A method and apparatus for co-reshaping broadband impedance of wind farms

Abstract

This invention pertains to the field of power and discloses a method and apparatus for the collaborative reshaping of broadband impedance in wind farms. The method includes: constructing a global node broadband admittance matrix model considering the distributed capacitance effect of the lines; extracting the equivalent short-circuit ratio of each electrical node within the wind farm using the Kron algorithm for reducing the admittance matrix order and eliminating variables; reshaping the broadband impedance characteristics of heterogeneous power generation units within the wind farm by combining the node equivalent short-circuit ratio and the physical constraints of the converter equipment through differentiated tiered tuning of control parameters and phase-frequency characteristic compensation; and coordinating control strategies across frequency bands and reconstructing the equivalent frequency domain impedance characteristics and oscillation modes of the global broadband admittance network of the wind farm to achieve the collaborative reshaping of the wind farm's full-band broadband impedance.

Description

Technical Field

[0001] This invention belongs to the field of power, and particularly relates to a method and apparatus for the collaborative reshaping of broadband impedance in wind farms. Background Technology

[0002] With the large-scale construction and development of wind farms, the distributed capacitance effect of lines within the wind farms has significantly increased, and the dynamic characteristics of multi-source heterogeneous converters are complex and diverse. A large number of heterogeneous wind turbines and energy storage converters are connected to the weak power grid through collector lines, resulting in a significant spatial gradient in the equivalent short-circuit ratio of each node within the wind farm. Against this backdrop, the broadband impedance characteristics of different types of converters may exhibit negative damping ranges in low-frequency, sub-supersynchronous, and high-frequency bands. When the control parameters of multiple units converge, the resonant modes of the same frequency couple and superimpose between nodes, posing a risk of broadband oscillation instability and seriously threatening the safe and stable operation of the wind farm.

[0003] Existing broadband oscillation suppression methods mainly focus on the level of a single converter or similar types: first, by adjusting control parameters such as the phase-locked loop bandwidth and the cutoff frequency of the inner current loop of a single converter to improve impedance phase margin; second, for high-frequency resonance, methods such as active damping or LCL filter parameter optimization are used; and third, for low-frequency oscillation, the virtual inertia and damping coefficient of the grid-connected units are adjusted. However, the above methods generally have the following shortcomings: first, they lack a systematic understanding of the differences in the global node network topology of wind farms and the heterogeneous characteristics of the units, ignoring the key impact of line distributed capacitance on broadband admittance characteristics; second, the control parameter tuning lacks an adaptive mechanism driven by the node grid strength, making it difficult to guarantee stability margin across the entire frequency band when the grid strength changes dynamically; and third, most existing methods are designed independently for a single frequency band, failing to achieve coordinated suppression of low-frequency, sub-supersynchronous, and high-frequency multi-band oscillation modes.

[0004] In practical engineering, wind power collection stations often include a variety of heterogeneous units, such as grid-type energy storage converters and near-end and far-end grid-connected converters. The switching frequencies, filter parameters and control bandwidths of the various units are different, and the equivalent short-circuit ratios of each node show a significant spatial gradient distribution due to the different lengths of the collector lines. Summary of the Invention

[0005] In view of this, the present invention discloses a method and apparatus for the collaborative reshaping of broadband impedance in wind farms, which can solve the shortcomings of related technologies.

[0006] To achieve the above objectives, the present invention discloses the following technical solution: According to a first aspect of the present invention, a method for the collaborative reshaping of broadband impedance in wind farms is proposed, comprising: A global node broadband admittance matrix model considering the distributed capacitance effect of the line is constructed, and the equivalent short-circuit ratio of each electrical node in the field is extracted by the Krohn reduction and elimination algorithm of the admittance matrix. Based on the equivalent short-circuit ratio of the nodes and the physical constraints of the converter equipment, the wide-band impedance characteristics of the heterogeneous power generation units in the wind farm are reshaped through differentiated tiered tuning of control parameters and phase frequency characteristic compensation. In the low-frequency band, for grid-type units, the impedance characteristics in the low-frequency band are actively reshaped by symmetrically injecting the frequency band adaptive transient active conductance into the main diagonal elements of the voltage control loop transfer function matrix in the dq rotating coordinate system. In the sub-supersynchronous frequency band and intermediate frequency band, for various heterogeneous grid-type converter equipment containing heterogeneous grid-type units and static var generators, the impedance characteristics of the sub-supersynchronous frequency band and intermediate frequency band are reshaped by adjusting the phase-locked loop closed-loop bandwidth and low-pass filter cutoff frequency in a stepped distribution. In the high-frequency band, for heterogeneous units, an asymmetric zero-pole phase correction stage is introduced. By controlling the delay and high-frequency damping, the zero-pole corner frequency is established respectively, and the impedance phase frequency characteristics in the high-frequency band are reshaped in a directional manner. By coordinating control strategies across frequency bands and reconstructing the equivalent frequency domain impedance characteristics and oscillation modes of the global broadband admittance network of the wind farm, the synergistic reshaping of the broadband impedance across the entire frequency band of the wind farm can be achieved.

[0007] According to a second aspect of the present invention, a collaborative reshaping device for broadband impedance of a wind farm is provided, comprising: Construction Unit: Construct a global node broadband admittance matrix model that takes into account the distributed capacitance effect of the line, and extract the equivalent short-circuit ratio of each electrical node in the field through the Krohn reduction and elimination algorithm of the admittance matrix; Tuning Unit: Based on the equivalent short-circuit ratio of the nodes and the physical constraints of the converter equipment, the wide-band impedance characteristics of the heterogeneous power generation units in the wind farm are reshaped through differentiated tiered tuning of control parameters and phase frequency characteristic compensation. First reshaping unit: In the low-frequency band, for grid-type units, the impedance characteristics in the low-frequency band are actively reshaped by symmetrically injecting the frequency band adaptive transient active conductance into the main diagonal elements of the voltage control loop transfer function matrix in the dq rotating coordinate system. The second reshaping unit: In the sub-supersynchronous frequency band and intermediate frequency band, for each heterogeneous and heterogeneous grid-type converter equipment containing heterogeneous grid-type units and static var generators, the impedance characteristics of the sub-supersynchronous frequency band and intermediate frequency band are reshaped by adjusting the phase-locked loop closed-loop bandwidth and low-pass filter cutoff frequency in a stepped distribution. The third reshaping unit: In the high-frequency band, for heterogeneous units, an asymmetric zero-pole phase correction stage is introduced. By controlling the delay and high-frequency damping, the zero-pole corner frequency is established respectively, and the impedance phase frequency characteristics in the high-frequency band are reshaped in a directional manner. Coordination Unit: Coordinates control strategies across frequency bands and reconstructs the equivalent frequency domain impedance characteristics and oscillation modes of the global broadband admittance network of the wind farm to achieve coordinated reshaping of the broadband impedance across the entire frequency band of the wind farm.

[0008] According to a third aspect of the present invention, an electronic device is provided, comprising: processor; Memory used to store processor-executable instructions; The processor implements the steps of the method as described in the first aspect by running the executable instructions.

[0009] According to a fourth aspect of the invention, a computer-readable storage medium is provided having computer instructions stored thereon that, when executed by a processor, implement the steps of the method as described in the first aspect.

