Rectifier control method and device, equipment and storage medium

Abstract

The invention discloses a rectifier control method, device and equipment and a storage medium, and the method comprises the steps: carrying out the differential coupling of a capacitor voltage in a process of controlling a rectifier, so as to obtain a control quantity of a capacitor current, carrying out the high-frequency filtering of the control quantity of the capacitor current, extracting a high-frequency harmonic current from the capacitor current, and carrying out the high-frequency filtering of the high-frequency harmonic current; active damping gain control is carried out on high-frequency harmonic current to obtain an active damping gain control output compensation value, and then primary modulation voltage output by a current loop in voltage and current double-closed-loop control is compensated based on the active damping gain control output compensation value to obtain target modulation voltage. And then the rectifier is controlled according to a target modulation signal generated by the target modulation voltage, so that normal work of the rectifier is ensured, virtual damping generated by the high-frequency harmonic current is introduced when the rectifier is controlled, high-frequency harmonic energy is consumed through the virtual damping, suppression of the high-frequency harmonic current is realized, and the stability of the system is improved.

Description

Technical Field

[0001] The present invention relates to the field of voltage conversion control, and in particular to a rectifier control method, device, equipment and storage medium. Background Art

[0002] A PWM (Pulse Width Modulation) rectifier is a high-performance power electronic device based on pulse width modulation technology that converts AC power into DC power. Because PWM rectifiers convert AC power into DC power through high-frequency switching, the switching action generates high-frequency harmonics. Therefore, each phase of a traditional PWM rectifier is connected to the power grid through an L filter. Because the inductor presents high impedance to high-frequency harmonics, it effectively attenuates these high-frequency current components, reducing harmonic pollution to the power grid and electromagnetic interference. However, due to the limited inductance of the L filter, the L filter cannot suppress higher-frequency harmonics. Therefore, in existing technology, LCL filters are also used to replace L filters when connected to the power grid. This achieves better filtering effect by suppressing higher-frequency harmonics with smaller capacitance and inductance values. However, because LCL filters resonate at high frequencies, inappropriate filter design or control strategy can cause system instability. Summary of the Invention

[0003] The purpose of the present invention is to provide a rectifier control method, device, equipment and storage medium, which introduce virtual damping generated by high-frequency harmonic current when controlling the rectifier, consume high-frequency harmonic energy through virtual damping, achieve suppression of high-frequency harmonic current, and improve system stability.

[0004] To solve the above technical problems, the present invention provides a rectifier control method, comprising:

[0005] Get the grid voltage reference angle;

[0006] Perform coordinate transformation on the capacitor voltage according to the grid voltage reference angle to obtain the dq axis components of the capacitor voltage;

[0007] The dq axis components of the capacitor voltage are differentially coupled to obtain the dq axis control quantity of the capacitor current;

[0008] Perform high-frequency filtering on the dq-axis control quantity of the capacitor current to obtain the high-frequency harmonic current in the capacitor current;

[0009] Active damping gain control is performed based on high-frequency harmonic current in the capacitor current to obtain an active damping gain control output compensation value;

[0010] The primary modulation voltage output by the current loop in the voltage-current dual closed-loop control is compensated based on the active damping gain control output compensation value to obtain a target modulation voltage, and a target modulation signal is generated according to the target modulation voltage to control the rectifier.

[0011] Preferably, obtaining the grid voltage reference angle includes:

[0012] The capacitor voltage is phase-locked using a phase-locked loop to obtain the grid voltage reference angle.

[0013] Preferably, an LCL filter is provided between the rectifier and the grid; differential coupling is performed on the dq-axis components of the capacitor voltage to obtain the dq-axis control quantity of the capacitor current, including:

[0014] Differentiate the dq-axis components of the capacitor voltage to obtain the dq-axis components of the capacitor current;

[0015] The dq axis components of the capacitor current are coupled to obtain the dq axis control quantity of the capacitor current;

[0016] Among them, the expression of the dq-axis control quantity of the capacitor current is as follows:

[0017] ;

[0018] in, is the d-axis control quantity of the capacitor current, is the q-axis control quantity of the capacitor current, is the angular velocity of the dq coordinate system, is the capacitance in the LCL filter, is the d-axis component of the capacitor voltage, is the q-axis component of the capacitor voltage.

[0019] Preferably, an LCL filter is provided between the rectifier and the power grid; high-frequency filtering is performed on the dq-axis control quantity of the capacitor current to obtain high-frequency harmonic current in the capacitor current, including:

[0020] Determine the resonant frequency of the LCL filter based on the inductance and capacitance in the LCL filter;

[0021] The cutoff frequency of the high-pass filter is set based on the resonant frequency, so that the dq-axis control amount of the capacitor current is subjected to high-frequency filtering by the high-pass filter to obtain high-frequency harmonic current in the capacitor current.

[0022] Preferably, active damping gain control is performed based on the high-frequency harmonic current in the capacitor current to obtain an active damping gain control output compensation value, including:

[0023] The high-frequency harmonic current in the capacitor current is multiplied by the active damping gain to obtain the active damping gain control output compensation value.

