CN117254574A - Energy storage power distribution and emergency power supply system - Google Patents
Energy storage power distribution and emergency power supply system Download PDFInfo
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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
- H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
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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
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
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Abstract
The invention relates to the technical field of electric power, in particular to an energy storage power distribution and emergency power supply system. The system comprises: an energy storage power distribution control part and an emergency power supply control part; the energy storage and distribution control part is configured to monitor the power quality of the target in real time, and when the power quality is lower than a set standard, the stored power is released from the energy storage equipment and transmitted to the target; the emergency power supply part is configured to control the transmitted power when the stored power is released from the energy storage equipment by the energy storage power distribution control part. The invention improves the stability and reliability of the power distribution network, effectively reduces the power failure risk and promotes the intelligent upgrading of the power system.
Description
Technical Field
The invention belongs to the technical field of electric power, and particularly relates to an energy storage power distribution and emergency power supply system.
Background
With the continuous development and application of energy, the electric power system plays a vital role in the modern society. However, stability and quality issues of power systems remain a challenging area, especially under ever-increasing power demands. Power quality has been a key factor in power system stability and reliability. In order to ensure proper operation of the power system, power quality assessment and problem diagnosis are vital tasks.
Over the past several decades, a series of power quality assessment and problem diagnosis techniques have emerged that have helped to some extent in the maintenance and improvement of power systems. However, as power demand increases and power systems become complex, conventional power quality assessment methods increasingly expose some limitations. The following are problems in the prior art: complexity of power quality monitoring: traditional power quality monitoring methods rely mainly on sensors and monitoring equipment, requiring significant human and material investment for maintenance and management. This not only increases the cost, but also limits its feasibility in large-scale applications. Challenges of time-frequency analysis: the characteristics of the power signal are embodied in both the time domain and the frequency domain, so that time-frequency analysis is required to fully understand the characteristics of the power signal. However, the traditional time-frequency analysis method has limited effect on extracting local characteristics of signals, and is difficult to accurately capture the problems of transients, harmonics and the like. Data processing and interpretation difficulties: the traditional power quality monitoring method generates huge data volume, and is relatively complex to process and interpret. How to extract useful information from mass data and to perform problem diagnosis and decision is a problem to be solved urgently.
Disclosure of Invention
The invention mainly aims to provide an energy storage power distribution and emergency power supply system, which improves the stability and reliability of a power distribution network, effectively reduces the risk of power failure and promotes the intelligent upgrading of a power system.
In order to solve the problems, the technical scheme of the invention is realized as follows:
an energy storage power distribution and emergency power supply system, the system comprising: an energy storage power distribution control part and an emergency power supply control part; the energy storage and distribution control part is configured to monitor the power quality of the target in real time, and when the power quality is lower than a set standard, the stored power is released from the energy storage equipment and transmitted to the target; the emergency power supply part is configured to control the transmitted power when the stored power is released from the energy storage equipment by the energy storage power distribution control part, and specifically comprises the following steps: the method includes the steps of firstly using a frequency control valve to transmit power, adjusting the frequency of the transmitted power so that the frequency of the transmitted power is reduced to be within a set first threshold range, and then shunting the transmitted power so that the standard deviation of energy of the power along with frequency change is within a set second threshold range.
Further, the method for monitoring the power quality of the target in real time by the energy storage and distribution control part comprises the following steps: acquiring voltage and current signals in a target, and performing filtering and noise reduction processing to obtain discrete voltage signals and discrete current signals; performing coefficient decomposition on the discrete current signals and the discrete voltage signals by using a preset coefficient decomposition model to obtain a voltage decomposition coefficient and a current decomposition coefficient; calculating the energy distribution ratio and harmonic content of the current signal under each scale based on the current decomposition coefficient; calculating the phase offset of the voltage signal under each scale based on the voltage decomposition coefficient; calculating an electric power quality value based on an average value of energy distribution ratios of the current signals at each scale, a standard deviation of harmonic content of the current signals at each scale, and an average value of phase shifts of the voltage signals at each scale; when the power quality value is lower than the set quality judgment value, judging that the power quality is lower than the set standard.