[0010] As can be seen from the above technical solutions, the beneficial effects of the wind farm broadband impedance co-reshaping method and device disclosed in this invention are as follows: 1. This invention proposes using the equivalent short-circuit ratio (ESCR) of nodes as a unified quantitative index for broadband impedance optimization tuning, and employs the Kron algorithm for admittance matrix reduction and elimination to evaluate the grid strength of each electrical node within the wind farm. Compared to the traditional method that only uses the short-circuit ratio at the point of connection (PCC) to characterize system strength, this invention can more accurately depict the spatial gradient differences in broadband impedance characteristics of each bus node within the wind farm, thereby effectively guiding the spatial and frequency domain differentiated tiered configuration of control parameters for heterogeneous units within the farm, and achieving broadband impedance collaborative optimization from a global perspective.

[0011] 2. This invention addresses the risk of low-frequency oscillations by proposing a transient active conductance adaptive reshaping mechanism for grid-connected generating units. Utilizing the proportional mapping between the grid-connected system's resonant frequency and the square root of the equivalent short-circuit ratio, it achieves automatic tracking and alignment of the bandpass filter's frequency band as the grid strength shifts. Simultaneously, it dynamically updates the gain based on the inverse relationship between the station's equivalent impedance and the equivalent short-circuit ratio. In the dq rotating coordinate system, positive damping is introduced through a decoupled symmetrical main diagonal injection method. Compared to traditional fixed-parameter damping control, this mechanism provides robust damping enhancement under large variations in grid strength, actively reshaping the low-frequency impedance characteristics and suppressing the risk of low-frequency power oscillation instability.

[0012] 3. This invention addresses the multi-unit interactive resonance problem by proposing a frequency reshaping strategy where the cutoff frequencies of the phase-locked loops and low-pass filters of grid-connected wind turbines are distributed in a tiered manner. Utilizing the difference in line spatial impedance, the equivalent wideband admittance response characteristic frequencies of heterogeneous wind turbine clusters connected in parallel to the same busbar are staggered in the complex frequency domain within the sub-supersynchronous and mid-frequency bands. This method can suppress the co-frequency resonance coupling amplification effect caused by the convergence of parameters among multiple units and weaken the negative damping oscillation energy interaction in the sub-supersynchronous and mid-frequency bands.

[0013] 4. This invention addresses high-frequency resonant instability modes by proposing an asymmetric zero-pole phase correction mechanism based on a dual independent constraint rule. By deeply analyzing the phase lag difference introduced by the discrete control delay at the bottom layer of heterogeneous wind turbine units, and considering the high-frequency damping margins provided by the skin effect and core eddy current effect, the zero-point and pole parameters are independently tuned. This technique directionally reshapes the impedance phase-frequency characteristics in the high-frequency range, improving the high-frequency broadband passivity above the critical frequency. Simultaneously, its proportional design principle ensures the universality of the unified correction rule for units with different switching frequencies, reducing the engineering implementation complexity of multi-unit coordinated tuning in large-scale wind farms.

[0014] 5. This invention achieves closed-loop collaborative reshaping of impedance across the entire frequency band. It integrates three strategies: active reshaping in the low-frequency band, sub-supersynchronous and mid-frequency band frequency misalignment reshaping, and directional reshaping in the high-frequency band. Under the framework of a global wideband admittance matrix, the closed-loop characteristic equation of the station is jointly reconstructed, resulting in the smoothing of resonant amplification peaks at local oscillation nodes, a more gradual wideband distribution of wideband admittance characteristics, and improved global wideband stability margin of the station. Attached Figure Description

[0015] Figure 1 This is a flowchart of a method for collaborative reshaping of broadband impedance in a wind farm, provided in an exemplary embodiment. Figure 2 This is a schematic diagram of a heterogeneous converter grid-connected system topology for conducting computational verification, provided in an exemplary embodiment. Figure 3 This is a schematic diagram of an adaptive slip curve of a key parameter of transient active conductance as a function of the equivalent short-circuit ratio, provided in an exemplary embodiment. Figure 4 This is a schematic diagram of a GFM grid-type converter control structure provided in an exemplary embodiment; Figure 5 This is a schematic diagram of a GFL-based grid-connected wind turbine converter control structure provided in an exemplary embodiment; Figure 6 This is a schematic structural diagram of a device provided in an exemplary embodiment; Figure 7This is a block diagram of a wind farm broadband impedance co-reshaping device provided in an exemplary embodiment. Detailed Implementation

[0016] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with one or more embodiments of the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of one or more embodiments of the present invention as detailed in the appended claims.

[0017] It should be noted that the steps of the corresponding methods in other embodiments are not necessarily performed in the order shown and described in this invention. In some other embodiments, the methods may include more or fewer steps than those described in this invention. Furthermore, a single step described in this invention may be broken down into multiple steps in other embodiments; and multiple steps described in this invention may be combined into a single step in other embodiments.

[0018] To address the shortcomings of traditional methods, this invention proposes a collaborative reshaping method and apparatus for broadband impedance of wind farms.

[0019] Figure 1 This is a flowchart illustrating a method for collaborative reshaping of broadband impedance in a wind farm, as provided in an exemplary embodiment. Figure 1 As shown, the method may include the following steps: Step 101: Construct a global node broadband admittance matrix model that takes into account the distributed capacitance effect of the line, and extract the equivalent short-circuit ratio of each electrical node in the field through the Kron algorithm for reducing the order of the admittance matrix.

[0020] The construction of a global node broadband admittance matrix model considering the distributed capacitance effect of the line, and the extraction of the equivalent short-circuit ratio of each electrical node in the field through the Krohn reduction and elimination algorithm of the admittance matrix, includes: integrating the dynamic characteristics of the multi-source heterogeneous converter and the distributed capacitance effect of the line, and introducing a frequency-varying damping coefficient to correct the high-frequency equivalent impedance to establish a global node broadband admittance matrix model; according to the Krohn reduction and elimination algorithm of the admittance matrix, extracting the electrical coupling correlation matrix from the remote grid connection point to each electrical node in the field, and quantitatively analyzing the features into the node equivalent short-circuit ratio.

[0021] Specifically, step 101 includes: Step 1.1: Establish the branch series impedance matrix with frequency-varying skin effect correction in the dq rotating coordinate system. For the collector line and transformer winding, introduce a frequency-varying skin effect correction coefficient. Dynamic correction of branch resistance: ; In the formula, f0 = 50 Hz is the fundamental frequency of the grid-connected system, α is the skin effect exponent, α = 0.50 for solid stranded conductors, α = 0.30 for CTC windings of transformer cores, and α = 0.40 for foil windings. The corresponding branch series impedance matrix in the dq rotating coordinate system is: ; In the formula, R and X are the per-unit values ​​of the branch power frequency resistance and reactance, respectively, s = jω is the complex frequency variable, and ω0 = 2πf0 is the reference angular frequency of the grid-connected system.

