High voltage ride through equivalent modeling method of direct-driven wind turbine generator and related device

Abstract

The embodiment of the invention discloses a high-voltage ride-through equivalent modeling method of a direct-driven wind turbine generator and a related device. The method comprises the following steps: establishing a time-varying voltage model of a common coupling point of a new energy base under a three-phase symmetric fault of a receiving-end power grid; based on the topological structure decoupling analysis of the direct-driven wind turbine generator, the correlation among the switching threshold value of the Chopper circuit, the energy consumption power and the control parameters of the grid-side converter is analyzed, and a segmented mapping equation of the output power and the alternating-current voltage under the symmetric voltage rising scene is constructed; introducing a transient energy conservation equation, and establishing a general power curve which covers the complete period of the fault and is used for representing a dynamic relationship among a Chopper action threshold value, a power amplitude limiting value and a voltage recovery rate; and integrating the voltage outer loop control characteristics of the grid-side converter and the Chopper energy consumption dynamic state to obtain a time domain analytical expression of the terminal voltage in the high voltage ride through process. The method provided by the invention overcomes the problem that the traditional modeling method is insufficient in dynamic characteristic analysis of the whole process of the fault.

Description

Technical Field

[0001] The present invention relates to the field of renewable energy power generation technology, and in particular to a high voltage ride-through equivalent modeling method and related devices for a direct-drive wind turbine generator system. Background Art

[0002] Against the backdrop of a dual-carbon economy, the proportion of renewable energy in the power grid continues to rise. By 2024, China's cumulative installed capacity of renewable energy power generation will be approximately 3.35 billion kilowatts, a year-on-year increase of 14.6%. This includes approximately 890 million kilowatts of solar power generation, a year-on-year increase of 45.2%, and approximately 520 million kilowatts of wind power generation, a year-on-year increase of 18.0%. This reflects the significant progress my country has made in promoting energy transformation and building a clean, low-carbon power system.

[0003] As the proportion of renewable energy in the power grid continues to rise, the traditional power generation method, primarily based on synchronous generators, is gradually being replaced by low-inertia generation methods such as wind and solar power, leading to a gradual transition to a low-inertia power system. Traditional synchronous generators, through their mechanical inertia, can effectively mitigate grid frequency fluctuations and ensure system stability. However, renewable energy sources such as wind and photovoltaic power lack this inertial response capability, making it difficult for the grid to recover from frequency fluctuations in the event of a fault. Typical examples include the August 9th blackout in the UK and the September 28th blackout in Australia, both of which triggered large-scale blackouts due to grid frequency instability. Furthermore, in scenarios where renewable energy is transmitted via multi-terminal DC power, if a three-phase symmetrical fault occurs in the receiving grid, the generated power from the renewable energy source can cause overvoltage events at the renewable energy base due to the interruption of the DC transmission channel.

[0004] Traditional modeling methods focus on low voltage ride-through (LVRT) research, but the dynamic characteristics of HVRT remain insufficient, particularly lacking systematic modeling of the entire fault process. This can lead to control failures or grid disconnection risks for wind turbines in actual operation when facing high voltage surges, threatening grid stability.

[0005] Furthermore, the operating characteristics of receiving-end power grids under high renewable energy penetration rates have changed significantly, with the number of traditional synchronous generators gradually decreasing and the characteristics of low-inertia power systems becoming increasingly pronounced. Under three-phase symmetrical faults, an abnormal rise in the voltage at the common coupling point can trigger a chain reaction, further exacerbating frequency instability and power shortages. Therefore, studying equivalent modeling methods for direct-drive wind turbines in high-voltage ride-through scenarios not only helps reveal their dynamic response patterns but also provides theoretical support for grid fault analysis, wind turbine optimization design, and control strategy development. Summary of the Invention

[0006] The main purpose of the present invention is to provide a high voltage ride through equivalent modeling method and related devices for a direct-drive wind turbine generator system, which can solve the problem of insufficient dynamic characteristic analysis of high voltage ride through in the prior art.

