Transient unbalance high-voltage ride-through method and device for direct-drive permanent magnet wind generating set

Abstract

The invention discloses a transient unbalance high-voltage ride-through method and device for a direct-drive permanent magnet wind generating set, and relates to the technical field of safe and stable operation of wind power generation in new energy, and the method comprises the steps: constructing a virtual synchronous generator model of an inverter; based on the virtual synchronous generator model of the inverter, performing unbalance analysis on a grid-connected point of the direct-driven permanent magnet synchronous generator set by using an instantaneous symmetric component method and Clark coordinate change, and determining complex power; constructing a positive and negative sequence voltage-current double closed-loop control strategy; a current inner loop in the positive and negative sequence voltage-current double closed-loop control strategy is optimized into sliding mode control, and a positive and negative sequence voltage-current double closed-loop sliding mode control strategy is obtained; executing a positive and negative sequence voltage-current double closed-loop sliding mode control strategy based on a maximum torque control mode; according to the invention, a positive and negative sequence voltage-current double closed-loop control strategy is constructed. While the high-voltage fault ride-through capability of the wind generating set is improved, the frequency stability capability is maintained.

Description

Technical Field

[0001] The present application relates to the technical field of safe and stable operation of wind power generation in renewable energy, and in particular to a method and device for transient unbalanced high voltage ride-through of a direct-drive permanent magnet wind generator set. Background Art

[0002] As the proportion of new energy and wind power penetration rate continue to increase, the safe and stable operation of the power system faces new challenges. Actively facing the complete stability challenges faced by large-scale new energy grid-connected operation has become a common responsibility and obligation that the power grid and the new energy industry cannot avoid. The problem of safe and stable operation of wind turbine voltage caused by external grid faults has become one of the main bottlenecks restricting the large-scale, clustered and intelligent development of wind power. In recent years, a lot of research has been conducted on voltage fault ride-through of different units. In the actual operation of the power system, the three-phase unbalanced high voltage generated by the cut-out of large-capacity loads and single-phase grounding faults has a transient impact on the wind turbine. Therefore, it is urgent to develop methods to enhance the ability of wind turbines to ride through unbalanced high voltages in grid-connected operation to improve the stability of power system operation.

[0003] Enhancing the fault ride-through capability of wind turbines is an effective way to solve the problem of voltage rise at the grid connection point caused by grid faults or disturbances. At present, the control of high voltage ride-through for wind turbines can be classified according to different control areas of the machine side, DC bus, and grid side. However, most of them involve three-phase symmetrical high voltage fault ride-through, and secondly, they only implement corresponding control for the single fault ride-through problem of voltage fault ride-through. In the actual power system, when a fault or disturbance occurs, the ideal three-phase symmetrical high voltage does not appear. Secondly, multiple factors such as frequency ride-through need to be considered. Therefore, while improving the high voltage fault capability of wind turbines, it is also necessary to consider the ability to maintain frequency stability and further improve the fault ride-through capability of wind turbines. Summary of the invention

[0004] The purpose of the present application is to provide a method and device for transient unbalanced high voltage ride-through of a direct-drive permanent magnet wind turbine generator set, which can improve the high voltage fault ride-through capability of the wind turbine generator set while maintaining the frequency stability capability.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides a method for transient unbalanced high voltage ride-through of a direct-drive permanent magnet wind turbine generator set, comprising:

[0007] The grid-side inverter of the direct-drive permanent magnet synchronous wind turbine generator is simulated as a virtual synchronous generator, and a virtual synchronous generator model of the inverter is constructed;

[0008] Based on the virtual synchronous generator model of the inverter, construct an active loop control structure and a reactive loop control structure;

[0009] Determining a virtual synchronous generator reference voltage based on the active loop control structure and the reactive loop control structure;

[0010] Based on the virtual synchronous generator reference voltage, an unbalance analysis is performed on the direct-drive permanent magnet synchronous generator set at the grid connection point using the instantaneous symmetrical component method and Clarke coordinate change to obtain the positive and negative sequence components of the current and the positive and negative sequence components of the voltage;