Further, the method for obtaining the voltage decomposition coefficient and the current decomposition coefficient by respectively performing coefficient decomposition on the discrete current signal and the discrete voltage signal by using a preset coefficient decomposition model comprises the following steps: the discrete current signal and the discrete voltage signal are coefficient decomposed, respectively, using the following formula:
；
wherein,is a voltage discrete signal;is a current discrete signal;is the voltage decomposition coefficient;is the current decomposition coefficient;indexing for sampling points;is in wavelet scale;for the wavelet complex conjugate function, the following formula is used for the expression:
；
wherein,is an imaginary unit of number and is,is the center frequency of the wave-shaped wave,is the argument of the complex conjugate function of the wavelet,；is a natural base number.
Further, the method for calculating the energy distribution ratio and the harmonic content of the current signal under each scale based on the current decomposition coefficient comprises the following steps: the energy distribution ratio of the current signal at each scale is calculated using the following formula:
；
wherein,is of the scale ofThe following energy distribution ratio;
the harmonic content of the current signal at each scale is calculated using the following formula:
；
wherein,is of the scale ofHarmonic content below;is the fundamental frequency of the current signal;the harmonic wave multiple is a set value, and the value range is 2 to 10.
Further, the method for calculating the phase offset of the voltage signal under each scale based on the voltage decomposition coefficient comprises the following steps: the phase offset of the voltage signal at each scale is calculated using the following formula:
；
wherein,is an arctangent function that can handle four quadrants,in order to take the imaginary part of the complex number for calculation,calculating for taking the real part of the complex number;is thatComplex conjugate of (a);is of the scale ofThe phase of the lower voltage signal is shifted.
Further, the power quality value is calculated using the following formula:
power quality value = average value of energy distribution ratio of current signal at each scale 0.4+ standard deviation of harmonic content of current signal at each scale 0.3+ average value of phase shift of voltage signal at each scale 0.3.
Further, the emergency power supply part divides the transmitted power so that the standard deviation of the energy of the power with the change of frequency is within a set second threshold value range, and the method comprises the following steps: collecting the current of the transmitted power to obtain a current time sequence, normalizing the current time sequence to make the average value of the current time sequence be zero, and eliminating the direct current component; splitting the normalized current time sequence into overlapped subsequences, and constructing a Hankel matrix; singular value decomposition is carried out on the constructed Hankel matrix to obtain a diagonal matrix; constructing a joint matrix based on the diagonal matrix, and carrying out Fourier transform on the joint matrix to obtain a Hilbert spectrum; calculating a time-frequency representation by using the Hilbert spectrum; nonlinear diffusion is carried out on the time-frequency representation; carrying out Fourier transform on the time-frequency representation subjected to nonlinear diffusion to obtain a singular frequency spectrum; calculating the standard deviation of the energy of the singular spectrum along with the frequency change based on the singular spectrum; calculating the current division number based on the set second threshold rangeWhereinThe method comprises the steps of carrying out a first treatment on the surface of the Splitting the current intoA sub-current; wherein,is a singular spectrum of the light,is the angular frequency.
Further, the method for performing nonlinear diffusion on the time-frequency representation comprises the following steps:
nonlinear diffusion of the time-frequency representation is performed using the following formula:
；
wherein,is a time-frequency representation through nonlinear diffusion;is a time-frequency representation;a center frequency that is a nonlinear diffusion;is frequency;time is;a nonlinear parameter with a value ranging from 0.3 to 0.7;for nonlinear adjustment parameters, the value range is 0.25 to 0.56;
further, the current time series is normalized using the following formula:
；
wherein,is a current time series;is the normalized current time series.
Further, the standard deviation of the energy of the singular spectrum along with the frequency change is calculated by using the following formula:
。
wherein,is a component of angular frequency over the frequency spectrum,is the number of frequency samples to be counted,is the frequencyAverage energy at;is the standard deviation of the energy of the singular spectrum with frequency.
The energy storage power distribution and emergency power supply system has the following beneficial effects: the energy storage and distribution control part of the invention introduces a technology of monitoring the power quality in real time, and can accurately capture the characteristics of current and voltage signals. Through deep analysis of the power quality, the system can detect the problems of harmonic waves, transients and the like in real time, so that potential power distribution problems can be early warned and processed in time. This helps to improve the stability and reliability of the distribution network and reduce instabilities due to power quality issues. The emergency power supply part adopts a power splitting strategy to split the transmitted power so as to ensure the stable supply of the power. In emergency situations, such as power interruption or failure, the system can quickly respond and implement power splitting to ensure that critical devices are continuously powered. The intelligent emergency power supply strategy greatly improves the reliability of the power system, and provides reliable emergency guarantee for key time.
