A method and equipment for rapidly and effectively suppressing broadband oscillations in new energy power systems

Abstract

This invention relates to the field of power system stability control and power electronics grid connection technology, and discloses a method and equipment for rapidly and effectively suppressing broadband oscillations in new energy power systems. Addressing the problem of broadband oscillations in new power systems containing a high proportion of new energy and power electronic equipment, this invention first collects the system operating status, identifies the current oscillation mode and other information based on a system identification method, and then adaptively tunes the parameters of the installed filter device. This allows the filter device to provide additional compensation power beyond the fundamental power, thereby rapidly and effectively suppressing complex broadband oscillations occurring in the system. The filter device is mainly installed at energy storage power stations, large-capacity new energy generator sets, or key hub nodes of the power system, thereby improving the safety and stability of the new energy power system.

Description

Technical Field

[0001] This invention belongs to the technical field of power system stability control and power electronics grid connection, and more specifically, relates to a method and equipment for rapidly and effectively suppressing broadband oscillations in new energy power systems. Background Technology

[0002] With the high proportion of power electronic equipment such as wind power, photovoltaics, energy storage, and flexible DC transmission being integrated, the power grid exhibits characteristics of low inertia, weak impedance, and strong control coupling. Grid-connected converters for new energy power generation equipment often employ a multi-loop control structure consisting of an inner current loop and outer loops (DC voltage loop, power loop, voltage / reactive power loop, speed loop, etc.). In power systems with a high proportion of power electronic grid connection, suppressing low-damped oscillations and improving system stability have long been issues of concern in engineering and research fields. Currently, common methods in the field mainly rely on controller parameter tuning, or introducing filtering devices and additional damping within the control loop to improve dynamic characteristics. For example: Chinese patent "CN114006386B A control method and system for suppressing grid-connected wideband oscillations of a full-power converter" monitors the three-phase current on the AC side of the main controller of the full-power converter online, extracts the frequency of the current maximum oscillation component in real time, and automatically identifies the current oscillation frequency when oscillations of any frequency occur. Then, through dynamic bandpass filtering, additional damping is precisely added at the current oscillation frequency to suppress the oscillation. Although this technical solution introduces a bandpass filter to achieve wideband oscillation suppression, it superimposes the obtained additional modulation voltage signal onto the pulse width modulator. That is, this technical solution essentially achieves the wideband oscillation suppression effect by regulating the control loop. Chinese patent "CN116960990B Method, Apparatus, System and Storage Medium for Suppressing Wideband Oscillations in Power Systems" adjusts the component parameters (such as transfer function) of the target oscillation suppression element (such as active damper) in real time based on the oscillation frequency and oscillation amplitude, so that the target oscillation suppression element can adaptively suppress wideband oscillations, thereby achieving a good suppression effect even when there are uncertainties in the system parameters. However, this technical solution also loads the oscillation suppression element into the power electronic converter. That is, this technical solution essentially achieves the wideband oscillation suppression effect by regulating the control loop.

[0003] Although broadband oscillations can be suppressed by tuning or regulating the controller or control loop, tuning or regulating the controller or control loop often requires consideration of many influencing factors, and may also require the establishment of a mathematical model of the grid-connected device and the power grid. The regulation method is relatively complex, and it is often impossible to modify the already packaged controller or control loop.

[0004] Therefore, how to achieve broadband oscillation suppression in power systems in a simpler way without interfering with the controller or control loop is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] In view of the above-mentioned defects or improvement needs of the existing technology, the present invention provides a method and equipment for quickly and effectively suppressing broadband oscillations in new energy power systems. Its purpose is to achieve broadband oscillation suppression of power systems in a simpler way without interfering with the controller or control loop.

[0006] To achieve the above objectives, the present invention is proposed.

