Method and device for suppressing subsynchronous oscillation of doubly-fed wind turbine

Abstract

The application relates to a double-fed fan subsynchronous oscillation suppression method and device, and relates to the field of new energy power generation; the double-fed fan subsynchronous oscillation suppression method can accurately and effectively suppress frequency oscillation of a double-fed fan, and guarantees stable operation of a system. The double-fed fan subsynchronous oscillation suppression method comprises the following steps: collecting an active power signal output by a grid-side converter of a double-fed fan in a continuous time period; calculating an instantaneous power spectral density according to the active power signal, determining a frequency cluster in which the instantaneous power spectral density exceeds a threshold value in a preset subsynchronous frequency band, and determining an oscillation main frequency from the frequency cluster; extracting a subsynchronous oscillation component based on a disturbance observer of the oscillation main frequency, the active power signal and a plurality of narrow-band resonance signals; calculating a compensation power component of photovoltaic power generation equipment according to the subsynchronous oscillation component, and controlling the photovoltaic power generation equipment to output a compensation power signal according to the compensation power component.

Description

Technical Field

[0001] This application relates to the field of new energy power generation, and in particular to a method and apparatus for suppressing subsynchronous oscillations in a doubly fed wind turbine. Background Technology

[0002] Doubly-fed induction generators (DFIGs) have become the mainstream technology for wind power generation due to their variable-speed, constant-frequency characteristics and cost advantages. However, when DFIG wind turbines are connected to a weak grid via series compensation capacitors, subsynchronous resonance or subsynchronous control interactions can easily occur between them and the grid. Such oscillations can lead to decreased turbine operating stability, accelerated equipment fatigue wear, and in severe cases, may cause large-scale grid disconnection, posing a threat to the safe operation of the power grid.

[0003] Existing subsynchronous oscillation suppression technologies each have certain limitations: solutions based on energy storage devices are expensive, and the charge-discharge life of energy storage devices is limited, which is not conducive to large-scale applications; hardware solutions (such as additional subsynchronous damping controllers, static synchronous compensators, etc.) require additional equipment investment, increasing system complexity and operation and maintenance costs, and parameter tuning is complicated; control strategy optimization (such as improving rotor-side converter vector control) is only effective for specific oscillation modes, making it difficult to cover wide-band risks, and does not fully consider the coupling effect between DC-side voltage fluctuations and oscillations.

[0004] With the rapid development of the new energy industry, the combined grid connection of photovoltaic power plants and wind farms is becoming increasingly common. Photovoltaic arrays are connected to the grid via power electronic devices, offering advantages such as fast response and flexible power regulation. However, current technologies do not fully utilize these characteristics of photovoltaic power generation equipment to suppress subsynchronous oscillations in doubly-fed induction generator (DFIG) wind turbines. Even when some approaches mention photovoltaic power regulation, they fail to deeply integrate the dynamic controllability of photovoltaic load shedding into the power cancellation logic design, and they do not address the cancellation deviation caused by dynamic changes in oscillation parameters. Consequently, the regulation potential of photovoltaics is not fully realized, making it difficult to achieve stable and efficient oscillation suppression. Summary of the Invention

[0005] This application provides a method and apparatus for suppressing subsynchronous oscillations in a doubly fed wind turbine, which can eliminate subsynchronous oscillations with high precision and stability.

[0006] In a first aspect, this application provides a method for suppressing subsynchronous oscillations in a doubly-fed wind turbine, comprising:

[0007] Collect the active power signal output from the grid-side converter of the doubly-fed wind turbine over a continuous time period;

[0008] The instantaneous power spectral density is calculated based on the active power signal, and the frequency clusters in which the instantaneous power spectral density exceeds the threshold within the preset subsynchronous frequency band are identified. The oscillation main frequency is then determined from the frequency clusters.

[0009] Based on the disturbance observer of the oscillation master frequency, active power signal and multiple narrowband resonance signals, the subsynchronous oscillation component is extracted;

[0010] The compensation power component of the photovoltaic power generation equipment is calculated based on the subsynchronous oscillation component, and the output compensation power signal of the photovoltaic power generation equipment is controlled based on the compensation power component.

