Wind power converter control method and device for coping with unbalanced grid voltage

Abstract

The present application discloses a control method and device for a wind power converter to cope with grid voltage imbalance. The device includes a DC voltage controller that obtains a grid-side active current command, an active current additional command, and a reactive current additional command; an additional current command generator that generates a machine-side active current additional command and a machine-side reactive current additional command; a machine-side current controller that generates a machine-side wave generation voltage action quantity; a grid-side current controller that generates a grid-side wave generation voltage action quantity; a machine-side modulator that obtains drive signals required for controlling the machine-side converter; and a grid-side modulator that obtains drive signals required for controlling the grid-side converter. The present application adjusts the double fundamental frequency component in the DC bus voltage through the DC voltage controller and superimposes the regulator output quantity on its machine-side current command, and can achieve the control objectives of sinusoidal balanced current output on the grid side of the converter and no fluctuation of the DC bus voltage under the condition of grid voltage imbalance.

Description

Technical Field

[0001] This application relates to the technical field of converters, and particularly to a control method and device for a wind power converter to cope with unbalanced grid voltage. Background Art

[0002] Developing new energy has become a global consensus to address the increasingly severe energy crisis, and the utilization of new energy is mainly achieved through power generation. As one of the main forces in new energy power generation, the grid-side operating performance of a wind power converter not only affects the quality of the generated electricity but also the stability of the power system.

[0003] However, when a converter is connected to the grid, it often faces the problem of unbalanced grid voltage. When facing unbalanced grid voltage, traditional control strategies designed based on the premise of balanced grid voltage are prone to the following problems: 1) The grid-side output power has an oscillation component with a double fundamental frequency; 2) The grid-side output current is distorted and unbalanced. Among them, the oscillation of the output power will cause the DC voltage to fluctuate at double frequency, increasing the voltage stress and loss of the DC-side capacitor; the unbalanced output current may cause the output current of the converter not to meet the requirements of the grid connection guidelines and may exacerbate the unbalance of the grid voltage at the node; the distortion of the output current will further reduce the quality of the transmitted electric energy.

[0004] To address the many problems existing in traditional control strategies, the industry has conducted a lot of research and proposed many improvement strategies. These strategies for optimizing the grid-side operating performance only consider the grid side. When the grid voltage is unbalanced, if only the grid side of the wind power converter is considered, the three goals of balanced output current, sinusoidal output current, and constant output power cannot be satisfied simultaneously, and only a compromise can be made [Literature 1 "Guo Xiaoqiang, Zhang Xue, Lu Zhigang, etc. Power / Current Quality Coordination Control Strategy for Photovoltaic Grid-Connected Inverters Under Unbalanced Grid Voltage [J]. Proceedings of the CSEE, 2014, 34(3): 346-353."]. Considering the requirements of power quality, it is often required that the grid-side output current of the converter be sinusoidal. Under this premise, only one of the goals of balanced output current and constant output power can be selected. Guided by this idea, generally, when the grid voltage unbalance degree is relatively low and the output power of the converter is not large, the control goal is set to constant grid-side output power of the converter; when the grid voltage unbalance degree is relatively high and the output power of the converter is large enough, to avoid overcurrent of the converter, the grid-side control goal is switched to balanced output current.