[0011] Determine the complex power based on the positive and negative sequence components of the current and the positive and negative sequence components of the voltage; the complex power is used to determine the influence of different power components on the power oscillation of the grid-side inverter under uneven voltage;

[0012] Based on the influence of different power components on the power oscillation of the grid-side inverter under uneven voltage, a positive and negative sequence voltage-current dual closed-loop control strategy is constructed;

[0013] The current inner loop in the positive and negative sequence voltage-current dual closed-loop control strategy is optimized into a sliding mode control, and a positive and negative sequence voltage-current dual closed-loop sliding mode control strategy is obtained;

[0014] The positive and negative sequence voltage-current dual closed-loop sliding mode control strategy is executed based on the maximum torque control method.

[0015] Optionally, the virtual synchronous generator model of the inverter is:

[0016]

[0017] Where J is the moment of inertia, ω is the angular frequency of the virtual synchronous generator, t is time, T m is the mechanical torque of the virtual synchronous generator, T e is the electromagnetic torque of the virtual synchronous generator, T d is the damping torque of the virtual synchronous generator, D is the damping coefficient, ω0 is the angular frequency of the power grid, P e is the electromagnetic power, e a 、e b 、e c is the three-phase potential of the virtual synchronous generator, i a 、i b 、i c is the three-phase output current of the virtual synchronous generator.

[0018] Optionally, the active loop control structure is:

[0019]

[0020] Among them, P refis the active power reference value;

[0021] The reactive loop control structure is:

[0022]

[0023] Among them, Q ref is the reactive power reference value, Q e is the output reactive power, K is the integral coefficient, E is the virtual potential, e n is the rated voltage of the machine end.

[0024] Optionally, the virtual synchronous generator reference voltage is:

[0025]

[0026] Among them, e ref is the reference voltage of the virtual synchronous generator, and θ is the voltage phase angle of the active loop output.

[0027] Optionally, the complex power is: S=P g +jQ g ;

[0028] Where S is the complex power, P g is the active power, Q g is the reactive power.

[0029] Optionally, the active power includes an average value P0 of the active power, a second harmonic sinusoidal component P s2 And the active power second harmonic cosine component P c2 ; Reactive power includes the average value of reactive power Q0, the second harmonic sinusoidal component of reactive power Q s2 And the reactive power second harmonic cosine component Q c2 ;

[0030] The average value P0 of the active power, the second harmonic sinusoidal component P s2 , the active power second harmonic cosine component P c2 The reactive power includes the average value of the reactive power Q0, the second harmonic sinusoidal component of the reactive power Q s2 and the reactive power second harmonic cosine component Q c2 Both are controlled by the positive and negative sequence components of the current and the positive and negative sequence components of the voltage.

[0031] Optionally, the positive-negative sequence voltage-current dual closed-loop control strategy includes: a current command value when the power grid is in a normal operating state and a negative-sequence current command value when the power grid is in an unbalanced high voltage state;

[0032] The current command value under the normal operation state of the power grid is:

[0033]

[0034] in, are all current command values ​​under normal grid operation, R is the equivalent resistance of the power device on the grid-side inverter, L is the filter inductance on the grid-side inverter, are the reference voltage command values ​​calculated by the virtual synchronous generator. All are positive sequence components of voltage;

[0035] The negative sequence current command value of the power grid under the unbalanced high voltage state is:

[0036]

[0037] in, and , are all negative sequence components of voltage.

[0038] Optionally, the sliding mode control includes:

[0039]

[0040] Among them, S1 is the linear sliding surface, C1, C2, C3 and C4 are all constants, sgn is the sign function, and is the negative sequence current differential, is the negative sequence current deviation in the dq coordinate system, is the negative sequence current in the dq coordinate system, is the negative sequence current command value in the dq coordinate system.

[0041] Optionally, the maximum torque control mode is:

[0042]

[0043] Among them, u sd , is the voltage component of the generator in the d-axis direction, R s is the stator resistance, u sq , is the voltage component of the generator in the q-axis direction, i sd , is the current component of the generator in the d-axis direction, i sq is the current component of the generator in the q-axis direction, L sd , is the inductance component of the generator in the d-axis direction, L sq is the inductance component of the generator in the q-axis direction, ω s , is the synchronous angular velocity of the permanent magnet motor, ψ f It is the synchronous rotor flux of permanent magnet motor.

