WO2023045469A1 - 电网频率检测方法和装置及电网频率调节方法和装置 - Google Patents

电网频率检测方法和装置及电网频率调节方法和装置 Download PDF

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WO2023045469A1
WO2023045469A1 PCT/CN2022/102858 CN2022102858W WO2023045469A1 WO 2023045469 A1 WO2023045469 A1 WO 2023045469A1 CN 2022102858 W CN2022102858 W CN 2022102858W WO 2023045469 A1 WO2023045469 A1 WO 2023045469A1
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grid frequency
voltage
grid
frequency
component
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PCT/CN2022/102858
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English (en)
French (fr)
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曹晓东
刘世军
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新疆金风科技股份有限公司
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Priority to KR1020247008817A priority Critical patent/KR20240050378A/ko
Priority to AU2022349378A priority patent/AU2022349378A1/en
Priority to EP22871530.6A priority patent/EP4375682A1/en
Publication of WO2023045469A1 publication Critical patent/WO2023045469A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/02—Arrangements for measuring frequency, e.g. pulse repetition rate; Arrangements for measuring period of current or voltage
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
    • G01R19/2513—Arrangements for monitoring electric power systems, e.g. power lines or loads; Logging
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R21/00—Arrangements for measuring electric power or power factor
    • G01R21/001—Measuring real or reactive component; Measuring apparent energy
    • G01R21/002—Measuring real component
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/16—Spectrum analysis; Fourier analysis
    • G01R23/165—Spectrum analysis; Fourier analysis using filters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R25/00—Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/34—Testing dynamo-electric machines
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H02J3/241—The oscillation concerning frequency
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/48—Controlling the sharing of the in-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects

Definitions

  • the present disclosure generally relates to the field of electric power technology, and more specifically, relates to a grid frequency detection method and device, and a grid frequency adjustment method and device.
  • Grid-connected wind farms need to have the functions of inertia response and primary frequency modulation.
  • Large-scale wind turbines are connected to the power grid through converters. Compared with synchronous generators in traditional power grids (such as thermal power and hydropower generators), they have the advantages of flexible control and rapid response.
  • the main ways for wind turbines to participate in inertia support and grid frequency regulation are: rotor kinetic energy control method and backup power control method.
  • the high-precision power grid frequency detection is the basis for realizing inertia response and primary frequency regulation.
  • Exemplary embodiments of the present disclosure provide a grid frequency detection method and device and a grid frequency adjustment method and device, which can detect grid frequency conveniently, quickly and accurately, and effectively adjust grid frequency.
  • a grid frequency detection method including: converting the collected three-phase voltage of the grid-connected point into a two-phase voltage; converting the two-phase voltage based on a phase angle of a specific frequency, Obtaining the voltage positive sequence component and voltage negative sequence component to be decoupled; decoupling the voltage positive sequence component and voltage negative sequence component to be decoupled based on the phase angle, and filtering the decoupled voltage positive sequence component, Obtaining the voltage positive sequence fundamental wave component; performing inverse transformation on the voltage positive sequence fundamental wave component based on the phase angle to obtain a set of orthogonal voltage components in a two-phase stationary coordinate system; based on the set of orthogonal voltage components , to obtain the grid phase angle; based on the grid phase angle, to obtain the grid frequency.
  • a grid frequency adjustment method including: determining whether there is a disturbance in the three-phase voltage amplitude of the grid-connected point; when there is no disturbance, according to the detected grid frequency and/or grid frequency change rate, determine whether the grid frequency adjustment response condition is satisfied; when the grid frequency adjustment response condition is met, control the power of the wind power generating set based on the grid frequency and/or the grid frequency change rate, so as to adjust the grid frequency;
  • the grid frequency and/or the grid frequency change rate are obtained by performing the grid frequency detection method as described above.
  • a power grid frequency detection device including: a two-phase voltage acquisition unit configured to convert the collected three-phase voltage of a grid-connected point into a two-phase voltage; the conversion unit is configured to The two-phase voltage is transformed based on the phase angle of a specific frequency to obtain a positive sequence component of the voltage to be decoupled and a negative sequence component of the voltage; a decoupling filter unit is configured as a positive sequence voltage to be decoupled based on the phase angle component and the voltage negative-sequence component are decoupled, and the decoupled voltage positive-sequence component is filtered to obtain the voltage positive-sequence fundamental wave component; the inverse transformation unit is configured to perform the voltage positive-sequence fundamental wave component based on the phase angle The wave component is inversely transformed to obtain a set of orthogonal voltage components under the two-phase stationary coordinate system; the grid phase angle acquisition unit is configured to obtain the grid phase angle based on the set of orthogonal voltage components under the two-phase stationary coordinate system; the grid phase angle
  • a power grid frequency adjustment device including: a voltage disturbance judging unit configured to determine whether there is a disturbance in the three-phase voltage amplitude of the grid-connected point; a response condition judging unit configured to When there is no disturbance, according to the detected grid frequency and/or grid frequency change rate, determine whether the grid frequency adjustment response condition is met; the grid frequency adjustment unit is configured to, when the grid frequency adjustment response condition is met, based on the grid The frequency and/or the rate of change of the grid frequency control the power of the wind power generating set to adjust the grid frequency; wherein the grid frequency and/or the rate of change of the grid frequency are obtained by the above-mentioned grid frequency detection device.
  • a computer-readable storage medium storing a computer program.
  • the processor is prompted to execute the above-mentioned power grid frequency detection method and /or the grid frequency adjustment method as described above.
  • an electronic device includes: a processor; a memory storing a computer program, when the computer program is executed by the processor, the processor is prompted to perform the above The grid frequency detection method and/or the grid frequency adjustment method described above.
  • the power grid frequency detection method and the power grid frequency adjustment method proposed in the present disclosure can be realized without adding additional hardware to the wind power generating set, so as to realize rapid development, new model application and on-site transformation;
  • the active power increment is calculated, and the active power increment is converted into the motor control torque command to complete the power control, and then realize the unit inertia response and primary frequency regulation.
  • FIG. 1 shows a flowchart of a grid frequency detection method according to an exemplary embodiment of the present disclosure
  • FIG. 2 shows an example of a grid frequency detection method according to an exemplary embodiment of the present disclosure
  • Fig. 3 shows a flowchart of a grid frequency regulation method according to an exemplary embodiment of the present disclosure
  • Fig. 4 shows a flowchart of a grid frequency regulation method according to another exemplary embodiment of the present disclosure
  • FIG. 5 shows an example of an inertia response test according to an exemplary embodiment of the present disclosure
  • Fig. 6 shows an example of a FM test according to an exemplary embodiment of the present disclosure
  • Fig. 7 shows a structural block diagram of a power grid frequency detection device according to an exemplary embodiment of the present disclosure
  • Fig. 8 shows a structural block diagram of a power grid frequency regulating device according to an exemplary embodiment of the present disclosure.
  • Fig. 1 shows a flowchart of a grid frequency detection method according to an exemplary embodiment of the present disclosure.
  • the grid frequency detection method may be executed by a converter of a wind power generating set (for example, a controller of the converter).
  • the grid frequency detection method may be periodically executed according to a preset grid frequency detection cycle T.
  • step S101 the collected three-phase voltage at the grid-connected point is transformed into a two-phase voltage.
  • the grid frequency detection method may further include: collecting the three-phase voltage of the grid-connected point at high frequency, so as to realize the high precision and high response speed requirements of grid frequency and its change rate detection.
  • the collected three-phase voltages v a , v b , and v c of the grid-connected point can be filtered first, and then the filtered three-phase voltage Perform Clark equal-amplitude transformation (for example, T ⁇ in Figure 2 represents the Clark transformation matrix) to obtain two-phase voltages to achieve dimensionality reduction.
  • a band-pass filter can be performed on the collected three-phase voltage of the grid-connected point (for example, BPF in Figure 2 represents a band-pass filter).
  • the center frequency of the band-pass filter can be: the rated frequency of the grid or the previous grid
  • the grid frequency detected by the frequency detection cycle ie, the grid frequency detected by executing the grid frequency detection method according to the exemplary embodiment of the present disclosure in the last grid frequency detection cycle.
  • the main function of the band-pass filter is to filter out high-frequency spurious signals, integer harmonics and sub-supersynchronous harmonics in the three-phase voltage sampling signal to obtain a relatively pure voltage fundamental component.
  • the three-phase voltage digital signal collected at high frequency can be filtered through a digital band-pass filter, wherein the center frequency of the band-pass filter can be self-adapted according to the instantaneous frequency of the grid detected by the grid frequency detection method Adjust or fix to grid rated frequency.
  • the main function of the filter is to filter out high-frequency stray signals, integer harmonics and sub-supersynchronous harmonics in the three-phase voltage sampling signal to obtain relatively pure voltage fundamental components.
  • the band-pass filter can be realized by a hardware circuit, or can be obtained by subtracting the original signal from the original signal after passing through the band-stop filter, or can be realized by adding a low-pass filter to a high-pass filter,
  • the present disclosure does not limit its implementation.
  • step S102 the two-phase voltages are transformed based on the phase angle of a specific frequency to obtain a voltage positive sequence component and a voltage negative sequence component to be decoupled.
  • the phase angle ⁇ may be obtained by integrating a specific angular velocity, where the frequency corresponding to the specific angular velocity is the specific frequency.
  • the phase angle (that is, the phase angle) used in the current grid frequency detection cycle is: the angle after superimposing T*w on the basis of the phase angle used in the previous grid frequency detection cycle, where T is the length of the grid frequency detection period, w is the specific angular velocity (that is, 2 ⁇ f, f is the specific frequency).
  • T the length of the grid frequency detection period
  • w the specific angular velocity (that is, 2 ⁇ f, f is the specific frequency).
  • 2 ⁇ may be subtracted so that the phase angle is always in the range of 0 ⁇ 2 ⁇ .
  • the specific angular velocity may be the rated angular velocity of the grid (that is, the specific frequency is the rated frequency of the grid), and it should be understood that the specific angular velocity may also be other fixed angular velocity.
  • the frequency corresponding to the fixed angular velocity needs to be greater than the cut-off frequency of the LPF in the "BSF+LPF" module shown in Figure 2, so as to improve the calculation accuracy of the grid frequency.
  • This way of obtaining the phase angle can improve the speed and stability of grid frequency detection, so as to avoid affecting the grid frequency and its change rate detection response time and stability under special working conditions.
