Power oscillation suppression method and device of converter, electronic equipment and storage medium

Abstract

The invention discloses a method and a device for suppressing power oscillation of a converter, electronic equipment and a storage medium, which are used for solving the technical problems of low damping efficiency, limited applicability and insufficient system robustness in the prior art. The invention discloses a power oscillation suppression system applied to a converter. The power oscillation suppression system comprises a main control loop and a cooperative damping controller, firstly, a power reference value and a frequency oscillation signal are output through a main control loop; according to the power reference value and the frequency oscillation signal, power adjustment based on active-reactive damping cooperative control is carried out through a cooperative damping controller, and a power adjustment instruction value is generated; and finally, adjusting the power output of the converter through the main control loop based on the power adjustment instruction value.

Description

Technical Field

[0001] This invention relates to the field of converter power control technology, and in particular to a method, apparatus, electronic device, and storage medium for suppressing power oscillations in converters. Background Technology

[0002] Currently, renewable energy sources, represented by wind and solar power, are being integrated into modern power systems on an unprecedented scale. The grid connection of these new energy sources generally relies on advanced power electronic converter technology. However, traditional converters mostly employ grid-following control strategies. Their operation is highly dependent on the stable voltage and frequency support provided by the grid, and they lack the ability to actively construct their own grid. With the large-scale integration of such converters and their gradual replacement of traditional synchronous generator sets, the overall dynamic characteristics of the power system have undergone fundamental changes. This is mainly reflected in a significant decrease in the system's equivalent moment of inertia and inherent damping level. This change weakens the "strength" of the grid. When subjected to external disturbances, the stability margin of the system's frequency and voltage decreases, making it highly susceptible to low-frequency power oscillations on transmission lines. These oscillations not only limit power transmission capacity but, in severe cases, can threaten the safe and stable operation of the entire system.

[0003] To address this significant challenge, grid-forming control (GFM) technology has emerged and is considered a key technology supporting future high-proportion renewable energy power systems. Through its unique control strategy, the grid-forming converter presents itself as a controllable ideal voltage source, capable of independently or collaboratively establishing stable voltage and frequency for the power grid. Virtual synchronous generator (FSG) technology, as the mainstream implementation of grid-forming control, accurately simulates the mechanical swing equations and electromagnetic transient characteristics of traditional synchronous generators in software algorithms, enabling the converter to provide controllable virtual inertia and damping support to the grid. However, while simulating the excellent characteristics of synchronous machines, grid-forming converters also inherit their inherent electromechanical oscillation problems. Especially in weak grid scenarios connected to the main grid via high-impedance lines, the complex dynamic interaction between its control system and the grid makes the converter's power oscillation mode prone to exhibiting weak damping characteristics. Therefore, developing an additional control technology that can significantly enhance the damping characteristics of the grid-forming converter has become a core technical challenge that must be solved to ensure its safe and efficient application.

[0004] Currently, power oscillations are primarily suppressed through controllers. Examples include the Power System Stabilizer (PSS) for traditional synchronous generators and the Power Oscillation Damper (POD) for converters. However, these single-dimensional damping control schemes have significant limitations in addressing grid-connected converter oscillations due to their inherent constraints. These limitations primarily manifest as low damping efficiency, limited applicability, and insufficient system robustness. Furthermore, employing current mainstream technologies also leads to high operating costs, economic conflicts, and underutilization of equipment potential. Summary of the Invention

[0005] This invention provides a method, apparatus, electronic device, and storage medium for suppressing power oscillations in a converter, which solves or partially solves the technical problems of low damping efficiency, limited applicability, and insufficient system robustness in current related technologies.

[0006] This invention provides a power oscillation suppression method for a converter, applied to a power oscillation suppression system for a converter, wherein the power oscillation suppression system includes a main control loop and a cooperative damping controller; the method includes:

[0007] The main control circuit outputs a power reference value and a frequency oscillation signal.

[0008] Based on the power reference value and the frequency oscillation signal, the power regulation is performed by the cooperative damping controller based on active and reactive power damping cooperative control, and a power regulation command value is generated.

[0009] Based on the power adjustment command value, the power output of the converter is adjusted through the main control loop.

[0010] Optionally, the coordinated damping controller includes a washing-out stage, a damping gain stage, and a superposition module connected in series; the step of generating a power adjustment command value by performing power regulation based on active and reactive power damping coordinated control through the coordinated damping controller according to the power reference value and the frequency oscillation signal includes:

[0011] The frequency oscillation signal is filtered through the washing process to obtain the adjusted signal.

[0012] The adjusted signal is input to the damping gain stage for gain adjustment to generate a power modulation signal;

[0013] Based on the power modulation signal and the power reference value, the power adjustment command value is obtained by superimposing the reference value through the superposition module.

[0014] Optionally, the damping gain stage includes a parallel and independently controlled active power damping gain stage and a reactive power damping gain stage; the step of inputting the adjusted signal into the damping gain stage for gain adjustment to generate a power modulation signal includes:

[0015] The adjusted signal is input to the active power damping gain stage for active power gain adjustment to generate an active power modulation signal.

