value for exiting the joint optimization phase with the minimum remaining quantity in the ascending order. Threshold value for entering the joint optimization stage with the minimum negative residue threshold. The threshold value for exiting the joint optimization phase with the minimum negative remainder. ; When the minimum remaining quantity in the ascending order exceeds the limit Greater than the positive sequence entry threshold Or the minimum residual quantity in negative order Greater than the negative order entry threshold , or the aforementioned public feasible set When the set is empty, the active power adjustment degree of freedom is opened and active power-reactive power joint lexicographical order optimization is performed. The decision vector for the active power-reactive power joint lexicographical order optimization is: , In the formula, The decision vector for optimizing the joint lexicographical order of active and reactive power. This is the non-negative active power reduction relative to the active power retention value. , The optimized average active power, This represents the active power retention value latched before optimization in the k-th control cycle. and These are the real and imaginary parts of the candidate positive-sequence current reference, respectively. and These are the real and imaginary parts of the candidate negative sequence current reference, respectively. The positive-sequence voltage remaining limit is a non-negative relaxation variable. The remaining excess of negative sequence voltage is a non-negative relaxation variable. The second-order cone upper bound auxiliary variable is used for the sequence current reference change. It is the transpose symbol; The common feasible set of active-reactive joint lexicographical order optimization It includes: the first-order current closed-loop model and sequence voltage prediction equation, the prediction execution phase current safety domain, positive-sequence voltage constraints and negative-sequence voltage constraints, rated capacity constraints, second-order cone constraints for sequence current change, average active power boundary constraints, and non-negative relaxation variable constraints. The average active power boundary constraints are: , In the formula, The lower limit of the grid-side average active power in the k-th cycle is determined by the allowable energy absorption of the DC bus. The active-reactive joint lexical order optimization is performed sequentially at the following four levels: The first layer, in the public feasible set The expression for minimizing the residual positive-sequence voltage limit is: , In the formula, To jointly optimize the optimal value of the positive-order minimum residual limit obtained in the first layer. Indicates in the common feasible set Inner decision vector Take the objective function Minimal operation; The second layer involves locking the optimal value from the first layer, and then considering the common feasible set. The expression for minimizing the residual negative sequence voltage limit is: , In the formula, To jointly optimize the optimal value of the negative-order minimum residual threshold obtained in the second layer. Locking constraints for the first-level optimal value; The third layer, after locking the optimal values ​​of the first and second layers, is based on the common feasible set. The expression for minimizing the active power reduction is: , In the formula, To jointly optimize the minimum active power reduction obtained from the third layer, Locking constraints for the second-level optimal value; In the fourth layer, after locking the optimal values ​​of the first, second, and third layers, the values ​​are then considered in the common feasible set. The expression for the minimum sequence current change is: , In the formula, These are the decision vectors corresponding to the jointly optimized positive-sequence current reference and negative-sequence current reference. This is a locking constraint for the third-level optimal value. The non-negative lexicographical order locking tolerance for the optimal value of active power reduction is a preset constant. This indicates that the objective function Decision vector when the minimum value is obtained The value of ; When the positive order minimum remaining limit is exceeded and the negative order minimum remaining limit quantity Simultaneously satisfy and And continuously preset the quantity During each control cycle, the active power regulation degree of freedom is closed, and the control strategy is switched from the active-reactive joint dictionary order optimization back to the sequence current dictionary order optimization, wherein... It is a preset positive integer representing the number of continuous control cycles required to exit the joint phase.

[0032] Step S106: The positive-sequence current reference and negative-sequence current reference included in the optimal sequence current reference, or the positive-sequence current reference and negative-sequence current reference after joint optimization, are output as command values ​​for the positive-sequence current control loop and the negative-sequence current control loop, respectively.

[0033] In one specific embodiment, suppose that an asymmetrical grid voltage drop occurs at the grid-side converter of a certain grid-connected wind turbine, and the effective value of the positive sequence voltage at the grid connection point is... Negative sequence voltage Current measured positive sequence voltage Negative sequence voltage Current active power retention value .

[0034] The predicted execution phase current safety domain constructed in step S103 limits the feasible range of candidate sequence current references. Step S104 solves for sequence current dictionary order optimization while maintaining an active power of 0.9 pu. If a positive sequence voltage can be found within the feasible domain... and negative sequence voltage If all solutions are zero, then the optimal values ​​for both the first and second layers are zero, indicating that voltage support requirements can be met solely through reactive power regulation, without the need to reduce active power. In this case, the optimal sequence current reference is output, the converter maintains constant active power, and only the reactive power output is adjusted.

