Fan paddle adjusting compensation damping control system and method for ultralow frequency oscillation suppression

Abstract

The invention discloses a fan pitch adjustment compensation damping control system and method for ultralow frequency oscillation suppression, and the system comprises a wind turbine generator primary frequency modulation control module and an additional damping controller, and the additional damping controller is connected with the wind turbine generator primary frequency modulation control module in parallel and then is connected into a pitch angle compensation control system; the additional damping controller comprises a power grid frequency monitoring and low-pass filtering module, an additional damping controller gain adjusting module, an isolation direct current module and a frequency control signal phase compensation module which are sequentially connected in series. The additional damping controller is connected to the primary frequency modulation position of the draught fan in parallel to suppress the ultralow frequency oscillation behavior of the water-wind combined system, the power output active power is changed through dynamic paddle adjustment, and therefore power oscillation of the ultralow frequency band is suppressed.

Description

Technical Field

[0001] The present invention relates to the technical field of stability control of new energy power systems, and in particular to a wind turbine pitch adjustment compensation damping control system and method for ultra-low frequency oscillation suppression. Background Art

[0002] In the common wind and water combined systems currently in use, the turbine speed governor introduces negative damping to the system in frequency oscillation modes due to the water hammer effect, making frequency oscillations, especially those below 0.1Hz, increasingly prominent. Ultra-low frequency oscillations are particularly prominent in Yunnan Province, my country, due to the high proportion of hydropower and asynchronous grid-connected operation. The current market mainstream involves installing damping suppression devices on the turbine side. However, the turbine speed control system is affected by the delay in guide vane movement and the water hammer effect, resulting in a system dynamic response rate significantly lower than the dynamic requirements, making it difficult to achieve synchronous compensation for oscillation phases. The anti-peaking effect generated during rapid power regulation can easily form a positive feedback mechanism between the regulated power and system disturbances, potentially triggering a reverse regulation phenomenon in which the power fluctuation amplitude doubles, posing a significant challenge to the frequency security and stability of the power system.

[0003] Due to their instability, hydro-wind combined power generation systems often experience ultra-low frequency oscillations. Currently, power systems typically suppress frequency oscillations by attaching a GPS system to the turbine, such as the solution proposed in Patent No. CN111030136A, which installs a hydro-turbine speed governor and power system stabilizer. Alternatively, methods for suppressing ultra-low frequency oscillations on the wind turbine side include an additional damping control method and system that utilizes the wind turbine's rotor kinetic energy to suppress ultra-low frequency oscillations, such as the solution proposed in Patent No. CN117175629A. While both solutions can suppress ultra-low frequency oscillations to a certain extent, they both have drawbacks. The "water hammer effect" inherently exists during turbine regulation, and the addition of a GPS system can further exacerbate this effect by adjusting the turbine's guide vane opening. GPS systems suppress ultra-low frequency oscillations by adjusting the guide vane opening. However, rapid changes in water flow during regulation can easily trigger or amplify water hammer. The turbine's guide vanes have limited response speed due to their mechanical structure and hydraulic actuators. When the GPSS device issues an adjustment signal, the guide vane blades are unable to move in a timely and accurate manner according to the control requirements, resulting in adjustment lag. When ultra-low frequency oscillations need to be quickly suppressed, this delay reduces the control effectiveness of the GPSS device, making it impossible to adjust the grid frequency in a timely and effective manner. After the GPSS device is put into operation, its adjustment of the guide vane opening may, in some cases, aggravate the reverse peak regulation situation and affect the stable power supply of the grid. Traditional wind turbine speed control relies on rotor kinetic energy to suppress frequency oscillations. However, the controllable rotor kinetic energy of the wind turbine is limited, resulting in limited suppression of system frequency oscillations. Faced with more complex or strong frequency oscillations, it is impossible to quickly and effectively suppress the oscillations within the ideal range.

[0004] Patent No. CN117175716A, "A Method and System for Additional Reactive Power Control to Improve the Frequency Regulation Response of Doubly Fed Wind Turbines," optimizes frequency regulation response through additional control of the reactive power control loop. This approach is only applicable to access scenarios where frequency is highly sensitive to reactive power. Patent No. CN116137444A, "A Method and System for Additional Active Power Control of Doubly Fed Wind Turbines to Optimize System Frequency Response," primarily improves the dynamic performance of system frequency response and suppresses the maximum deviation of system frequency oscillations. Patent No. CN115622149A, "A Method and System for Modeling System Frequency Response of Doubly Fed Wind Turbines Participating in Primary Frequency Regulation," focuses on establishing frequency response models and analysis methods. These three methods differ significantly from the present invention in terms of technical approaches, goals, and priorities. Summary of the Invention

[0005] In response to the above-mentioned technical deficiencies, the purpose of the present invention is to provide a wind turbine pitch adjustment compensation damping control system and method for ultra-low frequency oscillation suppression, and to connect an additional damping controller in parallel at the primary frequency regulation point of the wind turbine to suppress the ultra-low frequency oscillation behavior of the water-wind combined system, and to change the active power output through dynamic pitch adjustment, thereby suppressing power oscillations in the ultra-low frequency band.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions: a wind turbine pitch compensation damping control system for ultra-low frequency oscillation suppression, including a wind turbine primary frequency regulation control module, and also including an additional damping controller, the additional damping controller is connected in parallel with the wind turbine primary frequency regulation control module and connected to the pitch angle compensation control system; the additional damping controller includes a grid frequency monitoring and low-pass filtering module, an additional damping controller gain adjustment module, an isolated DC module and a frequency control signal phase compensation module connected in series in sequence, the grid frequency monitoring and low-pass filtering module is used for frequency monitoring and low-pass filtering, the additional damping controller gain adjustment module is used for gain adjustment, the isolated DC module is used for isolating the DC component, and the frequency control signal phase compensation module is used for frequency control signal phase compensation.