[0044] In a second aspect, the present application provides a computer device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-mentioned method for transient unbalanced high voltage ride-through of a direct-drive permanent magnet wind turbine generator set.

[0045] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0046] The present application provides a method and device for transient unbalanced high voltage riding of a direct-drive permanent magnet wind turbine generator set. Aiming at the energy imbalance and power fluctuation problems when the grid voltage is unbalanced and transient high voltage occurs when the direct-drive permanent magnet synchronous wind turbine generator set is connected to the grid, the present application effectively enables the grid-side inverter of the direct-drive permanent magnet synchronous generator set to maintain stable power output, stable frequency, fast reactive support voltage recovery speed and accurate control under different degrees of unbalanced high voltage conditions by accurately analyzing the impact of transient shock on the grid voltage when the grid voltage is unbalanced. The machine-side converter adopts the maximum torque control method, and realizes the maximum utilization of wind energy through the dual closed-loop control of the speed outer loop and the current inner loop. The fault riding capability and grid-connected operation stability of the grid-connected system of the permanent magnet direct-drive synchronous wind turbine set are improved when the grid-connected system is connected to the unbalanced high voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0048] Figure 1 This is a flow chart of a method for transient unbalanced high voltage ride-through of a direct-drive permanent magnet wind turbine generator set in one embodiment of the present application.

[0049] Figure 2 This is a control principle diagram of the machine-side converter in one embodiment of the present application.

[0050] Figure 3 This is a schematic diagram of the power regulation principle of the grid-side inverter in one embodiment of the present application.

[0051] Figure 4 This is a schematic diagram of the grid-side inverter control principle in one embodiment of the present application.

[0052] Figure 5 It is a structural schematic diagram of a computer device in one embodiment of the present application. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0054] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0055] In an exemplary embodiment, Figure 1 As shown, a method for transient unbalanced high voltage ride-through of a direct-drive permanent magnet wind turbine generator set is provided, comprising:

[0056] Step 101: Simulate the grid-side inverter of the direct-drive permanent magnet wind turbine generator as a virtual synchronous generator, and construct a virtual synchronous generator model of the inverter.

[0057] Step 102: construct an active loop control structure and a reactive loop control structure based on a virtual synchronous generator model of the inverter.

[0058] Step 103: Determine the virtual synchronous generator reference voltage based on the active loop control structure and the reactive loop control structure.

[0059] Step 104: Based on the virtual synchronous generator reference voltage, an unbalance analysis is performed on the direct-drive permanent magnet synchronous generator set at the grid connection point using the instantaneous symmetrical component method and Clarke coordinate change to obtain the positive and negative sequence components of the current and the positive and negative sequence components of the voltage.

[0060] Step 105: Determine the complex power based on the positive and negative sequence components of the current and the positive and negative sequence components of the voltage. The complex power is used to determine the impact of different power components on the power oscillation of the grid-side inverter under uneven voltage.

[0061] Step 106: Based on the influence of different power components on the power oscillation of the grid-side inverter under uneven voltage, a positive and negative sequence voltage-current dual closed-loop control strategy is constructed.

[0062] Step 107: Optimize the current inner loop in the positive and negative sequence voltage-current dual closed-loop control strategy into sliding mode control to obtain the positive and negative sequence voltage-current dual closed-loop sliding mode control strategy.

[0063] Step 108: Execute the positive and negative sequence voltage-current dual closed-loop sliding mode control strategy based on the maximum torque control method.

[0064] The virtual synchronous generator model of the inverter is:

[0065]

[0066] Where J is the moment of inertia, ω is the angular frequency of the virtual synchronous generator, t is time, T m is the mechanical torque of the virtual synchronous generator, T e is the electromagnetic torque of the virtual synchronous generator, T d is the damping torque of the virtual synchronous generator, D is the damping coefficient, ω0 is the angular frequency of the power grid, P e is the electromagnetic power, e a 、e b 、e c is the three-phase potential of the virtual synchronous generator, i a 、i b 、i c is the three-phase output current of the virtual synchronous generator.