[0035] like This indicates that the positive sequence voltage lower limit requirement cannot be met while maintaining constant active power, triggering joint active-reactive power dictionary optimization. Joint optimization releases the active power regulation degree of freedom. The search space is used to find the minimum active power reduction that makes the positive sequence voltage constraint hold. The converter will reduce active power from 0.9 pu to 0.85 pu, while maximizing reactive power output to support positive sequence voltage. After the grid voltage recovers, if the minimum remaining positive and negative sequence current exceeds the limit for N consecutive cycles, the system will switch back-sequence current dictionary optimization, and active power will gradually recover.

[0036] In summary, the method of this application collects the three-phase voltage and current at the grid connection point, extracts the positive and negative sequence components and transforms them to the same static complex phasor coordinates. Using the candidate sequence current reference as input and the actual sequence current as the state variable, it predicts the execution sequence current and the grid connection point sequence voltage through a first-order current closed-loop model and the equivalent sequence impedance of the grid connection. The predicted execution positive and negative sequence currents are synthesized into three-phase currents according to the symmetrical component relationship. A phase current safety domain is constructed with the condition that the amplitude of each phase current does not exceed the allowable limit of the converter. Using affine lower limit constraints along the current positive sequence voltage direction and upper limit constraints for negative sequence voltage amplitude, sequence current dictionary optimization is performed while maintaining the average active power constant to obtain the minimum residual over-limit quantities for positive and negative sequences. When any sequence minimum residual over-limit quantity exceeds the corresponding entry threshold or the common feasible set is empty, the active power regulation degree of freedom is opened and active-reactive power joint dictionary optimization is performed. A safe sequence current reference is output to the positive and negative sequence current control loops. The optimization problem is maintained in a second-order cone form, taking into account overcurrent constraints for each phase, positive sequence voltage support, and negative sequence voltage suppression.

[0037] Please see Figure 2 The diagram shows a structural block diagram of a grid-type wind turbine active-reactive power coordination support system according to this application.

[0038] like Figure 2 As shown, the active-reactive power coordination support system 200 for grid-type wind turbines includes a conversion module 210, a calculation module 220, a construction module 230, a first optimization module 240, a second optimization module 250, and an output module 260.

[0039] The transformation module 210 is configured to acquire the three-phase voltage and three-phase current at the grid connection point, separate the positive-sequence and negative-sequence voltage d and q-axis components, positive-sequence current d and q-axis components, negative-sequence voltage d and q-axis components, and negative-sequence current d and q-axis components, and transform all d and q-axis components to the same stationary complex phasor coordinate system to obtain the measured positive-sequence voltage phasor, measured positive-sequence current phasor, measured negative-sequence voltage phasor, and measured negative-sequence current phasor. The calculation module 220 is configured to, based on candidate positive-sequence current references and candidate negative-sequence current references, calculate the measured positive-sequence current phasor and the measured negative-sequence current phasor. The negative-sequence current phasor is the current state quantity. The predicted positive-sequence current phasor and the predicted negative-sequence current phasor are recursively obtained through a first-order current closed-loop model. Based on the predicted positive-sequence current phasor, the predicted negative-sequence current phasor, the measured positive-sequence voltage phasor, the measured negative-sequence voltage phasor, and the grid-connected equivalent sequence impedance, the predicted positive-sequence voltage phasor and the predicted negative-sequence voltage phasor are obtained. The construction module 230 is configured to synthesize the predicted positive-sequence current phasor and the predicted negative-sequence current phasor into a three-phase predicted execution current phasor according to a symmetrical component relationship, using the three-phase predicted execution current... The constraint condition is that the amplitude of the current phasor does not exceed the allowable phase current limit of the converter, thus constructing a predictive execution phase current safety domain; the first optimization module 240 is configured to use the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor as voltage references, and the candidate positive-sequence current reference and the candidate negative-sequence current reference as optimization variables to calculate the average active power, and with the average active power equal to the currently latched active power retention value as an equality constraint, perform sequence current dictionary order optimization within the predictive execution phase current safety domain to obtain the optimal sequence current reference; the second optimization module 250 is configured to when When the minimum remaining threshold for positive sequence exceeds the positive sequence entry threshold, or the minimum remaining threshold for negative sequence exceeds the negative sequence entry threshold, or when the predicted execution phase current safety domain is an empty set, the active power regulation degree of freedom is opened and active-reactive joint dictionary order optimization is performed to obtain the jointly optimized positive sequence current reference and negative sequence current reference; the output module 260 is configured to output the positive sequence current reference and negative sequence current reference contained in the optimal sequence current reference, or the jointly optimized positive sequence current reference and negative sequence current reference, as the command values ​​of the positive sequence current control loop and the negative sequence current control loop, respectively.