[0007] To achieve the above objectives, the present invention provides a first aspect of a high voltage ride-through equivalent modeling method for a direct-drive wind turbine generator system, the method comprising:

[0008] Establishing a time-varying voltage model of a common coupling point of a new energy base under a three-phase symmetrical fault in a receiving-end power grid; the new energy base at least includes a direct-drive wind turbine; the input end of the receiving-end power grid is electrically connected to the output end of the direct-drive wind turbine; the direct-drive wind turbine at least includes a Chopper circuit;

[0009] Based on the topology of the direct-drive wind turbine generator system, a decoupling analysis is performed on the correlation between the Chopper circuit switching threshold, energy consumption power, and grid-side converter control parameters, and a piecewise mapping equation for output power and AC voltage is constructed under a symmetrical voltage rise scenario; the grid-side converter is used to convert the first electrical energy of the direct-drive wind turbine generator system into the second electrical energy of the receiving grid;

[0010] The transient energy conservation equation is introduced to establish a universal power curve covering the entire fault cycle. The universal power curve is used to characterize the dynamic relationship between the Chopper action threshold, power limit value and voltage recovery rate.

[0011] By integrating the voltage outer loop control characteristics of the grid-side converter and the Chopper energy consumption dynamics, a time-domain analytical expression for the terminal voltage of the direct-drive wind turbine during high voltage ride-through is obtained.

[0012] To achieve the above-mentioned object, the second aspect of the present invention provides a high voltage ride-through equivalent modeling device for a direct-drive wind turbine generator system, the device comprising:

[0013] The first modeling module is used to establish a time-varying voltage model of the common coupling point of a new energy base under a three-phase symmetrical fault in a receiving-end power grid; the new energy base includes at least a direct-drive wind turbine; the input end of the receiving-end power grid is electrically connected to the output end of the direct-drive wind turbine; the direct-drive wind turbine includes at least a Chopper circuit;

[0014] The second modeling module is used to decouple and analyze the correlation between the Chopper circuit switching threshold, energy consumption power, and grid-side converter control parameters based on the topology of the direct-drive wind turbine group, and to construct a piecewise mapping equation between output power and AC voltage in a symmetrical voltage rise scenario; the grid-side converter is used to convert the first electric energy of the direct-drive wind turbine group into the second electric energy of the receiving power grid;

[0015] The third modeling module is used to introduce the transient energy conservation equation and establish a universal power curve covering the entire fault cycle. The universal power curve is used to characterize the dynamic relationship between the Chopper action threshold, power limit value and voltage recovery rate;

[0016] The fourth modeling module is used to integrate the grid-side converter voltage outer loop control characteristics and Chopper energy consumption dynamics to obtain the time-domain analytical expression of the direct-drive wind turbine terminal voltage during high voltage ride-through.

[0017] To achieve the above-mentioned purpose, the third aspect of the present invention provides a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to perform the steps of the method shown in the first aspect.

[0018] To achieve the above-mentioned purpose, the fourth aspect of the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the method shown in the first aspect.

[0019] The embodiments of the present invention have the following beneficial effects:

[0020] The present invention provides a high voltage ride-through equivalent modeling method for a direct-drive wind turbine generator set, the method comprising: establishing a time-varying voltage model of a common coupling point of a new energy base under a three-phase symmetrical fault in a receiving-end power grid; the new energy base at least includes a direct-drive wind turbine generator set; the input end of the receiving-end power grid is electrically connected to the output end of the direct-drive wind turbine generator set; the direct-drive wind turbine generator set at least includes a Chopper circuit; based on the topological structure of the direct-drive wind turbine generator set, decoupling and analyzing the correlation between the Chopper circuit switching threshold, energy consumption power and grid-side converter control parameters, and constructing a piecewise mapping equation of output power and AC voltage under a symmetrical voltage rise scenario; the grid-side converter is used to convert the first electric energy of the direct-drive wind turbine generator set into the second electric energy of the receiving-end power grid; introducing a transient energy conservation equation to establish a universal power curve covering the entire fault cycle, the universal power curve being used to characterize the dynamic relationship between the Chopper action threshold, power limit value and voltage recovery rate; integrating the voltage outer loop control characteristics of the grid-side converter and the Chopper energy consumption dynamics to obtain a time-domain analytical expression of the terminal voltage of the direct-drive wind turbine generator set during the high voltage ride-through process.