[0067] The active loop control structure is:

[0068]

[0069] Among them, P ref is the active power reference value.

[0070] The reactive loop control structure is:

[0071]

[0072] Among them, Q ref is the reactive power reference value, Q e is the output reactive power, K is the integral coefficient, E is the virtual potential, e n is the rated voltage of the machine end.

[0073] The reference voltage of the virtual synchronous generator is:

[0074]

[0075] Among them, e ref is the reference voltage of the virtual synchronous generator, and θ is the voltage phase angle of the active loop output.

[0076] The complex power is:

[0077] S=P g +jQ g .

[0078] Where S is the complex power, P g is the active power, Q g is the reactive power.

[0079] Active power includes the average value of active power P0, the second harmonic sinusoidal component of active power P s2 And the active power second harmonic cosine component Pc2 Reactive power includes the average value of reactive power Q0, the second harmonic sinusoidal component of reactive power Q s2 And the reactive power second harmonic cosine component Q c2 .

[0080] The average value of active power P0, the second harmonic sinusoidal component of active power P s2 , active power second harmonic cosine component P c2 , reactive power includes the average value of reactive power Q0, the second harmonic sinusoidal component of reactive power Q s2 And the reactive power second harmonic cosine component Q c2 Both are controlled by the positive and negative sequence components of current and the positive and negative sequence components of voltage.

[0081] The positive and negative sequence voltage-current dual closed-loop control strategy includes: a current command value under normal grid operation and a negative sequence current command value under unbalanced high voltage grid operation.

[0082] The current command value under normal operation of the power grid is:

[0083]

[0084] in, are all current command values ​​under normal grid operation, R is the equivalent resistance of the power device on the grid-side inverter, L is the filter inductance on the grid-side inverter, are the reference voltage command values ​​calculated by the virtual synchronous generator. They are all positive sequence components of voltage.

[0085] The negative sequence current command value of the power grid under unbalanced high voltage state is:

[0086]

[0087] in, , are all negative sequence components of voltage.

[0088] Sliding mode control includes:

[0089]

[0090] Among them, S1 is the linear sliding surface, C1, C2, C3 and C4 are all constants, sgn is the sign function, is the negative sequence current differential, is the negative sequence current deviation in the dq coordinate system, is the negative sequence current in the dq coordinate system, is the negative sequence current command value in the dq coordinate system.

[0091] The maximum torque control mode is:

[0092]

[0093] Among them, u sd , is the voltage component of the generator in the d-axis direction, R s is the stator resistance, u sq , is the voltage component of the generator in the q-axis direction, i sd , is the current component of the generator in the d-axis direction, i sq is the current component of the generator in the q-axis direction, L sd , is the inductance component of the generator in the d-axis direction, L sq is the inductance component of the generator in the q-axis direction, ω s , is the synchronous angular velocity of the permanent magnet motor, ψ f It is the synchronous rotor flux of permanent magnet motor.

[0094] In an exemplary embodiment, a method for transient unbalanced high voltage ride-through of a direct-drive permanent magnet wind turbine generator set is provided, and the method has the following specific steps:

[0095] S1. The grid-side inverter of the direct-drive permanent magnet synchronous wind turbine generator is simulated as a virtual synchronous generator, and a virtual synchronous generator model of the inverter is established. Specifically, the grid-side inverter is equivalent to a synchronous generator of the second-order model, and the virtual moment of inertia J and damping coefficient D are introduced through the mechanical equation and electromagnetic torque equation of the virtual synchronous generator. Figure 2 In, ω sref + represents the reference value of the angular velocity of the permanent magnet synchronous generator, ω r represents the angular velocity of the permanent magnet synchronous generator, i sdref represents the d-axis current reference value of the permanent magnet synchronous generator, PI represents the pi control algorithm (proportional integral operation), θ r represents the electrical angle of the permanent magnet synchronous generator rotor, dq represents the two-phase rotating synchronous coordinate system, αβ represents the two-phase stationary coordinate system, abc represents the three-phase stationary coordinate system, and u sα represents the α-axis voltage component of the two-phase stationary coordinate system of the permanent magnet synchronous generator, u sβ It represents the β-axis voltage component of the two-phase stationary coordinate system of the permanent magnet synchronous generator, SVPWM represents space vector pulse width modulation, MSC represents model self-correction composite active disturbance rejection control, and D-PMSG represents direct-drive permanent magnet synchronous generator.