[0007] According to a first aspect of the present invention, a method for rapidly and effectively suppressing broadband oscillations in a new energy power system is provided, comprising: The oscillation response signal of the power system under small-signal disturbance is acquired. Based on the oscillation response signal, the system is identified, the oscillation mode of the power system is determined, and its oscillation mode parameters are acquired. The oscillation mode parameters include the oscillation frequency and the damping ratio. Based on the parameters of the adaptive tuning filter device for the oscillation mode parameters, the filter device includes a tunable filter structure and a damping structure. The parameter tuning objective is that when the filter device is connected to the power system, it can select the oscillation mode to be suppressed and provide additional compensation power in addition to the fundamental power, thereby enhancing the damping ratio of the power system to the oscillation mode without affecting the fundamental power of the power system. The filter device, after parameter tuning, is connected to the power system to filter out oscillation components other than the fundamental frequency, thereby achieving broadband oscillation suppression.

[0008] According to a second aspect of the present invention, a device for rapidly and effectively suppressing broadband oscillations in a new energy power system is provided, comprising a filtering device and a control device. The filtering device includes a tunable filtering structure and a damping structure, and the control device has an acquisition module, an identification module, a parameter tuning module, and an access module. The acquisition module is used to acquire the oscillation response signal of the power system under small signal disturbance. The identification module is used to identify the system based on the oscillation response signal, determine the oscillation mode of the power system and obtain its oscillation mode parameters, including the oscillation frequency and damping ratio; The parameter tuning module is used to adaptively tune the parameters of the filter device based on the oscillation mode parameters. The filter device includes a tunable filter structure and a damping structure. The parameter tuning objective is that when the filter device is connected to the power system, it can select the oscillation mode to be suppressed and provide additional compensation power in addition to the fundamental power, thereby enhancing its damping ratio without affecting the fundamental power of the power system. The access module is used to connect the filter device with completed parameter tuning to the power system to filter out oscillation components other than the fundamental frequency, thereby achieving broadband oscillation suppression.

[0009] In summary, compared with the prior art, the technical solutions conceived in this invention have the following main advantages: This invention identifies the oscillation modes of a power system, tunes the parameters of a filter device accordingly based on the oscillation mode parameters, and directly connects the configured filter device to locations in the power system with a risk of broadband oscillations. After the filter device is connected, it can select the oscillation mode to be suppressed after oscillations occur, enhance its damping ratio, and not affect the fundamental frequency of the power system, thus quickly suppressing the oscillations. Compared to suppressing broadband oscillations by adjusting controllers or control loops, this invention's solution does not require intervention in controllers or control loops, does not rely on complex mechanism models, improves the small-signal stability of renewable energy grid-connected systems, and does not require temporary complex control adjustments after disturbances occur, thereby improving the timeliness and engineering practicality of oscillation suppression. In other words, this invention breaks with conventional thinking on broadband oscillation suppression, proposing a completely new approach. Without changing the original control structure of the power system, broadband oscillation suppression can be achieved simply by identifying and tuning the parameters of the filter device and deploying the configured filter device at key locations. Experiments have verified that this solution achieves good suppression of broadband oscillations. Attached Figure Description

[0010] Figure 1 This is a flowchart of the steps of a broadband oscillation suppression method in a new energy power system according to an embodiment of the present invention.

[0011] Figure 2 This is a system topology of a dual-fan grid-connected four-fan two-zone system in one embodiment.

[0012] Figure 3 This is a schematic diagram of the structure of a filtering device in one embodiment of the present invention.

[0013] Figure 4 In Example 1, under the disturbance scenario of a step change in the reactive power reference value of wind turbine WT1, the power and frequency signal waveforms of the wind power collection system without a filter and with the filter installed are used to suppress system oscillation. Among them, (a) is a waveform comparison of the active power of the grid without a filter and with a filter installed, (b) is a waveform comparison of the reactive power of the grid without a filter and with a filter installed, and (c) is a waveform comparison of the phase-locked loop frequency of wind turbine WT1 without a filter and with a filter installed.