[0007] The pitch angle compensation control structure also includes a wind turbine pitch angle dynamic compensation module, a signal processing filter module, a small signal sensitivity module, an equivalent inertia module and a wind turbine motor side speed closed-loop control module, which are sequentially connected in series with the primary frequency modulation control module; The wind turbine pitch angle dynamic compensation module is used to quickly adjust the pitch angle response and compensate for the active output changes caused by disturbances; The signal processing filter module is used to suppress high-frequency noise and smooth the control signal; The small signal sensitivity module is used to quantify the response of the wind turbine output power to small changes in the pitch angle; The equivalent inertia module is used to capture the dynamic coupling relationship between the electrical side and the mechanical side of the wind turbine and simulate the response process of the unit inertia characteristics to frequency disturbances; The fan motor side speed closed-loop control module is used to adjust the system speed error and output a stable control command.

[0008] A wind turbine pitch adjustment compensation damping control method for ultra-low frequency oscillation suppression adopts the wind turbine pitch adjustment compensation damping control system for ultra-low frequency oscillation suppression. The control method includes the following steps: S1. Continuously monitor the current system frequency of the power grid and compare it with the set reference frequency to extract the power grid frequency deviation signal; S2. Dynamically regulate the active output power of the doubly-fed wind turbine through an additional damping controller to suppress ultra-low frequency oscillations in the 0.05-0.1 Hz frequency band of the power system; S3. Construct a system frequency response model of the dynamic coupling relationship between the active power of the doubly fed wind turbine and the system frequency; adjust the parameters of the additional damping controller based on the stability analysis of the system frequency response model to optimize the oscillation damping suppression effect.

[0009] In S1, the original frequency signal reflecting the dynamic characteristics of the power grid is obtained f , the original frequency signal is input into the wind power system frequency signal extraction and filtering module, with the transfer function form of 1 / (1+ T 1s) first-order low-pass filter to filter the original frequency signal to obtain the processed signal after removing high-frequency interference f m , the processed signal f m With frequency reference value f ref Perform differential operation to obtain the grid frequency deviation signal.

[0010] The response relationship of the wind turbine output mechanical torque under grid frequency disturbance is: ; Where: Indicates the fan output mechanical torque; Indicates grid frequency deviation; represents the Laplace transform operator; Indicates the pitch angle compensation proportional gain; Indicates the pitch angle compensation integral gain; Indicates the speed loop proportional gain; Indicates the speed loop integral gain; Indicates the frequency measurement filter time constant; Indicates the pitch angle control filter time constant; Indicates the fan inertia; Indicates rated speed; Indicates the fan primary frequency modulation coefficient; represents the transfer function of the additional damping controller; Indicates the small signal sensitivity coefficient of the wind turbine active power to the pitch angle.

[0011] The wind turbine pitch adjustment compensation damping control method for ultra-low frequency oscillation suppression according to claim 3 is characterized in that, in S2, the mathematical expression of the additional damping controller is: ; Where: K p represents the damping control amplification gain; sT w / (1+ sT w ) represents the gain adjustment parameter; (1+ sT 1) m / (1+ sT 2) m represents the phase compensation parameter; When the system frequency does not change, the additional damping controller is in a non-operating state; when the system frequency changes, the additional damping controller is in an operating state.

[0012] In S2, the grid frequency monitoring and low-pass filtering module monitors the grid frequency signal in real time, obtains the dynamic frequency information under the system operation state, and adopts the first-order filtering form through the low-pass filter structure. 1 / （1+T 1 s） , filter out high-frequency disturbances; The additional damping controller gain adjustment module uses the gain coefficient K p , to control the amplitude intensity of the additional damping controller's response to frequency disturbances; The isolated DC module isolates the DC component in the frequency signal and extracts the dynamic disturbance component; The frequency control signal phase compensation module structure is (1+ sT 1) m / (1+ sT 2) m , compensates for the phase lag introduced by the grid frequency monitoring and low-pass filter module and the isolated DC module, so that the damping control signal is synchronized with the actual oscillation phase of the system, thereby outputting the positive damping torque with the correct direction to suppress low-frequency oscillation. The parameters m Indicates the phase compensation level.

[0013] The angle compensated by the frequency control signal phase compensation module comes from the transfer function of the three links of frequency monitoring, filtering and DC isolation in the grid frequency monitoring and low-pass filtering module and the isolated DC module. λi The phase shift generated at the oscillation frequency is given by: ; ; Where: is the lag time constant; is the leading time constant; is the angular frequency of the model to be adjusted; is the desired phase compensation angle.

[0014] In S3, based on the power frequency response relationship between the wind turbine and hydropower unit nodes and the power balance constraint of the system, a system frequency response model of the dynamic coupling relationship between the active power of the doubly fed wind turbine and the system frequency is constructed; The system frequency response model includes a water / fire synchronous unit speed regulator modeling unit, a water / fire synchronous unit equivalent inertia unit, and a control instruction execution and drive unit. The water / fire synchronous unit speed regulator modeling unit, the water / fire synchronous unit equivalent inertia unit, and the control instruction execution and drive unit are in parallel. The wind turbine primary frequency regulation control module and the wind power system frequency signal extraction and filtering module are connected in series with the control instruction execution and drive unit. The additional damping controller (107) is connected in parallel with the wind turbine primary frequency regulation control module. The water / fire synchronous unit speed regulator modeling unit takes the grid frequency deviation signal as input and outputs the active power reference value under speed regulation control. The equivalent inertia unit of a water / thermal synchronous unit represents the aggregated moment of inertia of a conventional water / thermal unit; The wind turbine primary frequency regulation control module is used to describe the dynamic process of the wind turbine participating in the primary frequency regulation based on the frequency deviation, converting the frequency error signal into an active power regulation instruction executable by the wind turbine, and providing basic frequency support capabilities for the wind power system; The additional damping controller is used to provide an additional damping power adjustment signal with phase compensation capability when low-frequency oscillation occurs in the system, so as to achieve a negative phase response of power disturbance to frequency disturbance near the low-frequency oscillation frequency band, so that the equivalent transfer function of the wind turbine to frequency change presents a positive damping characteristic; The control instruction execution and drive unit is used to convert the active power adjustment signal output by the additional damping controller and the wind turbine primary frequency control module into a control command recognizable by the wind turbine execution unit, and execute the target power instruction into the wind turbine output.

