Energy storage low-frequency oscillation suppression method based on damping controller and resonance controller

Abstract

The invention discloses an energy storage low-frequency oscillation suppression method based on a damping controller and a resonance controller, particularly relates to the field of low-frequency oscillation suppression, and comprises the following steps: judging the type of low-frequency oscillation, then adaptively selecting and online setting the corresponding damping or resonance controller, and generating compensation power. According to the energy storage low-frequency oscillation suppression method based on the damping controller and the resonance controller, a negative damping oscillation and forced oscillation dual-discrimination access is constructed, so that the type of low-frequency oscillation is effectively identified, and the defect that the effective identification capability of the oscillation type is lacked is overcome; the controller is adaptively selected according to the oscillation type, targeted suppression is applied to different types of oscillation, invalid adjustment of a single control strategy is avoided, resource waste of the energy storage system is reduced, suppression efficiency is improved, service life attenuation of the energy storage device is slowed down, and forced oscillation energy propagation is suppressed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of low-frequency oscillation suppression, and more particularly to a method for suppressing low-frequency oscillation by energy storage based on a damping controller and a resonance controller. BACKGROUND

[0002] With the development of large-scale new energy grid connection and regional grid interconnection, it is necessary to ensure the stable operation of the power system, especially to suppress low-frequency oscillation. In the traditional power system, the power system stabilizer provided by the synchronous generator set is usually relied on to provide damping. The working principle is to suppress the relative swing between rotors by adjusting the excitation of the unit. However, the traditional scheme has significant technical bottlenecks: when the grid structure or working condition changes, the suppression effect of the power system stabilizer will be greatly reduced; for forced power oscillation caused by external periodic disturbance sources, there is no effective suppression means, which leaves a safety hazard.

[0003] To solve the defects of poor adaptability and limited suppression range of the traditional power system stabilizer, the prior art connects a storage device to the key node of the grid and provides an additional damping controller for it to form an active suppression scheme. The required damping power is calculated according to the deviation of the line power, frequency or phase angle, and the storage converter is instructed to execute, directly injecting or absorbing a compensation power opposite to the power oscillation into the grid, thereby effectively suppressing the negative damping oscillation of the system, thus eliminating the dependence on specific generator sets, responding faster and having more significant suppression effect.

[0004] However, in actual use, it still has some disadvantages, such as using a single additional damping control strategy, and due to the lack of effective identification ability of the oscillation type, when encountering forced oscillation caused by external periodic disturbance sources, the controller cannot apply targeted suppression from the root cause; thereby causing the controller to continuously perform invalid power regulation, causing serious waste of energy storage system resources and reducing the overall suppression efficiency; invalid power throughput accelerates the life decay of the energy storage device, increasing the operation and maintenance burden; as the energy of forced oscillation cannot be effectively contained, it can spread in the grid, ultimately posing a direct threat to the safe and stable operation. SUMMARY

[0005] In order to overcome the above-mentioned defects of the prior art, the present application provides a method for suppressing low-frequency oscillation by energy storage based on a damping controller and a resonance controller, which solves the problems raised in the background art by the following scheme.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical scheme: The method for suppressing low-frequency oscillation by energy storage based on a damping controller and a resonance controller comprises: S1: collect a first oscillation signal of a target power grid area, and pre-process the first oscillation signal to obtain a second oscillation signal; S2: perform mode recognition on the second oscillation signal to extract a first oscillation feature of a dominant oscillation mode at a target time, the first oscillation feature at least including an oscillation frequency and a damping ratio; S3: based on the first oscillation feature, distinguish an oscillation type of the dominant oscillation mode, and output a second oscillation feature; S4: according to the second oscillation feature, adaptively select and enable a corresponding controller to generate a suppression power instruction: when the second oscillation feature is a negative damping oscillation, enable a damping controller, and use the first oscillation feature to perform online setting of the damping controller to generate a first suppression instruction for providing positive damping; when the second oscillation feature is a forced oscillation, enable a resonance controller, and use the first oscillation feature to perform frequency locking of the resonance controller to generate a second suppression instruction for offsetting a periodic disturbance; S5: convert the first suppression instruction or the second suppression instruction output by the selected controller into compensation power, and through continuous execution of S1 to S4, perform closed-loop feedback adjustment on the suppression effect of low-frequency oscillation.