[0016] The adjusted signal is input to the reactive power damping gain stage for reactive power gain adjustment, thereby generating a reactive power modulation signal.

[0017] Optionally, the power reference value includes an active power reference value and a reactive power reference value; the power modulation signal includes an active power modulation signal and a reactive power modulation signal; the superposition module includes a subtraction module and an addition module; the step of obtaining a power adjustment command value by superimposing reference values ​​based on the power modulation signal and the power reference value through the superposition module includes:

[0018] Based on the active power reference value and the active power modulation signal, the active power adjustment command value is obtained by subtracting the reference value through the subtraction module.

[0019] Based on the reactive power reference value and the reactive power modulation signal, the reactive power adjustment command value is obtained by performing reference value addition calculation through the addition module.

[0020] Optionally, a phase-shifting stage composed of a lead-lag network is added between the washing stage and the damping gain stage; the phase-shifting stage is used to perform phase compensation for oscillations in a preset frequency band.

[0021] Optionally, the damping gain element is a linear gain element, or a nonlinear gain element that is related to the amplitude of the adjusted signal.

[0022] Optionally, the power regulation command value includes an active power regulation command value and a reactive power regulation command value; the main control loop includes a virtual synchronous machine and inner and outer loop controllers; the step of regulating the power output of the converter through the main control loop based on the power regulation command value includes:

[0023] Obtain the actual measured values ​​of active power and reactive power;

[0024] Based on the active power adjustment command value and the actual measured active power value, the output voltage phase angle of the converter is generated through the virtual synchronization control of the virtual synchronizing machine.

[0025] The reactive power adjustment command value is input to the inner and outer loop controllers. Based on the reactive power adjustment command value and the actual measured reactive power value, the voltage reference value is adjusted by droop control.

[0026] Based on the voltage reference value, the output voltage of the converter is generated through the voltage outer loop and current inner loop control of the inner and outer loop controllers;

[0027] Based on the output voltage phase angle and the output voltage, a power control signal is generated by combining coordinate transformation and PWM pulse width modulation, so as to adjust the power output of the converter based on the power control signal.

[0028] This invention also provides a power oscillation suppression device for a converter, applied to a power oscillation suppression system of a converter, wherein the power oscillation suppression system includes a main control loop and a cooperative damping controller; the device includes:

[0029] The data output unit is used to output a power reference value and a frequency oscillation signal through the main control circuit;

[0030] The power regulation unit is used to perform power regulation based on active and reactive power damping coordinated control through the coordinated damping controller according to the power reference value and the frequency oscillation signal, and generate a power regulation command value.

[0031] A power output control unit is used to adjust the power output of the converter through the main control loop based on the power adjustment command value.

[0032] The present invention also provides an electronic device, the device comprising a processor and a memory:

[0033] The memory is used to store program code and transmit the program code to the processor;

[0034] The processor is configured to execute the power oscillation suppression method for the converter as described in any of the preceding embodiments, according to instructions in the program code.

[0035] The present invention also provides a computer-readable storage medium for storing program code for performing the power oscillation suppression method for a converter as described in any of the preceding claims.

[0036] As can be seen from the above technical solutions, the present invention has the following advantages:

[0037] A method for suppressing power oscillations in a converter is provided. The power oscillation suppression system applied to the converter includes a main control loop and a cooperative damping controller. First, the main control loop outputs a power reference value and a frequency oscillation signal. Then, based on the power reference value and the frequency oscillation signal, the cooperative damping controller performs power regulation based on active and reactive power damping coordinated control, generating a power regulation command value. Finally, based on the power regulation command value, the main control loop regulates the converter's power output. By configuring and cooperating the active and reactive power damping channels in parallel, the complementary advantages of the two control resources can be fully utilized, achieving a more powerful and efficient oscillation suppression effect than any single damping method, fundamentally solving the problem of low efficiency in single-dimensional control. Simultaneously, utilizing the synergistic effect of active and reactive power damping mechanisms can improve the adaptability of the control strategy to different power grid conditions and enhance the overall robustness of the system. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 A schematic diagram of a single-unit infinite bus system for a grid-type converter.

[0040] Figure 2 This is a schematic diagram of a power oscillation suppression system for a converter.

[0041] Figure 3 A flowchart illustrating the steps of a power oscillation suppression method for a converter;

[0042] Figure 4 This is a schematic diagram of the overall process for a power oscillation suppression method for a converter.

[0043] Figure 5 Figures showing the eigenvalue analysis results under different damping control scenarios;

[0044] Figure 6 The active power transient response curves are shown under different damping control strategies.

[0045] Figure 7 This is a structural block diagram of a power oscillation suppression device for a converter. Detailed Implementation

[0046] This invention provides a method, apparatus, electronic device, and storage medium for suppressing power oscillations in a converter, which solves or partially solves the technical problems of low damping efficiency, limited applicability, and insufficient system robustness in current related technologies.

