Enhanced meshing type SVG control method and system for suppressing broadband oscillation

Abstract

The present invention relates to the field of power electronics technology. An embodiment of the present invention provides an enhanced meshed SVG control method and system for suppressing broadband oscillations. The method includes a meshed control process and an additional damping control process. The meshed control process at least includes: generating a virtual internal potential based on a DC voltage and frequency loop, an AC voltage and amplitude loop; generating a three-phase current instruction and a modulation wave based on the virtual internal potential, a virtual impedance and a fast current inner loop; generating and transmitting a converter trigger pulse signal based on the modulation wave; the additional damping control process at least includes: detecting an oscillation frequency point based on a full-band scanning algorithm; extracting the oscillation frequency point and generating an oscillation voltage without phase shift; adjusting the virtual impedance according to the impedance amplitude and phase relationship; and correcting negative damping based on the adjusted virtual impedance.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to an enhanced grid-type SVG control method and system for suppressing broadband oscillation. Background Art

[0002] With the rapid development of renewable energy, especially new energy such as wind power and photovoltaics, the access of new energy stations has put forward higher requirements on the dynamic stability of the power system. However, the grid connection of new energy stations may cause broadband oscillation problems between the power grid and the power grid. This broadband oscillation usually occurs in the frequency band of several Hz to several kHz, and oscillations in different frequency bands have different mechanisms and effects. If not suppressed, broadband oscillations will pose a serious threat to the stability of the power system, causing damage to power equipment at the least, and may cause large-scale disconnection of new energy units from the grid at the worst, and even threaten the safety of the entire power system. Specifically, broadband oscillations will increase the frequency and amplitude of current and voltage fluctuations in the system, thereby affecting the operation of the equipment, and in severe cases may even cause the system to collapse. Especially when unstable new energy such as wind power and photovoltaics are connected more intensively, the weak network characteristics of the power grid are more likely to cause the occurrence and aggravation of oscillation phenomena.

[0003] In order to suppress broadband oscillations, the existing technology usually adopts an oscillation suppression control algorithm, which mainly solves this problem by adjusting the control parameters in the new energy station, adjusting the control strategy, and modifying the control loop of the converter (such as wind turbines and photovoltaic inverters). For example, the existing technology uses the adjustment of the converter control loop to avoid oscillations within a specific frequency range by modifying the control parameters of wind turbines, photovoltaics and other power generation equipment (such as current loop, power loop and voltage loop, etc.). For example, the existing technology uses the addition of damping devices, introduces damping control in the system, adjusts the system impedance, and uses passive and active damping methods to suppress the accumulation of oscillation energy in a specific frequency band. For example, the existing technology uses frequency locking and filtering technology, and uses bandpass filters and frequency-locked loop technology to accurately extract and filter oscillation signals at specific frequencies, so as to eliminate or suppress unstable frequency band oscillations.

[0004] Although the existing technology has adopted a variety of oscillation suppression measures, there are still significant technical limitations and operational difficulties. In other words, the existing technology has the following technical problems: (1) It is difficult to deal with wide-band oscillations: The existing oscillation suppression methods usually rely on control strategies for a single frequency band, while wide-band oscillations involve oscillation problems in multiple frequency bands. The existing technology often finds it difficult to effectively suppress negative damping in a wide frequency band, resulting in poor suppression effect; (2) It is difficult to adjust the control parameters: In new energy sites, the control parameters of wind turbines and photovoltaic inverters are numerous and interrelated. The process of adjusting these parameters often faces the problem of parameter setting difficulties. Overly complex control adjustments may lead to a long system debugging cycle and easily introduce system instability; (3) Poor adaptability to weak grids: The existing control method based on phase-locked loop (PLL) is difficult to ensure the stability of the system in the case of weak grids or large power system fluctuations. This type of method has poor adaptability, especially when the grid frequency and voltage fluctuate greatly. The system responds slowly to disturbances, resulting in the inability to suppress oscillations in a timely manner. (4) Lack of specificity: Most of the current oscillation suppression methods are based on fixed frequencies or preset frequency bands for oscillation control. It is difficult to flexibly adjust the constantly changing oscillation frequency in actual situations, resulting in the effect being not accurate and real-time enough. Summary of the invention

[0005] The present invention provides an enhanced meshing type SVG control method and system for suppressing broadband oscillation, aiming to at least solve the above technical problems.

[0006] Specifically, the embodiment of the present invention provides the following technical solutions:

[0007] In a first aspect, an embodiment of the present invention provides an enhanced meshing type SVG control method for suppressing broadband oscillation, the control method comprising a meshing type control process and an additional damping control process.

[0008] The network control process at least includes:

[0009] Generate virtual internal potential based on DC voltage and frequency loop, AC voltage and amplitude loop;

[0010] Generate three-phase current instructions and modulation waves based on the virtual internal potential, virtual impedance and fast current inner loop;

[0011] Based on the modulation wave, generating and transmitting a converter trigger pulse signal;

[0012] The additional damping control process at least includes:

[0013] Detect and extract the oscillation frequency to generate an oscillating voltage without phase shift;

[0014] adjusting the virtual impedance according to impedance magnitude and phase relationship;

[0015] Based on the adjusted virtual impedance, negative damping is corrected.