[0007] Preferably, in the S2, the first oscillation feature of the dominant oscillation mode at the target time specifically includes: obtaining the oscillation frequency in the first oscillation feature, specifically represented as: , wherein, represents the second oscillation signal at a time point , represents the oscillation amplitude of the th potential oscillation mode, represents the decay factor of the th potential oscillation mode, represents the oscillation frequency of the th potential oscillation mode, represents the phase offset of the th potential oscillation mode.

[0008] Preferably, in the S2, the first oscillation feature of the dominant oscillation mode at the target time specifically further includes: based on the decay factor of the th potential oscillation mode, the damping ratio of the th potential oscillation mode is calculated through the real part and the imaginary part, and is specifically represented as: .

[0009] Preferably, the S3, the second oscillation feature at least includes an oscillation type flag and its corresponding oscillation frequency value; The oscillation type flag is used to trigger the corresponding control path, including a negative damping oscillation discrimination path and a forced oscillation discrimination path; Wherein, when the oscillation type flag is forced oscillation, the second oscillation feature contains the matched disturbance source.

[0010] Preferably, the S3, the discrimination logic of the negative damping oscillation discrimination path, specifically includes: The real-time damping ratio is continuously lower than the preset safety threshold; The oscillation frequency fluctuates within a time window with a preset length of The fluctuation range is less than a preset fluctuation threshold, and the oscillation amplitude presents a continuous growth trend.

[0011] Preferably, the S3, the discrimination logic of the forced oscillation discrimination path, specifically includes: The oscillation frequency matches the frequency in the periodic disturbance source feature frequency library; Analyze and judge the strong correlation between the oscillation phase and the running state of the suspected disturbance source.

[0012] Preferably, the S4, the online setting of the damping controller, specifically includes: According to the difference between the damping ratio in the first oscillation feature and the target damping ratio, the gain of the damping controller is adaptively adjusted; According to the oscillation frequency in the first oscillation feature, the lead time constant and the lag time constant of the damping controller are adaptively calculated and adjusted to provide optimal phase compensation at the current dominant oscillation frequency.

[0013] Preferably, the S4, the frequency locking of the resonance controller, specifically includes: The oscillation frequency in the first oscillation feature is directly set as the center frequency of the resonance controller, so that the resonance controller generates a cancellation signal with the same amplitude and opposite phase as the forced oscillation amplitude.

[0014] The technical effects and advantages of the present application are: 1、The present application realizes fine analysis of the time-frequency domain of the oscillation signal by quantitatively extracting the low-frequency oscillation signal, avoids misjudgment caused by multi-modal interference in traditional methods, and ensures focusing on the oscillation mode with the greatest threat; 2. The present invention realizes effective identification of low-frequency oscillation types by constructing a dual-discrimination path of negatively damped oscillation and forced oscillation, thus overcoming the defect of lack of effective identification capability of oscillation types; 3. The present invention adaptively selects a controller according to the oscillation type and applies targeted suppression to different types of oscillations, thereby avoiding the ineffective adjustment of a single control strategy, reducing the waste of energy storage system resources, improving the suppression efficiency, slowing down the life decay of the energy storage device, and curbing the propagation of forced oscillation energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a block diagram of the steps of a method for energy storage to suppress low-frequency oscillation based on a damping controller and a resonant controller provided in an embodiment of the present application. DETAILED DESCRIPTION

[0016] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] The terms used in the following examples of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification of the present application, the singular expressions "a", "an", "said", "above", "the", and "this" are intended to include plural expressions as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used in the present application refers to and includes any or all possible combinations of one or more of the listed items.

[0018] In the following, the terms "first" and "second" are used for descriptive purposes only and should not be understood to imply or suggest relative importance or implicitly indicate the number of the technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the embodiments of this application, unless otherwise specified, "plurality" means two or more.

