External new energy additional damping control method, device and equipment

Abstract

The application provides an external new energy additional damping control method, device and equipment, and relates to the technical field of new energy grid connection control. The method comprises the following steps: obtaining operation data of a new energy converter grid connection point to be controlled; calculating active power oscillation and analyzing oscillation period according to the operation data, determining effective oscillation based on a double threshold value, and extracting an original oscillation power component from real-time active power when the effective oscillation exists; identifying a phase lag amount of a full link according to the original oscillation power component, and performing phase compensation on the original oscillation power component according to the phase lag amount to obtain a compensated oscillation power component; calculating a real-time gain matching coefficient according to an oscillation envelope of the original oscillation power component; generating a control instruction according to the compensated oscillation power component and the real-time gain matching coefficient, and sending the control instruction to the new energy converter to realize additional damping control. The application can improve the stability of power grid operation.

Description

Technical Field

[0001] This invention relates to the field of new energy grid connection control technology, and in particular to an external new energy additional damping control method, device and equipment. Background Technology

[0002] With the large-scale grid connection of new energy sources such as wind power and photovoltaics, the power system's electronic characteristics have been significantly enhanced. New energy converters are multi-grid controlled and lack the inherent rotor damping of synchronous units. Under weak grid conditions, they are prone to low-frequency, subsynchronous power oscillations, which seriously threaten the safe and stable operation of the power grid.

[0003] To address the aforementioned oscillation problem, the current mainstream solutions for suppressing oscillations in new energy sources are all based on the modification of the converter. However, this solution has significant engineering limitations. The built-in damping algorithm requires the equipment manufacturer to open up the converter's underlying control parameters and program interface. Existing equipment is generally not suitable for modification, has poor versatility, and has high modification costs.

[0004] In addition, all traditional damping controls have inherent performance shortcomings. They all adopt static fixed parameter control mode, which has limited adaptability to operating conditions and makes it difficult to completely eliminate system power oscillations. The oscillations persist repeatedly and continuously affect the stable operation of the power grid. Summary of the Invention

[0005] This invention provides an external renewable energy additional damping control method, device, and equipment to solve the problem that existing damping control methods are unable to completely eliminate system power oscillations, thus affecting the stable operation of the power grid.

[0006] In a first aspect, embodiments of the present invention provide an external renewable energy additional damping control method, comprising: acquiring operating data of the grid connection point of the renewable energy converter to be controlled; wherein, the operating data includes real-time active power, bus voltage, and grid connection current; calculating the active power oscillation quantity and analyzing the oscillation period based on the operating data, determining effective oscillation based on a dual threshold, and extracting the original oscillation power component from the real-time active power when effective oscillation exists; identifying the phase lag of the entire link based on the original oscillation power component, and performing phase compensation on the original oscillation power component based on the phase lag to obtain the compensated oscillation power component; calculating the real-time gain matching coefficient based on the oscillation envelope of the original oscillation power component; generating a control command based on the compensated oscillation power component and the real-time gain matching coefficient, and sending the control command to the renewable energy converter to realize additional damping control.

[0007] In one possible implementation, the active power oscillation is calculated based on operating data, and the oscillation period is analyzed. Valid oscillation is determined based on a dual threshold, including: extracting the active power oscillation time-domain waveform based on real-time active power; calculating the oscillation amplitude within a preset window based on the peak and valley values ​​of the active power oscillation time-domain waveform, which is used as the active power oscillation; determining the complete waveform of a single oscillation based on the active power oscillation time-domain waveform; determining the number of oscillation periods based on the complete waveform of a single oscillation; and determining that valid oscillation exists if the active power oscillation is greater than or equal to a preset oscillation threshold and the number of oscillation periods is greater than or equal to a preset oscillation period threshold.

[0008] In one possible implementation, the phase lag of the entire link is identified based on the original oscillation power component, including: determining the phase timing curve of the original oscillation power component and its feedback oscillation power based on the original oscillation power component; and calculating the phase lag by subtracting the phase of the original oscillation power component and the feedback oscillation power at the same time.

[0009] In one possible implementation, phase compensation is performed on the original oscillation power component based on the phase lag to obtain the compensated oscillation power component, including: calculating the equivalent delay based on the phase lag and the center frequency; calculating the lead compensation angle based on the equivalent delay and the center frequency; and determining the compensated oscillation power component based on the original oscillation power component and the lead compensation angle.

[0010] In one possible implementation, the real-time gain matching coefficient is calculated based on the oscillation envelope of the original oscillation power component, including: setting an initial gain matching coefficient according to the oscillation frequency band type; calculating the decay time constant corresponding to the oscillation envelope of the original oscillation power component within a preset number of dominant oscillation cycles; adaptively adjusting the initial gain matching coefficient based on the decay time constant, a first threshold value, and a second threshold value, combined with a preset adjustment step size, upper gain limit, and lower gain limit, to obtain the real-time gain matching coefficient; the second threshold value is less than the first threshold value; wherein, when the decay time constant is greater than the first threshold value, the real-time gain matching coefficient is increased sequentially in each control cycle; when the decay time constant is less than the second threshold value, the real-time gain matching coefficient is decreased sequentially in each control cycle; when the decay time constant is greater than or equal to the second threshold value and less than or equal to the first threshold value, the real-time gain matching coefficient remains unchanged.

[0011] In one possible implementation, a control command is generated based on the compensated oscillation power component and the real-time gain matching coefficient, including: multiplying the compensated oscillation power component and the real-time gain matching coefficient to obtain the original damping adjustment amount; performing amplitude limiting and rate of change limiting on the original damping adjustment amount to obtain the processed damping adjustment amount; and using the processed damping adjustment amount as the control command.

[0012] In one possible implementation, after implementing additional damping control, the method further includes: detecting the oscillation peak value and the oscillation envelope fitting slope within a preset time window; when the oscillation peak value is greater than a preset proportional threshold and the oscillation envelope fitting slope is positive within a preset time, divergent oscillation is determined to occur, the damping correction amount in the control command is smoothly reduced to zero according to the preset slope and the control output is locked, and after a delay, the real-time gain matching coefficient is reduced and control is re-engaged; if divergent oscillation is detected again after re-engaging control, the control function is permanently locked and an alarm signal is output.

[0013] In one possible implementation, after implementing additional damping control, the method further includes: calculating the remaining available capacity of each converter based on its rated power and current operating power; and allocating the damping correction amount in the control command based on the remaining available capacity of each converter.

[0014] Secondly, embodiments of the present invention provide an external renewable energy additional damping control device, comprising: a signal acquisition module for acquiring operating data of the grid connection point of the renewable energy converter to be controlled; wherein the operating data includes real-time active power, bus voltage, and grid connection current; a core processing module for calculating the active power oscillation quantity and analyzing the oscillation period based on the operating data, determining effective oscillation based on dual thresholds, extracting the original oscillation power component from the real-time active power when effective oscillation exists; identifying the phase lag of the entire link based on the original oscillation power component, and performing phase compensation on the original oscillation power component based on the phase lag to obtain the compensated oscillation power component; calculating the real-time gain matching coefficient based on the oscillation envelope of the original oscillation power component; generating a control command based on the compensated oscillation power component and the real-time gain matching coefficient, and sending the control command to the renewable energy converter to realize additional damping control.

[0015] Thirdly, embodiments of the present invention provide an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method described in the first aspect or any possible implementation thereof.

