A simplified equivalent method for direct-drive wind turbines based on controlled sources

Abstract

The present invention relates to a simplified equivalent method for a direct-drive wind turbine generator set based on a controlled source, comprising: obtaining d-axis and q-axis current components according to a three-phase current at a machine end, obtaining d-axis and q-axis voltage components at a machine end based on active and reactive power at the machine end, calculating a machine end voltage amplitude, and obtaining a machine end voltage phase through vector control; using the machine end voltage amplitude and the machine end voltage phase as control signals for a machine end controlled voltage source to complete modeling; obtaining d-axis and q-axis current components according to a three-phase current at a grid side, calculating grid side d-axis and q-axis current reference values ​​according to whether a fault is currently occurring, and obtaining a grid side voltage amplitude; using the grid side voltage phase and the grid side voltage amplitude as control signals for a grid side controlled voltage source to complete modeling; and calculating a DC bus current as a control signal for a controlled current source based on tracked machine end active power, grid side active power, and DC bus voltage to complete modeling.

Description

Technical Field

[0001] The present invention relates to the technical field of wind power generation system modeling and simulation, and in particular to a simplified equivalent method for a direct-drive wind turbine generator set based on a controlled source. Background Art

[0002] As global wind power installed capacity continues to climb, offshore wind farms have entered the gigawatt era, with single-unit capacity exceeding 15MW. This has created an unprecedented and urgent need for high-precision, real-time simulation technology. However, electromagnetic transient simulation of permanent magnet direct-drive turbines has long faced a core dilemma: achieving both accuracy and efficiency. While traditional idealized average models significantly increase simulation speeds by simplifying the converter into an ideal controlled source, their fixed-parameter voltage source control scheme leads to significant distortion of key dynamic characteristics.

[0003] Chinese patent application publication number CN111293713A discloses a method for establishing a simulation model and simulation method for a wind farm wind turbine converter. By equating the wind farm's generator-side and grid-side converters to AC controlled voltage sources and using DC energy storage capacitors to establish a power transmission model, this method addresses the computationally intensive problem of wind farm wind turbine converter simulation analysis and enables efficient wind farm system simulation. However, this model fails to consider the dynamic coordinated regulation relationship between voltage amplitude (gmag) and phase angle (theta), making it unable to accurately represent the real-time behavior of the converter's actual control logic.

[0004] When a ground fault occurs, traditional simplified models completely lose their transient simulation capabilities. During voltage dips, the phase-locked loop (PLL) tracking error is significant, causing reactive current phase misalignment. In asymmetric fault scenarios, due to the lack of a zero-sequence current compensation channel, the simulated ground current value deviates significantly from the actual operating conditions, directly leading to failure in verifying the protection device's operating logic. Furthermore, in complex faults like symmetrical short circuits, the converter's reactive power support capability deviates significantly from actual operating conditions due to the lack of consideration of voltage amplitude-phase feedforward compensation, threatening the unit's safety assessment and reliability. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a simplified equivalent method for direct-drive wind turbines based on controlled sources, so as to solve or partially solve the problems of lag in voltage amplitude response and large tracking error in the model.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] One aspect of the present invention provides a simplified equivalent method for a direct-drive wind turbine generator system based on a controlled source, comprising:

[0008] The modeling process of the machine-side converter:

[0009] The d-axis and q-axis current components are obtained based on the three-phase current at the machine end. The d-axis and q-axis voltage components at the machine end are obtained based on the active and reactive power at the machine end. The machine end voltage amplitude is calculated and the machine end voltage phase is obtained through vector control.

[0010] The machine-side voltage amplitude and phase are used as the control signals of the machine-side controlled voltage source to complete the modeling;

[0011] Grid-side converter modeling process:

[0012] The d-axis and q-axis current components are obtained based on the three-phase current on the grid side. Based on whether there is a fault, the d-axis and q-axis current reference values ​​on the grid side are calculated to obtain the grid side voltage amplitude.

