Network equipment adaptive frequency oscillation damping control method and system

Abstract

This invention belongs to the field of power grid control technology. To address the problem that existing damping configurations become mismatched with new system characteristics when power grid parameters or operating states change, leading to a decrease or even failure in oscillation suppression, this invention proposes a high-frequency oscillation damping control method and system for grid-connected equipment with adaptive oscillation frequency. It identifies the dominant negative damping element in the high-frequency oscillation of the power grid system and constructs an additional damping control system, comprising three parts: a damping gain element, a DC blocking element, and a phase compensation element, which are connected in parallel with the dominant negative damping element. By online identification of the equivalent inductance of the power grid to calculate the system oscillation frequency, and accordingly adjusting the damping gain element parameters of the phase compensation element in real time, adaptive suppression of high-frequency oscillations is achieved.

Description

Technical Field

[0001] This invention belongs to the field of power grid control technology, and in particular relates to a high-frequency oscillation damping control method and system for grid-connected equipment with adaptive oscillation frequency. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] With the large-scale integration of new energy power generation and energy storage devices, the degree of power electronics in the power grid is constantly improving, and the equivalent inertia and damping of the system are significantly decreasing. Grid-connected converters, due to their ability to actively establish voltage and frequency and support the stability of weak power grids and islanded operation, are gradually becoming key grid-connected units in new power systems and are widely used in scenarios such as wind power, photovoltaic and energy storage power stations.

[0004] However, during grid-connected operation, the dynamic interaction between the grid-connected converter and the power grid can induce high-frequency oscillations in the system. Grid-connected converters typically employ multi-level control systems, each with varying bandwidth and dynamic response characteristics. Under actual operating conditions, these control levels are coupled across multiple time scales, making accurate identification of the dominant negative damping element in high-frequency oscillations extremely difficult. Furthermore, the high-frequency oscillation characteristics of grid-connected converter systems are closely related to the power grid's operating mode. Existing oscillation suppression methods often employ additional damping control strategies designed for specific operating conditions. When power grid parameters or operating states change, the original damping configuration may become incompatible with the new system characteristics, leading to a decrease or even failure in oscillation suppression effectiveness. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention provides a method and system for high-frequency oscillation damping control of network construction equipment with adaptive oscillation frequency, thereby achieving adaptive suppression of high-frequency oscillation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a high-frequency oscillation damping control method for network construction equipment with adaptive oscillation frequency, comprising: Identify the dominant negative damping element in the power grid system based on the grid converter and grid impedance model; The input signal, which is the same as the input quantity of the negative damping dominant link of the power grid system, is calculated by the additional damping control link to obtain the compensation signal of the negative damping dominant link of the power grid system. The additional damping control link includes a damping gain link, a DC blocking link, and a phase compensation link. The oscillation frequency of the power grid system is calculated by identifying the equivalent inductance of the power grid online, and the damping gain link parameters of the phase compensation link are adjusted in real time according to the oscillation frequency of the power grid system. High-frequency oscillations are suppressed by using the compensation signal of the negative damping dominant link in the power grid system.

[0007] In a second aspect, the present invention provides a high-frequency oscillation damping control system for network construction equipment with adaptive oscillation frequency, comprising: The negative damping dominant element identification module is configured to: identify the negative damping dominant element of the power grid system based on the grid converter and the power grid impedance model; The damping controller construction and tuning module is configured to: take the input signal, which is the same as the input quantity of the negative damping dominant link of the power grid system, and calculate it through the additional damping control link to obtain the compensation signal of the negative damping dominant link of the power grid system; wherein, the additional damping control link includes a damping gain link, a DC blocking link and a phase compensation link; The damping controller parameter adaptive tuning module is configured to: calculate the oscillation frequency of the power grid system by identifying the equivalent inductance of the power grid online, and adjust the damping gain parameters of the phase compensation stage in real time according to the oscillation frequency of the power grid system. The oscillation suppression module is configured to suppress high-frequency oscillations based on the compensation signal of the negative damping dominant link of the power grid system.