[0016] Furthermore, the method further comprises:

[0017] The method of generating a virtual internal potential based on a DC voltage and frequency loop and an AC voltage and amplitude loop comprises:

[0018] The DC voltage and frequency loop generates the frequency and phase angle of the virtual internal potential through the virtual inertia and damping link according to the deviation between the module capacitor voltage and the reference value;

[0019] The AC voltage and amplitude loop generates the amplitude of the virtual internal potential through a proportional-integral link according to the deviation of the AC voltage from a reference value.

[0020] Furthermore, the method further comprises:

[0021] The detecting and extracting the oscillation frequency point to generate an oscillation voltage without phase shift includes:

[0022] The oscillation frequency point is detected based on a full-band scanning algorithm and a fast Fourier transform.

[0023] Furthermore, the method further comprises:

[0024] The detecting and extracting the oscillation frequency point to generate an oscillation voltage without phase shift includes:

[0025] Based on a second-order generalized integrator filter and a frequency-locked loop, the oscillating voltage without phase shift is generated.

[0026] Furthermore, the method further comprises:

[0027] The correcting negative damping based on the adjusted virtual impedance includes:

[0028] Based on the adjusted virtual impedance, a correction current command is generated and superimposed on the three-phase current command.

[0029] In a second aspect, an embodiment of the present invention further provides an enhanced meshing type SVG control system for suppressing broadband oscillation, comprising: the control system comprises a meshing type control module and an additional damping control module,

[0030] The networked control module is configured to at least execute:

[0031] Generate virtual internal potential based on DC voltage and frequency loop, AC voltage and amplitude loop;

[0032] Generate three-phase current instructions and modulation waves based on the virtual internal potential, virtual impedance and fast current inner loop;

[0033] Based on the modulation wave, generating and transmitting a converter trigger pulse signal;

[0034] The additional damping control module is configured to at least perform:

[0035] Detect and extract the oscillation frequency to generate an oscillating voltage without phase shift;

[0036] adjusting the virtual impedance according to impedance magnitude and phase relationship;

[0037] Based on the adjusted virtual impedance, negative damping is corrected.

[0038] Furthermore, the system also includes:

[0039] The networked control module is configured to further perform:

[0040] Based on the DC voltage and frequency loop, according to the deviation of the module capacitor voltage from the reference value, the frequency and phase angle of the virtual internal potential are generated through the virtual inertia and damping link;

[0041] Based on the AC voltage and amplitude loop, the amplitude of the virtual internal potential is generated through a proportional-integral link according to the deviation between the AC voltage and a reference value.

[0042] Furthermore, the system also includes:

[0043] The additional damping control module is configured to further perform:

[0044] The oscillation frequency point is detected based on a full-band scanning algorithm and a fast Fourier transform.

[0045] Furthermore, the system also includes:

[0046] The additional damping control module is configured to further perform:

[0047] Based on a second-order generalized integrator filter and a frequency-locked loop, the oscillating voltage without phase shift is generated.

[0048] Furthermore, the system also includes:

[0049] The additional damping control module is configured to further perform:

[0050] Based on the adjusted virtual impedance, a correction current command is generated and superimposed on the three-phase current command.

[0051] Furthermore, in a third aspect, an embodiment of the present invention also provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned enhanced meshed SVG control method for suppressing broadband oscillations when executing the program.

[0052] Furthermore, in a fourth aspect, an embodiment of the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the steps of the enhanced meshed SVG control method for suppressing broadband oscillations are implemented.

[0053] It can be seen from the above technical solutions that the enhanced meshed SVG control method for suppressing broadband oscillations and the enhanced meshed SVG control system for suppressing broadband oscillations provided in the embodiments of the present invention can at least solve the following problems: (1) It is difficult to cope with broadband oscillations: Existing oscillation suppression methods usually rely on control strategies for a single frequency band, while broadband oscillations involve oscillations in multiple frequency bands. Existing technologies often have difficulty in effectively suppressing negative damping in a wide frequency band, resulting in poor suppression effects; (2) Difficulty in adjusting control parameters: In new energy stations, the control parameters of wind turbines and photovoltaic inverters are numerous and interrelated. In the process of adjusting these parameters, the problem of difficulty in parameter setting is often faced. Overly complex control adjustments may lead to a long system debugging cycle and easily introduce system instability; (3) Poor adaptability to weak networks: Existing control methods based on phase-locked loops (PLLs) are difficult to ensure system stability in the case of weak power grids or large power system fluctuations. This type of method has poor adaptability, especially when the grid frequency and voltage fluctuate greatly. The system responds slowly to disturbances, resulting in the inability to suppress oscillations in a timely manner. (4) Lack of specificity: Most of the current oscillation suppression methods are based on fixed frequencies or preset frequency bands for oscillation control. It is difficult to flexibly adjust the constantly changing oscillation frequency in actual situations, resulting in the effect being not accurate and real-time enough. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1 A flow chart of an enhanced meshing type SVG control method for suppressing broadband oscillation provided by an embodiment of the present invention;

