Wind and light storage micro-grid system and method

Abstract

The invention provides a wind and light storage micro-grid system and method. Measurement data of each measurement channel are collected through a synchronous phasor measurement device; selecting a plurality of dominant directions according to the degree of unbalance among all the measurement data, and determining a voltage characteristic curve of a plurality of alternating voltages based on the distribution characteristics of all the measurement data in each dominant direction; screening out a plurality of mode components related to subsynchronous oscillation from all the voltage characteristic curves according to the characteristic operator of resonance interference in each voltage characteristic curve; the instantaneous frequency of the voltage in each measurement channel is tracked through all the mode components, and then oscillation characteristic parameters are obtained; and when the oscillation characteristic parameter exceeds a preset oscillation threshold value, controlling flexible alternating current power transmission equipment in the wind-solar-storage micro-grid to support the voltage of the wind-solar-storage micro-grid. By adopting the scheme provided by the invention, global monitoring can be performed on the subsynchronous oscillation of the wind-solar-storage micro-grid system, so that the operation safety of the wind-solar-storage micro-grid is improved.

Description

Technical Field

[0001] The present application relates to the field of power grid control technology, and more specifically, to a wind, solar and energy storage microgrid system and method. Background Art

[0002] Grid control refers to ensuring the safety, stability and economy of the power grid under various operating conditions and meeting users' demand for power supply by regulating and optimizing the operating status of power generation, transmission, distribution and load in the power system. The goal of grid control is to achieve power balance (real-time matching of power generation and load), ensure power quality (such as stability of indicators such as frequency and voltage), and ensure efficient operation of the system (such as reducing transmission losses and improving the utilization rate of new energy).

[0003] During the operation of wind, solar and energy storage microgrids, subsynchronous oscillations may exist, which refers to oscillations of certain specific frequencies in the power system, and the frequencies of these oscillations are lower than the basic frequency of the system (50Hz or 60Hz). These oscillations may be caused by the dynamic response of components such as wind turbines, solar inverters, and energy storage systems, especially when multiple renewable energy sources (wind energy, solar energy) and energy storage systems are connected to the grid. Subsynchronous oscillations are one of the stability issues of the power system. If not controlled, it may lead to a decrease in the stability of the power grid and even cause equipment damage or power failures.

[0004] In the prior art, subsynchronous oscillation phenomena are usually monitored by a single sampling point in a wind, solar, and storage microgrid, which makes it difficult to take into account the global subsynchronous oscillation characteristics of the wind, solar, and storage microgrid system. In addition, due to the complexity of the wind, solar, and storage microgrid, there is information imbalance in the monitoring of subsynchronous oscillation phenomena at different sampling points. The above problems will lead to errors in the identification of subsynchronous oscillation phenomena, thereby endangering the operation safety of the wind, solar, and storage microgrid. Therefore, how to globally monitor the subsynchronous oscillations of the wind, solar, and storage microgrid system and thereby improve the operation safety of the wind, solar, and storage microgrid has become a difficult problem faced by the industry. Summary of the invention

[0005] The present application provides a wind-solar-storage microgrid system and method, which can globally monitor the subsynchronous oscillation of the wind-solar-storage microgrid system, thereby improving the safety of the wind-solar-storage microgrid operation.

[0006] In a first aspect, the present application provides a voltage support method, comprising: A plurality of measurement channels are set in the wind-solar-storage microgrid, and each measurement channel in the operation process of the wind-solar-storage microgrid is monitored in real time by the synchronous phasor measurement device to obtain measurement data of each measurement channel; Select multiple dominant directions of electric energy change in the wind-solar-storage microgrid according to the imbalance between all measured data, determine the distribution characteristics of all measured data in each dominant direction, and decompose all measured data into voltage characteristic curves of multiple alternating voltages based on the distribution characteristics; The characteristic operators of the resonant disturbance in the wind-solar-storage microgrid are identified from each voltage characteristic curve, and multiple mode components related to subsynchronous oscillation are screened out from all voltage characteristic curves according to all the characteristic operators; Each mode component is resolved into a modulation signal in the complex domain, and the instantaneous frequency of the voltage in each measurement channel is tracked through all the modulation signals to obtain the oscillation characteristic parameters; When the oscillation characteristic parameter exceeds a preset threshold, the flexible AC power transmission equipment in the wind, solar, and storage microgrid is controlled to compensate for the impedance characteristics of the wind, solar, and storage microgrid, thereby supporting the voltage of the wind, solar, and storage microgrid.

[0007] In some embodiments, selecting multiple dominant directions of power change in the wind-solar-storage microgrid according to the imbalance between all measured data specifically includes: Convert all measurement data into measurement matrix; Determine the measurement matrix to determine the imbalance between all measurement data; Setting a plurality of candidate directions in the hypersphere according to the total number of measurement data; According to the imbalance degree, multiple dominant directions of electric energy change in the wind-solar-storage microgrid are selected from all candidate directions.

[0008] In some embodiments, determining the distribution characteristics of all measurement data in each dominant direction may be implemented by the following steps: For each dominant direction, all measurement data are projected onto the dominant direction to obtain a projection vector; The distribution characteristics of all the measurement data in the dominant direction are determined according to the projection vector, and then the distribution characteristics of all the measurement data in each dominant direction are obtained.

[0009] In some embodiments, the characteristic operator for identifying the resonant interference in the wind-solar-storage microgrid from each voltage characteristic curve specifically includes: For each measurement data, determining the fluctuation energy value of each voltage characteristic curve corresponding to the measurement data; According to all the fluctuating energy values, the characteristic operator of the resonant interference in the wind-solar-storage microgrid corresponding to each voltage characteristic curve is determined, and then the characteristic operator of the resonant interference in the wind-solar-storage microgrid corresponding to each voltage characteristic curve in each measured data is obtained.