[0013] The grid-side voltage phase and grid-side voltage amplitude are used as control signals of the grid-side controlled voltage source to complete the modeling;

[0014] Modeling process of DC crowbar:

[0015] Based on the tracked active power at the machine end, the active power at the grid side, and the DC bus voltage, the DC bus current is calculated as the control signal of the controlled current source to complete the modeling.

[0016] As a preferred technical solution, during the machine-side converter modeling process and the grid-side converter modeling process, the machine-side / grid-side voltage amplitude is updated through the gmag-theta dynamic control mechanism, and the voltage amplitude and phase fluctuation are fed back to the modulation link in real time through the state-space equation, thereby reducing the response lag of the traditional model, and dynamically decoupling each sequence component through the phase-locked loop to reduce the machine-side / grid-side phase tracking error.

[0017] As an optimal technical solution, for the modeling process of the DC crowbar, in response to detecting a fault on the grid side, the fault isolation is achieved by cutting off the electrical connection between the generator side and the grid side, and the local control strategy of the unit based on the state-space equation actively adjusts the converter modulation signal to limit the power fluctuation on the generator side to a safety margin.

[0018] As an optimal technical solution, for the modeling process of the DC crowbar, by reconstructing the dynamic coupling relationship between the crowbar control signal and the modulation wave of the machine-side converter, the grid-side fault point is electrically isolated from the machine-side generator at the moment of the fault, thereby avoiding the DC voltage out of control or the generator being disconnected from the grid due to the fixed unloading resistance value.

[0019] As a preferred technical solution, according to whether there is a current fault, the grid-side d-axis and q-axis current reference values ​​are calculated using the following formula:

[0020]

[0021]

[0022] If the current fault is not occurring:

[0023]

[0024]

[0025] If the current fault:

[0026]

[0027]

[0028]

[0029] in, 、 They are Initial current reference values ​​of d-axis and q-axis at time, is the DC voltage error, is the integration time constant, is the grid-side reactive power, 、 are the calculated grid-side d-axis and q-axis current reference values, is the effective value of the grid-side voltage, is the upper limit of the grid-side d-axis current, is the rated current.

[0030] As a preferred technical solution, the grid-side voltage amplitude is calculated using the following formula:

[0031]

[0032]

[0033]

[0034] in, 、 They are The voltage components of the d-axis and q-axis on the grid side at the moment, 、 are the calculated grid-side d-axis and q-axis current reference values, 、 are the grid-side d-axis and q-axis current components respectively, is the grid-side voltage amplitude, is the DC bus voltage.

[0035] As a preferred technical solution, the DC bus current is calculated using the following formula:

[0036]

[0037] in, is the DC bus current, is the active power at the machine end, is the grid-side active power, is the DC bus voltage.

[0038] As a preferred technical solution, in the grid-side converter modeling process, the grid-side voltage phase is obtained by performing Park inverse transformation on the grid-side d-axis voltage component and the grid-side q-axis voltage component and then connecting them to a phase-locked loop.

[0039] Another aspect of the present invention provides an electronic device comprising: one or more processors and a memory, wherein the memory stores one or more programs, and the one or more programs include instructions for executing the aforementioned simplified equivalent method of a direct-drive wind turbine generator system based on a controlled source.

[0040] Another aspect of the present invention provides a computer-readable storage medium comprising one or more programs for execution by one or more processors of an electronic device, wherein the one or more programs include instructions for executing the aforementioned simplified equivalent method for a direct-drive wind turbine generator system based on a controlled source.

[0041] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0042] (1) Rapid feedback of power fluctuations and small tracking error: The present invention provides a design of gmag-theta dynamic control, which dynamically generates voltage amplitude (gmag) based on electromagnetic torque-speed closed-loop control, and feeds back power fluctuations to the modulation link in real time through the transfer function to eliminate response lag. In addition, the generalized integral phase-locked loop is used to dynamically decouple each sequence component, so that the phase angle (theta) tracking error is compressed from ±5° of the traditional model to within ±0.5°, which greatly improves the operating efficiency while ensuring the accuracy of the simulation.

