CN114046869B - Broadband oscillation information online monitoring method and system based on daily disturbance response of power system - Google Patents
Broadband oscillation information online monitoring method and system based on daily disturbance response of power system Download PDFInfo
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- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
- G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
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- 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
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- 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
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Abstract
The invention provides a broadband oscillation information online monitoring method and system based on daily disturbance response of a power system, which comprises the following steps: selecting an active power environment excitation response signal of an observation node as an observed quantity; acquiring the main frequency spectrum distribution of the environment excitation response signal; acquiring singular values and singular vectors of a signal power spectrum matrix; acquiring a dominant oscillation frequency and calculating mode information; obtaining vibration mode information and calculating a left and right eigenvector matrix of the power system, and calculating to obtain the participation factor of the vibration mode of each unit; and carrying out system broadband oscillation safety evaluation on the obtained oscillation mode information, judging the oscillation trend of the system according to the identified mode damping ratio information, and issuing alarm, oscillation mode and oscillation mode information. The on-line monitoring method realizes the identification of the broadband oscillation mode information and the modal information, realizes the identification of the strongly-correlated unit of the negative damping oscillation mode, and improves the early warning and pre-control capability of the electric power system on the oscillation.
Description
Technical Field
The invention relates to the technical field of smart power grids, in particular to the field of monitoring and identifying broadband oscillation of a power system, and particularly relates to a method and a system for monitoring broadband oscillation information on line based on daily disturbance response of the power system.
Background
The large-scale regional power grid interconnection is the general development trend of power systems of various countries in the world. Because of the imbalance between the resource distribution and the economic development in the east and west of China, an urgent need exists for building a large interconnected power grid, and the long-distance, large-capacity and high-efficiency transmission of large-scale new energy such as photovoltaic energy, wind power and the like needs to be realized. With the expansion of the scale of a power grid and the increasing demand of electric power, the large-scale centralized grid connection of new energy makes the structure, the operation mode and the dynamic process of the power grid become more and more complex, and low-frequency power oscillation events occur frequently, which seriously affects the safe and stable operation of the power grid. Meanwhile, with the development of new energy and the construction of an extra-high voltage direct current transmission network, the proportion of low-inertia wind power plants, high-power electronic equipment and the like connected to the power grid is higher and higher, and the problem of subsynchronous oscillation (sso) caused by the wind power plants and the extra-high voltage direct current transmission is increasingly highlighted. At present, low-frequency oscillation and subsynchronous oscillation become outstanding problems influencing safe and stable operation of a system, the low-frequency oscillation can limit power transmission capacity between interconnected power grid areas, the subsynchronous oscillation can deteriorate the technical performance and the economical efficiency of a generator set, the generated shafting torsional oscillation has large influence on a rotor structure, and even the shafting of the generator set can be completely broken. Therefore, the real-time monitoring and online early warning of low-frequency oscillation and subsynchronous oscillation events in the power system are carried out, and effective inhibition measures are implemented, so that the safe and stable operation of the power system is very necessary.
The low-frequency oscillation and subsynchronous oscillation mechanisms and response signals of the power system are different. The low-frequency oscillation is generally insufficient damping after disturbance or continuous relative swing between the rotors of the generator excited by a forced oscillation source and between 0.1 and 2.5 Hz. The subsynchronous oscillation is mainly electromechanical coupling oscillation between 5Hz to 50Hz generated between the unit and the power grid reactive compensation equipment and between the unit and the power electronic controller, generally expressed as shafting torsional oscillation of a rotating motor, and supersynchronous oscillation with oscillation above 50Hz may be generated in a wind power plant. The frequency coverage frequency band difference of the low-frequency oscillation and the subsynchronous/supersynchronous oscillation is too large, and the two types of oscillation can be monitored and analyzed on different levels respectively in the prior art. At present, low-frequency oscillation online monitoring based on WAMS/PMU is relatively mature, and an effective monitoring means for sub/super synchronous oscillation brought by power electronization of a power system is lacked.