[0010] In some embodiments, screening out multiple mode components related to subsynchronous oscillations from all voltage characteristic curves according to all characteristic operators means treating all voltage characteristic curves corresponding to characteristic operators greater than a preset resonance threshold as mode components related to subsynchronous oscillations, thereby obtaining multiple mode components related to subsynchronous oscillations.

[0011] In some embodiments, the instantaneous frequency of the voltage in each measurement channel is tracked by all modulation signals, and the oscillation characteristic parameters are obtained, specifically including: Determining the instantaneous frequency function and the instantaneous damping ratio function of each modulation signal; For each measurement channel, the tracking frequency and the tracking damping ratio of the subsynchronous oscillation in the measurement channel are determined according to all instantaneous frequency functions and instantaneous damping ratio functions corresponding to the measurement channel, thereby obtaining the tracking frequency and the tracking damping ratio of the subsynchronous oscillation in each measurement channel; Determine the oscillation frequency of subsynchronous oscillation in the wind-solar-storage microgrid based on all tracking frequencies; The oscillation damping ratio of the subsynchronous oscillation in the wind-solar-storage microgrid is determined according to all tracking damping ratios, and the oscillation frequency and the oscillation damping ratio are used as oscillation characteristic parameters.

[0012] In some embodiments, the wind-solar-storage microgrid is a wind-solar-storage complementary microgrid.

[0013] In a second aspect, the present application provides a wind-solar-storage microgrid system, the wind-solar-storage microgrid system includes a voltage support unit, and the voltage support unit includes: The acquisition module is used to instruct the synchronized phasor measurement device to perform real-time monitoring on each measurement channel during the operation of the wind-solar-storage microgrid after multiple measurement channels are set in the wind-solar-storage microgrid to obtain measurement data of each measurement channel; A processing module, used to select multiple dominant directions of electric energy change in the wind-solar-storage microgrid according to the imbalance between all the measured data, determine the distribution characteristics of all the measured data in each dominant direction, and decompose all the measured data into voltage characteristic curves of multiple alternating voltages based on the distribution characteristics; The processing module is also used to identify characteristic operators of resonant interference in the wind-solar-storage microgrid from each voltage characteristic curve, and screen out multiple mode components related to subsynchronous oscillation from all voltage characteristic curves according to all characteristic operators; The processing module is also used to resolve each mode component into a modulation signal in the complex domain, and track the instantaneous frequency of the voltage in each measurement channel through all the modulation signals, thereby obtaining the oscillation characteristic parameters; The execution module is used to control the flexible AC transmission equipment in the wind-solar-storage microgrid to compensate for the impedance characteristics of the wind-solar-storage microgrid when the oscillation characteristic parameter exceeds a preset threshold, thereby supporting the voltage of the wind-solar-storage microgrid.

[0014] In a third aspect, the present application provides a computer device, comprising a memory and a processor, wherein the memory stores codes, and the processor is configured to obtain the codes and execute the above-mentioned voltage support method.

[0015] In a fourth aspect, the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and the computer program implements the above-mentioned voltage support method when executed by a processor.

[0016] The technical solution provided by the embodiments disclosed in this application has the following beneficial effects: In the wind-solar-storage microgrid system and method provided by the present application, firstly, a plurality of measurement channels are set in the wind-solar-storage microgrid, and each measurement channel in the operation process of the wind-solar-storage microgrid is monitored in real time by the synchronous phasor measurement device to obtain the measurement data of each measurement channel; according to the imbalance between all the measurement data, a plurality of dominant directions of electric energy change in the wind-solar-storage microgrid are selected, the distribution characteristics of all the measurement data in each dominant direction are determined, and all the measurement data are decomposed into a plurality of voltage characteristic curves of alternating voltages based on all the distribution characteristics; from each voltage characteristic curve, the voltage characteristic curve is obtained. Multiple characteristic operators of resonant interference in the wind-solar-storage microgrid are identified in the line, and multiple mode components related to subsynchronous oscillations are screened out from all voltage characteristic curves according to all characteristic operators; each mode component is parsed into a modulation signal in the complex domain, and the instantaneous frequency of the voltage in each measurement channel is tracked through all modulation signals, so as to obtain the oscillation characteristic parameters; when the oscillation characteristic parameters exceed the preset oscillation threshold, the flexible AC transmission equipment in the wind-solar-storage microgrid is controlled to compensate for the impedance characteristics of the wind-solar-storage microgrid, so as to support the voltage of the wind-solar-storage microgrid.

[0017] It can be seen that in this application, multiple dominant directions of power changes in the wind-solar-storage microgrid are selected based on the imbalance degree among all measurement data, and the distribution characteristics of all measurement data in each dominant direction are determined. That is, the structure of the entire wind-solar-storage microgrid and the characteristics of power changes during operation are determined. Furthermore, all measurement data are decomposed into voltage characteristic curves of various alternating voltages based on the distribution characteristics, that is, the AC components with different frequencies and the components of subsynchronous oscillation in the wind-solar-storage microgrid are separated. Subsequently, multiple characteristic operators of resonance interference in the wind-solar-storage microgrid are identified from each voltage characteristic curve, that is, the proportion of the subsynchronous oscillation component in each voltage characteristic curve is determined. The voltage characteristic curve with a large characteristic operator is the mode component related to subsynchronous oscillation. Finally, through signal processing means, the mode component is analyzed into the complex domain and the instantaneous frequency of the voltage is tracked, and then the subsynchronous oscillation in the wind-solar-storage microgrid is accurately identified (that is, when the oscillation characteristic parameter exceeds the preset oscillation threshold, subsynchronous oscillation occurs), and when subsynchronous oscillation occurs, the flexible AC transmission equipment is controlled to compensate for the impedance characteristics to avoid the harm caused by the subsynchronous oscillation phenomenon to the wind-solar-storage microgrid system. In summary, this application can globally monitor the subsynchronous oscillation of the wind-solar-storage microgrid system, thereby improving the operation safety of the wind-solar-storage microgrid. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is an exemplary flowchart of a voltage support method according to some embodiments of the present application; Figure 2 is an exemplary flowchart of determining a dominant direction according to some embodiments of the present application; Figure 3 is a classification schematic diagram of a flexible AC transmission device according to some embodiments of the present application; Figure 4 is a schematic diagram of the structure of a voltage support unit according to some embodiments of the present application; Figure 5 is a schematic diagram of the structure of a computer device for implementing the voltage support method according to some embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] To better understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0020] Refer to Figure 1 , which is an exemplary flowchart of a voltage support method according to some embodiments of the present application. The voltage support method 100 mainly includes the following steps: In step 101, a plurality of measurement channels are set in the wind-solar-storage microgrid, and each measurement channel in the operation process of the wind-solar-storage microgrid is monitored in real time by the synchronous phasor measurement device to obtain measurement data of each measurement channel.