[0014] Figure 5In Example 2, under the disturbance scenario of a phase step in the phase-locked loop of wind turbine WT1, the power and frequency signal waveforms of the wind power collection system without a filter and with the filter installed are used to suppress system oscillation. Among them, (a) is a waveform comparison of the active power of the power grid without a filter and with a filter installed, (b) is a waveform comparison of the reactive power of the power grid without a filter and with a filter installed, (c1) is a waveform of the phase-locked loop frequency of wind turbine WT1 without a filter, and (c2) is a waveform of the phase-locked loop frequency of wind turbine WT1 with a filter installed. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0016] In a first aspect, the present invention claims a method for rapidly and effectively suppressing broadband oscillations in a new energy power system.

[0017] like Figure 1 The diagram shown is a flowchart of the steps in a broadband oscillation suppression method for a new energy power system according to an embodiment of the present invention. The following is a summary of the steps. Figure 1 The method is described in detail.

[0018] S111. For areas prone to broadband oscillations in new energy power systems, filter devices shall be installed in application scenarios (energy storage power stations, large-capacity new energy generator sets, or key hub nodes of the system).

[0019] like Figure 2 The diagram shows the system topology of a four-unit, two-zone system with two wind turbines connected to the grid, where B1 is the receiving end, B2 is the sending end, and C is the wind turbine grid connection node. This invention involves installing filtering devices at critical locations in the power system. Generally, filtering devices are considered for locations prone to broadband oscillations, such as one or more locations within large-capacity new energy generator sets, energy storage power stations, or critical hub nodes in the power system with broadband oscillation risks.

[0020] S112. Collect system operating status (such as output power and frequency), and use system identification methods to identify the current oscillation mode and other information.

[0021] In other words, this step involves: acquiring the oscillation response signal of the power system under small-signal disturbance, identifying the system based on the oscillation response signal, determining the oscillation mode of the power system, and acquiring its oscillation mode parameters, including the oscillation frequency and damping ratio.

[0022] In one embodiment, the oscillation response signal of a real power system under small-signal disturbance can be acquired, or a system topology model can be established to simulate the oscillation state of the power system under disturbance. After the power system oscillates under small-signal disturbance, the oscillation response signal of the system is acquired, and the oscillation mode parameters of the power system are identified using a system identification method.

[0023] In one embodiment, the method of applying a small-signal disturbance to the power system is to cause a step change in the reactive power parameter value of the wind turbine at a set time point, or to apply a phase disturbance to the phase-locked loop (PLL) of the power system at a set time point.

[0024] Specifically, the location of the oscillation response signal is obtained, including the location of the power system to be connected to the filter device, and the sending or receiving end of the power system. This oscillation response signal contains key information such as the active power, reactive power, and frequency of the power system after oscillation occurs.

[0025] In one embodiment, after acquiring the oscillation response signal, in order to improve the reliability of identification, the acquired signal can be synchronized, mean removed, sampled at a lower rate, and subjected to sliding window truncation.

[0026] The system identification method can adopt existing methods, such as Prony identification method, MatrixPencil identification method or ERA identification method.

[0027] Taking the Matrix Pencil identification method as an example, the oscillating response signal of the system is collected to form a discrete observation sequence. The Matrix Pencil method can model the system response as a linear superposition of complex exponential signals, as shown below: ; in, Let i be the k-th observation in the observation sequence, and i be the index of the oscillation mode. Let be the complex amplitude of the i-th oscillation mode. The z-domain eigenvalues ​​of the i-th oscillation mode can be obtained based on the observation sequence by constructing Hankel matrix pairs, SVD order reduction, and generalized eigenvalues. Then, based on the solution... Extract the attenuation factor of the i-th oscillation mode. and angular frequency The three satisfy the following relationship: ; Let be the eigenvalue of the i-th oscillation mode, which includes the attenuation factor of the i-th oscillation mode. and angular frequency ; Therefore, the attenuation factor is extracted. and angular frequency The formula is: ; ; In the formula, This represents the observation time interval of the observation sequence.

[0028] Identify the attenuation factor of the i-th oscillation mode and angular frequency Then, the frequency of the i-th oscillation mode can be further determined. Damping ratio : ; ; The frequencies of all oscillation modes identified by the above system identification method are the oscillation frequencies.