[0096] like Figure 2 , its mathematical equation is as follows:

[0097]

[0098] S2. Establish the regulation control strategy of the active power and frequency, reactive power and voltage of the virtual synchronous generator (VSG), and establish the control structure of the active loop and reactive loop. The specific control structure is established according to the mathematical equations of the active loop and reactive loop, and the mathematical equations of the active loop and reactive loop are as follows.

[0099]

[0100] The active loop is the active power reference value P ref , electromagnetic power P e , the angular frequency ω of the virtual synchronous generator, and the angular frequency ω0 of the power grid. The reactive loop is the reactive power reference value Q ref , virtual potential E, output reactive power Q e With the rated voltage of the machine end n The relationship between them is K, and the integral coefficient. According to the above formula, the active and reactive control structure of VSG is established as follows: Figure 3 As shown: where U T is the per unit value of the grid-connected point detection voltage, I N is the rated current of the wind turbine, k1 is the dynamic reactive current proportional coefficient, U dc is the DC bus voltage, is the DC bus voltage reference value, T ref is the electromagnetic torque reference value, s is the complex frequency domain variable, e ref It is the reference voltage of virtual synchronous generator.

[0101] S3. The voltage phase angle θ output by the active loop in S2 is combined with the virtual electromotive force E output by the reactive loop to obtain the reference voltage of the virtual synchronous generator.

[0102] S4. Perform unbalance analysis on the direct-drive permanent magnet synchronous generator set at the grid connection point, and obtain the positive and negative sequence components of the voltage and current through the instantaneous symmetrical component method and Clarke coordinate change.

[0103] S5. Calculate the complex power of the grid-side inverter using the instantaneous power theory according to S4, and analyze the influence of each power component on the power oscillation of the grid-side inverter under uneven voltage. The real part is the active power, which includes the average value of the active power P0 and the second harmonic sine of the active power P s2 , cosine P c2 The imaginary part is the average value of reactive power Q0 and the second harmonic sine wave Q s2 , cosine Q c2 Quantity.

[0104] S6. Based on the analysis of S5 that the unbalanced voltage causes power oscillation on the grid-side inverter, establish coordinated control of current and power. The specific control is to control the positive and negative sequence voltages and positive and negative sequence current To achieve the average value of active power P0, active power second harmonic sine P s2 , cosine P c2 The average value of the reactive power Q0 and the second harmonic sine wave Q s2 , cosine Q c2 Portion control.

[0105] S7. Based on S6, the positive and negative sequence current and voltage control command values ​​are further derived, and the positive and negative sequence voltage and current dual closed-loop control is established to generate the virtual synchronous generator reference voltage command value for PWM pulse width modulation, thereby controlling the stability of the inverter's active power and frequency under unbalanced high voltage, and the reactive power supports the recovery of the grid voltage. Its control command value includes the current command value under normal grid operation and the negative sequence current command value during unbalanced high voltage fault. The voltage and current dual closed loop uses the feedforward decoupling PI loop to convert the positive and negative sequence currents into corresponding positive and negative sequence voltages, and finally synthesizes the reference voltage for pulse width modulation.

[0106] The calculation formula of the current command value under normal operation of the power grid is as follows:

[0107]

[0108] in is the reference voltage command value calculated by the virtual synchronous generator. L and R are the filter inductance and equivalent resistance of the power device on the grid-side inverter side, respectively.