[0011] In the method provided in this embodiment, the subsynchronous periodic disturbance in the instantaneous active power on the grid-connected side is modeled as a multi-narrowband resonant signal. The photovoltaic power generation equipment estimates the subsynchronous oscillation component in real time based on the disturbance observer of the multi-band quasi-resonant internal mode. By actively introducing the corresponding dynamic compensation component into the output power, the system forms an energy cancellation effect in the subsynchronous frequency band, thereby effectively suppressing the oscillation energy. No modification to the original wind turbine structure is required; photovoltaic-side control optimization is sufficient, making the modification difficult. Furthermore, the suppression mode is switched only during oscillation, maintaining maximum photovoltaic power output at other times, resulting in minimal losses.

[0012] Secondly, this application provides a subsynchronous oscillation suppression device for a doubly-fed wind turbine, comprising:

[0013] The signal acquisition module is used to acquire the active power signal output by the grid-side converter of the doubly fed wind turbine over a continuous time period.

[0014] The oscillation frequency band extraction module is used to calculate the instantaneous power spectral density based on the active power signal, determine the frequency clusters in the preset subsynchronous frequency band where the instantaneous power spectral density exceeds a threshold, and determine the oscillation main frequency from the frequency clusters.

[0015] The subsynchronous component extraction module is used to extract the subsynchronous oscillation component based on the disturbance observer of the oscillation main frequency, active power signal and multiple narrowband resonance signal;

[0016] The photovoltaic compensation module is used to calculate the compensation power component of the photovoltaic power generation equipment based on the subsynchronous oscillation component, and to control the output compensation power signal of the photovoltaic power generation equipment based on the compensation power component.

[0017] Thirdly, this application provides an electronic device including a memory and one or more processors. The memory stores one or more computer programs, each including instructions that, when executed by the processor, cause the electronic device to perform the doubly-fed fan subsynchronous oscillation suppression method as described in the first aspect.

[0018] Fourthly, this application provides a computer-readable storage medium storing instructions that, when executed on an electronic device, cause the electronic device to perform the doubly-fed fan subsynchronous oscillation suppression method as described in the first aspect.

[0019] Fifthly, this application provides a computer program product that, when run on an electronic device, causes the electronic device to perform the doubly fed fan subsynchronous oscillation suppression method as described in the first aspect.

[0020] Understandably, the beneficial effects achieved by the doubly fed wind turbine subsynchronous oscillation suppression device, electronic equipment, computer-readable storage medium, and computer program product provided above can be referred to the beneficial effects in the first aspect, and will not be repeated here. Attached Figure Description

[0021] Figure 1 A schematic diagram of the system architecture for the doubly fed wind turbine subsynchronous oscillation suppression method provided in this application embodiment;

[0022] Figure 2 This is a flowchart illustrating the method for suppressing subsynchronous oscillations of a doubly-fed wind turbine provided in an embodiment of this application.

[0023] Figure 3 This is a flowchart illustrating the process of determining the dominant oscillation frequency in the doubly fed wind turbine subsynchronous oscillation suppression method provided in this application embodiment;

[0024] Figure 4 This is a flowchart illustrating the method for suppressing subsynchronous oscillations of a doubly-fed wind turbine provided in this application embodiment, showing the process of determining the compensation power component.

[0025] Figure 5 Another flowchart of the doubly fed fan subsynchronous oscillation suppression method provided in the embodiments of this application;

[0026] Figure 6 This is a schematic diagram of the structure of the doubly fed fan subsynchronous oscillation suppression device provided in the embodiments of this application;

[0027] Figure 7 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0028] To facilitate a clear description of the technical solutions in the embodiments of this application, the terms "first" and "second" are used in the embodiments of this application to distinguish identical or similar items with substantially the same function and effect. For example, "first chip" and "second chip" are only used to distinguish different chips and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and the terms "first" and "second" do not necessarily imply that they are different. It should be noted that in the embodiments of this application, the words "exemplary" or "for example" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design scheme described as "exemplary" or "for example" in this application should not be construed as being better or more advantageous than other embodiments or design schemes. Specifically, the use of the words "exemplary" or "for example" is intended to present the relevant concepts in a specific manner. In the embodiments of this application, "at least one" means one or more, and "more than one" means two or more.