[0043] (2) Modeling for rapid decoupling and precise control of generator-side and grid-side energy in grid-side fault scenarios: The present invention uses a crowbar circuit equivalent model to operate in the event of a grid fault, quickly disconnecting the electrical connection between the generator and grid sides to achieve fault isolation. The unit local control strategy based on the state-space equation actively adjusts the generator excitation current and the converter modulation signal, limiting power fluctuations within a safety margin, thereby maintaining continuous operation of the unit. At the same time, by reconstructing the dynamic coupling relationship between the crowbar control signal and the generator-side converter modulation wave, the grid-side fault point is electrically isolated from the generator-side generator at the moment of the fault, avoiding the DC voltage out-of-control or generator disconnection problems caused by the fixed unloading resistance value in the traditional model. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1Flowchart of a simplified equivalent method for a direct-drive wind turbine generator system based on a controlled source in an embodiment;

[0045] Figure 2 This is the DC bus voltage waveform of the detailed model;

[0046] Figure 3 To simplify the model DC bus voltage waveform;

[0047] Figure 4 This is the three-phase current waveform of the grid side of the detailed model;

[0048] Figure 5 To simplify the model grid-side three-phase current waveform;

[0049] Figure 6 This is the waveform of the grid voltage RMS when a three-phase short circuit fault occurs in the detailed model at the 3rd second;

[0050] Figure 7 To simplify the model, the grid voltage RMS waveform is shown when a three-phase short circuit fault occurs in the 3rd second.

[0051] Figure 8 This is the grid voltage reference effective value waveform diagram when a three-phase short circuit fault occurs in the 3rd second;

[0052] Figure 9 This is the DC bus voltage waveform when a three-phase short circuit fault occurs in the detailed model at the 3rd second;

[0053] Figure 10 To simplify the model, the DC bus voltage waveform is shown when a three-phase short circuit fault occurs in the power grid at the 3rd second;

[0054] Figure 11 This is the switching logic waveform of the DC crowbar when a three-phase short circuit fault occurs in the power grid at the 3rd second of the detailed model;

[0055] Figure 12 To simplify the model, the switching logic waveform of the DC crowbar is shown when a three-phase short circuit fault occurs in the power grid at the 3rd second;

[0056] Figure 13 It is the reactive support waveform during the detailed model fault period;

[0057] Figure 14 To simplify the reactive support waveform during the model fault period;

[0058] Figure 15 This is the waveform of the grid-connected active power of the unit during the detailed model fault period;

[0059] Figure 16 To simplify the model, the grid-connected active power waveform of the unit during fault period;

[0060] Figure 17To simplify the active output waveform during the model fault period;

[0061] Figure 18 To simplify the model, the active reference value output waveform during fault period;

[0062] Figure 19 A schematic diagram of an electronic device. DETAILED DESCRIPTION

[0063] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0064] Example 1

[0065] In response to the problems of low computational efficiency and high-frequency noise interference control strategy verification caused by detailed switch modeling of the converter in the aforementioned existing technology, the present embodiment provides a simplified equivalent method for direct-drive wind turbines based on controlled sources. The method reconstructs the key characteristics of the converter through dynamic control signals (gmag / theta), significantly improving the simulation speed while ensuring accuracy.

[0066] For example, see Figure 1 ,This method mainly includes the modeling process of the grid-side converter, the generator-side converter and the DC crowbar, including:

[0067] Step S1: Modeling the machine-side converter. Specifically, step S1 may include steps S101-S104:

[0068] Step S101 : Tracking the active power and reactive power at the machine end to obtain the d-axis and q-axis current components at the machine end.

[0069] Real-time tracking of machine-side active power Reactive power at the machine end At the same time, the three-phase current at the machine end is transformed by Parker to obtain the d-axis current component and the q-axis current component .