[0021] This approach provides a direct-drive wind turbine HVRT equivalent modeling method that considers chopper circuits and control dynamics, overcoming the inadequate analysis of the dynamic characteristics of the entire fault process by traditional modeling methods. Compared to existing modeling methods that typically focus only on a single state or quasi-steady state, this direct-drive wind turbine HVRT equivalent modeling method that considers chopper circuits and control dynamics can more comprehensively capture the voltage and power response behavior of direct-drive wind turbines during HVRT, thereby improving the model's adaptability and prediction accuracy for complex grid fault scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] in:

[0024] Figure 1 This is a flow chart of a high voltage ride-through equivalent modeling method for a direct-drive wind turbine generator system according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of a multi-terminal DC system communication architecture according to an embodiment of the present invention;

[0026] Figure 3 A comparison diagram of a grid-side voltage waveform in an embodiment of the present invention;

[0027] Figure 4 This is a structural block diagram of a high voltage ride-through equivalent modeling device for a direct-drive wind turbine generator system according to an embodiment of the present invention;

[0028] Figure 5 4 is a structural block diagram of a computer device in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] 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 only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] See also Figure 1 , Figure 1This is a flow chart of a high voltage ride-through equivalent modeling method for a direct-drive wind turbine generator system according to an embodiment of the present invention. This method can be applied to both terminals and servers. This embodiment is described by applying it to a terminal as an example. The terminal can be a desktop terminal or a mobile terminal. The mobile terminal can be at least one of a mobile phone, a tablet computer, a laptop computer, etc. The server can be implemented as an independent server or a server cluster consisting of multiple servers. Figure 1 The method shown includes the following steps:

[0031] 101. Establish a time-varying voltage model for the common coupling point of a new energy base under a three-phase symmetrical fault in the receiving power grid;

[0032] It should be noted that this application first establishes a time-varying voltage model of the common coupling point (PCC) of the new energy base under a three-phase symmetrical fault in the receiving power grid to provide boundary conditions for multi-stage modeling.

[0033] Among them, the new energy base includes at least direct-drive wind turbines, which can also be called direct-drive wind turbines.

[0034] The input end of the receiving-end power grid is electrically connected to the output end of the direct-drive wind turbine generator set, that is, the wind power grid is powered by the direct-drive wind turbine generator set to supply power to the receiving-end power grid (load end).

[0035] Among them, the direct-drive wind turbine set includes at least a Chopper circuit, which is also a DC chopper circuit. The Chopper circuit is a power electronic circuit used to protect the system and can be integrated into the direct-drive wind turbine.

[0036] Direct-drive wind turbines also include grid-side converters and machine-side converters. Converters can also be called inverters. The machine-side converter is a power electronic device that connects the wind turbine and the DC bus, responsible for converting the generator's electrical energy into DC power; the grid-side converter is a power electronic device that connects the DC bus and the power grid, responsible for converting DC power into AC power suitable for grid access.

[0037] Specifically, in step 101, the initial power state when commutation fails or locks out is analyzed, and the AC voltage U before the fault is recorded. ac0 and reactive power Q dc0 , where Q dc0 It is the reactive power compensated to the DC transmission system by the filter resistor before the DC transmission system, usually 40% of the active power transmitted by the DC transmission system.

[0038] When the reactive power before the fault is known, the excess reactive power can be calculated based on the reactive power changes before and after the fault. The calculation method is as follows:

[0039] Q surplus =Q dc0-Q loss ;

[0040] Where Q surplus is the excess reactive power, Q loss is the reactive power of the DC transmission system after the fault; Q dc0 is the reactive power of the HVDC transmission system before the fault.

[0041] Establish the equivalent circuit of the public coupling point near the new energy base, and use the system short-circuit capacity S sc Determine the equivalent impedance Z eq for:

[0042]

[0043] Where U n is the AC voltage at the common coupling point, where the system short-circuit capacity S sc It refers to the maximum short-circuit current capability that the power system can provide at the point of common coupling.

[0044] Based on the relationship between reactive power and voltage, calculate the voltage rise amplitude ΔU in the vicinity ac :

[0045]

[0046] Where ΔU ac is the rise of the AC voltage at the common coupling point.

[0047] The voltage after the fault is obtained:

[0048] U ac =U ac0 +ΔU ac

[0049] Where U ac0 is the initial voltage of the receiving-end AC grid before the fault.

[0050] The dynamic response equation is further introduced to describe the change of voltage over time, and the time-varying voltage model is obtained:

[0051] U ac (t) = U ac0 +ΔU ac ·(1-e -t / τ )

[0052] Where t is time, τ is time constant, U ac0 is the initial voltage of the receiving grid before the fault; U ac (t) is the voltage of the receiving end power grid after the fault; ΔU ac is the near-area voltage rise amplitude of the equivalent circuit near the common coupling point of the new energy base.