[0029] It should be noted that "at the time of..." in the embodiments of this application can be either at the instant when a certain situation occurs, or for a period of time after the occurrence of a certain situation. The embodiments of this application do not make specific limitations on this.

[0030] The implementation of this embodiment will now be described in detail with reference to the accompanying drawings.

[0031] This embodiment provides a method for suppressing subsynchronous oscillations in a doubly-fed induction generator (DFIG) wind turbine. For example, this method can be applied to photovoltaic power generation equipment in a grid-connected system.

[0032] Figure 1 The system architecture of the doubly-fed wind turbine subsynchronous oscillation suppression method provided in this application embodiment is illustrated. For example... Figure 1 As shown, the system includes photovoltaic (PV) power generation equipment and a doubly-fed induction generator (DFIG), which are connected to the grid-side converter via a rotor-side converter and a PV converter to form a grid-connected system. Under normal conditions, the PV power generation equipment operates at maximum power through maximum power point tracking (MPPT). When the PV power generation equipment detects subsynchronous oscillations, it switches to oscillation suppression mode, outputting a corresponding compensation power signal based on the subsynchronous oscillation component to offset the oscillation power and achieve stable and reliable system operation.

[0033] Figure 2 A flowchart illustrating the method for suppressing subsynchronous oscillations of a doubly fed wind turbine provided in an embodiment of this application is shown.

[0034] like Figure 2 As shown, the method for suppressing subsynchronous oscillations in a doubly-fed wind turbine may include the following steps:

[0035] Step 101: Collect the active power signal output by the grid-side converter of the doubly fed wind turbine over a continuous time period.

[0036] In this embodiment, the monitoring of the active power signal output by the grid-side converter of the doubly-fed induction generator (DFIG) is real-time and continuous, including during normal operation and when subsynchronous oscillations occur. For example, a sampling frequency of 10kHz is used. Synchronous acquisition of active power output from grid-side converter The mechanical speed R of the doubly fed wind turbine rotor and the voltage signal at the grid connection point on the power grid side. This provides data for monitoring subsynchronous oscillations.

[0037] Furthermore, under normal operating conditions, the photovoltaic power generation equipment uses the perturbation observation method to achieve maximum power point tracking (MPPT) and operates at maximum output power, reserving a power adjustment margin for oscillation suppression.

[0038] After obtaining the active power signal, it can be preprocessed using a smoothing filter to facilitate subsequent calculations.

[0039] Step 102: Calculate the instantaneous power spectral density based on the active power signal, determine the frequency clusters in the preset subsynchronous frequency band where the instantaneous power spectral density exceeds the threshold, and determine the oscillation main frequency from the frequency clusters.

[0040] In this embodiment, the instantaneous power spectral density is used to determine whether the system is experiencing subsynchronous oscillation. If the instantaneous power spectral density exceeds a threshold, i.e., a significant peak appears, then subsynchronous oscillation is confirmed. Next, the stability of the oscillation master frequency is determined to obtain a stable oscillation master frequency. The calculation process of the instantaneous power spectral density is as follows: after preprocessing the active power signal through a smoothing filter, a short-time Fourier transform is performed on the preprocessed active power signal to obtain the time-frequency complex amplitude, and the instantaneous power spectral density is calculated based on the time-frequency complex amplitude. The process of determining the oscillation master frequency is as follows: within a preset subsynchronous frequency band (corresponding to the angular frequency range)... The search power spectral density within the range exceeds the threshold. If, within a certain number of consecutive time periods, the difference between the angular frequencies in the angular frequency cluster of the i-th sliding window and the angular frequencies in the angular frequency cluster of the (i-1)-th sliding window is less than a preset value, then the system's oscillation main frequency is determined to be stable, and the angular frequency at this point is the oscillation main frequency. The duration of the sliding window can be preset according to actual needs.