Drawings
Fig. 1 is a schematic diagram of a system structure of an energy storage power distribution and emergency power supply system according to an embodiment of the present invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
The following will describe in detail.
The terms "first," "second," "third," "fourth" and the like in the description and in the claims and in the above drawings, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments described herein may be implemented in other sequences than those illustrated or otherwise described herein.
Example 1: referring to fig. 1, an energy storage power distribution and emergency power supply system, the system comprising: an energy storage power distribution control part and an emergency power supply control part; the energy storage and distribution control part is configured to monitor the power quality of the target in real time, and when the power quality is lower than a set standard, the stored power is released from the energy storage equipment and transmitted to the target; the emergency power supply part is configured to control the transmitted power when the stored power is released from the energy storage equipment by the energy storage power distribution control part, and specifically comprises the following steps: the method includes the steps of firstly using a frequency control valve to transmit power, adjusting the frequency of the transmitted power so that the frequency of the transmitted power is reduced to be within a set first threshold range, and then shunting the transmitted power so that the standard deviation of energy of the power along with frequency change is within a set second threshold range.
In particular, the design objective of such energy storage power distribution and emergency power supply systems is to enable real-time monitoring and maintenance of the power quality, while being able to release stored electrical energy from the energy storage device to supply power and to ensure reliable power supply in emergency situations when the power quality is below certain criteria. The system is mainly divided into two parts, namely an energy storage and distribution control part and an emergency power supply control part. The key function of the energy storage and distribution control part is to monitor the power quality of the target. This includes factors such as voltage stability, frequency deviation, harmonic distortion, etc. When the power quality is below a set level, the control portion activates, releases stored electrical energy from the energy storage device, and then transfers the portion of the electrical energy to the desired target. Such real-time power regulation and transmission may ensure that power quality is maintained while avoiding power interruption or power fluctuations from affecting the device. The emergency power supply control part is used for accurately controlling the transmitted electric energy when the energy storage and distribution control part is monitored to release the stored electric energy, so that the stability and the reliability of emergency power supply are ensured. The specific steps of the part are as follows: using a frequency control valve: by using a frequency control valve, the system can adjust the frequency of the transmitted electrical energy to be reduced to within a preset first threshold range. This step ensures that the frequency of the transmitted electrical energy is consistent with the normal power supply, preventing equipment failure or power loss due to frequency instability. Electric energy split: after adjusting the frequency, the system will shunt the transmitted power. This means that the electrical energy is divided into several parts in order to better cope with frequency variations. This operation helps to control the energy distribution of the electric power so that its standard deviation upon frequency change remains within a preset second threshold range. The design of the emergency power supply control portion ensures the stability of the power supply in case of emergency, not just simply releasing the power. Such fine control can prevent problems caused by frequency mismatch or power energy maldistribution. The frequency control valve and the electric energy shunt are used, so that the system can better adapt to the requirement of target equipment on the stability of electric power frequency when the energy storage electric energy is released, and the influence of electric power fluctuation on the equipment is reduced. Traditional power systems often cannot monitor power quality in real time and adjust as needed. The system can respond to the power quality problem rapidly through real-time monitoring and energy storage release, and frequent power interruption in the traditional system is avoided.
Example 2: on the basis of the above embodiment, the method for the energy storage and distribution control part to monitor the power quality of the target in real time includes: acquiring voltage and current signals in a target, and performing filtering and noise reduction processing to obtain discrete voltage signals and discrete current signals; performing coefficient decomposition on the discrete current signals and the discrete voltage signals by using a preset coefficient decomposition model to obtain a voltage decomposition coefficient and a current decomposition coefficient; calculating the energy distribution ratio and harmonic content of the current signal under each scale based on the current decomposition coefficient; calculating the phase offset of the voltage signal under each scale based on the voltage decomposition coefficient; calculating an electric power quality value based on an average value of energy distribution ratios of the current signals at each scale, a standard deviation of harmonic content of the current signals at each scale, and an average value of phase shifts of the voltage signals at each scale; when the power quality value is lower than the set quality judgment value, judging that the power quality is lower than the set standard.