[0019] As attached Figure 1 The energy storage method for suppressing low-frequency oscillations based on a damping controller and a resonant controller is shown. By identifying the type of low-frequency oscillation, the corresponding damping or resonant controller is adaptively selected and adjusted online to generate compensation power. The method specifically includes the following steps: S1: collecting a first oscillation signal in a target power grid area, and preprocessing the first oscillation signal to obtain a second oscillation signal; S2: performing mode recognition on the second oscillation signal to extract a first oscillation feature of a dominant oscillation mode at a target time, the first oscillation feature including at least an oscillation frequency and a damping ratio; S3: based on the first oscillation feature, discriminating an oscillation type of the dominant oscillation mode, and outputting a second oscillation feature; S4: according to the second oscillation feature, adaptively selecting and enabling a corresponding controller to generate a suppression power instruction: when the second oscillation feature is a negative damping oscillation, enabling a damping controller, and online tuning the damping controller using the first oscillation feature to generate a first suppression instruction for providing positive damping; when the second oscillation feature is a forced oscillation, enabling a resonance controller, and frequency-locking the resonance controller using the first oscillation feature to generate a second suppression instruction for counteracting a periodic disturbance; S5: converting the first or second suppression instruction output by the selected controller into a compensation power, and through continuously executing S1-S4, performing closed-loop feedback adjustment on the suppression effect of the low-frequency oscillation.

[0020] Specifically, in S1, a phasor measurement unit deployed at a key node in a target power grid region is used to collect a first oscillation signal capable of representing a low-frequency oscillation state in real time, the first oscillation signal being preferably an active power signal of a key tie line or a frequency signal of an important bus, and a pre-processing procedure is performed on the collected first oscillation signal to effectively filter out high-frequency noise, power frequency harmonic interference and outliers in the measurement data, thereby eliminating measurement errors, and the output of the pre-processing procedure, i.e., a second oscillation signal.

[0021] In the embodiment, in terms of the specific implementation of the first oscillation signal collection, the key node is selected to capture and reflect the overall operating state of the target power grid and potential low-frequency oscillation information to the greatest extent, including but not limited to key tie lines connecting different regional power grids, outgoing lines of large power plants, hub substation buses of important load centers, etc.; preferably, the active power signal of the tie line and the frequency signal of the hub substation bus are collected as the first oscillation signal; all deployed phasor measurement units need to strictly follow the IEEE C37.118.1 standard, and high-precision time synchronization is achieved using the global positioning system to ensure that the measurement data from different geographical locations have unified and accurate time scales.

[0022] Further, the first oscillation signal is pre-processed as follows: low-pass filtering, preferably a digital low-pass filter is used in the embodiment, including but not limited to Butterworth, Chebyshev filter, etc., to process the collected first oscillation signal; the frequency band of the first oscillation signal is limited to a low-frequency oscillation frequency band of 0.1-2.5 Hz through low-pass filtering, to determine the irrelevant signals such as high-frequency noise, power frequency and its harmonic components, and subsynchronous oscillation caused by power electronic equipment, communication interference, etc.; noise reduction processing, preferably a wavelet transform noise reduction method or an adaptive Kalman filter is used in the embodiment to process the filtered signal, to distinguish the characteristics of signal and noise in different scales, and by setting a suitable threshold to remove the wavelet coefficients corresponding to noise, the random noise can be smoothed to the greatest extent while the key mutation characteristics in the oscillation waveform are completely retained, thereby significantly improving the signal-to-noise ratio of the signal.