[0016] This invention provides an external renewable energy additional damping control method, device, and equipment. First, by using a dual-threshold discrimination method based on active power oscillation quantity and oscillation period, it can filter out instantaneous random power disturbances in the power grid, distinguish between short-term ineffective disturbances and continuous active power oscillations, effectively avoiding problems such as erroneous switching and operation of damping control, and improving the anti-interference performance of the entire control strategy. Second, it identifies and compensates for phase lag generated throughout the control link, corrects timing deviations in the damping control signal, and ensures that the output damping signal is phase-matched and synchronized with the active power oscillations of the power grid, avoiding the risk of amplifying grid oscillations due to phase shift. Simultaneously, it calculates the real-time gain matching coefficient based on the oscillation envelope of the original oscillation power component, and dynamically adjusts the damping control intensity according to the oscillation decay state. Finally, by using an external control architecture to issue damping control commands, without modifying the converter's underlying control program, it can quickly and non-intrusively smooth out active power oscillations at the grid connection point, continuously improving the dynamic stability of the power grid and ensuring the long-term safe operation of the renewable energy grid-connected system. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the external new energy auxiliary damping control system provided in an embodiment of the present invention; Figure 2 This is a flowchart illustrating the implementation of the external new energy additional damping control method provided in this embodiment of the invention. Figure 3 This is a logic diagram of the external new energy additional damping control method provided in the embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of the external new energy additional damping control device provided in the embodiment of the present invention; Figure 5 This is a schematic diagram of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0018] With the large-scale grid connection of new energy sources, the power grid exhibits characteristics of low inertia and high power electronics. Wind power, photovoltaic, and grid-connected converters lack the physical rotor damping of synchronous machines and the oscillation damping suppression capability of power system stabilizers (PSS) in thermal power. At the same time, many existing converter manufacturers do not disclose the underlying control parameters, making it impossible to implement built-in damping control logic modifications.

[0019] To address the shortcomings of existing renewable energy oscillation mitigation technologies, current external damping control technology faces three major technical bottlenecks: difficulty in accurately compensating for end-to-end phase lag (multi-stage delays in sampling, computation, communication, and converter response lead to unknown phase), lack of matching basis for external command amplitudes (the inherent gain of the converter's dual closed-loop system makes fixed gains prone to underdamping or over-adjustment shocks), and lack of adaptive capability under operating conditions (dynamic changes in grid short-circuit capacity, output, and oscillation frequency lead to mismatch in fixed parameters). Currently, there is a lack of a complete, non-intrusive external control logic that encompasses oscillation signal extraction, dynamic phase compensation, and adaptive gain matching. This technological gap severely restricts the improvement of oscillation mitigation capabilities in high-proportion renewable energy power grids.

[0020] This invention aims to provide an external renewable energy additional damping control method. Through a non-intrusive external control architecture, it achieves full-process adaptive damping control without modifying the underlying control parameters and control logic of the converter. Relying on the measured electrical quantities at the grid connection point, it accurately compensates for phase lag across the entire link, dynamically matches damping gain, intelligently distributes multi-machine adjustment commands, and is equipped with a complete abnormal protection logic. It effectively solves the technical problems of inaccurate phase compensation, poor gain adaptability, high difficulty in modification, and easy induction of secondary oscillation in existing technologies, and significantly improves the dynamic stability level of high-proportion renewable energy grid-connected systems.

[0021] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0022] The external renewable energy additional damping control method of the present invention is implemented based on the external renewable energy additional damping control system. Figure 1 This is a schematic diagram of the external new energy auxiliary damping control system provided in an embodiment of the present invention. Figure 1 As shown, the external renewable energy additional damping control system includes an external renewable energy additional damping control device, a converter controller, and multiple converters. The external renewable energy additional damping control device is independent of the original converter controller and connects to multiple renewable energy converters by outputting damping correction values ​​to achieve non-intrusive additional damping control.

[0023] Specifically, the external renewable energy additional damping control device comprises five main internal functional modules (power supply module, human-machine interface module, core processing module, signal acquisition module, and output module), plus a back-end converter control execution layer. The power supply module provides hardware power support, the signal acquisition module acquires raw electrical data from the power grid and sends it to the core processing module, which runs all core algorithms for oscillation identification, phase compensation, adaptive gain, and safety protection to generate the total damping adjustment. The output module completes the capacity distribution among multiple units and outputs damping correction signals to each converter. The human-machine interface module runs throughout the entire process, enabling visualized interaction of parameter configuration, operating status, and fault information. The entire device is independently connected to the existing converter control system, using a power increment method to suppress low-frequency oscillations.

[0024] See Figure 2 The flowchart illustrating the implementation of the external new energy additional damping control method provided in the embodiment of the present invention is shown below: Step 201: Obtain the operating data of the grid connection point of the new energy converter to be controlled; wherein, the operating data includes real-time active power, bus voltage and grid connection current.

[0025] In the specific implementation process, the three-phase voltage and three-phase current electrical quantities at the grid connection point of the new energy converter are collected in real time, and the active power, reactive power and real-time grid frequency at the grid connection point are calculated in real time based on the collected electrical quantities.

[0026] In this embodiment, three basic electrical quantities—real-time active power, bus voltage, and grid-connected current—are synchronously collected at the grid connection point to fully reconstruct the real-time operating status of the new energy grid-connected system. This provides complete and reliable raw data support for subsequent oscillation identification, phase lag identification, and damping adjustment calculations. Relying solely on active power is prone to misjudgment of disturbances; joint sampling of multiple electrical quantities improves the accuracy of operating condition identification.

[0027] Step 202: Calculate the active power oscillation based on the operating data and analyze the oscillation period. Determine the effective oscillation based on the dual threshold. When there is an effective oscillation, extract the original oscillation power component from the real-time active power.

[0028] In some embodiments, active power oscillation is the amplitude of active power fluctuations, characterizing the strength of the oscillation. The dual thresholds consist of two types of judgment thresholds: a preset oscillation magnitude threshold and a preset oscillation period threshold. Only when both conditions are met is it considered a true oscillation. Effective oscillation is a persistent, low-frequency power oscillation that threatens grid stability, distinguishing it from short-term ineffective disturbances such as instantaneous lightning strikes and load surges. The original oscillation power component is the pure AC fluctuation component separated from the steady-state constant active power after removing it from the real-time active power.

[0029] In the specific implementation process, the real-time active power signal is analyzed for oscillation characteristics and effective oscillation is determined. The dominant oscillation frequency, oscillation amplitude, and number of consecutive oscillation cycles of the power grid are extracted by fast Fourier transform or frequency-locked loop. The real-time oscillation amplitude and the number of consecutive oscillation cycles are compared with preset oscillation quantity thresholds and preset oscillation cycle thresholds, respectively. Only when the oscillation amplitude exceeds the preset oscillation quantity threshold and the number of consecutive oscillation cycles exceeds the preset oscillation cycle threshold is it determined that there is effective power oscillation in the power grid, and the subsequent damping control logic is initiated; otherwise, it is determined that the power grid is in steady state or has a slight fluctuation, the output of the damping power correction is blocked, and the correction is kept at 0 to avoid invalid calculations and erroneous adjustments.

[0030] For effective oscillation conditions, the bandpass filter parameters are adaptively tuned based on the dominant oscillation frequency to filter out steady-state power components and clutter interference, extracting the original active oscillation power components. The specific filtering configuration rules are as follows: 1) Original oscillation component ΔP(t): Instantaneous active power P(t) is calculated from the grid connection point voltage and current. The center frequency, upper and lower cutoff frequencies, filter order, and quality factor of the bandpass filter are adaptively configured based on the real-time dominant oscillation frequency f_osc. ①Low-frequency oscillation: center frequency = f_osc, upper and lower cutoff bandwidth ±0.1Hz, 4th order bandpass, quality factor Q=10; ② Subsynchronous oscillation: center frequency = f_osc, upper and lower cutoff bandwidth ±0.5Hz, 3rd order bandpass, quality factor Q=8; An adaptive bandpass filter is used to filter out steady-state active power, power frequency noise, and low-frequency drift components, and the original oscillation power ΔP(t) is output.

[0031] In this embodiment, valid oscillations are screened based on a combined threshold of oscillation magnitude and oscillation period, distinguishing between short-term disturbances and continuous oscillations, avoiding erroneous triggering of control logic, and improving the overall control's anti-interference capability. Only after valid oscillations are identified are the oscillation components extracted, the steady-state active power component filtered out, and the pure power fluctuation signal separated. The bandpass filter parameters are adaptively tuned with the real-time main frequency, accommodating various oscillation scenarios and applicable to all types of new energy power plants.