[0008] Thirdly, the present invention provides an electronic device including a memory and a processor, and computer instructions stored in the memory and running on the processor, wherein the computer instructions, when executed by the processor, perform the method described in the first aspect.

[0009] Fourthly, the present invention provides a computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in the first aspect.

[0010] Fifthly, the present invention provides a computer program product, including a computer program that, when executed by a processor, implements the method described in the first aspect.

[0011] The above one or more technical solutions have the following beneficial effects: In this invention, the dominant negative damping element of high-frequency oscillation in the power grid system is identified, and an additional damping control is constructed to obtain the compensation signal of the dominant negative damping element. The additional damping control element consists of three parts: a damping gain element, a DC blocking element, and a phase compensation element. The additional damping control element is connected in parallel with the dominant negative damping element. The system oscillation frequency is calculated by online identification of the equivalent inductance of the power grid, and the damping gain element parameters of the phase compensation element are adjusted in real time accordingly to achieve adaptive suppression of high-frequency oscillation.

[0012] In this invention, the compensation angle of the phase compensator is opposite to the phase of the original control loop at the resonant frequency, ensuring that the signal of the additional control loop can cancel the oscillation signal in the original control loop; the gain of the additional damping control loop is satisfied to be the same as the gain of the original control loop at the oscillation frequency, so that the damping signal can cancel the oscillation signal in the dominant negative damping dominant loop.

[0013] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0014] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0015] Figure 1 This is a block diagram of the additional damping control of the network construction device in an embodiment of the present invention; Figure 2 This is a flowchart of the steps of the high-frequency oscillation damping control method and system for network construction equipment in this embodiment of the invention; Figure 3 This is a schematic diagram of the high-frequency oscillation damping control system of the network construction equipment in an embodiment of the present invention. Detailed Implementation

[0016] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0017] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0018] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0019] Example 1 This embodiment discloses a high-frequency oscillation damping control method for network construction equipment with adaptive oscillation frequency, including: Identify the dominant negative damping element in the power grid system based on the grid converter and grid impedance model; The input signal, which is the same as the input quantity of the negative damping dominant link of the power grid system, is calculated by the additional damping control link to obtain the compensation signal of the negative damping dominant link of the power grid system. The additional damping control link includes a damping gain link, a DC blocking link, and a phase compensation link. The oscillation frequency of the power grid system is calculated by identifying the equivalent inductance of the power grid online, and the damping gain link parameters of the phase compensation link are adjusted in real time according to the oscillation frequency of the power grid system. High-frequency oscillations are suppressed by using the compensation signal of the negative damping dominant link in the power grid system.

[0020] This embodiment identifies the dominant negative damping element of high-frequency oscillations in the power grid system and constructs an additional damping control, which includes three parts: a damping gain element, a DC blocking element, and a phase compensation element. These are connected in parallel with the dominant negative damping element. Finally, by identifying the equivalent inductance of the power grid online and calculating the system oscillation frequency, the damping control parameters can be adaptively adjusted according to the actual operating conditions. This allows the grid-connected converter to dynamically adjust the control strategy according to changes in power grid parameters and operating status, thereby providing excellent stability and oscillation suppression under different power grid conditions.

[0021] The adaptive oscillation frequency-based high-frequency oscillation damping control method for grid-connected equipment proposed in this embodiment accurately identifies the negative damping element of the system's high-frequency oscillation based on the relationship between the control loop gain and the real part of the output impedance of the grid-connected converter. This helps to compensate for it in a targeted manner, improving the oscillation suppression effect and avoiding the problem of unstable effect when compensation is applied to non-dominant elements when the dominant element changes. In addition, the phase compensator and damping gain are tuned in real time accordingly, so that the compensation simultaneously satisfies the phase cancellation and gain matching conditions at the oscillation frequency. Therefore, it can still maintain effective oscillation suppression when the oscillation frequency drifts due to changes in grid parameters, avoiding problems such as frequency shift, parameter mismatch, decreased oscillation suppression capability, or even failure.