[0005] Whether the control goal is to keep the output power constant or balance the output current, ultimately, it is necessary to implement it by optimizing the output current command of the converter [Literature 2 "Pedro Rodriguez, Adrian V. Timbus, Remus Teodorescu, et al. Flexible active power control of distributed power generation systems during grid faults[J]. IEEE Transactions on Industrial Electronics, 2006, 21(3):1530-1540.", Literature 3 "Bo Yin, Ramesh Oruganti, Sanjib Kumar Panda, et al. An Output-Power-Control Strategy for a Three-Phase PWM Rectifier Under Unbalanced Supply Conditions[J]. IEEE Transactions on Industrial Electronics, 2006, 21(3):2140-2150."]. The optimized current command often needs to be calculated according to a specific formula [Literature 3 "Bo Yin, Ramesh Oruganti, Sanjib Kumar Panda, et al. An Output-Power-Control Strategy for a Three-Phase PWM Rectifier Under Unbalanced Supply Conditions[J]. IEEE Transactions on Industrial Electronics, 2006, 21(3):2140-2150.", Literature 4 "Yongsug Suh, Thomas A. Lipo. Control Scheme in Hybrid Synchronous Stationary Frame for PWM AC / DC Converter Under Generalized Unbalanced Operating Conditions[J]. IEEE Transactions on Industrial Applications, 2006, 42(3):825-835."].However, on the one hand, the division operation used in the calculation of the current command consumes a large amount of interrupt resources of the controller chip, and the voltage sequence component used to calculate the current command often needs to be filtered and extracted, resulting in a contradiction between the dynamic response and accuracy of the current command; on the other hand, whether the current command target can be achieved largely depends on the performance of the current controller. The traditional current control strategy based on PI regulation in a single rotating coordinate system is difficult to achieve precise control of negative sequence current.To achieve precise control of negative-sequence current, current control strategies based on positive- and negative-sequence double synchronous rotating coordinate systems [Literature 5 "Hong-seok Song, Kwanghee Nam. Dual current control for PWM converter under unbalanced input voltage conditions[J]. IEEE Transactions on Industrial Electronics, 1999, 46(5):953-959.", Literature 6 "Xiong Du, Shida Gu, Guoning Wang, et al. Simple current control method for three phase VSC under unbalanced grid condition[J]. IET Power Electron, 2018, 11(7):1161-1168."], an optimized current control strategy of paralleling a second-harmonic resonant regulator to the PI regulator in the traditional single rotating coordinate system [Literature 7 "Etxeberria-Otidui I, Viscarret U, Caballero M, et al. New optimized PWM VSC control structures and strategies under unbalanced voltage transients[J]. IEEE Transactions on Industrial Electronics, 2007, 54(5):2902-2914."], and a current control strategy of converting current control to the two-phase stationary coordinate system [Literature 8 "Zixin Li, Yaohua Li, Haibin Zhu, et al. Control of three-phase boost-type PWM Rectifier in stationary frame under unbalanced input voltage[J]. IEEE Transactions on Power Electronics, 2010, 25(10):2521-2530."] have been proposed successively and optimized to varying degrees.

[0006] By connecting a resonant regulator with a doubled center frequency in parallel to the DC voltage PI regulator, the doubled frequency pulsation of the DC bus voltage caused by grid voltage imbalance can also be suppressed [Reference 9 "Guo Xiaoqiang, Li Jian, Zhang Xue, et al. DC bus constant voltage control strategy without phase-locked loop for three-phase PWM rectifier under unbalanced grid voltage distortion [J]. Proceedings of the CSEE, 2015, 35(8): 2002-2008."]. Although this method can avoid the problems existing in the aforementioned current command calculation and can be implemented without relying on a high-performance current controller, it will cause a mismatch between the active negative sequence current and the reactive negative sequence current, resulting in grid-side output current distortion of the wind power converter. Summary of the Invention

[0007] The present application aims to provide a wind power converter control method and device for coping with grid voltage imbalance, so as to solve the problem that when the grid voltage is unbalanced, the existing wind power converter cannot balance the grid-side output current, suppress the DC bus voltage twice the fundamental frequency pulsation and maintain the grid-side output current sinusoidal.