[0032] Step 203: Identify the phase lag of the entire link based on the original oscillation power component, and perform phase compensation on the original oscillation power component based on the phase lag to obtain the compensated oscillation power component.

[0033] In some embodiments, the end-to-end link is a complete signal path, encompassing the entire closed-loop path from grid connection point signal acquisition, internal device calculation, control command output, and converter power execution. The end-to-end link includes all stages of sampling, communication, calculation, and power conversion. Phase lag is the phase shift difference between the output waveform and the input waveform after the signal has passed through the end-to-end link. Phase compensation is a correction operation that cancels out the phase lag of the end-to-end link through a lead angle. The compensated oscillation power component is the oscillation signal after phase lead correction and synchronization with the grid oscillation timing.

[0034] In this embodiment, the overall phase lag accumulated in the entire control signal path is identified, and phase compensation correction is performed on the oscillation signal to eliminate the phase deviation caused by signal transmission and control execution, so that the timing of the oscillation signal matches the actual oscillation of the power grid, avoids phase mismatch causing oscillation to intensify, and ensures that subsequent damping adjustment can play a positive role in suppressing oscillation.

[0035] Step 204: Calculate the real-time gain matching coefficient based on the oscillation envelope of the original oscillation power component.

[0036] In some embodiments, the oscillation envelope is a contour curve formed by connecting all peaks of the active oscillation waveform, and the rising or falling trend of the envelope directly reflects the convergence or divergence state of the oscillation. The real-time gain matching coefficient is a dynamically adjustable damping amplification coefficient, which is updated with the oscillation state in each control cycle.

[0037] In this embodiment, the damping gain is calculated in real time based on the amplitude change profile of the oscillation waveform. The damping adjustment intensity can be dynamically matched with the oscillation fluctuation state, providing corresponding control intensity for oscillations of different strengths and different convergence trends, thereby improving the adaptability of oscillation suppression.

[0038] Step 205: Generate control commands based on the compensated oscillation power components and real-time gain matching coefficients, and send the control commands to the new energy converter to achieve additional damping control.

[0039] In some embodiments, the control command is an additional adjustment increment of active power that is double-limited and finally issued to the converter. Additional damping control is an external device that independently generates power correction commands and superimposes them on the original active power setpoint of the converter. It does not modify the underlying program of the converter and belongs to non-intrusive external damping regulation.

[0040] In this embodiment, the phase-corrected oscillation signal and the real-time matched gain synthesized damping control command are directly sent to the new energy converter to apply additional regulation. By relying on external additional regulation, the active power oscillation at the grid connection point is smoothed out, thereby improving the operational stability of the new energy grid connection system.

[0041] This invention provides an external renewable energy-additional damping control method. First, by using a dual-threshold discrimination method based on active power oscillation quantity and oscillation period, it can filter out instantaneous random power disturbances in the power grid, distinguish between short-term ineffective disturbances and continuous active power oscillations, effectively avoiding problems such as erroneous switching and operation of damping control, and improving the anti-interference performance of the entire control strategy. Second, it identifies and compensates for phase lag generated throughout the control link, corrects timing deviations in the damping control signal, and ensures that the output damping signal is phase-matched and synchronized with the active power oscillations of the power grid, avoiding the risk of amplifying grid oscillations due to phase shift. Simultaneously, it calculates the real-time gain matching coefficient based on the oscillation envelope of the original oscillation power components, dynamically adjusting the damping control intensity according to the oscillation decay state. Finally, it uses an external control architecture to issue damping control commands without modifying the converter's underlying control program, rapidly smoothing active power oscillations at the grid connection point in a non-intrusive manner, continuously improving the dynamic stability of the power grid, and ensuring the long-term safe operation of the renewable energy grid-connected system.

[0042] The overall core process of the damping control method of the present invention has been described above. In order to further refine the core implementation logic corresponding to the technical solution, the following will break down and elaborate on the detailed implementation methods, quantitative judgment rules and standardized execution processes of each key subordinate technical point of the present invention.

[0043] In one possible implementation, the active power oscillation is calculated based on operating data, and the oscillation period is analyzed. Valid oscillation is determined based on a dual threshold, including: extracting the active power oscillation time-domain waveform based on real-time active power; calculating the oscillation amplitude within a preset window based on the peak and valley values ​​of the active power oscillation time-domain waveform, which is used as the active power oscillation; determining the complete waveform of a single oscillation based on the active power oscillation time-domain waveform; determining the number of oscillation periods based on the complete waveform of a single oscillation; and determining that valid oscillation exists if the active power oscillation is greater than or equal to a preset oscillation threshold and the number of oscillation periods is greater than or equal to a preset oscillation period threshold.

[0044] In some embodiments, the active power oscillation time-domain waveform is the active power fluctuation curve that varies with time after the constant DC active power is removed. The horizontal axis represents time and the vertical axis represents the active power fluctuation amplitude, which intuitively reflects the power oscillation process. The complete waveform of a single oscillation is an entire active power fluctuation curve that goes from the trough to the peak and back to the trough or the baseline within a complete cycle, representing a complete power oscillation.

[0045] To adapt to actual engineering applications, this invention sets preferred engineering trigger thresholds: the preset oscillation threshold is 1%~3% of the converter's rated power, with a typical embodiment using 2%; when the peak-to-peak value of the oscillation is less than this value, it is determined to be normal power fluctuation of the system, and damping control is not activated; the preset oscillation period threshold is 3~5 periods, with a typical embodiment using 4 periods; this avoids single instantaneous disturbances and random pulses from falsely triggering damping action. The overall triggering logic follows this principle: only when the oscillation amplitude is greater than or equal to 2% of the rated power, and the continuous effective oscillation period is greater than or equal to 4, is it determined to be continuous grid power oscillation, and the entire process of phase compensation, gain calculation, and damping correction output is activated; under other operating conditions, the damping output is locked at 0.

[0046] In this embodiment, a pure oscillating waveform is separated from the original active power data, which contains both steady-state load power and oscillating fluctuation power. Interference from the steady-state DC component is eliminated, retaining only the oscillation signal for oscillation judgment. This simplifies the calculation of subsequent oscillation amplitude and period identification, improving the accuracy of waveform feature recognition. The intensity of oscillation is rapidly quantified based on the extreme values ​​of the waveform within a sliding window. The time-domain peak-valley value calculation logic is simple and real-time, quickly outputting quantitative indicators characterizing the strength of oscillations, providing an intuitive and reliable numerical basis for subsequent amplitude threshold judgment. Based on the pure oscillating time-domain waveform, an independent and complete round of power fluctuation is identified, accurately defining the start and end boundaries of each oscillation, avoiding waveform truncation and half-wave misjudgment, and providing a complete and standard identification unit for statistically analyzing oscillation duration. The total number of complete oscillation waveforms within the statistical window quantifies the duration of oscillations. Amplitude alone cannot distinguish between short-term disturbances and long-term oscillations; the number of periods can supplement the characterization of oscillation persistence. A dual-condition judgment based on oscillation amplitude and oscillation duration period is used; only when the oscillation amplitude is sufficiently large and lasts for a sufficient number of complete periods is it considered a harmful and effective oscillation. It can effectively filter instantaneous short-term disturbances such as lightning strikes and load switching, prevent meaningless false starts of damping control, and significantly improve the anti-interference capability of the entire control strategy. This invention features a unique dual-threshold triggering mechanism of oscillation amplitude and continuous period, which activates damping output only under continuous real oscillation conditions, and blocks damping commands in steady-state grid, instantaneous disturbance, and weak fluctuation scenarios, completely solving the shortcomings of traditional damping control in long-term steady-state disturbances.

[0047] After completing the effective oscillation identification and the extraction of the original oscillation components, the accurate identification of the phase lag of the entire link is the core prerequisite for realizing positive damping control. This invention specifically designs a phase lag identification scheme for comparing the first and last signals.

[0048] In one possible implementation, the phase lag of the entire link is identified based on the original oscillation power component, including: determining the phase timing curve of the original oscillation power component and its feedback oscillation power based on the original oscillation power component; and calculating the phase lag by subtracting the phase of the original oscillation power component and the feedback oscillation power at the same time.