[0023] Further, a verification mechanism is introduced in the pre-processing process of the first oscillation signal to ensure that the output second oscillation signal always meets the high-quality standard, the verification mechanism includes: internal quality verification, real-time time-domain and frequency-domain characteristic analysis is performed on the pre-processed second oscillation signal, and its key quality indicators are calculated, the key quality indicators in the embodiment include but are not limited to signal-to-noise ratio and total harmonic distortion rate, etc.; if the key quality indicators are better than the preset quality threshold, it is determined that the pre-processing is effective; otherwise, if the key quality indicators fail to meet the standard, an alarm log is automatically generated; cooperative cross-verification, the embodiment performs logical judgment based on the consistency of multiple PMU data, that is, by comparing the signals from multiple key nodes with adjacent geographical positions or close electrical connection in real time, when the dynamic characteristics of the key node, including but not limited to dominant frequency, phase change trend, etc., show significant irrelevance with the surrounding signals, it is determined that the node data may have deep-seated abnormalities and corresponding fault-tolerant processing measures such as temporarily excluding the signal, reducing its weight, or triggering a deep diagnosis program are taken.

[0024] Specifically, in S2, the bandwidth of the second oscillation signal output in S1 is limited to a low-frequency oscillation frequency band of 0.1-2.5 Hz, and is converted into a group of core feature parameters capable of quantitatively representing the low-frequency oscillation dynamic characteristics of the target power grid area, the second oscillation signal is processed through a recognition algorithm, thereby extracting the first oscillation feature of the dominant oscillation mode, and the key quantitative indicators represented by the first oscillation feature include at least oscillation frequency and damping ratio.

[0025] In a possible implementation, the mode recognition of the second oscillation signal includes: a preset length of a current time window data sequence of the second oscillation signal as a recognition input; establishing a pattern recognition model and estimating parameters based on the data sequence to obtain a set of potential oscillation modes; screening and verifying the potential oscillation modes, and selecting one with the highest amplitude as a dominant oscillation mode to extract a first oscillation feature.

[0026] It should be noted that the first oscillation feature preferably includes an oscillation frequency, a damping ratio and an oscillation amplitude; the pattern recognition model preferably adopts an adaptive Prony algorithm or a recursive subspace recognition algorithm, the adaptive Prony algorithm adjusts the model order dynamically to attenuate a combination of sinusoidal functions to fit the second oscillation signal, and directly analyzes the damping ratio and the oscillation frequency representing the oscillation attenuation characteristics from the fitting function as the first oscillation feature; the recursive subspace recognition algorithm updates the pattern recognition model recursively to accurately calculate the first oscillation feature by performing eigenvalue decomposition on the recognized system matrix, thereby simultaneously recognizing multiple dominant oscillation modes.

[0027] Further, the oscillation frequency and amplitude in the first oscillation feature are obtained by superimposing a plurality of attenuated sinusoidal functions, specifically represented as: , wherein, represents the second oscillation signal at a time point , represents the oscillation amplitude of the th potential oscillation mode, represents the attenuation factor of the th potential oscillation mode, represents the oscillation frequency of the th potential oscillation mode, represents the phase offset of the th potential oscillation mode; based on the attenuation factor of the th potential oscillation mode , the damping ratio of the th potential oscillation mode is calculated by the real part and the imaginary part, specifically represented as: , wherein, represents the oscillation frequency of the th potential oscillation mode.

[0028] It should be noted that the oscillation amplitude of the th potential oscillation mode reflects the initial strength of the oscillation; the The damping factor of a potential oscillation mode determines whether the oscillation is gradually weakened or continuously grows, and when the oscillation is determined to be gradually weakened, the oscillation amplitude is used as a basis for adaptively setting the gain of an additional damping controller; the The oscillation frequency of a potential oscillation mode Embodies the fast and slow of the oscillation, which is related to the swing frequency of the generator rotor; the The phase offset of a potential oscillation mode Indicates the starting phase of the oscillation.

[0029] Further, the screening and verification of the potential oscillation mode at least includes: eliminating all modes whose oscillation frequency Is not within 0.1 Hz to 2.5 Hz; and eliminating modes whose oscillation amplitude Is lower than that which can be considered as calculation noise or unreasonable in physical meaning; in all valid oscillation modes that pass the screening, according to the oscillation amplitude of each mode The largest amplitude is selected as the dominant oscillation mode that constitutes the main threat.