  • phase angle ⁇ may be used to perform Park transformation on the two-phase voltages obtained by the Clark equal-amplitude transformation to obtain the voltage positive sequence component and the voltage negative sequence component to be decoupled.
  • positive and negative sequence rotating coordinate transformations can be performed on the two-phase voltages based on the phase angles to obtain the positive sequence components of the voltage to be decoupled in the positive sequence rotating coordinate system and the positive sequence components in the negative sequence rotating coordinate system.
  • the negative sequence component of the voltage to be decoupled can be performed.
  • the positive sequence rotating coordinate system and the negative sequence rotating coordinate system form a double synchronous rotating coordinate system.
  • T dq in Figure 2 represents the Park transformation matrix.
  • step S103 decoupling the voltage positive sequence component and voltage negative sequence component to be decoupled based on the phase angle, and filtering the decoupled voltage positive sequence component to obtain the voltage positive sequence fundamental wave component.
  • the grid frequency detection method may further include: filtering the decoupled voltage negative-sequence component to obtain the voltage negative-sequence fundamental wave component.
  • the negative-sequence fundamental wave component of the voltage obtained in the previous grid frequency detection period can be used to perform cross-feedback decoupling on the positive-sequence voltage component to be decoupled, and the positive-sequence component of the decoupled voltage (including decoupled positive-sequence voltage d-axis component and positive-sequence voltage q-axis component); and based on the phase angle, use the voltage positive-sequence fundamental wave component obtained in the previous grid frequency detection cycle to cross the negative-sequence voltage component to be decoupled Feedback decoupling to obtain decoupled voltage negative sequence components (including decoupled negative sequence voltage d-axis components and negative sequence voltage q-axis components).
  • n represents the number of positive sequence components
  • m represents the number of negative sequence components
  • d n represents n times of positive sequence d-axis components
  • q n represents n times of positive sequence q-axis Component
  • d m means m times negative sequence d-axis component
  • q m means m times negative sequence q axis component
  • Indicates the n times positive sequence d-axis component after decoupling Indicates the n times positive sequence q-axis component after decoupling
  • Indicates n times positive sequence voltage q-axis component Indicates the m-th negative sequence voltage d-axis component
  • the voltage positive sequence component and the voltage negative sequence component obtained by Park transformation can be decoupled according to formula (1) and formula (2).
  • the values of m and n can be other values according to the calculation performance of the controller, and the larger the value, the more accurate the calculation is.
  • band-stop BSF filtering and low-pass LPF filtering may be performed on the decoupled voltage positive sequence component to obtain the voltage positive sequence fundamental component.
  • band-stop BSF filtering and low-pass LPF filtering may be performed on the decoupled negative-sequence voltage component to obtain the negative-sequence fundamental wave component of the voltage.
  • the center frequency of the band-stop filter can be: the rated frequency of the grid or the grid frequency detected in the last grid frequency detection cycle to filter out the positive-sequence second harmonic in the grid and the positive-sequence The second harmonic of the sequence and the interference signal of the negative sequence to the high frequency of the positive sequence voltage.
  • the specific frequency may be higher than the cut-off frequency of the low-pass filter here.
  • the low-pass filter can filter out the influence of the negative sequence component on the positive sequence component and other high-frequency signals to obtain the positive sequence fundamental wave d-axis and q-axis components.
  • the "BSF+LPF” module represents a band-stop filter and a low-pass filter; Indicates the d-axis component of positive sequence voltage after filtering; Indicates the q-axis component of the positive sequence voltage after filtering; Indicates the d-axis component of negative sequence voltage after filtering; Indicates the q-axis component of the filtered m-order negative sequence voltage.
  • step S104 an inverse transformation is performed on the forward-sequence fundamental wave component of the voltage based on the phase angle to obtain a set of orthogonal voltage components in a two-phase stationary coordinate system.
  • T dq/ ⁇ represents the inverse Park transformation matrix; Indicates the ⁇ -axis component of the stationary coordinate system; Indicates the ⁇ -axis component of the stationary coordinate system.
  • step S105 the grid phase angle is obtained based on the set of quadrature voltage components.
  • the quadrature voltage components can be calculated and The arc tangent or inverse cotangent of , find the phase angle of the grid.
  • the value of Arctan v ⁇ /v ⁇ can be used as the grid phase angle.
  • step S106 the grid frequency is obtained based on the grid phase angle.
  • the grid frequency detection method may further include: obtaining a grid frequency change rate based on the grid phase angle.
  • a differential calculation can be done on the grid phase angle (e.g., in Figure 2 Represents the differentiator) to get the grid frequency.
  • an adaptive dynamic sliding window filter (for example, VFA in Figure 2 represents an adaptive dynamic sliding window filter) can be used to filter the calculated grid frequency; the filtered Grid frequency re-differentiation calculates grid frequency change rate.
  • the calculated rate of change of frequency may be filtered by a low-pass filter (for example, LPF in FIG. 2 represents a low-pass filter), and the filtering result may be used as the finally detected rate of change of grid frequency df/dt.
  • differential calculation may be first performed on the phase angle of the grid to obtain the first frequency; then, the first frequency may be filtered to obtain the second frequency; and then, the grid frequency may be obtained based on the second frequency.
  • adaptive dynamic sliding window filtering and/or low-pass filtering may be performed on the first frequency.
  • differential calculation may be performed on the second frequency to obtain the rate of change of the second frequency; and the rate of change of the second frequency may be filtered to obtain the rate of change of the grid frequency.
  • the rate of change of the second frequency may be low pass filtered.
  • the product of the grid frequency change rate and the frequency compensation coefficient K may be superimposed on the second frequency, and the superimposed result may be used as the finally detected grid frequency f.
  • Compensating the grid frequency according to the detected grid frequency change rate can further improve grid frequency detection accuracy and response time. It should be understood that the detected grid frequency may also be compensated in other ways, which is not limited in the present disclosure, for example, by adding a fixed value.
  • Fig. 3 shows a flowchart of a grid frequency regulation method according to an exemplary embodiment of the present disclosure.
  • the grid frequency regulation method may be applicable to direct-drive wind power generators and/or semi-direct-drive wind power generators for grid frequency regulation.
  • the grid frequency regulation method may be performed by a converter of a wind power generating set (for example, a controller of the converter).
  • step S201 it is determined whether there is a disturbance in the amplitude of the three-phase voltage at the grid-connected point.
  • the decoupled voltage positive sequence component and the voltage positive sequence fundamental wave component obtained by filtering the decoupled voltage positive sequence component it can be determined whether there is a disturbance in the three-phase voltage amplitude of the grid connection point.
  • the decoupled voltage positive-sequence component and the filtered voltage positive-sequence fundamental component are obtained by performing the grid frequency detection method described with reference to FIG. 1 .
  • the modulus of the high-frequency signal in the decoupled voltage positive-sequence component can be obtained based on the decoupled voltage positive-sequence component and the filtered voltage positive-sequence fundamental component; and when the high-frequency signal When the modulus value of is greater than the preset threshold, it is determined that there is a disturbance in the three-phase voltage amplitude of the grid-connected point.
  • the modulus of the high-frequency signal can be calculated by calculating the modulus of the pre-filtered and filtered signals, so as to determine whether a disturbance occurs.
  • formula (3) or (4) can be used to calculate the modulus ⁇ of the high frequency signal in the decoupled voltage positive sequence component. It should be understood that by There are many ways to calculate disturbance components (for example, high-frequency components) of the four variables, which are not limited in the present disclosure.
  • the proposed formula (3) can effectively avoid the influence of low-frequency components in the signal on the calculation of high-frequency components.
  • the calculation of the disturbance amount is realized by formula (3), which can effectively extract high-frequency disturbance components and avoid the influence of low-frequency components on the calculation. In addition, it can also be calculated according to formula (4).
  • Calculation of the disturbance amount can be realized through formula (3), which can effectively extract high-frequency disturbance components and avoid the influence of low-frequency components on the calculation. It can also be calculated according to formula (4), or other variables of the four variables in formula (3) can be used. Volume calculation method.
  • This disclosure considers that the change and fluctuation of the three-phase voltage at the grid-connected point caused by the switching of filter capacitors, etc., will cause disturbances in the detection of frequency and its change rate, because the power grid frequency detection method proposed in this disclosure is based on the grid-connected point
  • the three-phase voltage is obtained, so when some actions of the unit cause voltage fluctuations and disturbances at the grid-connected point, it will cause a disturbance in the grid frequency detection, but in fact this disturbance is not the frequency disturbance of the grid itself, but the wind turbine.
  • the detected grid frequency disturbance caused by the grid point voltage disturbance is the disturbance on the frequency detection value caused by the abnormal fluctuation of the voltage amplitude of the grid-connected point of the wind turbine (including filter capacitor switching, high and low wear, etc.), that is, and The disturbance of the frequency measurement caused by the amplitude fluctuation of the network point voltage.
  • step S202 is executed to determine whether the grid frequency regulation response condition is met according to the detected grid frequency and/or grid frequency change rate.
  • the grid frequency and/or the grid frequency change rate are detected by executing the grid frequency detection method described with reference to FIG. 1 .
  • the grid frequency detection method described with reference to FIG. 1 may be executed first, and then the grid frequency adjustment method described with reference to FIG.
  • the positive sequence component of the voltage and the positive sequence fundamental wave component of the voltage obtained after filtering to perform step S201, and when it is determined that there is no disturbance, perform step S202 according to the detection result of the current grid frequency (that is, the grid frequency and its rate of change) and step S203.
  • step S202 and step S203 are executed, so that the frequency and change rate detection based on the three-phase voltage signal of the power grid can be solved in the switching of filter capacitors. , Sudden power increase, high voltage ride through, inertia caused by disturbance during low voltage ride through, and a frequency modulation error response problem.
  • the grid frequency regulation response condition may include: an inertia response condition and/or a primary frequency regulation response condition.
  • step S203 is executed to control the power of the wind power generating set based on the grid frequency and/or the grid frequency change rate, so as to adjust the grid frequency.
  • the inertia response may be performed by controlling the power of the wind turbine based on the grid frequency change rate when only the inertia response condition is satisfied.
  • the primary frequency regulation may be performed by controlling the power of the wind power generating set based on the grid frequency and its rate of change when only the primary frequency regulation response condition is satisfied.
  • the inertia response when the inertia response condition and the primary frequency modulation response condition are satisfied at the same time, the inertia response may be performed preferentially by controlling the power of the wind turbine generator set based on the grid frequency change rate, so as to provide active power support for the grid inertia.