With the proposal of broadband measurement and the technical development, the method not only can monitor the traditional 50Hz fundamental wave signal, but also realizes the monitoring of subharmonic/supersynchronous oscillation and the like, and provides a technical means for simultaneously monitoring the low-frequency oscillation and the subsynchronous oscillation. When the broadband synchronous monitoring of low-frequency oscillation and sub/super synchronous oscillation is carried out, the applicable mode identification method is of great importance.
The existing low-frequency oscillation online monitoring method has great defects and cannot meet the requirements of actual broadband oscillation online monitoring of a power grid, for example, a Prony method can only analyze free oscillation signals and cannot meet the requirements of real-time monitoring of the power grid, a frequency domain decomposition method is taken as a common method for identifying noise-like signals of daily response, but the method needs to select a frequency range in advance before estimation, and errors generated in power spectrum estimation can influence identification results.
Disclosure of Invention
In view of the defects in the prior art, the present invention aims to provide a method and a system for online monitoring of broadband oscillation information based on a daily disturbance response of a power system, so as to realize an estimation method for automatically selecting a mode frequency, a power spectrum matrix singular value, a singular vector and a vibration mode without cross-power spectrum estimation, so that the calculation speed of the method for online monitoring of broadband oscillation information of the daily disturbance response of the power system is increased, the method and the system are more convenient to apply to online monitoring of broadband oscillation, identification of broadband oscillation mode information and modal information of the power system is realized, identification of strongly-related units in a negative damping oscillation mode is realized, a basis is provided for oscillation suppression, and the early warning pre-control capability of the power system on oscillation is improved.
In order to achieve the above object, a first aspect of the present invention provides an online monitoring method for broadband oscillation information based on daily disturbance response of a power system, including the following steps:
and 6, carrying out system broadband oscillation safety evaluation and judgment on the obtained oscillation mode information, and judging the oscillation trend of the system according to the identified mode damping ratio information:
for a strong damping oscillation mode, sending oscillation mode and oscillation mode information;
and for the weak damping oscillation mode, sending emergency alarm information and oscillation mode information.
In the step 1, the time sequence is constructed by the following method:
and (t) is the value of the electromagnetic power of the observation node at the time t, and a time series analysis sample X (t) is constructed:
X(t)＝[x(t),x(t+1),…,x(t+m-1)]
wherein m is the number of x (t) in the time series analysis sample X (t).
In step 3, obtaining singular values and singular vectors of the signal power spectrum matrix based on the power spectrum energy distribution includes:
if n observation nodes are selected, n signals observed by the nodes form a time sequence, and the singular value of the signal power spectrum matrix is
The corresponding singular vector is σ · H (ω)j)；
Wherein Si(ωj) Is a frequency of omegajAnalyzing the AR spectrum of the sample by using the ith time series, wherein the sigma is the standard deviation of the AR series, and H (omega)j) Is the transfer function of the AR sequence.
In step 4, a singular value curve is drawn according to the singular value to obtain a dominant oscillation frequency, including:
respectively smoothing the singular value curves by using window functions with different sizes and scales, and selecting local extreme points after smoothing operation is performed on the window function corresponding to a certain scale each time; increasing the weight of the extreme point selected for multiple times;
and after the smoothing processing is finished for the preset times, taking the extreme point with the maximum weight as the true extreme point of the curve, namely the dominant oscillation frequency of the signal.
In the step 5, the following method is adopted to obtain the oscillation mode participation factors of each unit:
the singular value vector is subjected to modulus value calculation and normalization to obtain the vibration mode, a matrix formed by singular vectors is a right eigenvector matrix, the pseudo-inverse is a left eigenvector matrix, and the unit oscillation mode participation factor can be obtained according to the following formula:
where n is the number of observation nodes, wijIs the ith row and jth column element, v, of the right eigenvector matrixjiIs the ith row and the jth column element of the left eigenvector matrix.