[0021] The wind, solar and storage microgrid described in the present application may be a wind, solar and storage complementary microgrid, and may also be other types of wind, solar and storage microgrids when implemented, which is not specifically limited here. In addition, in the present application, multiple measurement channels are set in the wind, solar and storage microgrid, which can be implemented in the following manner, namely: measurement channels are set at all key nodes of the wind, solar and storage microgrid, wherein the key nodes include: electrical connection points near substations, distribution networks, wind farms and photovoltaic power generation units. In other embodiments, the key nodes may also include other electrical nodes in the wind, solar and storage microgrid that need to be monitored, which is not limited here.

[0022] It should be noted that the measurement channel in this application refers to the channel used for data collection and transmission in the wind, solar and storage microgrid. The channel includes sensors, signal modulation equipment and signal transmission equipment. The measurement channel is used to collect physical quantities in the wind, solar and storage microgrid and convert them into electrical signals, and transmit the electrical signals to the control center of the wind, solar and storage microgrid.

[0023] In specific implementation, each measurement channel in the operation process of the wind-solar-storage microgrid is monitored in real time by the synchronous phasor measurement device, and the measurement data of each measurement channel can be obtained in the following way, namely: for each measurement channel, the voltage value of the measurement channel is collected by the phasor measurement unit at every preset sampling interval, all the collected voltage values ​​are sorted according to the order of sampling, and the obtained sequence is used as the measurement data of the measurement channel, thereby obtaining the measurement data of each measurement channel, wherein the sampling interval can be preset according to actual needs. For example, in the present application, the sampling interval can be preset to 0.5s.

[0024] It should be noted that the measurement data in the present application refers to the voltage data in the wind, solar and energy storage microgrid. In other embodiments, the measurement data may also include data of other electrical parameters in the wind, solar and energy storage microgrid, such as current data and phase angle data, etc., which are not limited here.

[0025] It should be noted that the sampling moments of all voltage values ​​in each measurement data in the present application correspond one to one (ie, the first voltage value in each measurement data is collected at the same sampling moment, and the sampling intervals of each measurement data are the same when collected).

[0026] In step 102, multiple dominant directions of electric energy change in the wind-solar-storage microgrid are selected according to the imbalance between all measured data, the distribution characteristics of all measured data in each dominant direction are determined, and all measured data are decomposed into voltage characteristic curves of multiple alternating voltages based on all distribution characteristics.

[0027] In some embodiments, reference Figure 2 , which is an exemplary flow chart of determining the dominant direction according to some embodiments of the present application. In the present application, selecting multiple dominant directions of electric energy change in the wind-solar-storage microgrid according to the imbalance between all measured data can be implemented by the following steps: In step 1021, all measurement data are converted into a measurement matrix; In step 1022, the measurement matrix is ​​determined to determine the imbalance between all the measurement data; In step 1023, a plurality of candidate directions are set in the hypersphere according to the total number of measurement data; In step 1024, multiple dominant directions of electric energy change in the wind-solar-storage microgrid are selected from all candidate directions according to the imbalance degree.

[0028] In specific implementation, converting all measurement data into a measurement matrix can be achieved in the following manner, namely: first, all measurement channels are numbered (i.e., a measurement channel is randomly selected and marked as 1, and then a measurement channel is randomly selected from the remaining measurement channels and marked as 2, and all the remaining measurement channels are numbered in turn), and then, the measurement data corresponding to the measurement channels are arranged in rows in the order of the numbers (i.e., the measurement data corresponding to the measurement channel labeled i is used as the i-th row data in the matrix), and finally, the obtained matrix is ​​used as the measurement matrix.

[0029] It should be noted that the measurement matrix in this application refers to a matrix composed of all measurement data.

[0030] In specific implementation, determining the imbalance between all measurement data using the measurement matrix can be achieved in the following manner, namely: first, calculating the covariance matrix of the measurement matrix, then calculating all eigenvalues ​​and all eigenvectors of the covariance matrix, taking the largest eigenvalue as the imbalance between all measurement data, and taking the eigenvector corresponding to the imbalance as the direction of the imbalance between all measurement data.

[0031] It should be noted that the imbalance degree in the present application is a parameter for measuring the degree of difference between different measurement data. The greater the imbalance degree, the greater the difference between different measurement data, and the smaller the imbalance degree, the smaller the difference between different measurement data.

[0032] In specific implementation, setting multiple candidate directions in a hypersphere according to the total number of measurement data can be achieved in the following manner: first, the total number L of measurement channels is counted, and then, sampling is performed in a hypersphere of dimension (L-1) by the Hammersley sampling method in the prior art to obtain multiple L-dimensional direction vectors, and all the obtained direction vectors are used as candidate vectors.