[0024] Preferably, the compensating the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control based on the active damping gain control output compensation value to obtain the target modulation voltage includes:

[0025] Compensating the d-axis component of the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control based on the d-axis component in the active damping gain control output compensation value to obtain the d-axis component of the target modulation voltage;

[0026] The q-axis component of the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control is compensated based on the q-axis component in the active damping gain control output compensation value to obtain the q-axis component of the target modulation voltage.

[0027] Preferably, generating a target modulation signal according to the target modulation voltage to control the rectifier includes:

[0028] Performing coordinate transformation of the d-axis component and the q-axis component of the target modulation voltage to the target modulation voltage in a stationary coordinate system;

[0029] A target modulation signal is generated based on a target modulation voltage in a stationary coordinate system, and the rectifier is controlled based on the target modulation signal.

[0030] To solve the above technical problems, the present invention provides a rectifier control system, comprising:

[0031] An acquisition module is used to obtain a grid voltage reference angle;

[0032] A coordinate transformation module is used to perform coordinate transformation on the capacitor voltage according to the grid voltage reference angle to obtain the dq axis components of the capacitor voltage;

[0033] A differential module is used to differentiate the dq-axis components of the capacitor voltage to obtain the dq-axis control quantity of the capacitor current;

[0034] The high-frequency filtering module is used to perform high-frequency filtering on the dq-axis control quantity of the capacitor current to obtain the high-frequency harmonic current in the capacitor current;

[0035] An active damping module is used to perform active damping gain control based on high-frequency harmonic current in the capacitor current to obtain an active damping gain control output compensation value;

[0036] The compensation control module is used to compensate the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control based on the active damping gain control output compensation value to obtain the target modulation voltage, and generate a target modulation signal according to the target modulation voltage to control the rectifier.

[0037] To solve the above technical problems, the present invention provides a rectifier control device, comprising:

[0038] memory for storing computer programs;

[0039] The processor is configured to implement the steps of the rectifier control method as described above when executing the computer program.

[0040] To solve the above technical problems, the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the rectifier control method as described above are implemented.

[0041] The present application provides a rectifier control method, apparatus, device and storage medium. In the process of controlling the rectifier, the capacitor voltage is differentially coupled to obtain the control amount of the capacitor current. After the capacitor current control amount is high-frequency filtered, the high-frequency harmonic current is extracted from the capacitor current. By actively damping the high-frequency harmonic current, an active damping gain control output compensation value is obtained. Then, based on the active damping gain control output compensation value, the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control is compensated to obtain the target modulation voltage. The rectifier is then controlled according to the target modulation signal generated by the target modulation voltage. While ensuring the normal operation of the rectifier, virtual damping generated by the high-frequency harmonic current is introduced when controlling the rectifier. The high-frequency harmonic energy is consumed by the virtual damping, thereby suppressing the high-frequency harmonic current and improving the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0043] Figure 1 A flow chart of a rectifier control method provided in this application;

[0044] Figure 2 A control strategy block diagram provided for this application;

[0045] Figure 3 A connection diagram of an LCL filter provided in this application;

[0046] Figure 4 This is a schematic diagram of a current change waveform when no-load is provided in this application;

[0047] Figure 5 A schematic diagram of a current change waveform during loading provided by this application;

[0048] Figure 6 A schematic structural diagram of a rectifier control device provided in this application;

[0049] Figure 7 A schematic structural diagram of a rectifier control device provided in this application;

[0050] Figure 8 A schematic diagram of a computer-readable storage medium provided for this application. DETAILED DESCRIPTION

[0051] The core of the present invention is to provide a rectifier control method, device, equipment and storage medium, which ensure the normal operation of the rectifier while introducing virtual damping generated by high-frequency harmonic current when controlling the rectifier. The virtual damping consumes the high-frequency harmonic energy, thereby suppressing the high-frequency harmonic current and improving the stability of the system.

[0052] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0053] Please refer to Figure 1 , Figure 1 A schematic flow chart of a rectifier control method provided in this application, the method comprising:

[0054] S11: Obtain the grid voltage reference angle.

[0055] S12: Performing coordinate transformation on the capacitor voltage according to the grid voltage reference angle to obtain dq-axis components of the capacitor voltage.

[0056] A rectifier is a device that converts AC power into DC power. It primarily converts AC power from the grid into the DC power required by electrical devices. Specifically, the rectifier uses high-frequency switching devices, such as IGBTs (Insulated-Gate Bipolar Transistors) and MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors), to rapidly switch on and off to control the output current waveform, ensuring it follows the sinusoidal waveform of the grid voltage. However, the switching action itself causes sudden, sudden changes in current, which in turn leads to the presence of high-frequency components in the current waveform, known as high-frequency harmonics. These harmonics are not fully absorbed by the load and instead flow back into the grid through the connection point between the rectifier and the grid, causing harmonic pollution. Therefore, conventional techniques typically place a filter inductor, also known as an L-type filter, between the grid and the rectifier. However, a filter inductor with a low inductance cannot effectively filter out harmonics. Therefore, a filter inductor with a larger inductance is required, which undoubtedly increases costs. Therefore, LCL filters can be used to replace L-type filters. This filtering method uses an inductor-capacitor-inductor filter to filter harmonics. Based on this, the inductor does not need to be large and can still achieve good filtering effect. However, LCL filters will also resonate at high frequencies. If the filter design or control strategy is not appropriate, the harmonics generated by the LCL filter can cause instability in the entire system.