[0040] It should be understood that Figure 2 The modules and references described in the document Figure 1 The steps described in the text correspond to those in the method described above. Therefore, the operations, features, and corresponding technical effects described above also apply to the method described in the text. Figure 2 The various modules in the document will not be described in detail here.

[0041] In other embodiments, the present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein when the program instructions are executed by a processor, the processor performs the active-reactive power coordination support method for grid-connected wind turbines in any of the above method embodiments. In one embodiment, the computer-readable storage medium of the present invention stores computer-executable instructions, which are configured as follows: The three-phase voltage and three-phase current at the grid connection point are collected. After positive-sequence and negative-sequence separation, the positive-sequence voltage d-axis and q-axis components, positive-sequence current d-axis and q-axis components, negative-sequence voltage d-axis and q-axis components, and negative-sequence current d-axis and q-axis components are obtained. All d-axis and q-axis components are transformed to the same stationary complex phasor coordinate system to obtain the measured positive-sequence voltage phasor, measured positive-sequence current phasor, measured negative-sequence voltage phasor, and measured negative-sequence current phasor. Based on the candidate positive-sequence current reference and the candidate negative-sequence current reference, and using the measured positive-sequence current phasor and the measured negative-sequence current phasor as the current state variables, the predicted execution positive-sequence current phasor and the predicted execution negative-sequence current phasor are recursively obtained through a first-order current closed-loop model. Based on the predicted execution positive-sequence current phasor and the predicted execution negative-sequence current phasor, the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor, and the grid-connected equivalent sequence impedance, the predicted positive-sequence voltage phasor and the predicted negative-sequence voltage phasor are obtained. The predicted execution positive sequence current phasor and the predicted execution negative sequence current phasor are combined into a three-phase predicted execution current phasor according to the symmetrical component relationship. The predicted execution phase current safety domain is constructed with the constraint that the amplitude of the three-phase predicted execution current phasor does not exceed the phase current limit allowed by the converter. Using the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor as voltage references, and the candidate positive-sequence current reference and the candidate negative-sequence current reference as optimization variables, the average active power is calculated. With the average active power equal to the currently latched active power retention value as an equality constraint, the sequence current dictionary order optimization is performed within the predicted execution phase current safety domain to obtain the optimal sequence current reference. When the minimum remaining limit of the positive sequence is greater than the positive sequence entry threshold, or the minimum remaining limit of the negative sequence is greater than the negative sequence entry threshold, or the predicted execution phase current safety domain is an empty set, the active power regulation degree of freedom is opened and active-reactive joint dictionary order optimization is performed to obtain the jointly optimized positive sequence current reference and negative sequence current reference. The positive-sequence current reference and negative-sequence current reference included in the optimal sequence current reference, or the positive-sequence current reference and negative-sequence current reference after joint optimization, are output as command values ​​for the positive-sequence current control loop and the negative-sequence current control loop, respectively.

[0042] Computer-readable storage media may include a stored program area and a stored data area, wherein the stored program area may store an operating system and an application program required for at least one function; the stored data area may store data created based on the use of the grid-connected wind turbine active-reactive power coordination support system, etc. Furthermore, the computer-readable storage medium may include high-speed random access memory, and may also include memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, the computer-readable storage medium may optionally include memory remotely located relative to a processor, and these remote memories may be connected to the grid-connected wind turbine active-reactive power coordination support system via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0043] Figure 3 This is a schematic diagram of the structure of the electronic device provided in the embodiment of the present invention, such as... Figure 3 As shown, the device includes a processor 310 and a memory 320. The electronic device may also include an input device 330 and an output device 340. The processor 310, memory 320, input device 330, and output device 340 can be connected via a bus or other means. Figure 3 Taking a bus connection as an example, the memory 320 is the computer-readable storage medium described above. The processor 310 executes various server functions and data processing by running non-volatile software programs, instructions, and modules stored in the memory 320, thereby implementing the active-reactive power coordination support method for grid-connected wind turbines described in the above embodiment. The input device 330 can receive input digital or character information and generate key signal inputs related to user settings and function control of the grid-connected wind turbine active-reactive power coordination support system. The output device 340 may include a display screen or other display device.

[0044] The aforementioned electronic device can execute the method provided in the embodiments of the present invention, and has the corresponding functional modules and beneficial effects for executing the method. Technical details not described in detail in this embodiment can be found in the method provided in the embodiments of the present invention.