[0029] S113. Based on oscillation mode, adaptively tune the filter device parameters.

[0030] This step actually involves: adaptively tuning the parameters of the filter device based on the oscillation mode parameters. The filter device includes a tunable filter structure and a damping structure. The parameter tuning objective is: when the filter device is connected to the power system, it can select the oscillation mode to be suppressed and provide additional compensation power beyond the fundamental power, thereby enhancing the damping ratio of the power system to the oscillation mode without affecting the fundamental power of the power system.

[0031] Specifically, after identifying the oscillation mode of the system through system identification, the parameters of the filter device can be tuned to suppress multimode oscillations and reduce the impact on the normal power frequency operation of the system.

[0032] In one embodiment, after identifying the oscillation modes of the power system through system identification, oscillation modes to be suppressed are selected from those with a damping ratio less than or equal to zero. The parameters of the filter device are then tuned based on the selected oscillation modes to be suppressed. Considering that the damping ratio reflects the rate of amplitude decay during system vibration, if the damping ratio of an oscillation mode is greater than 0, it indicates that the oscillation mode can decay to an equilibrium state relatively quickly, and therefore no additional means are needed to suppress it. However, for oscillation modes with a damping ratio close to or less than zero, it is difficult for them to decay to an equilibrium state quickly and spontaneously, and therefore they need to be the focus of suppression. This invention uses the damping ratio to screen out the oscillation modes that need to be suppressed, and only suppresses the oscillation modes that need to be suppressed, which can reduce the configuration requirements of the filter and achieve a better oscillation suppression effect.

[0033] For example, the set of oscillation frequencies to be suppressed is denoted as , can be represented as: ; In the formula, This is the preset damping threshold, which is typically 0.

[0034] The filtering device can use a conventional structure, as long as it includes a tunable filter structure with frequency selection function and a damping structure with damping compensation function. For example, the tunable filter structure can be any of the following: a parallel single-tuned filter, a C-type filter, a parallel RLC notch filter branch, or a variable inductor resonant branch composed of a controllable reactor, used to select the oscillation mode to be suppressed from the main line of the power system. For example, the damping structure is a resistor (any one or any combination of a series or parallel resistor network, a controllable resistor, a chopper resistor, or a controlled power electronic switch and a resistor network), used to provide compensating damping for the selected oscillation mode to be suppressed to enhance its damping ratio.

[0035] Taking an RLC band-stop filter as an example, its structure is as follows: Figure 3 As shown, in the RLC band-stop filter, the inductor L and capacitor C are connected in parallel and then in series with the resistor R. The parallel branch formed by the inductor L and capacitor C constitutes the tunable filter structure, and the resistor R is the damping structure. This RLC band-stop filter is connected to the power system as a bypass. When tuning the parameters of the RLC band-stop filter, the fundamental frequency of the power system is placed within the blocking band of the RLC band-stop filter, and the frequency of the mode to be suppressed is placed outside the blocking band of the RLC band-stop filter. When the RLC band-stop filter is connected to the power system in bypass mode, the RLC band-stop filter blocks the fundamental frequency of the power system from flowing into the bypass, allowing the fundamental frequency to flow normally in the main line, while the mode to be suppressed flows into the RLC band-stop filter, and the RLC band-stop filter enhances its damping ratio to suppress oscillations. More specifically, the fundamental frequency of the power system can be used as the center frequency of the blocking band of the RLC band-stop filter, and the half-bandwidth of the blocking band of the RLC band-stop filter should not exceed the oscillation frequency of the mode to be suppressed. It should be noted here that the oscillation frequency in the oscillation mode parameters identified in step S1 is actually the sideband component corresponding to the system's power frequency. Taking a power frequency of 60Hz as an example, for the i-th oscillation mode, its oscillation frequency is... Then the frequency of this oscillation mode is or If it is necessary to suppress the i-th oscillation mode, then 60Hz can be used as the center frequency of the blocking band of the RLC bandstop filter, and the half-bandwidth B of the blocking band satisfies: .