[0015] When constructing the system frequency response model, relevant parameter information is obtained through the modeling parameter processing unit; the modeling parameter processing unit includes a new energy station operation information collection and aggregation module, a regional hydro-generator unit quantity statistics module, an inertia parameter management module for each regional power generation unit, a turbine speed control system selection and parameter configuration module, a wind turbine linearization modeling and small signal characteristic extraction module, and a unified per-unit normalization processing module for wind power and hydropower models; The new energy station operation information collection and aggregation module centrally collects and organizes the operation data of wind power and photovoltaic new energy stations in the region. The collected content includes the online status of the unit, active power output, unit capacity, and the start and stop status of the primary frequency regulation function; The regional hydro-turbine generator unit quantity statistics module summarizes the number, capacity and distribution of traditional hydro-power units in the frequency regulation resources, including the number of hydro-turbine units, single unit capacity, access location and key information of turbine types; The inertia parameter management module for each power generation unit in the region is used to establish an inertia parameter database for wind turbines and hydropower units. For wind turbines, the inertia parameters are provided by the unit manufacturer and determined by the control loop transfer function; for hydropower and traditional units, the inertia constants are given by the factory; The turbine speed control system selection and parameter configuration module is used to match the speed regulator model type for each hydropower unit in the area and configure the corresponding control parameters; The wind turbine linearization modeling and small signal characteristics extraction module is used to perform linear modeling processing on the control logic of the wind power system, extract the equivalent small signal transfer function between the wind turbine power and frequency through the small disturbance analysis method, and determine the amplitude gain and phase characteristics of the equivalent small signal at different frequencies; The unified per-unit normalization processing module for wind power and hydropower models is used to perform per-unit normalization processing on hydropower units based on the rated capacity and frequency of the system wind turbine units, so that the rated capacity and frequency of the system wind turbine units can be integrated into a unified frequency response framework.

[0016] The beneficial effects of the present invention are: The application is parallel damping controller at the primary frequency modulation of the fan, to suppress the frequency oscillation behavior of the water and wind combined system. Compared with the conventional water turbine side additional control to suppress frequency oscillation, the scheme has two advantages: the response speed of the regulating mechanism of the fan is faster than that of the guide vane of the water turbine, the power release is more rapid at the initial stage of oscillation, and the oscillation recovery time can be effectively shortened; unlike the water hammer characteristics of the water turbine, the fan power regulation does not have the problem of reverse peak regulation at the initial response. The fan participates in the primary frequency modulation mainly by adjusting the pitch to reduce the load and reserve standby power. The main implementation idea of the application is to add a parallel pitch angle compensation control path on the basis of the traditional primary frequency modulation control, to change the active power output by dynamic pitch adjustment, to have a larger controllable power capacity for adjustment than the standby power scheme, and to have a better suppression effect on the ultra-low frequency oscillation. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0018] Figure 1 The structure block diagram of the control system of the present application.

[0019] Figure 2 The compensation control principle block diagram of the control system of the present application.

[0020] Figure 3 The frequency optimization control strategy structure block diagram of the control method of the present application.

[0021] Figure 4 The processing flow block diagram of the modeling parameter processing unit of the present application.

[0022] Figure 5 The comparison curve of the change of system frequency in the dynamic process when the double-fed fan pitch compensation damping control with designed parameters is added and when the damping control is not added.

[0023] REFERENCE NUMERALS The primary frequency modulation control module 101 of the wind turbine, the pitch angle dynamic compensation module 102 of the wind turbine, the signal processing filter module 103, the small signal sensitivity module 104, the equivalent inertia module 105, the motor side speed closed loop control module 106 of the fan, the additional damping controller 107, the wind power system frequency signal extraction and filtering module 108; The grid frequency monitoring and low pass filtering module 201, the additional damping controller gain adjustment module 202, the isolation DC module 203, the frequency control signal phase compensation module 204; Water / thermal synchronous unit governor modeling unit 301, water / thermal synchronous unit equivalent inertia unit 302, control instruction execution and driving unit 303 New energy field station operation information acquisition and summary module 401, regional water turbine generator set quantity statistical module 402, regional each power generation unit inertia parameter management module 403, water turbine speed regulation system selection and parameter configuration module 404, wind turbine linear modeling and small signal characteristic extraction module 405, wind power and water power model unified scaling processing module 406. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0025] Referring to Figure 1 As shown in the figure, a wind turbine pitch compensation damping control system for ultra-low frequency oscillation suppression includes a wind turbine primary frequency control module 101, and further includes an additional damping controller 107 connected in parallel with the wind turbine primary frequency control module 101 and then connected into a pitch angle compensation control system.

[0026] By connecting the additional damping controller 107 in parallel on the wind turbine side, the grid ultra-low frequency oscillation is suppressed through pitch angle control adjustment. The key for the wind turbine to participate in regulating the grid frequency is to build a dynamic feedback regulation mechanism between the wind turbine output power and the system frequency variation on the basis of reserving certain load shedding capacity. After reserving the load shedding capacity, the wind turbine operates on a suboptimal power curve. When the system frequency fluctuates, the primary frequency control and the additional damping controller 107 operate in parallel to take the deviation between the real-time measured frequency value and the frequency instruction value as an input quantity, change the pitch angle compensation instruction value, and then adjust the actual output value of the pitch angle control, so as to finally realize the adjustment of the wind turbine output mechanical power.

[0027] In the embodiment, referring to Figure 2 The additional damping controller 107 includes, in sequence, a grid frequency monitoring and low-pass filtering module 201, an additional damping controller gain adjustment module 202, an isolation DC module 203, and a frequency control signal phase compensation module 204. The grid frequency monitoring and low-pass filtering module 201 is used for frequency monitoring and low-pass filtering, the additional damping controller gain adjustment module 202 is used for gain adjustment, the isolation DC module 203 is used for isolation of DC components, and the frequency control signal phase compensation module 204 is used for frequency control signal phase compensation.