[0045] In one implementation, the above-described electronic device is applied to a grid-connected wind turbine active-reactive power coordination support system for a client, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to: The three-phase voltage and three-phase current at the grid connection point are collected. After positive-sequence and negative-sequence separation, the positive-sequence voltage d-axis and q-axis components, positive-sequence current d-axis and q-axis components, negative-sequence voltage d-axis and q-axis components, and negative-sequence current d-axis and q-axis components are obtained. All d-axis and q-axis components are transformed to the same stationary complex phasor coordinate system to obtain the measured positive-sequence voltage phasor, measured positive-sequence current phasor, measured negative-sequence voltage phasor, and measured negative-sequence current phasor. Based on the candidate positive-sequence current reference and the candidate negative-sequence current reference, and using the measured positive-sequence current phasor and the measured negative-sequence current phasor as the current state variables, the predicted execution positive-sequence current phasor and the predicted execution negative-sequence current phasor are recursively obtained through a first-order current closed-loop model. Based on the predicted execution positive-sequence current phasor and the predicted execution negative-sequence current phasor, the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor, and the grid-connected equivalent sequence impedance, the predicted positive-sequence voltage phasor and the predicted negative-sequence voltage phasor are obtained. The predicted execution positive sequence current phasor and the predicted execution negative sequence current phasor are combined into a three-phase predicted execution current phasor according to the symmetrical component relationship. The predicted execution phase current safety domain is constructed with the constraint that the amplitude of the three-phase predicted execution current phasor does not exceed the phase current limit allowed by the converter. Using the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor as voltage references, and the candidate positive-sequence current reference and the candidate negative-sequence current reference as optimization variables, the average active power is calculated. With the average active power equal to the currently latched active power retention value as an equality constraint, the sequence current dictionary order optimization is performed within the predicted execution phase current safety domain to obtain the optimal sequence current reference. When the minimum remaining limit of the positive sequence is greater than the positive sequence entry threshold, or the minimum remaining limit of the negative sequence is greater than the negative sequence entry threshold, or the predicted execution phase current safety domain is an empty set, the active power regulation degree of freedom is opened and active-reactive joint dictionary order optimization is performed to obtain the jointly optimized positive sequence current reference and negative sequence current reference. The positive-sequence current reference and negative-sequence current reference included in the optimal sequence current reference, or the positive-sequence current reference and negative-sequence current reference after joint optimization, are output as command values ​​for the positive-sequence current control loop and the negative-sequence current control loop, respectively.

[0046] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of various embodiments or some parts of embodiments.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for coordinated active and reactive power support of a grid-connected wind turbine generator, characterized in that, include: The three-phase voltage and three-phase current at the grid connection point are collected. After positive-sequence and negative-sequence separation, the positive-sequence voltage d-axis and q-axis components, positive-sequence current d-axis and q-axis components, negative-sequence voltage d-axis and q-axis components, and negative-sequence current d-axis and q-axis components are obtained. All d-axis and q-axis components are transformed to the same stationary complex phasor coordinate system to obtain the measured positive-sequence voltage phasor, measured positive-sequence current phasor, measured negative-sequence voltage phasor, and measured negative-sequence current phasor. Based on the candidate positive-sequence current reference and the candidate negative-sequence current reference, and using the measured positive-sequence current phasor and the measured negative-sequence current phasor as the current state variables, the predicted execution positive-sequence current phasor and the predicted execution negative-sequence current phasor are recursively obtained through a first-order current closed-loop model. Based on the predicted execution positive-sequence current phasor and the predicted execution negative-sequence current phasor, the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor, and the grid-connected equivalent sequence impedance, the predicted positive-sequence voltage phasor and the predicted negative-sequence voltage phasor are obtained. The predicted execution positive sequence current phasor and the predicted execution negative sequence current phasor are combined into a three-phase predicted execution current phasor according to the symmetrical component relationship. The predicted execution phase current safety domain is constructed with the constraint that the amplitude of the three-phase predicted execution current phasor does not exceed the phase current limit allowed by the converter. Using the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor as voltage references, and the candidate positive-sequence current reference and the candidate negative-sequence current reference as optimization variables, the average active power is calculated. With the average active power equal to the currently latched active power retention value as an equality constraint, the sequence current dictionary order optimization is performed within the predicted execution phase current safety domain to obtain the optimal sequence current reference. When the minimum remaining limit of the positive sequence is greater than the positive sequence entry threshold, or the minimum remaining limit of the negative sequence is greater than the negative sequence entry threshold, or the predicted execution phase current safety domain is an empty set, the active power regulation degree of freedom is opened and active-reactive joint dictionary order optimization is performed to obtain the jointly optimized positive sequence current reference and negative sequence current reference. The positive-sequence current reference and negative-sequence current reference included in the optimal sequence current reference, or the positive-sequence current reference and negative-sequence current reference after joint optimization, are output as command values ​​for the positive-sequence current control loop and the negative-sequence current control loop, respectively.