In step 5, the system broadband oscillation safety evaluation and judgment are performed based on an enhanced frequency domain decomposition method (EFDD) or a frequency domain spatial domain decomposition method (FSDD), and the alarm information is sent, which specifically includes:
(1) when the mode damping ratio xi is greater than 5%, judging that the oscillation mode is safe, and sending oscillation mode information and modal information;
(2) and when the mode damping ratio xi is less than or equal to 5%, judging that the oscillation mode is unsafe, wherein:
if the mode damping ratio is within the range of more than or equal to 3% and less than or equal to xi, orange alarm information is sent;
and if the mode damping ratio xi is less than 3%, sending red alarm information, and issuing corresponding oscillation mode information and modal information.
The second aspect of the present invention provides an online monitoring system for broadband oscillation information based on daily disturbance response of an electrical power system, including:
the module is used for selecting an active power environment excitation response signal of an observation node as an observed quantity based on the broadband measurement platform and constructing a time sequence;
a module for performing power spectrum analysis on the constructed time sequence by adopting an AR spectrum estimation method to obtain power spectrum energy distribution of the signal;
a module for obtaining singular values and singular vectors of a signal power spectrum matrix based on power spectrum energy distribution;
a module for drawing a singular value curve according to the singular value, obtaining a dominant oscillation frequency and determining oscillation mode information;
the module is used for determining vibration mode information according to the singular vectors and calculating a left eigenvector matrix and a right eigenvector matrix of the power system so as to obtain the participation factors of the vibration modes of the units;
and the module is used for carrying out system broadband oscillation safety evaluation and judgment on the obtained oscillation mode information and judging the oscillation trend of the system according to the identified mode damping ratio information, wherein:
for a strong damping oscillation mode, sending oscillation mode and oscillation mode information;
and for the weak damping oscillation mode, sending emergency alarm information and oscillation mode information.
A third aspect of the present invention provides a computer system for online monitoring of broadband oscillation information based on daily disturbance response of a power system, comprising:
one or more processors;
a memory storing instructions that are operable, when executed by the one or more processors, to cause the one or more processors to perform operations comprising performing the processes of the foregoing online monitoring method.
A fourth aspect of the invention proposes a computer-readable medium storing software comprising instructions executable by one or more computers, which when executed by the one or more computers perform the process of the aforementioned online monitoring method.
Therefore, according to the broadband oscillation information online monitoring method and system based on the daily disturbance response of the power system, which are provided by the exemplary scheme of the invention, the power spectrum estimation is carried out on the environment excitation response signal through the AR spectrum, the singular value and the singular vector of the power spectrum matrix are determined, the oscillation frequency and the damping mode information are obtained through calculation by an enhanced frequency domain decomposition method or a frequency domain space domain decomposition method, the oscillation mode information is calculated according to the singular vector, the oscillation safety of the system is evaluated according to the damping ratio, the oscillation mode information and the mode information are sent, and the orange and red alarm information is generated according to different severity degrees under the condition of weak damping.
From the technical scheme of the invention, compared with the prior art, the invention has the following remarkable advantages:
1. the invention overcomes the problem that the traditional low-frequency oscillation and the secondary/super-synchronous oscillation on-line monitoring can not be simultaneously considered, improves the adaptability of the existing frequency domain decomposition method to oscillation identification, realizes the synchronous on-line monitoring of the low-frequency oscillation and the secondary/super-synchronous oscillation, and gives oscillation alarm information according to the difference of the damping result identification;
2. the method adopts the AR spectrum to replace the estimation of the self-power spectrum, avoids the process of time-frequency domain conversion on the discrete sequence, does not have the problems of leakage, variance and the like in the periodogram method, and reduces the estimation error; meanwhile, the process of estimating singular values and singular value vectors of a power spectrum matrix of the self-power spectrum is combined, so that the estimation of cross-power spectrum is not needed, and the calculation speed is increased;
3. the invention provides a method for automatically selecting the leading oscillation frequency, manual selection is not needed, and noise and trend items have small interference on result selection; the method for estimating the modal information acquires more broadband oscillation information, realizes the identification of a strongly-correlated unit in a negative damping oscillation mode according to participation factors, and provides a basis for oscillation suppression;
4. the broadband oscillation information online monitoring method based on the daily disturbance response of the power system realizes online monitoring and early warning of low-frequency oscillation in an interconnected power grid and sub/super synchronous oscillation occurring in high-proportion power electronic access, provides oscillation mode information and modal information, and improves the capability of the power grid for coping with broadband oscillation accidents.
