Power system stabilizer

Abstract

The present application relates to the technical field of power system, and particularly relates to a power system stabilizer, comprising: a wide-frequency oscillation detection component, which is used for filtering out a wide-frequency oscillation component satisfying a preset frequency range from a power grid signal; a wide-frequency amplitude-phase adjustment component, which is used for carrying out amplitude and phase correction on the wide-frequency oscillation component under a preset oscillation suppression condition, to obtain a corrected wide-frequency oscillation component; and an output adaptation component, which is used for generating a control signal of a target converter according to the corrected wide-frequency oscillation component, and controlling the target converter according to the control signal, so as to solve the problems of limited frequency band and poor adaptability of the suppression method of wide-frequency oscillation in the related art, and improve the wide-frequency damping capability and the general access performance of the converter.

Description

Technical Field

[0001] This invention relates to the field of power system technology, and in particular to a power system stabilizer. Background Technology

[0002] The new power system is characterized by a high proportion of new energy sources and a high proportion of power electronic equipment. Traditional synchronous generators, wind and solar power, flexible AC / DC equipment, and electronic load terminals are interconnected through a complex power network, resulting in multi-timescale interactions involving mechanical, electrical, magnetic, and control systems, which in turn cause frequency variations from numerical to numerical. Up to number Wide-band oscillation (WBO) is becoming a new type of stability problem and a major technical challenge that restricts the development of the power industry. Wide-band oscillation can affect power quality and cause unit tripping, as well as cause large-scale grid disconnection and equipment damage of new energy units. It may also cause a complete shutdown of thermal power plants, resulting in regional or even global safety and stability accidents.

[0003] In related technologies, power system stabilizers (PSS) are widely deployed in generator excitation systems, playing a crucial role in suppressing low-frequency oscillations and improving power system stability. For example, in response to subsynchronous resonance phenomena, an "impedance reshaping" oscillation suppression strategy has been proposed for both the turbine and grid sides. On the wind turbine side, optimization, supplementation, or improvement of the converter control circuitry, including embedding digital blocking filters or adding additional damping control circuitry, enhances its damping characteristics for specific frequency dynamics. On the grid side, a set of customized voltage source converters capable of outputting subsynchronous current is connected in parallel at key substations, and their output is appropriately controlled to alter the overall dynamic characteristics of the grid at the corresponding subsynchronous frequency, thereby suppressing oscillations.

[0004] However, most of the methods for suppressing broadband oscillations in related technologies are designed for specific methods, specific modes and offline models, and involve limited control devices, have unclear frequency ranges, and have poor control effects. They cannot cope with the challenges of scene combination explosion, extremely high model dimensionality and large time-varying oscillation frequency in real systems, and urgently need to be solved. Summary of the Invention

[0005] This invention provides a power system stabilizer to solve the problems of limited bandwidth and poor adaptability of broadband oscillation suppression methods in related technologies, thereby improving broadband damping capability and universal access performance of converters.

[0006] To achieve the above objectives, a first aspect of the present invention provides a power system stabilizer, comprising: a wideband oscillation detection component, which is used to filter out wideband oscillation components that satisfy a preset frequency range from the grid signal; a wideband amplitude and phase adjustment component, which is used to perform amplitude and phase correction on the wideband oscillation components based on preset oscillation suppression conditions to obtain corrected wideband oscillation components; and an output adapter component, which is used to generate a control signal for a target converter based on the corrected wideband oscillation components, and to control the target converter based on the control signal.

[0007] Furthermore, in some embodiments, the broadband oscillation detection component is a multi-band filter, which consists of a band-stop filter unit and a band-pass filter unit. The band-stop filter unit includes multiple first filter sub-units connected in series, each first filter sub-unit including at least one first filter. The band-stop filter unit is used to filter out interference noise signals in the power grid signal to obtain a filtered power grid signal. The band-pass filter unit includes multiple second filter sub-units connected in parallel, each second filter unit including at least one second filter. The band-pass filter unit is used to extract a broadband oscillation component satisfying the preset frequency range from the filtered power grid signal. The first filter and the second filter are at least one or a combination of band-pass filters, band-stop filters, high-pass filters, and low-pass filters.

[0008] Further, in some embodiments, the wideband amplitude-phase adjustment component includes: a disturbance injection identification subunit and an amplitude-phase correction subunit, wherein the input terminal of the disturbance injection identification subunit is connected to the output terminal of the wideband oscillation detection component, and the output terminal of the disturbance injection identification subunit is connected to the input terminal of the amplitude-phase correction subunit, for identifying the open-loop amplitude-frequency characteristic and open-loop phase-frequency characteristic of the wideband oscillation component based on the preset oscillation suppression condition; the output terminal of the amplitude-phase correction subunit is connected to the input terminal of the output adapter component, for correcting the phase and amplitude of the wideband oscillation component according to the open-loop amplitude-frequency characteristic and the open-loop phase-frequency characteristic, to obtain the corrected wideband oscillation component.

[0009] Furthermore, in some embodiments, the output adapter component includes an adaptive gain unit and a signal conversion unit, wherein the adaptive gain unit is used to dynamically scale the corrected wideband oscillation component to obtain a dynamically scaled signal; and the signal conversion unit includes a function to format the dynamically scaled signal to obtain a control signal for the target converter.