[0047] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0048] To enable those skilled in the art to better understand the technical solutions provided in the embodiments of the present invention, some of the technical features involved in the solutions are briefly described first:

[0049] Virtual Synchronous Generator (VSG): A mainstream implementation of grid-connected converters (GFM), which controls the converter by simulating the physical equations of a synchronous generator.

[0050] Washout Filter: A high-pass filter used to block DC and low-frequency signals while allowing dynamic signals to pass through.

[0051] Damping ratio (ζ): A key indicator for measuring how quickly oscillations decay. The higher the value, the faster the decay and the more stable the system.

[0052] As an example, current methods primarily suppress power oscillations through controllers. In traditional power systems dominated by synchronous generators, power system stabilizers (PSS) are typically installed in the excitation system of the synchronous generators to suppress low-frequency oscillations caused by disturbances between units. PSS technology is mature and widely used in traditional power grids, but its design is tailored to the physical characteristics of synchronous generators and cannot be directly applied to power electronic converters. With the development of grid-connected converter technology, engineers have adopted the concept of PSS and begun designing dedicated power oscillation dampers (PODs) for converters. However, these single-dimensional damping control schemes have significant limitations in addressing grid-connected converter oscillation problems due to their inherent constraints. A detailed analysis follows:

[0053] I. Low damping efficiency and limited applicability

[0054] The mechanism of using reactive power damping alone is to indirectly affect the system power angle by adjusting the voltage. This control link is relatively long and its effectiveness is highly dependent on the strength of the power grid. Simulation results clearly show that in scenarios with weak grid connections, reactive power damping alone has a negligible effect on improving the system damping ratio and cannot effectively suppress power oscillations.

[0055] II. Insufficient System Robustness

[0056] Because it utilizes only a single control dimension, the current scheme is quite sensitive to changes in system operating conditions. When the equivalent impedance of the power grid or its operating mode changes, the previously tuned set of fixed controller parameters may no longer be applicable, and its control effect will be significantly reduced. Under certain severe operating conditions, negative damping may even occur due to phase mismatch, which could exacerbate system oscillations.

[0057] Third, high operating costs and economic conflicts exist.

[0058] While using active power damping alone offers a more direct control effect, it requires frequent and significant adjustments to the converter's active power. This adjustment directly interferes with the maximum power tracking (MPT) operation of the renewable energy generation units, causing energy loss that could otherwise be captured. Simultaneously, the adjustments also subject the associated energy storage system to frequent power surges, accelerating its aging and shortening its lifespan. Therefore, this approach essentially sacrifices system operational economy for increased stability.

[0059] IV. The potential of the equipment has not been fully explored.

[0060] Traditional approaches separate active and reactive power control resources, failing to recognize their complementarity in physical properties and operational mechanisms. This non-cooperative approach fails to fully exploit the potential of grid-connected converters as advanced, multi-degree-of-freedom power electronic devices in suppressing system oscillations.

[0061] Therefore, one of the core inventive points of this invention is to provide a novel active-reactive power synergistic damping control system and method for power oscillations. By proposing an innovative integrated synergistic damping control strategy, the active power damping channel and the reactive power damping channel are configured in parallel and work collaboratively, and this strategy is integrated into the control system of a single grid-type converter. This fully utilizes the complementary advantages of the two control resources, achieving a more powerful and efficient oscillation suppression effect than any single damping method, fundamentally solving the problem of low efficiency in single-dimensional control. Simultaneously, the flexible configuration of the gains of the two independent active and reactive power channels allows technicians to flexibly balance the system's damping performance and operating economic costs according to actual needs, effectively resolving the inherent contradiction between stability and economy. Utilizing the synergistic effect of the active and reactive power damping mechanisms can improve the adaptability of the control strategy to different power grid conditions and enhance the overall robustness of the system.

[0062] In practical applications, the technical solution of this invention is particularly suitable for scenarios where a single grid-connected converter is connected to an external large power grid and an infinite bus via transmission lines. For example, a voltage source converter (VSC) is used as an example. Figure 1 A schematic diagram of a grid-connected converter single-unit infinite bus system is shown. This scenario serves as a typical system model for studying and verifying the grid-connected dynamic characteristics of power electronic equipment.

[0063] Specifically, Figure 1 A schematic diagram is shown illustrating the connection of a voltage source converter (VSC) to the power grid via an LCL-type filter (an LCL-type filter topology consisting of two inductors L and one capacitor C). Figure 1 middle, This refers to the grid voltage. This refers to the voltage at the grid connection point. and These represent the output inductance and resistance of the voltage source converter and the line, respectively. Indicates the current flowing through; and This indicates the active and reactive power output of the voltage source converter to the power grid.

[0064] The power oscillation suppression control system provided in this embodiment of the invention is based on the main control loop of a grid-type converter, with an additional cooperative damping controller (additional damping control module). The internal structure, signal flow, and connection relationship with the main control loop of the cooperative damping controller are the core of realizing the technical solution of this invention.

[0065] Reference Figure 2The diagram shows a schematic of the power oscillation suppression system for a converter provided in an embodiment of the present invention.