[0070] Step S102: obtaining the d-axis and q-axis voltage components at the machine end after decoupling control.

[0071] The reactive power at the machine end is obtained and the d-axis current component The d-axis voltage component at the machine end is obtained through decoupling control .

[0072] The active power at the machine end is obtained and the q-axis current component , after decoupling control, the q-axis voltage component at the machine end is obtained .

[0073] Step S103: the phase angle of the voltage at the computer end and the amplitude of the voltage at the machine end.

[0074] (1)

[0075] and The voltage phase angle at the machine end can be obtained through vector control .

[0076] in, is the DC bus voltage, is the d-axis voltage component at the machine end, is the q-axis voltage component at the machine end, is the voltage amplitude at the generator terminal.

[0077] Step S104: input the generator-end voltage phase angle and the generator-end voltage amplitude as control signals into the generator-end controlled voltage source.

[0078] The generator terminal voltage amplitude will be Phase angle with terminal voltage As the control signal input terminal controlled voltage source, the phase angle signal Directly control the output phase shift of the voltage source, the amplitude signal The voltage amplitude is dynamically adjusted, and the two together drive the same voltage source to achieve controlled output. The controlled quantity of the machine-side controlled voltage source is the voltage amplitude and phase angle, and its output voltage is an AC sinusoidal voltage. The specific expression is:

[0079] .

[0080] Step S2: Grid-side converter modeling. Specifically, step S2 may include steps S201-S205:

[0081] Step S201 : Track the grid-side active power and the generator-side reactive power to obtain the grid-side d-axis and q-axis current components.

[0082] Real-time tracking of grid-side active power and reactive power At the same time, the three-phase current on the grid side is transformed by Parker to obtain the grid side d-axis current component and the grid-side q-axis current component , the grid side voltage reference phase is obtained through the phase-locked loop , which will be used as the angle variable of the input rotation coordinate system in the subsequent step S204 Parker inverse transformation to define the real-time position of the DQ axis relative to the ABC coordinate system.

[0083] Step S202 , calculating grid-side d-axis and q-axis initial current reference values.

[0084] (2)

[0085] The grid-side d-axis initial current reference value is calculated by formula (2): ,in is the DC voltage error, The integral time constant is 0.014.

[0086] (3)

[0087] The grid-side q-axis initial current reference value is calculated by formula (3): ,in is the grid-side reactive power, The integral time constant is 0.014.

[0088] Step S203 , calculating fault / non-fault grid-side d-axis and q-axis current reference values.

[0089] In non-fault conditions, the grid-side q-axis current reference value is and Equal, grid side d-axis current reference value and equal.

[0090] When a fault occurs,

[0091] (4)

[0092] (5)

[0093] (6)

[0094] in is the rated current, is the effective value of the grid-side voltage, It is the upper limit of the grid-side d-axis current.

[0095] Specifically, the fault may be a single-phase short circuit, a two-phase short circuit, a two-phase ground short circuit, or a three-phase short circuit.

[0096] Step S204 , calculating the grid-side d-axis and q-axis voltage components to obtain the grid-side voltage amplitude and grid-side voltage phase.

[0097] (7)

[0098] (8)

[0099] The grid-side d-axis voltage component is calculated by formula (7) and formula (8): and the grid-side q-axis voltage component ,in is the grid-side d-axis current component, Grid-side q-axis current component.

[0100] (9)

[0101] The grid-side voltage amplitude is calculated by formula (9): , and the grid-side d-axis voltage component and the grid-side q-axis voltage component After performing the inverse Park transform and connecting to the phase-locked loop, the grid-side voltage phase is obtained. .

[0102] Step S205 : inputting the grid-side voltage amplitude and the grid-side voltage phase as control signals into the grid-side controlled voltage source.

[0103] The grid side voltage amplitude will be obtained Phase with grid-side voltage As the control signal input to the grid-side controlled voltage source: .