[0028] Specifically, the grid frequency monitoring and low-pass filtering module 201 is used to monitor the grid frequency signal f Real-time monitoring is performed to obtain dynamic frequency information under the system operation state. In order to improve the signal quality, the module is designed with a low-pass filter structure to filter out high-frequency disturbances. First-order filtering is often used. 1 / （1+T 1 s） Through this filter, the main low-frequency dynamic changes of the frequency are extracted, providing high-reliability input for the subsequent execution of damping control.

[0029] The core of the additional damping controller gain adjustment module 202 is the proportional gain coefficient K p , which determines the amplitude strength of the controller's response to frequency disturbances. In the doubly fed wind turbine damping control strategy, the parameter K p It directly determines the intensity of the additional damping injection of the system and directly affects the suppression effect of low-frequency oscillation. K p The value can help improve the damping performance, but its tuning process needs to comprehensively consider multiple constraints such as system stability, fan control margin and response speed to ensure that the controller avoids introducing new unstable factors while improving the dynamic performance.

[0030] The isolated DC module 203 adopts a low-pass filter structure for compensation. sT w / (1+ sT w ), whose main function is to isolate the DC component in the frequency signal and extract only the dynamic disturbance component. This link setting can prevent the additional controller from responding to the steady-state frequency deviation, thereby avoiding interference with the primary frequency modulation control. Filter time constant T w The selection needs to ensure sufficient attenuation capability for DC signals, while avoiding the ultra-low frequency oscillation band of the power system to prevent resonance.

[0031] The frequency control signal phase compensation module 204 is used to perform phase correction on the control signal to ensure that the damping controller provides an effective positive damping response in the key oscillation frequency band of the system. Its structure is (1+ sT 1) m / (1+ sT 2) m Through this compensation link, the phase lag introduced by the frequency measurement, low-pass filtering and DC isolation links is compensated, so that the damping control signal is synchronized with the actual oscillation phase of the system, thereby outputting a positive damping torque with the correct direction to suppress low-frequency oscillation. mRepresents the number of phase compensation stages. This number is positively correlated with the angle to be compensated. That is, the larger the angle to be compensated, the more stages are required. Typically, each compensation angle does not exceed 60°. ω i is the angular frequency of the model to be adjusted. For the ultra-low frequency oscillation mode, the angular frequency can be selected as 0.05×2π= 0.3142rad. The angle compensated by the compensation link is derived from the transfer function of the three links of frequency measurement, filtering, and DC isolation in the front. λi The phase shift produced at the oscillation frequency.

[0032] Furthermore, the pitch angle compensation control structure also includes a wind turbine pitch angle dynamic compensation module 102, a signal processing filter module 103, a small signal sensitivity module 104, an equivalent inertia module 105 and a wind turbine motor side speed closed-loop control module 106, which are sequentially connected in series with the primary frequency modulation control module 101.

[0033] Specifically, in the frequency control process, the additional power signal generated is passed through the wind turbine pitch angle dynamic compensation module 102 using a proportional-integral structure. k pc +k ic / s , where the proportional term is used to improve the system response speed, and the integral term is used to eliminate steady-state errors. The wind turbine pitch angle dynamic compensation module 102 is mainly used to quickly adjust the pitch angle response and compensate for the active output changes caused by disturbances.

[0034] The control signal after pitch angle compensation is further input into the signal processing filter module 103 for filtering. The module adopts a first-order low-pass filter structure, and its transfer function is: 1 / (T p s+1) , which suppresses high-frequency noise, smoothes control signals, and improves the stability and anti-interference ability of the control link.

[0035] The filtered signal will be linearly calculated with the small signal sensitivity coefficient of the wind turbine active power to the pitch angle provided by the small signal sensitivity module 104. This coefficient is defined as P m / β , used to quantify the output power of wind turbines P m Pitch angle β Specifically, by multiplying the control signal with the sensitivity coefficient, the relationship between pitch control and grid frequency response is established.

[0036] The active regulation signal is further input into the dual mass system inertia model established by the equivalent inertia module 105 for processing.1 / 2Hω r0 s ,in H is the equivalent inertia constant, ω r0 The model can effectively capture the dynamic coupling relationship between the electrical and mechanical sides of the wind turbine, accurately simulate the response of the unit's inertia characteristics to frequency disturbances, and reflect the ability of the wind turbine to participate in inertial support.

[0037] The processed signal is finally transmitted to the wind turbine motor side speed closed-loop control module 106, that is, the speed closed-loop controller of the wind turbine group. The controller also adopts the proportional-integral structure, and the expression is k pw +k iw / s , used to adjust the system speed error and output a stable control command. After the above series of dynamic compensation, filtering and control processing, the system generates a target torque reference value T ref .

[0038] Example 2: Based on Example 1, a wind turbine pitch adjustment compensation damping control method for ultra-low frequency oscillation suppression adopts a wind turbine pitch adjustment compensation damping control system for ultra-low frequency oscillation suppression. The control method includes the following steps: S1. Continuously monitor the current system frequency of the power grid and compare it with the set reference frequency to extract the power grid frequency deviation signal; S2. Dynamically regulating the active output power of the doubly-fed wind turbine through the additional damping controller 107 to suppress ultra-low frequency oscillations in the 0.05-0.1 Hz frequency band of the power system; S3. Construct a system frequency response model of the dynamic coupling relationship between the active power of the doubly fed wind turbine and the system frequency; adjust the parameters of the additional damping controller 107 based on the stability analysis of the system frequency response model to optimize the oscillation damping suppression effect.

[0039] The present invention introduces an additional damping controller 107 in parallel with the conventional primary frequency modulation control input and output ports, and changes the power output active power through dynamic pitch adjustment to enhance the dynamic response capability and damping characteristics of the wind power system under frequency disturbances, so as to suppress the ultra-low frequency oscillation in the 0.05-0.1Hz frequency band of the power system.