[0049] In some embodiments, the feedback oscillation power is the active oscillation waveform transmitted back from the grid connection point after the converter performs power regulation; it is the end-point response signal after passing through the entire control path. The phase-time curve is a curve plotted with time on the horizontal axis and the instantaneous phase of the oscillation signal on the vertical axis, which can intuitively reflect the phase value of the oscillation signal at any given time.

[0050] In the specific implementation process, the amplitude of the phase-compensated oscillation power component ΔP_comp(t) is taken from the measured amplitude of the original oscillation power after filtering. The delay of the basic system is calibrated by offline step test. Small test signals are periodically injected into the active power reference interface of the converter to identify the total phase lag of the entire link under the current operating condition. The dynamic lead phase compensation angle is calculated by combining the real-time dominant oscillation frequency. The phase lead compensation angle is used to perform phase forward correction on the original active oscillation power component to obtain the phase-pre-compensated oscillation power component.

[0051] In this embodiment, the phase curves of the two oscillation signals—the excitation signal at the start of the link and the feedback signal at the end of the link—are simultaneously acquired, continuously changing over time, fully covering the input and output signals of the entire control link. Phase changes are recorded uniformly in the form of time-series curves, providing continuous and standardized phase data that can be calculated point-by-point for subsequent accurate comparison of phase differences, avoiding phase identification errors caused by single-point sampling. Phase difference calculations are performed on the first and last oscillation signals under the same time reference, and the calculation results fully encompass the comprehensive phase offset superimposed by all stages of sampling, control calculation, communication transmission, and converter power conversion. The total lag of the entire control path is accurately quantified, yielding a quantitative index that can be directly used for phase compensation, providing an accurate calculation basis for subsequent elimination of timing mismatch and prevention of oscillation deterioration.

[0052] After accurately identifying the phase lag across the entire link, the phase deviation needs to be converted into a feasible compensation angle through standardized conversion logic to complete the timing correction of the oscillation signal.

[0053] In one possible implementation, phase compensation is performed on the original oscillation power component based on the phase lag to obtain the compensated oscillation power component, including: calculating the equivalent delay based on the phase lag and the center frequency; calculating the lead compensation angle based on the equivalent delay and the center frequency; and determining the compensated oscillation power component based on the original oscillation power component and the lead compensation angle.

[0054] In some embodiments, the center frequency is the characteristic oscillation frequency of the current dominant active power oscillation, which is the main frequency of the oscillation to be suppressed in this round. The equivalent delay is calculated by converting the phase lag and oscillation frequency; it represents the equivalent time delay corresponding to signal transmission and processing throughout the entire link, transforming the phase shift into a visually apparent time delay. The lead compensation angle is a positive phase shift used to offset the phase lag caused by the equivalent delay throughout the entire link. When superimposed on the original oscillation signal, it allows the output damping signal to lead the corresponding lag time, achieving phase synchronization correction.

[0055] In its implementation, this invention employs a combination of offline calibration and online dynamic identification to achieve accurate compensation. The specific execution process is as follows: ① Offline calibration: In the initial stage of equipment commissioning, inject a small step power signal (≤3% of rated power) into the active power reference interface, collect the active power response waveform at the grid connection point, and take the time for the power change to reach 63.2% of the steady state as the basic equivalent delay τ; ②Online dynamic identification: When the device is running in steady state, a sweep frequency sinusoidal test signal with an amplitude ≤ 2% of the rated power is injected into the active power interface of the converter at fixed intervals. The active power output waveform at the grid connection point is collected synchronously. The discrete Fourier transform is used to analyze the input signal phase θ_in and the output response phase θ_out to obtain the phase lag Δθ = θ_in - θ_out at the current frequency. ③Equivalent delay for update: ; ④ Calculation of advance compensation angle: ; ⑤ Signal phase forward shift: The original oscillation signal ΔP(t) is shifted forward by φ_comp phase to obtain the compensated oscillation power ΔP_comp(t).

[0056] In this embodiment, the abstract phase offset difference is converted into an equivalent delay with a unified time dimension by combining the current oscillation frequency. This transforms phase lag into a quantifiable time delay parameter, establishing a conversion bridge between phase deviation and lead compensation angle, providing a unified calculation benchmark for subsequent accurate calculation of the compensation angle. The required phase compensation amount is calculated by inversely solving the link equivalent delay and the dominant oscillation frequency. The compensation angle size is precisely matched with the degree of lag across the entire link and the oscillation frequency, completely offsetting the timing offset caused by the entire path and avoiding undercompensation or overcompensation. The calculated lead compensation angle is superimposed on the original oscillation signal to complete phase correction, ensuring that the phase of the final oscillation signal is completely synchronized with the actual active power oscillation timing of the power grid. This eliminates the negative damping defect caused by phase mismatch, preventing the damping adjustment signal from amplifying oscillations in the reverse direction, and ensuring that the subsequently generated control commands can positively suppress power grid oscillations. Dynamic phase compensation across the entire link is achieved through external step and frequency sweep online identification.

[0057] After completing the accurate phase correction of the oscillation signal, in order to solve the problem of poor adaptability of fixed gain and inability to adapt to the dynamic oscillation conditions of the power grid, this invention designs a segmented adaptive gain matching algorithm based on the oscillation attenuation characteristics to realize the on-demand adjustment of damping force.

[0058] In one possible implementation, the real-time gain matching coefficient is calculated based on the oscillation envelope of the original oscillation power component, including: setting an initial gain matching coefficient according to the oscillation frequency band type; calculating the decay time constant corresponding to the oscillation envelope of the original oscillation power component within a preset number of dominant oscillation cycles; adaptively adjusting the initial gain matching coefficient based on the decay time constant, a first threshold value, and a second threshold value, combined with a preset adjustment step size, upper gain limit, and lower gain limit, to obtain the real-time gain matching coefficient; the second threshold value is less than the first threshold value; wherein, when the decay time constant is greater than the first threshold value, the real-time gain matching coefficient is increased sequentially in each control cycle; when the decay time constant is less than the second threshold value, the real-time gain matching coefficient is decreased sequentially in each control cycle; when the decay time constant is greater than or equal to the second threshold value and less than or equal to the first threshold value, the real-time gain matching coefficient remains unchanged.

[0059] In some embodiments, the oscillation band type refers to different frequency intervals divided by the low-frequency oscillation of the power grid, and the oscillation damping characteristics of different frequency bands differ. The initial gain matching coefficient is a reference damping gain pre-set for the corresponding oscillation band, and is the initial reference value for adaptive adjustment. The dominant oscillation period is the complete oscillation period with the largest amplitude and the dominant effect in the current active power oscillation waveform. The decay time constant is a characteristic parameter obtained by fitting the oscillation envelope; the larger the value, the slower the oscillation decay and the higher the risk of divergence; the smaller the value, the faster the oscillation convergence speed. The first threshold value and the second threshold value are two-level judgment boundary values ​​that distinguish the degree of oscillation convergence.

[0060] In practical implementation, the present invention configures the preferred engineering parameters to achieve practical application: 1) Initial value assignment: Based on the oscillation frequency band selection, the initial value for low-frequency oscillation is preferably 0.3~0.5, and the initial value for subsynchronous oscillation is preferably 0.2~0.3; 2) Evaluation index: Using 10 dominant oscillation periods as a sliding statistical window, solve for the decay time constant T of the envelope of ΔP(t); 3) Threshold parameters: Typical values ​​in the embodiments: T1 preferred range 2.5~3.5s, typical value 3s; T2 preferred range 0.8~1.2s, typical value 1s; The claims only record the first threshold value and the second threshold value, and do not limit the specific values; 4) Adaptive Iteration: The preferred step size is 0.03~0.08, with a typical step size ΔK=0.05; the lower limit of the gain constraint is 0.08~0.15 (typically 0.1), and the upper limit is 0.9~1.1 (typically 1.0). Operating condition judgment logic: T > T1: K_damp = K_damp + ΔK per control cycle, and will not be adjusted upward after reaching the upper limit; T < T2: K_damp = K_damp - ΔK per control cycle, and will not be adjusted downward after reaching the lower limit; T2 ≤ T ≤ T1: K_damp remains unchanged at its current value.