[0041] In an exemplary embodiment, an active power signal is output to the grid-side converter according to a set time period. Sliding Short-Time Fourier Transform (SSTFT) can be performed if it is within the set subsynchronous angular frequency range. Short-time power spectral density A significant peak value appeared, and its amplitude exceeded the preset threshold. At the same time, the same angular frequency was detected in the rotor mechanical speed signal of the doubly fed wind turbine and the voltage signal at the grid connection point on the grid side collected at the same time. If the oscillation component is detected, it is determined that the system is experiencing subsynchronous oscillation. At this point, the control system switches to oscillation suppression mode and initiates the active load shedding and power cancellation process for the photovoltaic power generation units, referring to... Figure 3 The specific implementation steps are as follows:

[0042] a) Real-time acquisition of voltage signals from the grid connection point on the power grid side and current signal Calculate the instantaneous active power signal Sampling frequency Sampling interval time To reduce the impact of noise, a smoothing filter can be used first. Preprocess the signal:

[0043] (1)

[0044] in This is a convolution operation.

[0045] b) To analyze the energy distribution of the power signal in the time and angular frequency domains, Perform STFT conversion:

[0046] (2)

[0047] in A window function used to limit the range of time analysis; The time-frequency complex amplitude reflects the power signal at angular frequency. Local components at that location.

[0048] c) Calculate the instantaneous power spectral density:

[0049] (3)

[0050] This quantity represents the power signal at different times. and frequency The energy distribution below.

[0051] d) In the preset subsynchronous frequency band (corresponding to the angular frequency range) Search for the angular frequency clusters whose power spectral density exceeds the threshold within the range:

[0052] (4)

[0053] in If the following conditions are met for several consecutive time periods:

[0054] (5)

[0055] Then the system oscillation frequency is considered to be the dominant frequency. Stable, where i represents the i-th sliding window. This is the default value.

[0056] Step 103: Extract the subsynchronous oscillation component based on the disturbance observer of the oscillation master frequency, active power signal and multiple narrowband resonance signals.

[0057] In this embodiment, it is first necessary to construct a disturbance observer for multiple narrowband resonant signals; input the oscillation main frequency and the preprocessed active power signal into the disturbance observer to obtain state variable estimates; determine the amplitude estimate and phase estimate through the state variable estimates, and determine the subsynchronous oscillation component based on the amplitude estimate and phase estimate.

[0058] The disturbance observer is:

[0059]

[0060] in,

[0061] The dominant oscillation frequency, State variable estimates The differential, This is the preprocessed active power signal; The internal model matrix, Here is the gain matrix. For the resonant bandwidth, Let k be the harmonic order, and k be the output matrix. The estimated state variables are expressed as:

[0062]

[0063] in, This is the amplitude estimate. This is the phase estimate. , These are the two components of the estimated value of the state variable.

[0064] In this embodiment, under oscillation suppression mode, relying on the fast response speed of photovoltaic equipment, the active load shedding mechanism introduces a dynamic compensation component conjugate to the target fluctuation component into the output power of the doubly-fed wind turbine through a disturbance observer of a multi-band quasi-resonant internal mode. An adaptive disturbance observation law is then used to dynamically calibrate the amplitude and phase of the compensation power fluctuation to ensure cancellation accuracy. The specific derivation process is as follows:

[0065] a) First, model the oscillation signal and design the disturbance observer, modeling the active power signal at the grid connection point as the sum of steady-state power and multiple narrowband resonant disturbances:

[0066] (6)

[0067] The steady-state power during the disturbance, For the target oscillation component, satisfying:

[0068] (7)

[0069] To estimate the amplitude and phase Design a perturbation observer with multiple band quasi-resonant internal modes. Construct the state variables for the k-th harmonic perturbation signal. as follows:

[0070]

[0071] The estimated value of this state variable is :

[0072]

[0073] The disturbance observer equation for a certain harmonic is constructed as follows:

[0074] (8)

[0075] in, Contains an internal model matrix. Gain matrix, The output matrices are as follows:

[0076] (9)

[0077] This is the resonant bandwidth.

[0078] This structure can operate in steady state at frequencies of... Zero steady-state error observation is achieved by observing the resonance disturbances in and around the affected area. Finally, the subsynchronous oscillation component can be estimated, calculated as follows:

[0079] (10)

[0080] in, , These are the estimated amplitude and phase values, respectively, where k represents the harmonic order and N is the total number of harmonics. This is an estimate of the subsynchronous oscillation component.

[0081] Step 104: Calculate the compensation power component of the photovoltaic power generation equipment based on the subsynchronous oscillation component, and control the output compensation power signal of the photovoltaic power generation equipment based on the compensation power component.