  • the inertia response when the inertia response condition and the primary frequency modulation response condition are satisfied at the same time, the inertia response is performed first, that is, the inertia response is performed first, and the primary frequency modulation response is not performed.
  • the present disclosure considers that in practice, the inertia response of the power grid often occurs before a frequency modulation, and the inertia response time requirement is high, at the millisecond level, and the duration is short; while the primary frequency modulation response time requirement is low, at the second level, and the duration is long. Therefore, the disclosure proposes: if the current grid frequency or its rate of change satisfies the response condition, the active power increment is calculated according to the inertia response priority principle.
  • the active power increment under the current grid frequency and its rate of change can be calculated according to the virtual inertia equation.
  • it can be set according to specific test standards, such as the judgment condition of whether the inertia response is active or not, as shown in the following formula (5).
  • the primary frequency modulation response condition can also be set according to standard requirements.
  • the requirements of the national standard are as follows: when the wind turbine is operating under the power-limited frequency regulation condition and the active output is greater than 20% Pn, when the frequency deviation of the test point exceeds the threshold (recommended ⁇ 0.2Hz), the wind turbine should be able to participate in system frequency regulation, Support system frequency recovery.
  • the inertia response active power increment can be calculated according to formula (6) (the national standard requires that the active power increment be calculated according to formula (6) to realize the inertia response active power support). It should be understood that the incremental active work can be positive or negative.
  • the corresponding active power increment can also be calculated according to standard requirements.
  • the target value of active power increment of the wind power generating set can be determined; based on the target value of active power increment and the rotational speed of the generator, the additional torque value of the generator can be calculated ; Based on the torque value of the generator and the additional torque value, calculate the target torque value of the generator; control the torque of the generator based on the target torque value of the generator, so as to control the power of the wind power generating set.
  • the calculated active power increment target value can be uploaded to the main controller of the unit (or the machine-side controller of the converter); and the generator speed to calculate the additional torque; the main controller of the unit or the machine-side controller of the converter can superimpose the current torque with the additional torque value and send it to the machine-side controller of the converter for execution.
  • the direct drive/semi-direct drive units stand-alone inertia response and primary frequency modulation response scheme can calculate the active power support increment through high-precision grid frequency and its change rate detection, and the whole machine will perform corresponding power control according to the active power increment value.
  • the active output of wind turbines can be changed to provide active support for grid inertia through the control method of converting the active power increment into the kinetic energy of the impeller and rotor. Due to the short response time and duration, the active power output of the unit can be changed by converting the active power increment into the motor torque control method to provide active power support for the grid inertia.
  • the following two methods can be adopted: (1) By controlling the pitch angle, adjust the wind energy captured by the wind turbine to make the system implement the active power increment requirement (2) A control method that converts the active power increment into the kinetic energy of the impeller and rotor, changes the active power output of the wind turbine, and provides a certain active power support for the grid frequency regulation; or a combination of the two can be used to realize the primary frequency modulation active power support.
  • the response time is required to be longer.
  • the kinetic energy of the rotor is used to provide active support, that is, the active support is realized through the torque control of the generator, and the stability of the generator speed is sacrificed.
  • the pitch can be changed.
  • the aerodynamic power of the fan realizes active support.
  • the active power increment target value of the wind generating set can be determined; based on the active power increment target value, it is determined that each control cycle needs to be adjusted in a plurality of control cycles The active power increment value; then, according to the active power increment value that needs to be adjusted in each control cycle, the power of the wind turbine is controlled.
  • the multiple control cycles include the current control cycle and a certain number of subsequent control cycles, and the sum of active power incremental values to be adjusted in the multiple control cycles is the active power incremental target value.
  • the active power increment target value can be given according to the slope (that is, a small amount of multiple adjustments to the unit power), reducing the impact of power impact on the frequency detection of the power grid, and solving the problem of the frequency detection caused by the inertia response of the unit when the active power is supported.
  • the slope setting method of active power can also be realized by low-pass filtering.
  • the calculated active power increment target value can also be limited, and the active power increment target value can be given according to the slope. By limiting the active power increment and setting the slope, the impact of power impact on grid frequency detection can be reduced.
  • the grid frequency adjustment method may further include: judging whether to exit the inertia response and/or primary frequency regulation control mode according to the grid frequency and its rate of change; The incremental target value is set to 0, and the active power incremental target value is given according to the slope.
  • Fig. 4 shows a flowchart of a grid frequency regulation method according to another exemplary embodiment of the present disclosure.
  • step S301 the collected three-phase voltage of the grid-connected point is transformed into a two-phase voltage.
  • step S302 the two-phase voltages are transformed based on the phase angle of a specific frequency to obtain a voltage positive sequence component and a voltage negative sequence component to be decoupled.
  • step S303 decoupling the voltage positive sequence component and voltage negative sequence component to be decoupled based on the phase angle, and filtering the decoupled voltage positive sequence component to obtain the voltage positive sequence fundamental wave component.
  • step S304 the positive sequence fundamental component of the voltage is inversely transformed based on the phase angle to obtain a set of orthogonal voltage components in a two-phase stationary coordinate system.
  • step S305 the grid phase angle is obtained based on the set of quadrature voltage components.
  • step S306 the grid frequency and the grid frequency change rate are obtained based on the grid phase angle.
  • step S307 it is determined whether there is a disturbance in the amplitude of the three-phase voltage at the grid-connected point.
  • step S308 is executed to determine whether the grid frequency regulation response condition is satisfied according to the detected grid frequency and/or grid frequency change rate.
  • step S309 is executed to control the power of the wind power generating set based on the grid frequency and/or the grid frequency change rate, so as to adjust the grid frequency.
  • the grid frequency and grid frequency change rate detection accuracy can reach: frequency measurement accuracy: less than 0.001 Hz; frequency change rate measurement accuracy: less than 0.002 Hz/s.
  • Grid frequency and grid frequency change rate response time can reach: frequency and frequency change rate detection time: less than 100ms.
  • the total inertia response time can be less than 500ms.
  • the frequency offset adaptability it can meet the precise detection within the range of 40Hz-70Hz.
  • the voltage offset adaptability it can satisfy the precise detection of the grid voltage within the range of 10% pu-150% pu.
  • the two-phase voltage drops to 10% pu, the two-phase voltage rises to 150% pu, and the frequency and frequency change rate detection accuracy and response time meet the requirements.
  • voltage harmonic adaptability the 2nd, 3rd, 5th, 7th and other single voltage harmonic content is less than 5%, or the total harmonic content is less than 5%, which can meet the detection accuracy and response time requirements of frequency and frequency change rate.
  • phase mutation adaptability it can meet the frequency, frequency change rate detection accuracy and response time requirements.
  • the absolute value of the control precision of active power shall not exceed 2% Pn.
  • the inertia and primary FM false response problem Under the condition that the unit does not add additional hardware, the proposed method can be run in the converter controller, so as to realize rapid development, new model application and field transformation. It solves the problem that the frequency change rate of the grid frequency and the oscillation of the active power support are caused by the disturbance of the frequency detection caused by the inertia response of the unit during the active power support.
  • the inertia response test waveform shown in Figure 5 when the grid frequency changes from 50Hz to 48Hz, the grid frequency change rate is -0.5Hz/s, as shown in the first waveform in Figure 5, the calculated active power increment is 0.07Pn, The actual waveform is shown in the second waveform in Figure 5.
  • the active power increment increases from 0.85Pn to 0.92Pn. Since the active support is realized through the rotor kinetic energy, the rotational speed decreases slowly during the active support process, as shown in the third waveform in Figure 5. Show.
  • the frequency of the power grid changes from 48Hz to 50Hz, which does not meet the response conditions, and the active power output of the unit remains unchanged.
  • the frequency modulation test waveform shown in Figure 6 when the grid frequency changes from 50Hz to 50.5Hz, as shown in the first waveform in Figure 6, according to the active power requirement, the active power increment target value is -0.16Pn, and the actual waveform is shown in the figure 6 As shown in the second waveform, the active power increment increases from 0.81Pn to 0.65Pn, and with the action of pitch change, the rotational speed reaches a stable value, as shown in the third waveform in Figure 6.
  • the active power output of the unit starts to recover.
  • Fig. 7 shows a structural block diagram of a power grid frequency detection device according to an exemplary embodiment of the present disclosure.
  • the grid frequency detection device includes: a two-phase voltage acquisition unit 101, a transformation unit 102, a decoupling filter unit 103, an inverse transformation unit 104, a grid phase angle acquisition unit 105, a grid frequency Acquisition unit 106.
  • the two-phase voltage acquiring unit 101 is configured to transform the acquired three-phase voltage of the grid-connected point into a two-phase voltage.
  • the transformation unit 102 is configured to transform the two-phase voltages based on the phase angle of a specific frequency to obtain a voltage positive sequence component and a voltage negative sequence component to be decoupled.
  • the decoupling filtering unit 103 is configured to decouple the voltage positive sequence component and the voltage negative sequence component to be decoupled based on the phase angle, and filter the decoupled voltage positive sequence component to obtain the voltage positive sequence fundamental component .
  • the inverse transformation unit 104 is configured to inversely transform the forward-sequence fundamental wave component of the voltage based on the phase angle to obtain a set of orthogonal voltage components in a two-phase stationary coordinate system.
  • the grid phase angle obtaining unit 105 is configured to obtain the grid phase angle based on the set of quadrature voltage components.
  • the grid frequency obtaining unit 106 is configured to obtain the grid frequency based on the grid phase angle.
  • the phase angle may be obtained by integrating a specific angular velocity; wherein the frequency corresponding to the specific angular velocity is the specific frequency.
  • the two-phase voltage acquisition unit 101 may be configured to band-pass filter the collected three-phase voltage of the grid-connected point; and perform Clark equal-amplitude conversion on the band-pass filtered three-phase voltage to obtain the two-phase voltage; , the center frequency of the band-pass filter is: the rated frequency of the grid or the grid frequency detected in the last grid frequency detection cycle.
  • the transformation unit 102 may be configured to perform positive and negative sequence rotation coordinate transformation on the two-phase voltage based on the phase angle, to obtain the positive sequence component of the voltage to be decoupled and the negative sequence rotation coordinate in the positive sequence rotation coordinate system
  • the negative-sequence component of the voltage to be decoupled under the system wherein, the positive-sequence rotating coordinate system and the negative-sequence rotating coordinate system constitute a dual synchronous rotating coordinate system.