[0104] Step S3: DC crowbar modeling. This model consists of a controlled current source connected in parallel with the DC crowbar. Specifically, step S3 may include steps S301-S303:

[0105] Step S301 , tracking the active power at the generator end, the active power at the grid side, and the DC bus voltage.

[0106] Real-time tracking of machine-side active power , grid-side active power and DC bus voltage .

[0107] Step S302: Calculate and obtain the DC bus current.

[0108] (10)

[0109] The DC bus current can be calculated ,in is the active power at the machine end, is the grid-side active power, is the DC bus voltage.

[0110] Step S303: input the obtained DC bus current as a control signal to the controlled current source.

[0111] The obtained DC bus current is input into the controlled current source as a control signal.

[0112] The control logic of the DC crowbar is:

[0113] (1) Calculation of DC voltage error in the control logic of the DC crowbar.

[0114] The input signal is a DC voltage error , defined as the difference between the reference voltage and the actual voltage:

[0115]

[0116] Where, Set to 1.1, is the DC voltage of the machine-end converter.

[0117] (2) Proportional-integral (PI) control link.

[0118] The error signal is amplified by a factor of 10 through the proportional term:

[0119]

[0120] The integral term will be realized through the integrator 1 / sT (i.e., the transfer function form). The transfer function refers to solving the q-axis voltage through the active power and q-axis current on the generator side, and solving the d-axis voltage through the reactive power and d-axis current.

[0121]

[0122] From the above, the total control signal can be obtained:

[0123]

[0124] (3) Logic chopping module.

[0125] The chopping logic is triggered by the comparator and the threshold is set to (Triangle wave with a frequency of 1000 Hz and a duty cycle of 50%)

[0126]

[0127] When Chop(t)=1, the crowbar circuit is activated to cut off the connection between the machine side and the grid side; otherwise, it is shut down.

[0128] To verify the effectiveness of this method, the constructed equivalent model was verified and switched. Specifically, the DC bus voltage and grid-connected three-phase current waveforms were recorded during normal simulation. A three-phase short circuit fault was constructed on the 10kV AC bus. The 'timefault logic' was set so that a three-phase short circuit occurred at the 5th second of the simulation run. The short circuit lasted for 0.625 seconds. The AC bus three-phase voltage, DC bus voltage, and three-phase grid-connected current were recorded. The simulation results are shown in Figure 2. Figure 2-Figure 16 shown.

[0129] like Figures 2 to 5 As shown in the figure, the DC bus voltage and grid-side three-phase current in the detailed model and the simplified model are highly consistent with each other, and the steady-state error is small, which verifies the ability of the dynamic equivalent mechanism to restore the essential nonlinear characteristics of the converter. Figure 2 (Detailed model) shows the high-frequency small fluctuations of the DC bus voltage, Figure 3 The DC bus voltage in the simplified model (curve A in the figure) almost coincides with the reference value (line B at 1.100 kV), fluctuating smoothly only within 1.10 kV ± 0.005 kV. This indicates that the model ignores high-frequency details through equivalent averaging, significantly improving simulation speed and enabling rapid verification of system-level stability. Figure 4 (Detailed model) The three-phase current on the grid side presents a regular sinusoidal waveform over a period of time, with a strict phase difference of 120° and extremely low harmonic content; Figure 5 (Simplified model) Equivalent amplitude to kiloamperes, ignoring high-frequency details through equivalent averaging, making the current curve smoother. Although microscopic details are lost, the three-phase balance and macroscopic characteristics of energy interaction are retained, which can achieve multi-unit grid-level simulation efficiency optimization. Figure 4 and Figure 5 A, B, and C represent the waveforms of the three phases respectively. Figure 7 (Simplified model) During a 3-second fault, the voltage drops to 0.12 kV with two fluctuations, and the complete restoration Figure 6 (Detailed model) The nonlinear characteristics of the electromagnetic transient process show a gentle "sudden drop-maintain-linear recovery" trend, reflecting that the model can improve computational efficiency and is suitable for quickly evaluating steady-state recovery capabilities. Figure 6 、 Figure 7 The curve and Figure 8 The overlap between the two curves (reference curve) is high, which verifies that the simplified model accurately equates the electromagnetic transient characteristics through the gmag-theta dynamic control mechanism.