[0030] Specifically, in S3, based on the first oscillation characteristics including the oscillation frequency, damping ratio and oscillation amplitude extracted in S2, intelligent diagnosis is performed on the dominant oscillation mode in the target power grid region, so as to distinguish between negative damping oscillation caused by deterioration of its own damping characteristics and forced oscillation caused by injection of energy by an external periodic disturbance source, and output a structured second oscillation characteristic, which includes an oscillation type flag bit and a key parameter corresponding to the oscillation type flag bit, i.e. the oscillation frequency and damping ratio when it is determined to be negative damping oscillation, or the oscillation frequency and the matched disturbance source identifier when it is determined to be forced oscillation.

[0031] It should be noted that the step of intelligently distinguishing the oscillation type is realized by executing two parallel discrimination channels based on different physical mechanisms, including a negative damping oscillation discrimination channel for identifying oscillation caused by insufficient self-damping, and a forced oscillation discrimination channel for identifying oscillation caused by an external periodic disturbance source.

[0032] In a possible implementation, the second oscillation characteristic at least includes an oscillation type flag bit and its corresponding oscillation frequency value, the oscillation type flag bit is used to trigger the corresponding control channel, and when the negative damping oscillation discrimination channel is triggered, the discrimination logic thereof includes: the real-time damping ratio Continuously below a preset safety threshold; the preferred safety threshold in this embodiment is preset to 0.03; the oscillation frequency In a preset length The time window remains relatively stable, and its fluctuation range is less than the preset fluctuation threshold. It shows a trend of continuous growth or maintaining at a high level.

[0033] It should be noted that the safety threshold is set based on the minimum requirement for the damping ratio in the power system stability standard to ensure a minimum positive damping margin; if the damping ratio is lower than the safety threshold, it indicates that the current oscillation mode exhibits negative damping characteristics and there is a risk of instability, which requires intervention; the length of the time window is The setting must include at least the oscillation frequency The corresponding 3 to 5 complete cycles are used to ensure that the growth trend of the amplitude and the stability of the frequency can be reliably observed. In this embodiment, for an oscillation of 0.5 Hz, The oscillation frequency is set to at least 6 seconds; The fluctuation threshold is usually set to the oscillation frequency 1% to 2% of the frequency, used to distinguish between forced oscillations with stable frequency and negatively damped oscillations that may drift slightly; for oscillation amplitude The growth trend can be determined by calculating the time window The linear regression slope of the internal oscillation amplitude series is implemented as follows: if the slope is greater than zero and exceeds the minimum growth sensitivity threshold, it is judged to be continuously growing; if the mean of the amplitude series is continuously higher than its baseline amplitude in the steady state by more than 50%, it is judged to be maintained at a high level; the above multiple criteria must be met simultaneously to form the necessary and sufficient conditions for negatively damped oscillation.

[0034] In one possible embodiment, the second oscillation characteristic includes at least an oscillation type flag and its corresponding oscillation frequency value, and the oscillation type flag is used to trigger the corresponding control path. When the forced oscillation judgment path is triggered, the second oscillation characteristic includes a matched disturbance source, and its judgment logic includes: the oscillation frequency is matched with the frequency in a pre-stored periodic disturbance source characteristic frequency library; and the locking or strong correlation relationship between the oscillation phase and the operating state of the suspected disturbance source is analyzed and judged.

[0035] It should be noted that the frequency matching is defined as the identified oscillation frequency The characteristic frequencies of known periodic disturbance sources pre-entered in the database The absolute difference between Smaller than a preset tolerance band , the allowable error band The PMU measurement accuracy, system frequency fluctuation and mode identification algorithm error are considered, and 0.01-0.05 Hz is usually set; the disturbance source can include but is not limited to the operating frequency of a specific variable frequency load, the periodic impact load of a large industrial device, or the shaft torsional vibration frequency of a generator set; the oscillation phase correlation criterion is realized by analyzing the synchronous phasor measurement signals of multiple key nodes in the target power grid, by comparing the phase of the suspected disturbance source access point with the phase of the oscillation signal of the remote observation point, if the phase difference of the two at the oscillation frequency stays stable, that is, the phase is locked; the embodiment preferably quantitatively judges by calculating the coherence coefficient of the two signals near the oscillation frequency point, if the coherence coefficient is continuously higher than 0.9 and the phase difference is stable, it is determined that there is strong correlation.