[0082] The output compensation power signal of the photovoltaic power generation equipment is set as follows:

[0083] (11)

[0084] in, This represents the maximum output power under maximum power point tracking. The compensation power component is used for oscillation suppression; compensation commands are generated based on the estimates from the disturbance observer.

[0085] (12)

[0086] in The compensation ratio is k, where k is the harmonic order and N is the total number of harmonics. This means that the photovoltaic output is superimposed with a fluctuation of equal amplitude and opposite phase to the target oscillation component on top of the original power, thus canceling out power oscillations in the power grid.

[0087] During the estimation of subsynchronous oscillation components by the disturbance observer, when frequency drift occurs, the dominant oscillation frequency in the disturbance observer is adjusted according to the following formula:

[0088]

[0089] Where n is the discrete time step. Let n be the step size factor, and e(n) be the residual oscillation component. This represents the sampling time interval.

[0090] This maintains resonance locking and enables adaptive tracking of changes in the oscillation frequency, whereby... .

[0091] After the photovoltaic power generation equipment outputs a compensation power signal, this embodiment further includes: calculating the power oscillation energy based on the grid's output power after the photovoltaic power generation equipment outputs the compensation power signal; periodically applying a perturbation to the amplitude and phase of the compensation signal based on an adaptive calibration law, and calculating the perturbed power oscillation energy; if the perturbed power oscillation energy is less than the pre-perturbation power oscillation energy, the perturbation continues to adjust in the same direction; if the perturbed power oscillation energy is not less than the pre-perturbation power oscillation energy, the perturbation is adjusted in the opposite direction. The power oscillation energy is calculated using the following formula:

[0092]

[0093] The sampling time interval, And m are discrete time steps. Let be the window length, and e be the residual oscillation component, which is obtained by subtracting the average power from the actual power connected to the grid.

[0094] The adaptive calibration law is:

[0095]

[0096] in, For discrete time steps, and Step size factor This is the amplitude estimate. For the phase estimate, J( ) represents the amplitude component of the power oscillation energy, J( ) represents the phase component of the power oscillation energy, and k represents the harmonic order.

[0097] In practical systems, issues such as communication delays, filter phase shifts, model uncertainties, and oscillation frequency drift can lead to… and The estimation bias is addressed. To maintain compensation accuracy, an adaptive calibration law based on the perturbation observation method is introduced to achieve dynamic online correction of amplitude and phase.

[0098] Suppose the residual oscillation component measured by the power grid is:

[0099] (13)

[0100] Ideally The discretized power oscillation energy is defined as:

[0101] (14)

[0102] in The sampling time interval, For discrete time steps, The window length is used to balance response and stability, and the function value represents the cancellation effect.

[0103] By using the perturbation observation method, the amplitude of the compensation signal is periodically adjusted. With phase Apply a perturbation, in which , As the step size factor, this law guarantees... Monotonically decreasing, achieving convergence of amplitude and phase:

[0104] (15)

[0105] Calculate the new oscillation energy ,like If so, the perturbation continues to adjust in the same direction; if If the correction occurs in the opposite direction, this process can be described as a discrete adaptive law.

[0106] The above power compensation process is as follows: Figure 4 As shown, overall, the main oscillation frequency is obtained by extracting subsynchronous oscillation angular frequency clusters. The active power signal and oscillation main frequency The input perturbation observer estimates the amplitude and phase, and then the amplitude and phase are perturbed by an adaptive perturbation observation law to correct the photovoltaic compensation power. This allows for automatic adjustment of amplitude and phase in the event of changes in system parameters or the presence of delays, thereby achieving accurate and effective oscillation suppression.

[0107] Continuously monitor the active power signal on the grid side. If it is determined that there is no significant peak in the subsynchronous frequency band, or monitor the rotor mechanical speed R and the voltage signal at the grid connection point on the grid side. When the subsynchronous components of the two components fall below a set level and remain below that level for a preset duration, the subsynchronous oscillation is considered to have subsided. Once the subsynchronous oscillation has subsided, the system switches from oscillation suppression mode back to normal operation mode, the photovoltaic equipment stops introducing power compensation signals, and resumes maximum power output operation.