[0022] Step 1.2: Establish a global broadband admittance matrix for the pure passive network, taking into account the distributed capacitance effect of the line, in the dq rotating coordinate system. Based on the branch impedance matrix with skin effect correction established in Step 1.1, assemble passive network components such as collector lines, transformers, and distributed capacitance of the line into a station node admittance matrix. Use the Kron algorithm for admittance matrix reduction and elimination to successively eliminate internal nodes, effectively reducing the original large-dimensional pure passive network admittance matrix to a low-dimensional broadband equivalent admittance matrix that retains only the nodes of interest to the grid. The reduction formula is as follows: ; In the formula, Let be the equivalent self-admittance matrix of node b after order reduction. The self-admittance block is the node b of the original admittance matrix. The mutual admittance between node b and the set of nodes to be eliminated is divided into blocks. For the self-indulgent partitioning of the set of nodes e to be eliminated, This is the transpose of the mutual admittance block.

[0023] Step 1.3: Based on the node admittance matrix of the pure passive network established in Step 1.2, the small-signal equivalent admittances of each grid-connected converter are superimposed onto the corresponding nodes to form a global active node admittance matrix containing the small-signal dynamics of all grid-connected converters. After inverting the matrix, the main diagonal elements of the self-impedance of node b are taken. That is, the port equivalent impedance of node b (also known as the node equivalent impedance), and then the node equivalent short-circuit ratio (ESCR) is calculated: ; In the formula, The main diagonal element of the port equivalent self-impedance of node b after inverting the global active node admittance matrix containing the small-signal equivalent admittance contribution of all converters in the station, i.e. the broadband equivalent impedance seen from the port of node b, where |·| represents the modulus of the complex number. The difference between the ESCR and the traditional grid-connected point short-circuit ratio (SCR) in this invention lies in the fact that the traditional SCR is based solely on passive grid impedance calculations, while the ESCR in this invention is based on the equivalent impedance calculation of the global active node admittance matrix, which includes the small-signal equivalent admittance of all converters within the substation. This takes into account the contribution of converter dynamics to the node's electrical strength, and thus more accurately reflects the actual stability margin when multiple types of converters are connected to the grid. A smaller ESCR indicates weaker electrical strength at the node, making it more prone to broadband oscillation instability. Extracting the equivalent short-circuit ratio of all nodes of interest provides a basis for the differentiated tiered tuning of control parameters and phase-frequency characteristic compensation for subsequent frequency bands.

[0024] Based on the aforementioned global node broadband admittance matrix model, three layers of resonant frequency systems are identified within the wind farm: the first is global network resonance, determined by the parallel connection of the equivalent inductance from the busbar to the power supply side and the distributed capacitance of all collector lines. This resonant frequency drifts with changes in the equivalent short-circuit ratio at the grid connection point and is most sensitive to the broadband stability of the site. The second is local resonance in each branch, determined by the series inductance of the box-type transformer and the collector lines in each branch, along with the distributed capacitance of the branch. This frequency is higher than the global network resonance and is not sensitive to the equivalent short-circuit ratio. The third is resonance of the LCL filter of a single converter, determined only by the local filter parameters and independent of the network topology.

[0025] Step 1.4: To comprehensively characterize the sequence component characteristics of the broadband admittance at each node, the 2×2 admittance matrix in the dq coordinate system is decoupled and transformed into positive-sequence and negative-sequence admittances. The positive-sequence admittance Ypos reflects the dynamic response characteristics of the converter to positive-sequence disturbances; its real part characterizes positive damping and is the core indicator for judging the broadband stability of each frequency band. The negative-sequence admittance Yneg reflects the asymmetric response characteristics. This transformation decouples the dq coupling matrix into two independent scalars, reducing the computational complexity of broadband stability analysis.

[0026] Step 102: Based on the equivalent short-circuit ratio of the nodes and the physical constraints of the converter equipment, the wide-band impedance characteristics of the heterogeneous power generation units in the wind farm are reshaped through differentiated tiered tuning of control parameters and phase frequency characteristic compensation.

[0027] The differentiated tiered tuning of control parameters and phase-frequency characteristic compensation include: implementing coordinated tuning of control parameters for frequency bands in conjunction with the hardware switching frequency limitation of heterogeneous converters; identifying potential co-frequency resonance risk bands at the station level under the global admittance and matrix framework; and implementing tiered allocation of control response bandwidth for each grid-connected converter based on the spatial gradient of the equivalent short-circuit ratio of each electrical node in the field, with lower current inner loop and phase-locked loop closed-loop bandwidths set for lower equivalent short-circuit ratio nodes.

[0028] Specifically, such as Figure 2As shown, the wind farm topology in this example includes 7 grid-connected nodes of interest (nodes 1 to 7). Nodes 1 and 2 are GFM-type grid-connected energy storage converter access nodes; nodes 3 and 4 are GFL-N near-end grid-connected wind turbine converter access nodes; nodes 5 and 6 are GFL-F far-end grid-connected wind turbine converter access nodes; and node 7 is the SVG static var generator access node connected to the 220 kV high-voltage bus. The equivalent short-circuit ratios (ESCRs) of each node exhibit a significant spatial gradient: ESCR ≈ 1.400 for the far-end PCC node, ESCR ≈ 1.261 for the 220 kV high-voltage bus, ESCR ≈ 1.182 for the 35 kV medium-voltage bus, and ESCR for the GFL-F far-end wind turbine terminal node is approximately 0.9~1.0.

[0029] Step 102 includes: Step 2.1: Identify potential co-frequency resonance risk bands at the site level within the framework of the global nodal broadband admittance matrix. Based on the global broadband admittance matrix constructed in Step 1, calculate the site-level closed-loop characteristic equation: The approximate root locus is used to identify the distribution location of the admittance response peaks in each frequency band. When the equivalent admittance responses of multiple parallel-operated converters are superimposed in the same direction at a certain frequency point, that is, when the equivalent admittance responses of multiple units are superimposed in the same direction, the distribution location of the peak admittance responses is determined. When the real part of the positive-sequence admittance Re[Ypos] is negative and has a similar amplitude at the same frequency, the frequency is determined to be a potential co-frequency resonance risk band, and the corresponding oscillation mode has a risk of coupling amplification between nodes.

[0030] Step 2.2: Based on the spatial gradient distribution of the equivalent short-circuit ratio of each electrical node in the field, implement a tiered allocation of control response bandwidth for each heterogeneous and grid-type converter. For branch nodes with lower equivalent short-circuit ratios and electrical locations closer to the end of the collector line, coordinately set lower current inner loop closed-loop bandwidth ωc,CC and phase-locked loop closed-loop bandwidth ωn,PLL to make the converter at that node... The response peak shifts towards lower frequencies, achieving frequency domain decoupling from the near-end node converter with a higher equivalent short-circuit ratio, thus fundamentally suppressing the superposition effect of co-frequency coupling caused by convergent control parameters. Specifically, during tuning, the switching frequency of various converter hardware is considered. Apply an upper limit constraint to the control bandwidth: ; Ensure that the tuning parameters are within the converter hardware constraints.