[0057] When controlling a rectifier, it is necessary to consider that in the abc three-phase stationary coordinate system, the input-output relationship of the rectifier is a complex nonlinear system. For example, the input of the rectifier is a three-phase AC voltage and the output is a DC voltage. Its dynamic equation involves coupling between multiple phases. If the control quantity is converted into a quantity in the dq coordinate system, this multi-variable strongly coupled system can be converted into two independent DC components, namely the control problem of the d-axis component and the q-axis component.

[0058] Based on this, in this application, the grid voltage reference angle is first obtained. Since the phase of the capacitor voltage is consistent with the phase of the grid voltage, the capacitor voltage can be directly transformed according to the grid voltage reference angle to obtain the dq-axis components of the capacitor voltage.

[0059] S13: differentially couple the dq-axis components of the capacitor voltage to obtain the dq-axis control quantity of the capacitor current.

[0060] When determining the dq-axis control quantity of the capacitor current, the dq-axis components of the capacitor voltage are differentially coupled, and the capacitor voltage and capacitor current satisfy the differential relationship:

[0061] ;

[0062] in, is the capacitance in the LCL filter, is the capacitor current, is the capacitor voltage. And because in the rotating dq coordinate system, the dq coordinate system itself is Rotation, any variable in the stationary coordinate system will show additional dynamic coupling in the dq coordinate system, that is, when the dq coordinate system rotates at an angular velocity During rotation, the d-axis component and the q-axis component of the originally stationary grid voltage sampling value will generate a "virtual speed" component due to the rotation. Therefore, while differentiating the d-axis and q-axis components of the capacitor voltage, coupling must also be added to determine the d-axis control amount of the capacitor current.

[0063] S14: Perform high-frequency filtering on the dq-axis control quantity of the capacitor current to obtain high-frequency harmonic current in the capacitor current.

[0064] In order to capture high-frequency harmonic currents in the capacitor current, high-frequency filtering is performed on the dq-axis control variables of the capacitor current. Specifically, high-frequency filtering means eliminating low-frequency currents in the capacitor current and retaining high-frequency harmonic currents.

[0065] S15: performing active damping gain control based on the high-frequency harmonic current in the capacitor current to obtain an active damping gain control output compensation value.

[0066] When controlling the rectifier, a modulation signal is mainly generated based on the modulation voltage to drive the rectifier. Therefore, the high-frequency harmonic current in the capacitor current obtained after high-frequency filtering is also actively damped and gain controlled to generate an active damping gain control output compensation value, so that voltage compensation can be subsequently performed based on the active damping gain control output compensation value, and a target modulation signal for driving the rectifier is generated.

[0067] It should be noted that by performing active damping control on high-frequency harmonic currents, the generated active damping gain control output compensation value introduces virtual damping into the system. When high-frequency harmonic currents exist, the virtual damping consumes the high-frequency harmonic energy in the system to suppress high-frequency harmonics.

[0068] S16: Compensating the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control based on the active damping gain control output compensation value to obtain a target modulation voltage, and generating a target modulation signal according to the target modulation voltage to control the rectifier.

[0069] Considering that the rectifier is controlled through dual closed-loop voltage and current control, that is, through a current loop and a voltage loop, with the voltage loop acting as the outer loop, regulating the DC bus voltage to a set value and outputting a current reference signal for the current loop. The current loop acts as the inner loop, tracking the current reference signal output by the voltage loop, generating a primary modulation voltage and converting it into a modulation signal to control the switching devices in the rectifier, in this embodiment, after generating the active damping gain control output compensation value, the active damping gain control output compensation value can be used to compensate the primary modulation voltage output by the current loop. Since the active damping gain control output compensation value is generated after active damping gain control is performed on the high-frequency harmonic current, virtual damping can be added to the primary modulation voltage, that is, a damping control signal is introduced into the current loop. This damping control signal is similar to a virtual damping resistor, which can dissipate oscillation energy in the system and thus suppress resonance in the system. Compared with directly adding resistors in series or parallel to the LCL filter to increase system damping, the present invention can not only stably and reliably suppress resonance in the system, but also does not increase system losses or reduce system operating efficiency. It is suitable for resonance suppression in high-power systems.