[0066] Combination Figure 2 The power oscillation suppression system of the converter mainly consists of the following two modules:

[0067] Grid-type main control module: also known as the main control loop. This module forms the basis of the converter's power oscillation suppression system, aiming to enable the voltage source converter to simulate the external characteristics of a synchronous generator, thereby achieving grid-type control. The entire control strategy of the main control loop can be divided into virtual synchronous machine (VSG) control and inner and outer loop control.

[0068] Among them, the Virtual Synchronous Generator (VSG) simulates the rotor motion equations of a synchronous generator to obtain the reference value of active power. Compared with actual measured value The deviation is transformed into the dynamic behavior of the virtual rotor, enabling its virtual angular velocity to dynamically track the system's synchronous angular velocity. The virtual inertia in the controller... It provides inertial support for the system, while the damping coefficient This is used to suppress power oscillations. The deviation signal between the virtual angular velocity inside the converter and the synchronous angular velocity of the power grid is calculated by simulating a synchronous generator. Phase angle of the converter output voltage .

[0069] The inner and outer loop control can adopt the classic voltage-current dual closed-loop cascade structure. First, based on the reference value of reactive power... Compared with actual measured value The deviation is determined by the droop coefficient. Adjust the voltage reference; then calculate the current reference value via the voltage outer loop. The innermost current loop then uses the current reference value. and actual measured value The deviation generates the output converter outlet voltage This voltage, after being modulated by PWM, controls the output of VSC. This design ensures the stability and robustness of the system during dynamic response.

[0070] Collaborative damping controller module: This is the additional collaborative damping controller. This module is the core technology of this invention. This module can receive virtual angular velocity deviation signals from the main control loop. As a unified input signal, the input signal can be processed through two parallel control channels within the module.

[0071] Channel 1 is the active damping channel. This channel is specifically used to generate active damping signals. It consists of a washing-out stage and an active damping gain stage connected in series. The washing-out stage is a high-pass filter, whose function is to filter out frequency oscillation signals. The steady-state or slowly varying components of the signal are allowed to pass through, only frequency components that reflect the dynamic oscillations of the system are permitted, ensuring that the controller responds only during transient processes. The regulated signal is obtained after the washing stage. Then multiply by a pre-set active damping gain. This generates an active power modulation signal related to system oscillations. The output of this signal is connected to the reference value superposition module.

[0072] Channel two is the reactive power damping channel. This channel operates in parallel with the active power damping channel and is specifically used to generate a reactive power damping signal. Its structure is the same as the active power channel, consisting of a washing stage and a reactive power damping gain stage connected in series. The reactive power damping channel transmits the same signal... After the same filtering process, the result is obtained. Multiplied by an independently configurable reactive damping gain Generate reactive power modulation signal The output of this signal is also connected to the reference value superposition module.

[0073] From the control block diagram, the two damping channels can be logically considered to share the same washing stage, or to adopt a washing stage with completely identical parameters. The washing stage is essentially a high-pass filter, and its output is still the angular velocity deviation signal. Compared to the original input deviation signal, the adjusted signal filters out DC and low-frequency components.

[0074] As discussed above, both active and reactive power regulation are based on the same input signal reflecting system oscillations, such as virtual angular velocity deviation. Its output is used to modulate the active and reactive power reference values ​​of the converter, respectively. In practical applications, besides virtual angular velocity deviation, the active power deviation at the grid connection point or the measured frequency at the grid connection point can also be used as the unified input signal for the cooperative damping controller. It is understood that these signals can also reflect the power oscillations of the system and can serve as equivalent substitutes for the input signal of this invention.

[0075] The cooperative damping controller also includes a reference value superposition module. This module is responsible for superimposing the active / reactive power modulation signal generated by the cooperative damping controller with the basic active / reactive power reference values ​​of the main control loop. , The values ​​are superimposed to form the final power regulation control command. The reference value superposition module may further include a subtraction module and an addition module.

[0076] Active power modulation signal (active power damping signal) The active power reference value given by the main control loop is obtained through the subtraction module node. Subtracting from the middle, the final active power regulation command is formed. The active power regulation command is sent back to the grid-type main control loop to regulate the active power output of the converter.

[0077] Reactive power modulation signal (reactive power damping signal) Through an adder module node, the reactive power reference value given by the main control loop is... The summation forms the final reactive power regulation command. The reactive power regulation command is also sent back to the grid-type main control loop to regulate the reactive power output of the converter.

[0078] In some embodiments, for active damping channels and / or reactive damping channels, a phase-shifting stage can be added between the washing stage and the damping gain stage. The phase-shifting stage can be constructed using a lead-lag network, as expressed by the following equation:

[0079]

[0080] By properly configuring the time constant and It can perform phase compensation for oscillations in specific frequency bands to further optimize the damping effect in more complex system interactions.

[0081] In some embodiments, a nonlinear gain can be introduced to replace the damping gain element. Specifically, the linear gain element in the active and / or reactive power damping channels can be replaced with a nonlinear gain function.