It should be understood that all combinations of the foregoing concepts and additional concepts described in greater detail below can be considered as part of the inventive subject matter of this disclosure unless such concepts are mutually inconsistent. In addition, all combinations of claimed subject matter are considered a part of the presently disclosed subject matter.
The foregoing and other aspects, embodiments and features of the present teachings can be more fully understood from the following description taken in conjunction with the accompanying drawings. Additional aspects of the present invention, such as features and/or advantages of exemplary embodiments, will be apparent from the description which follows, or may be learned by practice of specific embodiments in accordance with the teachings of the present invention.
Drawings
The figures are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. Embodiments of various aspects of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
fig. 1 is a flow chart illustrating a method for on-line monitoring of broadband oscillation information of a broadband measured power system daily disturbance response according to some embodiments of the present invention.
FIG. 2 is a graph illustrating an example of an active power environment stimulus response signal curve according to some embodiments of the present invention, which is a plot of the active power versus time of the daily disturbance response of the power system.
Fig. 3 is a diagram illustrating an example of a broadband oscillating signal AR spectrum according to some embodiments of the invention.
Fig. 4 is a diagram illustrating an example of a singular value curve and a selected dominant frequency according to some embodiments of the invention.
Fig. 5 is a diagram illustrating an example of an oscillation mode according to some embodiments of the present invention.
FIG. 6 is a diagram illustrating one example of a crew participation factor in accordance with some embodiments of the present invention.
Detailed Description
In order to better understand the technical content of the present invention, specific embodiments are described below with reference to the accompanying drawings.
In this disclosure, aspects of the present invention are described with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. Embodiments of the present disclosure are not necessarily intended to include all aspects of the invention. It should be appreciated that the various concepts and embodiments described above, as well as those described in greater detail below, may be implemented in any of numerous ways, as the disclosed concepts and embodiments are not limited to any one implementation. In addition, some aspects of the present disclosure may be used alone, or in any suitable combination with other aspects of the present disclosure.
According to an embodiment of the present invention, a method for monitoring broadband oscillation information on line based on daily disturbance response of an electrical power system is combined with an exemplary implementation flow shown in fig. 1, and the process includes:
and 6, carrying out system broadband oscillation safety evaluation and judgment on the obtained oscillation mode information, and judging the oscillation trend of the system according to the identified mode damping ratio information: for a strong damping oscillation mode, sending oscillation mode and oscillation mode information; and for the weak damping oscillation mode, sending emergency alarm information and oscillation mode information.
The implementation and/or effects of certain examples of the invention are described in more detail below in connection with the flow chart shown in fig. 1 and some preferred or alternative examples of the invention.
[ Online data acquisition and preprocessing ]
Based on a broadband measurement platform, an active power environment excitation response signal of an observation node is selected as an observed quantity, and a time sequence is constructed.
In the foregoing step 1, with reference to fig. 1, based on the broadband measurement platform, a power plant, a wind farm access node, a dc converter station, and a substation with a voltage class of 500kV or more, which are equipped with the broadband measurement device, are preferably selected and set as observation nodes of the active power daily disturbance response signals.
In this step, measurement data is obtained from the wide-band measurement system (if preprocessing is required, the measurement data may be preprocessed, for example, trend removing items, filtering processing, and the like), and the method may be implemented by using a conventional technical means, for example, a method for eliminating a non-stationary trend item of a disturbed track of an electric power system, which is proposed by people such as duckweed, and a method for identifying a low-frequency oscillation mode of an electric power system, which is proposed by people such as Zhang and jin Tao, and is not described herein again.
[ construction of time series ]
With reference to fig. 1, after the active power response data of the observation node is obtained, a time sequence is constructed in the following manner to facilitate subsequent analysis and judgment, and the time sequence constructed according to the active power response data of the node in this embodiment is shown in fig. 2.