[0022] The following is combined Figure 2 The high-frequency oscillation damping control method for network construction equipment with adaptive oscillation frequency proposed in this embodiment is described in detail below: Step 1: Identify the dominant negative damping element in the system based on the converter and grid impedance models.

[0023] (1) Determine the system oscillation frequency.

[0024] In a grid-connected converter system, the output impedance of the grid-connected converter and the grid impedance can be expressed as: (1) In the formula, Z GFM ( s Z represents the output impedance of the grid converter. g ( s () represents the power grid impedance; s For the frequency in the complex domain, s =j oh ,in oh ω is the angular frequency, and j is the imaginary unit.

[0025] When the output impedance of the grid converter is equal to the amplitude of the grid impedance, the corresponding angular frequency is the system oscillation frequency, i.e.: (2) In the formula, oh m This represents the system oscillation frequency.

[0026] (2) Criteria for negative damping control loop of grid converter.

[0027] At the oscillation frequency point oh m At a certain point, the equivalent real part of the output impedance of the grid converter is related to a certain control element of the system. G v ( s The function of loop gain: (3) In the formula, R GFM The real part of the output impedance of the grid converter; G v This is for the control loop of the grid converter.

[0028] At oscillation frequency oh m If the control links are improved G v The loop gain leads to a significant reduction in the real part of the grid converter impedance, which can be considered as the control loop. G v At oscillation frequency oh m The following is the dominant element of the system's negative damping.

[0029] The negative damping criterion for the control loop can be expressed as: (4) In the formula, s 0 represents the preset sensitivity threshold. s 0<0; Z GFM ( s ) represents the output impedance of the grid converter; j is the imaginary unit; oh m The oscillation frequency; G v This is for the control loop of the grid converter.

[0030] Step 2: Construct an additional damping control structure and design the corresponding damping gain element, DC blocking element, and phase compensation element structure.

[0031] Additional control structures such as Figure 1 As shown, the input signal of this control strategy is the same as the input of the negative damping dominant link. After calculation by the damping gain link, DC blocking link and phase compensation link, the compensation signal is introduced into the negative damping dominant link to suppress high-frequency oscillation.

[0032] (1) Damping gain stage.

[0033] The damping gain stage amplifies the input signal by adjusting the damping gain. k D To provide sufficient damping for the high-frequency components in the negative damping-dominated stage of the grid-type converter, its transfer function It can be represented as: (6) (2) Isolation link.

[0034] To avoid the additional control loop disrupting the steady-state characteristics of the original control loop, it is necessary to filter out the DC signal in the additional control, retaining only the oscillating component, and adjust the transfer function of the DC blocking loop. It can be represented as: (7) In the formula, T 1 represents the time constant of the DC blocking element, and its value is generally between 0.001s and 0.01s.

[0035] (3) Phase compensation stage.

[0036] The phase of the high-frequency oscillation component in the dominant negative damping element is related to its control structure. To ensure that the oscillation damping signal is out of phase with the dominant element, a phase compensation element should be added, whose transfer function... It can be represented as: (8) In the formula, T 2. Phase lead time constant; T 3 represents the phase lag time constant.

[0037] In summary, the transfer function of the additional damping control element G d (s) can be expressed as: (9) in, T 1 represents the time constant of the DC blocking element; T 2. Phase lead time constant; T 3 represents the phase lag time constant.

[0038] The oscillation compensation signal output by the additional damping control circuit can then be expressed as: (10) In the formula, Δ y This is the oscillation compensation signal for the additional damping control circuit; y in This is the output signal of the oscillation-dominant element.

[0039] Step 3: Obtain the equivalent inductance of the power grid online.

[0040] Step 4: Calculate the system oscillation frequency based on the LCL circuit resonant frequency.