[0070] Specifically, the process of voltage and current dual closed-loop control is:

[0071] Acquire the sampled grid voltage, and perform phase locking on the grid voltage based on a phase-locked loop to obtain a grid voltage reference angle of the grid voltage;

[0072] detecting an actual value of the DC voltage of the rectifier and determining a DC voltage error of the voltage loop based on a set value of the DC voltage;

[0073] The DC voltage error value is adjusted by the voltage loop PI controller, and the d-axis reference current and q-axis reference current of the current loop are output;

[0074] Performing coordinate transformation on the sampled grid current based on the grid voltage reference angle to determine the d-axis component and the q-axis component of the grid current sampling value;

[0075] Calculate the d-axis current error value based on the d-axis reference current and the d-axis component of the grid current sampling value;

[0076] Calculate the q-axis current error value based on the q-axis reference current and the q-axis component of the grid current sampling value;

[0077] The d-axis current error value and the d-axis current error value are error-adjusted respectively by the current loop PI controller, and the d-axis component and the q-axis component of the primary modulation voltage are generated;

[0078] Based on the active damping gain control output compensation value, the d-axis component and the q-axis component of the primary modulation voltage are compensated respectively. After the target modulation voltage is obtained, the rectifier is controlled according to the target modulation signal generated by the target modulation voltage.

[0079] Please refer to Figure 2 , Figure 2 A control strategy block diagram is provided for this application. Specifically, the voltage loop serves as the outer loop, and the grid voltage reference angle of the sampled grid voltage is first determined through a phase-locked loop. That is, according to the grid voltage reference angle, the current or voltage output by the system can be kept in phase with the grid voltage, thereby improving the power quality of the system.

[0080] The voltage loop primarily regulates the DC bus voltage to a set value and outputs a current reference signal for the current loop. Therefore, the voltage loop also subtracts the actual DC voltage value of the rectifier from the set DC voltage value to determine the DC voltage error—the difference between the actual DC voltage value and the set DC voltage value. After the DC voltage error is PI-regulated by the voltage loop's PI controller, it outputs the d-axis reference current and q-axis reference current for the current loop. The current loop first transforms the grid current based on the grid voltage reference angle to generate grid current sampling values in the dq coordinate system, including the d-axis and q-axis components. To ensure that the actual DC voltage value of the controller is equal to the set DC voltage value after driving, the d-axis current error between the d-axis component of the grid current sampling value and the d-axis reference current, as well as the q-axis current error between the q-axis component of the grid current sampling value and the q-axis reference current, must be calculated. The d-axis current error value and the q-axis current error value are then error-adjusted through the current loop PI controller to generate the d-axis component and the q-axis component of the primary modulation voltage. Based on this, the rectifier is controlled after the d-axis component and the q-axis component of the primary modulation voltage are compensated based on the output compensation value based on the active damping gain control, so that the actual DC voltage value of the rectifier is the DC voltage set value and high-frequency harmonics are suppressed.

[0081] in, Figure 2 The PLL in it is a phase-locked loop. is the grid voltage reference angle, is the DC voltage setting value, is the actual value of DC voltage, PI1 is the voltage loop PI controller, is the d-axis reference current, is the q-axis reference current, is the grid current, is the d-axis component of the grid current sampling value, is the q-axis component of the grid current sampling value, and PI2 is the current loop PI controller.

[0082] It should be noted that the grid voltage sampled during the voltage and current dual closed-loop control process can be used as the capacitor voltage to calculate the capacitor current. Based on this, there is no need for an additional current sensor and its signal conditioning circuit. The current sensor and its signal conditioning circuit are relatively expensive, and the current sensor is easily affected by electromagnetic interference. The current sensor and its signal conditioning circuit cannot guarantee the accuracy of the current value directly collected. Therefore, in this embodiment, there is no need to use a current sensor to collect the capacitor current in the LCL filter, but it is directly calculated through the grid voltage, which reduces the cost and improves the accuracy of the dq-axis control quantity of the calculated capacitor current.

[0083] In summary, in this application, while ensuring the normal operation of the rectifier, virtual damping generated by high-frequency harmonic current is introduced when controlling the rectifier. The high-frequency harmonic energy is consumed by virtual damping, thereby suppressing the high-frequency harmonic current and improving the stability of the system.

[0084] Based on the above embodiment:

[0085] As a preferred embodiment, obtaining the grid voltage reference angle includes:

[0086] The capacitor voltage is phase-locked using a phase-locked loop to obtain the grid voltage reference angle.

[0087] The capacitor voltage is phase-locked using a phase-locked loop to obtain the grid voltage synchronization angle. Compared with directly phase-locking the grid voltage, it is less susceptible to grid harmonic distortion, LCL resonance spikes, and voltage drop transient impacts.

[0088] As a preferred embodiment, an LCL filter is provided between the rectifier and the grid; differential coupling is performed on the dq-axis components of the capacitor voltage to obtain the dq-axis control quantity of the capacitor current, including:

[0089] Differentiate the dq-axis components of the capacitor voltage to obtain the dq-axis components of the capacitor current;

[0090] The dq axis components of the capacitor current are coupled to obtain the dq axis control quantity of the capacitor current;

[0091] Among them, the expression of the dq-axis control quantity of the capacitor current is as follows:

[0092] ;

[0093] in, is the d-axis control quantity of the capacitor current, is the q-axis control quantity of the capacitor current, is the angular velocity of the dq coordinate system, is the capacitance in the LCL filter, is the d-axis component of the capacitor voltage, is the q-axis component of the capacitor voltage.