  • the decoupling filtering unit 103 may be configured to filter the decoupled voltage negative sequence component to obtain the voltage negative sequence fundamental wave component.
  • the decoupling filtering unit 103 may be configured to perform cross-feedback decoupling on the voltage positive sequence component to be decoupled using the negative sequence fundamental wave component of the voltage obtained in the last grid frequency detection cycle based on the phase angle, to obtain decoupling and based on the phase angle, use the voltage positive sequence fundamental wave component obtained in the previous grid frequency detection cycle to perform cross-feedback decoupling on the voltage negative sequence component to be decoupled, and obtain the decoupled voltage negative sequence component ordinal component.
  • the decoupling filtering unit 103 may be configured to perform band-stop filtering and low-pass filtering on the decoupled voltage positive sequence component to obtain the voltage positive sequence fundamental component; wherein, the center frequency of the band-stop filtering is: The grid rated frequency or the grid frequency detected in the last grid frequency detection cycle; wherein, the specific frequency is higher than the cut-off frequency of the low-pass filter.
  • the grid frequency acquiring unit 106 may be configured to perform differential calculation on the grid phase angle to obtain a first frequency; filter the first frequency to obtain a second frequency; and based on the second frequency, obtain the grid frequency .
  • the power grid frequency detection device may further include: a grid frequency change rate acquisition unit (not shown), the grid frequency change rate acquisition unit is configured to perform differential calculation on the second frequency to obtain a change rate of the second frequency; And the rate of change of the second frequency is filtered to obtain the rate of change of the grid frequency.
  • a grid frequency change rate acquisition unit (not shown)
  • the grid frequency change rate acquisition unit is configured to perform differential calculation on the second frequency to obtain a change rate of the second frequency
  • the rate of change of the second frequency is filtered to obtain the rate of change of the grid frequency.
  • the grid frequency acquisition unit 106 may be configured to superimpose the product of the grid frequency change rate and the frequency compensation coefficient to the second frequency, and use the superimposed result as the grid frequency.
  • Fig. 8 shows a structural block diagram of a power grid frequency regulating device according to an exemplary embodiment of the present disclosure.
  • the grid frequency regulating device includes: a voltage disturbance judging unit 201 , a response condition judging unit 202 , and a grid frequency regulating unit 203 .
  • the voltage disturbance judging unit 201 is configured to determine whether there is a disturbance in the amplitude of the three-phase voltage at the grid-connected point.
  • the response condition judging unit 202 is configured to determine whether the grid frequency adjustment response condition is satisfied according to the detected grid frequency and/or grid frequency change rate when there is no disturbance.
  • the grid frequency adjustment unit 203 is configured to control the power of the wind power generating set based on the grid frequency and/or the grid frequency change rate when the grid frequency adjustment response condition is satisfied, so as to adjust the grid frequency.
  • the grid frequency and/or the grid frequency change rate are obtained by the grid frequency detection device described in the above exemplary embodiments.
  • the voltage disturbance judging unit 201 may be configured to determine the three-phase voltage at the grid-connected point based on the decoupled voltage positive sequence component and the voltage positive sequence fundamental wave component obtained by filtering the decoupled voltage positive sequence component Whether there is a disturbance in the amplitude; wherein, the decoupled positive-sequence voltage component and the filtered positive-sequence fundamental component of the voltage are obtained through the power grid frequency detection device described in the above exemplary embodiments.
  • the voltage disturbance judging unit 201 may be configured to obtain the modulus value of the high frequency signal in the decoupled voltage positive sequence component based on the decoupled voltage positive sequence component and the filtered voltage positive sequence fundamental component ; and when the modulus value of the high-frequency signal is greater than a preset threshold, it is determined that there is a disturbance in the three-phase voltage amplitude of the grid-connected point.
  • the grid frequency regulation response condition may include: an inertia response condition and a primary frequency regulation response condition.
  • the response condition judging unit 202 may be configured to determine whether the inertia response condition is satisfied according to the grid frequency and the grid frequency change rate; determine whether the primary frequency modulation response condition is satisfied according to the grid frequency; wherein, the grid frequency
  • the adjustment unit 203 may be configured to perform inertia response by preferentially controlling the power of the wind power generating set based on the grid frequency change rate when the inertia response condition and the primary frequency modulation response condition are satisfied at the same time.