[0036] Specifically, in S4, the second oscillation characteristic is received and analyzed to adaptively select a suppression technology path, and the core parameters of the selected controller are configured based on the real-time working condition to generate an instruction for suppressing power.

[0037] It should be noted that the adaptive selection of the suppression technology path and the corresponding controller are as follows: when the second oscillation characteristic is determined to be negative damping oscillation, the resonance controller is locked and the damping controller is enabled; when the second oscillation characteristic is determined to be forced oscillation, the damping controller is locked and the resonance controller is enabled.

[0038] In one possible implementation, when the second oscillation characteristic is determined to be negative damping oscillation, the process of online tuning of the damping controller includes: adaptively adjusting the gain of the damping controller according to the difference between the damping ratio in the first oscillation characteristic and the target damping ratio; the greater the damping deficiency ratio difference, that is, the higher the deficiency, the greater the gain setting, so that the controller can provide stronger damping torque; and adaptively calculating and adjusting the lead time constant and the lag time constant of the damping controller according to the oscillation frequency in the first oscillation characteristic to provide optimal phase compensation at the currently dominant oscillation frequency, so that the phase of the final output of the damping controller is exactly opposite to the oscillation mode, thereby generating the maximum positive damping effect.

[0039] It should be noted that the target damping ratio can be pre-set according to the safe operation regulation of the power grid, and is usually a fixed value greater than zero; the preferred target damping ratio of the embodiment is 0.03 or 0.05; the process of self-adaptive adjustment depends on the built-in preset tuning rule library, which contains parameter mapping relationships established based on the phase compensation method, pole placement method or a large amount of offline simulation and online learning data; the adjustment of the gain is used to provide an inhibition strength matched with the degree of damping deficiency, and the adjustment of the lead and lag time constants ensures that the controller can provide accurate phase compensation at the current dominant oscillation frequency point; the preferred target of the embodiment is to make the output inhibition signal and the oscillation mode signal opposite to each other, so as to synthesize the maximum positive damping torque; the damping control preferably adopts a lead-lag compensation network structure with a transfer function; preferably, the tuning process is a continuous dynamic optimization process, and after the damping controller is put into operation, the change of the oscillation mode damping ratio is continuously monitored to form a closed-loop feedback; if the damping ratio is improved and tends to be stable, the gain can be gradually reduced to avoid over-regulation; if the damping effect is not as expected, the time constant can be further optimized or the gain can be moderately increased.

[0040] Further, the transfer function is specifically expressed as: , wherein, is a real-time gain, which is self-adaptively adjusted by the tuning rule library according to the difference between the current damping ratio and the target damping ratio, is a lead time constant, which is calculated online according to the oscillation frequency in the first oscillation characteristic, to ensure that the required lead phase is provided at to make the controller output accurately opposite to the oscillation mode, is a lag time constant, which determines the frequency band width of the phase compensation.

[0041] In a possible implementation, when the second oscillation characteristic is determined to be forced oscillation, the process of frequency locking of the resonance controller includes: directly setting the oscillation frequency in the first oscillation characteristic as the center frequency of the resonance controller, so that the resonance controller generates a cancellation signal with an equal amplitude and an opposite phase to the forced oscillation.

[0042] It should be noted that the resonance controller adopts the structure of a resonance controller based on a second-order generalized integrator or a variant thereof to realize the zero-error tracking and generation of a specific frequency sinusoidal component; the direct setting means that there is an instant and definite mathematical relationship between the oscillation frequency and the center frequency of the resonance controller , that is The effectiveness of the controller is entirely dependent on the accuracy of the oscillation frequency; by frequency locking, the controller accurately captures the frequency component of the forced oscillation, and through its internal closed-loop control, automatically adjusts the amplitude and phase of its output signal, aiming to match the amplitude and phase of the power fluctuation component generated by the detected forced oscillation source at the grid connection point, so as to fundamentally suppress the forced oscillation; preferably, the output amplitude of the resonant controller is not fixed, and in this embodiment, an amplitude control loop is configured, the initial reference value of which is set based on the amplitude of the identified oscillation mode, and is fine-tuned in operation according to the monitored oscillation amplitude to achieve optimal cancellation and avoid over-compensation.