[0040] In S1, see Figure 1 First, the signal processing device is based on the system frequency fReal-time detection is performed to obtain the original frequency signal reflecting the dynamic characteristics of the power grid. In order to improve the stability and availability of the signal, the signal is input to the wind power system frequency signal extraction and filtering module 108, in the form of a transfer function 1 / （1+T 1 s） The first-order low-pass filter is used to filter the original signal to obtain the processed signal after removing high-frequency interference. f m , the processed signal f m With frequency reference value f ref Perform differential operation to obtain the grid frequency deviation signal.

[0041] Among them, the response relationship of the wind turbine output mechanical torque under grid frequency disturbance is: ; Where: Indicates the fan output mechanical torque; Indicates grid frequency deviation; represents the Laplace transform operator; Indicates the pitch angle compensation proportional gain; Indicates the pitch angle compensation integral gain; Indicates the speed loop proportional gain; Indicates the speed loop integral gain; Indicates the frequency measurement filter time constant; Indicates the pitch angle control filter time constant; Indicates the fan inertia; Indicates rated speed; Indicates the fan primary frequency modulation coefficient; represents the transfer function of the additional damping controller; Indicates the small signal sensitivity coefficient of the wind turbine active power to the pitch angle.

[0042] In S2, the mathematical expression of the additional damping controller 107 is: ; Where: K p represents the proportional gain coefficient; sT w / (1+ sT w ) represents the gain adjustment parameter; (1+ sT 1) m / (1+ sT 2) m represents the phase compensation parameter; The additional damping controller 107 is in a non-working state when the system frequency does not change, and is in a working state when the system frequency changes.

[0043] In S2, the power grid frequency monitoring and low-pass filtering module 201 monitors the power grid frequency signal in real time, obtains dynamic frequency information in the system running state, and filters high-frequency disturbances through a low-pass filter structure. A first-order filter form is adopted . Through the power grid frequency monitoring and low-pass filtering module 201, the main low-frequency dynamic change of the frequency is extracted, providing a highly reliable input for the subsequent execution of the damping control.

[0044] The additional damping controller gain adjustment module 202, the core of which is the proportional gain coefficient K p , determines the amplitude strength of the controller response to frequency disturbances. In the damping control strategy of the doubly-fed wind turbine, the parameter K p directly determines the strength of the additional damping injection of the system and directly affects the suppression effect of low-frequency oscillation. Although a larger K p value helps to improve the damping performance, the setting process needs to consider multiple constraints such as system stability, wind turbine control margin and response speed, to ensure that the controller improves the dynamic performance while avoiding the introduction of new unstable factors.

[0045] The isolation DC module 203 adopts a compensation form of a low-pass filter structure , and its main function is to isolate the DC component in the frequency signal and extract only the dynamic disturbance component. The setting of this link can prevent the additional controller from responding to the steady-state frequency deviation, thereby avoiding interference with the primary frequency control. The selection of the filter time constant T w needs to ensure sufficient attenuation capability for the DC signal, while avoiding the super-low frequency oscillation frequency band of the power system to prevent resonance.

[0046] The frequency control signal phase compensation module 204 is used for phase correction of the control signal, to ensure that the damping controller provides effective positive damping response in the key oscillation frequency band of the system. The structure is , through this compensation link, the phase lag introduced by the frequency measurement, low-pass filtering and DC isolation pre-link is compensated, so that the damping control signal and the actual oscillation phase of the system are kept in synchronization, thereby outputting a positive damping torque in the correct direction to suppress low-frequency oscillation. The parameter m represents the number of phase compensation stages, which needs to be positively related to the compensation stage according to the angle to be compensated. That is, the greater the compensation angle, the more the compensation stages. Usually, the compensation angle of each stage does not exceed 60°. ωi is the angular frequency of the model to be adjusted. For the ultra-low frequency oscillation mode, the angular frequency can be selected as 0.05×2π= 0.3142rad.

[0047] The angle compensated by the frequency control signal phase compensation module 204 is derived from the transfer functions of the three links of frequency monitoring, filtering and DC isolation in the grid frequency monitoring and low-pass filtering module 201 and the DC isolation module 203. λi The phase shift generated at the oscillation frequency is given by: ; ; Where: is the lag time constant; is the leading time constant; is the angular frequency of the model to be adjusted; is the desired phase compensation angle.

[0048] By drawing the Bode diagram, we can see that at the 0.05Hz frequency point, the frequency monitoring, filtering, and DC isolation links cause a phase shift of -115°. Therefore, the phase compensation link needs to generate a 115° leading phase to ensure that it can point horizontally to the right half plane in the frequency response mode, thereby providing positive damping. According to the relevant formula, the compensation level can be selected m =4, and calculate separately T 1=5.0012s, T 2=1.96664s.

[0049] The above steps determine the basic architecture and functional units of the compensation controller, but its effectiveness in suppressing ultra-low frequency oscillations depends on the reasonable setting of control parameters. It is necessary to build a system frequency response mathematical model that can accurately reflect the dynamic coupling relationship between the active power of the doubly fed wind turbine and the system frequency, so as to conduct quantitative analysis of the ultra-low frequency oscillation under the closed-loop stability of the system and thus guide parameter design. The specific system mathematical model modeling ideas are as follows: In the dynamic analysis of power systems, a system consisting of n synchronous generators is considered. When power imbalance occurs, the internal potential frequency dynamics of each generator can be described by the rotor motion equation: ; Where: Δ P mSM_i For the i Input mechanical power of synchronous generators, Δ P lSM_i For the i The electromagnetic power output of a synchronous generator, Δω i is the frequency deviation value of the i-th synchronous machine, H SM_iFor the i The inertia of the synchronous machine.

[0050] Since ultra-low frequency oscillation is a global coherent oscillation problem of the system, it can be considered that all nodes have the same frequency. is the weighted average frequency of all devices. The system input power can be simplified to the following approximate expression: ; In traditional synchronous generator systems, the inertia of a single unit and the total inertia of the system are kept constant, and their frequency response characteristics are mainly determined by the power imbalance and the dynamic characteristics of the speed regulator. Doubly fed wind turbines exhibit time-varying inertia characteristics and need to be characterized by dynamic transfer functions. This difference makes the system frequency dynamic process not only affected by conventional regulation characteristics, but also related to the inertia change characteristics of the unit. By using the small signal linearization method to process the doubly fed wind turbine model, the following can be obtained: Figure 1 The equivalent inertia and frequency regulation transfer function expressions are shown in Figure 2. Based on the superposition principle, the dynamic characteristics of new energy units and traditional synchronous machines are integrated to establish a frequency dynamic analysis model suitable for high-proportion new energy power systems.