[0008] In one aspect, the present application provides a control device for a grid-connected converter for grid voltage imbalance, wherein the wind power converter includes a generator-side converter and a grid-side converter; the device includes a grid-side phase-locked loop and a generator-side directional module, and further includes:

[0009] a DC voltage controller configured to obtain a grid-side active current instruction, an active current additional instruction, and a reactive current additional instruction according to a DC bus voltage instruction and a DC bus voltage detection value;

[0010] an additional current instruction generator, configured to generate a generator-side active current additional instruction and a generator-side reactive current additional instruction according to the active current additional instruction, the reactive current additional instruction, the grid-side phase-locked loop output angle, and the generator-side directional module output angle;

[0011] The machine-side current controller is configured to generate a machine-side wave voltage action according to a final machine-side active current command, a final machine-side reactive current command, a machine-side voltage, a machine-side current, and an output angle of a machine-side directional module; wherein the final machine-side active current command is the sum of the machine-side active current additional command and the machine-side basic active current command, and the final machine-side reactive current command is the sum of the machine-side reactive current additional command and the machine-side basic reactive current command;

[0012] A grid-side current controller is configured to generate a grid-side wave voltage action according to the grid-side active current command, the grid-side reactive current command, the grid-side voltage, the grid-side current, and the grid-side phase-locked loop output angle;

[0013] The machine-side modulator modulates the action quantity of the machine-side wave generation voltage to obtain the drive signal required for controlling the machine-side converter;

[0014] The grid-side modulator modulates the action quantity of the grid-side wave generation voltage to obtain the drive signal required for controlling the grid-side converter.

[0015] On the other hand, the present application provides a control method for a grid-connected converter for grid voltage imbalance. The method includes:

[0016] According to the DC bus voltage command and the DC bus voltage detection value, obtain the grid-side active current command, the active current additional command, and the reactive current additional command;

[0017] According to the active current additional command, the reactive current additional command, the angle output by the grid-side phase-locked loop, and the angle output by the machine-side orientation module, generate the machine-side active current additional command and the machine-side reactive current additional command;

[0018] According to the machine-side final active current command, the machine-side final reactive current command, the machine-side voltage, the machine-side current, and the angle output by the machine-side orientation module, generate the action quantity of the machine-side wave generation voltage; wherein, the machine-side final active current command is the sum of the machine-side active current additional command and the machine-side basic active current command, and the machine-side final reactive current command is the sum of the machine-side reactive current additional command and the machine-side basic reactive current command;

[0019] According to the grid-side active current command, the grid-side reactive current command, the grid-side voltage, the grid-side current, and the angle output by the grid-side phase-locked loop, generate the action quantity of the grid-side wave generation voltage;

[0020] Modulate the action quantity of the machine-side wave generation voltage to obtain the drive signal required for controlling the machine-side converter;

[0021] Modulate the action quantity of the grid-side wave generation voltage to obtain the drive signal required for controlling the grid-side converter.

[0022] The wind power converter control method and device for coping with grid voltage imbalance provided by the embodiments of the present application adjust the double fundamental frequency component in the DC bus voltage through a DC voltage controller and superimpose the output quantity of the regulator on the machine-side current command; solve the problem of incompatibility between the balance of the grid-side output current, the sinusoidal grid-side output current, and the elimination of the double fundamental frequency pulsation of the DC bus voltage under the condition of grid voltage imbalance, and can achieve the control objectives of sinusoidal balanced current output on the grid side of the converter and no fluctuation of the DC bus voltage under the condition of grid voltage imbalance. Description of the Drawings

[0023] Figure 1It is a control block diagram of a wind power converter for coping with grid voltage imbalance provided by an embodiment of the present application;

[0024] Figure 2 It is a schematic diagram of the principle of a grid-side PLL provided by an embodiment of the present application;

[0025] Figure 3 It is a schematic diagram of the principle of a DC voltage controller provided by an embodiment of the present application;

[0026] Figure 4 It is a schematic diagram of the principle of a current controller provided by an embodiment of the present application;

[0027] Figure 5 It is a schematic diagram of the simulation results of the existing one with the goal of output current balance and sine;

[0028] Figure 6 It is a schematic diagram of the simulation results of the existing one with the goals of suppressing the double-frequency pulsation of the DC bus voltage and output current sine;

[0029] Figure 7 It is a schematic diagram of the simulation results of the existing one with the goals of suppressing the double-frequency pulsation of the DC bus voltage and output current balance;

[0030] Figure 8 It is a schematic diagram of the simulation results of the single-phase grid drop of an embodiment of the present application;

[0031] Figure 9 It is a schematic diagram of a control method of a wind power converter for coping with grid voltage imbalance provided by an embodiment of the present application.