  • the grid frequency adjustment unit 203 may be configured to determine the active power increment target value of the wind power generating set based on the grid frequency and/or the grid frequency change rate; based on the active power increment target value and the rotation speed of the generator, Calculate the additional torque value of the generator; calculate the target torque value of the generator based on the torque value of the generator and the additional torque value; and control the torque of the generator based on the target torque value of the generator to control the wind power The power of the generator set.
  • the grid frequency adjustment unit 203 may be configured to determine the active power increment target value of the wind power generating set based on the grid frequency and/or the grid frequency change rate; The active power incremental value that needs to be adjusted in each control cycle, wherein, the multiple control cycles include the current control cycle and its subsequent control cycle; and according to the active power incremental value that needs to be adjusted in each control cycle, control the wind turbine The power; wherein, the sum of the active power increment values that need to be adjusted in the multiple control cycles is the active power increment target value.
  • each unit in the grid frequency detection device and the grid frequency adjustment device may be implemented as hardware components and/or software components.
  • Those skilled in the art may implement each unit, for example, by using a Field Programmable Gate Array (FPGA) or an Application Specific Integrated Circuit (ASIC) according to the defined processing performed by each unit.
  • FPGA Field Programmable Gate Array
  • ASIC Application Specific Integrated Circuit
  • Exemplary embodiments of the present disclosure provide a computer-readable storage medium storing a computer program.
  • the processor is prompted to perform grid frequency detection as described in the above-mentioned exemplary embodiments. method and/or grid frequency regulation method.
  • the computer readable storage medium is any data storage device that can store data that is read by a computer system. Examples of computer-readable storage media include: read-only memory, random-access memory, compact disc-read-only, magnetic tape, floppy disk, optical data storage devices, and carrier waves (such as data transmission over the Internet via wired or wireless transmission paths).
  • An electronic device includes: a processor (not shown) and a memory (not shown), wherein the memory stores a computer program that, when executed by the processor, causes the The processor executes the grid frequency detection method and/or the grid frequency adjustment method as described in the above exemplary embodiments.
  • the electronic device may be a controller of a wind power plant or a converter (eg a controller of a converter).
  • Exemplary embodiments of the present disclosure provide a computer program that can be downloaded from a communication network and/or stored on a machine-readable storage medium, which is used to implement the power grid frequency detection method described in the above-mentioned exemplary embodiments, and /or program code instructions for implementing the grid frequency adjustment method described in the above exemplary embodiments.

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Abstract

一种电网频率检测方法和装置及电网频率调节方法和装置。电网频率检测方法包括：将采集的并网点的三相电压变换为两相电压（S101）；基于特定频率的相角对两相电压进行变换，得到待解耦的电压正序分量和电压负序分量（S102）；基于相角对待解耦的电压正序分量和电压负序分量进行解耦，并对解耦后的电压正序分量进行滤波，得到电压正序基波分量（S103）；基于相角对电压正序基波分量进行反变换，得到两相静止坐标系下的一组正交电压分量（S104）；基于一组正交电压分量，得到电网相角（S105）；基于电网相角，得到电网频率（S106）。

Description

电网频率检测方法和装置及电网频率调节方法和装置 技术领域
本公开总体说来涉及电力技术领域，更具体地讲，涉及一种电网频率检测方法和装置及电网频率调节方法和装置。
背景技术
风电场并网需具备惯量响应与一次调频的功能。大型风力发电机组通过变流器接入电网，相比于传统电网的同步发电机(例如，火电、水电的发电机)，具有控制灵活、响应迅速等优点。目前，风力发电机组参与惯量支撑和电网调频的主要方式是：转子动能控制方法和备用功率控制方法两种。而高精度的电网频率检测是实现惯量响应和一次调频的基础。
发明内容
本公开的示例性实施例在于提供一种电网频率检测方法和装置及电网频率调节方法和装置，其能够便捷、快速、准确地检测电网频率，并对电网频率进行有效调节。
根据本公开实施例的第一方面，提供一种电网频率检测方法，包括：将采集的并网点的三相电压变换为两相电压；基于特定频率的相角对所述两相电压进行变换，得到待解耦的电压正序分量和电压负序分量；基于所述相角对待解耦的电压正序分量和电压负序分量进行解耦，并对解耦后的电压正序分量进行滤波，得到电压正序基波分量；基于所述相角对所述电压正序基波分量进行反变换，得到两相静止坐标系下的一组正交电压分量；基于所述一组正交电压分量，得到电网相角；基于所述电网相角，得到电网频率。
根据本公开实施例的第二方面，提供一种电网频率调节方法，包括：确定并网点的三相电压幅值是否存在扰动；当不存在扰动时，根据检测的电网频率和/或电网频率变化率，确定是否满足电网频率调节响应条件；当满足所述电网频率调节响应条件时，基于所述电网频率和/或所述电网频率变化率控制风力发电机组的功率，以对电网频率进行调节；其中，所述电网频率和/或 所述电网频率变化率通过执行如上所述的电网频率检测方法得到。
根据本公开实施例的第三方面，提供一种电网频率检测装置，包括：两相电压获取单元，被配置为将采集的并网点的三相电压变换为两相电压；变换单元，被配置为基于特定频率的相角对所述两相电压进行变换，得到待解耦的电压正序分量和电压负序分量；解耦滤波单元，被配置为基于所述相角对待解耦的电压正序分量和电压负序分量进行解耦，并对解耦后的电压正序分量进行滤波，得到电压正序基波分量；反变换单元，被配置为基于所述相角对所述电压正序基波分量进行反变换，得到两相静止坐标系下的一组正交电压分量；电网相角获取单元，被配置为基于所述一组正交电压分量，得到电网相角；电网频率获取单元，被配置为基于所述电网相角，得到电网频率。
根据本公开实施例的第四方面，提供一种电网频率调节装置，包括：电压扰动判断单元，被配置为确定并网点的三相电压幅值是否存在扰动；响应条件判断单元，被配置为当不存在扰动时，根据检测的电网频率和/或电网频率变化率，确定是否满足电网频率调节响应条件；电网频率调节单元，被配置为当满足所述电网频率调节响应条件时，基于所述电网频率和/或所述电网频率变化率控制风力发电机组的功率，以对电网频率进行调节；其中，所述电网频率和/或所述电网频率变化率通过如上所述的电网频率检测装置得到。
根据本公开实施例的第五方面，提供一种存储有计算机程序的计算机可读存储介质，当所述计算机程序被处理器执行时，促使所述处理器执行如上所述的电网频率检测方法和/或如上所述的电网频率调节方法。
根据本公开实施例的第六方面，提供一种电子设备，所述电子设备包括：处理器；存储器，存储有计算机程序，当所述计算机程序被处理器执行时，促使所述处理器执行如上所述的电网频率检测方法和/或如上所述的电网频率调节方法。
本公开的实施例提供的技术方案至少带来以下有益效果：
能够实现高精度、高响应速度的电网频率及其变化率检测，使电网频率及其变化率的检测精度满足所要求的技术指标；使电网频率及其变化率的检测时间较短；并且具有良好的电网不平衡适应性、谐波适应性、电压偏移适应性、频率偏移适应性；
解决了基于电网三相电压信号的电网频率及其变化率检测在滤波电容投切、突加功率、高电压穿越、低电压穿越期间产生扰动所造成的惯量和一次 调频误响应问题；
可在风力发电机组不添加额外硬件的条件下实现本公开所提出的电网频率检测方法和电网频率调节方法，从而实现快速开发、新机型应用及现场改造；