2. The active and reactive power coordinated support method for a grid-type wind turbine generator according to claim 1, characterized in that, The three-phase voltage and three-phase current of the grid-connected point are collected and separated into positive-sequence and negative-sequence components to obtain the positive-sequence voltage d and q-axis components, the positive-sequence current d and q-axis components, the negative-sequence voltage d and q-axis components, and the negative-sequence current d and q-axis components, including: The three-phase instantaneous voltage and three-phase instantaneous current at the grid connection point are collected. The three-phase instantaneous voltage and three-phase instantaneous current are transformed from three-phase stationary coordinates to two-phase stationary coordinates through Clark transformation, respectively, to obtain the voltage α and β components and current α and β components in the two-phase stationary coordinates. The voltage α and β components and current α and β components in the two-phase stationary coordinates are used as the inputs for the positive sequence and negative sequence separation. The voltage α and β components under the two-phase stationary coordinates are input into the positive sequence synchronous rotating coordinate transformation. The positive sequence synchronous rotating coordinate transformation takes the positive sequence synchronous angle as the rotation angle and outputs the positive sequence voltage d and q axis components. The current α and β components under the two-phase stationary coordinates are input into the positive sequence synchronous rotating coordinate transformation and output the positive sequence current d and q axis components. The voltage α and β components under the two-phase stationary coordinates are input into the negative sequence synchronous rotating coordinate transformation. The negative sequence synchronous rotating coordinate transformation takes the negative sequence synchronous angle as the rotation angle and outputs the negative sequence voltage d and q axis components. The current α and β components under the two-phase stationary coordinates are input into the negative sequence synchronous rotating coordinate transformation and output the negative sequence current d and q axis components.

3. The active and reactive power coordinated support method for a grid-type wind turbine generator according to claim 1, characterized in that, The process of transforming all d-axis and q-axis components to the same stationary complex phasor coordinates to obtain the measured positive-sequence voltage phasor, measured positive-sequence current phasor, measured negative-sequence voltage phasor, and measured negative-sequence current phasor includes: For the positive sequence components, multiply the d-axis and q-axis components of the positive sequence voltage by a positive rotation factor. The measured positive-sequence voltage phasor is obtained, and the d-axis and q-axis components of the positive-sequence current are multiplied by the positive rotation factor. The measured positive-sequence current phasor is obtained, and its expression is: ， ， In the formula, The measured positive-sequence voltage phasor for the k-th period. The positive sequence voltage d-axis component of the k-th period is... The positive sequence voltage q-axis component of the k-th period. Let be the electrical angle of the positive-sequence synchronous rotating coordinates relative to the stationary coordinates in the k-th period. The imaginary unit, Let d be the positive sequence current of the k-th period. Let q be the positive sequence current q-axis component of the k-th period. The measured positive sequence current phasor for the k-th period; For the negative sequence component, multiply the negative sequence voltage d-axis and q-axis components by the reverse rotation factor. The measured negative sequence voltage phasor is obtained, and the d-axis and q-axis components of the negative sequence current are multiplied by the reverse rotation factor. The measured negative sequence current phasor is obtained, and its expression is: ， ， In the formula, The measured negative sequence voltage phasor for the k-th period. The d-axis component of the negative sequence voltage in the k-th period. This represents the q-axis component of the negative sequence voltage in the k-th period. The measured negative sequence current phasor for the k-th period is given. The d-axis component of the negative sequence current in the k-th period. This represents the q-axis component of the negative sequence current in the k-th period.

4. The active and reactive power coordinated support method for a grid-type wind turbine generator according to claim 1, characterized in that, The step of recursively obtaining the predicted positive-sequence current phasor and the predicted negative-sequence current phasor through a first-order current closed-loop model, based on candidate positive-sequence current references and candidate negative-sequence current references, and using the measured positive-sequence current phasor and the measured negative-sequence current phasor as current state quantities, includes: For the positive sequence component, the measured positive sequence current phasor is used as the current state quantity, and the candidate positive sequence current reference is used as the input quantity. The predicted execution positive sequence current phasor is obtained by recursion through a first-order current closed-loop model. For the negative sequence component, using the measured negative sequence current phasor as the current state quantity and the candidate negative sequence current reference as the input quantity, the predicted execution negative sequence current phasor is obtained recursively through the first-order current closed-loop model, wherein the expression of the first-order current closed-loop model is: ， ， ， In the formula, This is an ordinal component index, where the superscript "+" indicates positive order and the superscript "−" indicates negative order. For order components The current closed-loop one-step response coefficient, For order components The current closed-loop equivalent angular bandwidth. To control the cycle, It is a natural constant. For the real sequencing current phasor of the k-th period, when When taking the ascending order To measure the positive sequence current phasor, when When taking the negative order The measured negative sequence current phasor is referred to here. Let k be the candidate sequence current reference phasor for the k-th period. When taking the ascending order As the candidate positive sequence current reference, when When taking the negative order This serves as a reference for the candidate negative sequence current. To predict the sequence current phasor for the (k+1)th cycle based on the information from the kth cycle, when When taking the ascending order To predict the execution of the positive-sequence current phasor, when When taking the negative order To predict the execution of negative sequence current phasors.