As an alternative example, the time series is constructed as follows:
let x (t) be the value of the electromagnetic power of the observation node at the time t, and generate a time series analysis sample X (t):
X(t)＝[x(t),x(t+1),…,x(t+m-1)]
wherein m is the number of x (t) in the time series analysis sample X (t).
[ estimation of AR Spectrum ]
And performing power spectrum analysis on the constructed time sequence by adopting an AR spectrum estimation method to obtain the power spectrum energy distribution of the signal.
With reference to fig. 1, for AR spectral analysis of a constructed time series of samples, data is first constructed in the form of the following formula:
where u (n) is mean zero variance σ2The white noise sequence of (a); p is the AR model order; a iskAre model parameters of the k-th order.
The PSD estimate of the signal x (n) can be derived by the transfer function h (z) of the AR system:
the estimation of the AR spectrum aims to solve the AR model parameters, which parameter estimation can use the Burg method.
By analyzing the power spectrum of the signals of the plurality of observation nodes, a frequency band in which signal energy is mainly concentrated can be obtained, wherein the frequency band in which energy is concentrated can reflect parameter information of an oscillation mode in the system, and fig. 3 is an AR spectrum result.
In this step, the parameter estimation based on the Burg method can be implemented by using the prior art means, for example, the improved algorithm based on the inter-harmonic spectrum estimation of the autoregressive model proposed by magnich et al, and the wind shear wind speed estimation method based on the Burg improved algorithm proposed by royal road break and zhanggan are not described herein again.
[ power spectrum matrix singular value and singular vector calculation ]
And acquiring singular values and singular vectors of the signal power spectrum matrix based on the power spectrum energy distribution.
With reference to fig. 1, if n observation nodes are selected, and n signals observed by the nodes form a time sequence, the singular value of the signal power spectrum matrix is
The corresponding singular vector is σ · H (ω)j)；
Wherein Si(ωj) Is a frequency of omegajAnalyzing the AR spectrum of the sample by using the ith time series, wherein the sigma is the standard deviation of the AR series, and H (omega)j) Is the transfer function of the AR sequence.
[ acquisition of dominant oscillation frequency ]
And leading the oscillation frequency to be selected, and selecting a peak value in a singular value curve.
In the embodiment of the invention, window functions with different sizes and scales are used for respectively smoothing singular value curves, and after smoothing operation is carried out on the window function corresponding to a certain scale each time, local extreme points are selected; wherein, for the extreme points selected for many times, the weight is increased; and after the smoothing processing is finished for a preset number of times, taking the extreme point with the maximum weight as the true extreme point of the curve, namely the dominant oscillation frequency of the signal.
The singular value curve and the selected dominant frequency are smoothed according to the embodiment of the present invention as shown in fig. 4, wherein the number of smoothing is 50.
As an alternative embodiment, we first use a window function with a scale s to smooth the singular value curve, and after the processing, the local extrema are grouped into a set P, and are stored in a set O, where the set O is used to store all the local extrema.
And then increasing the scale s, performing smoothing again, judging that the newly generated set P is the closest point to the old set O as a peak value which needs to be selected really, and forming the points into a set I:
the peak value is weighted by the curve value corresponding to the set I, and the weight increment Δ C is:
△C(I(p))←v(I(p))·s2
and taking the extreme point with the maximum weight as the true extreme point of the curve, namely the dominant oscillation frequency of the corresponding signal after finishing multiple smoothing for a preset number of times.
In the embodiment of the present invention, the preset number of smoothing processes may be generally selected to be 50 smoothing processes.
In an alternative embodiment, where the scale s is selected as a plurality of values with equal preset smoothing times at the same interval between 0 and n/2 on the logarithmic axis, the window function may be selected as a half-sine window or a panning window.
As described above, in the case of the preset 50 smoothing processes, the value of the scale s is selected to be 50 values at the same interval between 0 and n/2 on the logarithmic axis.