[0041] The high-frequency oscillation frequency of a grid-connected converter system is determined by the resonant frequency of the LCL circuit composed of the filter capacitor and the grid inductance. Therefore, the equivalent grid inductance can be obtained either from the upstream grid dispatch center or by the converter itself using the fundamental impedance identification method. L g According to the equivalent inductance of the power grid L g Calculate the resonant frequency of the LCL circuit: (11) In the formula, L f For converter filter inductance; C f For converter filter capacitors; L g This is the equivalent inductance of the power grid.

[0042] Step 5: Adaptively adjust the parameters of the phase compensation stage in the additional control based on the phase of the dominant element at the oscillation frequency.

[0043] To ensure that the additional control signal can cancel the oscillation signal in the original control loop, the compensation angle of the phase compensator should be at the resonant frequency. oh r Down with the original control link G v The phases of (s) are opposite, that is: (12) In the formula, f This is the phase compensation angle.

[0044] The center frequency of the phase compensator is set to the oscillation frequency, and the phase compensation angle is set to... f The phase compensator parameters can then be adjusted in real time according to the following formula: (13) In the formula, α , T s These are intermediate variables used in the calculation process of the phase compensator.

[0045] Step 6: Adaptively adjust the parameters of the damping gain element in the additional control based on the gain of the dominant element at the oscillation frequency.

[0046] The gain of the additional damping control element should be the same as that of the original control element at the oscillation frequency, so that the damping signal can cancel the oscillation signal in the dominant negative damping control element.

[0047] The gain of the additional damping control circuit can be tuned in real time according to the following formula: (14) This embodiment first identifies the dominant negative damping element for high-frequency oscillations based on the relationship between the control loop gain of the grid converter and the real part of its output impedance. Second, it constructs an additional damping control system, comprising a damping gain element, a DC blocking element, and a phase compensation element, which are connected in parallel with the dominant negative damping element. Finally, by identifying the equivalent inductance of the grid online, the system oscillation frequency is calculated, and the parameters of the damping gain element in the phase compensation element are adjusted in real time to achieve adaptive suppression of high-frequency oscillations.

[0048] Example 2 The purpose of this embodiment is to provide a high-frequency oscillation damping control system for network construction equipment with adaptive oscillation frequency, including: The negative damping dominant element identification module is configured to: identify the negative damping dominant element of the power grid system based on the grid converter and the power grid impedance model; The damping controller construction module is configured to: take the input signal, which is the same as the input quantity of the negative damping dominant link of the power grid system, and calculate it through the additional damping control link to obtain the compensation signal of the negative damping dominant link of the power grid system; wherein, the additional damping control link includes a damping gain link, a DC blocking link, and a phase compensation link; The damping controller parameter adaptive tuning module is configured to: calculate the oscillation frequency of the power grid system by identifying the equivalent inductance of the power grid online, and adjust the damping gain parameters of the phase compensation stage in real time according to the oscillation frequency of the power grid system. The oscillation suppression module is configured to suppress high-frequency oscillations based on the compensation signal of the negative damping dominant link of the power grid system.

[0049] In further embodiments, the following is also provided: An electronic device includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor. When executed by the processor, the computer instructions perform the method described in Embodiment 1. For brevity, further details are omitted here.

[0050] It should be understood that in this embodiment, the processor can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor, etc.

[0051] Memory may include read-only memory and random access memory, and provides instructions and data to the processor. A portion of memory may also include non-volatile random access memory. For example, memory may also store information about the device type.

[0052] A computer-readable storage medium for storing computer instructions, which, when executed by a processor, perform the method described in Embodiment 1.

[0053] The method in Embodiment 1 can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor. The software modules can reside in readily available storage media in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. This storage medium is located in memory; the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method. To avoid repetition, a detailed description is not provided here.