[0032] The realization, functional characteristics and advantages of the purpose of the present application will be further described with reference to the embodiments and the accompanying drawings. Specific embodiments

[0033] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0034] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present application. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0035] Variables involved in the embodiments of this application and their definitions:

[0036] u gabc : Grid-side voltage

[0037] i gabc : Grid-side current

[0038] L g : Equivalent leakage inductance of the power grid

[0039] L gf : Grid-side filter inductor

[0040] C f : Grid-side filter capacitor

[0041] θ g : Output phase of the grid-side phase-locked loop

[0042] u mabc : Machine-side voltage, which is also the stator voltage

[0043] i mabc : Machine-side current

[0044] L m : Machine-side filter inductor

[0045] θ s : Machine-side stator flux linkage angle

[0046] i kref_x 、i kref_y : x and y axis components of the grid-side (k = g) / machine-side (k = m) current action

[0047] i kx 、i ky : x and y axis components of the grid-side (k = g) / machine-side (k = m) feedback current

[0048] G N : Notch filter with a center frequency of twice the fundamental frequency

[0049] G R : Resonant regulator with a center frequency of twice the fundamental frequency

[0050] G QSG : Quadrature signal generator

[0051] e kref_x 、e kref_y : x and y axis components of the grid-side (k = g) / machine-side (k = m) wave voltage action

[0052] e kref_α 、e kre f _β : α and β axis components of the grid-side (k = g) / machine-side (k = m) wave voltage action

[0053] Figure 1 This is the control block diagram of a wind power converter for dealing with grid voltage imbalance provided by an embodiment of this application.

[0054] As Figure 1 shown, the control of the wind power converter for dealing with grid voltage imbalance is realized through a grid-side PLL (Phase Locked Loop), a DC voltage controller, an additional current command generator, a grid-side current controller, a machine-side current controller, a grid-side modulator, and a machine-side modulator.

[0055] Figure 2 This is the schematic diagram of the principle of the grid-side PLL provided by an embodiment of this application.

[0056] As Figure 2 shown, the input of the grid-side PLL (Phase Locked Loop) is the grid-side voltage u gabc of the converter. After coordinate transformation and PI regulation, the phase θ g of the positive sequence voltage of the grid is output.

[0057] Figure 3 This is the schematic diagram of the principle of the DC voltage controller provided by an embodiment of this application.

[0058] As Figure 3 shown, the inputs of the DC voltage controller are the DC bus voltage command U dc_ref , the detected value u dc of the DC bus voltage. The outputs are the grid-side active current command i gref_d , the additional active current command i ref_Auxp , and the additional reactive current command i ref_Auxq .

[0059] The DC voltage controller consists of a conventional DC voltage controller and a double-frequency grid fundamental pulsation suppressor. Among them, the conventional DC voltage controller uses a PI regulator to adjust the error between the DC bus voltage command and the detected value of the DC bus voltage to obtain the initial value of the grid-side active current command; the double-frequency grid fundamental pulsation suppressor uses a resonant regulator with a center frequency of twice the fundamental frequency to adjust the error between the DC bus voltage command and the detected value of the DC bus voltage to obtain the additional active current command required to suppress the double-frequency pulsation of the DC bus voltage.

[0060] Among them, the grid-side active current command i gref_d can be expressed as:

[0061]

[0062] In the formula, K p_VR and K i_VRThey are the proportional and integral coefficients of the DC voltage PI regulator, respectively. G N represents a notch filter with a center frequency of twice the fundamental frequency, which is used to filter out the component of twice the fundamental frequency in the output of the DC voltage PI regulator. The transfer function of its input-to-output characteristic can be expressed as:

[0063]

[0064] where ω n is the angular frequency corresponding to the center frequency of the notch filter, which is the angular frequency corresponding to twice the grid fundamental frequency in this embodiment; ω cn is the bandwidth coefficient of the notch filter, which takes values between 0 and 1.