Specifically, the coefficient decomposition model is a technique commonly used in the field of signal processing, and wavelet transformation is one of the most widely used. The core idea of wavelet transformation is to decompose a signal into components of different scales and frequencies to reveal local features and variations of the signal. This is in contrast to conventional fourier transforms, which are mainly used to analyze the frequency characteristics of signals. Wavelet transforms use a set of basis functions called wavelet functions (or parent wavelets) that have local properties in the time and frequency domains. By wavelet transforming the signal we can obtain a set of wavelet coefficients that represent the contributions of the signal at different scales and frequencies.
The purpose of the energy distribution ratio calculation is to analyze the energy distribution of the signal at different scales to determine the frequency domain characteristics of the signal. In the context of power quality, the energy distribution ratio may help us to know the energy distribution of the current signal over different frequency ranges, thereby determining whether frequency anomalies or harmonic components are present. The purpose of harmonic content calculation is to analyze the intensity of harmonic components in the signal and judge whether harmonic problems exist in the power quality. Nonlinear loads and devices in power systems introduce harmonics, resulting in harmonic components of different frequencies in the current and voltage. In power quality assessment, the purpose of the phase offset calculation is to determine the phase stability of the voltage signal. The problems of frequency variation, phase difference, etc. in the power system cause the relative phase of the signals to vary. This can have an impact on the power equipment and loads and even cause equipment failure. The relative phase change condition of the voltage signals under different scales can be known through phase shift calculation. The method is helpful for evaluating the phase stability of the power system, detecting whether the problems of phase imbalance or phase drift exist or not, and accordingly taking appropriate measures to maintain the power quality and the normal operation of equipment.
Example 3: on the basis of the above embodiment, the method for performing coefficient decomposition on the discrete current signal and the discrete voltage signal by using a preset coefficient decomposition model to obtain a voltage decomposition coefficient and a current decomposition coefficient includes: the discrete current signal and the discrete voltage signal are coefficient decomposed, respectively, using the following formula:
；
wherein,is a voltage discrete signal;is a current discrete signal;is the voltage decomposition coefficient;is the current decomposition coefficient;indexing for sampling points;is in wavelet scale;for the wavelet complex conjugate function, the following formula is used for the expression:
；
wherein,is an imaginary unit of number and is,is the center frequency of the wave-shaped wave,is the argument of the complex conjugate function of the wavelet,；is a natural base number.
Specifically, first a voltage signalAnd a current signalIs sampled data over a discrete time domain. Then, the two signals are decomposed by using a preset coefficient decomposition model. Voltage decomposition coefficient obtained after decompositionAnd current decomposition coefficientWe can be helped to understand the energy distribution of the signal at different scales. Is tied inIn the number decomposition, complex conjugate wavelet functions are usedAnd performing signal transformation. The function of this function is to convert the signal from the time domain to the wavelet domain. The complex conjugate wavelet function may be represented by a formula in whichIs the center frequency of the wave-shaped wave,is the argument of the complex conjugate function of the wavelet. Index for each sample pointAnd wavelet scaleAnd respectively carrying out coefficient decomposition on the voltage signal and the current signal according to a given formula. During the decomposition process, allSumming to calculate voltage decomposition coefficientAnd current decomposition coefficient. These coefficients reflect the distribution of the signal at different scales. The voltage and current decomposition coefficients provide the energy distribution of the signal at different scales, thereby helping to understand the frequency domain characteristics of the signal. The change in these coefficients can be used to determine whether there is a concentration or dispersion of energy, a change in frequency content, etc. in the signal. By analyzing these coefficients, a more thorough understanding of the frequency domain characteristics of the voltage and current signals can be achieved, facilitating power quality assessment.
Example 4: on the basis of the above embodiment, the method for calculating the energy distribution ratio and the harmonic content of the current signal at each scale based on the current decomposition coefficient includes: the energy distribution ratio of the current signal at each scale is calculated using the following formula:
；
wherein,is of the scale ofThe following energy distribution ratio;
the harmonic content of the current signal at each scale is calculated using the following formula:
；
wherein,is of the scale ofHarmonic content below;is the fundamental frequency of the current signal;the harmonic wave multiple is a set value, and the value range is 2 to 10.