[0036] In this way, the fundamental frequency component of the power frequency can be guaranteed to have blocking characteristics in the filter branch, reducing the impact of the filter device on the normal power frequency operation of the system, and ensuring that the AC sideband component corresponding to the oscillation mode to be suppressed is outside the blocking band of the filter branch, so that it can flow into the filter branch and be selectively weakened.

[0037] Furthermore, during parameter tuning, the optimal parameter tuning can be determined through parameter adjustment.

[0038] For example, for an RLC bandstop filter, from the oscillation modes with a damping ratio less than or equal to zero, the oscillation mode with an oscillation frequency not lower than the feasible threshold of the half-bandwidth of the blocking band and having the minimum damping ratio is selected, and its oscillation frequency is: When tuning the parameters of the RLC band-stop filter, set the following constraints: Constraint 1: The center frequency of the blocking band of the RLC band-stop filter is the fundamental frequency of the power system; Constraint 2: The blocking band half-bandwidth of the RLC bandstop filter does not exceed ; Based on constraints, the parameters of the RLC bandstop filter are adjusted to achieve the best oscillation suppression effect.

[0039] In this embodiment, considering the limitations of the filter itself, its blocking band half-bandwidth is difficult to modulate to a very small value. That is, the RLC bandstop filter itself has a feasible threshold (minimum) for the blocking band half-bandwidth. First, it is necessary to determine which oscillation modes the filter can suppress based on hardware feasibility requirements. Then, the oscillation mode with the smallest damping ratio (largest divergence) is selected as the oscillation mode that most needs to be suppressed, based on its oscillation frequency. As the upper limit of the blocking band half-bandwidth B of the RLC bandstop filter, a blocking band half-bandwidth constraint condition is set, and parameters are tuned based on this constraint condition to achieve the best oscillation suppression effect.

[0040] S114. Connect the filter device with completed parameter tuning to the power system. The filter device filters out the oscillation components other than the fundamental wave at the AC port, realizing fast and effective suppression of wideband oscillation.

[0041] Connecting a filter to the power system can filter out and suppress oscillations outside the power frequency while maintaining the normal operating characteristics of the system at the power frequency. This allows the installed filter to suppress wideband oscillations and improve the stability of the system's small signal by providing additional compensation power beyond the fundamental power.

[0042] In one embodiment, after connecting the filtering device, the method further includes: real-time monitoring of whether the port of the filtering device provides additional compensation power; if no additional supplementary power is provided, it indicates that the current oscillation mode has disappeared, and the filtering device is disconnected; when the power system experiences an oscillation mode again, the oscillation mode parameters of the power system are re-identified and the parameters of the filtering device are adaptively tuned before the filtering device is reconnected to the power system. In other words, when the interference factors causing system oscillations disappear, the filtering device can be disconnected; when oscillations occur again, the above method is repeated to suppress the oscillations.

[0043] In general, to address the problem of broadband oscillations in new power systems with a high proportion of new energy sources and power electronic equipment, this invention first collects the system operating status, identifies oscillation mode information based on the system identification method, and then adaptively tunes the parameters of the filter device. This enables the filter device to quickly and effectively suppress complex broadband oscillations in the system by providing additional compensation power beyond the fundamental power. The filter device is installed at energy storage power stations, large-capacity new energy generator sets, or key hub nodes of the power system, thereby improving the safety and stability of the new energy power system.

[0044] Secondly, the present invention also claims a device for rapidly and effectively suppressing broadband oscillations in a new energy power system, which includes a filtering device and a control device. The filtering device includes a tunable filtering structure and a damping structure, and the control device has an acquisition module, an identification module, a parameter tuning module and an access module. The acquisition module is used to acquire the oscillation response signal of the power system under small-signal disturbance. The identification module is used to identify the system based on the oscillation response signal, determine the oscillation mode of the power system and obtain its oscillation mode parameters, including the oscillation frequency and damping ratio. The parameter tuning module is used to adaptively tune the parameters of the filter device based on the oscillation mode parameters. The filter device includes a tunable filter structure and a damping structure. The parameter tuning objective is that when the filter device is connected to the power system, it can select the oscillation mode to be suppressed and provide additional compensation power in addition to the fundamental power, thereby enhancing its damping ratio without affecting the fundamental power of the power system. The access module is used to connect the filter device with completed parameter tuning to the power system to filter out oscillation components other than the fundamental frequency, thereby achieving broadband oscillation suppression.