[0033] It should be noted that the candidate vector in this application is a vector representing the direction of change of electric energy in the wind, solar and storage microgrid.

[0034] In specific implementation, selecting multiple dominant directions of electric energy change in the wind-solar-storage microgrid from all candidate directions according to the imbalance can be achieved in the following manner, namely: first, obtaining the vector A corresponding to the direction of the imbalance between all measured data, and setting a vector B with the same length as the direction completely opposite to the direction; then, calculating the mutual correlation coefficient between each candidate vector and vector A, and taking the candidate vector with the largest mutual correlation coefficient as vector C; and calculating the mutual correlation coefficient between each candidate vector and vector B, and taking the candidate vector with the largest mutual correlation coefficient as vector D; then, adding vector A and vector C to obtain vector E, and then dividing vector E by the length of vector E, and taking the obtained vector as a dominant direction; finally, adding vector B and vector D to obtain vector F, and then dividing vector F by the length of vector F, and taking the obtained vector as another dominant direction.

[0035] It should be noted that the dominant direction in this application refers to the main direction of change of electric energy in the wind, solar and storage microgrid.

[0036] In some embodiments, determining the distribution characteristics of all measurement data in each dominant direction may be achieved by using the following steps: For each dominant direction, all measurement data are projected onto the dominant direction to obtain a projection vector; The distribution characteristics of all the measurement data in the dominant direction are determined according to the projection vector, and then the distribution characteristics of all the measurement data in each dominant direction are obtained.

[0037] In specific implementation, all measurement data are projected to the dominant direction, and the projection vector can be obtained in the following manner, namely: first, the measurement matrix corresponding to all measurement data is obtained, and then, for each column of data in the measurement matrix, the dot product of each column of data and the vector of the dominant direction is performed to obtain the value Z, and then the value Z of each column of data in the measurement matrix is ​​obtained, and then all the values ​​Z are arranged according to the order of the corresponding column data in the measurement matrix, and the obtained sequence is used as the projection vector of the dominant direction.

[0038] It should be noted that the projection vector in this application is a vector that reflects the change of electric energy in the wind, solar and energy storage microgrid in the dominant direction.

[0039] In specific implementation, the distribution characteristics of all measurement data in the dominant direction can be determined based on the projection vector in the following manner, namely: first, all local maxima in the projection vector are extracted, and then, all local maxima are fitted into a curve by the Lagrange interpolation method in the prior art, and the obtained curve is used as the distribution characteristics of all measurement data in the dominant direction.

[0040] It should be noted that the distribution characteristics in this application are curves that describe the changes in the dominant direction of electric energy in the wind, solar and storage microgrid.

[0041] In some embodiments, decomposing all measured data into voltage characteristic curves of multiple alternating voltages based on all distribution characteristics can be achieved by using the following steps: Determine uniform distribution characteristics based on all distribution characteristics; For each measurement data, determining a voltage characteristic curve and a residual component of the measurement data according to the uniform distribution characteristics; determining a fluctuation index of the residual component; When the fluctuation index is greater than zero, the residual component is used as new measurement data, and the steps of determining the voltage characteristic curve and the residual component based on all the measurement data are repeated to obtain a new voltage characteristic curve and a new residual component until the fluctuation index is equal to zero, thereby obtaining multiple voltage characteristic curves, and further obtaining multiple voltage characteristic curves for each measurement data.

[0042] In specific implementation, determining the uniform distribution feature according to all the distribution features can be achieved in the following manner, that is, the curves corresponding to all the distribution features can be added together and then divided by the total number of the distribution features, and the obtained curve is used as the uniform distribution feature.

[0043] It should be noted that the uniform distribution feature in the present application is a curve obtained by averaging the distribution features in each dominant direction.

[0044] In a specific implementation, determining the voltage characteristic curve and residual component of the measured data according to the uniform distribution characteristics can be achieved in the following manner, namely: first, discretizing the curve of the uniform distribution characteristics into a discrete sequence with the same length as the measured data, then subtracting the discrete sequence from the measured data, taking the obtained sequence as the residual component, and taking the discrete sequence as the voltage characteristic curve, wherein discretizing the curve of the uniform distribution characteristics into a discrete sequence with the same length as the measured data means sampling the curve of the uniform distribution characteristics at the same sampling interval as that when the measured data is collected, and taking the obtained sequence as the discrete sequence.

[0045] It should be noted that the voltage characteristic curve in this application is a sequence that reflects the voltage change characteristics in the wind, solar and storage microgrid.

[0046] In addition, it should be noted that the residual component in the present application is the residual measurement data after removing the voltage characteristic curve.

[0047] In specific implementation, determining the fluctuation index of the residual component can be achieved in the following manner, namely: first, forward differencing the residual component, then counting the number of positive numbers and the number of negative numbers in the sequence after forward differencing, and finally, multiplying the number of positive numbers by the number of negative numbers to obtain a value as the fluctuation index of the residual component.

[0048] It should be noted that the fluctuation index in this application is a parameter value indicating the degree of fluctuation of the residual component. The larger the fluctuation index, the greater the degree of fluctuation of the residual component, and the smaller the fluctuation index, the smaller the degree of fluctuation of the residual component. The fluctuation index is a value greater than or equal to zero.

[0049] It should be noted that the steps of determining the voltage characteristic curve and the residual component based on all the measured data in the present application include: selecting multiple dominant directions of electric energy changes in the wind, solar and storage microgrid according to the imbalance between all the measured data, determining the distribution characteristics of all the measured data in each dominant direction, and for each measured data, determining the voltage characteristic curve and the residual component of the measured data according to the uniform distribution characteristics.