5. The active and reactive power coordinated support method for a grid-type wind turbine generator according to claim 1, characterized in that, The process of obtaining the predicted positive-sequence voltage phasor and the predicted negative-sequence voltage phasor based on the predicted positive-sequence current phasor and the predicted negative-sequence current phasor, the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor, and the grid-connected equivalent sequence impedance includes: For the positive sequence component, the measured positive sequence voltage phasor and the predicted positive sequence current phasor are used as inputs, and the predicted positive sequence grid-connected equivalent impedance is combined with the voltage prediction model to obtain the predicted positive sequence voltage phasor. For the negative sequence component, using the measured negative sequence voltage phasor and the predicted negative sequence current phasor as inputs, and combining the negative sequence grid-connected equivalent impedance, the predicted negative sequence voltage phasor is obtained through a voltage prediction model. The expression of the voltage prediction model is as follows: ， ， In the formula, This is an ordinal component index, where the superscript "+" indicates positive order and the superscript "−" indicates negative order. For the k-th periodic sequence component The equivalent grid voltage estimation phasor, For the measured grid-connected point sequence voltage phasor of the k-th cycle, when When taking the ascending order To measure the positive-sequence voltage phasor, when When taking the negative order To measure the negative sequence voltage phasor, Sequence component seen at the grid connection point The equivalent impedance, Let be the real sequencing current phasor of the k-th cycle. For the sequence voltage phasor of the grid connection point in the (k+1)th period predicted based on the information of the kth period, when When taking the ascending order To predict the positive-sequence voltage phasor, when When taking the negative order To predict negative sequence voltage phasors, To predict the sequence current phasor for the (k+1)th cycle based on the information from the kth cycle, when When taking the ascending order To predict the execution of the positive-sequence current phasor, when When taking the negative order To predict the execution of negative sequence current phasors.

6. The active and reactive power coordinated support method for a grid-type wind turbine generator according to claim 1, characterized in that, The step of combining the predicted positive-sequence current phasor and the predicted negative-sequence current phasor into a three-phase predicted current phasor according to a symmetrical component relationship, and constructing the predicted phase current safety domain with the constraint that the amplitude of each of the three-phase predicted current phasors does not exceed the allowable phase current limit of the converter, includes: Multiply the predicted positive-sequence current phasor and the predicted negative-sequence current phasor by their respective rotation factors and then add them together to obtain the three-phase predicted current phasor, expressed as: ， ， ， ， In the formula, , , These are the predicted execution current phasors for phase A, phase B, and phase C, respectively. To predict the execution positive sequence current phasor, To predict the execution of negative sequence current phasors, The rotation factor of the symmetric component. It is a natural constant. The imaginary unit; With the constraint that the amplitudes of the predicted execution current phasors of phase A, phase B, and phase C all do not exceed the allowable phase current limit of the converter, the safety domain of the predicted execution phase current is constructed, and its expression is: ， In the formula, For the k-th period, the set of safe and feasible phase current predictions is given. Let p be the amplitude of the p-th phase in the three-phase predictive execution current phasor. This represents the upper limit of the effective value of the single-phase current allowed by the converter. This is the phase index for phases A, B, and C.