[0053] It should be noted that the time-varying voltage model established in step 101 describes the voltage variation patterns at the point of common coupling (PCC) of the new energy base under a three-phase symmetrical fault in the receiving grid. These voltage variation patterns form the basis for the analysis and modeling in subsequent steps. These voltage variation patterns will be used in subsequent steps to analyze the switching behavior, power response, and voltage recovery process of the Chopper circuit.

[0054] 102. Based on the topological structure of direct-drive wind turbines, decoupling analysis is performed on the correlation between the Chopper circuit switching threshold, energy consumption power and grid-side converter control parameters, and a piecewise mapping equation between output power and AC voltage is constructed under symmetrical voltage rise scenarios.

[0055] Furthermore, the correlation between the Chopper switching threshold and converter control is analyzed, and a piecewise power-voltage mapping equation is constructed. Specifically, based on the topology of the direct-drive wind turbine, a decoupling analysis is performed on the correlation between the Chopper circuit switching threshold, energy consumption power and grid-side converter control parameters, and a piecewise mapping equation between output power and AC voltage in a symmetrical voltage rise scenario is constructed.

[0056] It is understandable that different direct-drive wind turbines may have different topologies, and pre-acquiring wind turbine parameters enables high voltage ride-through equivalent modeling of different direct-drive wind turbines. The grid-side converter is used to convert the first electrical energy of the direct-drive wind turbine into the second electrical energy of the receiving grid.

[0057] Specifically, the triggering of the Chopper circuit is based on whether the voltage at the common coupling point exceeds a preset threshold, which directly depends on the voltage variation law provided by the time-varying voltage model. In step 102, it is assumed that after a power grid fault occurs, the voltage at the common coupling point abnormally rises to 1.5–2.0 pu of the new energy station (i.e., the above-mentioned new energy base), triggering the high voltage ride-through mechanism. The chopper circuit will be temporarily put into operation (for several thousand milliseconds) to convert excess electrical energy into heat energy through a resistor with short-circuit impedance to protect the system. The trigger signal of the chopper circuit can be set to:

[0058]

[0059] After the Chopper circuit is triggered, the output power of the direct-drive wind turbine will be adjusted according to the voltage change. This adjustment requires the use of a time-varying voltage model to predict the voltage change, thereby determining the power response strategy. Specifically, during the high voltage ride-through period (the corresponding time range is [t0, t2]), when a fault occurs in the power grid and causes the voltage at the common coupling point to rise abnormally, the direct-drive wind turbine needs to maintain stable operation through a control strategy. At this time, the reference value of the active power of the wind turbine can be limited to 0 according to the specific control requirements, or the active power reference value before the fault can be maintained to prevent overpower or grid disconnection risks. The specific control conditions are as follows:

[0060]

[0061] Where: u s is the stator voltage of the direct-drive wind turbine generator set, which is equal to the voltage at the common coupling point of the power grid; u set is the preset voltage threshold for high voltage ride-through, i.e., the Chopper circuit switching threshold; P ref is the active power reference value of the direct-drive wind turbine generator system, P pre is the active power reference value of the direct-drive wind turbine before the fault.

[0062] 103. Introduce the transient energy conservation equation and establish a universal power curve covering the entire fault cycle. The universal power curve is used to characterize the dynamic relationship between the Chopper action threshold, power limit value and voltage recovery rate;

[0063] Furthermore, a power curve covering the entire fault cycle is established to quantify the dynamic relationship between Chopper action and voltage recovery rate. Specifically, the transient energy conservation equation is introduced to establish a universal power curve covering the entire fault cycle. The universal power curve is used to characterize the dynamic relationship between the Chopper action threshold, power limit value, and voltage recovery rate.

[0064] Among them, the transient energy conservation equation needs to use the voltage changes provided by the time-varying voltage model to calculate the energy input and output; the power variation over time is based on the voltage variation law provided by the time-varying voltage model, describing the dynamic behavior of power throughout the fault cycle.