[0010] Furthermore, in some embodiments, the adaptive gain unit includes a capacity sensing subunit and a dynamic scaling subunit, wherein the capacity sensing subunit is used to acquire the operating parameters of the target converter and calculate the capacity adaptation coefficient based on the operating parameters; the dynamic scaling subunit is used to calculate the flexible gain coefficient based on the capacity adaptation coefficient and scale the corrected broadband oscillation component based on the flexible gain coefficient to obtain the dynamic scaling signal.

[0011] Furthermore, in some embodiments, the signal conversion unit includes a coordinate transformation subunit, a numerical mapping subunit, and a signal conversion subunit. The coordinate transformation subunit is used to perform coordinate transformation on the dynamically scaled signal to obtain a coordinate-transformed signal. The numerical mapping subunit is used to match the numerical range of the coordinate-transformed signal to the input specifications of a preset target converter controller to obtain a numerically mapped signal. The signal conversion subunit is used to perform format conversion on the numerically mapped signal to obtain the control signal for the target converter.

[0012] Furthermore, in some embodiments, the power system stabilizer further includes: a target converter, the target converter including a converter controller and a converter circuit, wherein the input terminal of the converter controller is connected to the output terminal of the output adapter component, the converter controller is used to generate circuit drive commands based on the control signals of the target converter; the converter circuit is used to adjust the power delivered to the grid according to the circuit drive commands.

[0013] The power system stabilizer provided by the present invention includes a wideband oscillation detection component, a wideband amplitude and phase adjustment component, and an output adapter component. After the wideband oscillation detection component extracts the wideband oscillation component from the grid signal, the wideband amplitude and phase adjustment component performs signal amplitude and phase correction, and finally the output adapter component converts the corrected signal into control commands adapted to the converter, thereby realizing the regulation of the target converter. This solves the problems of limited bandwidth and poor adaptability of wideband oscillation suppression methods in related technologies, and improves the wideband damping capability and the universal access performance of the converter.

[0014] To achieve the above objectives, a second aspect of the present invention provides a design method for a power system stabilizer, including the power system stabilizer described in any of the preceding claims.

[0015] Further, in some embodiments, the design method of the power system stabilizer includes the following steps: in response to the design requirements of the power system stabilizer, constructing the band-stop filter unit, the band-pass filter unit, the disturbance injection identification subunit, the amplitude and phase correction subunit, the adaptive gain unit, and the signal conversion unit; constructing the wideband oscillation detection component based on the band-stop filter unit and the band-pass filter unit, constructing the wideband amplitude and phase adjustment component based on the disturbance injection identification subunit and the amplitude and phase correction subunit, and constructing the output adapter component based on the adaptive gain unit and the signal conversion unit; obtaining the power system stabilizer based on the wideband oscillation detection component, the amplitude and phase adjustment component, and the output adapter component.

[0016] Furthermore, in some embodiments, after obtaining the power system stabilizer based on the wideband oscillation detection component, the frequency amplitude phase adjustment component, and the output adapter component, the method further includes: obtaining the current operating condition of the power grid; determining the target layout of the power system stabilizer based on the current operating condition, and deploying the power system stabilizer according to the target layout.

[0017] Furthermore, in some embodiments, the target arrangement is any one of an embedded arrangement, an external arrangement, and a customized arrangement.

[0018] The power system stabilizer provided by the present invention includes a wideband oscillation detection component, a wideband amplitude and phase adjustment component, and an output adapter component. After the wideband oscillation detection component extracts the wideband oscillation component from the grid signal, the wideband amplitude and phase adjustment component performs signal amplitude and phase correction, and finally the output adapter component converts the corrected signal into control commands adapted to the converter, thereby realizing the regulation of the target converter. This solves the problems of limited bandwidth and poor adaptability of wideband oscillation suppression methods in related technologies, and improves the wideband damping capability and the universal access performance of the converter.

[0019] Therefore, the present invention has the following beneficial effects: (1) This invention is practical for suppressing wideband, multi-mode oscillations from several Hz to several kHz, and has the characteristics of being distributed and adaptive.

[0020] (2) The power system stabilizer parameters of the present invention do not need to be customized in advance, do not depend on the machine-grid model, can achieve self-tuning, and are plug-and-play.

[0021] (3) The present invention is widely distributed in the power system source-grid-load-storage. According to the bandwidth characteristics of the connected converter, the control bandwidth and control capacity of the attached power system stabilizer (New-type Power System Stabilizer, NPSS) can be set to achieve coordinated and optimized operation. Attached Figure Description

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 A block diagram of a power system stabilizer provided according to an embodiment of the present invention; Figure 2 A schematic diagram of a power system stabilizer structure according to a specific embodiment of the present invention; Figure 3 A schematic diagram of a novel power system structure according to a specific embodiment of the present invention; Figure 4 A flowchart illustrating a design method for a power system stabilizer according to an embodiment of the present invention. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] The power system stabilizer provided according to an embodiment of the present invention will now be described with reference to the accompanying drawings.

[0025] Figure 1 This is a block diagram of a power system stabilizer provided according to an embodiment of the present invention.

[0026] like Figure 1 As shown, the power system stabilizer 10 includes: a wideband oscillation detection component 100, which is used to filter out wideband oscillation components that meet a preset frequency range from the grid signal; a wideband amplitude and phase adjustment component 200, which is used to correct the amplitude and phase of the wideband oscillation components based on preset oscillation suppression conditions to obtain corrected wideband oscillation components; and an output adapter component 300, which is used to generate a control signal for the target converter based on the corrected wideband oscillation components and control the target converter based on the control signal.