[0050] In step 103, characteristic operators of resonant interference in the wind-solar-storage microgrid are identified from each voltage characteristic curve, and multiple mode components related to subsynchronous oscillation are screened out from all voltage characteristic curves based on all characteristic operators.

[0051] In some embodiments, the characteristic operator for identifying the resonant interference in the wind-solar-storage microgrid from each voltage characteristic curve can be implemented by the following steps: For each measurement data, determining the fluctuation energy value of each voltage characteristic curve corresponding to the measurement data; According to all the fluctuating energy values, the characteristic operator of the resonant interference in the wind-solar-storage microgrid corresponding to each voltage characteristic curve is determined, and then the characteristic operator of the resonant interference in the wind-solar-storage microgrid corresponding to each voltage characteristic curve in each measured data is obtained.

[0052] In specific implementation, determining the fluctuation energy value of each voltage characteristic curve corresponding to the measured data can be achieved in the following manner, namely: for each voltage characteristic curve, first, calculate the product x of the n+1th value and the n-1th value in the sequence of the voltage characteristic curve, then subtract x from the square of the nth value in the sequence of the voltage characteristic curve, and use the obtained value as the process quantity of the nth value, then calculate the sum of the process quantities of all values ​​in the sequence of the voltage characteristic curve, and use the obtained sum as the fluctuation energy value of the voltage characteristic curve, thereby obtaining the fluctuation energy value of each voltage characteristic curve.

[0053] It should be noted that the fluctuation energy value in the present application is a parameter value representing the voltage fluctuation amplitude at the corresponding moment in the voltage characteristic curve. The larger the fluctuation energy value, the larger the voltage fluctuation amplitude at the corresponding moment in the voltage characteristic curve. The smaller the fluctuation energy value, the smaller the voltage fluctuation amplitude at the corresponding moment in the voltage characteristic curve.

[0054] In specific implementation, the characteristic operator of the resonant interference in the wind, solar and storage microgrid corresponding to each voltage characteristic curve is determined according to all the fluctuating energy values. This can be achieved in the following way: first, the sum of all the fluctuating energy values ​​is calculated. Then, for the voltage characteristic curve, the fluctuating energy value corresponding to the voltage characteristic curve is divided by the sum of all the fluctuating energy values. The obtained value is used as the characteristic operator of the resonant interference in the wind, solar and storage microgrid corresponding to the voltage characteristic curve, thereby obtaining the characteristic operator of the resonant interference in the wind, solar and storage microgrid corresponding to each voltage characteristic curve.

[0055] It should be noted that the characteristic operator in this application is a parameter value that indicates how much resonant interference characteristics of the wind, solar and storage microgrid are contained in the voltage characteristic curve. The larger the characteristic operator, the more resonant interference characteristics of the wind, solar and storage microgrid are contained in the voltage characteristic curve. The smaller the characteristic operator, the fewer resonant interference characteristics of the wind, solar and storage microgrid are contained in the voltage characteristic curve. The resonant interference is caused by energy exchange between the generator set and the power grid at multiple sub-synchronous frequencies.

[0056] In some embodiments, screening out multiple mode components related to subsynchronous oscillations from all voltage characteristic curves according to all characteristic operators means treating all voltage characteristic curves corresponding to characteristic operators greater than a preset resonance threshold as mode components related to subsynchronous oscillations, thereby obtaining multiple mode components related to subsynchronous oscillations.

[0057] It should be noted that the resonance threshold in the present application is usually preset to any value between zero and one. For example, the resonance threshold can be preset to 0.5 according to actual needs. Those skilled in the art know that the resonance threshold can be preset to other values ​​between zero and one according to actual needs, which all fall within the protection scope of the present invention and will not be repeated here.

[0058] In step 104, each mode component is resolved into a modulation signal in the complex domain, and the instantaneous frequency of the voltage in each measurement channel is tracked through all the modulation signals to obtain the oscillation characteristic parameters.

[0059] In some embodiments, parsing each mode component into a modulated signal in the complex domain means parsing each mode component into a modulated signal in the complex domain by using the Hilbert-Huang transform in the prior art. In other embodiments, other prior arts may also be used to parse each mode component into a modulated signal in the complex domain, which is not limited here.

[0060] It should be noted that the modulated signal in this application is a function of the mode component after analysis.

[0061] In some embodiments, the instantaneous frequency of the voltage in each measurement channel is tracked by all modulation signals, and then the oscillation characteristic parameters are obtained by the following steps: Determining the instantaneous frequency function and the instantaneous damping ratio function of each modulation signal; For each measurement channel, the tracking frequency and the tracking damping ratio of the subsynchronous oscillation in the measurement channel are determined according to all instantaneous frequency functions and instantaneous damping ratio functions corresponding to the measurement channel, thereby obtaining the tracking frequency and the tracking damping ratio of the subsynchronous oscillation in each measurement channel; Determine the oscillation frequency of subsynchronous oscillation in the wind-solar-storage microgrid based on all tracking frequencies; The oscillation damping ratio of the subsynchronous oscillation in the wind-solar-storage microgrid is determined according to all tracking damping ratios, and the oscillation frequency and the oscillation damping ratio are used as oscillation characteristic parameters.

[0062] In specific implementation, the instantaneous frequency function and instantaneous damping ratio function of each modulation signal can be determined in the following manner, that is, for each modulation signal, first, the phase function of the modulation signal is differentiated with respect to the time variable to obtain the function f, and the function f is divided by 2 times the circumference of the circle, and the obtained function is used as the instantaneous frequency function, then, the amplitude function of the modulation signal is differentiated with respect to the time variable to obtain the function h, and finally, as a function of the instantaneous damping ratio.

[0063] It should be noted that the instantaneous frequency function in the present application is a function that describes the instantaneous frequency of the voltage change in the mode component.