[0065] In step 103, because the time scale of the inner current loop is much smaller than the electromechanical time scale of the outer loop and the inner loop responds faster, the current output by the converter to the grid is approximately equal to the outer loop reference value. The time scale of the grid-side converter is on the order of 10ms, and the PI controller can track its transient process within the electromechanical transient stability time scale of the power system. At the same time, because the response speed of integral control is slower than that of proportional control, the integral phase of the PI controller is ignored when modeling electromechanical transients, resulting in:

[0066]

[0067] Where: i gd 、i gq are the d-axis and q-axis components of the grid-side current, u dc_ref DC voltage reference value of direct-drive fan DC side, u dc is the DC voltage on the DC side of the direct-drive wind turbine, Q g_ref is the direct drive wind turbine reactive power control reference value, Q g is the reactive power of the direct-drive wind turbine, k pu is the DC voltage control proportional control coefficient, k pq is the reactive power proportional control coefficient.

[0068] The DC voltage expression is:

[0069]

[0070] Where C is the DC capacitance value, P dc is the output power of the direct-drive wind turbine side converter, P g Output power of the grid-side converter of the direct-drive wind turbine.

[0071] The complex power S of the direct-drive wind turbine can be written as:

[0072]

[0073] Where S is the complex power of the direct-drive wind turbine, and the general power curve includes the complex power S; P dc is the output power of the direct-drive wind turbine generator set side converter; C is the DC capacitance value; k pu is the DC voltage control proportional control coefficient; u dc_ref is the DC voltage reference value of the direct-drive wind turbine generator set; i gd 、i gq are the d-axis and q-axis components of the grid-side current respectively; Q g_ref is the reference value for reactive power control of direct-drive wind turbines; k pq is the reactive power proportional control coefficient.

[0074] 104. By integrating the voltage outer loop control characteristics of the grid-side converter and the Chopper energy consumption dynamics, the time domain analytical expression of the terminal voltage of the direct-drive wind turbine during high voltage ride-through is obtained.

[0075] Finally, the converter control and Chopper dynamics are integrated to derive the time domain analytical model of the terminal voltage during HVRT. Specifically, the voltage outer loop control characteristics of the grid-side converter and the Chopper energy consumption dynamics are integrated to derive the time domain analytical expression of the terminal voltage during HVRT. The time domain analytical expression of the terminal voltage of the direct-drive wind turbine during HVRT is obtained.

[0076] See also Figure 2 , Figure 2 This figure shows a multi-terminal DC system communication architecture according to an embodiment of the present invention. In the normal state, the wind turbine operates as a constant current source, outputting current to the grid. In the fault state, the converter switches to a controlled voltage source, the chopper is operational, the grid-side converter may be locked, and the system maintains stability by regulating reactive power. The DC system is responsible for the transmission and conversion of electrical energy.

[0077] In step 104, if Figure 2 In the electromechanical transient process of the direct drive process shown in the figure, when an overvoltage occurs and the chopper is turned on, but the grid-side output current is less than the converter current limit value, the grid-side converter is in an unblocked state. At this time, the analytical expression of the grid-side voltage is:

[0078]

[0079] Where U g is the grid-connected voltage amplitude of the converter on the grid side of the direct-drive wind turbine, I g is the AC grid-connected current amplitude, P dc is the output power of the direct-drive wind turbine generator set side converter; C is the DC capacitance value; k pu is the DC voltage control proportional control coefficient; u dc_ref is the DC voltage reference value of the direct-drive wind turbine generator set; i gd 、i gq are the d-axis and q-axis components of the grid-side current respectively; Q g_ref is the reference value for reactive power control of direct-drive wind turbines; k pq is the reactive power proportional control coefficient.

[0080] It should be noted that 1) the present invention proposes an equivalent modeling method for high voltage ride-through of direct-drive wind turbines considering the chopper circuit and control dynamics, and describes the dynamic interaction between the Chopper circuit switching and the converter control through time domain equations, breaking through the limitations of traditional single-stage modeling and realizing accurate characterization of the dynamic characteristics of the entire fault cycle; 2) the present invention establishes a coupling model of the energy consumption power of the Chopper circuit and the PI parameters of the grid-side converter voltage loop, revealing the regulation mechanism of the energy consumption resistor switching threshold on the power-voltage transient response, and solving the model distortion problem of traditional methods that ignore the dynamic characteristics of power electronic devices; 3) based on the multi-time-scale power balance theory, the present invention constructs an adaptive power curve containing the Chopper action characteristics, quantifies the correlation between the power limit and the voltage recovery rate in each stage of the fault, and significantly improves the model generalization ability under complex working conditions.