[0094] When differential coupling is performed on the dq-axis components of the capacitor voltage to obtain the dq-axis control quantity of the capacitor current, the expression of the dq-axis control quantity of the capacitor current is:

[0095] ;

[0096] in, is the d-axis control quantity of the capacitor current, is the q-axis control variable of the capacitor current, s is the complex frequency variable, is the angular velocity of the dq coordinate system, is the capacitance value in the LCL filter, is the d-axis component of the capacitor voltage, is the q-axis component of the capacitor voltage;

[0097] By differentiating the d-axis component and q-axis component of the capacitor voltage, the static component of the capacitor current in the LCL filter can be obtained. Rotation, any variable in the stationary coordinate system will show additional dynamic coupling in the dq coordinate system, that is, when the dq coordinate system rotates at an angular velocity During rotation, the d-axis component of the capacitor voltage and the q-axis component of the capacitor voltage, which were originally stationary, will generate a "virtual speed" component due to rotation. This rotation effect causes the d-axis control amount of the capacitor current to be subtracted. ; The q-axis control quantity of the capacitor current needs to be added , to compensate for the coupling caused by rotation.

[0098] Please refer to Figure 2 , Figure 2 in is the d-axis component of the capacitor voltage, is the q-axis component of the capacitor voltage, To perform integration, is the d-axis control quantity of the capacitor current, is the q-axis control quantity of the capacitor current, obtained after filtering with a high-pass filter is the d-axis component of the high-frequency harmonic current, is the q-axis component of the high-frequency harmonic current, k is the active damping gain control, specifically the active damping gain, is the d-axis component of the active damping gain control output compensation value, is the q-axis component of the active damping gain control output compensation value, is the d-axis component of the target modulation voltage, is the q-axis component of the target modulation voltage.

[0099] When differential coupling is performed on the d-axis and q-axis components of the capacitor voltage, it is considered that the high-frequency noise in any signal will be significantly amplified when passing through the differential link. Therefore, the differential link will bring additional high-frequency noise to the system, which may cause the system in the resonant state to become more unstable. Based on this, in this embodiment, the differential link is ignored, and only the d-axis component and the q-axis component of the grid voltage sampling value are coupled respectively. The expression of the d-axis and q-axis control quantity of the capacitor current after ignoring the differential link is:

[0100] .

[0101] As a preferred embodiment, an LCL filter is provided between the rectifier and the power grid; high-frequency filtering is performed on the dq-axis control quantity of the capacitor current to obtain high-frequency harmonic current in the capacitor current, including:

[0102] Determine the resonant frequency of the LCL filter based on the inductance and capacitance in the LCL filter;

[0103] The cutoff frequency of the high-pass filter is set based on the resonant frequency, so that the dq-axis control amount of the capacitor current is subjected to high-frequency filtering by the high-pass filter to obtain high-frequency harmonic current in the capacitor current.

[0104] Because the LCL filter has the lowest impedance at the resonant frequency, the system is prone to violent current or voltage oscillations. Therefore, in this application, damping is introduced when resonance occurs to suppress resonance near the resonant frequency. Based on this, the resonant frequency of the LCL filter is calculated based on the hardware structure parameters of the LCL filter, that is, the size of the inductance and capacitance set in the LCL filter.

[0105] For details, please refer to Figure 3 , Figure 3The present application provides a connection diagram of an LCL filter, wherein the LCL filter includes a grid-side inductor, a machine-side inductor, and a filter capacitor. The first end of the a-phase grid-side inductor is connected to the a-phase line of the grid, and the second end is connected to the first end of the a-camera-side inductor. The second end of the a-camera-side inductor is connected to the a-phase line of the rectifier. The first end of the a-phase filter capacitor is connected to the second end of the a-phase grid-side inductor and the first end of the a-camera-side inductor, and the second end is connected to the neutral point; the first end of the b-phase grid-side inductor is connected to the b-phase line of the grid, and the second end is connected to the b-camera-side inductor. The first end of the inductor on the b-phase side is connected to the b-phase line of the rectifier, the second end of the inductor on the b-phase side is connected to the b-phase line of the rectifier, the first end of the filter capacitor on the b-phase side is connected to the second end of the inductor on the b-phase side and the first end of the inductor on the b-camera side, and the second end is connected to the neutral point; the first end of the inductor on the c-phase side is connected to the c-phase line of the power grid, the second end is connected to the first end of the inductor on the c-camera side, the second end of the inductor on the c-camera side is connected to the c-phase line of the rectifier, the first end of the filter capacitor on the c-phase side is connected to the second end of the inductor on the c-phase side and the first end of the inductor on the c-camera side, and the second end is connected to the neutral point. It should be noted that Figure 2 in is the a-phase grid voltage, is the b-phase grid voltage, is the c-phase grid voltage, is the a-phase output current of the rectifier, is the b-phase output current of the rectifier, is the c-phase output current of the rectifier, is the DC voltage of the rectifier, is the capacitor voltage, corresponding to each phase grid voltage.