[0051] After linearization of the doubly-fed wind turbine, a transfer function block diagram model can be established with power disturbance as input and power angle change as output. Using a derivation method similar to the synchronous generator frequency response model, we now consider a hybrid power generation system consisting of m synchronous generators and n doubly-fed wind turbines. In the dynamic characteristics analysis of the doubly-fed induction generator (DFIG), by equivalently converting the input mechanical power, its internal potential and speed dynamics can be represented by the following mathematical expression: ; When the line impedance loss is ignored, the grid power balance relationship can be obtained as follows: ; In summary, based on the power frequency response relationship between the wind turbine and hydropower unit nodes and the power balance constraint of the system, a system frequency response model of the dynamic coupling relationship between the active power of the doubly fed wind turbine and the system frequency is constructed.

[0052] See also Figure 3 The system frequency response model includes a water / fire synchronous unit speed regulator modeling unit 301, a water / fire synchronous unit equivalent inertia unit 302, a wind turbine primary frequency regulation control module 101, a wind power system frequency signal extraction and filtering module 108, a control instruction execution and drive unit 303, and an additional damping controller 107.

[0053] The water / thermal synchronous unit governor modeling unit 301, the water / thermal synchronous unit equivalent inertia unit 302, and the control instruction execution and driving unit 303 are in parallel relationship, the wind turbine primary frequency modulation control module 101 and the wind power system frequency signal extraction and filtering module 108 are in series with the control instruction execution and driving unit 303, and the additional damping controller 107 is in parallel with the wind turbine primary frequency modulation control module 101; The water / thermal synchronous unit governor modeling unit 301 is used to establish a dynamic model of a speed regulation system when the wind turbine and the water / thermal turbine jointly participate in system frequency control. The joint governor model takes a frequency deviation signal as input and outputs an active power reference value, realizing the control logic of the coordinated response of the two types of units to frequency disturbance.

[0054] The water / thermal synchronous unit equivalent inertia unit 302 is used to integrate the inertia characteristics of the wind power and the water / thermal power two types of units, forming a unified equivalent inertia model. The wind power system inertia mainly depends on the unit rotational inertia and the controller response rate, and the water / thermal power system inertia is usually a factory reference value.

[0055] The wind turbine primary frequency modulation control module 101 is used to describe the dynamic process of the wind turbine participating in primary frequency modulation based on frequency deviation. The core control structure includes a primary frequency modulation proportional gain K f , a filtering device 1 / (1+ T 1s). This link converts the frequency error signal into an active power regulation instruction executable by the wind turbine, providing basic frequency support capability for the wind power system. Its output constitutes the main active support path of the wind turbine in the steady-state frequency control process.

[0056] The additional damping controller 107 is used to provide an additional damping power regulation signal with phase compensation capability when system low-frequency oscillation occurs. Its goal is to realize the negative phase response of power disturbance to frequency disturbance near the low-frequency oscillation frequency band, so that the equivalent transfer function of the wind turbine to frequency change presents a positive damping characteristic, thereby enhancing the suppression ability of the system to the oscillation mode.

[0057] The control instruction execution and driving unit 303 is responsible for converting the active power regulation signals output by the additional damping controller 107 and the wind turbine primary frequency modulation control module 101 into control commands recognizable by the wind turbine execution unit. The target power instruction P ref is executed into the wind turbine output. Ensure that the control strategy is stable and efficient under the equipment constraint condition.

[0058] When building the system frequency response model, the relevant parameter information is obtained through the modeling parameter processing unit.

[0059] Referring to Figure 4The modeling parameter processing unit includes a new energy station operation information collection and aggregation module 401, a regional hydropower generator unit quantity statistics module 402, an inertia parameter management module for each regional power generation unit 403, a turbine speed control system selection and parameter configuration module 404, a wind turbine linearization modeling and small signal characteristic extraction module 405, and a wind power and hydropower model unified standardization processing module 406.

[0060] The new energy station operation information collection and aggregation module 401 is used to centrally collect and organize operational data from regional wind power, photovoltaic, and other new energy stations. This information includes unit online status, active power output, unit capacity, and the start and stop status of the primary frequency regulation function. This standardizes and centralizes operational characteristic data for new energy resources, providing foundational support for subsequent frequency response modeling.

[0061] Regional hydroelectric generator unit statistics module 402 aggregates the number, capacity, and distribution of traditional hydroelectric units within frequency regulation resources. This module typically includes key information such as the number of hydroelectric units, unit capacity, connection location, and turbine type (e.g., Francis or Axial), facilitating subsequent speed regulation model selection and inertia parameter estimation.

[0062] The regional power generation unit inertia parameter management module 403 is used to establish an inertia parameter database for wind turbines and hydropower units. For wind turbines, inertia parameters can be provided by the unit manufacturer and determined by the control loop transfer function. For hydropower and traditional units, the inertia constant is typically given at the factory, laying the foundation for subsequent unified inertia modeling and frequency dynamic response calculations.

[0063] The turbine speed control system selection and parameter configuration module 404 is used to match the speed control model type, such as a conventional PID speed control system or an electro-hydraulic speed control system, to each hydropower unit in the region and configure the corresponding control parameters. Proper selection and configuration of speed control system parameters is crucial for dynamic response characteristics under frequency disturbances and directly impacts the accuracy of the frequency response model.

[0064] The wind turbine linearization modeling and small signal characteristic extraction module 405 is one of the core steps in building the frequency response model. It performs linear modeling on the control logic of the wind power system (such as speed controller, MPPT control, primary frequency controller, additional damping link, etc.). The equivalent small signal transfer function between the wind turbine power and frequency is extracted through the small disturbance analysis method. G(s) , determine its amplitude gain and phase characteristics at different frequencies.