7. The active and reactive power coordinated support method for a grid-type wind turbine generator according to claim 1, characterized in that, The process involves using measured positive-sequence voltage phasors and measured negative-sequence voltage phasors as voltage references, and candidate positive-sequence current references and candidate negative-sequence current references as optimization variables. The average active power is calculated, and the average active power is constrained by the equation that the current latched active power retention value equals the current active power retention value. Within the predicted phase current safety domain, sequence current dictionary optimization is performed to obtain the optimal sequence current reference, which includes: Using the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor as voltage references, and the candidate positive-sequence current reference and the candidate negative-sequence current reference as optimization variables, the average active power is calculated, and the expression is: ， In the formula, The value represents the average active power. A positive value indicates that the grid-side converter injects active power into the grid, while a negative value indicates that it absorbs active power from the grid. For the measured positive sequence voltage phasor, As a candidate positive sequence current reference To measure the negative sequence voltage phasor, As a candidate negative sequence current reference, This is a complex conjugate operation. This is for operations involving the real part of complex numbers; The average active power is equal to the currently latched active power retention value. As an equality constraint, minimizing the remaining positive-sequence voltage exceedance is the first priority, minimizing the remaining negative-sequence voltage exceedance is the second priority, and minimizing the sequence current change is the third priority. Within the predicted phase current safety domain, sequence current dictionary optimization is performed to obtain the optimal sequence current reference. The decision vector for the sequence current dictionary optimization is: ， In the formula, The decision vector for optimizing the order of the current dictionary. and These are the real and imaginary parts of the candidate positive-sequence current reference, respectively. and These are the real and imaginary parts of the candidate negative sequence current reference, respectively. The positive-sequence voltage remaining limit is a non-negative relaxation variable. The remaining excess of negative sequence voltage is a non-negative relaxation variable. The second-order cone upper bound auxiliary variable is used for the sequence current reference change. It is the transpose symbol; The common feasible set of ordered current dictionary order optimization Includes: the first-order current closed-loop model and sequence voltage prediction equation, the prediction execution phase current safety domain, positive sequence voltage constraints and negative sequence voltage constraints, the equation constraint that the average active power equals the active power retention value, rated capacity constraints, second-order cone constraints on sequence current change, and non-negative relaxation variable constraints. The order current dictionary optimization is performed sequentially in the following three layers: The first layer, in the public feasible set The expression for minimizing the residual positive-sequence voltage limit is: ， In the formula, This represents the minimum remaining threshold in the positive order, i.e., the optimal value obtained from the first level of optimization. Indicates in the common feasible set Inner decision vector Take the objective function Minimal operation; The second layer involves locking the optimal value from the first layer, and then considering the common feasible set. The expression for minimizing the residual negative sequence voltage limit is: ， In the formula, This represents the minimum residual threshold in the negative order, i.e., the optimal value obtained from the second level of optimization. The non-negative lexicographical order locking tolerance for the positive-order optimal value is a preset constant. The locking constraint for the first-level optimal value means that the remaining positive-sequence voltage limit during the second-level optimization must not exceed the first-level optimal value plus the tolerance. The third layer, after locking the optimal values ​​of the first and second layers, is based on the common feasible set. The expression for the minimum sequence current change is: ， In the formula, This is the decision vector corresponding to the optimal sequence current reference, i.e., the optimal solution obtained from the third layer of optimization. This is a locking constraint for the second-level optimal value. The non-negative lexicographical order locking tolerance for the negative-order optimal value is a preset constant. To make the objective function Decision vector when the minimum value is obtained The value of .

