Control method and device of grid-side converter, storage medium and electronic device

Abstract

The invention discloses a grid-side converter control method and device, a storage medium and an electronic device, and the method comprises the steps that a grid-side converter belongs to a doubly-fed wind turbine generator, the doubly-fed wind turbine generator further comprises a machine-side converter, and the method comprises the steps: determining a target control circuit set for the grid-side converter, the target control circuit at least comprises an equivalent resistance circuit and an initial control circuit, the equivalent resistance circuit is used for carrying out additional damping control, and the initial control circuit represents a circuit set according to an initial control strategy; obtaining a generator terminal voltage dq component of the generator terminal voltage under a control coordinate system of the grid-side converter after the phase locking link, wherein the generator terminal voltage is output by the generator-side converter of the doubly-fed wind turbine generator; inputting the terminal voltage dq component into a target control circuit to obtain a target current output by the target control circuit; and controlling the grid-side converter based on a current instruction generated by the target current. By adopting the technical scheme, the technical problem that the subsynchronous oscillation during grid connection of the doubly-fed wind turbine generator cannot be effectively controlled is solved.

Description

Technical Field

[0001] The present application relates to the technical field of renewable energy power generation, and in particular to a control method and device for a grid-side converter, a storage medium, and an electronic device. Background Art

[0002] With the continuous increase in wind power installed capacity, the stability of wind power grid-connected systems has become increasingly complex, especially under the conditions of large-scale wind power access. The mutual coupling between regional cluster wind power and the power grid, and between wind power and adjacent power electronic drive equipment through the dynamic characteristics of the grid connection point voltage has greatly affected the stability. Due to the reverse distribution of wind power resources and loads and the base-based and large-scale characteristics of wind power construction, large-scale wind power is currently delivered through transmission technologies such as series capacitor compensation and HVDC (High Voltage Direct Current), which also increases the risk of subsynchronous oscillation of wind power grid connection.

[0003] Doubly-fed wind turbines are the mainstream type of wind turbines currently connected to the grid. In actual production and operation, the wind power sent by large-scale doubly-fed wind turbines through series compensation has subsynchronous oscillation problems. At present, the main reason for subsynchronous oscillation caused by wind power grid connection is the interaction between the wind power control system and the power grid. Specifically, the doubly-fed wind turbine and the transmission system work together to produce an oscillation mode. The wind turbine control system actively participates in this interaction and injects negative damping into the oscillation mode. In response to this, in the related technology, an additional damping control strategy based on FACTS (Flexible AC Transmission Systems) controller is proposed, such as the additional damping control using SVG (Static Var Generator) and UPFC (Unified Power Flow Controller), etc., and a method of designing an additional damping control strategy for doubly-fed wind turbines is also proposed to provide damping for subsynchronous oscillation modes.

[0004] However, current research focuses on designing control strategies related to the grid-connected characteristics of doubly-fed wind turbines in the machine-side converter, which only controls the slip power transmitted by the grid-side converter, and does not consider the dynamic impact of the grid-side converter of the doubly-fed wind turbine on the subsynchronous oscillation. This method of designing a control strategy for subsynchronous oscillation suppression that only considers the machine-side converter cannot effectively control the subsynchronous oscillation when the doubly-fed wind turbine is connected to the grid. Therefore, in the related art, there is a technical problem that the subsynchronous oscillation of the doubly-fed wind turbine cannot be effectively controlled when the doubly-fed wind turbine is connected to the grid.

[0005] With regard to the technical problem in the related art that the subsynchronous oscillation of the doubly-fed wind turbine generator set cannot be effectively controlled when it is connected to the grid, no effective solution has been proposed so far.

[0006] Therefore, it is necessary to improve the related technology to overcome the above-mentioned defects in the related technology. Summary of the invention

[0007] The embodiments of the present application provide a control method and device for a grid-side converter, a storage medium and an electronic device to at least solve the technical problem of being unable to effectively control the subsynchronous oscillation of a doubly-fed wind turbine when it is connected to the grid.

[0008] According to one aspect of an embodiment of the present application, a control method for a grid-side converter is provided, including: the grid-side converter belongs to a doubly-fed wind turbine group, the doubly-fed wind turbine group also includes a machine-side converter, including: determining a target control circuit set for the grid-side converter, the target control circuit at least includes an equivalent resistance circuit and an initial control circuit, the equivalent resistance circuit is used to perform additional damping control, and the initial control circuit represents a circuit set according to an initial control strategy; obtaining a machine-end voltage dq component in a control coordinate system of the grid-side converter after the machine-end voltage passes through a phase-locked link, the machine-end voltage is output by the machine-side converter of the doubly-fed wind turbine group; inputting the machine-end voltage dq component into the target control circuit to obtain a target current output by the target control circuit, the target current at least includes a first current for additional damping control output by the equivalent resistance circuit, and a second current output by the initial control circuit; and controlling the output current of the grid-side converter based on a current instruction generated by the target current.