[0056] Figure 2A schematic diagram of an enhanced mesh-type SVG device for suppressing broadband oscillation provided by an embodiment of the present invention;

[0057] Figure 3 A block diagram of a meshed broadband oscillation suppression control based on additional damping in a control method of an enhanced meshed SVG for suppressing broadband oscillation provided by an embodiment of the present invention;

[0058] Figure 4 A schematic diagram of an adaptive oscillation signal extraction in a control method of an enhanced meshed SVG for suppressing broadband oscillation provided by an embodiment of the present invention;

[0059] Figure 5 A schematic diagram of the structure of an enhanced meshed SVG control system for suppressing broadband oscillations provided in one embodiment of the present invention;

[0060] Figure 6 A schematic diagram of an electronic device provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are 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 creative work are within the scope of protection of the present invention.

[0062] The various terms or phrases used in the present invention have the general meanings known to those of ordinary skill in the art. Even so, the present invention still hopes to provide a more detailed description and explanation of these terms or phrases. If the terms and phrases involved in this article are inconsistent with the commonly known meanings, the meanings expressed in the present invention shall prevail; and if not defined in this application, they have the meanings commonly understood by those of ordinary skill in the art.

[0063] The existing technology has many problems including but not limited to the following: (1) it is difficult to cope with wide-band oscillations; (2) it is difficult to adjust control parameters; (3) it has poor adaptability to weak networks; and (4) it lacks specificity.

[0064] In view of this, in a first aspect, an embodiment of the present invention provides an enhanced meshing type SVG control method for suppressing broadband oscillation.

[0065] Combine the following Figure 1 The enhanced meshing type SVG control method for suppressing broadband oscillation of the present invention is described.

[0066] Figure 1The present invention provides a flowchart of an enhanced mesh-type SVG control method for suppressing broadband oscillations according to an embodiment of the present invention.

[0067] In this embodiment, it should be noted that the enhanced meshing type SVG control method for suppressing broadband oscillation may at least include a meshing type control process and an additional damping control process.

[0068] S100: The network control process at least includes: generating a virtual internal potential based on a DC voltage and frequency loop and an AC voltage and amplitude loop; generating a three-phase current command and a modulation wave based on the virtual internal potential, the virtual impedance and the fast current inner loop; generating and transmitting a converter trigger pulse signal based on the modulation wave;

[0069] S200: The additional damping control process at least includes: detecting the oscillation frequency through a full-band scanning algorithm; extracting the oscillation frequency to generate an oscillation voltage without phase shift; adjusting the virtual impedance according to the impedance amplitude and phase relationship; and correcting the negative damping based on the adjusted virtual impedance.

[0070] Specifically, in an embodiment of the present invention, the meshed control process can be designed to simulate the characteristics of a synchronous generator, generate a virtual internal potential through a DC voltage-frequency loop and an AC voltage-amplitude loop, and the virtual internal potential generates a modulation wave through a virtual impedance and a fast current inner loop. The final inverter trigger pulse signal has a wide-band characteristic and can dynamically adjust the system impedance characteristics.

[0071] More specifically, in an embodiment of the present invention, the fast current inner loop ensures that the generated modulation wave accurately responds to the grid demand by quickly feeding back and adjusting the current signal, while realizing efficient control of the dynamic current. The following is a detailed description of the role of the fast current inner loop and its embodiment from three aspects. The first is the dynamic response capability. The fast current inner loop adjusts the output current in real time at a high frequency (usually several thousand hertz) by real-time feedback and adjustment of the output current, suppresses harmonics and current fluctuations, reflects the ability to respond to dynamic demands, and ensures that dynamic changes in the grid can be responded to quickly. The second is to minimize the current error. The fast current inner loop ensures that the output current is consistent with the target current calculated by the virtual impedance through precise error correction, thereby reducing the distortion of the output waveform and making the device more adaptable to weak grid or high dynamic working conditions. The third is to support the generation of modulation waves. The output of the fast current inner loop directly affects the generation quality of the modulation wave and the stability of the grid-side current. Through rapid correction, the signal quality of the modulation wave is ensured, thereby ensuring the dynamic control performance of the equipment. That is to say, in the embodiment of the present invention, the fast current inner loop is the core bridge for converting the virtual internal potential and virtual impedance calculation results into high-quality current output, providing a reliable guarantee for the efficient operation of the entire control method.

[0072] More specifically, in an embodiment of the present invention, the three-phase current instruction, the modulation wave, and the trigger pulse constitute a signal transmission link from the control target to the actual hardware operation. There is a clear hierarchical relationship between them, and the target current generation, signal modulation, and hardware triggering are realized in sequence. Among them, the three-phase current instruction is the result of the calculation of the virtual impedance and the internal potential, which is used to guide the target value of the output current; the modulation wave converts the target current instruction into a voltage instruction signal through a fast current inner loop, providing the basis for pulse width modulation; the trigger pulse discretizes the modulation wave signal, directly acts on the hardware, and controls the switching state of the converter. In other words, the three-phase current instruction embodies the control target, the modulation wave corrects the current error through feedback, and the trigger pulse directly executes the current output behavior. Through this step-by-step transmission and regulation, high-precision dynamic current control is achieved, while further ensuring the real-time and reliability of broadband oscillation suppression and active support capabilities.