[0065] Because different types of power generation units have different power levels, parameter dimensions, and response scales, all sub-models must be uniformly normalized to ensure the universality and comparability of the frequency response model. Wind and hydropower model unified normalization module 406 normalizes the hydropower units based on the rated capacity and frequency of the system's wind turbines, enabling their integration into a unified frequency response framework. This normalized model facilitates frequency response calculations, system simulations, and stability analysis, and provides a benchmark for subsequent damping optimization, controller tuning, and other processes.

[0066] By linearizing the frequency response closed-loop model transfer, the influence of different parameters such as compensation controller gain and phase compensation can be analyzed and confirmed based on the root locus, and the reasonable selection range of parameters can be determined.

[0067] Figure 5 The curves of the system frequency change during the dynamic process are shown in Figure 2. The actual application is not limited to the above structures and parameters. The simulation adopts an improved two-machine system, in which one synchronous unit is replaced by a wind farm of the same capacity with primary frequency regulation control, and 30 is added at 100s. MW Active power disturbance load, the optimized control gain is obtained through the above process K p When it is 60, the oscillation amplitude of the system at the ultra-low frequency oscillation of 0.05Hz is significantly reduced, which can effectively improve the damping of the system in the ultra-low frequency band.

[0068] In summary, the present invention improves system frequency stability by providing an additional damping controller 107 in parallel with the primary frequency modulation control of the wind turbine and calculating control parameters. This controller monitors the frequency deviation signal in real time and adds it to the pitch angle control. By adjusting the active power actually output by the wind turbine, it provides positive damping for the system during ultra-low frequency oscillations, thereby suppressing system oscillations. This compensatory control does not affect the regulation of the system's steady-state frequency, complementing traditional primary frequency modulation control. This controller has promising engineering applications in the field of power system stability control.

[0069] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined in this specification, they should all fall within the scope of protection of the present invention.

Claims

1. A wind turbine pitch control compensation damping control system for ultra-low frequency oscillation suppression, comprising a wind turbine primary frequency modulation control module (101), characterized in that: It also includes an additional damping controller (107), which is connected in parallel with the primary frequency modulation control module (101) of the wind turbine generator set and then connected to the pitch angle compensation control system; The additional damping controller (107) comprises a power grid frequency monitoring and low-pass filtering module (201), an additional damping controller gain adjustment module (202), an isolated DC module (203), and a frequency control signal phase compensation module (204) which are sequentially connected in series. The power grid frequency monitoring and low-pass filtering module (201) is used for frequency monitoring and low-pass filtering, the additional damping controller gain adjustment module (202) is used for gain adjustment, the isolated DC module (203) is used for isolating DC components, and the frequency control signal phase compensation module (204) is used for frequency control signal phase compensation.

2. The wind turbine pitch adjustment compensation damping control system for ultra-low frequency oscillation suppression according to claim 1, characterized in that: The pitch angle compensation control system comprises a wind turbine pitch angle dynamic compensation module (102), a signal processing filter module (103), a small signal sensitivity module (104), an equivalent inertia module (105), and a wind turbine motor side speed closed-loop control module (106), which are sequentially connected in series with the primary frequency modulation control module (101); The wind turbine pitch angle dynamic compensation module (102) is used to quickly adjust the pitch angle response and compensate for the active power output change caused by disturbance; The signal processing filter module (103) is used to suppress high-frequency noise and smooth the control signal; The small signal sensitivity module (104) is used to quantify the response of the wind turbine output power to a small change in the pitch angle; The equivalent inertia module (105) is used to capture the dynamic coupling relationship between the electrical side and the mechanical side of the fan, and simulate the response process of the unit inertia characteristics to the frequency disturbance; The fan motor side speed closed-loop control module (106) is used to adjust the system speed error and output a stable control command.

3. A wind turbine pitch compensation damping control method for ultra-low frequency oscillation suppression, characterized in that: A wind turbine pitch compensation damping control system for ultra-low frequency oscillation suppression according to claim 1 or 2 is adopted, and the control method includes the following steps: S1. Continuously monitor the current system frequency of the power grid and compare it with the set reference frequency to extract the power grid frequency deviation signal; S2, dynamically regulating the active output power of the doubly-fed wind turbine through an additional damping controller (107) to suppress ultra-low frequency oscillations in the 0.05-0.1 Hz frequency band of the power system; S3. Construct a system frequency response model of the dynamic coupling relationship between the active power of the doubly fed wind turbine and the system frequency; adjust the parameters of the additional damping controller (107) based on the stability analysis of the system frequency response model to optimize the oscillation damping suppression effect.

4. The wind turbine pitch adjustment compensation damping control method for ultra-low frequency oscillation suppression according to claim 3, characterized in that: In S1, the original frequency signal reflecting the dynamic characteristics of the power grid is obtained f , the original frequency signal is input into the wind power system frequency signal extraction and filtering module (108), with the transfer function form of 1 / (1+ T 1s) first-order low-pass filter to filter the original frequency signal to obtain the processed signal after removing high-frequency interference f m , the processed signal f m With frequency reference value f ref Perform differential operation to obtain the grid frequency deviation signal.

5. The wind turbine pitch adjustment compensation damping control method for ultra-low frequency oscillation suppression according to claim 4, characterized in that: The response relationship of the wind turbine output mechanical torque under grid frequency disturbance is: ； Where: Indicates the fan output mechanical torque; Indicates grid frequency deviation; represents the Laplace transform operator; Indicates the pitch angle compensation proportional gain; Indicates the pitch angle compensation integral gain; Indicates the speed loop proportional gain; Indicates the speed loop integral gain; Indicates the frequency measurement filter time constant; Indicates the pitch angle control filter time constant; Indicates the fan inertia; Indicates rated speed; Indicates the fan primary frequency modulation coefficient; represents the transfer function of the additional damping controller; Indicates the small signal sensitivity coefficient of the wind turbine active power to the pitch angle.