In particular, the calculation method of the energy distribution ratio aims at quantifying the energy distribution situation of the current signal at different scales, in particular in comparison with the energy distribution of the voltage signal. This helps to determine if the energy of the current signal is relatively high at a certain scale, and the relative energy distribution of the current signal and the voltage signal. For a specific scaleFirst, the current decomposition coefficient is calculatedSum of absolute squares of (i.e.). This sum reflects the energy distribution of the current signal at that scale. At the same time, calculate the current decomposition coefficientSum of absolute squares of (d) and voltage decomposition coefficientSum of absolute squares of (i.e.). This sum represents the energy distribution of the total signal (including the current and voltage signals) at that scale. Calculating an energy distribution ratio using the ratio of the two sums. By the formulaThe energy distribution ratio is calculated. The basic principle of the energy distribution ratio calculation is to compare the energy distribution of the current signal with the energy distribution of the total signal (current and voltage signals). This is achieved by taking the sum of squares of the absolute values of the current decomposition coefficients and the ratio of the sum of squares of the absolute values of the current and voltage decomposition coefficients. The larger the calculation result of the energy distribution ratio is, the higher the energy of the current signal under the scale is, and the larger the energy distribution of the total signal is. In power quality assessment, the calculation of the energy distribution ratio can be used to detect the energy concentration or dispersion of the current signal at different scales. A higher energy distribution ratio implies that there is an anomaly or peak in the current signal at a certain scale, which is an indication of a power quality problem.
The calculation method of the harmonic content aims at evaluating the intensity of harmonic components in the current signal under different scales, in particular the relation with the harmonic components of the fundamental frequency. This helps to determine if there are anomalies in the harmonic content of the current signal, and harmonics at different scalesDistribution of wave components. First, it is necessary to determine the fundamental frequency of the current signalThis is typically an integer multiple of the power frequency. The fundamental frequency is the most dominant frequency component in the current signal and generally corresponds to the standard frequency of the power system (e.g., 50Hz or 60 Hz). For each scaleCalculating harmonic wave multipleThe product of the fundamental frequency, i.e. This will give the harmonic frequencies that should occur at that scale. Coefficient of decomposition to currentSumming the absolute squares of (i.e.). At the same time, calculating the complex conjugate function of the waveletThe function is used to calculate the amplitude of the harmonic frequencies that should occur at that scale. Using the two calculation results, the calculation results are calculated by the formulaCalculating harmonic content. The fundamental principle of harmonic content calculation is to evaluate the intensity of harmonic components in a current signal by comparing the relation between actual harmonic components and expected harmonic components in the current signal. In the calculation, the expected harmonic frequencies are first calculated from the fundamental frequency, and then the magnitudes of these harmonic frequencies in the current signal are calculated. Finally, the amplitude of the expected harmonic frequency and the amplitude of the actual harmonic frequency are combinedAnd comparing to obtain harmonic content. The larger the calculation of the harmonic content, the stronger the harmonic content in the current signal at that scale. By analyzing the harmonic content under different scales, the change condition of the harmonic component in the current signal on the frequency domain can be identified, and the harmonic problem in the power quality can be found. In summary, the harmonic content calculation method provides a measure of the intensity of the harmonic components of the current signal at different scales, and the harmonic characteristics in the current signal can be better understood by comparing the relationship between the actual harmonic components and the expected harmonic components.
Example 5: based on the above embodiment, the method for calculating the phase offset of the voltage signal at each scale based on the voltage decomposition coefficient includes: the phase offset of the voltage signal at each scale is calculated using the following formula:
；
wherein,is an arctangent function that can handle four quadrants,in order to take the imaginary part of the complex number for calculation,calculating for taking the real part of the complex number;is thatComplex conjugate of (a);is of the scale ofThe phase of the lower voltage signal is shifted.
Specifically, phase offset calculationThe basic principle of (a) is to use complex operations to calculate the phase offset between the voltage signal and the current signal. First, calculate the voltage decomposition coefficientCoefficient of current decompositionIs a linear combination of complex numbers and complex conjugates. Then, using the imaginary and real parts of this linear combination as parameters, usingThe function calculates the relative phase angle. This angle represents the relative phase offset between the voltage signal and the current signal. By means of phase offset calculation, the relative phase relation between the voltage signal and the current signal can be known at different scales. This is very useful for assessing phase stability in a power system and phase misalignment between signals.