[0061] In this embodiment, a suitable reference gain is configured for oscillations in different frequency ranges. The inherent damping characteristics of oscillations in different frequency bands are distinguished, providing an initial reference that fits the frequency band characteristics for adaptive adjustment. This avoids adaptation deviations caused by a uniform initial gain and improves the adaptability of the basic damping adjustment. Multiple dominant oscillation waveforms are extracted to fit the oscillation envelope. The decay time constant is quantitatively solved through the envelope curve, accurately characterizing the speed of oscillation convergence and divergence. Visually perceptible waveform changes are transformed into quantitative indicators that can be used for logical judgment, providing a reliable basis for adaptive gain adjustment. A two-level threshold segmented adjustment logic is constructed, combined with fixed adjustment step size and upper and lower gain limits, to complete dynamic correction based on the initial gain. The upper and lower limits lock the gain adjustment range, preventing excessive gain from causing drastic power fluctuations and insufficient gain from losing suppression effect, ensuring the gain adjustment process is safe and controllable, and outputting a real-time gain that fits the current oscillation state. Specifically, as oscillations decay slowly and tend to diverge, the damping gain is increased cycle by cycle to strengthen oscillation suppression, quickly suppressing continuously deteriorating active power oscillations and preventing grid instability caused by oscillation divergence. The oscillation converges rapidly, gradually reducing the damping gain to avoid frequent active power adjustments caused by sustained high gain, thus improving converter operational stability and reducing unnecessary power fluctuations. The oscillation convergence speed is moderate, and the operating conditions are stable, maintaining a constant current gain. This balances oscillation suppression with stable unit operation, eliminating the need for frequent gain adjustments and reducing the operational load on the unit. Adaptive gain matching is achieved through the oscillation decay rate. Based on the decay time constant of the oscillation power envelope within a preset time window, the gain matching coefficient is adaptively adjusted against preset first and second threshold values ​​to obtain a real-time dynamic gain matching coefficient.

[0062] After obtaining the compensated oscillation power component and the real-time adaptive gain, in order to avoid equipment damage and secondary disturbances to the power grid caused by sudden changes in damping command power and amplitude exceeding limits, this invention adds multiple safety constraint logics to generate standardized and highly secure final control commands.

[0063] In one possible implementation, a control command is generated based on the compensated oscillation power component and the real-time gain matching coefficient, including: multiplying the compensated oscillation power component and the real-time gain matching coefficient to obtain the original damping adjustment amount; performing amplitude limiting and rate of change limiting on the original damping adjustment amount to obtain the processed damping adjustment amount; and using the processed damping adjustment amount as the control command.

[0064] In some embodiments, the original damping adjustment is the basic active power correction value obtained by multiplying the phase-corrected oscillation signal by the adaptive gain; it is the original power adjustment increment without safety constraints. Amplitude limiting pre-sets the maximum and minimum boundaries of the damping adjustment to restrict the amplitude of a single power adjustment and prevent excessive power in a single adjustment. Rate of change limiting restricts the rate of increase or decrease of the damping adjustment within a single control cycle, constraining the speed of power adjustment and avoiding sudden power fluctuations. The processed damping adjustment is a power correction that meets the requirements for safe unit operation after being constrained by both amplitude and rate of change.

[0065] In practical implementation, after applying amplitude and rate-of-change limiting processing to the power reference value correction, it is superimposed onto the active power reference value external interface of the new energy converter. This achieves additional damping control by correcting the converter's active power setpoint. This invention achieves oscillation suppression by constructing damping power in reverse. The specific formula for generating the power reference value correction is as follows: In the formula, ΔP_comp(t) is the oscillation power component after phase compensation, K_damp is the dynamic gain matching coefficient, and the negative sign reverses to construct the damping power; after generation, when the amplitude is limited, the amplitude shall not exceed the rated power of the converter by 10%, and the power change rate shall be ≤ 5% of the rated power / second.

[0066] In this embodiment, the phase-synchronized oscillation waveform is coupled with adaptive damping gain to convert the oscillation signal into an active power adjustment amount of corresponding strength. This ensures that the power correction amplitude is precisely matched with the current oscillation severity, enabling on-demand output of damping adjustment force. Amplitude limiting constrains the maximum amplitude of a single power adjustment to prevent large power surges from damaging the new energy converter equipment. Rate of change limiting slows down the abrupt change in power adjustment, avoiding secondary disturbances to bus voltage and frequency caused by drastic fluctuations in active power. Dual limiting forms a double-layer safety constraint, balancing oscillation suppression effectiveness with the safety of unit and grid operation. The power correction amount after safety constraints is standardized into an additional control command that can be directly issued, adapting to the signal interaction interface between external devices and the converter controller. No modification to the converter's underlying program is required; additional damping adjustment can be completed simply by superimposing the active power increment, achieving non-intrusive oscillation suppression.

[0067] To further enhance the operational safety of the device and prevent oscillations and grid instability caused by abnormal damping control, this invention adds abnormal operating condition identification, smooth interlocking, and self-recovery protection mechanisms to the conventional damping control logic.

[0068] In one possible implementation, after implementing additional damping control, the method further includes: detecting the oscillation peak value and the oscillation envelope fitting slope within a preset time window; when the oscillation peak value is greater than a preset proportional threshold and the oscillation envelope fitting slope is positive within a preset time, divergent oscillation is determined to occur, the damping correction amount in the control command is smoothly reduced to zero according to the preset slope and the control output is locked, and after a delay, the real-time gain matching coefficient is reduced and control is re-engaged; if divergent oscillation is detected again after re-engaging control, the control function is permanently locked and an alarm signal is output.

[0069] In some embodiments, the preset duration window is a pre-defined continuous sliding detection period used to continuously collect oscillation waveform data within a certain period, serving as the data carrier for judging divergent oscillations. The oscillation peak value is the maximum amplitude of the original active power oscillation power component waveform within the window, characterizing the instantaneous intensity of the current oscillation. The oscillation envelope fitting slope is the slope value obtained by linearly fitting the oscillation amplitude envelope curve; a slope greater than 0 indicates that the oscillation amplitude is continuously increasing, showing a divergent trend; a slope less than 0 indicates that the oscillation amplitude is continuously decreasing, showing a convergent trend. The preset proportional threshold is the threshold for judging the oscillation peak value, representing the minimum amplitude standard for the oscillation intensity to reach the dangerous range. Divergent oscillation is a dangerous oscillation condition where the active power oscillation amplitude continuously increases, gradually deteriorating grid stability. The damping correction is the additional active power regulation increment sent to the converter. Smooth zeroing is the gradual reduction of the damping correction to 0 according to a fixed slope without instantaneously cutting off the damping command. The lockout control output temporarily stops sending damping control commands and suspends the additional damping adjustment. The permanent lockout control function completely shuts down the entire additional damping adjustment algorithm, and no longer generates or outputs damping control commands.

[0070] In the specific implementation process, after the damping is put into operation, the change in the oscillation amplitude of the grid connection point is monitored in real time. When a positive feedback divergent oscillation is detected, the power reference value correction is output to smooth out the blockade. A dual criterion is set to identify divergent oscillation: ① The oscillation peak value is greater than the preset proportion of the baseline value before the operation within a fixed time window (10 oscillation cycles); ② The slope of the oscillation envelope fitting is continuously positive for multiple consecutive cycles; after triggering, the correction is smoothly returned to zero according to the fixed slope, the output is blocked, and the gain is automatically reduced and retried after a delay. A second abnormality will result in a permanent blockade alarm.

