A new energy station fault ride-through active support method based on two-dimensional droop hierarchical control

Abstract

The application provides a new energy station fault ride-through active support method based on two-dimensional droop hierarchical control, and relates to the technical field of power system power electronic conversion control. Station-level control corrects positive and negative sequence admittance matrix through real-time monitoring and dynamic correction, iteratively calculates the multi-dimensional safety boundary of the converter, and solves the two-dimensional droop parameters for maximizing the active output through primary and secondary optimization alternating iteration within the boundary. The device-level control receives the parameters, fits and constructs the two-dimensional droop surface of the positive and negative sequence voltage to the active and reactive current instruction mapping, and realizes the table lookup response based on the measured voltage through the surface when the short-circuit fault occurs. The application considers the active and reactive power cooperation and the positive and negative sequence coupling, greatly improves the active support capability under the premise of ensuring the absolute safety of the multi-dimensional stress of the device, and effectively reduces the active power shortage of the power grid during the fault.

Description

Technical Field

[0001] This invention relates to the field of power electronic conversion control technology in power systems, and in particular to a fault ride-through active power support method for new energy power plants based on two-dimensional droop hierarchical control. Background Technology

[0002] my country's installed capacity of renewable energy power plants continues to grow. Taking the 940 MW Meigu Lama photovoltaic project in Liangshan Prefecture as an example, the planned construction scale of this project is 940 MW, indicating that renewable energy power plants are developing towards larger capacities. At the same time, existing fault ride-through schemes for renewable energy power plants focus on voltage support, neglecting the need for active power support, and still retaining a large margin in the utilization of the controllable capacity of renewable energy power plants. Therefore, when a short-circuit fault occurs in a renewable energy power plant, the existing fault ride-through control strategy based on voltage support will lead to an active power deficit of hundreds of megawatts in the plant, which in severe cases can cause grid frequency drops and even trigger the stability control system, posing challenges to the safe and stable operation of the power system.

[0003] To address the active power support requirements of new energy power plants during fault ride-through, existing technologies offer corresponding solutions. For example, Chinese patent application CN119171470A proposes a frequency and voltage support control method for energy storage power plants in weak power grids. However, this method bases active and reactive power output on different indicators (reactive power based on voltage amplitude, active power based on voltage frequency), making it difficult to achieve coordinated control of active and reactive power. Another example is Chinese patent CN120073707A, which considers adjusting the phase angle of the current in new energy power plants to increase active power generation, but the calculation... The method is limited to symmetrical faults and does not consider the coupling between positive and negative sequence components under asymmetrical faults. Furthermore, the scheme does not consider the boundary conditions of current command during fault ride-through of new energy power plants. For example, Chinese patent CN120566631A proposes a method for calculating the optimal ratio of active and reactive current for new energy power plants under different fault conditions. However, this scheme does not consider the coordinated support of active and reactive power, and its calculation of current command during fault ride-through of new energy power plants does not consider the constraints of switching device voltage, grid connection point voltage, and DC side active power.

[0004] The above-mentioned schemes focus on energy storage frequency-voltage support or multi-site current collaborative distribution, respectively. The published texts do not show the combination of worst-case fault type / location search, multi-dimensional equipment constraints and positive and negative sequence voltage-current two-dimensional droop mapping into the full process from site level to equipment level described in this application.

[0005] In summary, existing fault ride-through active power support methods do not take into account the coordination of active and reactive power, as well as the positive and negative sequence coupling. Therefore, the proposed fault ride-through control methods for renewable energy power plants cannot achieve coordinated control of active and reactive power. Thus, for renewable energy power plants under fault conditions, a fault ride-through control method that considers the coordination of active and reactive power and the positive and negative sequence coupling is proposed. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention provides a fault ride-through control method for renewable energy power plants that offers rapid control and considers the coupling effect of active and reactive power during power plant faults: a fault ride-through active power support method based on two-dimensional droop-layered control. This method uses a two-dimensional droop surface based on the positive and negative sequence voltage-active and reactive current commands at the power plant's grid connection point for fault ride-through control. While ensuring that the current stress of the converter equipment switching devices, DC bus voltage fluctuations, grid connection point voltage stress, and maximum active power of the renewable energy power plant do not exceed limits, it effectively reduces the active power deficit during asymmetrical short-circuit faults at the renewable energy power plant.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: The present invention provides a method for active power support for fault ride-through of new energy power stations based on two-dimensional droop-level hierarchical control. The method includes station-level control and equipment-level control, and specifically includes the following steps: S1. Establish the initial nodal admittance matrix based on the online impedance identification results of the grid connection point voltage and grid connection point current of the new energy power station. The adaptive correction coefficient is calculated based on the real-time voltage fluctuation amplitude at the power station's grid connection point. According to the adaptive correction coefficient Dynamically corrected nodal admittance matrix The dynamically updated node admittance matrix is ​​obtained. ; S2. Update the node admittance matrix dynamically. Based on the operating parameters of the equivalent converter equipment at the power station, determine the set of operational safety boundaries for the power generation unit, including voltage boundaries, current boundaries, and power boundaries. ; S3. Establish the main optimization objective function with the goal of maximizing the output active power during the fault period. Using a two-dimensional droop parameter matrix As the main optimization decision variables, the set of operational safety boundaries for power generation units is... Perform optimization calculations within the constraints and save the two-dimensional droop parameter matrix obtained from the main optimization calculations. Used for secondary optimization calls; S4. Construct a secondary optimization objective function based on the maximum values ​​of various physical stresses during the fault period. Using fault conditions as secondary optimization decision variables, the worst-case fault condition is optimized and calculated within the range of fault condition variations. Save the worst-case failure conditions Used for primary optimization calls; S5, Equipment-level control receives the two-dimensional droop parameter matrix transmitted by the site-level control. The positive sequence voltage amplitude from the power station grid connection point is constructed using a bilinear fitting algorithm. Negative sequence voltage amplitude at the grid connection point of the power station Initial value of positive sequence active current command arriving at the station Initial value of positive sequence reactive current command for the power station Initial value of negative sequence reactive current command for power station The current command of the two-dimensional drooping surface; S6. After a short-circuit fault occurs, the converter equipment-level control monitors the positive sequence voltage amplitude at the grid connection point of the power station in real time. Negative sequence voltage amplitude at the grid connection point of the power station Based on the positive sequence voltage amplitude at the grid connection point of the power station Negative sequence voltage amplitude at the grid connection point of the power station And the mapping relationship of the two-dimensional drooping surface of the current command, to adjust the initial value of the positive sequence active current command of the power station. Initial value of positive sequence reactive current command for the power station Initial value of negative sequence reactive current command for power station This enables rapid fault response through hierarchical control.

[0008] In the preferred scheme, the station-level control constructs the node admittance matrix. Iterative calculation of the power generation unit's operational safety boundary set Construct a two-dimensional droop parameter matrix that alternates between primary and secondary optimization. Optimize the solution model, nodal admittance matrix The dynamic correction method includes establishing the initial stage nodal admittance matrix based on the online impedance identification results. And based on the real-time voltage fluctuation amplitude of the power station grid connection point measured in real time. Adaptive correction coefficients are calculated through feedforward control. Using adaptive correction coefficients Dynamically adjust the initial nodal admittance matrix Generate dynamically updated node admittance matrices .

[0009] In the preferred scheme, the set of operational safety boundaries for the power generation unit The solution relies on a set of inequalities constructed by various physical stresses, including current stress constraints on switching devices, DC bus voltage fluctuation constraints, grid connection point voltage stress constraints, and maximum active power constraints on the DC side. The fault conditions include the fault location and the fault type. The fault location covers the impedance from the fault point to the AC power grid. and the impedance from the grid connection point of the substation to the fault point The fault types cover three-phase short circuit faults, two-phase short circuit faults, two-phase ground faults, and single-phase short circuit faults.