[0082] For example, a function can be designed such that the magnitude of the gain is related to the signal. The magnitude is related. The simplest way is to use a piecewise linear function as shown below:

[0083]

[0084] in, This indicates a pre-set threshold value for the deviation signal; > This allows the controller to automatically apply a higher gain when the system experiences significant oscillations exceeding a certain threshold. To provide strong damping; when the oscillation is suppressed and the amplitude decreases, it switches to a smaller gain. To avoid over-adjustment and the introduction of high-frequency noise.

[0085] In this invention embodiment, a novel active-reactive power synergistic damping control system is provided to address power oscillations. By proposing an innovative integrated synergistic damping control strategy, the active and reactive power damping channels are configured in parallel and work collaboratively, and this strategy is integrated into the control system of a single grid-type converter. This fully utilizes the complementary advantages of the two control resources, achieving a more powerful and efficient oscillation suppression effect than any single damping method, fundamentally solving the problem of low efficiency in single-dimensional control. Simultaneously, the flexible configuration of the gains of the two independent active and reactive power channels allows technicians to flexibly balance the system's damping performance and operating costs according to actual needs, effectively resolving the inherent contradiction between stability and economy. Utilizing the synergistic effect of the active and reactive power damping mechanisms improves the adaptability of the control strategy to different grid conditions and enhances the overall robustness of the system. By constructing the power oscillation suppression system of the converter shown above, this invention embodiment achieves coordinated and synchronous modulation of active and reactive power, suppressing power oscillations through their combined action.

[0086] Reference Figure 3 This diagram illustrates a flowchart of a power oscillation suppression method for a converter according to an embodiment of the present invention. The method is applied to a power oscillation suppression system for a converter as shown in the foregoing embodiment. Specifically, the method may include the following steps:

[0087] Step 301: Output power reference value and frequency oscillation signal through the main control circuit;

[0088] In practical implementation, a power reference value and a frequency oscillation signal can be output through the main control loop. The power reference value can be the baseline active / reactive power reference value of the main control loop. , The frequency oscillation signal can be the deviation signal between the virtual angular velocity and the synchronous angular velocity of the power grid. (i.e., virtual angular velocity deviation) can also be other parameters that can reflect the power oscillation of the system, such as the active power deviation at the grid connection point or the measured frequency at the grid connection point.

[0089] Step 302: Based on the power reference value and the frequency oscillation signal, power regulation is performed through the cooperative damping controller based on active and reactive power damping cooperative control to generate a power regulation command value;

[0090] Based on the preceding embodiments, in some embodiments, the cooperative damping controller may include a washing-out stage, a damping gain stage, and a superposition module connected in series. In a specific implementation, the steps for generating a power regulation command value by performing power regulation based on active and reactive power damping cooperative control through the cooperative damping controller, according to the power reference value and the frequency oscillation signal, may include: first, filtering the frequency oscillation signal through the washing-out stage to obtain a regulated signal; then, inputting the regulated signal to the damping gain stage for gain adjustment to generate a power modulation signal; and finally, based on the power modulation signal and the power reference value, performing reference value superposition calculation through the superposition module to obtain the power regulation command value.

[0091] Furthermore, the damping gain stage can include a parallel and independently controlled active power damping gain stage and a reactive power damping gain stage. The step of inputting the regulated signal to the damping gain stage for gain adjustment to generate a power modulation signal can include: inputting the regulated signal to the active power damping gain stage for active power gain adjustment to generate an active power modulation signal; simultaneously, inputting the regulated signal to the reactive power damping gain stage for reactive power gain adjustment to generate a reactive power modulation signal.

[0092] Based on the preceding discussion, the power reference value can include both active and reactive power reference values. The power modulation signal can include both active and reactive power modulation signals. The superposition module can include both subtraction and addition modules. Therefore, the step of obtaining the power regulation command value by superimposing the reference values ​​using the superposition module based on the power modulation signal and the power reference value can include: performing reference value subtraction calculations using the subtraction module based on the active power reference value and the active power modulation signal to obtain the active power regulation command value; simultaneously, performing reference value addition calculations using the addition module based on the reactive power reference value and the reactive power modulation signal to obtain the reactive power regulation command value.

[0093] In some embodiments, a phase-shifting stage consisting of a lead-lag network can be added between the washing stage and the damping gain stage; the phase-shifting stage is used to perform phase compensation for oscillations in a preset frequency band.

[0094] In some embodiments, the damping gain element may be a linear gain element or a nonlinear gain element that is related to the amplitude of the regulated signal.

[0095] Step 303: Based on the power adjustment command value, adjust the power output of the converter through the main control loop.

[0096] In some embodiments, the power regulation command value may include an active power regulation command value and a reactive power regulation command value. The main control loop may include a virtual synchronous machine and inner and outer loop controllers. Therefore, the steps for regulating the converter's power output through the main control loop based on the power regulation command value may include the following steps S1 to S5:

[0097] Step S1: Obtain the actual measured values ​​of active power and reactive power;

[0098] Step S2: Based on the active power adjustment command value and the actual measured active power value, the output voltage phase angle of the converter is generated through the virtual synchronization control of the virtual synchronous machine;

[0099] Step S3: Input the reactive power adjustment command value to the inner and outer loop controllers, and adjust the voltage reference value through droop control according to the reactive power adjustment command value and the actual measured reactive power value.