[0106] When current flows through the grid-side and generator-side inductors in an LCL filter, they store energy. For low-frequency fundamental currents, the inductive reactance of these inductors is relatively small, allowing the fundamental current to pass through them easily with minimal losses. However, for high-frequency harmonic currents, the inductive reactance of these inductors is larger, blocking the passage of these high-frequency harmonic currents and preventing them from entering subsequent circuits. A filter capacitor, connected between the grid-side and generator-side inductors, provides a low-impedance path for high-frequency harmonic currents. According to the capacitive reactance formula, the capacitor has very low capacitive reactance for high-frequency signals. Therefore, these high-frequency harmonic currents are short-circuited by the filter capacitor, flowing into the filter capacitor rather than continuing along the main circuit. Therefore, the filter capacitor acts as a "container" that absorbs and stores high-frequency harmonic energy, reducing the flow of harmonics into the grid or load.

[0107] The expression for the resonant frequency of the LCL filter is:

[0108] ;

[0109] in, is the resonant frequency, is the inductance of the grid-side inductor, is the inductance of the machine side inductor, is the capacitance of the filter capacitor, which is also the capacitance value in the LCL filter mentioned above. It can be seen that the resonant frequency and 、 as well as The size of 、 as well as Any of them can reduce the resonant frequency, but it will lead to an increase in cost. Therefore, this application does not change 、 as well as Instead of increasing the size of the signal, a virtual damping signal is introduced to suppress the oscillation, which does not increase the hardware cost.

[0110] In order to capture the high-frequency resonant component in the dq-axis control quantity of the capacitor current, the cutoff frequency of the high-pass filter is set based on the resonant frequency of the LCL filter. The high-pass filter is a filter that allows signals above the cutoff frequency to pass through, while greatly attenuating lower frequencies. Based on this, the high-pass filter can filter out the part of the dq-axis control quantity of the capacitor current that is not greater than the cutoff frequency, that is, not greater than the resonant frequency, while retaining the high-frequency harmonic current in the dq-axis control quantity of the capacitor current that is greater than the resonant frequency, so that high-frequency harmonics can be suppressed subsequently based on the high-frequency harmonic current with a frequency greater than the resonant frequency.

[0111] The transfer function of the high-pass filter is ;

[0112] K is the gain coefficient of the high-pass filter, which determines the gain of the high-frequency signal after passing through the high-pass filter. s is the complex frequency variable. is the cutoff frequency.

[0113] As a preferred embodiment, active damping gain control is performed based on the high-frequency harmonic current in the capacitor current to obtain an active damping gain control output compensation value, including:

[0114] The high-frequency harmonic current in the capacitor current is multiplied by the active damping gain to obtain the active damping gain control output compensation value.

[0115] When performing active damping control on high-frequency harmonic currents, the product of the high-frequency harmonic current and the active damping gain is directly determined as the active damping gain control output compensation value. This can, to a certain extent, reduce reliance on traditional passive filters. Traditional passive filters are typically designed for specific harmonic frequencies, resulting in large size, high cost, and limited filtering effectiveness for harmonics of different frequencies. By multiplying the high-frequency harmonic current by the active damping gain to obtain the active damping gain control output compensation value, software algorithms and control systems can be used to effectively suppress high-frequency harmonics, simplifying the system structure and reducing hardware costs and maintenance difficulties. Furthermore, the active damping gain control output compensation value can be dynamically adjusted based on real-time high-frequency harmonic currents, enabling the system to better adapt to fluctuations in grid voltage and load. That is, regardless of grid conditions, as long as accurate high-frequency harmonic currents are available, the active damping gain can be used to adjust the active damping gain control output compensation value to maintain stable system operation and power quality. This improves the system's adaptability and flexibility, and enhances its ability to cope with different operating conditions and disturbances.

[0116] In summary, the active damping gain control output compensation value, obtained by multiplying the detected high-frequency harmonic current by the active damping gain, can reflect the magnitude and changing trend of the current high-frequency harmonic current in real time. Feeding this value back into the control system can generate a control signal opposite to the high-frequency harmonic current, thereby introducing a voltage component of appropriate magnitude and opposite phase to the high-frequency harmonic current into the power supply voltage, offsetting the voltage drop caused by the high-frequency harmonic current on the grid impedance, effectively suppressing the generation and propagation of high-frequency harmonic current, and improving the quality and stability of the grid voltage. In addition, this compensation method is equivalent to adding an additional damping mechanism to the LCL filter model, which can quickly consume high-frequency harmonic energy, enhance the system's damping characteristics, avoid resonance phenomena that may be caused by insufficient damping of the LCL filter itself, improve the system's stability and dynamic performance, and enable the system to recover to a stable state more quickly when disturbed or subjected to load changes, reducing overshoot and oscillation. Since the active damping gain control output compensation value is calculated directly based on the high-frequency harmonic current, it can accurately track and compensate for the changes in high-frequency harmonics in the power grid. No matter how the frequency, amplitude and phase of the harmonics change, as long as the corresponding high-frequency harmonic current is obtained, the corresponding active damping gain control output compensation value can be generated in time, thereby achieving effective suppression of high-frequency harmonics of different frequencies and amplitudes, and ensuring the waveform quality of the grid voltage and power supply reliability.