[0010] In the preferred scheme, the set of operational safety boundaries for the power generation unit is calculated iteratively. The method includes setting a set of fault conditions before alternating iterations. The estimated fault location is specified as the initial value; step S4 calculates the worst-case fault condition. Then, the worst-case failure conditions will be... Add to the fault condition set In the middle, and the worst failure conditions. The intersection of the corresponding feasible boundary region and the existing feasible safety boundary region is used to realize the set of safe boundary regions for the operation of the power generation unit. The boundary is contracting inward.

[0011] In the preferred scheme, the main optimization is of the objective function. Set of fault conditions The sum of the active power transmission expressions corresponding to each sudden operating condition, whereby the active power transmission expression is derived from the positive sequence active current command of the power station. Positive sequence voltage amplitude at the grid connection point of the power station The product operator determines this; Two-dimensional droop parameter matrix It contains 9 regulation and control elements: initial value of positive sequence active current command. Positive sequence voltage-positive sequence active current command two-dimensional droop parameter Two-dimensional droop parameters of negative sequence voltage-positive sequence active current command Initial value of positive sequence reactive current command Positive sequence voltage-positive sequence reactive current command two-dimensional droop parameter Two-dimensional droop parameters of negative sequence voltage-positive sequence reactive current command Initial value of negative sequence reactive current command Two-dimensional droop parameters of positive sequence voltage-negative sequence reactive current command Two-dimensional droop parameters of negative sequence voltage-negative sequence reactive current command .

[0012] In the preferred scheme, during the alternating iterative solution process of steps S3 and S4, the worst-case fault condition is determined. The iteration termination is determined by the per-unit values ​​of various physical stresses of the converter calculated based on the upper limit of stress; if the worst-case fault condition is... If all per-unit values ​​of the physical stresses of the converter, with the upper limit of stress as the baseline, are less than or equal to the normalization threshold constant 1.0, then the alternating iteration terminates, and a globally converged two-dimensional droop parameter matrix is ​​output. .

[0013] In the preferred embodiment, device-level control is based on a two-dimensional droop parameter matrix. Constructing a two-dimensional droop surface for current commands and implementing fault ride-through control based on the two-dimensional droop surface for current commands, step S5 includes calling the two-dimensional droop parameter matrix. The spatial coordinates of the top edge nodes of the two-dimensional drooping surface under the current command are clearly defined, and the spatial surface is established by two-dimensional mesh interpolation fitting. The method for calculating the spatial coordinates of top-level edge nodes includes setting the positive sequence voltage amplitude at the grid connection point of the substation during fault ride-through. The upper and lower limits of the change and the negative sequence voltage amplitude at the grid connection point of the power station The upper and lower limits of the variation are combined to form a limit phasor coordinate system and substituted into the two-dimensional droop parameter matrix. The characteristic equation is used to obtain the current command output value corresponding to the limit phasor coordinate system.

[0014] In the preferred embodiment, the characteristic equation for the control command corresponding to the two-dimensional drooping surface output based on the current command is calculated algebraically as follows: Station positive sequence active current command Used to support active power output; Power station positive sequence reactive current command It is used to support positive sequence voltage and indirectly improve active power output; negative sequence reactive current command for power station This is used to reduce voltage asymmetry at the grid connection point; At the same time, the negative sequence active current command is forcibly set to zero in the equipment-level control stage.

[0015] In the preferred embodiment, step S6, the fault rapid response process based on hierarchical control, specifically includes: the converter equipment-level control calls the local voltage transformer to monitor the measured grid-side voltage signal, and the positive sequence voltage amplitude at the substation grid connection point is obtained after decoupling through a second-order generalized integrator phase-locked loop module. Negative sequence voltage amplitude at the grid connection point of the power station The decoupling result is mapped into the two-dimensional drooping surface of the current command, and the instantaneous reference current command signal is retrieved and sent to the underlying pulse width modulator of the power generation equipment to perform the injection action.

[0016] In the preferred embodiment, the control method actively blocks the negative sequence active current during the fault period, and the command generation stage forces the negative sequence active current of the power station to be a zero per-unit constant in order to reduce the second harmonic power oscillation caused by the power station current output.

[0017] In a preferred embodiment, the present invention also provides a computer device, the computer device including at least one processor coupled to at least one memory, the memory storing at least one computer program or instruction, wherein the computer program or instruction is loaded and executed by the processor to implement the steps of the new energy power station fault ride-through active power support method based on two-dimensional drooping hierarchical control as described in any of the above embodiments.

[0018] In a preferred embodiment, the present invention further provides a computer-readable storage medium, wherein a computer program or instructions are stored on the computer-readable storage medium, and when the computer program or instructions are executed by a processor, the steps of the new energy power station fault ride-through active power support method based on two-dimensional drooping hierarchical control as described in any of the above embodiments are implemented.

[0019] In a preferred embodiment, the present invention further provides a computer program product, including a computer program or instructions, wherein when the computer program or instructions are executed by a processor, the steps of the fault ride-through active power support method for new energy power stations based on two-dimensional drooping hierarchical control as described in any of the above embodiments are implemented.

[0020] This invention provides a fault ride-through active power support method for new energy power stations based on two-dimensional droop-layer control. Through the coordination of the above structures, it has the following advantages compared with existing methods: Compared to setting current commands solely based on fixed fault conditions, this invention dynamically updates the node admittance matrix based on online identification results of grid connection point voltage and current. Through alternating iterations of primary optimization and worst-case fault condition search, a two-dimensional droop parameter matrix is ​​determined within the set of operational safety boundaries. Equipment-level control converts this matrix into a current reference value mapping that can be interpolated online based on measured positive and negative sequence voltages. This improves the active power support capability during faults while satisfying constraints on converter current, voltage, DC bus voltage fluctuations, and DC-side active power. Attached Figure Description

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a flowchart of the process logic of this invention; Figure 2 This is a schematic diagram of the new energy power station grid connection system of the present invention; Figure 3 This is a schematic diagram illustrating the alternating iteration of primary and secondary optimizations in this invention; Figure 4 This is a two-dimensional drooping surface plot of the current command corresponding to the fault ride-through control method proposed in this invention in a specific embodiment; Figure 5 This is a stress analysis result diagram corresponding to a specific embodiment of the fault ride-through control method proposed in this invention; Figure 6 This is a diagram showing the support effect of the fault-crossing control method proposed in this invention in a specific embodiment; Figure 7 This is a simulation result diagram of stress analysis in a specific embodiment of the fault ride-through control method proposed in this invention; Figure 8 This is a simulation verification diagram of the collaborative support effect of the fault ride-through control method proposed in this invention in a specific embodiment. Detailed Implementation

[0022] To better understand the purpose, system architecture, and functional implementation of this embodiment, the embodiments and features described herein can be combined with each other without conflict. The exemplary embodiments disclosed herein will be described below with reference to the accompanying drawings, including specific technical details disclosed to aid understanding; however, these details should be considered exemplary rather than restrictive. Therefore, those skilled in the art should understand that various improvements and adjustments can be made to the embodiments described herein without departing from the scope and core ideas of the invention. Similarly, for clarity, detailed descriptions of well-known technologies, functions, and structures are omitted in the following description.