[0100] Step S4: Based on the voltage reference value, the output voltage of the converter is generated through the voltage outer loop and current inner loop control of the inner and outer loop controllers;

[0101] Step S5: Based on the output voltage phase angle and output voltage, and combined with coordinate transformation and PWM pulse width modulation, a power control signal is generated to adjust the power output of the converter.

[0102] In this embodiment of the invention, a corresponding control method is provided for power oscillation based on an active-reactive power coordinated damping control system. First, a power reference value and a frequency oscillation signal are output through the main control loop. Then, based on the power reference value and the frequency oscillation signal, power regulation based on active-reactive power damping coordinated control is performed through the coordinated damping controller, generating a power regulation command value. Finally, based on the power regulation command value, the power output of the converter is adjusted through the main control loop. Thus, combined with the aforementioned control system, by configuring and cooperating the active and reactive power damping channels in parallel, the complementary advantages of the two control resources can be fully utilized to achieve a more powerful and efficient oscillation suppression effect than any single damping method, fundamentally solving the problem of low efficiency in single-dimensional control. Simultaneously, the flexible configuration of the gains of the two independent active and reactive power channels allows technicians to flexibly balance the system's damping performance and operating economic costs according to actual needs, effectively resolving the inherent contradiction between stability and economy. Utilizing the synergistic effect of the active and reactive power damping mechanisms can improve the adaptability of the control strategy to different power grid conditions and enhance the overall robustness of the system.

[0103] For better explanation, refer to Figure 4This diagram illustrates the overall flow of a power oscillation suppression method for a converter according to an embodiment of the present invention. It should be noted that this embodiment only provides a brief description of the general flow of power oscillation suppression for a converter. The specific implementation process of each step can be understood by referring to the relevant content in the foregoing embodiments, and will not be elaborated upon here. It is understood that the present invention does not impose any limitations on this.

[0104] Step 401: Output active / reactive power reference values ​​and frequency oscillation signals through the main control loop;

[0105] Step 402: The frequency oscillation signal is filtered through the washing-out stage of the collaborative damping controller to obtain the regulated signal;

[0106] Step 403: Input the adjusted signals to the active / reactive damping gain stage of the coordinated damping controller to adjust the active / reactive gain and generate active / reactive power modulation signals.

[0107] Step 404: Based on the active / reactive power modulation signal and the active / reactive power reference value, the reference value superposition calculation is performed by the superposition module of the coordinated damping controller to obtain the active / reactive power adjustment command value.

[0108] Step 405: Based on the active / reactive power adjustment command value, a power control signal is generated by combining the virtual synchronous machine of the main control loop and the inner and outer loop controllers to adjust the power output of the converter.

[0109] To enable those skilled in the art to better understand the technical solutions of the present invention, the following specific example is used to illustrate the embodiments of the present invention.

[0110] in, Figure 5 The figure shows the eigenvalue analysis results under different damping control scenarios. It illustrates the eigenvalue distribution, including characteristic points for four scenarios (undamped, active only, reactive only, and synergistically damped), using a constant damping ratio line as a reference. Table 1 compares the key parameters of the dominant oscillation mode (the oscillation mode with the smallest damping ratio) under the four scenarios.

[0111] Table 1: Comparison of Dominant Oscillation Modes in Different Scenarios

[0112]

[0113] It can be concluded that without any additional damping, the damping ratio of the dominant oscillation mode of the system is only 0.041. This is a typical weakly damped state with a severely insufficient stability margin. When only traditional reactive power damping is used, the damping ratio increases to 0.047, but the improvement effect is almost negligible and cannot meet engineering requirements. In contrast, when only active power damping is used, the damping ratio can be significantly improved to 0.125, proving the effectiveness of active power regulation.

[0114] The active-reactive power coordinated damping scheme proposed in this invention further improves the damping ratio to 0.130, achieving the best effect among all compared schemes. The physical significance of this result is that the active-reactive power coordinated control strategy provided by this invention can most effectively push the system's oscillation mode point (i.e., eigenvalue) deeper into the left half of the S-complex plane, thereby providing the strongest damping for the system and solving the weak damping problem of grid-type converters under weak power grid conditions.

[0115] The active power transient response curves under different damping control strategies are shown in the figure. Figure 6 As shown in the figure, this figure illustrates the active power response curves of the system after a fault occurs at 10 seconds and is cleared at 10.2 seconds under four different scenarios.