[0117] As a preferred embodiment, the primary modulation voltage output by the current loop and the voltage loop is compensated based on the active damping gain control output compensation value to obtain the target modulation voltage, including:

[0118] Compensating the d-axis component of the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control based on the d-axis component in the active damping gain control output compensation value to obtain the d-axis component of the target modulation voltage;

[0119] The q-axis component of the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control is compensated based on the q-axis component in the active damping gain control output compensation value to obtain the q-axis component of the target modulation voltage.

[0120] When compensating the d-axis component of the primary modulation voltage output by the current loop and the voltage loop based on the d-axis component of the active damping gain control output compensation value, and compensating the q-axis component of the primary modulation voltage output by the current loop and the voltage loop based on the q-axis component of the active damping gain control output compensation value, the d-axis component of the target modulation voltage can be determined by adding the d-axis component of the active damping gain control output compensation value and the d-axis component of the primary modulation voltage, and the q-axis component of the target modulation voltage can be determined by adding the q-axis component of the active damping gain control output compensation value and the q-axis component of the primary modulation voltage. Based on this, high-frequency harmonic currents can be detected and extracted from the capacitor current in a timely manner, and corresponding virtual damping signals can be generated through a feedback mechanism to offset these harmonic oscillations, thereby achieving effective suppression of high-frequency harmonics.

[0121] As a preferred embodiment, generating a target modulation signal according to a target modulation voltage to control a rectifier includes:

[0122] Performing coordinate transformation of the d-axis component and the q-axis component of the target modulation voltage to the target modulation voltage in a stationary coordinate system;

[0123] Generate a target modulation signal based on the target modulation voltage in the stationary coordinate system, and control the rectifier based on the target modulation signal

[0124] When generating the target modulation signal, the target modulation voltage in the dq coordinate system must be converted into the target modulation voltage in the stationary coordinate system. After the rectifier is controlled based on the target modulation signal, the high-frequency harmonics on each phase line can be suppressed. Figure 2 , Figure 2 in Based on Convert the target modulation voltage in the dq coordinate system into The target modulation voltage in the coordinate system, SVPWM converts the target modulation voltage into a modulation signal to control the rectifier. Of course, the rectifier can be a PWM rectifier.

[0125] Please refer to Figure 4 and Figure 5 , Figure 4This is a schematic diagram of the current change waveform when no-load is provided in this application. Figure 5 This is a schematic diagram of the current change waveform during loading provided by the present application. It can be seen that regardless of no-load or loading, the control method in this application can effectively suppress high-frequency harmonic currents.

[0126] Please refer to Figure 6 , Figure 6 This is a schematic structural diagram of a rectifier control device provided in this application, the device comprising:

[0127] The acquisition module 61 is configured to acquire a grid voltage reference angle.

[0128] The coordinate transformation module 62 is used to perform coordinate transformation on the capacitor voltage according to the grid voltage reference angle to obtain the dq axis components of the capacitor voltage.

[0129] The differentiation module 63 is used to differentiate the dq-axis components of the capacitor voltage to obtain the dq-axis control quantity of the capacitor current.

[0130] The high-frequency filtering module 64 is used to perform high-frequency filtering on the dq-axis control variables of the capacitor current to obtain high-frequency harmonic current in the capacitor current.

[0131] The active damping module 65 is configured to perform active damping gain control based on the high-frequency harmonic current in the capacitor current to obtain an active damping gain control output compensation value.

[0132] The compensation control module 66 is used to compensate the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control based on the active damping gain control output compensation value to obtain a target modulation voltage, and generate a target modulation signal according to the target modulation voltage to control the rectifier.

[0133] For an introduction to the rectifier control device provided by the present invention, please refer to the above method embodiment, and the present invention will not be described in detail here.

[0134] Please refer to Figure 7 , Figure 7 This is a schematic diagram of the structure of a rectifier control device provided in this application, which includes:

[0135] Memory 71, for storing computer programs;

[0136] The processor 72 is configured to implement the steps of the rectifier control method as described above when executing the computer program.

[0137] For an introduction to the rectifier control device provided by the present invention, please refer to the above method embodiment, and the present invention will not be described in detail here.

[0138] Please refer to Figure 8 , Figure 8This is a schematic diagram of a computer-readable storage medium provided in the present application. A computer program 82 is stored on the computer-readable storage medium 81. When the computer program 82 is executed by the processor 72, the steps of the rectifier control method described above are implemented.