[0108] The method described in this embodiment requires no additional hardware or high-cost energy storage, and relies on coordinated solar and wind control to reduce costs. SSTFT can overcome the disadvantage of FFT in accurately capturing the spectral information of non-steady-state signals. The perturbation observer with multi-band resonant internal modes can accurately lock and track multi-frequency narrowband power oscillation signals. The adaptive perturbation calibration law can automatically adjust amplitude and phase under system parameter changes and delays, achieving continuous and effective power cancellation. The closed-loop structure combining perturbation observation and adaptive law can maintain the accuracy of oscillation detection and cancellation under conditions of frequency drift and parameter uncertainty.

[0109] Figure 5 A flowchart illustrating an exemplary embodiment of this application is shown, such as... Figure 5 As shown, the photovoltaic power generation equipment performs the following steps:

[0110] Step 1: Normal Operation Mode. In normal operation mode, the photovoltaic system operates according to MPPT, and the system output active power signal is periodically monitored. Fan speed R and grid connection voltage .

[0111] Step 2: Use SSTFT to extract the angular frequency clusters of the subsynchronous components that exceed the threshold.

[0112] Step 3: Oscillation Suppression Mode. Oscillation Suppression Mode: Through the perturbation observer of the multi-band quasi-resonant internal mode and the adaptive perturbation observer law, the photovoltaic load reduction introduces power compensation to cancel the subsynchronous component.

[0113] Step 4: Continuously monitor the fan speed R and the grid connection voltage. The subsynchronous component.

[0114] Step 5: Determine if the subsynchronization component has recovered and stabilized for a period of time. If not, return to step 4; otherwise, proceed to step 6.

[0115] Step 6: Restore normal operation mode, and stop the photovoltaic equipment from introducing power compensation fluctuations.

[0116] Furthermore, this embodiment also provides a doubly-fed induction fan subsynchronous oscillation suppression device, which can be used to execute the above-described doubly-fed induction fan subsynchronous oscillation suppression method. For example... Figure 6 As shown, the doubly-fed induction generator (DFIG) subsynchronous oscillation suppression device 400 specifically includes: a signal acquisition module 401, used to acquire the active power signal output by the grid-side converter of the DFIG over a continuous time period; an oscillation frequency band extraction module 402, used to calculate the instantaneous power spectral density based on the active power signal, determine the frequency clusters whose instantaneous power spectral density exceeds a threshold within a preset subsynchronous frequency band, and determine the oscillation main frequency from the frequency clusters; a subsynchronous component extraction module 403, used to extract the subsynchronous oscillation component based on the oscillation main frequency, the active power signal, and a disturbance observer with multiple narrowband resonant signals; and a photovoltaic compensation module 404, used to calculate the compensation power component of the photovoltaic power generation equipment based on the subsynchronous oscillation component, and control the output of the compensation power signal of the photovoltaic power generation equipment based on the compensation power component.

[0117] The specific details of each module or unit in the aforementioned doubly fed fan subsynchronous oscillation suppression device have been described in detail in the corresponding doubly fed fan subsynchronous oscillation suppression method, so they will not be repeated here.

[0118] This application also provides an electronic device. Figure 7 A schematic diagram of the structure of an electronic device suitable for implementing embodiments of the present disclosure is shown. Figure 7 The electronic device 600 shown is merely an example and should not be construed as limiting the functionality and scope of use of the embodiments disclosed herein.

[0119] like Figure 7As shown, the electronic device 600 includes a central processing unit (CPU) 601, which can perform various appropriate actions and processes based on a program stored in a read-only memory (ROM) 602 or a program loaded from a storage section 608 into a random access memory (RAM) 603. The RAM 603 also stores various programs and data required for system operation. The CPU 601, ROM 602, and RAM 603 are interconnected via a bus 604. An input / output (I / O) interface 605 is also connected to the bus 604.

[0120] The following components are connected to I / O interface 605: an input section 606 including a keyboard, mouse, etc.; an output section 607 including a cathode ray tube (CRT), liquid crystal display (LCD), etc., and speakers, etc.; a storage section 608 including a hard disk, etc.; and a communication section 609 including a network interface card such as a LAN card, modem, etc. The communication section 609 performs communication processing via a network such as the Internet. A drive 610 is also connected to I / O interface 605 as needed. A removable medium 611, such as a disk, optical disk, magneto-optical disk, semiconductor memory, etc., is installed on drive 610 as needed so that computer programs read from it can be installed into storage section 608 as needed.