[0027] Specifically, the wideband oscillation detection component 100 in this embodiment of the invention is a wideband oscillation detector, which can quickly (i.e., low delay, low phase shift) and accurately (i.e., high precision, high resolution) filter out the wideband oscillation components within the frequency range to be controlled from the output signal, while suppressing / reducing the power frequency or DC components that cause interference and other frequency band information that does not need to be concerned. This can be achieved using various digital or analog filtering methods. The wideband amplitude-phase adjustment component 200 is a wideband amplitude-phase regulator, which provides corresponding amplitude and phase correction for the wideband oscillation components to be suppressed, so as to ensure that the additional current of the final output can play a sufficient role in oscillation suppression. Since the amplification / delay effect of each control link on different frequency components is different and the frequency characteristics of the injection point impedance are different, it is necessary to specify the amplitude and phase correction values ​​of different frequency points within the wideband range in the design. The output adapter component 300 is an adaptive output adapter, which can convert the output of the wideband amplitude-phase regulator into (additional) control signals adapted to the target converter.

[0028] It should be noted that the wideband oscillation detector, wideband amplitude-phase modulator, and adaptive output adapter can be divided into multiple frequency bands according to actual needs and feasibility (e.g., Each component is implemented independently, with parallel outputs between frequency bands. The connection order can be interchanged, split, or combined under specific conditions without affecting the overall logic and control effect.

[0029] In some embodiments, Figure 2 This is a schematic diagram of a power system stabilizer structure according to a specific embodiment of the present invention, such as... Figure 2 As shown, the wideband oscillation detection component 100 is a multi-band filter, which consists of a band-stop filter unit 101 and a band-pass filter unit 102. The band-stop filter unit 101 includes multiple first filter sub-units connected in series, each of which includes at least one first filter. The band-stop filter unit 101 is used to filter out interference noise signals in the power grid signal to obtain the filtered power grid signal. The band-pass filter unit 102 includes multiple second filter sub-units connected in parallel, each of which includes at least one second filter. The band-pass filter unit 102 is used to extract a wideband oscillation component that meets a preset frequency range from the filtered power grid signal. The first filter and the second filter are at least one or a combination of band-pass filters, band-stop filters, high-pass filters, and low-pass filters.

[0030] As one possible way to achieve this, such as Figure 2 As shown, the input signal (vector) is ,when When it is a tuple, it can be combined or split into... Process them separately, assuming the frequency band to be picked out is... include Each frequency group There is a starting frequency and a stop frequency ,and , corresponding to a bandwidth, will Setting it to 0 indicates starting from frequency 0. Set as This indicates that the frequency stops at infinity. The frequency values ​​in the code increase sequentially to indicate that there is no overlap between the bandwidths and that there is a certain interval between them. The bandwidth pass / resistive gain is set to... ,in The value can be either 0 or 1, representing respectively This is set to either a stopband or a passband. The passband represents the range of frequency components that need to be detected or filtered out, while the stopband represents the range of frequency components that do not need to be detected or filtered out. Adjacent weighting coefficients cannot be repeated. This means that the entire frequency band is sequentially divided into frequencies that need to be filtered out (not of interest) and frequencies that need to be extracted (suppressed). Typically, the operating frequency... or DC component ( High frequencies that cannot be controlled (from a certain high frequency to infinity) need to be placed in the stopband to prevent DC bias, power frequency components, and high-frequency noise from affecting the control effect; weighting coefficients can be set. ,in This indicates whether the band is assigned to the passband or the stopband. The higher the weight, the higher the requirement for passing / suppressing that frequency band.

[0031] It should be noted that, in order to prevent large-amplitude power frequency signal interference, a higher weight can be assigned to the stopband near the power frequency, or the frequency characteristics of the stopband and passband can be adaptively adjusted according to the experimental results of the experimenters. No specific restrictions are imposed here.

[0032] Specifically, since the broadband oscillation detector is essentially a multi-band filter, its design can be flexibly modified according to actual needs, in addition to general settings. For example, the stopband can be adjusted. It can be replaced with a high-pass frequency, and the cutoff frequency can be set to... For example, stopband It can be replaced with a low-pass frequency, and the cutoff frequency can be set to... For example, low-frequency stopband and high-frequency stopband It can be replaced with a passband, with a frequency range of [missing information]. For example, bandpass can be obtained by combining low-pass / bandpass and bandpass / high-pass through an "intersection" (∩) / series operation, and stopband can be obtained by combining low-pass / bandpass and bandpass / high-pass through a "parallel" (∩) / series operation. The wideband oscillation detector is obtained through parallel / interconnected operations. Therefore, it can be flexibly constructed from various filters (including but not limited to bandpass, bandstop, low-pass, and high-pass filters) by cross (series) / parallel (interconnected) connections.

[0033] It should be noted that since all converters have a controllable bandwidth range, which can be obtained through identification methods, the passband is usually only set within the controllable frequency range. Otherwise, even if the relevant passband is set, the control effect will be affected due to insufficient converter bandwidth. In particular, for customized NPSS, if it is necessary to use it to suppress certain specific high-frequency or low-frequency oscillations, the converter needs to be designed appropriately to ensure good controllability in the required frequency band. The specific requirements are high tracking accuracy (gain close to 1 and high linearity) and fast tracking speed (small phase shift).