8. The active and reactive power coordinated support method for a grid-type wind turbine generator according to claim 1, characterized in that, When the minimum remaining threshold for positive sequence exceeds the positive sequence entry threshold, or the minimum remaining threshold for negative sequence exceeds the negative sequence entry threshold, or the predicted execution phase current safety domain is an empty set, the active power regulation degree of freedom is opened and active-reactive joint dictionary order optimization is performed to obtain the jointly optimized positive sequence current reference and negative sequence current reference, including: Set the threshold value for the minimum remaining excess quantity in the ascending order to enter the joint optimization phase. The threshold value for exiting the joint optimization phase with the minimum remaining quantity in the ascending order. Threshold value for entering the joint optimization stage with the minimum negative residue threshold. The threshold value for exiting the joint optimization phase with the minimum negative remainder. ; When the minimum remaining quantity in the ascending order exceeds the limit Greater than the positive sequence entry threshold Or the minimum residual quantity in negative order Greater than the negative order entry threshold , or the aforementioned public feasible set When the set is empty, the active power adjustment degree of freedom is opened and active power-reactive power joint lexicographical order optimization is performed. The decision vector for the active power-reactive power joint lexicographical order optimization is: ， In the formula, The decision vector for optimizing the joint lexicographical order of active and reactive power. This is the non-negative active power reduction relative to the active power retention value. , The optimized average active power, This represents the active power retention value latched before optimization in the k-th control cycle. and These are the real and imaginary parts of the candidate positive-sequence current reference, respectively. and These are the real and imaginary parts of the candidate negative sequence current reference, respectively. The positive-sequence voltage remaining limit is a non-negative relaxation variable. The remaining excess of negative sequence voltage is a non-negative relaxation variable. The second-order cone upper bound auxiliary variable is used for the sequence current reference change. It is the transpose symbol; The common feasible set of active-reactive joint lexicographical order optimization It includes: the first-order current closed-loop model and sequence voltage prediction equation, the prediction execution phase current safety domain, positive-sequence voltage constraints and negative-sequence voltage constraints, rated capacity constraints, second-order cone constraints for sequence current change, average active power boundary constraints, and non-negative relaxation variable constraints. The average active power boundary constraints are: ， In the formula, The lower limit of the grid-side average active power in the k-th cycle is determined by the allowable energy absorption of the DC bus. The active-reactive joint lexical order optimization is performed sequentially at the following four levels: The first layer, in the public feasible set The expression for minimizing the residual positive-sequence voltage limit is: ， In the formula, To jointly optimize the optimal value of the positive-order minimum residual limit obtained in the first layer. Indicates in the common feasible set Inner decision vector Take the objective function Minimal operation; The second layer involves locking the optimal value from the first layer, and then considering the common feasible set. The expression for minimizing the residual negative sequence voltage limit is: ， In the formula, To jointly optimize the optimal value of the negative-order minimum residual threshold obtained in the second layer. Locking constraints for the first-level optimal value; The third layer, after locking the optimal values ​​of the first and second layers, is based on the common feasible set. The expression for minimizing the active power reduction is: ， In the formula, To jointly optimize the minimum active power reduction obtained from the third layer, Locking constraints for the second-level optimal value; In the fourth layer, after locking the optimal values ​​of the first, second, and third layers, the values ​​are then considered in the common feasible set. The expression for the minimum sequence current change is: ， In the formula, These are the decision vectors corresponding to the jointly optimized positive-sequence current reference and negative-sequence current reference. This is a locking constraint for the third-level optimal value. The non-negative lexicographical order locking tolerance for the optimal value of active power reduction is a preset constant. This indicates that the objective function Decision vector when the minimum value is obtained The value of ; When the positive order minimum remaining limit is exceeded and the negative order minimum remaining limit quantity Simultaneously satisfy and And continuously preset the quantity During each control cycle, the active power regulation degree of freedom is closed, and the control strategy is switched from the active-reactive joint dictionary order optimization back to the sequence current dictionary order optimization, wherein... It is a preset positive integer representing the number of continuous control cycles required to exit the joint phase.

9. A grid-type wind turbine active-reactive power coordination support system, characterized in that, include: The transformation module is configured to collect the three-phase voltage and three-phase current at the grid connection point, and obtain the positive-sequence voltage d and q-axis components, positive-sequence current d and q-axis components, negative-sequence voltage d and q-axis components, and negative-sequence current d and q-axis components after positive-sequence and negative-sequence separation. All d and q-axis components are transformed to the same stationary complex phasor coordinate system to obtain the measured positive-sequence voltage phasor, measured positive-sequence current phasor, measured negative-sequence voltage phasor, and measured negative-sequence current phasor. The calculation module is configured to, based on candidate positive-sequence current references and candidate negative-sequence current references, and using the measured positive-sequence current phasors and the measured negative-sequence current phasors as current state quantities, recursively derive the predicted execution positive-sequence current phasors and the predicted execution negative-sequence current phasors through a first-order current closed-loop model, and obtain the predicted positive-sequence voltage phasors and the predicted negative-sequence voltage phasors based on the predicted execution positive-sequence current phasors and the predicted execution negative-sequence current phasors, the measured positive-sequence voltage phasors and the measured negative-sequence voltage phasors, and the grid-connected equivalent sequence impedance; The construction module is configured to synthesize the predicted execution positive sequence current phasor and the predicted execution negative sequence current phasor into a three-phase predicted execution current phasor according to the symmetrical component relationship, and construct the predicted execution phase current safety domain with the constraint that the amplitude of the three-phase predicted execution current phasor does not exceed the phase current limit allowed by the converter. The first optimization module is configured to use the measured positive-sequence voltage phasor and the measured negative-sequence voltage phasor as voltage references, the candidate positive-sequence current reference and the candidate negative-sequence current reference as optimization variables, calculate the average active power, and perform sequence current dictionary order optimization within the predicted execution phase current safety domain with the average active power equal to the currently latched active power retention value as an equality constraint to obtain the optimal sequence current reference. The second optimization module is configured to open the active power regulation degree of freedom and perform active-reactive joint dictionary order optimization when the minimum remaining limit of positive sequence is greater than the positive sequence entry threshold, or the minimum remaining limit of negative sequence is greater than the negative sequence entry threshold, or the predicted execution phase current safety domain is an empty set, so as to obtain the jointly optimized positive sequence current reference and negative sequence current reference. The output module is configured to output the positive-sequence current reference and negative-sequence current reference included in the optimal sequence current reference, or the jointly optimized positive-sequence current reference and negative-sequence current reference, as the command values ​​of the positive-sequence current control loop and the negative-sequence current control loop, respectively.

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