[0065] The active current additional command can be expressed as:

[0066] i ref_Auxp = G R (U dc_ref - u dc ) (3)

[0067] In the formula, G R is a controller with high gain at twice the grid fundamental frequency.

[0068] In this embodiment, G R is set as a resonant regulator with a center frequency of twice the grid fundamental frequency. The transfer function of its output-to-input characteristic can be expressed as:

[0069]

[0070] where ω r is the angular frequency corresponding to the center frequency of the resonant regulator, which is the angular frequency corresponding to twice the grid fundamental frequency in this embodiment; ω cr is the bandwidth coefficient of the resonant regulator, which takes values between 0 and 1; K r is the gain of the resonant regulator.

[0071] Please refer to Figure 3 again. The implementation of DC voltage control can be divided into four steps.

[0072] First, use the PI regulator to adjust the error between U dc_ref and u dc to obtain the initial value i refp of the grid-side active current command; at the same time, use G R to adjust the component of twice the grid fundamental frequency in the DC voltage to obtain the active current additional command i ref_Auxp .

[0073] Second, use G NFilter the initial value of the grid-side active current command to obtain the grid-side active current command \(i\). gref_d ; At the same time, input the active current additional command into the quadrature signal generator \(G\). QSG to obtain the reactive current additional command \(i\). ref_Auxq . The transfer function of the input-to-output characteristic of the quadrature signal generator is:

[0074]

[0075] In the formula, \(K\). qsg is the gain of the quadrature signal generator, and \(\omega\). qsg is the angular frequency corresponding to the center frequency of the quadrature signal generator, which is the angular frequency corresponding to twice the grid fundamental frequency in this example.

[0076] Additional current command generator, according to the active current additional command \(i\). ref_Auxp and the reactive current additional command \(i\). ref_Auxq , combined with the output angle \(\theta\) of the grid-side phase-locked loop PLL g and the output angle \(\theta\) of the machine-side orientation module r , generate the machine-side active current additional command \(i\). mref_Auxq and the machine-side reactive current additional command \(i\). mref_Auxd .

[0077] Specifically, please refer to Figure 1 shown. The machine side takes the permanent magnet synchronous machine as the controlled object and adopts stator flux-oriented vector control. The implementation principle of the corresponding additional current command generator is:

[0078]

[0079] In the formula, \(\theta\). g and \(\theta\). s are the grid-side phase-locked angle and the stator flux angle respectively.

[0080] Figure 4 is the schematic diagram of the principle of the current controller provided by the embodiment of the present application.

[0081] The implementation principles of the grid-side current controller and the machine-side current controller are the same, and both can be implemented in the manner shown by Figure 4 .

[0082] As Figure 4 shown, the inputs of the current controller include the active and reactive current commands \(i\). kref_d , \(i\). kref_q (\(k = g\) represents the grid side, \(k = m\) represents the machine side, the same below), the \(k\)-side current \(i\). kabc , the voltage \(u\). kabc , the angle \(\theta\). k , and the outputs are the \(x\) and \(y\) axis components \(e\) of the wave generation voltage action quantity. kref_x, e kref_y . For the grid side of the converter, its active current command is the output i of the DC voltage conventional controller gref_d , and the grid side reactive current command i gref_q is set by the user according to the control requirements; for the machine side of the converter, its final active current command on the machine side consists of the basic active current command i mref_q0 output by the power outer loop and the additional active current command i mref_Auxq on the machine side. The final reactive current command on the machine side consists of the basic reactive current command i mref_d0 output by the machine side voltage outer loop and the additional reactive current command i mref_Auxd on the machine side.