[0023] Example 1: like Figure 1 As shown, this technical solution is responsible for complex environment perception, constraint boundary iterative solution, and control surface parameter optimization in the station-level control; and for calling control surface parameters and converting voltage space parameters into underlying drive current pulses in the equipment-level control, ensuring seamless closed loop in each link.

[0024] The grid-connected topology of the new energy power plant in this embodiment includes the new energy power plant and the AC power grid that collects and transmits the energy to other regions.

[0025] Preferably, a cluster of new energy power generation equipment that can be equivalent to a single power station also falls within the scope of new energy power stations defined in this embodiment.

[0026] according to Figure 2 As shown in the schematic diagram of the new energy power station grid connection system, the system hardware baseline parameters are set as shown in Table 1 below during specific implementation: Table 1 Parameters of New Energy Power Station Grid Connection System

[0027] The new energy power plant grid connection system to which this invention applies includes a new energy power plant or a cluster of new energy power generation equipment that can be equivalent to a single power plant, a power grid, and transmission lines connecting the power plant and the power grid, among other infrastructure.

[0028] Specifically, for ease of explanation, in the following embodiments, the new energy power station grid connection system targeted by this patent is as follows: Figure 2 As shown in Table 1, the system parameter settings are as follows. The rated power of the power station is 500MW, the rated voltage of the system is 220kV, and the impedance per unit length of the line is... The length of the transmission line from the station is 100km.

[0029] In practice, the hardware boundaries and physical parameters of the new energy power station grid connection system are the foundation for all subsequent boundary calculations.

[0030] Preferably, the rated power of a new energy power station is defined as the rated power of the power station. The system rated voltage is defined as the system rated voltage. The line impedance per unit length is defined as the line impedance per unit length. The length of the outgoing line from the station is defined as the length of the outgoing line from the station. .

[0031] This embodiment provides a fault ride-through active power support method for new energy power stations based on two-dimensional droop-layer control. The specific steps are as follows: S1. Establish the initial nodal admittance matrix based on the online impedance identification results of the grid connection point voltage and grid connection point current of the new energy power station. The adaptive correction coefficient k1 is calculated based on the real-time voltage fluctuation amplitude at the power station's grid connection point. Dynamically correct the initial nodal admittance matrix The dynamically updated node admittance matrix is ​​obtained. ; Establish the impedance equation under fault conditions. The parameter corresponding to the fault location is the impedance between the station and the fault point. and the impedance between the fault point and the power grid Its range of variation is: (1); Among them, the impedance from the fault point to the AC power grid The equivalent impedance of the transmission line between the point of short-circuit fault and the equivalent source of the AC power grid; its value range is in the complex domain. to Impedance from the grid connection point of the power station to the fault point The equivalent impedance of the transmission line between the grid connection point of the new energy power station and the point where the short-circuit fault occurred; its value range is in the complex domain. to .

[0032] Construct the node admittance matrix under the initial state. By real-time monitoring of the voltage and current of the renewable energy power plant connected to the grid, information such as line impedance and fault conditions is obtained. During algorithm initialization, a two-phase short circuit and a fault occurring at the midpoint between the power plant's grid connection point and the grid are assumed to be preset values. Construct the positive and negative order admittance matrices as shown in formulas (2) and (3): (2); in, ; ; (3); In the formula, , These are the positive and negative sequence voltages at the power station's grid connection point; , These are the positive and negative sequence voltages of the AC power grid. , These are the positive and negative sequence current output values ​​of the station; , The positive and negative sequence current output values ​​of the AC power grid; , The positive and negative sequence voltages at the fault point; , The output values ​​are the positive and negative sequence currents at the fault point. This is a comprehensive column vector describing the positive and negative sequence voltage phasors of each key node in a grid-connected system; This is a comprehensive column vector describing the positive and negative sequence current phasors of each key node in a grid-connected system. This is the initial positive-order admittance submatrix; This is the initial negative-order admittance submatrix. and This is the admittance matrix of the symmetric component network when the system fails and no feedforward compensation is performed.

[0033] To address the dynamic changes in the model, based on the real-time voltage fluctuation amplitude at the power station grid connection point measured in real time, the correction coefficients of the admittance matrix are dynamically adjusted through a feedforward loop. This enables rapid adaptive adjustment of the admittance matrix at the moment of fault occurrence or under voltage fluctuation conditions. The adaptive matrix is ​​as follows: (4); In the formula, The correction coefficients for adaptively correcting the positive and negative order admittance matrices, i.e. , This represents the real-time voltage fluctuation amplitude at the substation's grid connection point. Based on the rated voltage, the coordinated output accuracy of active and reactive power commands is optimized by adjusting the admittance matrix parameters in real time.

[0034] It should be noted that the dynamic admittance matrix correction method includes establishing a node admittance matrix universally applicable to both strong and weak power grids based on impedance parameter identification results, and dynamically adjusting the correction coefficients of the admittance matrix through a feedforward loop based on the real-time measured voltage fluctuation amplitude at the substation grid connection point. This achieves rapid adaptive adjustment of the admittance matrix at the moment of fault occurrence or under voltage fluctuation conditions. The feedforward loop construction method includes dynamically correcting the correction coefficients of the positive and negative sequence admittance matrices based on the characteristic that the closer the fault distance, the more severe the voltage drop at the grid connection point, and the real-time voltage fluctuation amplitude at the substation grid connection point, to achieve a rapid response considering voltage fluctuations.

[0035] S11. In specific implementation, the station-level control calls the voltage transformer and current transformer to identify the external topology online.

[0036] Among them, for the basic variables in formulas (1) to (3), the impedance from the fault point to the AC grid is defined as the impedance from the fault point to the AC grid. The impedance from the grid connection point to the fault point is defined as the impedance from the grid connection point to the fault point. .

[0037] Furthermore, the initial node admittance matrix is ​​defined as the initial node admittance matrix. Initial nodal admittance matrix Built-in initial positive order admittance submatrix and the initial negative order admittance submatrix .

[0038] S12. In this embodiment, for severe voltage transient drops that occur at the moment of a fault in a weak power grid, the algorithm introduces an adaptive feedforward correction mechanism.

[0039] Specifically, the station-level control system acquires the voltage signal at the station's grid connection point in real time and extracts the real-time voltage fluctuation amplitude at the station's grid connection point. .

[0040] S13. Therefore, the algorithm will calculate the real-time voltage fluctuation amplitude at the power station's grid connection point. With system rated voltage Substitute into the correction formula to calculate and generate adaptive correction coefficients. .

[0041] Preferably, the adaptive correction coefficient Station-level control utilizes adaptive correction coefficients. For the initial positive order admittance submatrix and the initial negative order admittance submatrix Perform scalar multiplication and impedance distance scaling mapping to ultimately generate a dynamically updated nodal admittance matrix. .