[0031] Combination Figure 2The specific tuning parameters are as follows: The switching frequency of the GFM grid-connected energy storage converter is 2000 Hz, corresponding to nodes 1 and 2, with a collector line length of 0.5 km and an inner current loop cutoff frequency of 200 Hz. The switching frequency of the GFL-N near-end grid-connected wind turbine converter is 2000 Hz, corresponding to nodes 3 and 4, with collector line lengths of 2.5 km and 4.0 km, respectively. The node equivalent short-circuit ratio is high, the inner current loop cutoff frequency is set to 200 Hz, the phase-locked loop natural frequency is set to 8 Hz (corresponding to a closed-loop bandwidth of approximately 18.0 Hz), and the feedforward low-pass filter cutoff frequency is set to 100 Hz. The switching frequency of the GFL-F far-end grid-connected wind turbine converter is 1500 Hz, corresponding to nodes 5 and 6, with collector line lengths of 8.0 km and 12.0 km, respectively. The node equivalent short-circuit ratio is low, the inner current loop cutoff frequency is set to 150 Hz, and the phase-locked loop natural frequency is set to 5 Hz. The switching frequency of the SVG static var generator is 2000Hz, corresponding to node 7, which has the highest equivalent short-circuit ratio. The natural frequency of the phase-locked loop (PLL) is set to 15Hz (corresponding to a closed-loop bandwidth of approximately 34Hz), and the cutoff frequency of the feedforward low-pass filter is set to 110Hz. The closed-loop bandwidths of the three types of grid-connected converters, from high to low, are 34Hz, 18.0Hz, and 10.3Hz, respectively, and the cutoff frequencies of the feedforward low-pass filters, from high to low, are 110Hz, 100Hz, and 90Hz, respectively. The decoupling of the control frequency domain is achieved by utilizing the difference in spatial impedance.

[0032] The specific setting parameters of each device are determined based on the equivalent short-circuit ratio of its access node and the switching frequency. The difference in spatial impedance is used to achieve decoupling of the control frequency domain and avoid the resonance amplification effect caused by the superposition of heterogeneous units in the same frequency band.

[0033] Step 103: In the low-frequency band, for grid-type units, the impedance characteristics in the low-frequency band are actively reshaped by symmetrically injecting the frequency band adaptive transient active conductance into the main diagonal elements of the voltage control loop transfer function matrix in the dq rotating coordinate system.

[0034] The equivalent short-circuit ratio is sensed in real time, and a frequency band adaptive following and gain dynamic optimization algorithm for the transient control branch is constructed. The cutoff frequency of the bandpass filter is biased in the frequency domain according to the square root ratio of the equivalent short-circuit ratio and the preset reference short-circuit ratio, so that the bandpass frequency band slides synchronously with the grid strength. The transient active conductance gain is dynamically updated according to the inverse relationship between the equivalent short-circuit ratio and the reference short-circuit ratio. The gain is cascaded with the bandpass filter to generate a transient active conductance component, which is symmetrically injected into the main diagonal elements of the voltage outer loop control matrix of the grid-type unit in the dq rotating coordinate system.

[0035] Specifically, step 103 includes: Step 3.1: Real-time sensing of the equivalent short-circuit ratio of nodes, and constructing a frequency band adaptive following algorithm based on the following physical laws: the resonant frequency of the grid-connected system is directly proportional to the square root of the equivalent short-circuit ratio, and the equivalent impedance of the grid-connected system is inversely proportional to the equivalent short-circuit ratio. The lower cutoff angular frequency of the bandpass filter (BPF). and upper limit cutoff angular frequency The adaptive tuning formula is as follows: ; In the formula, and These are the design baseline values ​​for the lower and upper cutoff angular frequencies of the bandpass filter under the baseline equivalent short-circuit ratio ESCR0, where ESCR is the real-time sensed node equivalent short-circuit ratio and ESCR0 is the preset baseline equivalent short-circuit ratio. When the grid strength decreases, the filter passband shifts overall towards lower frequencies to track weak resonant frequency bands.

[0036] Step 3.2: Based on the linear inverse relationship between the equivalent short-circuit ratio and the preset benchmark, dynamically update the transient active conductance gain. : ; In the formula, This is the reference gain.

[0037] Step 3.3: Construct the transfer function of the bandpass selective filter: ; Step 3.4: Adjust the dynamic gain Cascaded with a bandpass filter GBPF(s), it forms a transient active conductance transfer function. = The GBPF(s) is then superimposed onto the proportional-integral controller of the outer voltage loop of the grid-connected unit to form the effective voltage control transfer function. : ; Step 3.5: In the dq rotating coordinate system, the transient active conductance is symmetrically injected into the main diagonal elements of the voltage control loop transfer function matrix in a decoupled superposition manner to ensure the synchronous improvement of d-axis and q-axis damping without introducing cross-coupling components. ; This diagonal symmetrical injection structure helps maintain independent damped injection of active and reactive power channels in the dq coordinate system, avoiding additional cross-coupling interference introduced by off-diagonal elements, thereby enabling the positive damping frequency band of the grid-type unit to effectively track and cover the weak resonant frequency band that drifts with the grid strength.

[0038] Step 3.6: Establish the complete small-signal admittance matrix of the grid-connected generator (GFM) with transient active conductance, and its control structure is as follows. Figure 3 As shown. Taking the small-signal quantities of port voltage and port current in the dq rotating coordinate system as port variables, they are defined as follows: ;

[0039] In the formula, the first row To introduce the equivalent control matrix of the voltage outer loop after transient active conductance, a pure diagonal structure is used to ensure strict decoupling of the dq axis channels. The transient active conductance transfer function is adaptively updated with the equivalent short-circuit ratio; line 2 The forward matrix is ​​a joint forward matrix of current inner loop - voltage outer loop - virtual impedance - QV droop, where This is a diagonal matrix of the inner current loop containing digitally controlled delays. To measure the low-pass filter, The decoupling matrix for the dq axis. For virtual impedance matrix, and This is the coupling transfer matrix of QV droop to the current path and voltage path; row 3. This is the forward transfer matrix from voltage to internal current. For the feedforward transfer matrix, This is the active damped virtual impedance containing an asymmetric zero-pole phase correction element. This is the admittance matrix of the filter capacitor; row 4. The equivalent admittance inside the converter; line 5 Superimposed filter capacitors; line 6 The power-angle coupling correction matrix introduced by the oscillation equation consisting of virtual inertia J and virtual damping D and ; 7th row via series grid side reactor Impedance of box-type transformer Multiply by the number of parallel-operating units N at that node, the ratio of the rated capacity of a single unit to the system baseline capacity (capacity normalization factor) κ = Srated / Sbase, and the coordinate rotation matrix. This allows for direct integration into the global broadband admittance matrix of the site. .

[0040] The elements are determined by the steady-state phase-locked angle θ of the converter: ; Transient active conductance is achieved by increasing the first row. The main diagonal element makes The real part of the positive sequence admittance increases near the bandpass center frequency, which is equivalent to injected positive damping conductance, actively reshaping the impedance characteristics in the low-frequency band, and strictly does not introduce cross-coupling between the dq axes.

[0041] like Figure 3 As shown, the baseline values ​​for each parameter are set as follows: baseline equivalent short-circuit ratio ESCR0 = 1.5, baseline gain Kσ0 = 0.42, the baseline value of the lower cutoff angular frequency ωL,0 corresponds to the frequency fL,0 = 0.05 Hz, and the baseline value of the upper cutoff angular frequency ωH,0 corresponds to the frequency fH,0 = 5.0 Hz. Taking the current example with an equivalent short-circuit ratio ESCR = 1.4, substituting the above baseline values ​​into the adaptive formula for transient active conductance, we obtain: ; like Figure 4 As shown, the transient active conductance is superimposed on the PI control matrix of the outer loop of the GFM voltage in a main diagonal manner to achieve dq axisymmetric injection without introducing cross coupling. The complete small-signal admittance matrix of the GFM is established and converted to the global stationary coordinate system after coordinate rotation.