[0083] The function of the current controller is implemented as follows:

[0084] First, in combination with the angle θ k , the current commands i kref_d , i kref_q are transformed to the target coordinate system xy coordinate system by using the current command coordinate transformation, and their x and y axis components i kref_x , i kref_y are obtained; at the same time, the current i kabc and the voltage u kabc are respectively transformed to the target coordinate system xy coordinate system by using the control coordinate transformation, and their x and y axis components i kx , i ky and u kx , u ky

[0085] When the target coordinate system is the dq synchronous rotating coordinate system, the current command coordinate transformation formula is:

[0086]

[0087] The current control coordinate transformation formula is:

[0088]

[0089] When the target coordinate system is the αβ stationary coordinate system, the current command coordinate transformation formula is:

[0090]

[0091] The current control coordinate transformation formula is:

[0092]

[0093] Second, the differences between the current commands on the x and y axes and the feedback are respectively sent to their respective current regulators G CRk(where k = g represents the grid side and k = m represents the machine side, the same hereinafter), and then the outputs of the x- and y-axis current regulators G CRk are respectively superimposed on the x- and y-axis components of the voltage to obtain the x- and y-axis components e kref_x 、e kref_y of the wave generation voltage action quantity.

[0094] Then, through the wave generation voltage coordinate transformation module, the x- and y-axis components e kref_x 、e kref_y of the wave generation voltage action quantity are transformed into the αβ coordinate system to obtain the α- and β-axis components e kref_α 、e kref_β of the final voltage action quantity.

[0095] When the target coordinate system of the current controller is the dq coordinate system, the transformation formula of the wave generation voltage coordinate transformation module is:

[0096]

[0097] When the target coordinate system of the current controller is the αβ coordinate system, the transformation formula of the wave generation voltage coordinate transformation module is:

[0098]

[0099] Finally, the grid side modulator and the machine side modulator perform PWM modulation on the obtained wave generation voltage action quantities on the machine side and the grid side, for example, using the three-phase space vector modulation method, to obtain the drive signals required for the machine side and grid side converters of the wind power converter.

[0100] Figure 5 is a schematic diagram of the simulation results of the existing one with the goal of output current balance and sinusoid. Figure 6 is a schematic diagram of the simulation results of the existing one with the goal of suppressing the double-frequency pulsation of the DC bus voltage and output current sinusoid. Figure 7 is a schematic diagram of the simulation results of the existing one with the goal of suppressing the double-frequency pulsation of the DC bus voltage and output current balance. Figure 8 is a schematic diagram of the simulation results of the grid single-phase dip provided by the embodiment of the present application.

[0101] It can be seen from the above schematic diagram of the simulation results that the control of the wind power converter for coping with grid voltage imbalance provided by the embodiment of the present application can achieve the control goals of sinusoidal balanced current output on the grid side of the converter and no fluctuation of the DC bus voltage under the condition of grid voltage imbalance, and solves the problem of incompatibility of output current balance on the grid side of the wind power converter, sinusoidal output current on the grid side, and suppression of the double-frequency fundamental pulsation of the DC bus voltage under the condition of grid voltage imbalance.

[0102] Figure 9Schematic diagram of a wind power converter control method for coping with grid voltage imbalance provided by an embodiment of the present application.

[0103] As Figure 9 shown, the method includes:

[0104] S11. Obtain a grid-side active current command, an active current additional command, and a reactive current additional command according to a DC bus voltage command and a DC bus voltage detection value;

[0105] S12. Generate a machine-side active current additional command and a machine-side reactive current additional command according to the active current additional command, the reactive current additional command, the angle output by the grid-side phase-locked loop, and the angle output by the machine-side orientation module;

[0106] S13. Generate a machine-side wave generation voltage action quantity according to the machine-side final active current command, the machine-side final reactive current command, the machine-side voltage, the machine-side current, and the angle output by the machine-side orientation module; wherein, the machine-side final active current command is the sum of the machine-side active current additional command and the machine-side basic active current command, and the machine-side final reactive current command is the sum of the machine-side reactive current additional command and the machine-side basic reactive current command;

[0107] S14. Generate a grid-side wave generation voltage action quantity according to the grid-side active current command, the grid-side reactive current command, the grid-side voltage, the grid-side current, and the angle output by the grid-side phase-locked loop;

[0108] S15. Modulate the machine-side wave generation voltage action quantity to obtain a drive signal required for controlling the machine-side converter;

[0109] S16. Modulate the grid-side wave generation voltage action quantity to obtain a drive signal required for controlling the grid-side converter.