[0042] S2. Update the node admittance matrix dynamically. Based on the operating parameters of the equivalent converter equipment at the power station, determine the set of operational safety boundaries for the power generation unit, including voltage boundaries, current boundaries, and power boundaries. ; During the operation of the power generation unit, in order to prevent the equipment from disconnecting from the grid due to voltage or current exceeding limits, the following needs to be considered: First, the current stress boundary of switching devices: Under asymmetrical fault conditions, the grid-connected converter needs to inject a set active current and positive and negative sequence reactive current components into the grid. Due to the current-carrying capacity limitations of power electronic switching devices, the sum of the current components should satisfy the following boundary inequality: (5); In the formula, The positive sequence active current command of the power station is the current setpoint output by the converter under the positive sequence fundamental frequency for transmitting active power. The positive sequence reactive current command of the power station is the reactive current setpoint output by the converter under the positive sequence fundamental frequency to support the grid voltage. The negative sequence reactive current command of the power station is the reactive current setpoint output by the converter under the negative sequence fundamental frequency to suppress asymmetry. and The three-phase spatial phase angle vector is formed; This is the upper limit of the current stress on the switching devices, and the maximum peak value of the transient phase current that the IGBT module inside the converter can safely withstand. For the reason Second, the DC bus voltage fluctuation boundary: During an asymmetrical fault, the active power output from the AC side of the converter contains a second harmonic fluctuation component, which will cause fluctuations in the DC side capacitor voltage. The peak voltage of this fluctuation may exceed the device's withstand voltage. Based on instantaneous power theory, this boundary can be described as follows: (6); In the formula, The positive sequence voltage amplitude at the grid connection point of the power station is the envelope amplitude of the positive sequence voltage at the grid connection point extracted after asymmetric decoupling. The negative sequence voltage amplitude at the grid connection point of the power station is the envelope amplitude of the negative sequence voltage at the grid connection point extracted after asymmetric decoupling. This is the upper limit of DC bus capacitor voltage fluctuation, the maximum second harmonic voltage ripple amplitude that the DC side film capacitor can withstand, to prevent dielectric breakdown.

[0043] Third, the grid connection point voltage stress boundary: The converter grid connection point voltage is proportional to the voltage stress borne by the power electronic switching devices. To avoid device overvoltage, the current command must satisfy the following boundary inequality: (7); In the formula, For vectors The maximum value among the cosine values ​​of each component is used to evaluate the voltage superposition effect of the worst phase; The maximum voltage stress limit at the grid connection point is the highest transient phase voltage peak value that the circuit breaker and filter at the station outlet can withstand.

[0044] Fourth, the maximum active power boundary on the DC side: if the active power output of the converter exceeds the wind and solar power generation limit on its input side. The resulting power deficit will cause a voltage drop on the DC bus of the converter. According to the principle of power conservation, this boundary can be expressed as... (8); in, ; ; ; (9); In the formula, , The positive and negative sequence voltage amplitudes at the power station's grid connection point; It is half the sum of the positive-sequence voltage phase angle and the negative-sequence voltage phase angle at the grid connection point of the power station; For the reason and The three-phase spatial phase angle vector is formed; For vectors The maximum value among the cosine values ​​of each component; The upper limit of the current stress of the switching devices corresponding to the station is taken as 1.2 pu in this embodiment; This is the upper limit of the DC bus capacitor voltage fluctuation corresponding to the station, which is taken as 0.3pu in this embodiment; The upper limit of the grid connection point voltage stress corresponding to the power station is taken as 1.3 pu in this embodiment; The upper limit of the DC-side active power output of the power station is 1.0pu in this embodiment; the max(•) function is used to calculate the maximum value of the vector.

[0045] In summary, given the known fault conditions, the safety boundaries include the current stress boundary of the switching devices, the DC bus voltage fluctuation boundary, the grid connection point voltage stress boundary, and the maximum active power boundary on the DC side. Therefore, the boundary conditions... for: (10); Meanwhile, to avoid stress exceeding limits in power generation units due to incorrect fault location estimation, the boundary changes under different fault conditions need to be considered during the safety boundary calculation process. Therefore, an additional fault condition set is established during the boundary calculation process. Initially, this set only includes the fault location estimate as the initial value, and subsequent iterations are used to add more fault conditions to the set. During the optimization of control parameters, the solver calculates the safety boundary for each fault condition in the set, and the final safety boundary is obtained by intersecting the feasible regions of the safety boundaries.

[0046] It should be noted that the safety boundary construction method includes comprehensively considering the decision variable inequalities corresponding to different fault conditions and different types of boundaries, which serve as the output constraint conditions for the fault through current of the power generation unit, and establishing a decision variable safety boundary that continuously shrinks as fault conditions are added during the iteration process.

[0047] Fault conditions include at least the fault location and fault type. Fault condition supplementation methods include setting a fault condition set before optimization iteration, specifying the fault location estimate as the initial value; subsequently, fault conditions are continuously added to the set through optimization, measurement, impedance estimation, etc. The method of shrinking the safety boundary with iteration includes continuously adding new fault conditions or constraints during the iteration process, taking the intersection of their feasible region and the existing safe boundary feasible region as the new boundary, thus achieving boundary shrinkage.

[0048] S21. In specific implementation, the algorithm introduces a globally unique per-unit parameter definition: the upper limit of the current stress of the switching devices corresponding to the station is defined as the upper limit of the current stress of the switching devices. The preferred setting is 1.2; the upper limit of DC bus capacitor voltage fluctuation corresponding to the station is defined as the upper limit of DC bus capacitor voltage fluctuation. The preferred setting is 0.3; the upper limit of the grid connection point voltage stress corresponding to the power station is defined as the upper limit of the grid connection point voltage stress. The preferred setting is 1.3; the upper limit of the DC-side active power output of the power station is defined as the maximum active power boundary on the DC side. The preferred setting is 1.0.

[0049] S22, where the algorithm defines the command variable as the positive-sequence active current command of the power station. , Station positive sequence reactive current command Station negative sequence reactive current command And the voltage variable is mapped to the positive sequence voltage amplitude at the power station's grid connection point. Negative sequence voltage amplitude at the grid connection point of the power station .

[0050] Furthermore, the spatial phase angle parameter is mapped to half the sum of the positive-sequence voltage phase angle and the negative-sequence voltage phase angle at the power station's grid connection point. ; For the reason and The three-phase space phase angle vector is formed and vectors The maximum value of the cosine of each component .

[0051] S23. In this embodiment, the station-level control mathematically combines the four-dimensional physical constraints formed by formulas (5), (6), (7), and (8) to form the set of operational safety boundaries for the power generation unit in the initial state. Set of safety boundaries for power generation unit operation It is a high-dimensional feasible domain space geometry defined by a system of nonlinear inequalities.

[0052] S24. In practical implementation, in order to cope with drastic changes in topology, the algorithm pre-defines a set of fault conditions. During the algorithm initialization phase, the set of fault conditions is... It only includes the initial estimate of the midpoint short circuit.

[0053] S25. Therefore, in the subsequent alternating primary and secondary iterative calculations, the station-level control executes boundary contraction logic. Whenever a new extreme fault condition is received, the system calculates the local inequality feasible region corresponding to that new condition and compares this local feasible region with the current set of operational safety boundaries for the generating unit. Perform the intersection operation.

[0054] S26. By taking the intersection operation, the set of safe boundaries for the power generation unit is obtained. The absolute volume continuously contracts and converges inward, thus establishing an absolutely safe isolation barrier.

[0055] S3. Construct the main optimization objective function and decision variables, using the output active power during the fault period as the objective function and the two-dimensional droop parameter as the decision variable, and perform optimization calculations within the safety boundary. Save the two-dimensional droop parameter obtained from the optimization calculation for secondary optimization. The primary objective function is the sum of the active power output expressions for each operating condition in the fault condition set, where the active power output expression is the product of the positive-sequence active current command and the positive-sequence voltage expression at the grid connection point. Therefore, the primary objective function is constructed as follows: for: (11); In the formula, i is the fault condition index; This is a set of fault conditions, considering all fault types and fault locations, totaling... Each working condition; For the first The grid connection point voltage of the substation is restored under fault conditions; For the first The output complex current of the station under each operating condition; It is a function that takes the real part of a complex number; for The conjugate of complex numbers; It is a function taking the conjugate complex number. Based on the voltage and current stress limits of the power station, the safety boundary of the power station current command under this fault condition is analyzed to ensure that the voltage and current stress of the power station does not exceed the limits under the fault condition. Based on the obtained objective function Boundary conditions Optimize the solution of the two-dimensional droop parameters.