[0009] In an exemplary embodiment, determining a target control circuit to be set for the grid-side converter includes: adding the equivalent resistance circuit to the initial control circuit to obtain the target control circuit, wherein the initial control circuit at least includes a DC voltage outer loop circuit and a current inner loop circuit, the equivalent resistance circuit and the DC voltage outer loop circuit are connected in parallel, and the target control circuit is used to provide a constant DC capacitor voltage value.

[0010] In an exemplary embodiment, the equivalent resistance circuit is used to provide an expected per-unit value of resistance, and the expected per-unit value has a value range of [0.2, 1].

[0011] In an exemplary embodiment, the method further includes: acquiring a target reactive power preset for the doubly-fed wind turbine generator set, and controlling the reactive power generated by the target control circuit to be consistent with a power value of the target reactive power.

[0012] In an exemplary embodiment, before controlling the output current of the grid-side converter based on the current command generated by the target current, the method further includes: performing a limiting operation on the first current to obtain a third current, wherein the per-unit value of the current limiting value of the third current belongs to a preset range; determining the target current based on the third current and the second current, and generating a current command according to the target current.

[0013] In an exemplary embodiment, generating a current command based on the target current includes: generating a first control command based on the second current, generating a second control command according to the third current, and generating the current command according to the first control command and the second control command.

[0014] According to another aspect of an embodiment of the present application, a control device for a grid-side converter is also provided, including: a determination module, used to determine a target control circuit set for the grid-side converter, the target control circuit at least including an equivalent resistance circuit and an initial control circuit, the equivalent resistance circuit being used for additional damping control, and the initial control circuit representing a circuit set according to an initial control strategy; an acquisition module, used to acquire a dq component of the machine-end voltage in the control coordinate system of the grid-side converter after the machine-end voltage passes through a phase-locked link, the machine-end voltage being output by the machine-side converter of a doubly-fed wind turbine generator set; an acquisition module, used to input the dq component of the machine-end voltage into the target control circuit to obtain a target current output by the target control circuit, the target current at least including a first current for additional damping control output by the equivalent resistance circuit, and a second current output by the initial control circuit; a control module, used to control the output current of the grid-side converter based on a current instruction generated by the target current.

[0015] According to another aspect of the embodiments of the present application, a computer-readable storage medium is provided, in which a computer program is stored, wherein the computer program is configured to execute the control method of the grid-side converter when running.

[0016] According to another aspect of the embodiments of the present application, there is also provided an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the control method of the grid-side converter through the computer program.

[0017] According to another aspect of the present application, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the steps in any one of the above method embodiments are implemented.

[0018] Through the present application, by determining a target control circuit set for the grid-side converter, the target control circuit at least includes an equivalent resistance circuit and an initial control circuit, the equivalent resistance circuit is used to perform additional damping control, and the initial control circuit represents a circuit set according to an initial control strategy; obtaining the dq component of the machine-end voltage in the control coordinate system of the grid-side converter after the machine-end voltage passes through a phase-locked link, the machine-end voltage is output by the machine-side converter of the doubly-fed wind turbine generator set; inputting the dq component of the machine-end voltage into the target control circuit to obtain a target current output by the target control circuit, the target current at least includes a first current for additional damping control output by the equivalent resistance circuit, and a second current output by the initial control circuit; and controlling the output current of the grid-side converter based on a current instruction generated by the target current. The present application solves the technical problem of not being able to effectively control the subsynchronous oscillation of the doubly fed wind turbine when it is connected to the grid by introducing an equivalent resistance circuit into the control circuit of the grid-side converter for additional damping control, improves the control efficiency of the subsynchronous oscillation of the doubly fed wind turbine when it is connected to the grid, effectively suppresses the subsynchronous oscillation of the doubly fed wind turbine when it is connected to the grid, and thereby improves the stability of the doubly fed wind turbine when it is connected to the grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0020] 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 or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0021] Figure 1 It is a hardware structure block diagram of a mobile terminal of a control method for a grid-side converter according to an embodiment of the present application;

[0022] Figure 2 is a flow chart of a control method of a grid-side converter according to an embodiment of the present application;

[0023] Figure 3 is a schematic diagram of a control circuit according to an embodiment of the present application (I);

[0024] Figure 4 is a schematic diagram of a control circuit according to an embodiment of the present application (II);

[0025] Figure 5 is a wiring diagram of a simulation example of a doubly-fed wind turbine generator set according to an embodiment of the present application;

[0026] Figure 6 is a simulation curve diagram of suppressing subsynchronous oscillation based on an equivalent resistance circuit according to an embodiment of the present application;

[0027] Figure 7 It is a structural block diagram of a control device of a grid-side converter according to an embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings 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 should fall within the scope of protection of this application.