[0064] In specific implementation, the tracking frequency and tracking damping ratio of the subsynchronous oscillation in the measurement channel can be determined according to all instantaneous frequency functions and instantaneous damping ratio functions corresponding to the measurement channel. This can be achieved in the following manner: first, the current moment is substituted as the input value of the function into all instantaneous frequency functions and instantaneous damping ratio functions, and the average value of all instantaneous frequency function output values ​​is used as the tracking frequency of the subsynchronous oscillation in the measurement channel, and the average value of all instantaneous damping ratio function output values ​​is used as the tracking damping ratio of the subsynchronous oscillation in the measurement channel.

[0065] It should be noted that the tracking frequency in this application is the frequency of the subsynchronous oscillation in the wind, solar and storage microgrid monitored through a single measurement channel, and the tracking damping ratio is the damping ratio of the subsynchronous oscillation in the wind, solar and storage microgrid monitored through a single measurement channel.

[0066] It should be noted that the oscillation frequency in the present application refers to the frequency of the subsynchronous oscillation in the wind, solar and storage microgrid. As a preferred embodiment, the oscillation frequency of the subsynchronous oscillation in the wind, solar and storage microgrid is determined according to all tracking frequencies in the present application. This can be achieved in the following way, namely: the average value of all tracking damping ratios is used as the oscillation frequency of the subsynchronous oscillation in the wind, solar and storage microgrid.

[0067] It should be noted that the oscillation damping ratio in the present application refers to the damping ratio of subsynchronous oscillations in a wind, solar, and storage microgrid. As a preferred embodiment, the oscillation damping ratio of subsynchronous oscillations in a wind, solar, and storage microgrid is determined according to all tracking damping ratios in the present application. This can be achieved in the following way, namely: first, the average value of all tracking damping ratios is used as the oscillation damping ratio of subsynchronous oscillations in the wind, solar, and storage microgrid.

[0068] In step 105, when the oscillation characteristic parameter exceeds a preset oscillation threshold, the flexible AC transmission equipment in the wind, solar, and storage microgrid is controlled to compensate for the impedance characteristics of the wind, solar, and storage microgrid, thereby supporting the voltage of the wind, solar, and storage microgrid.

[0069] It should be noted that the oscillation threshold in the present application includes an oscillation frequency threshold and an oscillation damping ratio threshold, wherein the oscillation frequency threshold and the oscillation damping ratio threshold are both preset values ​​according to actual needs. For example, in the present application, the oscillation frequency threshold can be preset to 50 Hz, and the oscillation damping ratio threshold can be preset to 3%. Those skilled in the art know that the oscillation frequency threshold and the oscillation damping ratio threshold can be preset to other values ​​according to actual needs, which all fall within the protection scope of the present invention and will not be repeated here.

[0070] In addition, it should be noted that the oscillation characteristic parameter described in the present application exceeds the preset oscillation threshold value, which means that the oscillation frequency in the oscillation characteristic parameter is greater than the oscillation frequency threshold value in the oscillation threshold value, and the oscillation damping ratio in the oscillation characteristic parameter is less than the oscillation damping ratio threshold value in the oscillation threshold value.

[0071] In specific implementation, controlling the flexible AC transmission equipment in the wind, solar and storage microgrid to compensate for the impedance characteristics of the wind, solar and storage microgrid, and then supporting the voltage of the wind, solar and storage microgrid can be achieved in the following way, namely: the oscillation characteristic parameters can be input into the grid-connected simulation model of the doubly fed wind turbine containing the energy storage battery (for example, the grid-connected simulation model of the doubly fed wind turbine disclosed in the document "Energy Storage Battery Control Strategy for Suppressing Subsynchronous Oscillations in Wind Farms"), and according to the output results, the flexible AC transmission equipment is controlled to compensate for the impedance characteristics of the wind, solar and storage microgrid, and then support the voltage of the wind, solar and storage microgrid. In other embodiments, other existing technologies can also be used to control the flexible AC transmission equipment in the wind, solar and storage microgrid to compensate for the impedance characteristics of the wind, solar and storage microgrid, and then support the voltage of the wind, solar and storage microgrid, which is not limited here.

[0072] In some embodiments, reference Figure 3 , which is a classification diagram of flexible AC power transmission equipment shown in some embodiments of the present application, and is specifically described as follows: Flexible AC power transmission equipment can be divided into series compensation equipment and parallel compensation equipment, wherein the series compensation equipment includes a static synchronous series compensator and a controllable series capacitor filter, and the parallel compensation equipment includes a static VAR compensator and a static synchronous compensator. In other embodiments, the flexible AC power transmission equipment also includes other power equipment, which is not limited here.

[0073] In addition, in another aspect of the present application, in some embodiments, the present application provides a wind-solar-storage microgrid system, the wind-solar-storage microgrid system includes a voltage support unit, reference Figure 4 , which is a schematic diagram of the structure of a voltage support unit according to some embodiments of the present application, the voltage support unit 400 includes: a collection module 401, a processing module 402 and an execution module 403, which are described as follows: The acquisition module 401 in the present application is mainly used to instruct the synchronized phasor measurement device to perform real-time monitoring on each measurement channel during the operation of the wind-solar-storage microgrid after multiple measurement channels are set in the wind-solar-storage microgrid to obtain measurement data of each measurement channel; Processing module 402, in the present application, the processing module 402 is mainly used to select multiple dominant directions of electric energy change in the wind-solar-storage microgrid according to the imbalance between all the measured data, determine the distribution characteristics of all the measured data in each dominant direction, and decompose all the measured data into voltage characteristic curves of multiple alternating voltages based on all the distribution characteristics; It should be noted that the processing module 402 in the present application is also used to identify multiple characteristic operators of resonant interference in the wind-solar-storage microgrid from each voltage characteristic curve, and screen out multiple mode components related to subsynchronous oscillation from all voltage characteristic curves according to all characteristic operators; It should be noted that the processing module 402 in the present application is also used to resolve each mode component into a modulation signal in the complex domain, and track the instantaneous frequency of the voltage in each measurement channel through all the modulation signals, thereby obtaining the oscillation characteristic parameters; Execution module 403. In the present application, execution module 403 is mainly used to control the flexible AC transmission equipment in the wind, solar and storage microgrid to compensate for the impedance characteristics of the wind, solar and storage microgrid when the oscillation characteristic parameters exceed the preset oscillation threshold, thereby supporting the voltage of the wind, solar and storage microgrid.