[ oscillation mode information calculation ]
With reference to fig. 1, step 5 obtains oscillation mode information by the following method:
the singular value vector is subjected to modulus value calculation and normalization to obtain the vibration mode, a matrix formed by singular vectors is a right eigenvector matrix, the pseudo-inverse is a left eigenvector matrix, and the unit oscillation mode participation factor can be obtained according to the following formula:
where n is the number of observation nodes, wijIs the ith row and jth column element, v, of the right eigenvector matrixjiIs the ith row and the jth column element of the left eigenvector matrix.
Fig. 5 and 6 show examples of obtaining the mode shapes and the participation factors of the units corresponding to different oscillation modes according to the embodiment of the invention.
[ analysis of oscillation mode information ]
With reference to fig. 1, according to the pattern damping information identified in step 4, evaluating the system broadband oscillation security and issuing warning information in step 6, wherein an Enhanced Frequency Domain Decomposition (EFDD) or a frequency domain spatial domain decomposition (FSDD) may be adopted to evaluate and judge the system broadband oscillation security, and wherein the warning and issuing is performed according to the pattern damping ratio ξ:
(1) when the mode damping ratio xi is greater than 5%, judging that the oscillation mode is safe, and sending oscillation mode information and modal information;
(2) and when the mode damping ratio xi is less than or equal to 5%, judging that the oscillation mode is unsafe, wherein:
if the mode damping ratio is within the range of more than or equal to 3% and less than or equal to 5%, orange alarm information is sent;
and if the mode damping ratio xi is less than 3%, sending red alarm information and issuing corresponding oscillation mode information and mode information.
The implementation of one or more embodiments of the invention is based on the online monitoring and analysis of the broadband oscillation of the power system implemented by the broadband measurement platform, and the AR spectrum is adopted to replace the estimation of the self-power spectrum, so that the problems of leakage, variance and the like existing in the process of estimating the power spectrum by a periodogram method are avoided, and the estimation error is reduced; in the process of estimating the singular value and the singular value vector of the power spectrum matrix, only the estimation of an AR spectrum, namely a self-power spectrum, is needed, and the estimation of a cross-power spectrum is not needed, so that the calculation speed is improved; the proposed method for selecting the dominant oscillation frequency can avoid the interference of noise and trend items on the result selection, and realize the automatic selection of the oscillation mode; the given estimation method of the modal information can obtain the estimation of the mode shape and the participation factor; the oscillation safety is evaluated according to the damping identification, different alarm information is sent for the severity of the unsafe oscillation mode, the problem that the traditional low-frequency oscillation and the subsynchronous/supersynchronous oscillation on-line monitoring cannot be considered simultaneously is solved, the adaptability of the existing frequency domain decomposition method to the oscillation identification is improved, and the synchronous on-line monitoring and analyzing functions of the low-frequency oscillation and the subsynchronous/supersynchronous oscillation are realized.
It should be understood that, in some embodiments, the above-mentioned method for monitoring broadband oscillation information on line based on daily disturbance response of an electric power system is implemented in, for example, a monitoring computer array, a server array, or a cloud computing system, a cloud server, where a memory for data storage, at least one processor for computation and processing, a network transceiver module, and a data transmission interface are usually disposed in the monitoring computer, the monitoring computer array, the server, and the server array which are arranged in a certain physical space, and data transmission and communication are performed between them via a bus, so as to implement storage, invocation, and processing of data, thereby implementing the above-mentioned method for monitoring on line.
The invention can also be configured to be implemented in the following manner by combining the broadband oscillation information online monitoring method based on the daily disturbance response of the power system with the embodiments shown in fig. 1 to 6 and described above.