[0029] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0030] The method embodiments provided in the embodiments of the present application can be executed in a mobile terminal, a computer terminal or a similar computing device. Taking running on a mobile terminal as an example, Figure 1 1 is a hardware structure block diagram of a mobile terminal of a method for controlling a grid-side converter according to an embodiment of the present application. Figure 1 As shown, the mobile terminal may include one or more ( Figure 1 Only one is shown in the figure) a processor 102 (the processor 102 may include but is not limited to a microprocessor or a processing device such as a programmable logic device (Field Programmable Gate Array, FPGA)) and a memory 104 for storing data, wherein the mobile terminal may also include a transmission device 106 and an input / output device 108 for communication functions. It can be understood by those skilled in the art that Figure 1 The structure shown is only for illustration and does not limit the structure of the mobile terminal. Figure 1 More or fewer components as shown, or with Figure 1 Different configurations are shown.

[0031] The memory 104 can be used to store computer programs, for example, software programs and modules of application software, such as the computer program corresponding to the control method of the grid-side converter in the embodiment of the present application. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, that is, to implement the above method. The memory 104 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 104 may further include a memory remotely arranged relative to the processor 102, and these remote memories may be connected to the mobile terminal via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0032] The transmission device 106 is used to receive or send data via a network. The specific example of the above network may include a wireless network provided by a communication provider of the mobile terminal. In one example, the transmission device 106 includes a network adapter (Network Interface Controller, referred to as NIC), which can be connected to other network devices through a base station so as to communicate with the Internet. In one example, the transmission device 106 can be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0033] In this embodiment, a control method for a grid-side converter is provided, wherein the grid-side converter belongs to a doubly-fed wind turbine set, and the doubly-fed wind turbine set also includes a machine-side converter. The doubly-fed wind turbine set is, for example, a doubly-fed induction generator (DFIG). A doubly-fed induction generator is a type of AC generator widely used in wind power generation. In a doubly-fed induction generator, the stator winding is directly connected to the grid, while the rotor winding is connected to the grid through a bidirectional converter (for example, a PWM converter). This design allows the generator to operate under variable speed (i.e., variable speed) conditions, and the output active power and reactive power can be independently controlled. When the rotor of the doubly-fed induction generator rotates at different speeds, the current in the rotor winding can be controlled by the converter, thereby controlling the electromagnetic torque and output power generated by the generator. This capability enables the doubly-fed induction generator to maintain the stability of the grid when the wind speed changes, and to efficiently utilize wind energy. The way the doubly-fed induction generator is connected to the grid also means that it can operate at the grid frequency, or at subsynchronous or supersynchronous frequencies, which increases its flexibility and efficiency in wind power generation. At the same time, since the converter capacity on the rotor side is usually smaller than the total capacity of the generator, this also reduces the cost of the system. In wind power generation, the doubly-fed induction generator can achieve variable speed constant frequency power output, improving the power quality and system stability of wind power generation.

[0034] In fact, since the oscillation frequency of the subsynchronous oscillation is close to the bandwidth of the DC voltage control loop of the grid-side converter, and the power transmitted by its output includes the subsynchronous oscillation power component existing in the rotor, the control response characteristics of the grid-side converter have a significant impact on the dynamic process of the subsynchronous oscillation. Moreover, considering that in actual operation, the capacity of the grid-side converter accounts for more than one-third of the rated capacity of the doubly fed unit, designing a control strategy for subsynchronous oscillation suppression in the grid-side converter not only has higher control flexibility and more direct control characteristics for the grid oscillation components, but also helps to reduce the complexity of the machine-side converter control strategy. Therefore, in response to the shortcomings of subsynchronous oscillations in the grid-connected DFIG doubly fed wind turbines, this application controls the subsynchronous oscillation of the doubly fed wind power grid-connected system based on the design concept of the equivalent resistance circuit of the grid-side converter, thereby improving the system's anti-interference ability and system stability. Figure 2 As shown, the specific implementation steps are as follows:

[0035] Step S202: determining a target control circuit set for the grid-side converter, the target control circuit comprising at least an equivalent resistance circuit and an initial control circuit, the equivalent resistance circuit being used for additional damping control, and the initial control circuit representing a circuit set according to an initial control strategy;

[0036] The above-mentioned initial control circuit can be understood as a circuit implemented using an existing control strategy of the relevant technology. In this control circuit, the power flowing to the wind power system is P. When the wind power system contains a subsynchronous oscillation component, the power Ps output by the machine-side converter and the power Pg output by the grid-side converter both inject subsynchronous oscillation power into the system. In the related art, the subsynchronous oscillation component contained in Ps is reduced by applying an additional damping control strategy in the machine-side converter. However, no matter how it is reduced, the power P injected into the system will still contain a certain subsynchronous oscillation component. Therefore, the present application introduces an equivalent resistor in the grid-side converter, which is equivalent to connecting a virtual bypass filter in parallel with the subsynchronous oscillation component at the machine-end node, thereby changing the power flow direction of the subsynchronous oscillation component in Pg, so that the subsynchronous oscillation component in Ps does not flow to the system, destroying the conditions for the interaction of subsynchronous oscillations between the control system of the doubly fed wind turbine set and the power grid, and obtaining a good subsynchronous oscillation damping effect.