[0074] In addition, the present application also provides a computer device, which includes a memory and a processor, wherein the memory stores codes, and the processor is configured to obtain the codes and execute the above-mentioned voltage support method.

[0075] In some embodiments, reference Figure 5 , which is a schematic diagram of the structure of a computer device for implementing a voltage support method according to some embodiments of the present application. The voltage support method in the above embodiment can be Figure 5 The computer device 500 shown in the figure is implemented, and the computer device 500 includes at least one processor 501, a communication bus 502, a memory 503 and at least one communication interface 504.

[0076] The processor 501 may be a general-purpose central processing unit (CPU) or an application-specific integrated circuit (ASIC).

[0077] The communication bus 502 may be used to transmit information between the above-mentioned components.

[0078] The memory 503 may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, an optical disc storage (including a compressed optical disc, a laser disc, an optical disc, a digital versatile disc, a Blu-ray disc, etc.), a magnetic disk or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer, but is not limited thereto. The memory 503 may exist independently and be connected to the processor 501 via the communication bus 502. The memory 503 may also be integrated with the processor 501.

[0079] The memory 503 is used to store the program code for executing the solution of the present application, and the execution is controlled by the processor 501. The processor 501 is used to execute the program code stored in the memory 503. The program code may include one or more software modules. The voltage support method in the above embodiment can be implemented by the processor 501 and one or more software modules in the program code in the memory 503.

[0080] The communication interface 504 uses any transceiver or other device for communicating with other devices or communication networks, such as Ethernet, radio access network (RAN), wireless local area networks (WLAN), etc.

[0081] In a specific implementation, as an embodiment, a computer device may include multiple processors, each of which may be a single-CPU processor or a multi-CPU processor. The processor here may refer to one or more devices, circuits, and / or processing cores for processing data (e.g., computer program instructions).

[0082] The above-mentioned computer device may be a general-purpose computer device or a special-purpose computer device. In a specific implementation, the computer device may be a desktop computer, a portable computer, a network server, a personal digital assistant (PDA), a mobile phone, a tablet computer, a wireless terminal device, a communication device or an embedded device. The embodiment of the present application does not limit the type of computer device.

[0083] In addition, the present application also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned voltage support method is implemented.

[0084] In summary, in the wind-solar-storage microgrid system and method disclosed in the embodiment of the present application, first, multiple measurement channels are set in the wind-solar-storage microgrid, and each measurement channel in the operation process of the wind-solar-storage microgrid is monitored in real time by the synchronous phasor measurement device to obtain measurement data of each measurement channel; multiple dominant directions of electric energy change in the wind-solar-storage microgrid are selected according to the imbalance between all measurement data, and the distribution characteristics of all measurement data in each dominant direction are determined, and all measurement data are decomposed into multiple voltage characteristic curves of alternating voltages based on all distribution characteristics; from each electric Multiple characteristic operators of resonant interference in the wind-solar-storage microgrid are identified from the voltage characteristic curve, and multiple mode components related to subsynchronous oscillation are screened out from all voltage characteristic curves according to all the characteristic operators; each mode component is parsed into a modulation signal in the complex domain, and the instantaneous frequency of the voltage in each measurement channel is tracked through all the modulation signals, so as to obtain the oscillation characteristic parameters; when the oscillation characteristic parameters exceed the preset oscillation threshold, the flexible AC transmission equipment in the wind-solar-storage microgrid is controlled to compensate for the impedance characteristics of the wind-solar-storage microgrid, so as to support the voltage of the wind-solar-storage microgrid.

[0085] It can be seen that in this application, multiple dominant directions of electric energy changes in the wind-solar-storage microgrid are selected through the imbalance between all measured data, and the distribution characteristics of all measured data in each dominant direction are determined, that is, the structure of the entire wind-solar-storage microgrid and the characteristics of electric energy changes during operation are determined, and then all measured data are decomposed into voltage characteristic curves of multiple alternating voltages through distribution characteristics, that is, the alternating current components and subsynchronous oscillation components with different frequencies in the wind-solar-storage microgrid are separated, and then, multiple characteristic calculations of resonant interference in the wind-solar-storage microgrid are identified from each voltage characteristic curve. That is, the proportion of subsynchronous oscillation components in each voltage characteristic curve is determined. The voltage characteristic curve with a large characteristic operator is the mode component related to the subsynchronous oscillation. Finally, through signal processing means, the mode component is parsed into the complex domain and the elegant instantaneous frequency is tracked, so as to accurately identify the subsynchronous oscillation in the wind, solar and storage microgrid (that is, when the oscillation characteristic parameter exceeds the preset oscillation threshold, subsynchronous oscillation occurs), and when subsynchronous oscillation occurs, the flexible AC transmission equipment is controlled to compensate for the impedance characteristics to avoid the subsynchronous oscillation phenomenon from causing harm to the wind, solar and storage microgrid system. In summary, the present application can globally monitor the subsynchronous oscillation of the wind, solar and storage microgrid system, thereby improving the safety of the operation of the wind, solar and storage microgrid.