The principle of the phase offset calculation formula is based on complex operations and arctangent functions, aiming at quantifying the relative phase difference between the voltage signal and the current signal. This calculation formula may help evaluate the phase offset between the voltage and current signals in order to identify phase problems in the power quality evaluation. First, from each scaleLower voltage decomposition coefficientAnd current decomposition coefficientStarting. We need to calculate a linear combination of these two complex numbers by: coefficient of decomposition to currentComplex conjugation is taken to obtainRepresenting complex conjugationIs a current decomposition coefficient of (a). The imaginary and real parts of the linear combination can be used as arctangent functionsIs included in the set of parameters.Is an arctangent function that can process the phase information of four quadrants. By providing the imaginary and real parts as parameters,the function calculates an angle representing the relative phase difference between the voltage signal and the current signal. Final calculation resultIs an angle, and represents that the voltage signal is in scaleThe relative phase offset between the lower and current signals. This angle can be used to measure the phase relationship between the signals.
Example 6: on the basis of the above embodiment, the electric power quality value is calculated using the following formula:
power quality value = average value of energy distribution ratio of current signal at each scale 0.4+ standard deviation of harmonic content of current signal at each scale 0.3+ average value of phase shift of voltage signal at each scale 0.3.
Example 7: on the basis of the above embodiment, the emergency power supply section, the method of splitting the transmitted power so that the standard deviation of the energy of the power with the change of frequency is within the set second threshold value range, includes: collecting the current of the transmitted power to obtain a current time sequence, normalizing the current time sequence to make the average value of the current time sequence be zero, and eliminating the direct current component; splitting the normalized current time sequence into overlapped subsequences, and constructing a Hankel matrix; singular value decomposition is carried out on the constructed Hankel matrix to obtain a diagonal matrix; a joint matrix is constructed based on the diagonal matrix,performing Fourier transform on the joint matrix to obtain a Hilbert spectrum; calculating a time-frequency representation by using the Hilbert spectrum; nonlinear diffusion is carried out on the time-frequency representation; carrying out Fourier transform on the time-frequency representation subjected to nonlinear diffusion to obtain a singular frequency spectrum; calculating the standard deviation of the energy of the singular spectrum along with the frequency change based on the singular spectrum; calculating the current division number based on the set second threshold rangeWhereinThe method comprises the steps of carrying out a first treatment on the surface of the Splitting the current intoA sub-current; wherein,is a singular spectrum of the light,is the angular frequency.
Specifically, the Hankel matrix is a matrix of successive vectors, each of which is a successive segment of the original signal time sequence. The process of constructing the Hankel matrix involves splitting the time sequence into different sub-sequences, which are then arranged in columns to form the matrix. The nature of the Hankel matrix makes it very efficient in capturing the timing characteristics of the signal. The main purpose of constructing the Hankel matrix is to extract useful information from the signal, which is particularly useful in power quality assessment. The construction mode of the Hankel matrix keeps the time sequence information of the signals. By splitting the continuous time sequence into different sub-sequences and forming a matrix, the Hankel matrix can effectively capture the evolution of the signal over time. The signal may contain a large number of data points and constructing the Hankel matrix may map the signal from a high-dimensional space to a lower-dimensional matrix space. This helps to reduce the amount of computation and processing complexity. From the constructed Hankel matrix, the main features of the signals can be extracted by Singular Value Decomposition (SVD) and other methods. These features may be used to analyze the spectral distribution, periodicity, trend, etc. of the signal. The computation of the Hilbert spectrum involves Hilbert transforming the signal to obtain a complex signal. Then, by calculating the amplitude of this complex signal, the energy distribution of the signal at different frequencies can be obtained. The hilbert spectrum may be used to analyze spectral characteristics of the signal, including frequency content, dominant frequencies, and the like. In power quality assessment, the hilbert spectrum can be used to analyze the spectrum of the current signal, and thus learn about harmonics and periodic components in the current signal. SVD can be applied to singular value decomposition to construct a Hankel matrix. SVD is carried out on the constructed Hankel matrix, so that singular values and corresponding singular vectors of the matrix can be obtained. These singular vectors represent the dominant eigenmodes of the signal. In power quality assessment, the purpose of SVD is to extract the main spectrum and periodicity information from the current signal.