[0042] Step 104: In the sub-supersynchronous frequency band and intermediate frequency band, for each heterogeneous grid-type converter equipment containing heterogeneous grid-type units and static var generators, the impedance characteristics of the sub-supersynchronous frequency band and intermediate frequency band are reshaped by adjusting the phase-locked loop closed-loop bandwidth and low-pass filter cutoff frequency in a stepped distribution.

[0043] For heterogeneous and grid-type converter equipment clusters connected in parallel to the same bus or with strong electrical coupling correlation, the cutoff frequency of the low-pass filter and the closed-loop bandwidth of the phase-locked loop of each equipment are determined according to the equivalent short-circuit ratio and electrical coupling correlation of each equipment node, with a fixed frequency difference margin, so that the equivalent wideband admittance response characteristic frequency points of the cluster in the sub-supersynchronous frequency band and the intermediate frequency band are staggered in the complex frequency domain.

[0044] Specifically, step 104 includes: Step 4.1: Establish the complete small-signal admittance matrix of the grid-connected converter (GFL) (control structure as follows) Figure 5 As shown in the figure, the influence mechanism of the phase-locked loop bandwidth and the low-pass filter cutoff frequency on the impedance characteristics of the sub-supersynchronous band is revealed, and the derivation of the equation set is as follows: and Together, they constitute a heterogeneous broadband impedance modeling system within the station. The complete derivation of the equations is as follows: ; ; In the formula, the first row The closed-loop transfer function of the phase-locked loop (PLL) determines the coupling characteristics in the subsynchronous frequency band by determining the pole locations. Lowering the natural frequency of the PLL causes the poles to shift to lower frequencies. (Line 2) This is a joint forward matrix for feedforward and DC voltage control. For the feedforward transfer matrix, This is the coupling matrix of the DC link to the voltage path, with elements determined by the steady-state operating point currents Id0 and Iq0 and the DC dynamic gain Kdc; (Row 3) It is a current inner loop-phase-locked loop-DC dynamic joint transfer matrix. For DC dynamic coupling, This is the decoupling matrix for the dq axis; row 4. Here is the voltage-to-current forward transfer matrix, where , The coupling matrix introduced by the phase-locked loop through the steady-state operating point has only the second column being non-zero, reflecting the physical nature of the PLL only sensing the q-axis voltage error; This is the PLL coupling term for the steady-state operating point of the modulation voltage; For the active damped virtual impedance containing an asymmetric zero-pole phase correction element; line 5 The equivalent admittance inside the converter; line 6 Superimposed filter capacitor; Reactance on the series grid side in row 7 Impedance of box-type transformer Capacity normalization coefficient and coordinate rotation matrix ,have to Based on the equivalent short-circuit ratio spatial gradient, different phase-locked loop bandwidths are set for each type of converter, so that each device... The peak frequencies of the responses are staggered in the complex frequency domain, which reduces the risk of multi-machine co-frequency coupling resonance.

[0045] Step 4.2: For each grid-type converter connected in parallel to the same busbar or with strong electrical coupling, based on the equivalent short-circuit ratio and electrical coupling of each device node, adjust the closed-loop bandwidth of the phase-locked loop and the cutoff frequency of the low-pass filter with a fixed frequency margin, so that the equivalent wideband admittance response characteristic frequencies of each device are staggered in the complex frequency domain. For grid-connected converters, including grid-connected wind turbine converters and static var generators, based on the evaluation results of the equivalent short-circuit ratio of each device node, the closed-loop bandwidth of the phase-locked loop and the cutoff frequency of the feedforward low-pass filter of each device are pre-designed so that the characteristic frequency points of each device are distributed in a stepped manner in the complex frequency domain. After the parameters are fixed, no online dynamic adjustment is required. The tuning rules are as follows:

[0046]

[0047] In the formula, and These are the closed-loop bandwidth of the phase-locked loop and the reference value of the low-pass filter cutoff frequency of the k-th device, respectively. and For a fixed frequency margin, N is the number of units in the cluster.

[0048] The specific parameters are as follows: fPLL,1=34 Hz, ΔfPLL=8 Hz; fLPF,1=110 Hz, ΔfLPF=10 Hz; N=3. The characteristic frequency points of the three types of equipment are staggered in the complex frequency domain, which effectively weakens the negative damping oscillation energy interaction loop in the sub-supersynchronous frequency band and the intermediate frequency band.

[0049] Step 105: In the high-frequency band, for heterogeneous units, an asymmetric zero-pole phase correction stage is introduced. By controlling the delay and high-frequency damping, the zero-pole corner frequency is established respectively, and the impedance phase frequency characteristics in the high-frequency band are reshaped in a directional manner.

[0050] The phase correction stage is placed only in the active damping virtual impedance path and is not superimposed on the main current control loop. The zero-point corner frequency is independently tuned according to the discrete control delay of each heterogeneous converter to provide phase lead compensation. The pole corner frequency is independently tuned with the high-frequency damping margin as the upper limit constraint to suppress high-frequency gain amplification, forming a wideband phase correction stage with asymmetrical distribution of zeros and poles in the frequency domain.

[0051] Specifically, step 105 includes: Step 5.1: Based on the discrete control delay of each heterogeneous converter, the zero-point corner frequency is tuned according to the phase correction design criteria to provide phase lead compensation; the pole corner frequency is tuned with the high-frequency line damping margin as the upper limit constraint to suppress high-frequency gain amplification, thereby forming an asymmetric distributed broadband phase correction stage, the transfer function of which is as follows: The phase lag introduced by discrete sampling and PWM modulation in digital control systems can be equivalent to a delay element, and this phase lag is particularly significant at high frequencies. The transfer function of the lead-lag compensator is defined as follows: ; In the formula, and These are the corner frequencies of the zeros and poles of the compensator, respectively, satisfying... This means that the zero-point frequency is lower than the pole frequency, resulting in phase lead compensation. During the tuning process, in addition to the phase lag introduced by the analytical discrete control delay, the physical characteristics of the high-frequency line equivalent resistance increasing with frequency due to the skin effect and the additional loss damping provided by the core eddy current effect are also considered. The line damping margin is used as the upper limit of the active compensation bandwidth to avoid excessive extension of the compensation bandwidth into the already sufficiently damped frequency band, thus injecting active negative damping components. The zero-pole corner frequencies of various converters are determined according to the above dual independent constraint law and are fixedly configured in each converter controller, without relying on online solutions.

[0052] Step 5.2: Verify that the phase correction parameters of various converters ensure that the equivalent source impedance meets the full-band broadband passive condition. The goal of high-frequency active damping phase compensation is to ensure that the equivalent impedance satisfies the broadband passive condition across the entire frequency band, i.e., the phase angle of the equivalent source impedance is constrained to the passive region. ; This condition is equivalent to That is, the real part of the impedance is non-negative, and the source side is equivalent to a passive network. Through the reverse matching tuning of the above-mentioned asymmetric zero-pole lead-lag compensator, the impedance phase angle of various converters in their respective key high-frequency bands is pulled back to the passive range, reducing the possibility of high-frequency resonance excitation from a mechanism level.