[0110] It should be noted that there is no sequence between the above steps S13 and S14, and there is no sequence between the above steps S15 and S16.

[0111] In one example, a controller with high gain at twice the grid fundamental frequency is used to adjust the error between the DC bus voltage command and the DC bus voltage detection value to obtain the active current additional command; and then the active current additional command is adjusted through a quadrature signal generator to obtain the reactive current additional command.

[0112] In one example, the controller with high gain at twice the grid fundamental frequency includes a resonant regulator or a repetitive controller with a center frequency of twice the grid fundamental frequency.

[0113] In one example, the output of the quadrature signal generator has the same amplitude as the specified frequency component in the input signal and a phase difference of 90 degrees.

[0114] In one example, the grid-side phase-locked loop outputs the phase of the positive-sequence voltage of the power grid after coordinate transformation and PI regulation of the grid-side voltage.

[0115] In one example, the angle output by the machine-side orientation module is obtained by detecting with a code disk or by observing the motor voltage.

[0116] In one example, both the grid-side current controller and the machine-side current controller are configured to execute in a synchronous rotating coordinate system or a two-phase stationary coordinate system.

[0117] In one example, according to the angle output by the machine-side orientation module, using current command coordinate transformation, the machine-side final active current command, the machine-side final reactive current command, the machine-side current, and the machine-side voltage are transformed to a target coordinate system to obtain the machine-side current command component, the machine-side feedback current component, and the machine-side feedback voltage component in the target coordinate system;

[0118] The difference between the machine-side current command component and the machine-side feedback current component in the target coordinate system is adjusted and then superimposed on the machine-side feedback voltage component to obtain the machine-side wave generation voltage action quantity.

[0119] In one example, according to the angle output by the grid-side phase-locked loop, using current command coordinate transformation, the grid-side active current command, the grid-side reactive current command, the grid-side current, and the grid-side voltage are transformed to a target coordinate system to obtain the grid-side current command component, the grid-side feedback current component, and the grid-side feedback voltage component in the target coordinate system;

[0120] The difference between the grid-side current command component and the grid-side feedback current component in the target coordinate system is adjusted and then superimposed on the grid-side feedback voltage component to obtain the grid-side wave generation voltage action quantity.

[0121] The preferred embodiments of the present application have been described above with reference to the accompanying drawings. However, this does not limit the scope of the rights of the present application. Any modifications, equivalent replacements, and improvements made by those skilled in the art without departing from the scope and essence of the present application shall fall within the scope of the rights of the present application.

Claims

1. A wind power converter control device for coping with grid voltage imbalance, wherein the wind power converter comprises a generator-side converter and a grid-side converter; the device comprises a grid-side phase-locked loop and a generator-side directional module, and is characterized in that: The device further comprises: a DC voltage controller configured to obtain a grid-side active current instruction, an active current additional instruction, and a reactive current additional instruction according to a DC bus voltage instruction and a DC bus voltage detection value; an additional current instruction generator, configured to generate a generator-side active current additional instruction and a generator-side reactive current additional instruction according to the active current additional instruction, the reactive current additional instruction, the grid-side phase-locked loop output angle, and the generator-side directional module output angle; The machine-side current controller is configured to generate a machine-side wave voltage action according to a final machine-side active current command, a final machine-side reactive current command, a machine-side voltage, a machine-side current, and an output angle of a machine-side directional module; wherein the final machine-side active current command is the sum of the machine-side active current additional command and the machine-side basic active current command, and the final machine-side reactive current command is the sum of the machine-side reactive current additional command and the machine-side basic reactive current command; A grid-side current controller is configured to generate a grid-side wave voltage action according to the grid-side active current command, the grid-side reactive current command, the grid-side voltage, the grid-side current, and the grid-side phase-locked loop output angle; A generator-side modulator modulates the generator-side wave voltage action to obtain a driving signal required for controlling the generator-side converter; The grid-side modulator modulates the grid-side wave voltage action to obtain a driving signal required for controlling the grid-side converter.