[0081] Among them, the comparison results of the grid-side voltage analytical model and simulation model of the direct-drive wind turbine under the high voltage ride-through scenario are as follows: Figure 3A comparison diagram of a grid-side voltage waveform in an embodiment of the present invention is shown in FIG. Figure 3 As shown in the figure, the waveforms of the two curves are very similar, both are sinusoidal, indicating that the grid-side voltage changes in the two cases follow the same pattern, which indicates the correctness of the established model.

[0082] It should be noted that the present invention has the following beneficial effects: 1. The equivalent modeling method for high voltage ride-through of direct-drive wind turbines considering chopper circuits and control dynamics proposed in the present invention reveals the cross-time scale interaction mechanism of Chopper circuit switching and converter control, provides a universal theoretical tool for dynamic characteristic analysis of fault ride-through of new energy units, and promotes the deepening of theoretical research on transient stability of power electronic power systems towards multi-physical field coupling; 2. The equivalent modeling method for high voltage ride-through of direct-drive wind turbines considering chopper circuits and control dynamics proposed in the present invention guides engineers to optimize the matching design of energy consumption resistor parameters and converter control parameters by accurately quantifying the dynamic correlation law of Chopper energy consumption threshold, power limit and voltage recovery rate, reduces hardware redundancy, shortens the verification cycle of high voltage ride-through capability of wind turbines, and significantly reduces R&D costs. 3. The present invention proposes an equivalent modeling method for high voltage ride-through of direct-drive wind turbines that considers chopper circuits and control dynamics. The constructed model strictly complies with the requirements of GB / T 19963-2021 for voltage tolerance curves and power recovery rates. It can accurately predict the dynamic behavior of the unit in the scenario of grid voltage surge (+10% to +30% per unit value), providing a high-confidence simulation tool for wind farm grid-connected certification, avoiding construction delays and waste of resources caused by repeated on-site testing.

[0083] The present invention provides a high voltage ride-through equivalent modeling method for a direct-drive wind turbine generator set, and proposes a high voltage ride-through equivalent modeling method for a direct-drive wind turbine generator set that takes into account chopper circuits and control dynamics, specifically for transient modeling of fault characteristics of new energy grid-connected systems. The present invention decomposes the high voltage ride-through process into four stages: a steady state before the fault occurs, a quasi-steady state during the fault duration, a recovery process after the fault is cleared, and a steady state after the recovery is completed. The invention combines time domain analysis with control equations to accurately describe the grid-side voltage characteristics after taking into account the chopper circuit and control characteristics, thereby overcoming the problem that traditional modeling methods are insufficient in analyzing the dynamic characteristics of the entire fault process. Compared to the modeling methods in the prior art that usually only focus on a single state or quasi-steady state, the high voltage ride-through equivalent modeling method for a direct-drive wind turbine generator set that takes into account chopper circuits and control dynamics can more comprehensively capture the voltage and power response behavior of the direct-drive wind turbine generator set during the high voltage ride-through process, thereby improving the model's adaptability and prediction accuracy to complex power grid fault scenarios.

[0084] See also Figure 4 , Figure 4FIG. 1 is a structural block diagram of a high voltage ride-through equivalent modeling device for a direct-drive wind turbine generator system according to an embodiment of the present invention. Figure 4 The apparatus shown comprises:

[0085] The first modeling module 401 is used to establish a time-varying voltage model of a common coupling point of a new energy base under a three-phase symmetrical fault in a receiving-end power grid; the new energy base includes at least a direct-drive wind turbine; the input end of the receiving-end power grid is electrically connected to the output end of the direct-drive wind turbine; the direct-drive wind turbine includes at least a Chopper circuit;

[0086] The second modeling module 402 is configured to perform a decoupling analysis of the correlation between the Chopper circuit switching threshold, energy consumption power, and grid-side converter control parameters based on the topology of the direct-drive wind turbine generator set, and to construct a piecewise mapping equation between output power and AC voltage in a symmetrical voltage rise scenario; the grid-side converter is configured to convert the first electric energy of the direct-drive wind turbine generator set into the second electric energy of the receiving power grid;

[0087] The third modeling module 403 is used to introduce the transient energy conservation equation and establish a universal power curve covering the entire fault cycle. The universal power curve is used to characterize the dynamic relationship between the Chopper action threshold, the power limit value and the voltage recovery rate;

[0088] The fourth modeling module 404 is used to integrate the voltage outer loop control characteristics of the grid-side converter and the Chopper energy consumption dynamics to obtain a time-domain analytical expression of the terminal voltage of the direct-drive wind turbine during the high voltage ride-through process.