[0034] Furthermore, the broadband oscillation detector, as a multi-band filter, can be configured in various ways. For example, the direct zero-pole placement method can be used, which is suitable for stopband or passband situations with few bandwidths and fixed frequency points. For a single passband / stopband, for example... and The center frequency is set to Bandwidth set to ;when At this time, corresponding to the first stopband, it is essentially a high-pass filter, and the cutoff frequency can be set. ;when At this time, corresponding to the last stopband, it is essentially a low-pass filter, and the cutoff frequency can be set. This can be achieved using a second-order analog filter, and then utilizing... function to Digital filters are obtained by transforming functions (such as zero-holding, bilinear transform, etc.).

[0035] As one possible implementation, embodiments of the present invention can directly design corresponding digital filters, such as bandpass and bandstop filters (excluding the aforementioned). and The stopband (of which), its expression can be, but is not limited to, as: , in, The sampling frequency; ; .

[0036] High-pass and low-pass filters (such as those mentioned above) k =1 and m (for stopband or other flexible construction cases), its expression can be, but is not limited to, as: , in, The sampling frequency; ; ; ; The value can be between 0.85 and 0.995. The smaller the value, the gentler the transition band, but the faster the transient response (smaller overshoot). The larger the value, the steeper the transition band, but the slower the transient response. A typical compromise value is 0.95. This invention does not impose specific limitations.

[0037] Furthermore, in embodiments of the present invention, for broadband oscillation detectors with multiple stopbands (including high-pass, low-pass, and passbands derived from stopbands) and passbands, the stopband transfer functions can be connected in series and the passband transfer functions in parallel to obtain an overall multi-band filter. Its expression can be, but is not limited to, as follows: , As another possible implementation, embodiments of the present invention can also employ a Finite Impulse Response (FIR) filter as a broadband oscillation detector. That is, a general multi-band filter with alternating stopbands and passbands can be used. Various algorithms can be employed, such as the optimal equiripple method for design. Corresponding standard functions are provided in different language environments, such as the scipy.signal.remez function in Python and the firpm function in Matlab. By inputting the aforementioned frequency band information and sampling rate parameters, the filter parameters of the FIR can be obtained, and then implemented in the controller.

[0038] It should be noted that the wideband oscillation detector is implemented as a multi-band filter. The output corresponding to one input can be a total output signal or multiple output signals representing multiple different frequency bands, which serve as the input of the subsequent wideband amplitude-phase modulator. The methods for implementing the multi-band filter can be combined and applied. In practice, they can be flexibly used according to actual needs, and no specific restrictions are imposed here.

[0039] Furthermore, in some embodiments, the wideband amplitude and phase adjustment component 200 includes: a disturbance injection identification subunit 201 and an amplitude and phase correction subunit 202, wherein the input terminal of the disturbance injection identification subunit 201 is connected to the output terminal of the wideband oscillation detection component 100, and the output terminal of the disturbance injection identification subunit 201 is connected to the input terminal of the amplitude and phase correction subunit 202, for identifying the open-loop amplitude-frequency characteristics and open-loop phase-frequency characteristics of the wideband oscillation component based on a preset oscillation suppression condition; the output terminal of the amplitude and phase correction subunit 202 is connected to the input terminal of the output adapter component 300, for correcting the phase and amplitude of the wideband oscillation component according to the open-loop amplitude-frequency characteristics and open-loop phase-frequency characteristics, to obtain the corrected wideband oscillation component.

[0040] Specifically, the wideband amplitude-phase adjustment component 200 is a wideband amplitude-phase regulator. Its input is the oscillation dynamics of the frequency range of interest output by the wideband oscillation detector, and its output is the control reference signal for the subsequent stages of the drive controller and the converter. Its main function is to adjust the amplitude-frequency and phase-frequency relationship between the input and output, so that the voltage-current relationship of the controlled oscillation frequency at the injection point meets a specific relationship. This includes two stages: open-loop amplitude-phase relationship identification based on disturbance injection (i.e., disturbance injection identification sub-unit) and wideband amplitude-phase transfer function design (i.e., amplitude-phase correction sub-unit).

[0041] As one possible implementation, for the disturbance injection identification subunit 201, let the oscillation frequency range that the NPSS wants to suppress be... The signal injection perturbation method is used to test three sets of open-loop amplitude-frequency and phase-frequency characteristics, which are the union of the above multiple passbands. First, the open-loop (amplitude, phase) frequency response characteristics between the current from the additional control injection point to the grid connection point of the equipment (assuming that the current flowing to the equipment is positive, which does not affect the design principle) are tested. This includes the dynamic characteristics of the amplitude and phase regulation subsequent control links (including adaptive adapter and converter part control links), converter primary equipment, etc., at the frequency of interest; secondly, the frequency response characteristics between the injected current at the grid connection point of the equipment (note that the current flowing to the equipment is positive) and the voltage at the grid connection point. This reflects the power grid's response characteristics to the frequency of interest; secondly, it reflects the frequency response characteristics from the grid connection point voltage of the equipment to the output of the broadband oscillation detector. This includes the dynamic characteristics of the feedback measurement stage and the wideband oscillation detector at the frequency of interest; finally, it includes the frequency response characteristics from the additional control injection point to the output of the wideband oscillation detector. This represents the overall effect of the three frequency response characteristics mentioned above.