[0037] In this step, by adding damping control to the grid-side converter, the damping characteristics of the system are enhanced, the anti-interference ability of the doubly-fed wind turbine during grid fluctuations is improved, and equipment damage caused by grid failures is effectively avoided, thereby improving the operating safety and reliability of the wind turbine.

[0038] Step S204: obtaining the dq component of the machine-side voltage in the control coordinate system of the grid-side converter after the machine-side voltage passes through the phase-locked link, wherein the machine-side voltage is output by the machine-side converter of the doubly-fed wind turbine generator set;

[0039] Among them, the phase locked loop (PLL) in the wind power system is mainly used to extract the rotation angle of the synchronous rotating reference coordinate system from the three-phase grid voltage, so as to convert the three-phase AC signal into a DC signal, or more specifically, to convert the voltage or current of the three-phase AC system into a fixed dq coordinate system, where the d-axis is in phase with the fundamental voltage vector of the grid, and the q-axis is orthogonal to the d-axis.

[0040] It should be noted that in the field of power electronics and motor control, the dq coordinate system is a coordinate system fixed to the rotating electric field, in which the d-axis (direct axis) is in phase with the rotating magnetic field or the grid fundamental voltage vector, while the q-axis (quadrature axis) is 90 degrees out of phase with the d-axis, i.e., orthogonal. The purpose of this coordinate system conversion is to simplify the control of the AC motor, so that the mathematical model of the motor in the rotating coordinate system is closer to the model of the DC motor, thereby simplifying the control algorithm.

[0041] The voltage dq component conversion process in the grid-side converter control coordinate system specifically includes the following steps:

[0042] 1. Signal sampling: First, collect three-phase voltage signals (Va, Vb, Vc) from the grid side of the wind turbine.

[0043] 2. Phase-locked loop: Then, a PLL is used to extract the phase and frequency of the grid voltage from the three-phase voltage signal. Through a feedback control mechanism, the PLL matches the phase and frequency of a local oscillator with the phase and frequency of the input grid voltage, generating a rotating coordinate system whose d-axis is in phase with the grid fundamental voltage and whose q-axis is 90 degrees out of phase with the d-axis.

[0044] 3. Clark transformation: Next, the three-phase voltage signal is converted into the voltage (Vα, Vβ) in the two-phase stationary coordinate system through Clark transformation. Clark transformation is a coordinate transformation that converts the three-phase stationary coordinate system into the two-phase stationary coordinate system and eliminates the negative sequence and zero sequence components of the three-phase system.

[0045] 4. Park transformation: Finally, the voltage signal in the two-phase stationary coordinate system is transformed into the rotating dq coordinate system through Park transformation. Park transformation is a coordinate transformation based on the rotating coordinate system, which transforms the signal of the two-phase stationary coordinate system into a DC signal in the dq coordinate system (i.e., the control coordinate system) that rotates synchronously with the fundamental voltage of the power grid. In this coordinate system, the d-axis voltage (Vd) reflects the in-phase component with the fundamental voltage of the power grid, while the q-axis voltage (Vq) reflects the orthogonal component with the fundamental voltage of the power grid.

[0046] Through the above process, the dq components of the machine-end voltage in the grid-side converter control coordinate system can be obtained, which enables the controller to better identify and process dynamic changes in the power grid, especially oscillations in the sub-synchronous frequency range, and provides an accurate reference signal for the subsequent virtual resistor additional damping control strategy.

[0047] Step S206: inputting the dq component of the machine-end voltage into the target control circuit to obtain a target current output by the target control circuit, wherein the target current at least includes a first current of the additional damping control output by the equivalent resistance circuit and a second current output by the initial control circuit;

[0048] Step S208: controlling the output current of the grid-side converter based on the current command generated by the target current.

[0049] Through the above steps, by determining the target control circuit set for the grid-side converter, the target control circuit at least includes an equivalent resistance circuit and an initial control circuit, the equivalent resistance circuit is used for additional damping control, and the initial control circuit represents a circuit set according to an initial control strategy; obtaining the dq component of the machine-end voltage in the control coordinate system of the grid-side converter after the machine-end voltage passes through a phase-locked link, the machine-end voltage is output by the machine-side converter of the doubly-fed wind turbine generator set; inputting the dq component of the machine-end voltage into the target control circuit to obtain a target current output by the target control circuit, the target current at least includes a first current for additional damping control output by the equivalent resistance circuit, and a second current output by the initial control circuit; and controlling the output current of the grid-side converter based on a current instruction generated by the target current. The present application solves the technical problem of not being able to effectively control the subsynchronous oscillation of the doubly fed wind turbine when it is connected to the grid by introducing an equivalent resistance circuit into the control circuit of the grid-side converter for additional damping control, improves the control efficiency of the subsynchronous oscillation of the doubly fed wind turbine when it is connected to the grid, effectively suppresses the subsynchronous oscillation of the doubly fed wind turbine when it is connected to the grid, and thereby improves the stability of the doubly fed wind turbine when it is connected to the grid.