[0089] The present invention provides a high voltage ride-through equivalent modeling device for a direct-drive wind turbine generator set, the device comprising: a first modeling module: for establishing a time-varying voltage model of a common coupling point of a new energy base under a three-phase symmetrical fault in a receiving-end power grid; the new energy base at least comprises a direct-drive wind turbine generator set; the input end of the receiving-end power grid is electrically connected to the output end of the direct-drive wind turbine generator set; the direct-drive wind turbine generator set at least comprises a Chopper circuit; a second modeling module: for decoupling and analyzing the correlation between the switching threshold of the Chopper circuit, the energy consumption power and the control parameters of the grid-side converter based on the topological structure of the direct-drive wind turbine generator set, and constructing a symmetrical electric The grid-side converter is used to convert the first electric energy of the direct-drive wind turbine into the second electric energy of the receiving power grid; the third modeling module is used to introduce the transient energy conservation equation and establish a universal power curve covering the entire fault cycle. The universal power curve is used to characterize the dynamic relationship between the Chopper action threshold, power limit value and voltage recovery rate; the fourth modeling module is used to integrate the voltage outer loop control characteristics of the grid-side converter and the Chopper energy consumption dynamics to obtain the time domain analytical expression of the terminal voltage of the direct-drive wind turbine during the high voltage ride-through process.

[0090] This approach provides a direct-drive wind turbine HVRT equivalent modeling method that considers chopper circuits and control dynamics, overcoming the inadequate analysis of the dynamic characteristics of the entire fault process by traditional modeling methods. Compared to existing modeling methods that typically focus only on a single state or quasi-steady state, this direct-drive wind turbine HVRT equivalent modeling method that considers chopper circuits and control dynamics can more comprehensively capture the voltage and power response behavior of direct-drive wind turbines during HVRT, thereby improving the model's adaptability and prediction accuracy for complex grid fault scenarios.

[0091] Figure 5 FIG1 shows an internal structure diagram of a computer device in an embodiment. The computer device can be a terminal or a server. Figure 5 As shown, the computer device includes a processor, a memory, and a network interface connected via a system bus. The memory includes a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and may also store a computer program. When the computer program is executed by the processor, the processor can implement the above method. The internal memory may also store a computer program. When the computer program is executed by the processor, the processor can implement the above method. It will be understood by those skilled in the art that Figure 5 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0092] In one embodiment, a computer device is provided, comprising a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor performs the following Figure 1 Steps of the method shown.

[0093] In one embodiment, a computer-readable storage medium is provided, which stores a computer program. When the computer program is executed by a processor, the processor is caused to execute the following Figure 1 Steps of the method shown.

[0094] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiments can be implemented by instructing the relevant hardware through a computer program. The program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0095] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A high voltage ride-through equivalent modeling method for a direct-drive wind turbine generator system, characterized in that: The method comprises: Establishing a time-varying voltage model of a common coupling point of a new energy base under a three-phase symmetrical fault in a receiving-end power grid; the new energy base at least includes a direct-drive wind turbine; the input end of the receiving-end power grid is electrically connected to the output end of the direct-drive wind turbine; the direct-drive wind turbine at least includes a Chopper circuit; Based on the topology of the direct-drive wind turbine generator system, a decoupling analysis is performed on the correlation between the Chopper circuit switching threshold, energy consumption power, and grid-side converter control parameters, and a piecewise mapping equation for output power and AC voltage is constructed under a symmetrical voltage rise scenario; the grid-side converter is used to convert the first electrical energy of the direct-drive wind turbine generator system into the second electrical energy of the receiving grid; The transient energy conservation equation is introduced to establish a universal power curve covering the entire fault cycle. The universal power curve is used to characterize the dynamic relationship between the Chopper action threshold, power limit value and voltage recovery rate. By integrating the voltage outer loop control characteristics of the grid-side converter and the Chopper energy consumption dynamics, a time-domain analytical expression for the terminal voltage of the direct-drive wind turbine during high voltage ride-through is obtained.