[0045] Furthermore, the equipment may also include a monitoring device; the monitoring device is used to monitor in real time whether the port of the filter device provides additional compensation power after the filter device is connected. If no additional supplementary power is provided, it indicates that the current oscillation mode has disappeared, so the filter device is disconnected. When the power system oscillates again, the control device is triggered to re-identify the oscillation mode parameters of the power system and adaptively tune the parameters of the filter device before reconnecting the filter device to the power system.

[0046] Each module is used to implement the corresponding steps in the above broadband oscillation suppression method. For details, please refer to the above introduction, which will not be repeated here.

[0047] The following uses a dual-fan grid-connected four-fan two-zone system as an example to verify the effectiveness of the technical solution of this invention through specific experiments.

[0048] Example 1: Oscillation suppression and verification after the outer loop saturation caused by the reactive target step, the specific steps are as follows.

[0049] (1) Establish a four-machine two-zone system model for wind turbine grid connection, set the wind turbine reactive power reference value to be subjected to step disturbance, so that the power will oscillate significantly after the disturbance; collect the active power and reactive power signals at the wind turbine grid connection point and the grid sending end or receiving end when the reactive power reference value is excited to oscillate, and identify the oscillation mode based on the collected signals through the system identification method.

[0050] The perturbation is set as follows: the PLL parameter of WT1 is set to k. p =60、k i =1400, when the system runs for 2 seconds, the reactive power reference value of WT1 is set to step, from 0.13pu to 0.

[0051] To avoid the impact of strong nonlinearity during disturbances on identification, and to take into account the problem of signal-to-noise ratio decrease after oscillation decay, this embodiment selects the system identification time window in the stage after the system starts oscillating, such as 21.5s-22.5s, and sets the downsampling factor M=5.

[0052] (2) The parameters of the filtering device are automatically designed and tuned based on the recognition results.

[0053] Table 1 below shows the identification results without a filter.

[0054]

[0055] The identification results above show that modes with low or negative damping ratios are mainly distributed in the frequency bands of 5.813 Hz, 157.821 Hz, 479.591 Hz, 965.099 Hz, 1403.774 Hz, 1620.040 Hz, and 1900.860 Hz. However, if the sideband frequency corresponding to 5.813 Hz is chosen as the upper bound of the half-bandwidth, the filter parameters will be too extreme and difficult to implement in engineering. Therefore, when designing parameters, the feasible threshold of the blocking band half-bandwidth should be considered first, and then the oscillation mode that most needs to be suppressed, i.e., 157.821 Hz with the smallest damping ratio and the largest divergence, should be selected. Therefore, the blocking band half-bandwidth should be less than this frequency, and an appropriate margin should be left in the actual tuning considering the identification error and frequency drift range. Therefore, in the design of the filter device parameters, the resonant branch parameters L and C are designed based on the center frequency of 60 Hz and the blocking bandwidth requirement, satisfying: ; ; Furthermore, based on the magnitude of the damping ratio difference to be compensated, the damping branch parameter R also needs to be tuned according to the deviation between the target mode damping ratio and the preset damping target, in order to enhance the compensation capability of the filter branch for non-fundamental oscillation power components and improve the damping ratio of the original weakly damped or negatively damped modes. Based on the above design principles, and comprehensively considering the impact of power frequency operation, the target mode frequency distribution, and the damping improvement requirements, this embodiment ultimately adopts... , , The parameter combination, the parameter tuning satisfies , .

[0056] (3) The control filter device is put into operation to suppress multi-mode oscillation components other than power frequency oscillation and improve system stability.

[0057] After the parameters are tuned, the control filter is put into operation, enabling it to selectively respond to the target oscillation frequency band, selectively suppress broadband oscillations in the system, and improve the small-signal stability of the system.