[0071] In this embodiment, two types of characteristic quantities are simultaneously collected: oscillation amplitude and intensity, and oscillation amplitude change trend. This allows for comprehensive monitoring of the oscillation state from both the magnitude and development trend dimensions. Relying solely on a single peak value cannot distinguish between convergence and divergence; combining these two factors significantly reduces the probability of missed or false detections of divergent oscillations. A dual-condition approach of peak value exceeding limits and sustained positive slope is used to determine divergent oscillations, avoiding false triggering of protection systems caused by instantaneous waveform fluctuations. Smoothing the zero-damping correction amount instead of directly cutting off the output avoids secondary impacts on the converter and grid caused by sudden changes in active power. Temporarily blocking the output cut-off failure damping adjustment function prevents erroneous control commands from further exacerbating the oscillation. A delayed gain reduction followed by a retry preserves the possibility of control recovery while ensuring grid safety, eliminating the need for direct shutdown and improving the device's continuous operation capability. Secondary divergence indicates that the current damping adjustment strategy has completely failed; the permanent blocking function completely eliminates the significant risk of sustained negative damping exacerbating grid instability. Simultaneously output alarm signals to promptly notify operation and maintenance personnel to conduct on-site inspections of station and equipment faults, ensuring the safe operation of new energy power stations and AC power grids from both proactive protection and operation and maintenance early warning dimensions.

[0072] For multi-unit renewable energy power plant scenarios, independent damping control of a single unit is prone to problems such as adjustment imbalance, mutual interference, and induction of secondary oscillations. In order to achieve precise and coordinated adjustment of the entire station, this invention designs a multi-unit instruction intelligent allocation logic based on the remaining capacity of the units.

[0073] In one possible implementation, after implementing additional damping control, the method further includes: calculating the remaining available capacity of each converter based on its rated power and current operating power; and allocating the damping correction amount in the control command based on the remaining available capacity of each converter.

[0074] In some embodiments, the remaining available capacity is the additional active power margin that a single converter can adjust upwards or downwards, equal to the difference between the rated power and the current operating power, representing the damping regulation margin that the unit can currently handle. Command allocation is performed by dividing and distributing the total damping correction into multiple independent adjustment increments according to the proportion of the remaining active power margin of each converter, matching the regulation capacity of each unit.

[0075] In the specific implementation process, the main control external device collects the electrical quantities of the common grid connection point and calculates the total global correction amount ΔP_total for the entire station; the formula for calculating the remaining available capacity of a single converter is: ΔP_avail_i=P_rated_i-P_current_i, where P_rated_i is the rated power of the i-th renewable energy converter, and P_current_i is the current real-time active power of the i-th renewable energy converter. The formula for calculating the single-unit allocation command is: ΔP_ref_i=ΔP_total×ΔP_avail_i / ∑ΔP_avail_j, where ΔP_total is the total damping correction amount of the station, and ∑ΔP_avail_j is the sum of the remaining capacity of all adjustable converters in the station. If the remaining capacity is 0, the unit does not share the damping power.

[0076] In this embodiment, based on the rated capacity and real-time output of the generating units, the power margin that each converter can currently participate in damping regulation is precisely quantified. This distinguishes the regulation capacity of fully loaded and lightly loaded units, providing a quantitative calculation basis for the reasonable allocation of subsequent damping commands and avoiding exceeding the unit's power regulation limits during allocation. The total damping regulation is distributed according to the proportion of each unit's active power margin. Lightly loaded converters with large remaining capacity undertake more damping regulation tasks, while fully loaded units receive less or no regulation. This balances the regulation load of multiple converters, preventing overload of a single unit from triggering power limiting protection, fully utilizing the regulation resources of all units in the power station, and improving the coordinated regulation capability of the entire new energy power station in suppressing oscillations.

[0077] This invention employs a non-intrusive, end-to-end technical approach, encompassing oscillation characteristic analysis, dynamic signal phase compensation, adaptive gain matching, damping command generation, external port superposition of given values, closed-loop effect evaluation, parameter self-tuning, and safety interlocking. External hardware locally acquires external electrical quantities such as voltage and current at the grid connection point. Oscillation power components are extracted through adaptive bandpass filtering. Based on small external test signals, the phase lag of the entire system is identified online, and proactive phase lead compensation is performed. The gain matching coefficient is then dynamically tuned based on the oscillation decay rate. These two parameters are coupled to calculate the correction amount for the active power reference value. This correction amount, after being double-limited by amplitude and rate of change, is superimposed onto the original given value through the converter's active power reference external interface. After implementation, the oscillation convergence effect is monitored in real time, and phase and gain parameters are adaptively fine-tuned online. In cases of abnormal divergence, the output is automatically smoothed and interlocked. In multi-unit scenarios at the power station, the global damping command is calculated by the main control external device, and the damping power is weighted and allocated among each converter according to its remaining available capacity. It is executed by an additional damping control device that is independently attached to the outside of the new energy converter, and does not acquire the internal control parameters of the power outer loop and current inner loop of the new energy converter throughout the process.

[0078] This invention overcomes the shortcomings of existing built-in modifications that rely on manufacturers to open low-level permissions and external solutions that are difficult to adapt to phase / amplitude. Without modifying the converter's internal control logic, obtaining the converter's inner and outer loop control parameters, or opening the low-level command interface, it relies on external independent hardware to autonomously generate active power correction damping commands based on measured electrical quantities at the grid connection point. This achieves an equivalent PSS additional damping function, reducing the cost of oscillation control and modification of existing renewable energy power plants, improving oscillation suppression response speed and adaptability to all operating conditions, and simultaneously providing multi-level safety protection to prevent devices from inducing new oscillations.

[0079] This invention is a non-invasive and highly versatile retrofit, requiring no open-source parameters or source code from the converter manufacturer. It utilizes only the standard active power reference interface provided with the converter, eliminating the need for disassembly and modification of existing wind and solar converters. On-site construction is convenient, significantly reducing the cost of oscillation mitigation and retrofitting at power plants. Multi-layered protection, including command limiting, positive feedback smooth interlocking, hardware watchdog, and gain reduction self-recovery, prevents the device itself from becoming a source of grid disturbance. Multiple units share damping power based on their remaining capacity, ensuring unified global oscillation judgment and preventing malfunctions, mutual interference, and the induction of new oscillations caused by independent damping control of multiple converters at the power plant.

[0080] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0081] The above embodiments are in Figure 2 Based on the method shown, each step is discussed in detail. To facilitate understanding of the complete execution process, the overall method flow is described below with reference to an example. Figure 3 A schematic diagram of the additional damping control method for externally mounted new energy vehicles.

[0082] Example 1: Oscillation Threshold Triggering and Lockout Logic Example The preferred triggering thresholds for the fixed configuration engineering of this invention are: a preset oscillation quantity threshold of 2% of the rated power of the converter, and a preset oscillation period threshold of 4 oscillation periods, achieving precise triggering under three operating conditions: 1. Steady-state operation: The active power fluctuation amplitude is only 0.8% of the rated power, which is less than 2% of the preset oscillation threshold. It is directly judged as steady-state operation, the damping correction is forced to zero, and no damping calculation or output is initiated. 2. Instantaneous disturbance condition: If the amplitude of a single impact fluctuation reaches 2.5% of the rated power, but only lasts for 2 cycles, and does not reach the preset oscillation threshold of 4 cycles, it is judged as a random disturbance, and the damped output is blocked to avoid false triggering. 3. Effective oscillation condition: The active power oscillation amplitude is 3.2% of the rated power, and the oscillation is continuous and stable for 5 cycles. At the same time, the double threshold conditions are met. It is judged as a continuous power oscillation of the power grid, and the entire process of filtering analysis, phase compensation, gain adaptation, and damping correction output is officially started.