[0050] In an exemplary embodiment, the implementation process of the target control circuit determined to be set for the grid-side converter includes: adding the equivalent resistance circuit to the initial control circuit to obtain the target control circuit, wherein the initial control circuit at least includes a DC voltage outer loop circuit and a current inner loop circuit, the equivalent resistance circuit and the DC voltage outer loop circuit are connected in parallel, and the target control circuit is used to provide a constant DC capacitor voltage value. The present application achieves stable control of the DC capacitor voltage by combining the equivalent resistance circuit with the initial control circuit, reduces capacitor voltage fluctuations, prevents current mutations from damaging the equipment, and ensures the normal operation of the system.

[0051] The inner current loop of the grid-side converter may be implemented by a proportional-integral controller, and the outer DC voltage control loop may be implemented by a droop control strategy.

[0052] In an exemplary embodiment, the equivalent resistance circuit is used to provide an expected per-unit value of resistance, and the expected per-unit value has a value range of [0.2, 1]. By setting the value range of the expected per-unit value, the control strategy of the grid-side converter under normal operation can be improved while the additional control effect is not interfered. In this embodiment, for example, the expected per-unit value is selected as 0.5 to achieve the optimal damping effect.

[0053] In an exemplary embodiment, further, a preset target reactive power for the doubly-fed wind turbine can be obtained, and the reactive power generated by the target control circuit can be controlled to be consistent with the power value of the target reactive power. This embodiment further optimizes the control strategy by setting reactive power, realizes accurate control of the DC capacitor voltage, improves the response speed and control accuracy of the system, improves the stable operation of the system, and improves the power quality of the wind turbine.

[0054] In an exemplary embodiment, before the current command generated based on the target current controls the output current of the grid-side converter, further, the first current may be limited to obtain a third current, wherein the per-unit value of the current limit value of the third current belongs to a preset range; the target current is determined based on the third current and the second current, and a current command is generated according to the target current. In this embodiment, the response speed and control accuracy of the system can be effectively improved through the limiting operation, providing technical support for the efficient operation of the wind turbine.

[0055] This embodiment can ensure that the control instruction is within a safe range by setting a preset range of per-unit values ​​of the current amplitude limit value. Optionally, the preset range of per-unit values ​​of the current amplitude limit value is set to [-0.5, 0.5], that is, i_max=0.5 and i_min=-0.5.

[0056] In an exemplary embodiment, generating a current instruction based on the target current specifically includes: generating a first control instruction based on the second current, generating a second control instruction according to the third current, and generating the current instruction according to the first control instruction and the second control instruction.

[0057] Obviously, the embodiments described above are only some embodiments of the present application, not all embodiments. In order to better understand the above method, the above process is described below in conjunction with the embodiments, but it is not intended to limit the technical solutions of the embodiments of the present application, specifically:

[0058] In an optional embodiment, a subsynchronous oscillation control strategy based on the equivalent resistance design of the DFIG grid-side converter is proposed, specifically referring to a control strategy of adding an equivalent resistance design in the grid-side converter of the doubly-fed wind turbine to realize additional subsynchronous oscillation damping. The control process of the grid-side converter can be better described by the following steps:

[0059] Step 1: Design a grid-side converter control strategy under normal operation (corresponding to the above initial control circuit). In the grid-side converter control strategy under normal operation, there are Figure 3The current inner loop circuit and DC voltage control outer loop circuit shown in the figure can be used to maintain the DC link capacitor voltage at a preset constant value on the one hand, and on the other hand, control the reactive power generated to a set reference value according to the reactive power requirements of the entire wind turbine. Figure 3 As shown, is the DC capacitor voltage operating value, is the DC capacitor voltage target value, is the d-axis current operating value, is the d-axis current target value, is the q-axis current operating value, is the q-axis current target value, is the reactive output measurement value of the machine end, is the reactive power output target value of the machine end, The grid-side converter outputs a d-axis modulation signal, The grid-side converter outputs the q-axis modulation signal, and SVRF represents the stator voltage reference coordinate system.

[0060] Step 2: measure the machine-side voltage output by the machine-side converter, and obtain the dq components of the voltage in the control coordinate system of the grid-side converter after the machine-side voltage passes through the phase-locked link.