解决了风力发电机组惯量响应在有功支撑时对频率检测产生扰动而造成电网频率变化率和有功支撑的振荡问题；
根据检测得到的电网频率及其变化率，结合虚拟惯量方程计算有功增量，将有功增量转化为电机控制转矩指令，完成功率控制，进而实现机组惯量响应和一次调频。
将在接下来的描述中部分阐述本公开总体构思另外的方面和/或优点，还有一部分通过描述将是清楚的，或者可以经过本公开总体构思的实施而得知。
附图说明
通过下面结合示例性地示出实施例的附图进行的描述，本公开示例性实施例的上述和其他目的和特点将会变得更加清楚，其中：
图1示出根据本公开的示例性实施例的电网频率检测方法的流程图；
图2示出根据本公开的示例性实施例的电网频率检测方法的示例；
图3示出根据本公开的示例性实施例的电网频率调节方法的流程图；
图4示出根据本公开的另一示例性实施例的电网频率调节方法的流程图；
图5示出根据本公开的示例性实施例的惯量响应测试的示例；
图6示出根据本公开的示例性实施例的一次调频测试的示例；
图7示出根据本公开的示例性实施例的电网频率检测装置的结构框图；
图8示出根据本公开的示例性实施例的电网频率调节装置的结构框图。
具体实施方式
现将详细参照本公开的实施例，所述实施例的示例在附图中示出，其中，相同的标号始终指的是相同的部件。以下将通过参照附图来说明所述实施例，以便解释本公开。
图1示出根据本公开的示例性实施例的电网频率检测方法的流程图。作为示例，所述电网频率检测方法可由风力发电机组的变流器(例如，变流器的控制器)执行。作为示例，所述电网频率检测方法可根据预设的电网频率 检测周期T周期性地执行。
参照图1并结合图2，在步骤S101，将采集的并网点的三相电压变换为两相电压。
作为示例，根据本公开的示例性实施例的电网频率检测方法还可包括：高频采集并网点的三相电压，以实现电网频率及其变化率检测的高精度和高响应速度要求。
作为示例，可先对采集的并网点的三相电压v a、v b、v c(为描述方便起见，将此三相电压用v abc表示)进行滤波，然后，对滤波后的三相电压进行Clark等幅值变换(例如，图2中的T αβ表示Clark变换矩阵)，得到两相电压，实现降维。作为示例，可对采集的并网点的三相电压进行带通滤波(例如，图2中的BPF表示带通滤波器)，例如，带通滤波的中心频率可为：电网额定频率或上一电网频率检测周期检测得到的电网频率(即，上一电网频率检测周期通过执行根据本公开的示例性实施例的电网频率检测方法所检测得到的电网频率)。带通滤波的主要作用是滤去三相电压采样信号中的高频杂散信号、各整数次谐波及次超同步谐波等，以得到较为纯净的电压基波分量。
作为示例，可通过数字带通滤波器对高频采集的三相电压数字信号进行滤波，其中，带通滤波器的中心频率可根据通过所述电网频率检测方法所检测到的电网瞬时频率自适应调整或固定为电网额定频率。该滤波器的主要作用是滤去三相电压采样信号中的高频杂散信号、各整数次谐波及次超同步谐波，得到较为纯净的电压基波分量。例如，所述带通滤波器可通过硬件电路来实现，或者可通过将原始信号减去原始信号通过带阻滤波器后的值来得到，或者可通过低通滤波器加高通滤波器来实现，本公开对其实现方式不作限定。
在步骤S102，基于特定频率的相角对所述两相电压进行变换，得到待解耦的电压正序分量和电压负序分量。
作为示例，所述相角θ可通过对特定角速度进行积分得到，其中，所述特定角速度对应的频率为所述特定频率。具体地，当前电网频率检测周期所使用的相角(也即，所述相角)为：在上一电网频率检测周期所使用的相角的基础上叠加T*w之后的角度，其中，T为电网频率检测周期的长度，w为所述特定角速度(也即，2πf，f为所述特定频率)。作为示例，当角度超过2π时，可减去2π，以使相角始终处于0～2π范围内。
作为示例，所述特定角速度可为电网额定角速度(也即，所述特定频率 为电网额定频率)，应该理解，所述特定角速度也可为其它固定角速度。例如，该固定角速度对应的频率需大于图2所示“BSF+LPF”模块中的LPF的截止频率，以提高电网频率计算精度。
通过这一获取相角的方式能够提高电网频率检测的快速性和稳定性，以避免影响电网频率及其变化率检测响应时间和特殊工况下的稳定性。
作为示例，可使用所述相角θ，对Clark等幅值变换得到的两相电压进行Park变换，得到待解耦的电压正序分量和电压负序分量。
具体地，作为示例，可基于所述相角对所述两相电压进行正负序旋转坐标变换，得到正序旋转坐标系下的待解耦的电压正序分量和负序旋转坐标系下的待解耦的电压负序分量。其中，所述正序旋转坐标系和所述负序旋转坐标系构成双同步旋转坐标系。例如，图2中的T dq表示Park变换矩阵。
在步骤S103，基于所述相角对待解耦的电压正序分量和电压负序分量进行解耦，并对解耦后的电压正序分量进行滤波，得到电压正序基波分量。
作为示例，根据本公开的示例性实施例的电网频率检测方法还可包括：对解耦后的电压负序分量进行滤波，得到电压负序基波分量。
作为示例，可基于所述相角，使用上一电网频率检测周期得到的电压负序基波分量对待解耦的电压正序分量进行交叉反馈解耦，得到解耦后的电压正序分量(包括解耦后的正序电压d轴分量和正序电压q轴分量)；并基于所述相角，使用上一电网频率检测周期得到的电压正序基波分量对待解耦的电压负序分量进行交叉反馈解耦，得到解耦后的电压负序分量(包括解耦后的负序电压d轴分量和负序电压q轴分量)。
作为示例，如图2所示的交叉反馈解耦的示例，n表示正序分量次数；m表示负序分量次数；d n表示n次正序d轴分量；q n表示n次正序q轴分量；d m表示m次负序d轴分量；q m表示m次负序q轴分量；
Figure PCTCN2022102858-appb-000001
表示解耦后的n次正序d轴分量；
Figure PCTCN2022102858-appb-000002
表示解耦后的n次正序q轴分量；
Figure PCTCN2022102858-appb-000003
表示解耦后的m次负序d轴分量；
Figure PCTCN2022102858-appb-000004
表示解耦后的m次负序q轴分量；
Figure PCTCN2022102858-appb-000005
表示n次正序电压d轴分量；
Figure PCTCN2022102858-appb-000006
表示n次正序电压q轴分量；
Figure PCTCN2022102858-appb-000007
表示m次负序电压d轴分量；
Figure PCTCN2022102858-appb-000008
表示m次负序电压q轴分量；
Figure PCTCN2022102858-appb-000009
表示正序、负序解耦网络。
作为示例，可根据式(1)和式(2)实现解耦后的正序分量和负序分量 计算，若只考虑基波分量，则令n＝1，m＝-1。例如，可根据式(1)和式(2)对Park变换得到的电压正序分量和电压负序分量进行解耦。例如，m和n的值可根据控制器计算性能，采用其它值，值越大计算相对越精确。
Figure PCTCN2022102858-appb-000010
Figure PCTCN2022102858-appb-000011
作为示例，可对解耦后的电压正序分量进行带阻BSF滤波和低通LPF滤波，得到电压正序基波分量。相应地，作为示例，可对解耦后的电压负序分量进行带阻BSF滤波和低通LPF滤波，得到电压负序基波分量。例如，带阻滤波的中心频率可为：电网额定频率或上一电网频率检测周期检测得到的电网频率，以滤去电网中的正序二次谐波，滤除离电网基频较近的正序二次谐波及负序对正序电压中高频的干扰信号。例如，所述特定频率可高于这里的低通滤波的截止频率。低通滤波可滤除负序分量对正序分量及其它高频信号影响，以得到正序基波d轴和q轴分量。
作为示例，如图2所示，“BSF+LPF”模块表示带阻滤波器和低通滤波器；
Figure PCTCN2022102858-appb-000012
表示滤波后的n次正序电压d轴分量；
Figure PCTCN2022102858-appb-000013
表示滤波后的n次正序电压q轴分量；
Figure PCTCN2022102858-appb-000014
表示滤波后的m次负序电压d轴分量；
Figure PCTCN2022102858-appb-000015
表示滤波后的m次负序电压q轴分量。
在步骤S104，基于所述相角对所述电压正序基波分量进行反变换，得到两相静止坐标系下的一组正交电压分量。
作为示例，可如图2所示，基于所述相角θ对正序基波d轴和q轴分量进行反Park变换，得到一组正交信号
Figure PCTCN2022102858-appb-000016
和
Figure PCTCN2022102858-appb-000017
其中，T dq/αβ表示反Park变换矩阵；
Figure PCTCN2022102858-appb-000018
表示静止坐标系α轴分量；
Figure PCTCN2022102858-appb-000019
表示静止坐标系β轴分量。
在步骤S105，基于所述一组正交电压分量，得到电网相角。
作为示例，可计算正交电压分量
Figure PCTCN2022102858-appb-000020
和
Figure PCTCN2022102858-appb-000021
的反正切或反余切，求出电网相角。例如，可将Arctan v α/v β的值作为电网相角。
在步骤S106，基于所述电网相角，得到电网频率。
作为示例，根据本公开的示例性实施例的电网频率检测方法还可包括： 基于所述电网相角，得到电网频率变化率。
作为示例，可对电网相角做微分计算(例如，图2中的
Figure PCTCN2022102858-appb-000022
表示微分器)得到电网频率。作为示例，为进一步消除整数次谐波，可采用自适应动态滑窗滤波器(例如，图2中的VFA表示自适应动态滑窗滤波器)对计算得到的电网频率进行滤波；对滤波后的电网频率再微分计算电网频率变化率。作为示例，可通过低通滤波器(例如，图2中的LPF表示低通滤波器)对计算得到的频率变化率滤波，并将滤波结果作为最终检测到的电网频率变化率df/dt。
作为示例，可首先对所述电网相角进行微分计算，得到第一频率；然后，对第一频率进行滤波，得到第二频率；接下来，基于第二频率，得到所述电网频率。例如，可对第一频率进行自适应动态滑窗滤波和/或低通滤波。
作为示例，可对第二频率进行微分计算，得到第二频率的变化率；并对第二频率的变化率进行滤波，得到电网频率变化率。例如，可对第二频率的变化率进行低通滤波。
作为示例，可将所述电网频率变化率与频率补偿系数K的乘积叠加到第二频率，并将叠加后的结果作为最终检测到的电网频率f。根据检测到的电网频率变化率补偿电网频率，能够进一步提升电网频率检测精度和响应时间。应该理解，也可采用其它方式对检测的电网频率进行补偿，本公开对此不作限制，例如，通过加一固定值的方式。
图3示出根据本公开的示例性实施例的电网频率调节方法的流程图。作为示例，所述电网频率调节方法可适用于直驱风力发电机组和/或半直驱风力发电机组进行电网频率调节。作为示例，所述电网频率调节方法可由风力发电机组的变流器(例如，变流器的控制器)来执行。
参照图3，在步骤S201，确定并网点的三相电压幅值是否存在扰动。
作为示例，可基于解耦后的电压正序分量和对解耦后的电压正序分量进行滤波后得到的电压正序基波分量，确定并网点的三相电压幅值是否存在扰动，所述解耦后的电压正序分量和滤波后得到的电压正序基波分量通过执行参照图1所描述的电网频率检测方法得到。
作为示例，可基于解耦后的电压正序分量和滤波后得到的电压正序基波分量，得到解耦后的电压正序分量中的高频信号的模值；并当所述高频信号的模值大于预设阈值时，确定并网点的三相电压幅值存在扰动。
本公开考虑到发生扰动后
Figure PCTCN2022102858-appb-000023
中存在高频信号，而
Figure PCTCN2022102858-appb-000024
是通过对
Figure PCTCN2022102858-appb-000025
进行滤波得到的信号，不含有高频信号，因此，可通过对滤波前和滤波后的信号计算模值，求出高频信号的模值，以此判断是否发生扰动。作为示例，可使用公式(3)或(4)来计算解耦后的电压正序分量中的高频信号的模值δ。应该理解，通过
Figure PCTCN2022102858-appb-000026
四个变量计算扰动分量(例如，高频分量)的方法多种，本公开对此不作限制，所提出的公式(3)可以有效避免信号中低频分量对计算高频分量的影响。
Figure PCTCN2022102858-appb-000027
通过式(3)实现扰动量计算，可有效提取高频扰动分量，又避免低频分量对计算的影响，此外，也可按照式(4)计算。
Figure PCTCN2022102858-appb-000028
通过式(3)可实现扰动量计算，可有效提取高频扰动分量，又避免低频分量对计算的影响，也可按照式(4)计算，或采用公式(3)中四个变量的其它变体计算方式。