[0083] To verify the full-process adaptability and control accuracy of this invention in low-frequency oscillation scenarios, a low-frequency oscillation condition of a single photovoltaic unit was constructed, and the complete algorithm calculation process was replicated as follows: Example 2: Complete calculation of a single 1MW photovoltaic inverter under 0.5Hz low-frequency oscillation condition (low-frequency scenario, f_osc=0.5Hz) 1) Data acquisition: Three-phase voltage U and current I at the grid connection point; real-time calculation of P_(t); active power exhibits a periodic power oscillation of 0.5Hz. 2) Oscillation determination and filtering configuration: The oscillation amplitude is 3% of the rated power, and the continuous oscillation lasts for 6 cycles. If the double threshold is exceeded, the oscillation is determined to be effective. In the low-frequency scenario, the bandpass center is 0.5Hz, the upper and lower limits are 0.4Hz / 0.6Hz, the fourth order is Q=10, and the original oscillation ΔP_(t) is obtained after filtering out the steady-state power. 3) Phase compensation: The offline calibration base delay τ = 0.2s; a small-amplitude frequency sweep test is performed every 30 minutes, and the measured total system lag at 0.5Hz is Δθ = 36° = 0.628rad; the equivalent delay τ_new = 0.628 / (2×3.14×0.5) = 0.2s is converted, and the lead compensation angle φ_comp = 2×3.14×0.5×0.2 = 0.628rad (36°) is calculated; the original oscillation signal ΔP_(t) is led by 36° to obtain the synchronous compensation oscillation signal ΔP_comp(t); 4) Gain tuning: Initially K_damp=0.4 for low-frequency operation; statistically, the decay time constant T=3.8s>T1=3s within 10 oscillation cycles (20s), and adjust it to K_damp=0.45 in steps of 0.05. 5) Damping command generation (correction amount): ΔP_ref=-0.45×ΔP_comp(t), amplitude limit ≤100kW (rated 1MW×10%), rate of change ≤50kW / s; 6) Superposition: The damping correction ΔPref after the limit is superimposed on the original active power input P_ref0 of the inverter; after the input is put into operation, the oscillation decay time T stabilizes in the range of 1~3s, K_damp no longer changes, and the oscillation gradually converges; 7) Oscillation disappearance lockout: When the oscillation amplitude drops below 2% of the rated power and there is no obvious oscillation for three consecutive cycles, the device automatically locks out the damped output and returns to the steady-state monitoring state.

[0084] To verify the adaptability of this invention to subsynchronous oscillation scenarios, a full-process calculation was performed for the high-frequency subsynchronous oscillation condition of wind turbines to verify the multi-frequency band adaptability of the algorithm: Example 3: Calculation of 2MW wind turbine converter under 15Hz subsynchronous oscillation condition (subsynchronous scenario, f_osc=15Hz) 1) Oscillation judgment: If the oscillation amplitude is 2.8% of the rated power and the continuous stable oscillation lasts for 5 cycles, satisfying the double threshold, damping control will be activated; 2) Adaptive filtering parameter configuration: subsynchronous oscillation, center frequency 15Hz, upper and lower limits 14.5Hz / 15.5Hz, 3rd order bandpass, quality factor Q=8, extract subsynchronous oscillation component ΔP(t); 3) High-frequency phase identification and compensation: The total lag at 15Hz was measured to be Δθ = 270° = 4.71 rad, and the equivalent delay τ_new = 4.71 / (2×3.14×15) = 0.05s was calculated. The lead compensation angle φ_comp = 2×3.14×15×0.05 = 4.71 rad was calculated. 4) Adaptive gain adjustment: Initially, K_damp=0.25 for subsynchronization; after damping is applied, the oscillation decays rapidly at T=0.7s<T2=1s, and is adjusted down by 0.05 each cycle to K_damp=0.2, with moderate damping and no over-adjustment; 5) Correction limit: For a single unit rated at 2MW, the correction range for a single unit is ≤200kW.

[0085] To visually demonstrate the dynamic adaptation effect of the gain adaptive adjustment of this invention, the logic of dynamic iterative gain adjustment is demonstrated for four typical oscillation conditions: Example 4: K_damp Adaptive Dynamic Adjustment Demonstration Configure core parameters: T1=3s (adjustable 2.5~3.5s), T2=1s (adjustable 0.8~1.2s), step size 0.05 (adjustable 0.03~0.08), Kdamp gain upper limit 1.0, gain lower limit 0.1. The adaptive adjustment effect for four typical operating conditions is as follows: 1. Operating condition 1: Effective oscillation condition, oscillation decay T=4.2s>3s: K increases from 0.3→0.35→0.4……until T falls back to the 1~3s range and stops increasing; 2. Operating Condition 2: Effective oscillation condition, oscillation decay T = 0.6s < 1s: K changes from 0.4 → 0.35 → 0.3... until T enters a reasonable range and stops decreasing; 3. Operating condition 3: Effective oscillation condition, T=2.2s, K remains unchanged at its current value; 4. Operating Condition 4: Oscillation disappears, trigger threshold is not met, K_damp freezes, and damping output returns to zero.

[0086] To verify the reliability of the abnormal operating condition protection mechanism of this invention, a fault scenario of oscillation divergence after damping is activated is simulated to demonstrate the protection, self-recovery, and interlocking logic: Example 5: Practical Case Study of Positive Feedback Anomaly Lockout + Self-Recovery Parameter mismatch of a certain photovoltaic unit caused the oscillation amplitude to rise continuously after damping was applied, with the envelope slope being positive for six consecutive cycles, triggering positive feedback protection. 1. Immediately stop the K_damp and ΔP_ref operations and updates; 2. The current output ΔP_ref decays smoothly to zero at 80% per second, without any sudden power surges impacting the DC bus; 3. After a 5-minute lockout delay, the system automatically halves K_damp to 50% of its original value and retryes; after 10 minutes of low gain input, the oscillation converges and the gain is gradually restored to the optimal value in segments; if the retry fails again, the device is permanently locked out and a local audible and visual alarm is triggered.

[0087] To verify the coordinated damping control effect of multi-unit power plants, a scenario with multiple photovoltaic units connected to the grid was built to demonstrate the precise adjustment logic of capacity-weighted allocation: Example 6: Multi-unit coordinated damping control of a 10-unit 1MW photovoltaic inverter power station The additional damping control device first performs a global oscillation judgment: the oscillation amplitude at the grid connection point is 3.5% of the rated power and there are 6 consecutive oscillation cycles, which meets the dual trigger threshold. The global damping calculation is then started, and the total global damping correction amount for the entire station is ΔP_total=500kW. The rated power of a single unit is P_rated = 1MW, and the current output power of each unit is: P1 = 800kW, P2 = 500kW...P10 = 300kW; The remaining capacity of a single unit is ΔP_avail_i = 1000kW - Pcurrent_i, and the total remaining capacity is summed as ∑ΔP_avail = 4200kW. Unit 1 has 200kW remaining, and the allocation instruction ΔP_ref1 = 500 × (200 / 4200) ≈ 23.8kW; the remaining capacity of the fully loaded unit is 0, and the damping allocation of this unit is 0kW; if the total remaining capacity of the entire station is < ΔP_total, then the capacity will be limited according to the total remaining capacity and an insufficient capacity alarm will be sent. If the grid connection point oscillates and falls back, failing to meet the trigger threshold, all units in the entire station will synchronously block the damping output.

[0088] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0089] Figure 4A schematic diagram of the external renewable energy auxiliary damping control device provided in an embodiment of the present invention is shown. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below: like Figure 4 As shown, the external new energy auxiliary damping control device 4 includes: The signal acquisition module 41 is used to acquire the operating data of the grid connection point of the new energy converter to be controlled; the operating data includes real-time active power, bus voltage and grid connection current; The core processing module 42 is used to calculate the active power oscillation and analyze the oscillation period based on the operating data. It determines the effective oscillation based on a dual threshold. When effective oscillation exists, it extracts the original oscillation power component from the real-time active power. It identifies the phase lag of the entire link based on the original oscillation power component and performs phase compensation on the original oscillation power component based on the phase lag to obtain the compensated oscillation power component. It calculates the real-time gain matching coefficient based on the oscillation envelope of the original oscillation power component. It generates control commands based on the compensated oscillation power component and the real-time gain matching coefficient, and sends the control commands to the new energy converter to realize additional damping control.