[0058] Table 2 below shows the identification results after the filter device was put into operation. It can be seen that several modes with negative damping ratios under the original unfiltered condition have turned into positive values, indicating that the parameter combination can effectively suppress the target broadband oscillation mode while minimizing the impact on the power frequency operation of the system.

[0059]

[0060] like Figure 4The figure shows the power and frequency signal waveforms of the system oscillation without the filter and the system oscillation after the filter is installed in Example 1. It can be seen that under the small signal disturbance of the reactive power reference value step, after the filter is put into operation, the damping ratio of the key unstable mode changes from negative to positive, and the system changes from unstable to stable. At the same time, the damping ratio of each oscillation mode increases compared with before the filter is put into operation, and the oscillation decays faster. Thus, the verification conclusion of "effective oscillation suppression" can be drawn.

[0061] Example 2: Oscillation suppression and verification after PLL phase step perturbation.

[0062] Example 2 shares the same system structure, filter access method, and data acquisition and processing flow as Example 1, differing only in the selection of the disturbance type and the identification time window. In Example 2, the disturbance in the simulation is set as follows: the PLL parameter of WT1 is k. p =6、k i =14. When the system runs for 2 seconds, a step perturbation is applied to the PLL phase, increasing the phase by 2π / 5, lasting for 0.1 seconds. To avoid the impact of the strong nonlinearity of the perturbation on the identification, and to take into account the problem of the signal-to-noise ratio decrease after the oscillation decays, this embodiment two selects the system identification time window in the stage where the oscillation is more obvious and relatively near linear after the perturbation ends, such as 2.3 seconds to 2.8 seconds. The same downsampling factor as in embodiment one can be used to improve the identification stability of the Matrix Pencil method.

[0063] like Figure 5 The figure shows the power and frequency signal waveforms of the system oscillation without the filter and the system oscillation after the filter is installed in Example 2. It can be seen that under the phase disturbance of the PLL, the damping ratio of each oscillation mode increases after the filter is put into operation, and the oscillation decays faster. For the modes that cause system instability or weak damping, the damping improvement is more obvious, thus drawing the verification conclusion that "oscillation suppression is effective".

[0064] Based on the above experiments, it can be seen that regardless of the type of small-signal disturbance in the power system, the present invention can identify and tune the parameters of the filtering device and connect it to the key hub node to achieve selective suppression of broadband oscillations.

[0065] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. It should be noted that the terms "in one embodiment," "for example," and "again" are intended to illustrate the present invention and are not intended to limit the present invention.

[0066] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for rapidly and effectively suppressing broadband oscillations in a new energy power system, characterized in that, include: The system acquires the oscillation response signal of the power system under small-signal disturbance excitation, performs system identification based on the oscillation response signal, determines the oscillation mode of the power system and acquires its oscillation mode parameters, including oscillation frequency and damping ratio; after determining the oscillation mode of the power system through system identification, the oscillation mode to be suppressed is selected from the oscillation modes with a damping ratio less than or equal to zero. Based on the parameters of the adaptively tuned filter device for the selected oscillation mode to be suppressed, the filter device includes a tunable filter structure and a damping structure, specifically an RLC band-stop filter. The parameter tuning objective is that when the filter device is connected to the power system, it can select the oscillation mode to be suppressed and provide additional compensation power beyond the fundamental power, thereby enhancing the damping ratio of the power system to the oscillation mode without affecting the fundamental frequency of the power system. Specifically, it makes the fundamental frequency of the power system within the blocking band of the RLC band-stop filter and makes the frequency of the mode to be suppressed outside the blocking band of the RLC band-stop filter. The filter device with completed parameter tuning is used as a hub node for bypass access to the power system. Without intervention from the controller or control loop, the RLC band-stop filter blocks the fundamental wave of the power system from flowing into the bypass, allowing the fundamental wave to flow normally in the main line, while the mode to be suppressed flows into the RLC band-stop filter. The RLC band-stop filter enhances its damping ratio to suppress oscillation, thereby filtering out oscillation components other than the fundamental wave and achieving broadband oscillation suppression. After connecting the filtering device, the method further includes: monitoring in real time whether the port of the filtering device provides additional compensation power; if no additional supplementary power is provided, it indicates that the current oscillation mode has disappeared, and then the filtering device is disconnected. When the power system experiences oscillation mode again, the oscillation mode parameters of the power system are re-identified and the parameters of the filtering device are adaptively tuned before the filtering device is reconnected to the power system.