[0061] Step 3: Design the additional damping control strategy for the grid-side converter. Figure 4 As shown, the dq component of the terminal voltage (i.e., U sd and U sp ) pass through the equivalent resistor respectively and then output the current command for additional damping control.

[0062] Step 4: Design the equivalent resistance value of the additional damping control of the grid-side converter.

[0063] If the equivalent resistance value is designed to be too small, the suppression effect of the additional damping control on subsynchronous oscillations will be weakened. However, if the equivalent resistance value is designed to be too large, when the grid voltage contains a small subsynchronous oscillation component, it will lead to a large additional current control output, affecting the DC capacitor voltage control and reactive power control of the grid-side converter. The equivalent resistance value designed in this application is between 0.2 and 1.

[0064] Step 5: Design the additional damping control strategy for the grid-side converter. Figure 4 As shown, the additional damping control current command output is limited to output igd_s and igq_s. Among them, i_max and i_min are per-unit values, and the absolute value should not be greater than 1. In this application, the per-unit values ​​of i_max and i_min are set to 0.5 and -0.5 respectively.

[0065] Step 6: Design the grid-side converter additional damping control strategy, such as Figure 4As shown, the additional damping control current command after limiting is superimposed on the output current command of normal operation control (i.e. and )superior.

[0066] Through the above steps, additional damping control can be achieved without adding an additional filter after the input voltage signal, which does not affect the control structure of the existing doubly-fed wind turbine. It is easy to implement and is also conducive to reducing the complexity of the machine-side converter control strategy. In addition, since the filter has different delays for different oscillation frequencies, no additional filter is introduced, which avoids weakening the damping effect on subsynchronous oscillations after the introduction of the filter. Furthermore, this solution performs damping control from the perspective of control parameter design, reducing dependence on subsynchronous oscillation modes. In this way, applying the technical solution of the present application in actual scenarios can significantly improve the operating efficiency of wind turbines and reduce maintenance costs, which is of great significance to promoting the development and utilization of wind energy resources.

[0067] Furthermore, in one embodiment, a simulation is performed on a double-fed wind farm to verify the control effect through the series compensation transmission wind power system. Modification is made based on the IEEE first standard model, such as Figure 5 As shown, R L1 and X L1 are the equivalent resistance and equivalent reactance of the 220kV transmission line, R L2 , X L2 and X C They are the equivalent resistance, equivalent reactance and series compensation capacitor reactance of the 550kV transmission line, X Z is the equivalent impedance of the infinite power grid. T1 is a 35 / 220kV transformer, and T2 is a 220 / 500kV transformer. The rated capacity of the infinite system is 892.4MW, the line series compensation is set to 33.3%, and the doubly fed wind farm adopts a multiplied equivalent model of 100 1.5MW doubly fed wind turbines. The control system includes power outer loop and current inner loop control, and the wind speed is set to 15m / s.

[0068] In the simulation process, the series compensation capacitor can be put into use at 0s to analyze the subsynchronous oscillation phenomenon after the system is disturbed. Figure 6 As shown, when the subsynchronous oscillation damping control strategy based on the grid-side converter equivalent resistance design in this application is not applied, the doubly-fed wind turbine system shows a subsynchronous oscillation frequency curve shown by the blue curve. The Prony algorithm is further used to identify the simulation curve, and the oscillation frequency of the oscillation mode corresponding to the blue curve is 34.69Hz, and the damping ratio is -2.36%. At this time, the system has subsynchronous oscillations due to insufficient damping, and after a period of divergence, it begins to oscillate with equal amplitude due to the limiting effect of the controller parameters. After applying the subsynchronous oscillation damping control strategy based on the grid-side converter equivalent resistance design in this application, as shown Figure 6 As shown by the red curve in , the system's damping of subsynchronous oscillations is significantly enhanced, and the subsynchronous oscillation components decay rapidly.

[0069] Through the description of the above implementation methods, those skilled in the art can clearly understand that the method according to the above embodiment can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk), and includes a number of instructions for a terminal device (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods of each embodiment of the present application.

[0070] In this embodiment, a control device for a grid-side converter is also provided, which is used to implement the above-mentioned embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceivable.

[0071] Figure 7 is a structural block diagram of a control device for a grid-side converter according to an embodiment of the present application, the device comprising:

[0072] A determination module 72, configured to determine a target control circuit set for the grid-side converter, wherein the target control circuit includes at least an equivalent resistance circuit and an initial control circuit, wherein the equivalent resistance circuit is used for performing additional damping control, and the initial control circuit represents a circuit set according to an initial control strategy;

[0073] An acquisition module 74 is used to acquire a dq component of the machine-side voltage in the control coordinate system of the grid-side converter after the machine-side voltage passes through a phase-locked link, wherein the machine-side voltage is output by the machine-side converter of the doubly-fed wind turbine generator set;

[0074] An obtaining module 76 is used to input the dq component of the machine-end voltage into the target control circuit to obtain a target current output by the target control circuit, wherein the target current at least includes a first current of the additional damping control output by the equivalent resistance circuit and a second current output by the initial control circuit;

[0075] The control module 78 is configured to control the output current of the grid-side converter based on the current command generated by the target current.