[0130] Figure 9 (Detailed model) During a 3-second fault, the DC voltage climbed from 1.10 kV to 1.18 kV with high-frequency oscillations. Figure 10(Simplified model) The voltage drop is deeper and the fluctuations are more severe during the recovery phase. It fully presents the dynamic response of the switching device and the electromagnetic transient details, and can be used to evaluate the global robustness of the control strategy.

[0131] Figure 11 (Detailed Model) During a fault, the crowbar switch logic (chop) presents a high-frequency pulse with an amplitude of 0-1, accurately replicating the discrete action characteristics of the switching device; Figure 12 (Simplified model) also presents high-frequency pulses with an amplitude of 0-1, perfectly replicating the crowbar switching logic of the detailed model and retaining the macro-logical characteristics of the crowbar's rapid switching during a fault.

[0132] During a severe three-phase short-circuit fault in the power grid, the grid-side converter strictly follows the "reactive power priority" control strategy. Figure 13 (Detailed model) Outputs 0.15 per-unit capacitive reactive power within 3 milliseconds after a 3.0-second fault is triggered and remains stable, effectively supporting grid voltage recovery. Figure 14 The response curve of the simplified model has a high degree of coincidence with the detailed model, with a transient error of less than 0.02 per unit, accurately restoring the reactive power control logic. To maximize reactive power output capacity, both models actively unload active power to near zero. Figure 15 (Detailed Model) down to 0.02 per unit, Figure 16 (Simplified model) down to 0.03 per unit. The extremely low deviation of 0.01 per unit between the two fully verifies the equivalence of the gmag-theta dynamic control mechanism to the power decoupling strategy under fault conditions. After the fault is cleared, based on the precise control of the DC crowbar dynamic coupling model, active power is restored at a fixed slope of 0.5 per unit per second, and reactive power support is smoothly exited within 20 milliseconds, ultimately achieving power coordination and stability. The dynamic response throughout the process maintains millisecond-level synchronization, and the steady-state error remains below 0.005 per unit.

[0133] Figure 17 (Simplified model actual active power) shows that during the period of 3 to 3.8 seconds, the actual power shows a step-by-step fluctuation downward trend, which is consistent with Figure 18 (Simplified model reference curve) The maximum instantaneous deviation reaches 0.02 per unit, indicating that the system has a dynamic response delay of about 10 milliseconds during the power command adjustment process, but the overall system can still effectively track the power command changes.

[0134] In the simulation test, a three-phase short-circuit fault condition was triggered in the third second of the test, simulating an extreme operating state in which the grid voltage suddenly dropped to 20% of the rated value (lasting 625ms, in compliance with the requirements of the low voltage ride-through standard GB / T 36995-2018).

[0135] Waveform data shows that when the system detected an abnormal voltage drop, the unit maintained grid-connected operation through a dynamic coordinated control strategy. The DC-side crowbar protection device activated the load shedding circuit within 12ms of the fault, successfully stabilizing the bus voltage below the 1.2kV safety threshold. During the fault, the grid-side converter prioritized reactive power support, rapidly outputting capacitive reactive power to support grid voltage recovery. In the severe fault described above, active power dropped to essentially zero during the fault to ensure reactive power output capacity. After the fault cleared, active power recovered at the programmed slope, ultimately stabilizing both active and reactive power.

[0136] It is particularly worth noting that the simplified model provided in this embodiment not only completely reproduces the dynamic transition process of the fault current, but also its key parameters (including voltage recovery curve, unloading power fluctuation, etc.) are all controlled within 5% when compared with the actual measured data of the physical prototype, verifying the equivalent modeling method's ability to accurately characterize complex fault scenarios.