6. The wind turbine pitch adjustment compensation damping control method for ultra-low frequency oscillation suppression according to claim 3, characterized in that: In S2, the mathematical expression of the additional damping controller (107) is: ； Where: K p represents the damping control amplification gain; sT w / (1+ sT w ) represents the DC isolation link; (1+ sT 1) m / (1+ sT 2) m represents the phase compensation parameter; When the system frequency does not change, the additional damping controller (107) is in a non-operating state, and when the system frequency changes, the additional damping controller (107) is in an operating state.

7. The wind turbine pitch adjustment compensation damping control method for ultra-low frequency oscillation suppression according to claim 6, characterized in that: In S2, the grid frequency monitoring and low-pass filtering module (201) monitors the grid frequency signal in real time, obtains dynamic frequency information under the system operation state, and filters out high-frequency disturbances through a low-pass filter structure and a first-order filtering form; The additional damping controller gain adjustment module (202) is adjusted by the gain coefficient K p , to control the amplitude intensity of the additional damping controller (107) response to the frequency disturbance; The isolated DC module (203) isolates the DC component in the frequency signal and extracts the dynamic disturbance component; The frequency control signal phase compensation module (204) has a structure of (1+ sT 1) m / (1+ sT 2) m , the phase lag introduced by the grid frequency monitoring and low-pass filtering module (201) and the isolated DC module (203) is compensated so that the damping control signal is synchronized with the actual oscillation phase of the system, thereby outputting a positive damping torque with the correct direction to suppress low-frequency oscillation. The parameters m Indicates the phase compensation level.

8. The wind turbine pitch adjustment compensation damping control method for ultra-low frequency oscillation suppression according to claim 7, characterized in that: The angle compensated by the frequency control signal phase compensation module (204) is derived from the transfer functions of the three links of frequency monitoring, filtering and DC isolation in the grid frequency monitoring and low-pass filtering module (201) and the DC isolation module (203). λ i The phase shift generated at the oscillation frequency is given by: ； ； Where: is the lag time constant; is the leading time constant; is the angular frequency of the model to be adjusted; is the desired phase compensation angle.

9. The wind turbine pitch adjustment compensation damping control method for ultra-low frequency oscillation suppression according to claim 3, characterized in that: In S3, based on the power frequency response relationship between the wind turbine and hydropower unit nodes and the power balance constraint of the system, a system frequency response model of the dynamic coupling relationship between the active power of the doubly fed wind turbine and the system frequency is constructed; The system frequency response model includes a water / fire synchronous unit speed regulator modeling unit (301), a water / fire synchronous unit equivalent inertia unit (302), and a control instruction execution and drive unit (303), wherein the water / fire synchronous unit speed regulator modeling unit (301), the water / fire synchronous unit equivalent inertia unit (302), and the control instruction execution and drive unit (303) are in a parallel relationship, a wind turbine primary frequency regulation control module (101) and a wind power system frequency signal extraction and filtering module (108) are connected in series with the control instruction execution and drive unit (303), and an additional damping controller (107) is connected in parallel with the wind turbine primary frequency regulation control module (101); The water / fire synchronous unit speed regulator modeling unit (301) takes the grid frequency deviation signal as input and outputs the active power reference value under speed regulation control. The equivalent inertia unit (302) of the water / thermal synchronous unit represents the aggregated rotational inertia of the traditional water / thermal power unit; The wind turbine primary frequency regulation control module (101) is used to describe the dynamic process of the wind turbine participating in the primary frequency regulation based on the frequency deviation, convert the frequency error signal into an active power regulation instruction executable by the wind turbine, and provide basic frequency support capability for the wind power system; The additional damping controller (107) is used to provide an additional damping power adjustment signal with phase compensation capability when low-frequency oscillation of the system occurs, so as to achieve a negative phase response of power disturbance to frequency disturbance near the low-frequency oscillation frequency band, so that the equivalent transfer function of the wind turbine to frequency change presents a positive damping characteristic; The control instruction execution and drive unit (303) is used to convert the active power regulation signal output by the additional damping controller (107) and the wind turbine primary frequency regulation control module (101) into a control command recognizable by the wind turbine execution unit, and execute the target power instruction into the wind turbine output.

10. The wind turbine pitch adjustment compensation damping control method for ultra-low frequency oscillation suppression according to claim 9, characterized in that: When constructing a system frequency response model, relevant parameter information is obtained through a modeling parameter processing unit; the modeling parameter processing unit includes a new energy station operation information collection and aggregation module (401), a regional hydro-generator unit quantity statistics module (402), an inertia parameter management module for each regional power generation unit (403), a turbine speed control system selection and parameter configuration module (404), a wind turbine linearization modeling and small signal characteristic extraction module (405), and a wind power and hydropower model unified standardization processing module (406); The new energy station operation information collection and aggregation module (401) centrally collects and organizes the operation data of wind power and photovoltaic new energy stations in the region, and the collected content includes the online status of the unit, active power output, unit capacity and the start and stop status of the primary frequency regulation function; The regional hydroelectric generator unit number statistics module (402) performs statistics on the number, capacity and distribution of traditional hydroelectric units in the frequency regulation resources, and the statistics include the number of hydroelectric units, single unit capacity, access location and key information of turbine types; The inertia parameter management module (403) of each power generation unit in the region is used to establish an inertia parameter database of wind turbines and hydropower units. For wind turbines, the inertia parameters are provided by the unit manufacturer and determined by the control loop transfer function; for hydropower and traditional units, the inertia constants are given by the factory; The turbine speed control system selection and parameter configuration module (404) is used to match the speed regulator model type for each hydropower unit in the area and configure the corresponding control parameters; The wind turbine linearization modeling and small signal characteristic extraction module (405) is used to perform linearization modeling processing on the control logic of the wind power system, and extract the equivalent small signal transfer function between the wind turbine power and frequency through the small disturbance analysis method. G(s) , determine the amplitude gain and phase characteristics of the equivalent small signal at different frequencies; The wind power and hydropower model unified per-unit processing module (406) is used to perform per-unit processing on the hydropower generator set based on the rated capacity and frequency of the system wind generator set, so that the rated capacity and frequency of the system wind generator set can be integrated into a unified frequency response framework.

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