[0073] Specifically, in an embodiment of the present invention, the additional damping control process can be designed to start from the oscillation voltage and current signals of the new energy station, and adjust the impedance presented to the outside by the suppression device at the oscillation frequency point according to the amplitude phase relationship between the impedances, so as to correct the negative damping of the new energy station at the oscillation frequency point to positive damping, thereby achieving oscillation suppression. The center frequency of the filter is adaptively adjusted using the frequency-locked loop technology to ensure the accuracy and stability of the oscillation signal extraction.

[0074] More specifically, in an embodiment of the present invention, the additional damping control process obtains the frequency of the oscillation through a full-band scanning algorithm, and then each frequency point is band-pass filtered one by one. The center frequency of the band-pass filter is adaptively adjusted through a frequency-locked loop to ensure that the oscillation frequency voltage signal is extracted without phase shift, thereby accurately adjusting the own impedance. The oscillation frequency is detected by a full-band scanning algorithm, and a second-order generalized integral filter (SOGI) is used to realize the phase-shift-free extraction of the oscillation signal. The system impedance is adjusted based on the impedance amplitude and phase relationship, and the negative damping is corrected to positive damping to suppress oscillation.

[0075] In this embodiment, it should be noted that, for the meshing control process in S100, the enhanced meshing SVG control method for suppressing broadband oscillations may also include: generating a virtual internal potential based on a DC voltage and frequency loop and an AC voltage and amplitude loop, including: the DC voltage and frequency loop generates the frequency and phase angle of the virtual internal potential through a virtual inertia and damping link according to the deviation between the module capacitor voltage and a reference value; the AC voltage and amplitude loop generates the amplitude of the virtual internal potential through a proportional integral link according to the deviation between the AC voltage and the reference value.

[0076] Specifically, in the embodiment of the present invention, the virtual internal potential is the core variable of the grid-type control, which indirectly affects the virtual impedance by controlling the output current and voltage of the system. The key parameters of the virtual internal potential include: frequency, which is generated by the DC voltage-frequency loop, simulates the rotational inertia of the synchronous generator, and affects the dynamic frequency response of the system; phase angle, which represents the instantaneous phase of the virtual internal potential and determines the phase of the output voltage; amplitude, which is generated by the AC voltage-amplitude loop, controls the amplitude of the output voltage, and affects the active and reactive support capabilities of the system.

[0077] In this embodiment, it should be noted that, for S200, the enhanced mesh-type SVG control method for suppressing broadband oscillations may also include: detecting and extracting the oscillation frequency to generate an oscillation voltage without phase shift, including: detecting the oscillation frequency based on a full-band scanning algorithm and a fast Fourier transform.

[0078] In this embodiment, it should be noted that, for S200, the enhanced meshed SVG control method for suppressing broadband oscillations may also include: detecting and extracting the oscillation frequency point to generate an oscillating voltage without phase shift, including: generating an oscillating voltage without phase shift based on a second-order generalized integral filter and a frequency-locked loop.

[0079] Specifically, for S200, in an embodiment of the present invention, the virtual impedance is adjusted according to the impedance amplitude and phase relationship, so as to correct the negative damping to positive damping, which is the core mechanism of the additional damping control. Among them, the amplitude and phase relationship of the impedance determine the dynamic characteristics of the system at a specific frequency. By adjusting these two parameters, the damping characteristics of the system can be effectively changed. At the oscillation frequency, the new energy station may exhibit negative damping characteristics, that is, the phase of the output impedance does not match the current direction (the imaginary part of the impedance is negative), and negative damping will cause the oscillation energy to be amplified and the oscillation gradually loses control. By adjusting the impedance amplitude and phase, the impedance of the system at the oscillation frequency meets the positive damping condition, which plays a role in suppressing oscillation. Among them, the impedance amplitude represents the ratio of the oscillation voltage amplitude to the oscillation current amplitude, and the impedance phase represents the relative relationship between the oscillation voltage and the oscillation current. Adjusting the amplitude and phase can correct the negative damping phenomenon and change the system performance to positive damping. By dynamically adjusting the amplitude and phase, the negative damping of the system can be effectively corrected, the broadband oscillation suppression capability can be enhanced, and the stability of the system can be guaranteed.

[0080] More specifically, in an embodiment of the present invention, the virtual internal potential, which is the core variable of the meshing control, generates a current command through a virtual impedance, providing a basic broadband positive damping characteristic. The additional damping control adjusts the amplitude and phase of the impedance at the oscillation frequency point according to the oscillation voltage and current, changes the damping characteristics of the system, and converts negative damping into positive damping. In other words, in the process of "correcting negative damping to positive damping", the meshing control and additional damping complement each other. The meshing control provides a basic positive damping characteristic, while the additional damping corrects the negative damping for the oscillation frequency point.