Broadband oscillation information online monitoring system based on daily disturbance response of power system
The broadband oscillation information online monitoring system based on the daily disturbance response of the power system comprises:
the module is used for selecting an active power environment excitation response signal of an observation node as an observed quantity based on the broadband measurement platform and constructing a time sequence;
a module for performing power spectrum analysis on the constructed time sequence by adopting an AR spectrum estimation method to obtain power spectrum energy distribution of the signal;
a module for obtaining singular values and singular vectors of a signal power spectrum matrix based on power spectrum energy distribution;
a module for drawing a singular value curve according to the singular value, obtaining a dominant oscillation frequency and determining oscillation mode information;
the module is used for determining vibration mode information according to the singular vectors and calculating a left eigenvector matrix and a right eigenvector matrix of the power system so as to obtain the participation factors of the vibration modes of the units;
and the module is used for carrying out system broadband oscillation safety evaluation and judgment on the obtained oscillation mode information and judging the oscillation trend of the system according to the identified mode damping ratio information, wherein:
for a strong damping oscillation mode, sending oscillation mode and oscillation mode information;
and for the weak damping oscillation mode, sending emergency alarm information and oscillation mode information.
Therefore, according to the broadband oscillation information online monitoring method and system based on the daily disturbance response of the power system, which are provided by the exemplary scheme of the invention, the power spectrum estimation is carried out on the environment excitation response signal through the AR spectrum, the singular value and the singular vector of the power spectrum matrix are determined, the oscillation frequency and the damping mode information are obtained through calculation by an enhanced frequency domain decomposition method or a frequency domain space domain decomposition method, the oscillation mode information is calculated according to the singular vector, the oscillation safety of the system is evaluated according to the damping ratio, the oscillation mode information and the mode information are sent, and the orange and red alarm information is generated according to different severity degrees under the condition of weak damping.
In another embodiment, the broadband oscillation information online monitoring system based on daily disturbance response of the power system of the foregoing embodiment is configured to be stored in a computer system or a server in a memory in the form of an instruction set that can be called and executed by a processor, so that when being called, the instruction set executes the process of the broadband oscillation online monitoring method based on broadband measurement.
[ computer System ]
The computer system for the on-line monitoring of the broadband oscillation information based on the daily disturbance response of the power system comprises the following components:
one or more processors;
a memory storing instructions that are operable, when executed by the one or more processors, to cause the one or more processors to perform operations comprising performing the processes of the aforementioned online monitoring method.
[ computer-readable Medium ]
A computer-readable medium storing software according to an embodiment of the present invention, the software including instructions executable by one or more computers, the instructions, when executed by the one or more computers, performing the process of the aforementioned online monitoring method.
Although the invention has been described with reference to preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention should be determined by the appended claims.
Claims (9)
1. A broadband oscillation information online monitoring method based on daily disturbance response of a power system is characterized by comprising the following steps:
step 1, selecting an active power environment excitation response signal of an observation node as an observed quantity based on a broadband measurement platform, and constructing a time sequence;
step 2, performing power spectrum analysis on the constructed time sequence by adopting an AR spectrum estimation method to obtain power spectrum energy distribution of the signal;
step 3, acquiring singular values and singular vectors of a signal power spectrum matrix based on power spectrum energy distribution;
step 4, drawing a singular value curve according to the singular value to obtain a dominant oscillation frequency and determine oscillation mode information;
step 5, determining vibration mode information according to the singular vectors obtained in the step 3, and calculating a left and right eigenvector matrix of the power system, so as to obtain oscillation mode participation factors of each unit;
and 6, carrying out system broadband oscillation safety evaluation and judgment on the obtained oscillation mode information, and judging the oscillation trend of the system according to the identified mode damping ratio information:
for a strong damping oscillation mode, sending oscillation mode and oscillation mode information;
and for the weak damping oscillation mode, sending emergency alarm information and oscillation mode information.
2. The method for on-line monitoring the broadband oscillation information based on the daily disturbance response of the power system according to claim 1, wherein in the step 1, the time sequence is constructed by adopting the following method:
and setting x (t) as a value of the electromagnetic power of the observation node at the time t, and constructing a time sequence analysis sample X (t):
X(t)＝[x(t),x(t+1),…,x(t+m-1)]
wherein m is the number of x (t) in the time series analysis sample X (t).