[0053] The control parameters for various converters follow a proportional design principle. Substituting the switching frequencies of various converters, the specific tuning parameters are as follows: ; ; ; ; ; As can be seen from the above proportionality criterion, the phase lag of the main control path of various converters at their respective broadband impedance analysis upper limit frequency is φmain=-216° and the phase lag of the active damping path is φad=-72°, which are independent of the switching frequency, thus ensuring the universality of the unified design criterion.

[0054] Step 5.1 Adjust the lead-lag compensator parameters for various converters according to the phase correction design criteria: For the GFM grid-type converter, the zero-point frequency fz = 536 Hz, and the pole frequency fp, GFM = 1600 Hz; for the GFL-N near-end grid-type wind turbine converter, the zero-point frequency fz = 389 Hz, and the pole frequency fp, GFL-N = 1600 Hz; for the GFL-F far-end grid-type wind turbine converter, the zero-point frequency fz = 381 Hz, and the pole frequency fp, GFL-F = 1200 Hz. These parameters are fixed in the controllers of each converter and do not rely on online solutions.

[0055] Step 5.2 verifies that the equivalent impedance phase angle of each type of converter converges to the passive range [-90°, +90°] in their respective key high-frequency bands, and the wideband passive condition is satisfied.

[0056] Step 106: Coordinate control strategies for each frequency band and reconstruct the equivalent frequency domain impedance characteristics and oscillation modes of the global broadband admittance network of the wind farm to achieve coordinated reshaping of the broadband impedance across the entire frequency band of the wind farm.

[0057] The reconstructed equivalent frequency domain impedance characteristics and oscillation modes of the global broadband admittance network of the power station include: incorporating transient active conductance diagonal injection, control bandwidth tiered tuning, and high-frequency phase correction strategies into the elements of the global broadband admittance matrix, and reconstructing the closed-loop characteristic equation of the power station; and achieving coordinated suppression of the three frequency band oscillation modes for the low-frequency power oscillation mode, the sub-supersynchronous frequency band in-frequency resonance mode, and the high-frequency resonance instability mode, respectively.

[0058] Specifically, step 106 includes: Step 6.1: Equip each frequency band control strategy with elements of the global broadband admittance matrix, reconstruct the station closed-loop characteristic equation, and superimpose them to form the global broadband admittance matrix: The global broadband admittance matrix of the power station is composed of the passive network admittance and the equivalent admittance of each converter node: ; In the formula, This is the admittance matrix of a purely passive network without converters, including collector lines, transformers, and distributed line capacitance. Let be the node equivalent admittance matrix of the g-th unit, transformed to the global stationary coordinate system via coordinate rotation. The three-band control reshaping strategy increases the frequency of each unit in the low-frequency band. The positive-sequence admittance real part, the dispersed characteristic frequency points in the mid-frequency band, and the recovery of the passive phase in the high-frequency band drive The eigenvalues ​​are transformed from a low-damped co-frequency coupled resonance state to a high-damped broadband flat state, realizing the field-level collaborative reshaping of the characteristic mode trajectory of the global broadband admittance network.

[0059] Step 6.2: Evaluate the broadband stability of each node using the Nyquist criterion based on the eigenvalues ​​of the loop matrix. Define the loop matrix L(jω) and calculate the signed Nyquist stability margin M: Broadband stability assessment employs the Nyquist criterion based on the eigenvalues ​​of the loop matrix. For observation node b, the loop matrix is ​​defined as follows: ; In the formula, This is the Krone reduced-order equivalent impedance matrix viewed from node b towards the grid side. Let be the Kronal mass reduction equivalent admittance matrix viewed from node b towards the source side, both being 2×2 real matrices in the dq coordinate system. Given that the source and network sides are each stable, the necessary and sufficient condition for system stability is: The eigenvalue trajectory does not enclose the critical point (-1,j0) of the complex plane.

[0060] To quantitatively characterize the safety margin of each node from the stability boundary, a signed Nyquist stability margin M is defined: ; In the formula, Let be the number of loops in the Nyquist eigenvalue trajectory around the critical point (-1, j0). For loop matrix The k-th eigenvalue, k = 1, 2, and Ω is the set of full-band scanning frequencies. M>0 indicates that the system is stable and the greater the margin, the safer it is; M<0 indicates that the eigenvalue trajectory has surrounded the critical point, and the system is unstable.

[0061] Step 6.3: For the oscillation modes existing in the system, solve for the poles using the Newton-Raphson complex plane root-finding algorithm, calculate the damping ratio ζ of each mode, and achieve coordinated suppression of the three-band oscillation modes. For the oscillation modes existing in the system, the Newton-Raphson complex plane root-finding algorithm is used to accurately solve for them. extreme point Then, the damping ratio of the oscillation mode is calculated: ; In the formula, For the real part of the pole, The pole magnitude, ζ represents the oscillation angular frequency. ζ > 0 indicates positive damping (convergence) for this mode; ζ < 0 indicates negative damping (divergent instability). Engineering safety margin requirements stipulate ζ ≥ 0.05 for low-frequency bands and ζ ≥ 0.03 for high-frequency bands. The three-band coordinated reshaping strategy actively increases ζ in each band, guiding all oscillation modes towards the safety margin.

[0062] This embodiment Figure 6 The comparison of the time-domain waveforms of three-phase voltage and current at the grid connection point is shown. When a high-frequency active damper with asymmetric zero-pole phase correction and a current-feedforward low-pass filter is applied at 1 second, the voltage THD decreases from 10.44% to 1.91%. In the wide frequency domain, the true amplitude of the existing harmonics decreases from 1.5% of the fundamental amplitude to 0.1% of the fundamental amplitude. This intuitively demonstrates that the high-frequency active damper with asymmetric zero-pole phase correction and a current-feedforward low-pass filter can effectively suppress the dynamic oscillations of the power station and improve waveform quality.