本公开考虑到：滤波电容投切等引起的并网点的三相电压的变化和波动，会造成频率及其变化率检测上的扰动，这是因为本公开提出的电网频率检测方法是基于并网点的三相电压得到的，所以当机组的一些动作造成并网点的电压波动和扰动时，就会造成电网频率检测的扰动，但实际上这个扰动不是电网本身的频率扰动，而是风力发电机组并网点电压扰动所造成的检测到的电网频率呈现扰动，为风力发电机组并网点电压幅值非正常波动(包括滤波电容投切、高低穿等)所造成的频率检测值上的扰动，即，并网点电压的幅值波动引起的测频的扰动。
当在步骤S201确定不存在扰动时，执行步骤S202，根据检测的电网频率和/或电网频率变化率，确定是否满足电网频率调节响应条件。
所述电网频率和/或所述电网频率变化率通过执行参照图1所描述的电网频率检测方法检测得到。
应该理解，可先执行参照图1所描述的电网频率检测方法，然后执行参 照图3所描述的电网频率调节方法，具体地，根据本次电网频率检测过程中的中间量(例如，解耦后的电压正序分量和滤波后得到的电压正序基波分量)来执行步骤S201，当确定不存在扰动时，根据本次电网频率的检测结果(即，电网频率及其变化率)执行步骤S202和步骤S203。
当并网点三相电压幅值存在扰动(例如，滤波电容投切，高低穿等引起的)时，会造成检测的电网频率出现扰动(但实际电网频率并没有扰动)。因此，先判断是否存在并网点三相电压幅值扰动，当不存在扰动时，才执行步骤S202和步骤S203，从而可解决基于电网三相电压信号的频率及其变化率检测在滤波电容投切、突加功率、高电压穿越、低电压穿越期间产生扰动所造成的惯量和一次调频误响应问题。
作为示例，电网频率调节响应条件可包括：惯量响应条件和/或一次调频响应条件。
作为示例，可根据所述电网频率及所述电网频率变化率，确定是否满足惯量响应条件；并根据所述电网频率，确定是否满足一次调频响应条件。
当在步骤S202确定满足电网频率调节响应条件时，执行步骤S203，基于所述电网频率和/或所述电网频率变化率控制风力发电机组的功率，以对电网频率进行调节。
作为示例，可当仅惯量响应条件满足时，通过基于所述电网频率变化率控制风力发电机组的功率，来进行惯量响应。作为示例，可当仅一次调频响应条件满足时，通过基于所述电网频率及其变化率控制风力发电机组的功率，来进行一次调频。
作为示例，可当惯量响应条件和一次调频响应条件同时满足时，优先通过基于所述电网频率变化率控制风力发电机组的功率，来进行惯量响应，以为电网惯量提供有功支持。换言之，当惯量响应条件和一次调频响应条件同时满足时，优先进行惯量响应，即当前先进行惯量响应，而不进行一次调频响应。
本公开考虑到，实际中电网惯量响应往往发生于一次调频之前，且惯量响应时间要求高，为毫秒级，持续时间短；而一次调频响应时间要求低，为秒级，持续时间长。因此，本公开提出：若当前电网频率或其变化率满足响应条件，按照惯量响应优先原则计算有功增量。
作为示例，当确定不存在扰动时，可判断电网频率及其变化率是否大于 死区；当满足时，判断机组当前功率是否大于20％Pn；当大于20％Pn时，可确定满足电网频率调节响应条件。然后，可根据虚拟惯量方程计算当前电网频率及其变化率下的有功增量。
作为示例，可按照具体测试标准设定，如惯量响应是否动作判断条件如下式(5)所示。
Figure PCTCN2022102858-appb-000029
其中，Δf＝f-f N，f表示检测的电网频率；f N表示电网额定频率；df 0表示频率变化率死区阈值。
对于一次调频响应条件，亦可按照标准要求设定。作为示例，如国标要求如下：风力发电机组运行在限功率调频工况且有功出力大于20％Pn时，当测试点的频率偏差超过阈值(推荐±0.2Hz)，风力发电机组应能参与系统调频，支撑系统频率恢复。
作为示例，惯量响应有功增量可按照式(6)计算(国标中要求按照公式(6)计算有功增量，实现惯量响应有功支撑)。应该理解，有功增量可为正值或负值。
Figure PCTCN2022102858-appb-000030
其中，ΔP表示有功增量(也即，有功增量目标值)；T J表示惯性时间常数；P N表示机组额定功率，f N表示电网额定频率；df/dt表示检测到的电网频率变化率。
此外，作为示例，对于一次调频，亦可按照标准要求计算相应的有功增量。
作为示例，可基于所述电网频率和/或所述电网频率变化率，确定风力发电机组的有功增量目标值；基于有功增量目标值及发电机的转速，计算发电机的附加转矩值；基于发电机的转矩值和附加转矩值，计算发电机的目标转矩值；基于发电机的目标转矩值控制发电机的转矩，以控制风力发电机组的功率。
作为示例，可将计算得到的有功增量目标值上传给机组主控器(或变流器的机侧控制器)；机组主控器或变流器的机侧控制器根据有功增量目标值及发电机转速计算附加转矩；机组主控器或变流器的机侧控制器可将当前的转矩叠加附加转矩值后下发给变流器机侧控制器执行。
例如，直驱/半直驱机组单机惯量响应及一次调频响应方案，可通过高精度电网频率及其变化率检测，计算有功支撑增量，整机根据有功增量值，执行相应的功率控制。
作为示例，对于惯量响应，由于要求响应时间及持续时间短，可通过将有功增量折算为叶轮及转子动能的控制方法，改变风力发电机组的有功出力，为电网惯量提供有功支撑。由于要求响应时间及持续时间短，可通过将有功增量折算为电机转矩控制方法，改变机组的有功出力，为电网惯量提供有功支撑。
作为示例，对于一次调频，由于要求响应时间及持续时间较长，可通过以下两种方法：(1)通过控制桨距角，调整风力发电机组对风能的捕获能量，使系统执行有功增量需求值；(2)将有功增量折算为叶轮及转子动能的控制方法，改变风力发电机组的有功出力，为电网频率调节提供一定的有功支撑；或者可通过两者结合实现一次调频有功支撑。进行一次调频有功支撑时，要求响应时间较长，一方面利用转子动能提供有功支撑，即通过对发电机的转矩控制上实现有功支撑，牺牲发电机转速的稳定，同时，可通过变桨改变风机气动功率实现有功支持。
作为示例，可基于所述电网频率和/或所述电网频率变化率，确定风力发电机组的有功增量目标值；基于有功增量目标值确定在多个控制周期中的每个控制周期需要调节的有功增量值；然后，按照每个控制周期需要调节的有功增量值，控制风力发电机组的功率。所述多个控制周期包括当前控制周期及其后续一定数量的控制周期，所述多个控制周期需要调节的有功增量值的总和为所述有功增量目标值。根据本实施例，可使有功增量目标值按照斜率给定(即，少量多次调节机组功率)，减小功率冲击对电网频率检测的影响，解决机组惯量响应在有功支撑时对频率检测产生扰动而造成电网频率变化率和有功支撑的振荡问题。此外，该有功功率的斜率给定方式也可以通过低通滤波方式实现。
此外，作为示例，还可对计算得到的有功增量目标值进行限幅，并使有功增量目标值按照斜率给定。通过对有功增量进行限幅处理及斜率给定，可减小功率冲击对电网频率检测的影响。
此外，作为示例，根据本公开的示例性实施例的电网频率调节方法还可包括：根据所述电网频率及其变化率判断是否退出惯量响应和/或一次调频控 制模式，如果退出，可将有功增量目标值设为0，并使有功增量目标值按照斜率给定。
图4示出根据本公开的另一示例性实施例的电网频率调节方法的流程图。
在步骤S301，将采集的并网点的三相电压变换为两相电压。
在步骤S302，基于特定频率的相角对所述两相电压进行变换，得到待解耦的电压正序分量和电压负序分量。
在步骤S303，基于所述相角对待解耦的电压正序分量和电压负序分量进行解耦，并对解耦后的电压正序分量进行滤波，得到电压正序基波分量。
在步骤S304，基于所述相角对所述电压正序基波分量进行反变换，得到两相静止坐标系下的一组正交电压分量。
在步骤S305，基于所述一组正交电压分量，得到电网相角。
在步骤S306，基于所述电网相角，得到电网频率和电网频率变化率。
在步骤S307，确定并网点的三相电压幅值是否存在扰动。
当在步骤S307确定不存在扰动时，执行步骤S308，根据检测的电网频率和/或电网频率变化率，确定是否满足电网频率调节响应条件。
当在步骤S308确定满足所述电网频率调节响应条件时，执行步骤S309，基于所述电网频率和/或所述电网频率变化率控制风力发电机组的功率，以对电网频率进行调节。
根据本公开的示例性实施例，电网频率及电网频率变化率检测精度可达到：频率测量精度：小于0.001Hz；频率变化率测量精度：小于0.002Hz/s。电网频率及电网频率变化率响应时间可达到：频率及频率变化率检测时间：小于100ms。惯量响应总时间可小于500ms。关于频率偏移适应性，可满足40Hz～70Hz范围内的精确检测。关于电压偏移适应性，可满足电网电压在10％pu～150％pu范围内的精确检测。关于三相不平适应性，两相跌落至10％pu，两相电压升高至150％pu，频率及频率变化率检测精度及响应时间满足要求。关于电压谐波适应性，2、3、5、7次等单次电压谐波含量小于5％，或总谐波含量小于5％，可满足频率、频率变化率检测精度及响应时间要求。关于相位突变适应性，可满足频率、频率变化率检测精度及响应时间要求。关于有功控制精度，有功控制精度，误差绝对值不超过2％Pn。
根据本公开的示例性实施例，解决了基于电网三相电压信号的频率及其变化率检测在滤波电容投切、突加功率、高电压穿越、低电压穿越期间产生 扰动所造成的惯量和一次调频误响应问题。在机组不添加额外硬件条件下，使所提出的方法运行在变流器控制器中，从而实现快速开发、新机型应用及现场改造。解决了机组惯量响应在有功支撑时对频率检测产生扰动而造成电网频率变化率和有功支撑的振荡问题。
结合图5和图6，给出通过本公开的示例性实施例的电网频率检测方法及电网频率调节方法进行惯量响应和一次调频的测试示例。
如图5所示的惯量响应测试波形，当电网频率从50Hz变化为48Hz期间，电网频率变化率为-0.5Hz/s，如图5第一个波形所示，计算有功增量为0.07Pn，实际波形如图5第二个波形所示，有功增量由0.85Pn增加到0.92Pn，由于通过转子动能实现有功支撑，因此在有功支撑过程中，转速缓慢下降，如图5第三个波形所示。电网频率从48Hz变为50Hz，不满足响应条件，机组有功输出不变。
如图6所示的一次调频测试波形，当电网频率从50Hz变化为50.5Hz期间，如图6第一个波形所示，按照有功要求，有功增量目标值为-0.16Pn，实际波形如图6第二个波形所示，有功增量由0.81Pn增加到0.65Pn，随着变桨动作，转速达到稳定值，如图6第三个波形所示。电网频率从50.5Hz变为50Hz过程中，机组有功输出开始恢复。
图7示出根据本公开的示例性实施例的电网频率检测装置的结构框图。
参照图7，根据本公开的示例性实施例的电网频率检测装置包括：两相电压获取单元101、变换单元102、解耦滤波单元103、反变换单元104、电网相角获取单元105、电网频率获取单元106。
具体说来，两相电压获取单元101被配置为将采集的并网点的三相电压变换为两相电压。
变换单元102被配置为基于特定频率的相角对所述两相电压进行变换，得到待解耦的电压正序分量和电压负序分量。
解耦滤波单元103被配置为基于所述相角对待解耦的电压正序分量和电压负序分量进行解耦，并对解耦后的电压正序分量进行滤波，得到电压正序基波分量。
反变换单元104被配置为基于所述相角对所述电压正序基波分量进行反变换，得到两相静止坐标系下的一组正交电压分量。
电网相角获取单元105被配置为基于所述一组正交电压分量，得到电网 相角。
电网频率获取单元106被配置为基于所述电网相角，得到电网频率。
作为示例，所述相角可通过对特定角速度进行积分得到；其中，所述特定角速度对应的频率为所述特定频率。
作为示例，两相电压获取单元101可被配置为对采集的并网点的三相电压进行带通滤波；并对带通滤波后的三相电压进行Clark等幅值变换，得到两相电压；其中，所述带通滤波的中心频率为：电网额定频率或上一电网频率检测周期检测得到的电网频率。
作为示例，变换单元102可被配置为基于所述相角对所述两相电压进行正负序旋转坐标变换，得到正序旋转坐标系下的待解耦的电压正序分量和负序旋转坐标系下的待解耦的电压负序分量；其中，所述正序旋转坐标系和所述负序旋转坐标系构成双同步旋转坐标系。
作为示例，解耦滤波单元103可被配置为对解耦后的电压负序分量进行滤波，得到电压负序基波分量。
作为示例，解耦滤波单元103可被配置为基于所述相角，使用上一电网频率检测周期得到的电压负序基波分量对待解耦的电压正序分量进行交叉反馈解耦，得到解耦后的电压正序分量；并基于所述相角，使用上一电网频率检测周期得到的电压正序基波分量对待解耦的电压负序分量进行交叉反馈解耦，得到解耦后的电压负序分量。
作为示例，解耦滤波单元103可被配置为对解耦后的电压正序分量进行带阻滤波和低通滤波，得到电压正序基波分量；其中，所述带阻滤波的中心频率为：电网额定频率或上一电网频率检测周期检测得到的电网频率；其中，所述特定频率高于所述低通滤波的截止频率。
作为示例，电网频率获取单元106可被配置为对所述电网相角进行微分计算，得到第一频率；对第一频率进行滤波，得到第二频率；并基于第二频率，得到所述电网频率。
作为示例，所述电网频率检测装置还可包括：电网频率变化率获取单元(未示出)，电网频率变化率获取单元被配置为对第二频率进行微分计算，得到第二频率的变化率；并对第二频率的变化率进行滤波，得到电网频率变化率。