[0081] Based on this, in an embodiment of the present invention, by combining a meshing control process and an additional damping control process, the impedance characteristics of the system are dynamically reshaped, and by precise frequency point detection and impedance adjustment, wide-band oscillation suppression is achieved, effectively suppressing broadband oscillations in new energy sites and ensuring the dynamic stability of the power system. In addition, the embodiments of the present invention can also improve the reliability of new energy access, reduce equipment losses, and reduce operational risks. In addition, the embodiments of the present invention can also provide efficient broadband oscillation suppression methods, which will help promote the large-scale application of renewable energy.

[0082] In addition, it should be emphasized that for the combined logical relationship between grid-type control and additional damping control, grid-type control simulates the characteristics of synchronous generators through the generation of virtual internal potential (DC voltage-frequency loop and AC voltage-amplitude loop), realizes active support for the power grid and dynamic impedance characteristic adjustment; while additional damping control corrects negative damping and suppresses broadband oscillations by detecting specific oscillation frequencies and adjusting virtual impedance characteristics in real time. Therefore, the two are coordinated in terms of control objectives. Grid-type control provides the basic impedance model of the system, while additional damping control further optimizes the impedance model to adapt it to the specific needs of broadband oscillations.

[0083] Furthermore, regarding the timing of combining the dynamically adjusted virtual impedance value, the core function of the additional damping control is to dynamically adjust the virtual impedance value. It first detects the oscillation frequency, then calculates the compensation impedance in real time, and finally outputs the dynamically adjusted impedance value in the form of adjusted virtual resistance and virtual reactance. And this adjustment result will be immediately applied to the meshing control process. The meshing control generates the target current command based on the virtual internal potential, and the virtual impedance directly affects the calculation of the current command. When the additional damping control updates the virtual impedance value, the new virtual impedance value will replace the initial value in the meshing control and affect the generation of the target current command. This process is real-time, ensuring that the effect of the additional damping can be quickly transmitted to the current calculation link of the meshing control. Furthermore, through the fast current inner loop, the dynamically adjusted current command is further used to generate a more accurate modulation wave. The optimization of the modulation wave ensures the execution of the additional damping effect, which is finally transmitted to the hardware level through the trigger pulse to form the actual grid-side output. That is to say, after each impedance adjustment, the grid-type control automatically uses the latest virtual impedance value to calculate the target current command. Therefore, the additional damping is linked with the grid-type control, and the dynamic adjustment process runs through the entire operation.

[0084] Figure 2 This is a schematic diagram of an enhanced mesh-type SVG device for suppressing broadband oscillation provided by an embodiment of the present invention.

[0085] like Figure 2 As shown, the hardware framework of grid-type control and additional damping control is embodied, wherein the enhanced grid-type SVG device topology of the enhanced grid-type SVG includes an AC starting circuit, which is composed of an incoming circuit breaker QF1, disconnecting switches QS1 and QE2, a bypass switch QF2, and a starting resistor R, to achieve high-voltage AC access and soft starting of the power valve body. In addition, the enhanced grid-type SVG device of the enhanced grid-type SVG includes a reactor L, one end of the reactor is connected to the grid through the AC starting circuit, and the other end is connected to the power module. The grid-connected reactor connects the grid and the power valve body to filter and limit the fault current.

[0086] Figure 3 A block diagram of a meshed broadband oscillation suppression control based on additional damping in a control method of an enhanced meshed SVG for suppressing broadband oscillation provided by an embodiment of the present invention, and Figure 4 An architecture diagram of adaptive oscillation signal extraction in an enhanced meshed SVG control method for suppressing broadband oscillation provided by an embodiment of the present invention.

[0087] like Figure 3 and Figure 4As shown, the process relationship of virtual internal potential generation, virtual impedance adjustment and oscillation signal extraction is reflected, wherein the electrical signal operation involved in the enhanced mesh type SVG control method for suppressing broadband oscillation is described in more detail.

[0088] Specifically, the virtual internal potential angular velocity ω and phase angle θ are generated based on the DC voltage-frequency loop, as shown in equations (1)-(2).

[0089] (1)

[0090] (2)

[0091] Where s is the differential operator, P m is the active power feedback value, V dcref , V dc are the capacitor voltage command value and actual value respectively, K VCA is the capacitor voltage control proportional coefficient; J , D p are virtual inertia and damping respectively. ω , ω n is the internal potential angular velocity deviation and the rated internal potential angular velocity; θ is the virtual internal potential phase angle.

[0092] Generate virtual internal potential amplitude based on AC voltage-amplitude closed loop E As shown in formula (3).

[0093] (3)

[0094] in V ref , V m are the AC voltage command value and actual value respectively, K pQ and K iQ are the reactive power control integral coefficients, U 1nom is the rated virtual internal potential value.

[0095] The virtual impedance and current limiting control link will be based on the internal potential E And virtual impedance R v , X v The positive and negative sequence current commands of the dq axis are obtained, as shown in equations (5)-(8).