[0054] Those skilled in the art will recognize that the units and algorithm steps described in conjunction with the embodiments herein can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0055] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A high-frequency oscillation damping control method for network construction equipment with adaptive oscillation frequency, characterized in that, include: Identify the dominant negative damping element in the power grid system based on the grid converter and grid impedance model; The input signal, which is the same as the input quantity of the negative damping dominant link of the power grid system, is calculated by the additional damping control link to obtain the compensation signal of the negative damping dominant link of the power grid system. The additional damping control link includes a damping gain link, a DC blocking link, and a phase compensation link. The oscillation frequency of the power grid system is calculated by identifying the equivalent inductance of the power grid online, and the damping gain link parameters of the phase compensation link are adjusted in real time according to the oscillation frequency of the power grid system. High-frequency oscillations are suppressed by using the compensation signal of the negative damping dominant link in the power grid system.

2. The high-frequency oscillation damping control method for network construction equipment with adaptive oscillation frequency as described in claim 1, characterized in that, When the output impedance of the grid converter is equal to the amplitude of the grid impedance, the corresponding angular frequency is the oscillation frequency of the grid system.

3. The high-frequency oscillation damping control method for network construction equipment with adaptive oscillation frequency as described in claim 1, characterized in that, The oscillation frequency of the power grid system is calculated by identifying the equivalent inductance of the power grid online, and the damping gain parameters of the phase compensation stage are adjusted in real time based on the oscillation frequency of the power grid system. Specifically: The oscillation frequency of the power grid system is calculated by identifying the equivalent inductance of the power grid online. The phase compensation angle is determined based on the fact that the compensation angle of the phase compensator is opposite to the phase of the original grid converter control loop at the resonant frequency. The center frequency of the phase compensator is set as the oscillation frequency, and the parameters of the phase compensator are adjusted in real time based on the determined phase compensation angle.

4. The high-frequency oscillation damping control method for network construction equipment with adaptive oscillation frequency as described in claim 1 or 3, characterized in that, The damping gain parameters of the phase compensation stage are adjusted in real time based on the oscillation frequency of the power grid system, specifically as follows: in, α , φ is an intermediate variable in the calculation process of the phase compensator; φ is the phase compensation angle. The resonant frequency; T 2. Phase lead time constant; T 3 represents the phase lag time constant.

5. The high-frequency oscillation damping control method for network construction equipment with adaptive oscillation frequency as described in claim 1, characterized in that, Also includes: Based on the fact that the gain of the additional damping control element satisfies the requirement that it be the same as the gain of the original grid converter control element at the oscillation frequency, the parameters of the damping gain element are determined.

6. The high-frequency oscillation damping control method for network construction equipment with adaptive oscillation frequency as described in claim 1, characterized in that, The grid converter control circuit is the dominant negative damping circuit at the grid system frequency.

7. The high-frequency oscillation damping control method for network construction equipment with adaptive oscillation frequency as described in claim 1, characterized in that, The transfer function of the additional damping control element is expressed as: ； in, k D To adjust the damping gain; T 2. Phase lead time constant; T 3 is the phase lag time constant; T1 is the DC blocking time constant; , , These are the transfer functions for the damping gain element, the DC blocking element, and the phase compensation element, respectively.

8. A high-frequency oscillation damping control system for network construction equipment with adaptive oscillation frequency, characterized in that, include: The negative damping dominant element identification module is configured to: identify the negative damping dominant element of the power grid system based on the grid converter and the power grid impedance model; The damping controller construction and tuning module is configured to: take the input signal, which is the same as the input quantity of the negative damping dominant link of the power grid system, and calculate it through the additional damping control link to obtain the compensation signal of the negative damping dominant link of the power grid system; wherein, the additional damping control link includes a damping gain link, a DC blocking link and a phase compensation link; The damping controller parameter adaptive tuning module is configured to: calculate the oscillation frequency of the power grid system by identifying the equivalent inductance of the power grid online, and adjust the damping gain parameters of the phase compensation stage in real time according to the oscillation frequency of the power grid system. The oscillation suppression module is configured to suppress high-frequency oscillations based on the compensation signal of the negative damping dominant link of the power grid system.

9. An electronic device, characterized in that, It includes a memory and a processor, as well as computer instructions stored in the memory and running on the processor, which, when executed by the processor, perform the method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, Used to store computer instructions, which, when executed by a processor, perform the method described in any one of claims 1-7.

Images