[0109] The calculation formula of the negative sequence current command value of the power grid under unbalanced high voltage state is as follows:

[0110]

[0111] The negative sequence component current inner loop is optimized to sliding mode control, which uses the superior control stability of sliding mode control under parameter changes and external disturbances to improve the operating stability of the grid-side inverter. ( Respectively represent the negative sequence voltage vector of the virtual synchronous generator potential in dq coordinates), output variable Input variables ( Respectively represent the negative sequence current vector of the virtual synchronous generator output current in dq coordinates), then the system expression of the negative sequence current can be expressed as follows:

[0112]

[0113] Set the negative sequence current sliding mode controller, and the linear sliding mode surface expression is as follows:

[0114]

[0115] Among them, C i >0, i=1,2,3,4, sgn is the sign function. The following control strategy is designed according to the sliding surface to ensure that the system tends to be stable in a finite time:

[0116]

[0117] In the formula, is the differential estimate.

[0118] The maximum torque control method of the machine-side converter makes the stator current DC component i sd Minimum, that is, let i sd =0, the motor produces maximum torque. Figure 4 In the figure, D1 to D6 are diodes, T1 to T6 are insulated gate bipolar transistors (IGBT), C is the equivalent capacitance of the three-phase line to ground, i ac is the equivalent capacitance current relative to ground, i bc is the equivalent capacitance current of phase b to ground, i cc is the equivalent capacitance current of c relative to ground, i ga is the grid phase a current, i gb is the grid phase b current, i gc is the grid phase c current, R g is the equivalent resistance of the power grid, u a is the equivalent power supply of phase a of the power grid, L g is the equivalent inductance of the power grid, u b is the equivalent power supply of phase b of the power grid, u c is the equivalent power source of phase c of the power grid, N is the neutral point, is the d-axis voltage reference value of the virtual synchronous generator, is the q-axis voltage reference value of the virtual synchronous generator, such as Figure 4 , the voltage equation of PMSG can be simplified under the rotating coordinates d and q axes as follows:

[0119]

[0120] Among them, u sd 、u sq 、i sd 、i sq , L sd , L sq They are the voltage, current components and inductance values ​​of the generator in the d-axis and q-axis directions respectively. s, f are the synchronous angular velocity and rotor flux of the permanent magnet motor respectively.

[0121] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 5 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. Among them, the processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for transient unbalanced high voltage crossing of a direct-drive permanent magnet wind turbine generator set is implemented.

[0122] Those skilled in the art will understand 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 those shown in the figure, or combine certain components, or have a different arrangement of components. In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0123] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0124] In an exemplary embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0125] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0126] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0127] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0128] The technical features of the above embodiments may 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.

[0129] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for transient unbalanced high voltage ride-through of a direct-drive permanent magnet wind turbine generator set, characterized in that: include: The grid-side inverter of the direct-drive permanent magnet synchronous wind turbine generator is simulated as a virtual synchronous generator, and a virtual synchronous generator model of the inverter is constructed; Based on the virtual synchronous generator model of the inverter, construct an active loop control structure and a reactive loop control structure; Determining a virtual synchronous generator reference voltage based on the active loop control structure and the reactive loop control structure; Based on the virtual synchronous generator reference voltage, an unbalance analysis is performed on the direct-drive permanent magnet synchronous generator set at the grid connection point using the instantaneous symmetrical component method and Clarke coordinate change to obtain the positive and negative sequence components of the current and the positive and negative sequence components of the voltage; Determine the complex power based on the positive and negative sequence components of the current and the positive and negative sequence components of the voltage; the complex power is used to determine the influence of different power components on the power oscillation of the grid-side inverter under uneven voltage; Based on the influence of different power components on the power oscillation of the grid-side inverter under uneven voltage, a positive and negative sequence voltage-current dual closed-loop control strategy is constructed; The current inner loop in the positive and negative sequence voltage-current dual closed-loop control strategy is optimized into a sliding mode control, and a positive and negative sequence voltage-current dual closed-loop sliding mode control strategy is obtained; The positive and negative sequence voltage-current dual closed-loop sliding mode control strategy is executed based on the maximum torque control method.