[0096] (4)

[0097] in I dPref , I qPref are the positive sequence d-axis and q-axis current command values ​​respectively, U dp , U qp They are respectively the positive sequence d-axis and q-axis grid-side voltage sampling values, R v , X v are virtual resistance and virtual reactance respectively.

[0098] Generate the positive and negative sequence current DC command I of the dq axis dPref ,I qPref and I dNref ,I qNref After linear transformation, the instantaneous value of the three-phase current command is obtained as shown in formula (5).

[0099] (5)

[0100] in, i aref , i bref , i cref They are three-phase current instructions respectively.

[0101] The additional damping control first obtains the frequency of the oscillation through the full-band scanning algorithm, and then obtains the oscillation component in the grid voltage through the second-order generalized integral (SOGI) filter. The characteristic of the second-order generalized integral filter is that for the center frequency, the phase shift of the filtered signal is zero. The sub-synchronous voltage signal obtained by this extraction method does not need to be phase supplemented, which can ensure that the subsequent links can achieve the goal of parallel pure resistance. The transfer function of SOGI can be expressed as

[0102] (6)

[0103] in, is the input signal of SOGI, and is the output signal of SOGI, is the central angular frequency of SOGI. Assuming the input signal is

[0104] (7)

[0105] According to equations (6) and (7), we can get

[0106] (8)

[0107] in,

[0108] (9)

[0109] According to formula (8), the response time of SOGI is approximately

[0110] (10)

[0111] SOGI's Gains k Determines the frequency bandwidth of SOGI. Very large k A value of 0 will make the SOGI perform faster, reducing its immunity to harmonics in the input signal. Conversely, a small k A large value makes SOGI highly selective in frequency, but results in a long settling time. Therefore, a trade-off needs to be made between settling time, overshoot, and harmonic suppression. The gain of the frequency-locked loop determines the speed of frequency tracking. A very large value will make the frequency tracking faster, but more sensitive to harmonics in the input signal. Conversely, a very small value will reduce the frequency tracking speed, but will be less affected by input harmonics. Based on the detected subsynchronous voltage, a subsynchronous current with the same frequency and phase is output by setting a virtual pure resistance, clamping the broadband oscillation voltage to zero, thereby achieving broadband oscillation suppression.

[0112] After the three-phase current command is superimposed on the current command output by the additional damping control, a three-phase modulation wave is generated through the current inner loop. U aref , U bref , U cref As shown in formula (6).

[0113] (11)

[0114] in, I aref_sso , I bref_sso , I cref_sso is the current command output by the additional damping control, K db is the deadbeat control coefficient, I a , I b , I c is the device current sampling value, U a , U b, U c is the device voltage sampling value; finally, the modulated wave is modulated by carrier phase shift to generate a trigger pulse signal.

[0115] It can be seen from the above technical solutions that an enhanced meshed SVG control method for suppressing broadband oscillations provided in an embodiment of the present invention can at least solve the following problems: (1) It is difficult to cope with broadband oscillations: Existing oscillation suppression methods usually rely on control strategies for a single frequency band, while broadband oscillations involve oscillations in multiple frequency bands. Existing technologies often have difficulty in effectively suppressing negative damping in a wide frequency band, resulting in poor suppression effects; (2) Difficulty in adjusting control parameters: In new energy stations, wind turbines and photovoltaic inverters have numerous and interrelated control parameters. In the process of adjusting these parameters, the problem of difficulty in parameter setting is often faced. Overly complex control adjustments may lead to a long system debugging cycle and easily introduce system instability; (3) Poor adaptability to weak networks: Existing control methods based on phase-locked loops (PLLs) are difficult to ensure system stability in the case of weak power grids or large power system fluctuations. This type of method has poor adaptability, especially when the grid frequency and voltage fluctuate greatly. The system responds slowly to disturbances, resulting in the inability to suppress oscillations in a timely manner. (4) Lack of specificity: Most of the current oscillation suppression methods are based on fixed frequencies or preset frequency bands for oscillation control. It is difficult to flexibly adjust the constantly changing oscillation frequency in actual situations, resulting in the effect being not accurate and real-time enough.

[0116] Based on the same inventive concept, on the other hand, an embodiment of the present invention provides an enhanced meshed SVG control system for suppressing broadband oscillation.

[0117] Combine the following Figure 5 The enhanced meshed SVG control system for suppressing broadband oscillation provided by the present invention is described. The enhanced meshed SVG control system for suppressing broadband oscillation described below and the enhanced meshed SVG control method for suppressing broadband oscillation described above can be referenced to each other.

[0118] Figure 5 A schematic diagram of the structure of an enhanced meshed SVG control system for suppressing broadband oscillations provided in one embodiment of the present invention.