[0056] ; (12); In the formula, This is a two-dimensional droop parameter matrix containing the initial values ​​of the positive-sequence active current command. Positive sequence voltage-positive sequence active current command two-dimensional droop parameter Two-dimensional droop parameters of negative sequence voltage-positive sequence active current command Initial value of positive sequence reactive current command Positive sequence voltage-positive sequence reactive current command two-dimensional droop parameter Two-dimensional droop parameters of negative sequence voltage-positive sequence reactive current command Initial value of negative sequence reactive current command Two-dimensional droop parameters of positive sequence voltage-negative sequence reactive current command Two-dimensional droop parameters of negative sequence voltage-negative sequence reactive current command The relationship between the two-dimensional droop parameter and the current command is as follows: (13); S31. In specific implementation, the algorithm establishes the main optimization objective function as defined as the main optimization objective function. The main optimization objective function is... This is used to quantify the overall contribution of new energy power plants to filling the active power deficit in the power grid.

[0057] S32, where the algorithm reconstructs the core control parameters described by equation (13), and defines the optimization kernel consisting of 9 key coefficients as a two-dimensional droop parameter matrix. .

[0058] S33. In this embodiment, the station-level control invokes the Interior Point Method nonlinear optimization solver module. The solver uses a two-dimensional droop parameter matrix. The nine elements within are decision-making independent variables, representing the set of operational safety boundaries for the power generation unit. Gradient optimization is performed within the designated hard isolation zone.

[0059] Therefore, the solver calculates the two-dimensional droop parameter matrix that enables active power transmission to reach its extreme value in the current iteration step. .

[0060] S4. Construct the objective function and decision variables for secondary optimization. Using each physical stress as the objective function and the fault condition as the decision variable, optimize the worst-case fault condition within its variation range. Save the optimized worst-case fault condition for primary optimization. Each physical stress includes switching device current stress constraints, DC bus voltage fluctuation constraints, grid connection point voltage stress constraints, and DC side maximum active power constraints.

[0061] Using the various physical stresses during the failure period as optimization objectives, a secondary optimization objective function is constructed: (14); in, (15); In the formula, The instantaneous absolute peak value of the converter arm current is dynamically calculated from the current stress function value of the switching device. The DC bus voltage fluctuation function value is the bus voltage pulsation amplitude dynamically calculated from the second harmonic power backflow. The voltage stress function value at the grid connection point, dynamically calculated as the peak value of the combined voltage borne by the circuit breaker terminals; This represents the active power function value on the DC side, which is the actual active power consumed by the power station when transmitting power to the AC side.

[0062] Based on the objective function and boundary conditions obtained from S1 and S2, the fault conditions corresponding to the worst working condition are optimized and solved.

[0063] ; ; (16); In equation (16), The maximum impedance of the line is the overall fixed series equivalent impedance of the transmission line from the new energy power station.

[0064] like Figure 3 As shown, the primary and secondary optimizations are iterated alternately until the voltage and current of the station do not exceed the limits under the worst operating conditions. The two-dimensional drooping surface obtained from the optimization calculation is sent to each converter device in the station. The iterative solution results based on the embodiment are shown in Table 2.

[0065] Table 2. Iterative solution results of two-dimensional droop parameters

[0066] It should be noted that the worst failure condition corresponds to the working condition in which the two-dimensional droop parameter corresponding control method is most likely to exceed the stress limit. If the maximum value of each stress is less than or equal to 1 under this working condition, the two-dimensional droop parameter corresponding control method will not cause the stress to exceed the upper limit under other failure working conditions.

[0067] S41. In specific implementation, the algorithm introduces a red-blue adversarial mechanism to test the robustness of the current parameters. The optimization model of formulas (14) and (16) is defined as the secondary optimization objective function. .

[0068] S42. Among them, the secondary optimization step locks the two-dimensional droop parameter matrix transmitted from stage S3. Instead of using constants, external natural parameters such as fault type and the impedance from the fault point to the AC power grid are considered. impedance from the grid connection point of the power station to the fault point Activation is used as a decision variable, and the system scans the entire domain to find the singularity most likely to cause hardware failure. This singularity is defined as the worst-case failure condition. .

[0069] S43. In this embodiment, the station-level control executes a closed-loop feedback action, calculating the worst-case fault condition. Re-added to the fault condition set In the middle. Due to the addition of the new extreme operating condition, the set of safe operating boundaries for the power generation unit in stage S2. Performing the intersection operation again further shrinks the safety region, forcing the S3 stage to recalculate a more conservative and safer two-dimensional droop parameter matrix. .

[0070] S44. In specific implementation, the algorithm sets a hard convergence termination condition: when the worst-case fault condition occurs... Under the evaluation conditions, when all four per-unit values ​​of physical stress calculated by formula (15) are simultaneously less than or equal to the constant threshold of 1.0, the alternating iteration is considered to have converged. The algorithm terminates the loop and extracts the two-dimensional droop parameter matrix under the global convergence state. As shown in Table 2, the numerical solution group is recorded. Preferably, the two-dimensional droop parameters of positive sequence voltage and positive sequence active current are... It is set to 0.13, etc., and then distributed to the subsequent execution system layer.

[0071] S5. Receive the two-dimensional droop parameters transmitted by the station-level control, and construct a two-dimensional droop surface from the positive and negative sequence voltage amplitudes to the reference values ​​of positive sequence active, positive sequence reactive, and negative sequence reactive currents using a linear fitting method. In this embodiment, considering the definition of the positive and negative sequence voltage range for fault ride-through in the national standard, the positive sequence voltage amplitude at the substation grid connection point during fault ride-through is set. The calculation range for the upper and lower limits of the variation is from 0.0 pu to 0.9 pu, taking the negative sequence voltage amplitude at the grid connection point of the power station. The calculation range for the upper and lower limits of the variation is from 0.0 pu to 1.0 pu.

[0072] Substituting these values ​​into the current command calculation equation based on two-dimensional drooping surface control, the coordinates of the edge nodes of each surface are obtained as shown in Table 3.

[0073] Table 3. Solution results for edge nodes of two-dimensional drooping surfaces

[0074] After receiving the coordinates of the edge nodes, the power generation unit can reconstruct the specific current command's two-dimensional drooping surface based on a linear fitting method. The resulting two-dimensional drooping surface is as follows: Figure 4 As shown.

[0075] It should be noted that the two-dimensional droop surface construction method includes identifying the edge nodes of the two-dimensional droop surface based on the two-dimensional droop parameters transmitted by the station-level control, and establishing a complete two-dimensional droop surface through linear fitting. The edge node calculation method involves setting the upper and lower limits of the positive sequence voltage and the upper and lower limits of the negative sequence voltage corresponding to fault crossing, combining them pairwise into a phasor form of [positive sequence voltage, negative sequence voltage], and substituting them into the current reference value calculation equation composed of the two-dimensional droop parameters to obtain the current reference value corresponding to the edge node of each voltage range.

[0076] S51. In practical implementation, to avoid control delay caused by matrix multiplication performed by the underlying digital signal processor, the algorithm deploys a dimensionality reduction operation at the execution end. The device-level control receives the globally convergent two-dimensional droop parameter matrix. Based on national standard boundaries, a limit phasor coordinate system containing [0.0,0.0], [0.9,0.0], [0.0,1.0], and [0.9,1.0] is constructed. The device-level control inputs this limit phasor coordinate system into an algebraic equation to calculate the coordinate elevations of the four vertices of the current output plane, as shown in Table 3.