2. The method for transient unbalanced high voltage ride through of a direct-drive permanent magnet wind turbine generator set according to claim 1, characterized in that: The virtual synchronous generator model of the inverter is: Where J is the moment of inertia, ω is the angular frequency of the virtual synchronous generator, t is time, T m is the mechanical torque of the virtual synchronous generator, T e is the electromagnetic torque of the virtual synchronous generator, T d is the damping torque of the virtual synchronous generator, D is the damping coefficient, ω0 is the angular frequency of the power grid, P e is the electromagnetic power, e a 、e b 、e c is the three-phase potential of the virtual synchronous generator, i a 、i b 、i c is the three-phase output current of the virtual synchronous generator.

3. The method for transient unbalanced high voltage ride through of a direct-drive permanent magnet wind turbine generator set according to claim 2, characterized in that: The active loop control structure is: Among them, P ref is the active power reference value; The reactive loop control structure is: Among them, Q ref is the reactive power reference value, Q e is the output reactive power, K is the integral coefficient, E is the virtual potential, e n is the rated voltage of the machine end.

4. The method for transient unbalanced high voltage ride through of a direct-drive permanent magnet wind turbine generator set according to claim 3 is characterized in that: The virtual synchronous generator reference voltage is: Among them, e ref is the reference voltage of the virtual synchronous generator, and θ is the voltage phase angle of the active loop output.

5. The method for transient unbalanced high voltage ride through of a direct-drive permanent magnet wind turbine generator set according to claim 4, characterized in that: The complex power is: S = P g +jQ g ; Where S is the complex power, P g is the active power, Q g is the reactive power.

6. The method for transient unbalanced high voltage ride through of a direct-drive permanent magnet wind turbine generator set according to claim 5, characterized in that: The active power includes the average value of the active power P0, the second harmonic sinusoidal component of the active power P s2 And the active power second harmonic cosine component P c2 ; Reactive power includes the average value of reactive power Q0, the second harmonic sinusoidal component of reactive power Q s2 And the reactive power second harmonic cosine component Q c2 ; The average value P0 of the active power, the second harmonic sinusoidal component P s2 , the active power second harmonic cosine component P c2 The reactive power includes the average value of the reactive power Q0, the second harmonic sinusoidal component of the reactive power Q s2 and the reactive power second harmonic cosine component Q c2 Both are controlled by the positive and negative sequence components of the current and the positive and negative sequence components of the voltage.

7. The method for transient unbalanced high voltage ride through of a direct-drive permanent magnet wind turbine generator set according to claim 6, characterized in that: The positive and negative sequence voltage-current dual closed-loop control strategy includes: a current command value under normal operation of the power grid and a negative sequence current command value under unbalanced high voltage state of the power grid; The current command value under the normal operation state of the power grid is: in, and are all current command values ​​under normal grid operation, R is the equivalent resistance of the power device on the grid-side inverter, L is the filter inductance on the grid-side inverter, and are the reference voltage command values ​​calculated by the virtual synchronous generator. ,and All are positive sequence components of voltage; The negative sequence current command value of the power grid under the unbalanced high voltage state is: in, and , are all negative sequence components of voltage.

8. The method for transient unbalanced high voltage ride through of a direct-drive permanent magnet wind turbine generator set according to claim 7, characterized in that: The sliding mode control comprises: Among them, S1 is the linear sliding surface, C1, C2, C3 and C4 are all constants, sgn is the sign function, and is the negative sequence current differential, and is the negative sequence current deviation in the dq coordinate system, and is the negative sequence current in the dq coordinate system, and is the negative sequence current command value in the dq coordinate system.

9. The method for transient unbalanced high voltage ride through of a direct-drive permanent magnet wind turbine generator set according to claim 8, characterized in that: The maximum torque control method is: Among them, u sd , is the voltage component of the generator in the d-axis direction, R s is the stator resistance, u sq , is the voltage component of the generator in the q-axis direction, i sd , is the current component of the generator in the d-axis direction, i sq is the current component of the generator in the q-axis direction, L sd , is the inductance component of the generator in the d-axis direction, L sq is the inductance component of the generator in the q-axis direction, ω s , is the synchronous angular velocity of the permanent magnet motor, ψ f It is the synchronous rotor flux of permanent magnet motor.

10. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for transient unbalanced high voltage ride-through of a direct-drive permanent magnet wind turbine generator set as described in any one of claims 1 to 9.

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