[0090] In practical implementation, the external new energy auxiliary damping control device comprises five main internal functional modules (power supply module, human-machine interaction module, core processing module, signal acquisition module, and output module). The specific functions of each sub-hardware module are as follows: Signal acquisition module: Used for real-time acquisition of electrical quantities at the grid connection point of the new energy converter. Specifically, it includes voltage transformer and current transformer interfaces, supporting analog or digital input. The acquired signals include at least three-phase voltage and three-phase current at the grid connection point. An external PT / CT is connected to acquire the three-phase analog voltage and current signals at the grid connection point. Core processor module: Equipped with a DSP / FPGA chip, it runs any of the aforementioned external additional damping control algorithms to complete oscillation amplitude and period threshold determination, oscillation extraction, phase identification, gain adaptation, correction calculation, and safety logic determination. Output module: Used to output the calculated power reference value correction to the active power reference value interface of the new energy converter, supporting analog output or communication output. Optional 4~20mA analog output or digital communication can be used to write to the converter's active power reference register; Human-computer interaction module: display screen + buttons, showing oscillation frequency, real-time gain, and device operating status; Power module: Supports AC220V and DC110V power supply; Independent hardware watchdog protection circuit: The output circuit is cut off by hardware when the main processor malfunctions.

[0091] Figure 5This is a schematic diagram of an electronic device provided in an embodiment of the present invention. For example... Figure 5 As shown, the electronic device 5 of this embodiment includes a processor 50 and a memory 51. The memory 51 stores a computer program 52. When the processor 50 executes the computer program 52, it implements the steps in the various method embodiments described above. Alternatively, when the processor 50 executes the computer program 52, it implements the functions of each module / unit in the various device embodiments described above.

[0092] For example, computer program 52 may be divided into one or more modules / units, which are stored in memory 51 and executed by processor 50 to complete the present invention. The one or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of computer program 52 in electronic device 5.

[0093] Electronic device 5 may include, but is not limited to, processor 50 and memory 51. Those skilled in the art will understand that... Figure 5 This is merely an example of electronic device 5 and does not constitute a limitation on electronic device 5. It may include more or fewer components than shown, or combine certain components, or different components. For example, electronic device 5 may also include input / output devices, network access devices, buses, etc.

[0094] For the sake of simplicity and clarity, only the above-described functional modules / units are used as examples. In practical applications, the functions described above can be assigned to different functional modules / units as needed. These modules / units can be implemented in hardware, software, or a combination of both.

[0095] In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not detailed or described in a particular embodiment can be referred to in the relevant descriptions of other embodiments. Unless otherwise specified or in conflict with logic, the terminology and / or descriptions between different embodiments are consistent and can be referenced interchangeably. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0096] 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, and should all be included within the protection scope of the present invention.

Claims

1. A method for controlling the additional damping of an externally mounted new energy source, characterized in that, include: Acquire the operating data of the grid connection point of the new energy converter to be controlled; wherein, the operating data includes real-time active power, bus voltage and grid connection current; The active power oscillation is calculated based on the operating data and the oscillation period is analyzed. Effective oscillation is determined based on a dual threshold. When effective oscillation exists, the original oscillation power component is extracted from the real-time active power. The phase lag of the entire link is identified based on the original oscillation power component, and the phase lag is compensated for based on the original oscillation power component to obtain the compensated oscillation power component. Calculate the real-time gain matching coefficient based on the oscillation envelope of the original oscillation power component; A control command is generated based on the compensated oscillation power component and the real-time gain matching coefficient, and the control command is sent to the new energy converter to achieve additional damping control.

2. The externally mounted new energy additional damping control method according to claim 1, characterized in that, The step of calculating the active power oscillation based on the operating data and analyzing the oscillation period, and determining valid oscillations based on a dual threshold, includes: The active oscillation time-domain waveform is extracted based on the real-time active power. Within a preset window, the oscillation amplitude is calculated based on the peak and valley values ​​of the active power oscillation time-domain waveform, and is used as the active power oscillation amount. Based on the active oscillation time-domain waveform, determine the complete waveform of a single oscillation; The number of oscillation periods is determined based on the complete waveform of the single oscillation. If the active power oscillation is greater than or equal to a preset oscillation threshold, and the number of oscillation cycles is greater than or equal to a preset oscillation cycle threshold, then a valid oscillation is determined to exist.

3. The external new energy additional damping control method according to claim 1, characterized in that, The step of identifying the phase lag of the entire link based on the original oscillation power component includes: Based on the original oscillation power components, determine the phase timing curves of the original oscillation power components and their feedback oscillation power; The phase lag is calculated by taking the phase difference between the original oscillation power component and the feedback oscillation power at the same moment.

4. The externally mounted new energy additional damping control method according to claim 3, characterized in that, The step of performing phase compensation on the original oscillation power component based on the phase lag to obtain the compensated oscillation power component includes: Calculate the equivalent delay based on the phase lag and center frequency; Calculate the lead compensation angle based on the equivalent delay and the center frequency; The compensated oscillation power component is determined based on the original oscillation power component and the lead compensation angle.

5. The externally mounted new energy additional damping control method according to claim 1, characterized in that, The step of calculating the real-time gain matching coefficient based on the oscillation envelope of the original oscillation power component includes: Set the initial gain matching coefficient according to the oscillation frequency band type; Within a preset number of dominant oscillation periods, calculate the decay time constant corresponding to the oscillation envelope of the original oscillation power component; Based on the decay time constant, the first threshold value, and the second threshold value, combined with the preset adjustment step size, upper gain limit, and lower gain limit, the initial gain matching coefficient is adaptively adjusted to obtain the real-time gain matching coefficient; the second threshold value is less than the first threshold value. Wherein, when the decay time constant is greater than the first threshold value, the real-time gain matching coefficient will be increased sequentially in each control cycle; When the decay time constant is less than the second threshold value, the real-time gain matching coefficient will be reduced sequentially in each control cycle; When the decay time constant is greater than or equal to the second threshold value and less than or equal to the first threshold value, the real-time gain matching coefficient remains unchanged.

6. The externally mounted new energy additional damping control method according to claim 1, characterized in that, The step of generating control commands based on the compensated oscillation power component and the real-time gain matching coefficient includes: The original damping adjustment amount is obtained by multiplying the compensated oscillation power component and the real-time gain matching coefficient. The original damping adjustment amount is subjected to amplitude limiting and rate of change limiting to obtain the processed damping adjustment amount; The processed damping adjustment amount is used as the control command.

7. The external new energy additional damping control method according to claim 1, characterized in that, After implementing additional damping control, the following is also included: Within a preset time window, detect the oscillation peak value and the oscillation envelope fitting slope; When the oscillation peak value is greater than the preset proportional threshold and the oscillation envelope fitting slope is positive within the preset time, it is determined that divergent oscillation has occurred. The damping correction amount in the control command is smoothly reduced to zero according to the preset slope and the control output is locked. After a delay, the real-time gain matching coefficient is reduced and the control is re-entered. If divergent oscillation is detected again after control is re-engaged, the control function will be permanently locked and an alarm signal will be output.

8. The externally mounted new energy additional damping control method according to claim 1, characterized in that, After implementing additional damping control, the following is also included: Calculate the remaining available capacity of each converter based on its rated power and current operating power; Based on the remaining available capacity of each converter, the damping correction amount in the control command is allocated.

9. An externally mounted new energy auxiliary damping control device, characterized in that, include: The signal acquisition module is used to acquire the operating data of the grid connection point of the new energy converter to be controlled; wherein, the operating data includes real-time active power, bus voltage and grid connection current; The core processing module is used to calculate the active power oscillation and analyze the oscillation period based on the operating data, determine the effective oscillation based on dual thresholds, extract the original oscillation power component from the real-time active power when effective oscillation exists, identify the phase lag of the entire link based on the original oscillation power component, and perform phase compensation on the original oscillation power component based on the phase lag to obtain the compensated oscillation power component, calculate the real-time gain matching coefficient based on the oscillation envelope of the original oscillation power component, generate control commands based on the compensated oscillation power component and the real-time gain matching coefficient, and send the control commands to the new energy converter to realize additional damping control.

10. An electronic device, characterized in that, It includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the method as described in any one of claims 1 to 8.

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