[0077] S52. The algorithm calls the bilinear interpolation fitting algorithm. Based on these four determined edge vertices, the positive sequence voltage amplitude at the power station grid connection point is used... Negative sequence voltage amplitude at the grid connection point of the power station Within the laid-out two-dimensional mesh, a continuous and smooth two-dimensional drooping surface of current command is generated, with a physical morphology as follows: Figure 4 As shown. This surface file is ultimately solidified into a look-up table, serving as the physical carrier for microsecond-level scheduling.

[0078] S6. After a short-circuit fault occurs, the converter equipment-level control monitors the positive and negative sequence voltages at the grid connection point in real time. Based on the real-time measured values ​​of the positive and negative sequence voltages at the grid connection point and the two-dimensional drooping surface, it adjusts the positive and negative sequence active and reactive current commands to achieve rapid fault response based on hierarchical control. The two-dimensional droop parameters obtained from the final iterative calculation are shown in Table 2. Based on this, a fault ride active power support control method for new energy power plants is constructed as follows: Figure 4 As shown, and its control effect is verified as follows. Figures 5 to 6 As shown.

[0079] in, Figure 5 The stress analysis shown indicates that the present invention can keep the stress of each voltage and circuit in the new energy power station within the upper limit during the process of changing fault conditions; Figure 6 The analysis of the active power support effect shown indicates that the present invention can improve the active power support capability of power stations by an average of 191% based on the control method corresponding to the national standard. Within the range of varying fault conditions, a specific fault scenario is considered, including a two-phase short circuit. , The verification results for stress and active support capabilities using MATLAB / Simulink are as follows: Figures 7 to 8 As shown, the simulation verified the control effect of the fault ride-through control method proposed in this invention in avoiding stress overrun and improving active power support capability. At the same time, the error of the theoretical analysis of the improvement effect of the collaborative support capability is only 0.16%, that is, the improvement effect in the theoretical analysis is 79.10%, and the improvement effect in the simulation analysis is 78.94%, which verifies the accuracy of the voltage and power calculation model during the fault.

[0080] In summary, this embodiment can take into account the coupling effect between active and reactive power outputs and between positive and negative sequence components after a fault within the new energy power station. Under the premise of fully ensuring the safety of voltage and current stress in the new energy power station, it can achieve coordinated support of active and reactive power and improve the fault ride-through active power support capability of the new energy power station.

[0081] S61. In practical implementation, once a physical fault occurs, the equipment-level control at the bottom layer of the converter is immediately awakened and enters a high-frequency interruption state. The converter front-end analog-to-digital conversion system captures the transient voltage of the power grid at a sampling rate of 10kHz.

[0082] S62. In this embodiment, the algorithm calls the second-order generalized integrator phase-locked loop module to extract the current positive-sequence voltage amplitude of the power station grid connection point at high speed within a millisecond-level window. Negative sequence voltage amplitude at the grid connection point of the power station .

[0083] S63. Therefore, the device-level control directly reads the two-dimensional drooping surface lookup table file of the current command frozen in stage S5, uses the obtained voltage amplitude to perform the addressing operation, and instantly calculates and outputs the initial value of the positive sequence active current command of the power station. Initial value of positive sequence reactive current command for the power station Initial value of negative sequence reactive current command for power station .

[0084] In addition, the device-level control converts the calculated instructions into pulse-width modulated pulses and sends them to the underlying IGBT gate driver to perform current injection. Figure 7 Displays the listed DC bus capacitor voltage ( Figure 7 (a) The relationship between the waveforms of the capacitor voltage, AC current and grid connection point voltage and the corresponding set upper limit; Figure 8 The active power waveforms of this method and the comparison method are shown during the simulation time period. The average active power values ​​marked in the figure are 0.34 pu and 0.19 pu, respectively. The above results indicate that under the simulation conditions and parameters, the current reference value obtained by this method can be used to improve active power output under the stated operating constraints. Example 2: In further detail with reference to Embodiment 1, the computer device includes: Processor, memory, communication bus, and computer programs stored in memory that can run on the processor.

[0085] The processor can call a computer program in memory, and when executing the program, implement the fault ride-through active power support method for new energy power stations based on two-dimensional droop hierarchical control provided in the above embodiments. The method includes: the method includes station-level control and equipment-level control, specifically including the following steps: S1. Establish the initial nodal admittance matrix based on the online impedance identification results of the grid connection point voltage and grid connection point current of the new energy power station. The adaptive correction coefficient is calculated based on the real-time voltage fluctuation amplitude at the power station's grid connection point. According to the adaptive correction coefficient Dynamically corrected nodal admittance matrix The dynamically updated node admittance matrix is ​​obtained. ; S2. Update the node admittance matrix dynamically. Based on the operating parameters of the equivalent converter equipment at the power station, determine the set of operational safety boundaries for the power generation unit, including voltage boundaries, current boundaries, and power boundaries. ; S3. Establish the main optimization objective function with the goal of maximizing the output active power during the fault period. Using a two-dimensional droop parameter matrix As the main optimization decision variables, the set of operational safety boundaries for power generation units is... Perform optimization calculations within the constraints and save the two-dimensional droop parameter matrix obtained from the main optimization calculations. Used for secondary optimization calls; S4. Construct a secondary optimization objective function based on the maximum values ​​of various physical stresses during the fault period. Using fault conditions as secondary optimization decision variables, the worst-case fault condition is optimized and calculated within the range of fault condition variations. Save the worst-case failure conditions Used for primary optimization calls; S5, Equipment-level control receives the two-dimensional droop parameter matrix transmitted by the site-level control. The positive sequence voltage amplitude from the power station grid connection point is constructed using a bilinear fitting algorithm. Negative sequence voltage amplitude at the grid connection point of the power station Initial value of positive sequence active current command arriving at the station Initial value of positive sequence reactive current command for the power station Initial value of negative sequence reactive current command for power station The current command of the two-dimensional drooping surface; S6. After a short-circuit fault occurs, the converter equipment-level control monitors the positive sequence voltage amplitude at the grid connection point of the power station in real time. Negative sequence voltage amplitude at the grid connection point of the power station Based on the positive sequence voltage amplitude at the grid connection point of the power station Negative sequence voltage amplitude at the grid connection point of the power station And the mapping relationship of the two-dimensional drooping surface of the current command, to adjust the initial value of the positive sequence active current command of the power station. Initial value of positive sequence reactive current command for the power station Initial value of negative sequence reactive current command for power station This enables rapid fault response through hierarchical control.

[0086] Furthermore, computer equipment also includes: The Communications Interface (CI) is used for communication between the memory and the processor.

[0087] The memory may include high-speed RAM, and may also include non-volatile memory, such as at least one disk drive.

[0088] If the memory, processor, and communication interface are implemented independently, they can be interconnected via a bus to communicate with each other. The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc.

[0089] To provide interaction with a user, the systems and techniques described herein can be implemented on a computer having: a display device for displaying information to the user (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor); and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the computer. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0090] Display devices are used to display images, videos, etc. Display devices may include display panels, which may employ liquid crystal displays (LCDs), organic light-emitting diodes (OLEDs), active-matrix organic light-emitting diodes (AMOLEDs), flexible light-emitting diodes (FLEDs), MiniLEDs, MicroLEDs, Micro-OLEDs, quantum dot light-emitting diodes (QLEDs), etc.

[0091] Alternatively, in a specific implementation, if the memory, processor, and communication interface are integrated on a single chip, then the memory, processor, and communication interface can communicate with each other through an internal interface.