作为示例，电网频率获取单元106可被配置为将所述电网频率变化率与 频率补偿系数的乘积叠加到第二频率，并将叠加后的结果作为所述电网频率。
图8示出根据本公开的示例性实施例的电网频率调节装置的结构框图。
参照图8，根据本公开的示例性实施例的电网频率调节装置包括：电压扰动判断单元201、响应条件判断单元202、电网频率调节单元203。
具体说来，电压扰动判断单元201被配置为确定并网点的三相电压幅值是否存在扰动。
响应条件判断单元202被配置为当不存在扰动时，根据检测的电网频率和/或电网频率变化率，确定是否满足电网频率调节响应条件。
电网频率调节单元203被配置为当满足所述电网频率调节响应条件时，基于所述电网频率和/或所述电网频率变化率控制风力发电机组的功率，以对电网频率进行调节。
所述电网频率和/或所述电网频率变化率通过如上述示例性实施例所述的电网频率检测装置得到。
作为示例，电压扰动判断单元201可被配置为基于解耦后的电压正序分量和对解耦后的电压正序分量进行滤波后得到的电压正序基波分量，确定并网点的三相电压幅值是否存在扰动；其中，所述解耦后的电压正序分量和滤波后得到的电压正序基波分量通过如上述示例性实施例所述的电网频率检测装置得到。
作为示例，电压扰动判断单元201可被配置为基于解耦后的电压正序分量和滤波后得到的电压正序基波分量，得到解耦后的电压正序分量中的高频信号的模值；并当所述高频信号的模值大于预设阈值时，确定并网点的三相电压幅值存在扰动。
作为示例，电网频率调节响应条件可包括：惯量响应条件和一次调频响应条件。
作为示例，响应条件判断单元202可被配置为根据所述电网频率及所述电网频率变化率，确定是否满足惯量响应条件；根据所述电网频率，确定是否满足一次调频响应条件；其中，电网频率调节单元203可被配置为当惯量响应条件和一次调频响应条件同时满足时，优先通过基于所述电网频率变化率控制风力发电机组的功率，来进行惯量响应。
作为示例，电网频率调节单元203可被配置为基于所述电网频率和/或所述电网频率变化率，确定风力发电机组的有功增量目标值；基于有功增量目 标值及发电机的转速，计算发电机的附加转矩值；基于发电机的转矩值和附加转矩值，计算发电机的目标转矩值；并基于发电机的目标转矩值控制发电机的转矩，以控制风力发电机组的功率。
作为示例，电网频率调节单元203可被配置为基于所述电网频率和/或所述电网频率变化率，确定风力发电机组的有功增量目标值；基于有功增量目标值确定在多个控制周期中的每个控制周期需要调节的有功增量值，其中，所述多个控制周期包括当前控制周期及其后续控制周期；并按照每个控制周期需要调节的有功增量值，控制风力发电机组的功率；其中，所述多个控制周期需要调节的有功增量值的总和为所述有功增量目标值。
应该理解，根据本公开示例性实施例的电网频率检测装置和电网频率调节装置所执行的具体处理已经参照图1至图6进行了详细描述，这里将不再赘述相关细节。
应该理解，根据本公开示例性实施例的电网频率检测装置和电网频率调节装置中的各个单元可被实现硬件组件和/或软件组件。本领域技术人员根据限定的各个单元所执行的处理，可以例如使用现场可编程门阵列(FPGA)或专用集成电路(ASIC)来实现各个单元。
本公开的示例性实施例提供一种存储有计算机程序的计算机可读存储介质，当所述计算机程序被处理器执行时，促使所述处理器执行如上述示例性实施例所述的电网频率检测方法和/或电网频率调节方法。该计算机可读存储介质是可存储由计算机系统读出的数据的任意数据存储装置。计算机可读存储介质的示例包括：只读存储器、随机存取存储器、只读光盘、磁带、软盘、光数据存储装置和载波(诸如经有线或无线传输路径通过互联网的数据传输)。
根据本公开的示例性实施例的电子设备包括：处理器(未示出)和存储器(未示出)，其中，存储器存储有计算机程序，当所述计算机程序被处理器执行时，促使所述处理器执行如上述示例性实施例所述的电网频率检测方法和/或电网频率调节方法。作为示例，所述电子设备可为风力发电机组的控制器或变流器(例如，变流器的控制器)。
本公开的示例性实施例提供一种可从通信网络下载和/或存储在机器可读存储介质上的计算机程序，其包括用于实施如上述示例性实施例所述的电网频率检测方法，和/或用于实施如上述示例性实施例所述的电网频率调节方法的程序代码指令。
虽然已表示和描述了本公开的一些示例性实施例，但本领域技术人员应该理解，在不脱离由权利要求及其等同物限定其范围的本公开的原理和精神的情况下，可以对这些实施例进行修改。

Claims (18)

  1. 一种电网频率检测方法，其中，包括：
    将采集的并网点的三相电压变换为两相电压；
    基于特定频率的相角对所述两相电压进行变换，得到待解耦的电压正序分量和电压负序分量；
    基于所述相角对待解耦的电压正序分量和电压负序分量进行解耦，并对解耦后的电压正序分量进行滤波，得到电压正序基波分量；
    基于所述相角对所述电压正序基波分量进行反变换，得到两相静止坐标系下的一组正交电压分量；
    基于所述一组正交电压分量，得到电网相角；
    基于所述电网相角，得到电网频率。
  2. 根据权利要求1所述的电网频率检测方法，其中，所述相角通过对特定角速度进行积分得到；
    其中，所述特定角速度对应的频率为所述特定频率。
  3. 根据权利要求1所述的电网频率检测方法，其中，将采集的并网点的三相电压变换为两相电压的步骤包括：
    对采集的并网点的三相电压进行带通滤波，其中，所述带通滤波的中心频率为：电网额定频率或上一电网频率检测周期检测得到的电网频率；
    对带通滤波后的三相电压进行Clark等幅值变换，得到两相电压。
  4. 根据权利要求1所述的电网频率检测方法，其中，
    基于特定频率的相角对所述两相电压进行变换，得到待解耦的电压正序分量和电压负序分量的步骤包括：基于所述相角对所述两相电压进行正负序旋转坐标变换，得到正序旋转坐标系下的待解耦的电压正序分量和负序旋转坐标系下的待解耦的电压负序分量；
    其中，所述电网频率检测方法还包括：对解耦后的电压负序分量进行滤波，得到电压负序基波分量；
    其中，基于所述相角对待解耦的电压正序分量和电压负序分量进行解耦的步骤包括：
    基于所述相角，使用上一电网频率检测周期得到的电压负序基波分量对待解耦的电压正序分量进行交叉反馈解耦，得到解耦后的电压正序分量；
    基于所述相角，使用上一电网频率检测周期得到的电压正序基波分量对待解耦的电压负序分量进行交叉反馈解耦，得到解耦后的电压负序分量；
    其中，所述正序旋转坐标系和所述负序旋转坐标系构成双同步旋转坐标系。
  5. 根据权利要求1所述的电网频率检测方法，其中，对解耦后的电压正序分量进行滤波，得到电压正序基波分量的步骤包括：
    对解耦后的电压正序分量进行带阻滤波和低通滤波，得到电压正序基波分量；
    其中，所述带阻滤波的中心频率为：电网额定频率或上一电网频率检测周期检测得到的电网频率；
    其中，所述特定频率高于所述低通滤波的截止频率。
  6. 根据权利要求1至5中的任意一项所述的电网频率检测方法，其中，基于所述电网相角得到电网频率的步骤包括：
    对所述电网相角进行微分计算，得到第一频率；
    对第一频率进行滤波，得到第二频率；
    基于第二频率，得到所述电网频率。
  7. 根据权利要求6所述的电网频率检测方法，其中，所述电网频率检测方法还包括：
    对第二频率进行微分计算，得到第二频率的变化率；
    对第二频率的变化率进行滤波，得到电网频率变化率。
  8. 根据权利要求7所述的电网频率检测方法，其中，基于第二频率得到所述电网频率的步骤包括：
    将所述电网频率变化率与频率补偿系数的乘积叠加到第二频率，并将叠加后的结果作为所述电网频率。
  9. 一种电网频率调节方法，其中，包括：
    确定并网点的三相电压幅值是否存在扰动；
    当不存在扰动时，根据检测的电网频率和/或电网频率变化率，确定是否满足电网频率调节响应条件；
    当满足所述电网频率调节响应条件时，基于所述电网频率和/或所述电网频率变化率控制风力发电机组的功率，以对电网频率进行调节；
    其中，所述电网频率和/或所述电网频率变化率通过执行如权利要求1至 8中的任意一项所述的电网频率检测方法得到。
  10. 根据权利要求9所述的电网频率调节方法，其中，确定并网点的三相电压幅值是否存在扰动的步骤包括：
    基于解耦后的电压正序分量和对解耦后的电压正序分量进行滤波后得到的电压正序基波分量，确定并网点的三相电压幅值是否存在扰动；
    其中，所述解耦后的电压正序分量和滤波后得到的电压正序基波分量通过执行如权利要求1至8中的任意一项所述的电网频率检测方法得到。
  11. 根据权利要求10所述的电网频率调节方法，其中，基于解耦后的电压正序分量和对解耦后的电压正序分量进行滤波后得到的电压正序基波分量，确定并网点的三相电压幅值是否存在扰动的步骤包括：
    基于解耦后的电压正序分量和滤波后得到的电压正序基波分量，得到解耦后的电压正序分量中的高频信号的模值；
    当所述高频信号的模值大于预设阈值时，确定并网点的三相电压幅值存在扰动。
  12. 根据权利要求9所述的电网频率调节方法，其中，电网频率调节响应条件包括：惯量响应条件和一次调频响应条件；
    其中，根据检测的电网频率和/或电网频率变化率，确定是否满足电网频率调节响应条件的步骤包括：根据所述电网频率及所述电网频率变化率，确定是否满足惯量响应条件；根据所述电网频率，确定是否满足一次调频响应条件；
    其中，当满足所述电网频率调节响应条件时，基于所述电网频率和/或所述电网频率变化率控制风力发电机组的功率，以对电网频率进行调节的步骤包括：当惯量响应条件和一次调频响应条件同时满足时，优先通过基于所述电网频率变化率控制风力发电机组的功率，来进行惯量响应。
  13. 根据权利要求9所述的电网频率调节方法，其中，基于所述电网频率和/或所述电网频率变化率控制风力发电机组的功率，以对电网频率进行调节的步骤包括：
    基于所述电网频率和/或所述电网频率变化率，确定风力发电机组的有功增量目标值；
    基于有功增量目标值及发电机的转速，计算发电机的附加转矩值；
    基于发电机的转矩值和附加转矩值，计算发电机的目标转矩值；
    基于发电机的目标转矩值控制发电机的转矩，以控制风力发电机组的功率。
  14. 根据权利要求9所述的电网频率调节方法，其中，基于所述电网频率和/或所述电网频率变化率控制风力发电机组的功率，以对电网频率进行调节的步骤包括：
    基于所述电网频率和/或所述电网频率变化率，确定风力发电机组的有功增量目标值；
    基于有功增量目标值确定在多个控制周期中的每个控制周期需要调节的有功增量值，其中，所述多个控制周期包括当前控制周期及其后续控制周期；
    按照每个控制周期需要调节的有功增量值，控制风力发电机组的功率；
    其中，所述多个控制周期需要调节的有功增量值的总和为所述有功增量目标值。
  15. 一种电网频率检测装置，其中，包括：
    两相电压获取单元，被配置为将采集的并网点的三相电压变换为两相电压；
    变换单元，被配置为基于特定频率的相角对所述两相电压进行变换，得到待解耦的电压正序分量和电压负序分量；
    解耦滤波单元，被配置为基于所述相角对待解耦的电压正序分量和电压负序分量进行解耦，并对解耦后的电压正序分量进行滤波，得到电压正序基波分量；
    反变换单元，被配置为基于所述相角对所述电压正序基波分量进行反变换，得到两相静止坐标系下的一组正交电压分量；
    电网相角获取单元，被配置为基于所述一组正交电压分量，得到电网相角；
    电网频率获取单元，被配置为基于所述电网相角，得到电网频率。
  16. 一种电网频率调节装置，其中，包括：
    电压扰动判断单元，被配置为确定并网点的三相电压幅值是否存在扰动；
    响应条件判断单元，被配置为当不存在扰动时，根据检测的电网频率和/或电网频率变化率，确定是否满足电网频率调节响应条件；
    电网频率调节单元，被配置为当满足所述电网频率调节响应条件时，基于所述电网频率和/或所述电网频率变化率控制风力发电机组的功率，以对电 网频率进行调节；
    其中，所述电网频率和/或所述电网频率变化率通过如权利要求15所述的电网频率检测装置得到。
  17. 一种存储有计算机程序的计算机可读存储介质，其中，当所述计算机程序被处理器执行时，促使所述处理器执行如权利要求1至8中的任意一项所述的电网频率检测方法和/或如权利要求9至14中的任意一项所述的电网频率调节方法。
  18. 一种电子设备，其中，所述电子设备包括：
    处理器；
    存储器，存储有计算机程序，当所述计算机程序被处理器执行时，促使所述处理器执行如权利要求1至8中的任意一项所述的电网频率检测方法和/或如权利要求9至14中的任意一项所述的电网频率调节方法。
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