[0119] In the present embodiment, it should be noted that the enhanced meshed SVG control system 100 for suppressing broadband oscillations includes a meshed control module 110 and an additional damping control module 120, and the meshed control module is constructed to at least execute: generating a virtual internal potential based on a DC voltage and frequency loop, an AC voltage and amplitude loop; generating a three-phase current command and a modulation wave based on the virtual internal potential, the virtual impedance and the fast current inner loop; generating and transmitting a converter trigger pulse signal based on the modulation wave; the additional damping control module is constructed to at least execute: detecting and extracting the oscillation frequency point, generating an oscillation voltage without phase shift; adjusting the virtual impedance according to the impedance amplitude and the phase relationship; and correcting the negative damping based on the adjusted virtual impedance.

[0120] In this embodiment, it should be noted that the enhanced meshed SVG control system 100 for suppressing broadband oscillations includes: the meshed control module is constructed to further execute based on the DC voltage and frequency loop, according to the deviation of the module capacitor voltage and the reference value, through the virtual inertia and damping link, to generate the frequency and phase angle of the virtual internal potential; based on the AC voltage and amplitude loop, according to the deviation of the AC voltage and the reference value, through the proportional integral link, to generate the amplitude of the virtual internal potential.

[0121] In this embodiment, it should be noted that the enhanced meshed SVG control system 100 for suppressing broadband oscillations includes: an additional damping control module is constructed to further execute: detecting oscillation frequency points based on a full-band scanning algorithm and a fast Fourier transform.

[0122] In this embodiment, it should be noted that the enhanced meshed SVG control system 100 for suppressing broadband oscillations includes: an additional damping control module is constructed to further execute: generating an oscillating voltage without phase shift based on a second-order generalized integral filter and a frequency-locked loop.

[0123] In this embodiment, it should be noted that the enhanced meshed SVG control system 100 for suppressing broadband oscillations includes: an additional damping control module is constructed to further execute: based on the adjusted virtual impedance, generate a correction current instruction and superimpose the correction current instruction with the three-phase current instruction.

[0124] It can be seen from the above technical solutions that an enhanced meshed SVG control system for suppressing broadband oscillations provided by an embodiment of the present invention can at least solve the following problems: (1) It is difficult to cope with broadband oscillations: Existing oscillation suppression methods usually rely on control strategies for a single frequency band, while broadband oscillations involve oscillations in multiple frequency bands. Existing technologies often have difficulty in effectively suppressing negative damping in a wide frequency band, resulting in poor suppression effects; (2) Difficulty in adjusting control parameters: In new energy stations, wind turbines and photovoltaic inverters have numerous and interrelated control parameters. In the process of adjusting these parameters, the problem of difficulty in parameter setting is often faced. Overly complex control adjustments may lead to a long system debugging cycle and easily introduce system instability; (3) Poor adaptability to weak networks: Existing control methods based on phase-locked loops (PLLs) are difficult to ensure system stability in the case of weak power grids or large power system fluctuations. This type of method has poor adaptability, especially when the grid frequency and voltage fluctuate greatly. The system responds slowly to disturbances, resulting in the inability to suppress oscillations in a timely manner. (4) Lack of specificity: Most of the current oscillation suppression methods are based on fixed frequencies or preset frequency bands for oscillation control. It is difficult to flexibly adjust the constantly changing oscillation frequency in actual situations, resulting in the effect being not accurate and real-time enough.

[0125] Since the enhanced meshed SVG control system for suppressing broadband oscillation provided in the embodiment of the present invention can be used to execute the enhanced meshed SVG control method for suppressing broadband oscillation in the above embodiment, the specific content of its working principle can be found in the introduction of the above method embodiment.

[0126] In this embodiment, it should be noted that the modules in the enhanced meshed SVG control system for suppressing broadband oscillation in the embodiment of the present invention can be integrated into one or deployed separately. The above modules can be combined into one module or further divided into multiple sub-units.

[0127] On the other hand, based on the same inventive concept, another embodiment of the present invention provides an electronic device.

[0128] Figure 6 A schematic diagram of an electronic device provided according to an embodiment of the present invention.

[0129] In this embodiment, it should be noted that the electronic device may include: a processor (processor) 610, a communication interface (Communications Interface) 620, a memory (memory) 630 and a communication bus 640, wherein the processor 610, the communication interface 620, and the memory 630 communicate with each other through the communication bus 640. The processor 610 can call the logic instructions in the memory 630 to execute an enhanced meshed SVG control method for suppressing broadband oscillations. The enhanced meshed SVG control method for suppressing broadband oscillations includes: S100: the meshed control process at least includes: generating a virtual internal potential based on a DC voltage and frequency loop, an AC voltage and amplitude loop; generating a three-phase current instruction and a modulation wave based on the virtual internal potential, the virtual impedance and the fast current inner loop; generating and transmitting a converter trigger pulse signal based on the modulation wave; S200: the additional damping control process at least includes: detecting the oscillation frequency based on a full-band scanning algorithm; extracting the oscillation frequency to generate an oscillation voltage without phase shift; adjusting the virtual impedance according to the impedance amplitude and phase relationship; and correcting the negative damping based on the adjusted virtual impedance.