[0092] On the other hand, embodiments of this application also provide a computer-readable storage medium storing a computer program thereon. When executed by a processor, the program implements the above-described method for active power support during fault ride-through at renewable energy power stations based on two-dimensional drooping hierarchical control. The method includes: the method comprises station-level control and equipment-level control, specifically including the following steps: S1. Establish the initial nodal admittance matrix based on the online impedance identification results of the grid connection point voltage and grid connection point current of the new energy power station. The adaptive correction coefficient is calculated based on the real-time voltage fluctuation amplitude at the power station's grid connection point. According to the adaptive correction coefficient Dynamically corrected nodal admittance matrix The dynamically updated node admittance matrix is ​​obtained. ; S2. Update the node admittance matrix dynamically. Based on the operating parameters of the equivalent converter equipment at the power station, determine the set of operational safety boundaries for the power generation unit, including voltage boundaries, current boundaries, and power boundaries. ; S3. Establish the main optimization objective function with the goal of maximizing the output active power during the fault period. Using a two-dimensional droop parameter matrix As the main optimization decision variables, the set of operational safety boundaries for power generation units is... Perform optimization calculations within the constraints and save the two-dimensional droop parameter matrix obtained from the main optimization calculations. Used for secondary optimization calls; S4. Construct a secondary optimization objective function based on the maximum values ​​of various physical stresses during the fault period. Using fault conditions as secondary optimization decision variables, the worst-case fault condition is optimized and calculated within the range of fault condition variations. Save the worst-case failure conditions Used for primary optimization calls; S5, Equipment-level control receives the two-dimensional droop parameter matrix transmitted by the site-level control. The positive sequence voltage amplitude from the power station grid connection point is constructed using a bilinear fitting algorithm. Negative sequence voltage amplitude at the grid connection point of the power station Initial value of positive sequence active current command arriving at the station Initial value of positive sequence reactive current command for the power station Initial value of negative sequence reactive current command for power station The current command of the two-dimensional drooping surface; S6. After a short-circuit fault occurs, the converter equipment-level control monitors the positive sequence voltage amplitude at the grid connection point of the power station in real time. Negative sequence voltage amplitude at the grid connection point of the power station Based on the positive sequence voltage amplitude at the grid connection point of the power station Negative sequence voltage amplitude at the grid connection point of the power station And the mapping relationship of the two-dimensional drooping surface of the current command, to adjust the initial value of the positive sequence active current command of the power station. Initial value of positive sequence reactive current command for the power station Initial value of negative sequence reactive current command for power station This enables rapid fault response through hierarchical control.

[0093] In another aspect, embodiments of this application also provide a computer program product, which includes a computer program that can be stored on a computer-readable storage medium. The computer program can execute computer instructions. When the computer program is executed by a processor, the computer can perform the above-described method for fault ride-through active power support for new energy power stations based on two-dimensional drooping hierarchical control. This method includes: the method comprises station-level control and equipment-level control, specifically including the following steps: S1. Establish the initial nodal admittance matrix based on the online impedance identification results of the grid connection point voltage and grid connection point current of the new energy power station. The adaptive correction coefficient is calculated based on the real-time voltage fluctuation amplitude at the power station's grid connection point. According to the adaptive correction coefficient Dynamically corrected nodal admittance matrix The dynamically updated node admittance matrix is ​​obtained. ; S2. Update the node admittance matrix dynamically. Based on the operating parameters of the equivalent converter equipment at the power station, determine the set of operational safety boundaries for the power generation unit, including voltage boundaries, current boundaries, and power boundaries. ; S3. Establish the main optimization objective function with the goal of maximizing the output active power during the fault period. Using a two-dimensional droop parameter matrix As the main optimization decision variables, the set of operational safety boundaries for power generation units is... Perform optimization calculations within the constraints and save the two-dimensional droop parameter matrix obtained from the main optimization calculations. Used for secondary optimization calls; S4. Construct a secondary optimization objective function based on the maximum values ​​of various physical stresses during the fault period. Using fault conditions as secondary optimization decision variables, the worst-case fault condition is optimized and calculated within the range of fault condition variations. Save the worst-case failure conditions Used for primary optimization calls; S5, Equipment-level control receives the two-dimensional droop parameter matrix transmitted by the site-level control. The positive sequence voltage amplitude from the power station grid connection point is constructed using a bilinear fitting algorithm. Negative sequence voltage amplitude at the grid connection point of the power station Initial value of positive sequence active current command arriving at the station Initial value of positive sequence reactive current command for the power station Initial value of negative sequence reactive current command for power station The current command of the two-dimensional drooping surface; S6. After a short-circuit fault occurs, the converter equipment-level control monitors the positive sequence voltage amplitude at the grid connection point of the power station in real time. Negative sequence voltage amplitude at the grid connection point of the power station Based on the positive sequence voltage amplitude at the grid connection point of the power station Negative sequence voltage amplitude at the grid connection point of the power station And the mapping relationship of the two-dimensional drooping surface of the current command, to adjust the initial value of the positive sequence active current command of the power station. Initial value of positive sequence reactive current command for the power station Initial value of negative sequence reactive current command for power station This enables rapid fault response through hierarchical control.

[0094] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus or device (such as a computer-based system, a processor-included system or other system that can fetch and execute instructions from, an instruction execution system, apparatus or device).

[0095] For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit a program for use in or in conjunction with an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing. Furthermore, a computer-readable medium can even be paper or other suitable media on which the program can be printed, since the program can be obtained electronically by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0096] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0097] The program code used to implement the methods of this disclosure may be written in any combination of one or more programming languages. This program code may be provided to a processor or controller of a general-purpose computer, special-purpose computer, or other programmable data processing apparatus, such that when executed by the processor or controller, the program code causes the functions / operations specified in the flowcharts and / or block diagrams to be implemented. The program code may be executed entirely on a machine, partially on a machine, as a standalone software package partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0098] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as a data server), or computing systems that include middleware components (e.g., an application server), or computing systems that include frontend components (e.g., a user computer with a graphical user interface or web browser through which a user can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., a communication network). Examples of communication networks include local area networks (LANs), wide area networks (WANs), and the Internet.

[0099] Computer systems can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. Client-server relationships are created by computer programs running on the respective computers and having a client-server relationship with each other.

[0100] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this disclosure can be achieved, and this is not limited herein.

[0101] The specific embodiments described above do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of this application.

Claims

1. A method for active power support during fault ride-through at renewable energy power stations based on two-dimensional droop-layered control, characterized in that, The method includes station-level control and equipment-level control, specifically including the following steps: S1. Establish the initial nodal admittance matrix based on the online impedance identification results of the grid connection point voltage and grid connection point current of the new energy power station. The adaptive correction coefficient is calculated based on the real-time voltage fluctuation amplitude at the power station's grid connection point. According to the adaptive correction coefficient Dynamically corrected nodal admittance matrix The dynamically updated node admittance matrix is ​​obtained. ; S2. Update the node admittance matrix dynamically. Based on the operating parameters of the equivalent converter equipment at the power station, determine the set of operational safety boundaries for the power generation unit, including voltage boundaries, current boundaries, and power boundaries. ; S3. Establish the main optimization objective function with the goal of maximizing the output active power during the fault period. Using a two-dimensional droop parameter matrix As the main optimization decision variables, the set of operational safety boundaries for power generation units is... Perform optimization calculations within the constraints and save the two-dimensional droop parameter matrix obtained from the main optimization calculations. Used for secondary optimization calls; S4. Construct a secondary optimization objective function based on the maximum values ​​of various physical stresses during the fault period. Using fault conditions as secondary optimization decision variables, the worst-case fault condition is optimized and calculated within the range of fault condition variations. Save the worst-case failure conditions Used for primary optimization calls; S5, Equipment-level control receives the two-dimensional droop parameter matrix transmitted by the site-level control. The positive sequence voltage amplitude from the power station grid connection point is constructed using a bilinear fitting algorithm. Negative sequence voltage amplitude at the grid connection point of the power station Initial value of positive sequence active current command arriving at the station Initial value of positive sequence reactive current command for the power station Initial value of negative sequence reactive current command for power station The current command of the two-dimensional drooping surface; S6. After a short-circuit fault occurs, the converter equipment-level control monitors the positive sequence voltage amplitude at the grid connection point of the power station in real time. Negative sequence voltage amplitude at the grid connection point of the power station Based on the positive sequence voltage amplitude at the grid connection point of the power station Negative sequence voltage amplitude at the grid connection point of the power station And the mapping relationship of the two-dimensional drooping surface of the current command, to adjust the initial value of the positive sequence active current command of the power station. Initial value of positive sequence reactive current command for the power station Initial value of negative sequence reactive current command for power station This enables rapid fault response through hierarchical control.