2. The method according to claim 1, characterized in that The time-varying voltage model includes the following mathematical expressions: U ac (t)=U ac0 +ΔU ac ·(1-e -t / τ ); Where U ac0 is the initial voltage of the receiving grid before the fault; U ac (t) is the voltage of the receiving-end power grid after the fault; ΔU ac is the voltage rise amplitude in the vicinity of the common coupling point of the new energy base, t is time, and τ is the time constant.

3. The method according to claim 2, characterized in that The near-zone voltage rise amplitude includes the following mathematical expression: Where ΔU ac is the voltage rise amplitude of the equivalent circuit near the common coupling point of the new energy base, Q surplus is the excess reactive power; S sc The system short-circuit capacity refers to the maximum short-circuit current that the power system can provide at the common coupling point.

4. The method according to claim 3, characterized in that The reactive excess includes the following mathematical expression: Q surplus =Q dc0 -Q loss ; Where Q surplus is the excess reactive power, Q loss is the reactive power of the DC transmission system after the fault; Q dc0 is the reactive power of the HVDC transmission system before the fault.

5. The method according to claim 1, characterized in that: The segmented mapping equation includes the following mathematical expressions: Where u s is the stator voltage of the direct-drive wind turbine generator set, which is equal to the voltage at the common coupling point of the power grid; u set is the Chopper circuit switching threshold, P ref is the active power reference value of the direct-drive wind turbine generator system, P pre is the active power reference value of the direct-drive wind turbine before the fault.

6. The method according to claim 1, characterized in that The general power curve includes the following mathematical expression: Where, S is the complex power of the direct-drive wind turbine; P dc is the output power of the direct-drive wind turbine generator set side converter; C is the DC capacitance value; k pu is the DC voltage control proportional control coefficient; u dc_ref is the DC voltage reference value of the direct-drive wind turbine generator set; i gd 、i gq are the d-axis and q-axis components of the grid-side current respectively; Q g_ref is the reference value for reactive power control of direct-drive wind turbines; k pq is the reactive power proportional control coefficient.

7. The method according to claim 1, characterized in that: The time domain analytical expression of the terminal voltage includes the following mathematical expression: Where U g is the grid-connected voltage amplitude of the converter on the grid side of the direct-drive wind turbine, I g is the AC grid-connected current amplitude, P dc is the output power of the direct-drive wind turbine generator set side converter; C is the DC capacitance value; k pu is the DC voltage control proportional control coefficient; u dc_ref is the DC voltage reference value of the direct-drive wind turbine generator set; i gd 、i gq are the d-axis and q-axis components of the grid-side current respectively; Q g_ref is the reference value for reactive power control of direct-drive wind turbines; k pq is the reactive power proportional control coefficient.

8. A high voltage ride-through equivalent modeling device for a direct-drive wind turbine generator system, characterized in that: The device comprises: The first modeling module is used to establish a time-varying voltage model of the common coupling point of a new energy base under a three-phase symmetrical fault in a receiving-end power grid; the new energy base includes at least a direct-drive wind turbine; the input end of the receiving-end power grid is electrically connected to the output end of the direct-drive wind turbine; the direct-drive wind turbine includes at least a Chopper circuit; The second modeling module is used to decouple and analyze the correlation between the Chopper circuit switching threshold, energy consumption power, and grid-side converter control parameters based on the topology of the direct-drive wind turbine group, and to construct a piecewise mapping equation between output power and AC voltage in a symmetrical voltage rise scenario; the grid-side converter is used to convert the first electric energy of the direct-drive wind turbine group into the second electric energy of the receiving power grid; The third modeling module is used to introduce the transient energy conservation equation and establish a universal power curve covering the entire fault cycle. The universal power curve is used to characterize the dynamic relationship between the Chopper action threshold, power limit value and voltage recovery rate; The fourth modeling module is used to integrate the grid-side converter voltage outer loop control characteristics and Chopper energy consumption dynamics to obtain the time-domain analytical expression of the direct-drive wind turbine terminal voltage during high voltage ride-through.

9. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 7.

10. A computer device comprising a memory and a processor, characterized in that: The memory stores a computer program, and when the computer program is executed by the processor, the processor is caused to perform the steps of the method according to any one of claims 1 to 7.

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