[0076] Through the above-mentioned device, by determining the target control circuit set for the grid-side converter, the target control circuit at least includes an equivalent resistance circuit and an initial control circuit, the equivalent resistance circuit is used for additional damping control, and the initial control circuit represents a circuit set according to the initial control strategy; obtaining the dq component of the machine-end voltage in the control coordinate system of the grid-side converter after the machine-end voltage passes through the phase-locked link, the machine-end voltage is output by the machine-side converter of the doubly fed wind turbine generator set; inputting the dq component of the machine-end voltage into the target control circuit to obtain the target current output by the target control circuit, the target current at least includes the first current of the additional damping control output by the equivalent resistance circuit, and the second current output by the initial control circuit; and controlling the output current of the grid-side converter based on the current instruction generated by the target current. The present application solves the technical problem of not being able to effectively control the subsynchronous oscillation of the doubly fed wind turbine when it is connected to the grid by introducing an equivalent resistance circuit into the control circuit of the grid-side converter for additional damping control, improves the control efficiency of the subsynchronous oscillation of the doubly fed wind turbine when it is connected to the grid, effectively suppresses the subsynchronous oscillation of the doubly fed wind turbine when it is connected to the grid, and thereby improves the stability of the doubly fed wind turbine when it is connected to the grid.

[0077] In an exemplary embodiment, the determination module is also used to: add the equivalent resistance circuit to the initial control circuit to obtain the target control circuit, wherein the initial control circuit at least includes a DC voltage outer loop circuit and a current inner loop circuit, the equivalent resistance circuit and the DC voltage outer loop circuit are connected in parallel, and the target control circuit is used to provide a constant DC capacitor voltage value.

[0078] In an exemplary embodiment, the equivalent resistance circuit is used to provide an expected per-unit value of resistance, and the expected per-unit value has a value range of [0.2, 1].

[0079] In an exemplary embodiment, the determination module is further used to: obtain a target reactive power preset for the doubly-fed wind turbine generator set, and control the reactive power generated by the target control circuit to be consistent with the power value of the target reactive power.

[0080] In an exemplary embodiment, the control module is also used to: before controlling the output current of the grid-side converter based on the current instruction generated by the target current, limit the first current to obtain a third current, wherein the per-unit value of the current limit value of the third current belongs to a preset range; determine the target current based on the third current and the second current, and generate a current instruction according to the target current.

[0081] In an exemplary embodiment, the control module is further used to: generate a first control instruction based on the second current, generate a second control instruction according to the third current, and generate the current instruction according to the first control instruction and the second control instruction.

[0082] An embodiment of the present application further provides a computer-readable storage medium, in which a computer program is stored, wherein the computer program is configured to execute the steps of any of the above method embodiments when run.

[0083] Optionally, in this embodiment, the storage medium may be configured to store a computer program for performing the following steps:

[0084] S1, determining a target control circuit set for the grid-side converter, the target control circuit comprising at least an equivalent resistance circuit and an initial control circuit, the equivalent resistance circuit being used for additional damping control, and the initial control circuit representing a circuit set according to an initial control strategy;

[0085] S2, obtaining the dq component of the machine-side voltage in the control coordinate system of the grid-side converter after the machine-side voltage passes through the phase-locked link, wherein the machine-side voltage is output by the machine-side converter of the doubly-fed wind turbine generator set;

[0086] S3, inputting the dq component of the machine-end voltage into the target control circuit to obtain a target current output by the target control circuit, wherein the target current at least includes a first current of the additional damping control output by the equivalent resistance circuit and a second current output by the initial control circuit;

[0087] S4, controlling the output current of the grid-side converter based on the current command generated by the target current.

[0088] In an exemplary embodiment, the computer-readable storage medium may include, but is not limited to, various media that can store computer programs, such as a USB flash drive, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk.

[0089] For specific examples in this embodiment, reference may be made to the examples described in the above embodiments and exemplary implementation modes, and this embodiment will not be described in detail herein.

[0090] An embodiment of the present application further provides an electronic device, including a memory and a processor, wherein a computer program is stored in the memory, and the processor is configured to run the computer program to execute the steps in any one of the above method embodiments.

[0091] Optionally, in this embodiment, the processor may be configured to perform the following steps through a computer program:

[0092] S1, determining a target control circuit set for the grid-side converter, the target control circuit comprising at least an equivalent resistance circuit and an initial control circuit, the equivalent resistance circuit being used for additional damping control, and the initial control circuit representing a circuit set according to an initial control strategy;

[0093] S2, obtaining the dq component of the machine-side voltage in the control coordinate system of the grid-side converter after the machine-side voltage passes through the phase-locked link, wherein the machine-side voltage is output by the machine-side converter of the doubly-fed wind turbine generator set;

[0094] S3, inputting the dq component of the machine-end voltage into the target control circuit to obtain a target current output by the target control circuit, wherein the target current at least includes a first current of the additional damping control output by the equivalent resistance circuit and a second current output by the initial control circuit;

[0095] S4, controlling the output current of the grid-side converter based on the current command generated by the target current.