[0137] This embodiment deeply integrates the grid support strategy during low voltage ride-through, synchronously injecting dynamic reactive current during the crowbar action, and ensuring that the voltage support strength of the grid connection point complies with the GB / T 36995-2018 standard through closed-loop regulation of voltage amplitude and phase. Traditional equivalent models do not establish a machine-grid decoupling control channel and cannot simulate the coordinated process of continuous generator operation and grid support during faults. Simulation results show that in the three-phase short-circuit fault scenario, the DC bus voltage fluctuation amplitude of this solution deviates from the measured data by less than 2%, the crowbar circuit response time is shortened from 10ms in the traditional model to 3ms, and the generator maintains more than 95% of the rated power output during the fault, providing a high-confidence simulation foundation for wind turbine fault ride-through control and grid adaptability.

[0138] Example 2

[0139] Based on Example 1, this embodiment provides an electronic device, including: one or more processors and a memory, wherein the memory stores one or more programs, and the one or more programs include instructions for executing the BMS control method as described in Example 1.

[0140] like Figure 17 As mentioned above, at the hardware level, the electronic device includes a processor, an internal bus, a network interface, a memory and a non-volatile memory, and may also include other hardware required for the business. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to achieve the above Figure 17 Of course, in addition to software implementation, the present invention does not exclude other implementation methods, such as logic devices or a combination of software and hardware, etc., that is, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0141] Memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. Memory is an example of a computer-readable medium.

[0142] Example 3

[0143] Based on the aforementioned embodiment, this embodiment provides a computer-readable storage medium, including one or more programs for execution by one or more processors of an electronic device, wherein the one or more programs include instructions for executing the aforementioned method.

[0144] Computer-readable media includes permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. The information can be computer-readable instructions, data structures, program modules, 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 technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices, or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media does not include transitory media such as modulated data signals and carrier waves.

[0145] In summary, the present invention reconstructs the dynamic response characteristics of the converter by using the equivalent of a dynamically controlled voltage source and taking the voltage amplitude and phase angle as the core control signals: by introducing the dynamic compensation algorithm for the grid-side d-axis current upper limit and the voltage amplitude-phase coordinated adjustment mechanism, this simplified model can still fully simulate the fault current transition process when three-phase grounding, high-resistance grounding and other faults occur, accurately capture the transient voltage fluctuation characteristics caused by the sudden change of grounding resistance, and reduce the simulation error by more than 80% compared with the traditional model. By dynamically adjusting the voltage amplitude generated by the machine-side electromagnetic torque and the DC bus voltage and the phase angle obtained by the phase-locked loop dynamically tracking the grid phase in real time, the closed-loop modulation behavior of the converter is accurately simulated; a DC bus dynamic model based on the state-space equation is designed to replace the traditional fixed parameter method to achieve precise control of the reactive current phase and delay error during low voltage crossing. This method achieves a significant improvement in simulation efficiency in PSCAD and is fully compatible with hardware-in-the-loop testing, supporting real-time simulation requirements at the wind farm level.

[0146] By combining the gmag-theta dynamic control mechanism with traditional models, the present invention overcomes bottlenecks such as ground fault simulation distortion and harmonic suppression failure without sacrificing simulation speed. This provides high-precision and real-time simulation technology support for wind farm cluster control strategy optimization and flexible direct current grid-connected dynamic stability analysis, promoting the transformation of traditional models from static simplification to dynamic.

[0147] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions are intended to be within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope of protection of the claims.