[0121] In particular, according to embodiments of this disclosure, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this disclosure include a computer program product comprising a computer program carried on a computer-readable storage medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication section 609, and / or installed from removable medium 611. When the computer program is executed by central processing unit (CPU) 601, it performs the functions defined in the embodiments of this application.

[0122] For example, when the computer program is executed by the central processing unit (CPU) 601, it can perform the following: acquire the active power signal output by the grid-side converter of the doubly-fed wind turbine over a continuous time period; calculate the instantaneous power spectral density based on the active power signal, determine the frequency clusters in the preset subsynchronous frequency band where the instantaneous power spectral density exceeds a threshold, and determine the oscillation main frequency from the frequency clusters; extract the subsynchronous oscillation component based on the oscillation main frequency, the active power signal, and the disturbance observer of the multi-narrowband resonant signal; calculate the compensation power component of the photovoltaic power generation equipment based on the subsynchronous oscillation component, and control the output of the compensation power signal of the photovoltaic power generation equipment based on the compensation power component.

[0123] It should be noted that the computer-readable medium disclosed herein may be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium may be, for example,—but not limited to—an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this disclosure, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this disclosure, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media can also be any computer-readable medium other than computer-readable storage media, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0124] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram or flowchart, and combinations of blocks in a block diagram or flowchart, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0125] The units described in the embodiments of this disclosure can be implemented in software or hardware, and the described units can also be located in a processor. The names of these units do not necessarily limit the unit itself.

[0126] In another aspect, this application also provides a computer-readable medium, which may be included in the electronic device described in the above embodiments; or it may exist independently and not assembled into the electronic device. The computer-readable medium carries one or more programs, which include instructions that, when executed by the electronic device, cause the electronic device to perform the methods described in the above embodiments.

[0127] It should be noted that although several modules or units for the device used to perform actions have been mentioned in the detailed description above, this division is not mandatory. In fact, according to the embodiments of this application, the features and functions of two or more modules or units described above can be embodied in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided and embodied by multiple modules or units.

[0128] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for suppressing subsynchronous oscillations in a doubly-fed wind turbine, characterized in that, include: Collect the active power signal output from the grid-side converter of the doubly-fed wind turbine over a continuous time period; The instantaneous power spectral density is calculated based on the active power signal, and the frequency clusters in which the instantaneous power spectral density exceeds the threshold within the preset subsynchronous frequency band are identified. The oscillation main frequency is then determined from the frequency clusters. Based on the disturbance observer of the oscillation master frequency, active power signal and multiple narrowband resonance signals, the subsynchronous oscillation component is extracted; The compensation power component of the photovoltaic power generation equipment is calculated based on the subsynchronous oscillation component, and the output compensation power signal of the photovoltaic power generation equipment is controlled based on the compensation power component. The extraction of subsynchronous oscillation components based on the dominant oscillation frequency, active power signal, and disturbance observer includes: Construct a disturbance observer for multiple narrowband resonant signals; The oscillation frequency and the preprocessed active power signal are input into the disturbance observer to obtain the estimated values ​​of the state variables; The disturbance observer is: in, The dominant oscillation frequency, State variable estimates The differential, This is the preprocessed active power signal; The internal model matrix, Here is the gain matrix. For the resonant bandwidth, This is the output matrix, where k is the harmonic order; The amplitude and phase estimates are determined by estimating the state variables, and the subsynchronous oscillation components are determined based on the amplitude and phase estimates. The estimated values ​​of the state variables are expressed as follows: in, This is the amplitude estimate. This is the phase estimate. , These are the two components of the estimated value of the state variable.

2. The method for suppressing subsynchronous oscillations of a doubly-fed wind turbine according to claim 1, characterized in that, The calculation of instantaneous power spectral density based on active power includes: The active power signal is preprocessed using a smoothing filter; The preprocessed active power signal is subjected to a sliding short-time Fourier transform to obtain the time-frequency complex amplitude, and the instantaneous power spectral density is calculated based on the time-frequency complex amplitude.