2. The method for rapidly and effectively suppressing broadband oscillations in a new energy power system as described in claim 1, characterized in that, When tuning the parameters of the RLC bandstop filter, the fundamental frequency of the power system is used as the center frequency of the blocking band of the RLC bandstop filter, and the half-bandwidth of the blocking band of the RLC bandstop filter is made to not exceed the oscillation frequency of the oscillation mode to be suppressed.

3. The method for rapidly and effectively suppressing broadband oscillations in a new energy power system as described in claim 1, characterized in that, From the oscillation modes with a damping ratio less than or equal to zero, select the oscillation mode with an oscillation frequency not lower than the feasible threshold of the half-bandwidth of the blocking band and having the minimum damping ratio. Its oscillation frequency is: When tuning the parameters of the RLC band-stop filter, the following constraints are set: Constraint 1: The center frequency of the blocking band of the RLC band-stop filter is the fundamental frequency of the power system; Constraint 2: The blocking band half-bandwidth of the RLC bandstop filter does not exceed ; Based on the aforementioned constraints, the parameters of the RLC bandstop filter are adjusted to achieve the best oscillation suppression effect.

4. The method for rapidly and effectively suppressing broadband oscillations in a new energy power system as described in claim 1, characterized in that, The locations where the filtering device is connected in the power system include one or more of the following: large-capacity new energy generator sets, energy storage power stations, and key hub nodes in the power system that have broadband oscillation risks.

5. A device for rapidly and effectively suppressing broadband oscillations in a new energy power system, characterized in that, It includes a filtering device and a control device. The filtering device includes a tunable filter structure and a damping structure. The control device has an acquisition module, an identification module, a parameter tuning module, and an access module. The acquisition module is used to acquire the oscillation response signal of the power system under small signal disturbance. The identification module is used to identify the system based on the oscillation response signal, determine the oscillation mode of the power system and obtain its oscillation mode parameters, including the oscillation frequency and damping ratio; after determining the oscillation mode of the power system through system identification, the oscillation mode to be suppressed is selected from the oscillation modes with a damping ratio less than or equal to zero. The parameter tuning module is used to adaptively tune the parameters of the filter device based on the selected oscillation mode to be suppressed. The filter device includes a tunable filter structure and a damping structure, specifically an RLC band-stop filter. The parameter tuning objective is that when the filter device is connected to the power system, it can select the oscillation mode to be suppressed and provide additional compensation power beyond the fundamental power, thereby enhancing its damping ratio without affecting the fundamental frequency of the power system. Specifically, it makes the fundamental frequency of the power system within the blocking band of the RLC band-stop filter and makes the frequency of the mode to be suppressed outside the blocking band of the RLC band-stop filter. The access module is used to use the filter device with completed parameter tuning as a hub node for bypass access to the power system. The RLC band-stop filter blocks the fundamental wave of the power system from flowing into the bypass, allowing the fundamental wave to flow normally in the main line, while the mode to be suppressed flows into the RLC band-stop filter. The RLC band-stop filter enhances its damping ratio to suppress oscillation, thereby filtering out oscillation components other than the fundamental wave and realizing broadband oscillation suppression. It also includes a monitoring device; the monitoring device is used to monitor in real time whether the port of the filter device provides additional compensation power after the filter device is connected. If no additional supplementary power is provided, it indicates that the current oscillation mode has disappeared, and the filter device is disconnected. When the power system oscillates again, the control device is triggered to re-identify the oscillation mode parameters of the power system and adaptively tune the parameters of the filter device before reconnecting the filter device to the power system.

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