2. The method for active power support during fault ride-through of new energy power stations based on two-dimensional droop-layered control according to claim 1, characterized in that, Station-level control constructs node admittance matrix Iterative calculation of the power generation unit's operational safety boundary set Construct a two-dimensional droop parameter matrix that alternates between primary and secondary optimization. Optimize the solution model, nodal admittance matrix The dynamic correction method includes establishing the initial stage nodal admittance matrix based on the online impedance identification results. Initial nodal admittance matrix Including the initial positive-order admittance submatrix and the initial negative order admittance submatrix The real-time voltage fluctuation amplitude at the grid connection point of the power station is And based on the real-time voltage fluctuation amplitude of the power station grid connection point measured in real time. Adaptive correction coefficients are calculated through feedforward control. Using adaptive correction coefficients Dynamically adjust the initial nodal admittance matrix After scaling the equivalent impedances on both sides of the fault point, the positive-sequence admittance submatrix and the negative-sequence admittance submatrix are reassembled to generate a dynamically updated nodal admittance matrix. .

3. The method for active power support during fault ride-through of new energy power stations based on two-dimensional droop-layered control according to claim 1, characterized in that, Safety boundary set for power generation unit operation The system of inequalities constituted by physical stress constraints includes switching device current stress constraints, DC bus voltage fluctuation constraints, grid connection point voltage stress constraints, and DC side maximum active power constraints. The fault conditions include the fault location and the fault type. The fault location covers the impedance from the fault point to the AC power grid. and the impedance from the grid connection point of the substation to the fault point The fault types cover three-phase short circuit faults, two-phase short circuit faults, two-phase ground faults, and single-phase short circuit faults.

4. The method for active power support during fault ride-through of new energy power stations based on two-dimensional droop-layered control according to claim 2, characterized in that, The method for iteratively calculating the power generation unit's operational safety boundary set Csum includes setting a set of fault conditions before alternating iterations. Specify the fault location estimate as the initial value; Step S4 calculates the worst-case failure condition. Then, the worst-case failure conditions will be... Add to the fault condition set In the middle, and the worst failure conditions. The intersection of the corresponding feasible boundary region and the existing feasible safety boundary region is used to realize the set of safe boundary regions for the operation of the power generation unit. The boundary is contracting inward.

5. The method for active power support during fault ride-through of new energy power stations based on two-dimensional droop-layered control according to claim 4, characterized in that, Main optimization objective function Set of fault conditions The sum of the active power transmission expressions corresponding to each sudden operating condition, whereby the active power transmission expression is derived from the positive sequence active current command of the power station. Positive sequence voltage amplitude at the grid connection point of the power station The product operator determines this; Two-dimensional droop parameter matrix It contains 9 regulation and control elements: initial value of positive sequence active current command. Positive sequence voltage-positive sequence active current command two-dimensional droop parameter Two-dimensional droop parameters of negative sequence voltage-positive sequence active current command Initial value of positive sequence reactive current command Positive sequence voltage-positive sequence reactive current command two-dimensional droop parameter Two-dimensional droop parameters of negative sequence voltage-positive sequence reactive current command Initial value of negative sequence reactive current command Two-dimensional droop parameters of positive sequence voltage-negative sequence reactive current command Two-dimensional droop parameters of negative sequence voltage-negative sequence reactive current command .

6. The method for active power support during fault ride-through of new energy power stations based on two-dimensional droop-layered control according to claim 5, characterized in that, In the alternating iterative solution process of steps S3 and S4, the worst-case fault condition is determined. The iteration termination is determined by the per-unit values ​​of various physical stresses of the converter calculated based on the upper limit of stress; if the worst-case fault condition is... The per-unit values ​​of all physical stresses of the converter, based on the upper limit of stress, are all less than or equal to the normalized threshold constant. If the value is 1.0, the alternating iterations terminate, and the globally convergent two-dimensional droop parameter matrix is ​​output. .

7. The method for active power support during fault ride-through of new energy power stations based on two-dimensional droop-layered control according to claim 1, characterized in that, Device-level control is based on a two-dimensional droop parameter matrix Constructing a two-dimensional droop surface for current commands and implementing fault ride-through control based on the two-dimensional droop surface for current commands, step S5 includes calling the two-dimensional droop parameter matrix. The spatial coordinates of the top edge nodes of the two-dimensional drooping surface under the current command are clearly defined, and the spatial surface is established by two-dimensional mesh interpolation fitting. The method for calculating the spatial coordinates of top-level edge nodes includes setting the positive sequence voltage amplitude at the grid connection point of the substation during fault ride-through. The upper and lower limits of the change and the negative sequence voltage amplitude at the grid connection point of the power station The upper and lower limits of the variation are combined to form a limit phasor coordinate system and substituted into the two-dimensional droop parameter matrix. The characteristic equation is used to obtain the current command output value corresponding to the limit phasor coordinate system.

8. The method for active power support during fault ride-through of new energy power stations based on two-dimensional droop-layered control according to claim 7, characterized in that, The characteristic equation for the control command corresponding to the two-dimensional drooping surface output based on the current command is calculated algebraically as follows: Station positive sequence active current command Used to support active power output; Power station positive sequence reactive current command It is used to support positive sequence voltage and indirectly improve active power output; Station negative sequence reactive current command This is used to reduce voltage asymmetry at the grid connection point; At the same time, the negative sequence active current command is forcibly set to zero in the equipment-level control stage.

9. The method for active power support during fault ride-through of new energy power stations based on two-dimensional droop-layered control according to claim 1, characterized in that, Step S6, the fault rapid response process based on hierarchical control, specifically includes: the converter equipment-level control calls the local voltage transformer to monitor the measured grid-side voltage signal, and the positive sequence voltage amplitude at the substation grid connection point is obtained after decoupling through a second-order generalized integrator phase-locked loop module. Negative sequence voltage amplitude at the grid connection point of the power station The decoupling result is mapped into the two-dimensional drooping surface of the current command, and the instantaneous reference current command signal is retrieved and sent to the underlying pulse width modulator of the power generation equipment to perform the injection action.

10. The method for active power support during fault ride-through of new energy power stations based on two-dimensional droop-layered control according to claim 1, characterized in that, The new energy power station fault ride-through active power support method based on two-dimensional drooping hierarchical control actively blocks the negative sequence active current during the fault period. The instruction generation stage forces the negative sequence active current of the power station to be a zero per-unit constant in order to reduce the second harmonic power oscillation caused by the current output of the power station.

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