[0042] Furthermore, the perturbation identification method can be implemented in various ways. For example, it can employ a single-frequency or multi-frequency sinusoidal sweep method with a fixed frequency sequence. That is, within a given frequency range, one or more sinusoidal signals of different frequencies are injected (synthesized) each time. The frequency (group) sequence is given in advance, and the amplitude and phase sequences under this discrete frequency (group) sequence are obtained. to Group 4 The set of frequencies (groups) can cover the entire given frequency range, and the minimum resolution is not lower than a certain threshold value (e.g., ...). For example, a single-frequency or multi-frequency sinusoidal sweep method using adaptive frequency sequences can be employed. Since the frequency characteristics of an open-loop system change at different frequency points with varying steepness, a fixed frequency sequence may have some frequency bands with excessively small intervals, reducing efficiency, while others may have excessively large intervals, reducing accuracy. Therefore, an adaptive adjustment of the frequency interval based on the gradient of the output amplitude and phase frequency changes can be adopted. Initial frequency intervals and amplitude and phase frequency change limits are set. When the amplitude and phase frequency changes of adjacent frequency points are detected to be higher than the limits, a new frequency point is interpolated for injection testing according to a certain rule (e.g., bisection method). Conversely, when the amplitude and phase frequency changes of adjacent frequency points are lower than a certain percentage of the limits (e.g., 50%), the frequency interval is increased according to a certain rule (e.g., extrapolated to 90%) to ensure smooth amplitude and phase frequency changes and improve identification accuracy. The open-loop frequency characteristics on the adaptive frequency sequence can also be denoted as… A set of frequencies that can cover the entire given frequency range; or, for example, an improved broadband signal method can be used. The classic broadband signal method injects an excitation covering a wide frequency range at once, typically a pseudo-random binary sequence or a linear / logarithmic frequency-modulated pulse, and then obtains the transfer function of the open-loop system through signal processing / identification algorithms. Or continuous frequency amplitude-frequency and phase-frequency response functions , Therefore, it is necessary to limit the frequency range to the aforementioned frequency band of interest. For example, this can be achieved by setting the parameters of the excitation signal or by performing filtering operations on the wideband signal as described in the detection method above, and then adjusting the continuous frequency amplitude-frequency and phase-frequency response functions. , Sampling of fixed or adaptive frequency sequences yields... This set enables open-loop amplitude-phase correlation identification based on perturbation injection.

[0043] As one possible implementation method, for the amplitude-phase correction subunit 202, the embodiments of the present invention can employ impedance shaping, the design goal of which is to transform the impedance of the controlled device at different frequency points in the frequency band of interest to a set value, that is, the impedance of the amplitude-phase modulator at the frequency point The amplitude and phase can be, but are not limited to, expressed as: , , in, For the set impedance value, and These are their absolute value and phase angle, respectively. Set to the characteristics of pure resistance or resistance plus reactance. These are weights for different frequencies (oscillation modes). When control capacity is limited, they are used to adjust (or allocate) the corresponding control intensity (capacity) based on the attention or importance of the oscillation mode.

[0044] As one possible implementation method, for the amplitude and phase correction subunit 202, this embodiment of the invention can also employ a closed-loop frequency response shaping method. Its design goal is to ensure that the closed-loop system is stable and has sufficient amplitude and phase margins. Since the above-mentioned disturbance identification method can obtain the open-loop system... or Frequency response characteristics at discrete frequency points (i.e.) or Therefore, embodiments of the present invention can employ two types of methods to design the closed-loop control strategy of the system. For example, the frequency response characteristics of the open-loop system can first be transformed into a transfer function using fitting or other identification algorithms, and then classical methods (such as the zero-pole placement method) can be used to obtain the controller transfer function that stabilizes the system. Alternatively, the Bode plot of the open-loop system can be obtained directly based on the discrete frequency response characteristics, and then classical frequency domain design methods, such as the Bode plot shaping method, can be used to design the feedback control transfer function to ensure that the closed-loop system is not only stable but also has sufficient engineering margin. For multimodal oscillations, a "frequency band-based" or "mode-based" design strategy can be adopted, and different weights can be configured for different frequency bands or modes. (Corresponding to control capacity allocation).

[0045] Furthermore, in some embodiments, the output adapter component 300 includes an adaptive gain unit 301 and a signal conversion unit 302, wherein the adaptive gain unit 301 is used to dynamically scale the corrected wideband oscillation component to obtain a dynamically scaled signal; the signal conversion unit 302 includes a function to format the dynamically scaled signal to obtain a control signal for the target converter.

[0046] Specifically, the output adapter component includes multiple adaptation stages. These stages include considering the differences between the NPSS input and output signals to achieve signal conversion and matching. For example, stationary coordinates and The synchronous rotation coordinate transformation and adaptation process also includes considering the differences in control capacity requirements at different frequency ranges that may result from changes in system operating conditions. By fine-tuning the gain between different frequencies, the control power can be optimized. The adaptation process may also include considering the uncertainty of system disturbances and the limitations of overall control capacity, and adaptively adjusting the overall gain of the controller to avoid output distortion that could affect other functions of the converter or degrade the control effect.

[0047] Furthermore, in some embodiments, the adaptive gain unit 301 includes a capacity sensing subunit 3011 and a dynamic scaling subunit 3012, wherein the capacity sensing subunit 3011 is used to acquire the operating parameters of the target converter and calculate the capacity adaptation coefficient based on the operating parameters; the dynamic scaling subunit 3012 is used to calculate the flexible gain coefficient based on the capacity adaptation coefficient and scale the corrected broadband oscillation component based on the flexible gain coefficient to obtain the dynamic scaling signal.

[0048] It should be noted that since the capacity used for oscillation suppression is limited, and considering the variable operating conditions and uncertainty of disturbances in the system, the control output may not match the available control capacity. If it is too small, the control effect will be weak, and if it is too large, it may cause adverse effects such as saturation, overshoot, and distortion. Therefore, an additional overall adaptive gain needs to be set to solve this problem and achieve the best fit.