3. The method for on-line monitoring of broadband oscillation information based on daily disturbance response of a power system according to claim 2, wherein the step 3 of obtaining singular values and singular vectors of a signal power spectrum matrix based on power spectrum energy distribution comprises:
if n observation nodes are selected, n signals observed by the nodes form a time sequence, and the singular value of the signal power spectrum matrix is
The corresponding singular vector is σ · H (ω)j)；
Wherein Si(ωj) Is a frequency of omegajAnalyzing the AR spectrum of the sample by using the ith time series, wherein the sigma is the standard deviation of the AR series, and H (omega)j) Is the transfer function of the AR sequence.
4. The method for on-line monitoring of broadband oscillation information based on daily disturbance response of a power system as claimed in claim 3, wherein in the step 4, a singular value curve is drawn according to singular values to obtain a dominant oscillation frequency, and the method comprises the following steps:
respectively smoothing the singular value curves by using window functions with different sizes and scales, and selecting local extreme points after smoothing operation is performed on the window functions corresponding to a certain scale each time; increasing the weight of the extreme point selected for multiple times;
and after the smoothing processing is finished for a preset number of times, taking the extreme point with the maximum weight as the true extreme point of the curve, namely the dominant oscillation frequency of the signal.
5. The on-line monitoring method for the broadband oscillation information based on the daily disturbance response of the power system according to claim 1, wherein in the step 5, the participation factors of the oscillation modes of the units are obtained by adopting the following method:
the singular value vector is subjected to modulus value calculation and normalization to obtain the vibration mode, a matrix formed by singular vectors is a right eigenvector matrix, the pseudo-inverse is a left eigenvector matrix, and the unit oscillation mode participation factor can be obtained according to the following formula:
where n is the number of observation nodes, wijIs the ith row and jth column element, v, of the right eigenvector matrixjiIs the ith row and the jth column element of the left eigenvector matrix.
6. The on-line monitoring method for the broadband oscillation information based on the daily disturbance response of the power system according to claim 1, wherein in the step 5, the system broadband oscillation safety evaluation and judgment are performed based on an enhanced frequency domain decomposition method (EFDD) or a frequency domain spatial domain decomposition method (FSDD), and the alarm information is sent out, specifically comprising:
(1) when the mode damping ratio xi is greater than 5%, judging that the oscillation mode is safe, and sending oscillation mode information and modal information;
(2) and when the mode damping ratio xi is less than or equal to 5%, judging that the oscillation mode is unsafe, wherein:
if the mode damping ratio is within the range of more than or equal to 3% and less than or equal to 5%, orange alarm information is sent;
and if the mode damping ratio xi is less than 3%, sending red alarm information and issuing corresponding oscillation mode information and mode information.
7. A broadband oscillation information online monitoring system based on daily disturbance response of a power system is characterized by comprising:
the module is used for selecting an active power environment excitation response signal of an observation node as an observed quantity based on the broadband measurement platform and constructing a time sequence;
a module for performing power spectrum analysis on the constructed time sequence by adopting an AR spectrum estimation method to obtain power spectrum energy distribution of the signal;
a module for obtaining singular values and singular vectors of a signal power spectrum matrix based on power spectrum energy distribution;
a module for drawing a singular value curve according to the singular value, obtaining a dominant oscillation frequency and determining oscillation mode information;
the module is used for determining vibration mode information according to the singular vectors and calculating a left eigenvector matrix and a right eigenvector matrix of the power system so as to obtain the participation factors of the vibration modes of the units;
and the module is used for carrying out system broadband oscillation safety evaluation and judgment on the obtained oscillation mode information and judging the oscillation trend of the system according to the identified mode damping ratio information, wherein:
for a strong damping oscillation mode, sending oscillation mode and oscillation mode information;
and for the weak damping oscillation mode, sending emergency alarm information and oscillation mode information.
8. A computer system for online monitoring of broadband oscillation information based on daily disturbance response of a power system, comprising:
one or more processors;
a memory storing instructions that are operable, when executed by the one or more processors, to cause the one or more processors to perform operations comprising performing processes of the method of any of claims 1-6.
9. A computer-readable medium storing software, the software comprising instructions executable by one or more computers to perform the process of any one of the methods of claims 1-6 when executed by the one or more computers.
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