Claims

1. A simplified equivalent method for direct-drive wind turbines based on controlled sources, characterized in that: include: The modeling process of the machine-side converter: The d-axis and q-axis current components are obtained based on the three-phase current at the machine end. The d-axis and q-axis voltage components at the machine end are obtained based on the active and reactive power at the machine end. The machine end voltage amplitude is calculated and the machine end voltage phase is obtained through vector control. The machine-side voltage amplitude and phase are used as the control signals of the machine-side controlled voltage source to complete the modeling; Grid-side converter modeling process: The d-axis and q-axis current components are obtained based on the three-phase current on the grid side. Based on whether there is a fault, the d-axis and q-axis current reference values ​​on the grid side are calculated to obtain the grid side voltage amplitude. The grid-side voltage phase and grid-side voltage amplitude are used as control signals of the grid-side controlled voltage source to complete the modeling; The modeling process of the DC crowbar: Based on the tracked active power at the machine end, the active power at the grid side, and the DC bus voltage, the DC bus current is calculated as the control signal of the controlled current source to complete the modeling. According to whether there is a fault, the grid-side d-axis and q-axis current reference values ​​are calculated using the following formula: If the current fault is not occurring: If the current fault: in, 、 They are Initial current reference values ​​of d-axis and q-axis at time, is the DC voltage error, is the integration time constant, is the grid-side reactive power, 、 are the calculated grid-side d-axis and q-axis current reference values, is the effective value of the grid-side voltage, is the upper limit of the grid-side d-axis current, is the rated current, The grid-side voltage amplitude is calculated using the following formula: in, 、 They are The voltage components of the d-axis and q-axis on the grid side at the moment, 、 are the calculated grid-side d-axis and q-axis current reference values, 、 are the grid-side d-axis and q-axis current components respectively, is the grid-side voltage amplitude, is the DC bus voltage, The DC bus current is calculated using the following formula: in, is the DC bus current, is the active power at the machine end, is the grid-side active power, is the DC bus voltage.

2. A simplified equivalent method for a direct-drive wind turbine generator system based on a controlled source according to claim 1, characterized in that: In the machine-side converter modeling process and the grid-side converter modeling process, the machine-side / grid-side voltage amplitude is updated through the voltage amplitude-phase angle dynamic control mechanism, and the voltage amplitude and phase fluctuations are fed back to the modulation link in real time through the state space equation, thereby reducing the response lag of the traditional model. The phase-locked loop dynamically decouples each sequence component to reduce the machine-side / grid-side phase tracking error.

3. The simplified equivalent method of a controlled source direct-drive wind turbine generator system according to claim 1, characterized in that: Regarding the modeling process of the DC crowbar, in response to detecting a fault on the grid side, the fault is isolated by cutting off the electrical connection between the generator side and the grid side. The local control strategy of the unit based on the state-space equation actively adjusts the converter modulation signal to limit the power fluctuation on the generator side to a safety margin.

4. The simplified equivalent method of a controlled source direct-drive wind turbine generator system according to claim 1, characterized in that: Regarding the modeling process of the DC crowbar, by reconstructing the dynamic coupling relationship between the crowbar control signal and the modulation wave of the generator-side converter, the grid-side fault point is electrically isolated from the generator-side generator at the moment of fault, avoiding DC voltage loss of control or generator disconnection due to a fixed unloading resistance value.

5. The simplified equivalent method of a controlled source direct-drive wind turbine generator system according to claim 1, characterized in that: In the grid-side converter modeling process, the grid-side voltage phase is obtained by performing inverse Park transformation on the grid-side d-axis voltage component and the grid-side q-axis voltage component and then connecting them to a phase-locked loop.

6. An electronic device, characterized in that: include: One or more processors and a memory, wherein the memory stores one or more programs, and the one or more programs include instructions for executing the simplified equivalent method of a direct-drive wind turbine generator system based on a controlled source as described in any one of claims 1-5.

7. A computer-readable storage medium, characterized in that It includes one or more programs for execution by one or more processors of an electronic device, and the one or more programs include instructions for executing the simplified equivalent method of a direct-drive wind turbine generator system based on a controlled source as described in any one of claims 1-5.

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