[0130] In addition, the logic instructions in the above-mentioned memory 630 can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when it is sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0131] On the other hand, the present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, is implemented to execute an enhanced meshed SVG control method for suppressing broadband oscillations, the enhanced meshed SVG control method for suppressing broadband oscillations comprising: S100: the meshed control process at least comprises: generating a virtual internal potential based on a DC voltage and frequency loop, an AC voltage and amplitude loop; generating a three-phase current command and a modulation wave based on the virtual internal potential, the virtual impedance and the fast current inner loop; generating and transmitting a converter trigger pulse signal based on the modulation wave; S200: the additional damping control process at least comprises: detecting the oscillation frequency based on a full-band scanning algorithm; extracting the oscillation frequency to generate an oscillation voltage without phase shift; adjusting the virtual impedance according to the impedance amplitude and the phase relationship; and correcting the negative damping based on the adjusted virtual impedance.

[0132] The system embodiment described above is merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art may understand and implement it without creative work.

[0133] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0134] In addition, in the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0135] In addition, in the present invention, the description with reference to the terms "embodiment", "present embodiment", "another embodiment", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An enhanced meshing type SVG control method for suppressing broadband oscillation, characterized in that: The control method includes a network control process and an additional damping control process. The network control process at least includes: Generate virtual internal potential based on DC voltage and frequency loop, AC voltage and amplitude loop; Generate three-phase current instructions and modulation waves based on the virtual internal potential, virtual impedance and fast current inner loop; Based on the modulation wave, generating and transmitting a converter trigger pulse signal; The additional damping control process at least includes: Detect and extract the oscillation frequency to generate an oscillation voltage without phase shift; adjusting the virtual impedance according to impedance magnitude and phase relationship; Based on the adjusted virtual impedance, negative damping is corrected, The method of generating a virtual internal potential based on a DC voltage and frequency loop and an AC voltage and amplitude loop comprises: The DC voltage and frequency loop generates the frequency and phase angle of the virtual internal potential through the virtual inertia and damping link according to the deviation between the module capacitor voltage and the reference value; The AC voltage and amplitude loop generates the amplitude of the virtual internal potential through a proportional integral link according to the deviation between the AC voltage and the reference value. The detecting and extracting the oscillation frequency point to generate an oscillation voltage without phase shift includes: Based on the full-band scanning algorithm and fast Fourier transform, the oscillation frequency is detected. The grid-forming control process simulates the characteristics of the synchronous generator by generating a virtual internal potential to actively support the power grid and adjust the dynamic impedance characteristics. The additional damping control process detects the oscillation frequency and corrects the negative damping based on the characteristics of the virtual impedance adjusted in real time to suppress broadband oscillations.

2. The enhanced meshing type SVG control method for suppressing broadband oscillation according to claim 1 is characterized in that: The detecting and extracting the oscillation frequency point to generate an oscillation voltage without phase shift includes: Based on a second-order generalized integrator filter and a frequency-locked loop, the oscillating voltage without phase shift is generated.

3. The enhanced meshing type SVG control method for suppressing broadband oscillation according to claim 1, characterized in that: The correcting negative damping based on the adjusted virtual impedance includes: Based on the adjusted virtual impedance, a correction current command is generated and superimposed on the three-phase current command.

4. An enhanced meshing type SVG control system for suppressing broadband oscillation, characterized in that: The control system includes a network control module and an additional damping control module. The networked control module is configured to at least execute: Generate virtual internal potential based on DC voltage and frequency loop, AC voltage and amplitude loop; Generate three-phase current instructions and modulation waves based on the virtual internal potential, virtual impedance and fast current inner loop; Based on the modulation wave, generating and transmitting a converter trigger pulse signal; The additional damping control module is configured to at least perform: Detect and extract the oscillation frequency to generate an oscillating voltage without phase shift; adjusting the virtual impedance according to impedance magnitude and phase relationship; Based on the adjusted virtual impedance, negative damping is corrected, The networked control module is configured to further perform: Based on the DC voltage and frequency loop, according to the deviation of the module capacitor voltage from the reference value, the frequency and phase angle of the virtual internal potential are generated through the virtual inertia and damping link; Based on the AC voltage and amplitude loop, according to the deviation between the AC voltage and the reference value, the amplitude of the virtual internal potential is generated through a proportional integral link, The additional damping control module is configured to further perform: Based on the full-band scanning algorithm and fast Fourier transform, the oscillation frequency is detected. The grid-forming control module simulates the characteristics of the synchronous generator by generating a virtual internal potential to actively support the power grid and adjust the dynamic impedance characteristics. The additional damping control module detects the oscillation frequency and corrects the negative damping based on the characteristics of the virtual impedance adjusted in real time to suppress broadband oscillations.

5. The enhanced meshing type SVG control system for suppressing broadband oscillation according to claim 4 is characterized in that: The additional damping control module is configured to further perform: Based on a second-order generalized integrator filter and a frequency-locked loop, the oscillating voltage without phase shift is generated.

6. The enhanced meshing type SVG control system for suppressing broadband oscillation according to claim 4 is characterized in that: The additional damping control module is configured to further perform: Based on the adjusted virtual impedance, a correction current command is generated and superimposed on the three-phase current command.

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