[0043] Specifically, in S5, the command of the suppression power is converted into an actual power command executable by the energy storage converter, and through real-time monitoring of the suppression effect, a closed-loop feedback is formed to dynamically adjust the control state to achieve low-frequency oscillation suppression.

[0044] Further, the process of converting the command of the suppression power into the compensation power includes: dynamically scaling the suppression command generated by the damping controller or the resonant controller according to the rated power capacity of the energy storage and the current operating state parameters, to generate an active power reference increment within a safe range; superimposing the active power reference increment with the power set value for executing other grid services to form a final total active power reference value through a priority coordination algorithm; and sending the total active power reference value to the control layer of the energy storage converter to drive the converter to generate corresponding compensation power.

[0045] It should be noted that the dynamic scaling is used to linearly or nonlinearly map the dimensionless command output by the controller into the current maximum allowable charging and discharging power range, and the scaling coefficient is a linear function represented by the current operating state parameters; the current operating state parameters include but are not limited to the current available capacity, the health state, the temperature parameter, etc.; in this way, it is ensured that the command execution is always within the safe operating boundary, and the device overload and accelerated aging caused by over-power command are fundamentally avoided; the priority coordination algorithm is used to arbitrate possible conflicts between the oscillation suppression command and other grid service commands; the other grid service commands include but are not limited to frequency regulation, peak shaving and valley filling, etc.; by giving the oscillation suppression the highest priority, it is ensured that the suppression power demand can be preferentially and sufficiently met when low-frequency oscillation is detected, and the power commands of other grid service commands are distributed within the remaining capacity after meeting the oscillation suppression demand.

[0046] Further, the closed-loop feedback regulation comprises: continuously monitoring the real-time amplitude of the dominant oscillation mode; comparing the real-time amplitude with a first preset threshold; when the real-time amplitude is suppressed below the first preset threshold, determining the type of the currently input controller, if the currently input controller is a damping controller, gradually reducing the gain of the damping controller until it is completely withdrawn; if the currently input controller is a resonance controller, directly locking the output of the resonance controller to make it stop working immediately; continuously monitoring the real-time amplitude of the dominant oscillation mode; comparing the monitored real-time amplitude with a second preset threshold; when the real-time amplitude exceeds the second preset threshold again, restarting the closed-loop feedback regulation process; otherwise, continuously monitoring the real-time amplitude of the dominant oscillation mode.

[0047] It should be noted that the first preset threshold is a safety threshold value of oscillation suppression, and the setting basis is the maximum oscillation amplitude allowed by the target power grid stable operation; the second preset threshold is equal to or slightly higher than the first preset threshold, so as to prevent the frequent switching of the controller caused by the fluctuation of the measurement signal near the threshold, and further reduce the number of invalid actions of the energy storage; the gain of the damping controller is gradually reduced to avoid the secondary impact caused by the sudden withdrawal of the controller; and the resonance controller is directly locked because the cancellation of the disturbance of a specific frequency has been completed, and there is no need for a gradual reduction process.