[0049] As one possible implementation, the adaptive gain unit 301 is mainly used for capacity sensing and dynamic scaling flexible gain control. It first senses in real time information such as the design limitations, operating constraints, and current operating conditions of the attached converter, and then calculates the available capacity or receives the capacity allocated to the oscillation suppression function. This is typically the available complex power, peak current, etc. Taking the latter as an example, let the available peak current value be... Based on the output of the amplitude-phase regulator and the previously identified The calculated peak current value is The available / expected ratio (i.e., "fitness") is calculated, and its expression can be, but is not limited to, as follows: , in, It is a small adjustment amount (e.g.) (This is to prevent division by zero.)

[0050] Next, a preliminary adaptive gain is designed. for of The type function or its approximation can have hysteresis characteristics, that is, the expression for adaptive gain can be, but is not limited to, expressed as:

[0051] in, For the sigmoid function or its approximation, to save computational resources, a piecewise continuous proportional function that is computationally simple and has excellent performance is recommended as the sigmoid function approximation. That is, the expression for the adaptive gain can be, but is not limited to, expressed as: , in, , These are the maximum and minimum gains, respectively; The values ​​>1 and <1 respectively represent the corresponding turning points; As a proportional coefficient, this function ensures that when the capacity is sufficient, a larger but not excessive overall gain is used to fully utilize the control capacity and obtain a better control effect; while when the expected value exceeds the available control capacity, it is smoothly compressed proportionally, while retaining a small gain or output capability to prevent oscillation suppression from completely failing.

[0052] Finally, a post-processing dynamic smoothing and anti-jitter stage is set up, based on the preliminary adaptive gain calculated above. The signal may jitter drastically due to measurement noise, necessitating dynamic smoothing and jitter reduction design. A typical example is using a first-order low-pass filter, whose expression can be, but is not limited to, as follows: , in, Typically, a value of 0.05 to 0.2 is used to obtain an adaptive gain. Changes have inertia, avoiding abrupt changes, thereby achieving capacity sensing and dynamic scaling flexible gain control.

[0053] Furthermore, in some embodiments, the signal conversion unit 302 includes a coordinate transformation subunit 3021, a numerical mapping subunit 3022, and a signal conversion subunit 3023. The coordinate transformation subunit 3021 is used to perform coordinate transformation on the dynamically scaled signal to obtain a coordinate-transformed signal; the numerical mapping subunit 3022 is used to match the numerical range of the coordinate-transformed signal to the input specification of the preset target converter controller to obtain a numerically mapped signal; and the signal conversion subunit 3023 is used to perform format conversion on the numerically mapped signal to obtain the control signal of the target converter.

[0054] Specifically, the signal conversion unit in this embodiment of the invention provides signal conversion (such as digital-to-analog conversion, photoelectric conversion, level conversion) and / or numerical mapping (such as mapping from secondary-side numerical values ​​to primary-side numerical values) and / or coordinate transformation (such as...) between the amplitude-phase regulator output and the converter control interface or a custom converter. , arrive Coordinate transformation), the coordinate transformation subunit realizes two-phase rotation. Coordinate system, two-phase stationary Coordinate system and three-phase stationary The bidirectional coordinate conversion between coordinate systems matches the coordinate architecture of the original control system of the converter; the numerical mapping subunit completes the range scaling and mapping conversion of control values ​​between the per-unit values ​​of the relay protection secondary system and the actual physical quantities of the converter primary system, unifying the signal value range; the signal conversion subunit realizes digital-to-analog conversion, opto-isolation conversion, and control level matching conversion, and finally generates a standardized interface signal to be sent to the converter controller, thereby solving the problem of incompatible control signals caused by the inconsistency of control interface protocols and electrical specifications of different converter models.

[0055] Furthermore, in some embodiments, the power system stabilizer further includes: a target converter 400, which includes a converter controller 401 and a converter circuit 402, wherein the input terminal of the converter controller 401 is connected to the output terminal of the output adapter component 300, and the converter controller 401 is used to generate circuit drive commands based on the control signals of the target converter 400; the converter circuit 402 is used to adjust the power delivered to the grid according to the circuit drive commands.

[0056] Specifically, the interface control signal generated by the output adapter component 100 is connected to the control input port of the converter controller 401. After receiving the additional control signal, the converter controller generates power device drive pulses by superimposing its original closed-loop control logic. The converter control circuit consists of a main power loop composed of power switching devices, and collects the three-phase input current in real time. Under the control of the drive pulse, the active and reactive power are rapidly processed. By injecting damping power into the grid, the original wideband oscillation component of the grid is offset, thus completing the oscillation suppression. At the same time, the converter controller feeds back the converter operating condition parameters to the capacity sensing subunit in the output adapter component in real time.

[0057] It should be noted that the power system stabilizer of this invention can be applied to diverse source-grid-load-storage equipment such as wind power / photovoltaic and other new energy units, energy storage equipment, STATCOM (or SVG) reactive power compensation equipment, flexible transmission converters, and power electronic interface loads. The power system stabilizer of this invention can rely on an existing external target converter to achieve power regulation, or it can be equipped with a dedicated converter controller and converter control circuit, and has its own independent converter. That is to say, it can operate by relying on other converters, or it can be independently put into operation with its own converter. No specific restrictions are made here.

[0058] The power system stabilizer proposed in this invention will be described below with reference to a specific embodiment.