[0139] For an introduction to the computer-readable storage medium provided by the present invention, please refer to the above method embodiment, and the present invention will not go into details here.

[0140] It should also be noted that, in this specification, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus comprising the element.

[0141] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A rectifier control method, characterized in that: include: Get the grid voltage reference angle; Performing coordinate transformation on the capacitor voltage according to the grid voltage reference angle to obtain dq-axis components of the capacitor voltage; performing differential coupling on the dq-axis components of the capacitor voltage to obtain a dq-axis control variable of the capacitor current; Performing high-frequency filtering on the dq-axis control quantity of the capacitor current to obtain a high-frequency harmonic current in the capacitor current; Performing active damping gain control based on the high-frequency harmonic current in the capacitor current to obtain an active damping gain control output compensation value; The primary modulation voltage output by the current loop in the voltage-current dual closed-loop control is compensated based on the active damping gain control output compensation value to obtain a target modulation voltage, and a target modulation signal is generated according to the target modulation voltage to control the rectifier.

2. The rectifier control method according to claim 1, wherein: The obtaining of a grid voltage reference angle includes: The capacitor voltage is phase-locked using a phase-locked loop to obtain the grid voltage reference angle.

3. The rectifier control method according to claim 1, wherein: An LCL filter is provided between the rectifier and the power grid; and differentially coupling the dq-axis components of the capacitor voltage to obtain the dq-axis control quantity of the capacitor current comprises: Differentiate the dq-axis components of the capacitor voltage to obtain the dq-axis components of the capacitor current; The dq axis components of the capacitor current are coupled to obtain the dq axis control quantity of the capacitor current; Among them, the expression of the dq-axis control quantity of the capacitor current is as follows: ； in, is the d-axis control quantity of the capacitor current, is the q-axis control quantity of the capacitor current, is the angular velocity of the dq coordinate system, is the capacitance in the LCL filter, is the d-axis component of the capacitor voltage, is the q-axis component of the capacitor voltage.

4. The rectifier control method according to claim 1, wherein: An LCL filter is provided between the rectifier and the power grid; and the high-frequency filtering of the dq-axis control quantity of the capacitor current to obtain a high-frequency harmonic current in the capacitor current includes: determining a resonant frequency of the LCL filter based on an inductance and a capacitance in the LCL filter; The cutoff frequency of the high-pass filter is set based on the resonant frequency, so that the dq-axis control amount of the capacitor current is subjected to high-frequency filtering by the high-pass filter to obtain a high-frequency harmonic current in the capacitor current.

5. The rectifier control method according to claim 1, wherein: The active damping gain control is performed based on the high-frequency harmonic current in the capacitor current to obtain an active damping gain control output compensation value, including: The high-frequency harmonic current in the capacitor current is multiplied by the active damping gain to obtain an active damping gain control output compensation value.

6. The rectifier control method according to any one of claims 1 to 5, characterized in that: The method of compensating the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control based on the active damping gain control output compensation value to obtain a target modulation voltage includes: Compensating the d-axis component of the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control based on the d-axis component in the active damping gain control output compensation value to obtain the d-axis component of the target modulation voltage; The q-axis component of the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control is compensated based on the q-axis component in the active damping gain control output compensation value to obtain the q-axis component of the target modulation voltage.

7. The rectifier control method according to claim 6, wherein: Generating a target modulation signal according to the target modulation voltage to control the rectifier includes: Performing coordinate transformation of the d-axis component and the q-axis component of the target modulation voltage to a target modulation voltage in a stationary coordinate system; A target modulation signal is generated based on the target modulation voltage in a stationary coordinate system, and the rectifier is controlled based on the target modulation signal.

8. A rectifier control device, characterized in that: The device comprises: An acquisition module is used to obtain a grid voltage reference angle; A coordinate transformation module, configured to perform coordinate transformation on the capacitor voltage according to the grid voltage reference angle to obtain dq-axis components of the capacitor voltage; A differential module, configured to differentiate the dq-axis components of the capacitor voltage to obtain a dq-axis control variable of the capacitor current; A high-frequency filtering module is used to perform high-frequency filtering on the dq-axis control quantity of the capacitor current to obtain high-frequency harmonic current in the capacitor current; an active damping module, configured to perform active damping gain control based on the high-frequency harmonic current in the capacitor current to obtain an active damping gain control output compensation value; The compensation control module is used to compensate the primary modulation voltage output by the current loop in the voltage-current dual closed-loop control based on the active damping gain control output compensation value to obtain a target modulation voltage, and generate a target modulation signal according to the target modulation voltage to control the rectifier.

9. A rectifier control device, characterized in that: include: memory for storing computer programs; A processor, configured to implement the steps of the rectifier control method according to any one of claims 1 to 7 when executing a computer program.

10. A computer-readable storage medium, characterized in that The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the rectifier control method according to any one of claims 1 to 7 are implemented.

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