[0086] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0087] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A voltage support method for a wind-solar-storage microgrid system for voltage support, the wind-solar-storage microgrid system comprising: The synchronous phasor measurement device and the flexible AC power transmission equipment are characterized in that the method comprises: A plurality of measurement channels are set in the wind-solar-storage microgrid, and each measurement channel in the operation process of the wind-solar-storage microgrid is monitored in real time by the synchronous phasor measurement device to obtain measurement data of each measurement channel; Select multiple dominant directions of electric energy change in the wind-solar-storage microgrid according to the imbalance between all measured data, determine the distribution characteristics of all measured data in each dominant direction, and decompose all measured data into voltage characteristic curves of multiple alternating voltages based on the distribution characteristics; The characteristic operators of the resonant disturbance in the wind-solar-storage microgrid are identified from each voltage characteristic curve, and multiple mode components related to subsynchronous oscillation are screened out from all voltage characteristic curves according to all the characteristic operators; Each mode component is resolved into a modulation signal in the complex domain, and the instantaneous frequency of the voltage in each measurement channel is tracked through all the modulation signals to obtain the oscillation characteristic parameters; When the oscillation characteristic parameter exceeds a preset threshold, the flexible AC power transmission equipment in the wind, solar, and storage microgrid is controlled to compensate for the impedance characteristics of the wind, solar, and storage microgrid, thereby supporting the voltage of the wind, solar, and storage microgrid.

2. The method according to claim 1, characterized in that According to the imbalance between all the measured data, multiple dominant directions of power change in the wind-solar-storage microgrid are selected, including: Convert all measurement data into measurement matrix; Determine the measurement matrix to determine the imbalance between all measurement data; Setting a plurality of candidate directions in the hypersphere according to the total number of measurement data; According to the imbalance degree, multiple dominant directions of electric energy change in the wind-solar-storage microgrid are selected from all candidate directions.

3. The method according to claim 1, characterized in that Determining the distribution characteristics of all measurement data in each dominant direction specifically includes: For each dominant direction, all measurement data are projected onto the dominant direction to obtain a projection vector; The distribution characteristics of all the measurement data in the dominant direction are determined according to the projection vector, and then the distribution characteristics of all the measurement data in each dominant direction are obtained.

4. The method according to claim 1, characterized in that The characteristic operators for identifying the resonant interference in the wind-solar-storage microgrid from various voltage characteristic curves specifically include: For each measurement data, determining the fluctuation energy value of each voltage characteristic curve corresponding to the measurement data; According to all the fluctuating energy values, the characteristic operator of the resonant interference in the wind-solar-storage microgrid corresponding to each voltage characteristic curve is determined, and then the characteristic operator of the resonant interference in the wind-solar-storage microgrid corresponding to each voltage characteristic curve in each measured data is obtained.

5. The method according to claim 1, characterized in that Screening out multiple mode components related to subsynchronous oscillations from all voltage characteristic curves according to all characteristic operators means taking all voltage characteristic curves corresponding to characteristic operators greater than a preset resonance threshold as mode components related to subsynchronous oscillations, and obtaining multiple mode components related to subsynchronous oscillations.

6. The method according to claim 1, characterized in that The instantaneous frequency of the voltage in each measurement channel is tracked through all modulation signals, and the oscillation characteristic parameters are obtained, including: Determining the instantaneous frequency function and the instantaneous damping ratio function of each modulation signal; For each measurement channel, the tracking frequency and the tracking damping ratio of the subsynchronous oscillation in the measurement channel are determined according to all instantaneous frequency functions and instantaneous damping ratio functions corresponding to the measurement channel, thereby obtaining the tracking frequency and the tracking damping ratio of the subsynchronous oscillation in each measurement channel; Determine the oscillation frequency of subsynchronous oscillation in the wind-solar-storage microgrid based on all tracking frequencies; The oscillation damping ratio of the subsynchronous oscillation in the wind-solar-storage microgrid is determined according to all tracking damping ratios, and the oscillation frequency and the oscillation damping ratio are used as oscillation characteristic parameters.

7. The method according to claim 1, characterized in that The wind, solar and storage microgrid is a wind, solar and storage complementary microgrid.

8. A wind-solar-storage microgrid system, the wind-solar-storage microgrid system comprising a voltage support unit, characterized in that: The voltage support unit comprises: The acquisition module is used to instruct the synchronized phasor measurement device to perform real-time monitoring on each measurement channel during the operation of the wind-solar-storage microgrid after multiple measurement channels are set in the wind-solar-storage microgrid to obtain measurement data of each measurement channel; A processing module, used to select multiple dominant directions of electric energy change in the wind-solar-storage microgrid according to the imbalance between all the measured data, determine the distribution characteristics of all the measured data in each dominant direction, and decompose all the measured data into voltage characteristic curves of multiple alternating voltages based on the distribution characteristics; The processing module is also used to identify characteristic operators of resonant interference in the wind-solar-storage microgrid from each voltage characteristic curve, and screen out multiple mode components related to subsynchronous oscillation from all voltage characteristic curves according to all characteristic operators; The processing module is also used to resolve each mode component into a modulation signal in the complex domain, and track the instantaneous frequency of the voltage in each measurement channel through all the modulation signals, thereby obtaining the oscillation characteristic parameters; The execution module is used to control the flexible AC transmission equipment in the wind-solar-storage microgrid to compensate for the impedance characteristics of the wind-solar-storage microgrid when the oscillation characteristic parameter exceeds a preset threshold, thereby supporting the voltage of the wind-solar-storage microgrid.

9. A computer device, characterized in that: The computer device comprises a memory and a processor, wherein the memory stores codes, and the processor is configured to obtain the codes and execute the voltage support method according to any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the voltage support method according to any one of claims 1 to 7 is implemented.

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