3. The method for suppressing subsynchronous oscillations of a doubly-fed wind turbine according to claim 1, characterized in that, The subsynchronous oscillation component is: k represents the harmonic order, and N represents the total number of harmonics.

4. The method for suppressing subsynchronous oscillations of a doubly-fed wind turbine according to claim 1, characterized in that, The step of controlling the output of the photovoltaic power generation equipment based on the compensated power component includes: The compensation power signal of a photovoltaic power generation device is determined by the compensation power component, using the following formula: in, This represents the maximum output power under maximum power point tracking. To compensate for the power component; The compensated power component is: is the compensation ratio coefficient; k is the harmonic order, and N is the total number of harmonics.

5. The method for suppressing subsynchronous oscillations of a doubly-fed wind turbine according to claim 1, characterized in that, Also includes: When frequency drift occurs, the dominant oscillation frequency in the disturbance observer is adjusted according to the following formula: Where n is the discrete time step. Let n be the step size factor, and e(n) be the residual oscillation component. This represents the sampling time interval.

6. The method for suppressing subsynchronous oscillations of a doubly-fed wind turbine according to claim 1, characterized in that, After controlling the output compensation power signal of the photovoltaic power generation equipment according to the compensation power component, it also includes: Calculate the power oscillation energy based on the output power of the power grid after the photovoltaic power generation equipment outputs the compensation power signal; Based on the periodicity of the adaptive calibration law, a perturbation is applied to the amplitude and phase of the compensation signal, and the power oscillation energy after the perturbation is calculated. If the power oscillation energy after the disturbance is less than the power oscillation energy before the disturbance, the perturbation continues to adjust in the same direction; if the power oscillation energy after the disturbance is not less than the power oscillation energy before the disturbance, the perturbation adjusts in the opposite direction.

7. The method for suppressing subsynchronous oscillations of a doubly-fed wind turbine according to claim 6, characterized in that, The power oscillation energy is calculated using the following formula: The sampling time interval, For discrete time steps, Let be the window length, and e be the residual oscillation component, which is obtained by subtracting the average power from the actual power connected to the grid.

8. The method for suppressing subsynchronous oscillations of a doubly-fed wind turbine according to claim 6, characterized in that, The adaptive calibration law is: in, For discrete time steps, All are step size factors. This is the amplitude estimate. For the phase estimate, J( ) represents the amplitude component of the power oscillation energy, J( ) represents the amplitude component of the power oscillation energy, and k represents the harmonic order.

9. A doubly-fed fan subsynchronous oscillation suppression device, characterized in that, include: The signal acquisition module is used to acquire the active power signal output by the grid-side converter of the doubly fed wind turbine over a continuous time period. The oscillation frequency band extraction module is used to calculate the instantaneous power spectral density based on the active power signal, determine the frequency clusters in the preset subsynchronous frequency band where the instantaneous power spectral density exceeds a threshold, and determine the oscillation main frequency from the frequency clusters. The subsynchronous component extraction module is used to extract the subsynchronous oscillation component based on the disturbance observer of the oscillation main frequency, active power signal and multiple narrowband resonance signal; The photovoltaic compensation module is used to calculate the compensation power component of the photovoltaic power generation equipment based on the subsynchronous oscillation component, and control the output compensation power signal of the photovoltaic power generation equipment based on the compensation power component. The extraction of subsynchronous oscillation components based on the dominant oscillation frequency, active power signal, and disturbance observer includes: Construct a disturbance observer for multiple narrowband resonant signals; The oscillation frequency and the preprocessed active power signal are input into the disturbance observer to obtain the estimated values ​​of the state variables; The disturbance observer is: in, The dominant oscillation frequency, State variable estimates The differential, This is the preprocessed active power signal; The internal model matrix, Here is the gain matrix. For the resonant bandwidth, This is the output matrix, where k is the harmonic order; The amplitude and phase estimates are determined by estimating the state variables, and the subsynchronous oscillation components are determined based on the amplitude and phase estimates. The estimated values ​​of the state variables are expressed as follows: in, This is the amplitude estimate. This is the phase estimate. , These are the two components of the estimated value of the state variable.

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