[0063] Figure 6This is a schematic structural diagram of a device provided in an exemplary embodiment. Please refer to... Figure 6 At the hardware level, the device includes a processor 602, an internal bus 604, a network interface 606, memory 608, and non-volatile memory 610, and may also include other hardware required for its functions. One or more embodiments of the present invention can be implemented in software, for example, the processor 602 reads the corresponding computer program from the non-volatile memory 610 into memory 608 and then runs it. Of course, in addition to software implementation, one or more embodiments of the present invention do not exclude other implementation methods, such as logic devices or a combination of hardware and software, etc. That is to say, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0064] Please refer to Figure 7 A collaborative reshaping device for broadband impedance in wind farms can be applied to, for example... Figure 7 The device shown, in order to implement the technical solution of the present invention, includes: The construction unit 701 is used to construct a global node broadband admittance matrix model that takes into account the line distributed capacitance effect, and to extract the equivalent short-circuit ratio of each electrical node in the field through the Krohn reduction and elimination algorithm of the admittance matrix. The tuning unit 702 is used to reshape the wideband impedance characteristics of the heterogeneous power generation unit in the wind farm by using the equivalent short-circuit ratio of the node and the physical constraints of the converter equipment as a joint basis, and through differentiated tiered tuning of control parameters and phase frequency characteristic compensation. The first reshaping unit 703 is used to actively reshape the impedance characteristics of grid-type units in the low-frequency band by symmetrically injecting the frequency band adaptive transient active conductance into the main diagonal elements of the voltage control loop transfer function matrix in the dq rotating coordinate system. The second reshaping unit 704 is used to reshape the impedance characteristics of the sub-supersynchronous frequency band and the intermediate frequency band for various heterogeneous grid-type converter equipment containing heterogeneous grid-type units and static var generators by setting the phase-locked loop closed-loop bandwidth and low-pass filter cutoff frequency in a stepped distribution. The third reshaping unit 705 is used to introduce an asymmetric zero-pole phase correction stage for heterogeneous units in the high-frequency band. By controlling the independent constraints of delay and high-frequency damping, the zero-pole corner frequency is established respectively, and the impedance phase frequency characteristics in the high-frequency band are reshaped in a directional manner. The coordination unit 706 is used to coordinate the control strategies of each frequency band and reconstruct the equivalent frequency domain impedance characteristics and oscillation modes of the global broadband admittance network of the wind farm, so as to achieve the coordinated reshaping of the broadband impedance of the wind farm across the entire frequency band.

[0065] Optionally, the building unit 701 is specifically used for: By integrating the multi-source heterogeneous dynamic characteristics of converters with the line distributed capacitance effect, and introducing a frequency-varying damping coefficient to correct the high-frequency equivalent impedance, a global node broadband admittance matrix model is established. Based on the Kron algorithm for reducing the admittance matrix, the electrical coupling correlation matrix from the remote grid connection point to each electrical node in the field is extracted, and the features are quantitatively analyzed as the equivalent short-circuit ratio of the nodes.

[0066] Optionally, the tuning unit 702 is specifically used for: Combined with the hardware switching frequency limitation of heterogeneous converters, the control parameters of the frequency band are coordinated and tuned. Identify potential co-frequency resonance risk bands at the field station level within a global admittance matrix framework; Based on the spatial gradient of the equivalent short-circuit ratio of each electrical node in the field, the control response bandwidth of each grid-connected converter is allocated in stages. The lower the equivalent short-circuit ratio of the node, the lower the current inner loop and phase-locked loop closed-loop bandwidth are set.

[0067] Optionally, the first reshaping unit 703 is specifically used for: The equivalent short-circuit ratio is sensed in real time, and a frequency band adaptive following and gain dynamic optimization algorithm for the transient control branch is constructed. The bandpass filter cutoff frequency is biased in the frequency domain based on the square root ratio of the equivalent short-circuit ratio and the preset reference short-circuit ratio, so that the bandpass frequency band slides synchronously with the power grid strength. The transient active conductance gain is dynamically updated based on the inverse relationship between the equivalent short-circuit ratio and the reference short-circuit ratio. The gain is cascaded with a bandpass filter to generate a transient active conductance component, which is then symmetrically injected into the main diagonal elements of the outer loop control matrix of the grid-type unit voltage in the dq rotating coordinate system.

[0068] Optionally, the second reshaping unit 704 is specifically used for: For heterogeneous and grid-type converter equipment clusters connected in parallel to the same bus or with strong electrical coupling correlation, the cutoff frequency of the low-pass filter and the closed-loop bandwidth of the phase-locked loop of each equipment are determined according to the equivalent short-circuit ratio and electrical coupling correlation of each equipment node, with a fixed frequency difference margin, so that the equivalent wideband admittance response characteristic frequency points of the cluster in the sub-supersynchronous frequency band and the intermediate frequency band are staggered in the complex frequency domain.

[0069] Optionally, the third reshaping unit 705 is specifically used for: The phase correction stage is placed only in the active damped virtual impedance path and is not superimposed on the main circuit of the current control loop; The zero-point corner frequency is independently tuned based on the discrete control delay of each heterogeneous converter to provide phase lead compensation. The pole corner frequency is independently tuned with the high-frequency damping margin as the upper limit to suppress high-frequency gain amplification and form a broadband phase correction stage with asymmetrical distribution of zeros and poles in the frequency domain.

[0070] Optionally, the overall planning unit 706 is specifically used for: The transient active conductance diagonal injection, control bandwidth tiered tuning, and high-frequency phase correction strategies are equivalent to the elements of the global wideband admittance matrix, and the station closed-loop characteristic equation is reconstructed. The system achieves coordinated suppression of three frequency band oscillation modes: low-frequency power oscillation mode, sub-supersynchronous frequency band in-frequency resonance mode, and high-frequency resonance instability mode.

[0071] The systems, devices, modules, or units described in the above embodiments can be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer, which can take the form of a personal computer, laptop computer, cellular phone, camera phone, smartphone, personal digital assistant, media player, navigation device, email sending and receiving device, game console, tablet computer, wearable device, or any combination of these devices.

[0072] In a typical configuration, a computer includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0073] Memory may include non-persistent storage in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0074] Computer-readable media, including both permanent and non-permanent, removable and non-removable media, can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, disk storage, quantum memory, graphene-based storage media or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0075] For any other form of computer-readable medium (or computer-readable storage medium) as described above, computer instructions may be stored thereon, which, when executed by a processor, implement one or more of the above embodiments, thereby realizing the technical solution of the present invention.

[0076] The present invention also proposes a computer program that, when executed by a processor, implements one or more of the embodiments described above, thereby realizing the technical solution of the present invention. This computer program may be specifically recorded on the above-described or other computer-readable media, and the present invention does not impose any limitations on this.

[0077] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0078] The foregoing has described specific embodiments of the invention. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims may be performed in a different order than that shown in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are possible or may be advantageous.

[0079] The terminology used in one or more embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” used in one or more embodiments of the invention and in the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0080] It should be understood that although the terms first, second, third, etc., may be used to describe various information in one or more embodiments of the present invention, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first information may also be referred to as second information without departing from the scope of one or more embodiments of the present invention, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0081] The above description is merely a preferred embodiment of one or more embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of the present invention should be included within the protection scope of one or more embodiments of the present invention.

Claims

1. A method for collaborative reshaping of broadband impedance in wind farms, characterized in that, include: A global node broadband admittance matrix model considering the distributed capacitance effect of the line is constructed, and the equivalent short-circuit ratio of each electrical node in the field is extracted by the Krohn reduction and elimination algorithm of the admittance matrix. Based on the equivalent short-circuit ratio of the nodes and the physical constraints of the converter equipment, the wide-band impedance characteristics of the heterogeneous power generation units in the wind farm are reshaped through differentiated tiered tuning of control parameters and phase frequency characteristic compensation. In the low-frequency band, for grid-type units, the impedance characteristics in the low-frequency band are actively reshaped by symmetrically injecting the frequency band adaptive transient active conductance into the main diagonal elements of the voltage control loop transfer function matrix in the dq rotating coordinate system. In the sub-supersynchronous frequency band and intermediate frequency band, for various heterogeneous grid-type converter equipment containing heterogeneous grid-type units and static var generators, the impedance characteristics of the sub-supersynchronous frequency band and intermediate frequency band are reshaped by adjusting the phase-locked loop closed-loop bandwidth and low-pass filter cutoff frequency in a stepped distribution. In the high-frequency band, for heterogeneous units, an asymmetric zero-pole phase correction stage is introduced. By controlling the delay and high-frequency damping, the zero-pole corner frequency is established respectively, and the impedance phase frequency characteristics in the high-frequency band are reshaped in a directional manner. By coordinating control strategies across frequency bands and reconstructing the equivalent frequency domain impedance characteristics and oscillation modes of the global broadband admittance network of the wind farm, the synergistic reshaping of the broadband impedance across the entire frequency band of the wind farm can be achieved.