[0059] Specifically, Figure 3 A schematic diagram of a novel power system structure according to a specific embodiment of the present invention.

[0060] like Figure 3As shown, NPSS can be used with new energy units such as wind power / photovoltaics, energy storage devices, STATCOM (Static Synchronous Compensator), and Static Var Generator (Static Var Generator). A variety of source-grid-load-storage devices, such as generators (SVG) reactive power compensation devices, flexible transmission converters, and power electronic interface loads, are used in combination and distributed over a wide area. Each device operates independently and can be designed in a coordinated manner. They can be embedded as a functional module into the converter control system, referred to as an embedded NPSS; or they can be used as a relatively independent secondary control device, directly detecting grid electrical signals or receiving input signals from the converter, and generating outputs after processing by their own control algorithms, which are then injected as additional control signals into specific signal points within the converter, forming an external NPSS; or they can be used as a relatively independent primary and secondary combined control device, which independently detects, calculates, and generates control signals to drive a customized power electronic converter to exchange power with the grid and achieve oscillation suppression function, referred to as a customized NPSS. Among these, embedded NPSS and external NPSS rely on the primary power equipment of other converters to achieve energy exchange with the grid, so their control capacity is limited by the controllable capacity allocated to the oscillation suppression function by the latter. Customized NPSS has an independent converter, and its capacity can be flexibly set according to actual needs, but because it requires additional power circuitry, its cost is higher.

[0061] It should be noted that a customized NPSS can be regarded as a specially designed wideband converter with embedded or external NPSS reconfiguration. Therefore, a customized NPSS can also be decomposed into a customized NPSS controller and a customized NPSS converter.

[0062] Furthermore, the NPSS core control algorithm can be based on stationary coordinates or Synchronous rotation coordinate construction, The input corresponding to the stationary coordinate system is the three-phase voltage of the bus at the observation point or a certain equivalent three-phase voltage constructed from a specific current and impedance. It is the instantaneous value in the stationary coordinate system, denoted as... ; The input corresponding to the synchronous rotating coordinate system is the bus voltage at the observation point or a certain equivalent voltage constructed from a specific current and impedance, obtained through Park transformation. These are the direct and quadrature axes in the synchronous rotating coordinate system. ) component, denoted as The output of the NPSS varies slightly depending on the implementation method. These differences may include, but are not limited to, the additional control current reference value in the stationary coordinate system. Or add a control voltage reference value This implementation method is applicable to embedded NPSS, external NPSS, or custom NPSS controllers built with stationary coordinates or synchronous rotating coordinates; it also includes... Additional control current reference value for synchronous rotating coordinate system Or add a control voltage reference value This implementation is applicable to embedded NPSS, external NPSS, or custom NPSS controllers built with stationary or synchronously rotating coordinates; it also includes differences in intermediate variables, such as additional three-phase modulation ratios. Additional (instantaneous) active power reference value and reactive power reference value Additional frequency deviation (or ) and voltage amplitude deviation Furthermore, for embedded and external NPSS, the additional control output is summed with the corresponding variables in the converter's internal control strategy, and then processed before being applied to the converter to drive it to generate the corresponding additional current. For custom NPSS, the output is processed using appropriate digital algorithms and then directly drives the custom NPSS converter to generate a three-phase current that suppresses oscillations, which is injected into the converter's connection bus. It indicates addition or increment.

[0063] The power system stabilizer provided by the present invention includes a wideband oscillation detection component, a wideband amplitude and phase adjustment component, and an output adapter component. After the wideband oscillation detection component extracts the wideband oscillation component from the grid signal, the wideband amplitude and phase adjustment component performs signal amplitude and phase correction, and finally the output adapter component converts the corrected signal into control commands adapted to the converter, thereby realizing the regulation of the target converter. This solves the problems of limited bandwidth and poor adaptability of wideband oscillation suppression methods in related technologies, and improves the wideband damping capability and the universal access performance of the converter.

[0064] This invention also provides a design method for a power system stabilizer, including the power system stabilizer described above.

[0065] Figure 4 A flowchart illustrating a design method for a power system stabilizer according to an embodiment of the present invention.

[0066] like Figure 4 The design method of the power system stabilizer includes the following steps: In step S401, in response to the design requirements of the power system stabilizer, a band-stop filter unit, a band-pass filter unit, a disturbance injection identification subunit, an amplitude and phase correction subunit, an adaptive gain unit, and a signal conversion unit are constructed.

[0067] In step S402, a wideband oscillation detection component is constructed based on the band-stop filter unit and the band-pass filter unit, a wideband amplitude and phase adjustment component is constructed based on the disturbance injection identification subunit and the amplitude and phase correction subunit, and an output adaptation component is constructed based on the adaptive gain unit and the signal conversion unit.

[0068] In step S403, a power system stabilizer is obtained based on the wideband oscillation detection component, the frequency amplitude phase adjustment component, and the output adapter component.

[0069] Furthermore, in some embodiments, after obtaining the power system stabilizer based on the broadband oscillation detection component, the frequency amplitude phase adjustment component, and the output adapter component, the method further includes: obtaining the current operating conditions of the power grid; determining the target layout of the power system stabilizer based on the current operating conditions; and deploying the power system stabilizer according to the target layout.

[0070] Furthermore, in some embodiments, the target arrangement is any one of an embedded arrangement, an external arrangement, and a customized arrangement.