[0048] Secondly, in the drawings of the disclosed embodiments, only the structures related to the disclosed embodiments are involved, other structures can be referred to the general design, and the same embodiments and different embodiments of the present application can be combined with each other under the condition of no conflict; Finally, the above only describes the preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for suppressing low-frequency oscillation by energy storage based on a damping controller and a resonance controller, characterized in that: include: S1: collecting a first oscillation signal in a target power grid area, and preprocessing the first oscillation signal to obtain a second oscillation signal; S2: performing pattern recognition on the second oscillation signal to extract a first oscillation feature of a dominant oscillation mode at a target moment, wherein the first oscillation feature includes at least an oscillation frequency and a damping ratio; S3: Based on the first oscillation characteristic, the oscillation type of the dominant oscillation mode is determined, and a second oscillation characteristic is output; S4: According to the second oscillation characteristic, adaptively select and enable a corresponding controller to generate a suppression power instruction: When the second oscillation characteristic is a negative damping oscillation, enabling a damping controller, and performing online tuning on the damping controller using the first oscillation characteristic to generate a first suppression instruction for providing positive damping; When the second oscillation characteristic is a forced oscillation, enabling a resonant controller, and frequency-locking the resonant controller using the first oscillation characteristic to generate a second suppression instruction for offsetting periodic disturbances; S5: Convert the first suppression command or the second suppression command output by the selected controller into compensation power, and perform closed-loop feedback adjustment on the suppression effect of the low-frequency oscillation by continuously executing S1 to S4.

2. The energy storage method for suppressing low-frequency oscillation based on a damping controller and a resonant controller according to claim 1 is characterized in that: The step S2, extracting the first oscillation feature of the dominant oscillation mode at the target moment, specifically includes: Obtaining the oscillation frequency in the first oscillation characteristic is specifically expressed as: ， in, Represented as a time point The second oscillation signal at Expressed as The oscillation amplitude of the potential oscillation mode, Expressed as The attenuation factor of the potential oscillation mode, Expressed as The oscillation frequency of the potential oscillation mode, Expressed as The phase shift of the potential oscillation mode.

3. The energy storage method for suppressing low-frequency oscillation based on a damping controller and a resonant controller according to claim 2 is characterized in that: The step S2, extracting the first oscillation feature of the dominant oscillation mode at the target moment, specifically includes: Based on the The attenuation factor of the potential oscillation mode , calculated by its real and imaginary parts, The damping ratio of the potential oscillation mode , specifically expressed as: 。 4. The energy storage method for suppressing low-frequency oscillation based on a damping controller and a resonant controller according to claim 1 is characterized in that: Said S3, the second oscillation characteristic at least includes an oscillation type flag and its corresponding oscillation frequency value; The oscillation type flag is used to trigger corresponding control paths, including a negative damping oscillation determination path and a forced oscillation determination path; When the oscillation type flag is forced oscillation, the second oscillation feature includes the matched disturbance source.

5. The energy storage method for suppressing low-frequency oscillation based on a damping controller and a resonant controller according to claim 4 is characterized in that: Said S3, the discrimination logic of the negative damped oscillation discrimination path, specifically includes: The real-time damping ratio is continuously lower than the preset safety threshold; The oscillation frequency is set to The fluctuation range within the time window is smaller than the preset fluctuation threshold, and the oscillation amplitude shows a trend of continuous growth.

6. The method for suppressing low-frequency oscillation by energy storage based on a damping controller and a resonant controller according to claim 4, characterized in that: Said S3, the judgment logic of the forced oscillation judgment path, specifically includes: The oscillation frequency matches the frequency in the characteristic frequency library of the periodic disturbance source; Analyze and determine the strong correlation between the oscillation phase and the operating status of the suspected disturbance source.

7. The energy storage method for suppressing low-frequency oscillation based on a damping controller and a resonant controller according to claim 1 is characterized in that: The step S4, performing online tuning on the damping controller, specifically includes: adaptively adjusting a gain of the damping controller according to a difference between the damping ratio in the first oscillation characteristic and a target damping ratio; According to the oscillation frequency in the first oscillation characteristic, the leading time constant and the lagging time constant of the damping controller are adaptively calculated and adjusted to provide optimal phase compensation at the currently dominant oscillation frequency.

8. The energy storage method for suppressing low-frequency oscillation based on a damping controller and a resonant controller according to claim 1 is characterized in that: The step S4 of frequency locking the resonant controller specifically includes: The oscillation frequency in the first oscillation characteristic is directly set as the center frequency of the resonant controller, so that the resonant controller generates a cancellation signal with equal amplitude and opposite phase to the forced oscillation.

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