2. The method according to claim 1, characterized in that, The construction of a global node broadband admittance matrix model considering the distributed capacitance effect of the line, and the extraction of the equivalent short-circuit ratio of each electrical node in the field using the Krohn reduction and elimination algorithm of the admittance matrix, includes: By integrating the multi-source heterogeneous dynamic characteristics of converters with the line distributed capacitance effect, and introducing a frequency-varying damping coefficient to correct the high-frequency equivalent impedance, a global node broadband admittance matrix model is established. Based on the Kron algorithm for reducing the order of admittance matrix, the electrical coupling correlation matrix from the remote grid connection point to each electrical node in the field is extracted, and the main diagonal elements of the self-impedance are quantitatively analyzed as the equivalent short-circuit ratio of the node.

3. The method according to claim 1, characterized in that, The differentiated step-by-step tuning of control parameters and phase frequency characteristic compensation include: Combined with the hardware switching frequency limitation of heterogeneous converters, the control parameters of the frequency band are coordinated and tuned. Identify potential co-frequency resonance risk bands at the field station level within the framework of the global admittance matrix; Based on the spatial gradient of the equivalent short-circuit ratio of each electrical node in the field, the control response bandwidth of each grid-connected converter is allocated in stages. The lower the equivalent short-circuit ratio of the node, the lower the current inner loop and phase-locked loop closed-loop bandwidth are set.

4. The method according to claim 1, characterized in that, For grid-connected units, the low-frequency impedance characteristics are actively reshaped by symmetrically injecting frequency-adaptive transient active conductance into the main diagonal elements of the voltage control loop transfer function matrix in a dq rotating coordinate system, including: Real-time sensing of the equivalent short-circuit ratio of the nodes; constructing a frequency band adaptive following and gain dynamic optimization algorithm for transient control branches. The bandpass filter cutoff frequency is biased in the frequency domain based on the ratio of the square root of the equivalent short-circuit ratio of the node to the preset reference short-circuit ratio, so that the bandpass frequency band slides synchronously with the power grid strength. The transient active conductance gain is dynamically updated based on the inverse relationship between the node equivalent short-circuit ratio and the reference short-circuit ratio. The gain is cascaded with a bandpass filter to generate a transient active conductance component, which is then symmetrically injected into the main diagonal elements of the outer loop control matrix of the grid-type unit voltage in the dq rotating coordinate system.

5. The method according to claim 1, characterized in that, The aforementioned heterogeneous grid-type converter equipment, including heterogeneous grid-type units and static var generators, utilizes a tiered distribution of phase-locked loop closed-loop bandwidth and low-pass filter cutoff frequency to reshape the impedance characteristics of the sub-supersynchronous frequency band and intermediate frequency band, including: For heterogeneous and grid-type converter equipment clusters connected in parallel to the same bus or with strong electrical coupling correlation, the cutoff frequency of the low-pass filter and the closed-loop bandwidth of the phase-locked loop of each equipment are determined according to the equivalent short-circuit ratio and electrical coupling correlation of each equipment node, with a fixed frequency difference margin, so that the equivalent wideband admittance response characteristic frequency points of the cluster in the sub-supersynchronous frequency band and the intermediate frequency band are staggered in the complex frequency domain.

6. The method according to claim 1, characterized in that, For heterogeneous generator sets, an asymmetric zero-pole phase correction stage is introduced. By controlling the independent constraints of delay and high-frequency damping, the zero-pole corner frequencies are established, thus directionally reshaping the high-frequency impedance phase-frequency characteristics. This includes: The phase correction stage is placed only in the active damped virtual impedance path and is not superimposed on the main circuit of the current control loop; The zero-point corner frequency is independently tuned based on the discrete control delay of each heterogeneous converter to provide phase lead compensation. The pole corner frequency is independently tuned with the high-frequency damping margin as the upper limit to suppress high-frequency gain amplification and form a broadband phase correction stage with asymmetrical distribution of zeros and poles in the frequency domain.

7. The method according to claim 1, characterized in that, The equivalent frequency domain impedance characteristics and oscillation modes of the reconstructed global broadband admittance network of the power station include: The transient active conductance diagonal injection, control bandwidth tiered tuning, and high-frequency phase correction strategies are equivalent to the elements of the global wideband admittance matrix, and the station closed-loop characteristic equation is reconstructed. The system achieves coordinated suppression of three frequency band oscillation modes: low-frequency power oscillation mode, sub-supersynchronous frequency band in-frequency resonance mode, and high-frequency resonance instability mode.

8. A device for co-reshaping broadband impedance in wind farms, characterized in that, include: Construction Unit: Construct a global node broadband admittance matrix model that takes into account the distributed capacitance effect of the line, and extract the equivalent short-circuit ratio of each electrical node in the field through the Krohn reduction and elimination algorithm of the admittance matrix; Tuning Unit: Based on the equivalent short-circuit ratio of the nodes and the physical constraints of the converter equipment, the wide-band impedance characteristics of the heterogeneous power generation units in the wind farm are reshaped through differentiated tiered tuning of control parameters and phase frequency characteristic compensation. First reshaping unit: In the low-frequency band, for grid-type units, the impedance characteristics in the low-frequency band are actively reshaped by symmetrically injecting the frequency band adaptive transient active conductance into the main diagonal elements of the voltage control loop transfer function matrix in the dq rotating coordinate system. The second reshaping unit: In the sub-supersynchronous frequency band and intermediate frequency band, for each heterogeneous and heterogeneous grid-type converter equipment containing heterogeneous grid-type units and static var generators, the impedance characteristics of the sub-supersynchronous frequency band and intermediate frequency band are reshaped by adjusting the phase-locked loop closed-loop bandwidth and low-pass filter cutoff frequency in a stepped distribution. The third reshaping unit: In the high-frequency band, for heterogeneous units, an asymmetric zero-pole phase correction stage is introduced. By controlling the delay and high-frequency damping, the zero-pole corner frequency is established respectively, and the impedance phase frequency characteristics in the high-frequency band are reshaped in a directional manner. Coordination Unit: Coordinates control strategies across frequency bands and reconstructs the equivalent frequency domain impedance characteristics and oscillation modes of the global broadband admittance network of the wind farm to achieve coordinated reshaping of the broadband impedance across the entire frequency band of the wind farm.

9. An electronic device, characterized in that, include: processor; Memory used to store processor-executable instructions; The processor implements the steps of the method as described in any one of claims 1-7 by running the executable instructions.

10. A computer-readable storage medium storing computer instructions thereon, characterized in that, When executed by the processor, this instruction implements the steps of the method as described in any one of claims 1-7.

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