2. The device according to claim 1, characterized in that The DC voltage controller includes a double grid fundamental frequency ripple suppressor; The double grid fundamental frequency pulsation suppressor is configured to use a controller with high gain at double the grid fundamental frequency to adjust the error between the DC bus voltage command and the DC bus voltage detection value to obtain the active current additional command; and then adjust the active current additional command through an orthogonal signal generator to obtain the reactive current additional command.

3. The device according to claim 2, characterized in that The controller having a high gain at twice the grid fundamental frequency comprises a resonant regulator or a repetitive controller having a center frequency of twice the grid fundamental frequency.

4. The device according to claim 2, characterized in that The output of the orthogonal signal generator has the same amplitude as the specified frequency component in the input signal and a phase difference of 90 degrees.

5. The device according to claim 1, characterized in that The grid-side phase-locked loop outputs the phase of the grid positive sequence voltage after coordinate transformation and PI regulation of the grid-side voltage.

6. The device according to claim 1, characterized in that The angle output by the machine-side orientation module is obtained by detecting a code disk or observing the motor voltage.

7. The device according to claim 1, characterized in that The grid-side current controller and the generator-side current controller are both configured to be executed in a synchronous rotating coordinate system or a two-phase stationary coordinate system.

8. The device according to claim 1, characterized in that The generator-side current controller is configured as follows: According to the output angle of the machine-side directional module, the machine-side final active current command, the machine-side final reactive current command, the machine-side current, and the machine-side voltage are converted into the target coordinate system by using the current command coordinate transformation to obtain the machine-side current command component, the machine-side feedback current component, and the machine-side feedback voltage component in the target coordinate system; The difference between the generator-side current command component and the generator-side feedback current component in the target coordinate system is adjusted and then superimposed with the generator-side feedback voltage component to obtain the generator-side wave voltage action.

9. The device according to claim 1, characterized in that The grid-side current controller is configured as follows: According to the grid-side phase-locked loop output angle, the grid-side active current command, the grid-side reactive current command, the grid-side current, and the grid-side voltage are converted into a target coordinate system using current command coordinate transformation to obtain a grid-side current command component, a grid-side feedback current component, and a grid-side feedback voltage component in the target coordinate system; The difference between the grid-side current command component and the grid-side feedback current component in the target coordinate system is adjusted and then superimposed with the grid-side feedback voltage component to obtain the grid-side wave voltage action.

10. A wind power converter control method for coping with grid voltage imbalance, wherein the wind power converter comprises a generator-side converter and a grid-side converter; characterized in that: The method comprises: According to the DC bus voltage command and the DC bus voltage detection value, the grid-side active current command, the active current additional command and the reactive current additional command are obtained; Generate a machine-side active current additional instruction and a machine-side reactive current additional instruction according to the active current additional instruction, the reactive current additional instruction, the grid-side phase-locked loop output angle, and the machine-side directional module output angle; Generate the machine-side wave voltage action according to the machine-side final active current command, the machine-side final reactive current command, the machine-side voltage, the machine-side current, and the output angle of the machine-side directional module; wherein the machine-side final active current command is the sum of the machine-side active current additional command and the machine-side basic active current command, and the machine-side final reactive current command is the sum of the machine-side reactive current additional command and the machine-side basic reactive current command; Generate a grid-side wave voltage action according to the grid-side active current command, the grid-side reactive current command, the grid-side voltage, the grid-side current, and the grid-side phase-locked loop output angle; Modulating the generator-side wave voltage action to obtain a driving signal required for controlling the generator-side converter; The grid-side wave voltage action amount is modulated to obtain a driving signal required for controlling the grid-side converter.

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