[0096] In an exemplary embodiment, the electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor, and the input / output device is connected to the processor.

[0097] An embodiment of the present application further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the steps in any one of the above method embodiments are implemented.

[0098] An embodiment of the present application further provides another computer program product, including a non-volatile computer-readable storage medium, wherein the non-volatile computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps in any of the above method embodiments are implemented.

[0099] An embodiment of the present application also provides a computer program, which includes computer instructions, which are stored in a computer-readable storage medium; a processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs the steps in any one of the above method embodiments.

[0100] For specific examples in this embodiment, reference may be made to the examples described in the above embodiments and exemplary implementation modes, and this embodiment will not be described in detail herein.

[0101] Obviously, those skilled in the art should understand that the above modules or steps of the present application can be implemented by a general computing device, they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, and in some cases, the steps shown or described can be executed in a different order from that herein, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present application is not limited to any specific combination of hardware and software.

[0102] The above is only a preferred implementation of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A control method for a grid-side converter, characterized in that: The grid-side converter belongs to a doubly-fed wind turbine set, and the doubly-fed wind turbine set also includes a machine-side converter, including: Determine a target control circuit set for the grid-side converter, the target control circuit at least comprising an equivalent resistance circuit and an initial control circuit, the equivalent resistance circuit being used for additional damping control, and the initial control circuit representing a circuit set according to an initial control strategy; Obtaining a dq component of the machine-side voltage in the control coordinate system of the grid-side converter after the machine-side voltage passes through a phase-locked link, wherein the machine-side voltage is output by the machine-side converter of the doubly-fed wind turbine generator set; Inputting the dq component of the machine-end voltage into the target control circuit to obtain a target current output by the target control circuit, wherein the target current at least includes a first current of the additional damping control output by the equivalent resistance circuit and a second current output by the initial control circuit; The current command generated based on the target current controls the output current of the grid-side converter.

2. The method according to claim 1, characterized in that Determining a target control circuit to be set for the grid-side converter includes: The equivalent resistance circuit is newly added to the initial control circuit to obtain the target control circuit, wherein the initial control circuit at least includes a DC voltage outer loop circuit and a current inner loop circuit, the equivalent resistance circuit and the DC voltage outer loop circuit are connected in parallel, and the target control circuit is used to provide a constant DC capacitor voltage value.

3. The method according to claim 2, characterized in that The equivalent resistance circuit is used to provide an expected per-unit value of resistance, and the expected per-unit value has a value range of [0.2, 1].

4. The method according to claim 1, characterized in that: The method further comprises: A target reactive power preset for the doubly-fed wind turbine set is acquired, and the reactive power generated by the target control circuit is controlled to be consistent with a power value of the target reactive power.

5. The method according to claim 4, characterized in that Before controlling the output current of the grid-side converter based on the current command generated by the target current, the method further includes: Performing a limiting operation on the first current to obtain a third current, wherein a per-unit value of the current limiting value of the third current falls within a preset range; The target current is determined based on the third current and the second current, and a current command is generated according to the target current.

6. The method according to claim 5, characterized in that Generating a current instruction based on the target current includes: A first control instruction is generated based on the second current, a second control instruction is generated according to the third current, and the current instruction is generated according to the first control instruction and the second control instruction.

7. A control device for a grid-side converter, characterized in that: include: a determination module, configured to determine a target control circuit set for the grid-side converter, wherein the target control circuit comprises at least an equivalent resistance circuit and an initial control circuit, wherein the equivalent resistance circuit is used for performing additional damping control, and the initial control circuit represents a circuit set according to an initial control strategy; An acquisition module, used for acquiring a dq component of a machine-side voltage in a control coordinate system of the grid-side converter after the machine-side voltage passes through a phase-locked link, wherein the machine-side voltage is output by the machine-side converter of the doubly-fed wind turbine generator set; An obtaining module, used for inputting the dq component of the machine-end voltage into the target control circuit to obtain a target current output by the target control circuit, wherein the target current at least includes a first current of the additional damping control output by the equivalent resistance circuit and a second current output by the initial control circuit; A control module is used to control the output current of the grid-side converter based on the current instruction generated by the target current.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein the program executes the method according to any one of claims 1 to 6 when executed.

9. An electronic device comprising a memory and a processor, characterized in that: A computer program is stored in the memory, and the processor is configured to execute the method according to any one of claims 1 to 6 through the computer program.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 6 are implemented.

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