[0071] The power system stabilizer provided by the present invention includes a wideband oscillation detection component, a wideband amplitude and phase adjustment component, and an output adapter component. After the wideband oscillation detection component extracts the wideband oscillation component from the grid signal, the wideband amplitude and phase adjustment component performs signal amplitude and phase correction, and finally the output adapter component converts the corrected signal into control commands adapted to the converter, thereby realizing the regulation of the target converter. This solves the problems of limited bandwidth and poor adaptability of wideband oscillation suppression methods in related technologies, and improves the wideband damping capability and the universal access performance of the converter.

[0072] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0073] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0074] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A power system stabilizer, characterized in that, include: A wideband oscillation detection component is used to filter out wideband oscillation components that meet a preset frequency range from the power grid signal. A wideband amplitude and phase adjustment component is used to correct the amplitude and phase of the wideband oscillation component under a preset oscillation suppression condition to obtain the corrected wideband oscillation component. An output adapter component is provided, which is used to generate a control signal for the target converter based on the corrected wideband oscillation component, and to control the target converter based on the control signal.

2. The power system stabilizer according to claim 1, characterized in that, The wideband oscillation detection component is a multi-band filter, which consists of a band-stop filter unit and a band-pass filter unit. The band-stop filter unit includes multiple first filter sub-units connected in series. Each first filter sub-unit includes at least one first filter. The band-stop filter unit is used to filter out interference noise signals in the power grid signal to obtain a filtered power grid signal. The bandpass filter unit includes multiple parallel second filter sub-units, each second filter unit includes at least one second filter, and the bandpass filter unit is used to extract a wideband oscillation component that satisfies the preset frequency range from the filtered power grid signal; The first filter and the second filter are at least one or a combination of bandpass filter, bandstop filter, high-pass filter and low-pass filter.

3. The power system stabilizer according to claim 1, characterized in that, The broadband amplitude and phase adjustment component includes: a disturbance injection identification subunit and an amplitude and phase correction subunit, wherein... The input terminal of the disturbance injection identification subunit is connected to the output terminal of the broadband oscillation detection component, and the output terminal of the disturbance injection identification subunit is connected to the input terminal of the amplitude and phase correction subunit. It is used to identify the open-loop amplitude frequency characteristics and open-loop phase frequency characteristics of the broadband oscillation component based on the preset oscillation suppression condition. The output terminal of the amplitude and phase correction subunit is connected to the input terminal of the output adapter component, and is used to correct the phase and amplitude of the broadband oscillation component according to the open-loop amplitude-frequency characteristic and the open-loop phase-frequency characteristic, so as to obtain the corrected broadband oscillation component.

4. The power system stabilizer according to claim 1, characterized in that, The output adapter component includes: an adaptive gain unit and a signal conversion unit, wherein... The adaptive gain unit is used to dynamically scale the corrected wideband oscillation component to obtain a dynamically scaled signal. The signal conversion unit includes a function for formatting the dynamic scaling signal to obtain a control signal for the target converter.

5. The power system stabilizer according to claim 4, characterized in that, The adaptive gain unit includes: a capacity-aware subunit and a dynamic scaling subunit, wherein... The capacity sensing subunit is used to acquire the operating parameters of the target converter and calculate the capacity adaptation coefficient based on the operating parameters. The dynamic scaling subunit is used to calculate the flexible gain coefficient based on the capacity adaptation coefficient, and to scale the corrected broadband oscillation component based on the flexible gain coefficient to obtain the dynamic scaling signal.

6. The power system stabilizer according to claim 5, characterized in that, The signal conversion unit includes a coordinate transformation subunit, a numerical mapping subunit, and a signal conversion subunit, wherein... The coordinate transformation subunit is used to perform coordinate transformation on the dynamic scaling signal to obtain the coordinate transformed signal; The numerical mapping subunit is used to match the range of the coordinate-transformed signal value to the input specification of the preset target converter controller to obtain the numerically mapped signal. The signal conversion subunit is used to convert the format of the numerically mapped signal to obtain the control signal of the target converter.

7. The power system stabilizer according to claim 1, characterized in that, Also includes: The target converter includes a converter controller and a converter circuit, wherein, The input terminal of the converter controller is connected to the output terminal of the output adapter component, and the converter controller is used to generate circuit drive commands based on the control signal of the target converter; The converter circuit is used to adjust the power supplied to the power grid according to the circuit drive command.

8. A design method for a power system stabilizer as described in any one of claims 1-7, characterized in that, Includes the following steps: In response to the design requirements of power system stabilizers, the following components are constructed: a band-stop filter unit, a band-pass filter unit, a disturbance injection identification subunit, an amplitude and phase correction subunit, an adaptive gain unit, and a signal conversion unit. The wideband oscillation detection component is constructed based on the band-stop filter unit and the band-pass filter unit, the wideband amplitude and phase adjustment component is constructed based on the disturbance injection identification subunit and the amplitude and phase correction subunit, and the output adaptation component is constructed based on the adaptive gain unit and the signal conversion unit. A power system stabilizer is obtained based on the wideband oscillation detection component, the frequency amplitude phase adjustment component, and the output adapter component.

9. The method according to claim 8, characterized in that, After obtaining the power system stabilizer based on the broadband oscillation detection component, the frequency amplitude phase adjustment component, and the output adapter component, the system further includes: Obtain the current operating status of the power grid; Based on the current operating conditions, the target layout of the power system stabilizer is determined, and the power system stabilizer is deployed according to the target layout.

10. The method according to claim 9, characterized in that, The target layout method can be any one of the following: embedded layout, external layout, and customized layout.

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