[0116] As can be seen, after simulating a severe power grid fault, the undamped system exhibited severe power oscillations lasting over 10 seconds. The system with only reactive power damping showed no significant improvement. While traditional active power damping schemes effectively suppressed oscillations, it still required approximately 4-5 seconds for the system to converge. In stark contrast, the active-reactive power synergistic damping scheme of this invention suppressed power oscillations most quickly and effectively, achieving complete stability in only about 2-3 seconds. This fully demonstrates that this invention, through synergistic action, perfectly combines the direct and powerful regulation of the system's power angle by active power with the rapid support of the grid connection voltage by reactive power, achieving the fastest transient recovery speed and effectively solving the problems of slow transient recovery and long oscillation time in existing technologies.

[0117] The feasibility of the technical solution of this invention has been fully verified through detailed simulation experiments. The simulation results also clearly demonstrate the significant advantages of this invention compared to current technologies. On the one hand, the small disturbance analysis results provide quantitative evidence of the superiority of the technical solution of this invention, thereby significantly enhancing the small-signal stability of the system and effectively solving the weak damping problem. On the other hand, the transient simulation results intuitively demonstrate the superior ability of the technical solution of this invention to suppress large disturbances, thereby greatly improving the transient performance of the system and solving the problem of slow transient recovery.

[0118] Reference Figure 7This diagram illustrates a structural block diagram of a power oscillation suppression device for a converter according to an embodiment of the present invention. The device is applied to a power oscillation suppression system for a converter as shown in the foregoing embodiment. Specifically, the device may include:

[0119] Data output unit 701 is used to output power reference value and frequency oscillation signal through the main control circuit;

[0120] The power regulation unit 702 is used to perform power regulation based on active and reactive power damping coordinated control through the coordinated damping controller according to the power reference value and the frequency oscillation signal, and generate a power regulation command value.

[0121] The power output control unit 703 is used to adjust the power output of the converter through the main control loop based on the power adjustment command value.

[0122] In one optional embodiment, the cooperative damping controller includes a washing-out stage, a damping gain stage, and a superposition module connected in series; the power adjustment unit 702 includes:

[0123] The filtering unit is used to filter the frequency oscillation signal through the washing stage to obtain the adjusted signal.

[0124] A gain adjustment unit is used to input the adjusted signal to the damping gain stage for gain adjustment and generate a power modulation signal.

[0125] The reference value superposition calculation unit is used to perform reference value superposition calculation based on the power modulation signal and the power reference value through the superposition module to obtain the power adjustment command value.

[0126] In one optional embodiment, the damping gain stage includes a parallel and independently controlled active power damping gain stage and a reactive power damping gain stage; the gain adjustment unit includes:

[0127] The active power gain adjustment unit is used to input the adjusted signal to the active power damping gain stage for active power gain adjustment and generate an active power modulation signal.

[0128] The reactive power gain adjustment unit is used to input the adjusted signal to the reactive power damping gain stage for reactive power gain adjustment, thereby generating a reactive power modulation signal.

[0129] In one optional embodiment, the power reference value includes an active power reference value and a reactive power reference value; the power modulation signal includes an active power modulation signal and a reactive power modulation signal; the superposition module includes a subtraction module and an addition module; the reference value superposition calculation unit includes:

[0130] The reference value subtraction calculation unit is used to perform reference value subtraction calculation through the subtraction module based on the active power reference value and the active power modulation signal to obtain the active power adjustment command value.

[0131] The reference value addition calculation unit is used to perform reference value addition calculation through the addition module based on the reactive power reference value and the reactive power modulation signal to obtain the reactive power adjustment command value.

[0132] In one optional embodiment, a phase-shifting stage composed of a lead-lag network is added between the washing stage and the damping gain stage; the phase-shifting stage is used to perform phase compensation for oscillations in a preset frequency band.

[0133] In one alternative embodiment, the damping gain element is a linear gain element, or a nonlinear gain element that is related to the amplitude of the adjusted signal.

[0134] In one optional embodiment, the power regulation command value includes an active power regulation command value and a reactive power regulation command value; the main control loop includes a virtual synchronizer and inner and outer loop controllers; the power output control unit 703 includes:

[0135] The actual measurement data acquisition unit is used to acquire the actual measured values ​​of active power and reactive power.

[0136] The virtual synchronization control unit is used to generate the output voltage phase angle of the converter through the virtual synchronization control of the virtual synchronizing machine, based on the active power adjustment command value and the actual measured value of the active power.

[0137] The droop control unit is used to input the reactive power adjustment command value to the inner and outer loop controllers, and adjust the voltage reference value through droop control according to the reactive power adjustment command value and the actual measured value of reactive power.

[0138] The inner and outer loop control units are used to generate the output voltage of the converter based on the voltage reference value through the voltage outer loop and current inner loop control of the inner and outer loop controllers;

[0139] A power control signal generation unit is used to generate a power control signal based on the output voltage phase angle and the output voltage, combined with coordinate transformation and PWM pulse width modulation, so as to adjust the power output of the converter based on the power control signal.

[0140] As the device embodiment is basically similar to the method embodiment, it is described in a relatively simple way. For relevant details, please refer to the description of the method embodiment above.

[0141] This invention also provides an electronic device, which includes a processor and a memory:

[0142] The memory is used to store program code and transfer the program code to the processor;

[0143] The processor is used to execute the power oscillation suppression method of the converter according to the instructions in the program code of any embodiment of the present invention.

[0144] This invention also provides a computer-readable storage medium for storing program code for executing the power oscillation suppression method for a converter according to any embodiment of this invention.

[0145] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0146] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this invention are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of related data must comply with the relevant laws, regulations and standards of the relevant countries and regions, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0147] In the embodiments provided by this invention, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between devices or units through some interfaces, and may be electrical, mechanical, or other forms.

[0148] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0149] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0150] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0151] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for suppressing power oscillations in a converter, characterized in that, A power oscillation suppression system applied to a converter, the power oscillation suppression system comprising a main control loop and a cooperative damping controller; the method comprising: The main control circuit outputs a power reference value and a frequency oscillation signal. Based on the power reference value and the frequency oscillation signal, the power regulation is performed by the cooperative damping controller based on active and reactive power damping cooperative control, and a power regulation command value is generated. Based on the power adjustment command value, the power output of the converter is adjusted through the main control loop.

2. The power oscillation suppression method for a converter according to claim 1, characterized in that, The coordinated damping controller includes a washing-out stage, a damping gain stage, and a superposition module connected in series; the power regulation based on active and reactive power damping coordinated control, generated by the coordinated damping controller according to the power reference value and the frequency oscillation signal, includes: The frequency oscillation signal is filtered through the washing process to obtain the adjusted signal. The adjusted signal is input to the damping gain stage for gain adjustment to generate a power modulation signal; Based on the power modulation signal and the power reference value, the power adjustment command value is obtained by superimposing the reference value through the superposition module.

3. The power oscillation suppression method for a converter according to claim 2, characterized in that, The damping gain stage includes a parallel and independently controlled active damping gain stage and a reactive damping gain stage. The step of inputting the adjusted signal to the damping gain stage for gain adjustment to generate a power modulation signal includes: The adjusted signal is input to the active power damping gain stage for active power gain adjustment to generate an active power modulation signal. The adjusted signal is input to the reactive power damping gain stage for reactive power gain adjustment, thereby generating a reactive power modulation signal.

4. The power oscillation suppression method for a converter according to claim 2, characterized in that, The power reference value includes an active power reference value and a reactive power reference value; the power modulation signal includes an active power modulation signal and a reactive power modulation signal; the superposition module includes a subtraction module and an addition module; The step of obtaining a power adjustment command value by superimposing reference values ​​through the superposition module based on the power modulation signal and the power reference value includes: Based on the active power reference value and the active power modulation signal, the active power adjustment command value is obtained by subtracting the reference value through the subtraction module. Based on the reactive power reference value and the reactive power modulation signal, the reactive power adjustment command value is obtained by performing reference value addition calculation through the addition module.

5. The power oscillation suppression method for a converter according to claim 2, characterized in that, A phase-shifting stage composed of a lead-lag network is added between the washing stage and the damping gain stage; the phase-shifting stage is used to perform phase compensation for oscillations in a preset frequency band.

6. The power oscillation suppression method for a converter according to claim 2, characterized in that, The damping gain element is either a linear gain element or a nonlinear gain element that is related to the amplitude of the adjusted signal.

7. The power oscillation suppression method for a converter according to any one of claims 1 to 6, characterized in that, The power regulation command value includes an active power regulation command value and a reactive power regulation command value; the main control loop includes a virtual synchronous machine and inner and outer loop controllers; the adjustment of the converter's power output through the main control loop based on the power regulation command value includes: Obtain the actual measured values ​​of active power and reactive power; Based on the active power adjustment command value and the actual measured active power value, the output voltage phase angle of the converter is generated through the virtual synchronization control of the virtual synchronizing machine. The reactive power adjustment command value is input to the inner and outer loop controllers. Based on the reactive power adjustment command value and the actual measured reactive power value, the voltage reference value is adjusted by droop control. Based on the voltage reference value, the output voltage of the converter is generated through the voltage outer loop and current inner loop control of the inner and outer loop controllers; Based on the output voltage phase angle and the output voltage, a power control signal is generated by combining coordinate transformation and PWM pulse width modulation, so as to adjust the power output of the converter based on the power control signal.

8. A power oscillation suppression device for a converter, characterized in that, A power oscillation suppression system applied to a converter, the power oscillation suppression system including a main control loop and a cooperative damping controller; the device includes: The data output unit is used to output a power reference value and a frequency oscillation signal through the main control circuit; The power regulation unit is used to perform power regulation based on active and reactive power damping coordinated control through the coordinated damping controller according to the power reference value and the frequency oscillation signal, and generate a power regulation command value. A power output control unit is used to adjust the power output of the converter through the main control loop based on the power adjustment command value.

9. An electronic device, characterized in that, The device includes a processor and a memory: The memory is used to store program code and transmit the program code to the processor; The processor is configured to execute the power oscillation suppression method for the converter according to any one of claims 1-7, based on the instructions in the program code.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store program code for executing the power oscillation suppression method for the converter according to any one of claims 1-7.

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