Example 8: based on the above embodiment, the method for performing nonlinear diffusion on the time-frequency representation includes:
nonlinear diffusion of the time-frequency representation is performed using the following formula:
；
wherein,is a time-frequency representation through nonlinear diffusion;is a time-frequency representation;a center frequency that is a nonlinear diffusion;is frequency;time is;a nonlinear parameter with a value ranging from 0.3 to 0.7;for nonlinear adjustment parameters, the value range is 0.25 to 0.56.
Specifically, the purpose of nonlinear diffusion is to enhance the local characteristics of the signal by introducing nonlinear operation, so that the important structure of the signal is clearer, and simultaneously noise and smoothing signals are suppressed. Time-frequency representationObtaining a time-frequency representation after nonlinear diffusion through nonlinear diffusion treatment. Nonlinear diffusion uses a specific form of exponential function to adjust the amplitude in the time-frequency representation. The key to nonlinear diffusion is to introduce a nonlinear function that adjusts each frequency component in the time-frequency representation. In the formula, the nonlinear diffusion function is. This function is an exponential form, which is related to frequencyBy correlation ofAndparameters adjust the shape of the function. In non-linear diffusion functionsRepresenting frequency relative to center frequencyIs set in the above-described range (a). This offset is used to determine the range of non-linear diffusion. When the frequency is greatly deviated from the center frequency, the value of the diffusion function is reduced, thereby corresponding to the frequency componentThe amplitude variation is small.
Andparameters that are nonlinear diffusion functions affect the width and shape of the function, respectively. Larger sizeThe values result in a narrower and larger function widthThe values result in a steeper function shape. Adjustment of these parameters affects the extent and effect of nonlinear diffusion. The effect of the nonlinear diffusion function is to enhance certain frequency components in the time-frequency representation. The larger amplitude component is more enhanced, thereby making the important features in the signal more pronounced. Nonlinear diffusion can also suppress low-amplitude noise because the function has a smaller value in the low-amplitude region, thereby reducing the effect of noise on the signal. Nonlinear diffusion is frequency selective, with a strong enhancement effect on components near the center frequency and a small enhancement effect on components far from the center frequency. The principle of nonlinear diffusion is to introduce a nonlinear function to adjust the time-frequency representation to achieve local enhancement and noise suppression of the signal to highlight important features in the signal. This helps to better analyze the time-frequency characteristics of the signal and provides more accurate information in the field of power quality assessment, etc.
Example 9: on the basis of the above embodiment, the current time series is normalized using the following formula:
；
wherein,is a current time series;is the normalized current time series.
Specifically, the method eliminates the direct current component by carrying out normalization processing on the current time sequence to make the average value of the current time sequence be zero, so that the fluctuation characteristic of the signal is better highlighted. This facilitates a more accurate analysis of the periodic components and harmonics of the current signal, etc. characteristics for power quality assessment and problem diagnosis.
Example 10: on the basis of the above embodiment, the standard deviation of the energy of the singular spectrum with the frequency is calculated using the following formula:
。
wherein,is a component of angular frequency over the frequency spectrum,is the number of frequency samples to be counted,is the frequencyAverage energy at;is the standard deviation of the energy of the singular spectrum with frequency.
Specifically, for each frequency component, the square of the difference between it and the average energy is calculated, then the square differences of all frequency components are summed, divided by the number of frequency sampling points, and finally the square root is taken to obtain the standard deviation. This standard deviation represents the fluctuation of the energy distribution of the singular spectrum at different frequencies. Singular spectrum is a technique used in time-frequency domain analysis to extract local features of a signal. It converts a signal from a time domain to a time-frequency domain by using a specific transformation, and then visualizes the signalCharacteristics at different frequencies and times. The main purpose of this formula is to calculate the energy variation of the singular spectrum in frequency. The standard deviation is a statistical indicator that measures the degree of dispersion of the data distribution, and is used here to describe the energy fluctuations of the singular spectrum at different frequencies. In the formulaRepresenting singular spectrum at frequencyThe energy distribution at the location(s),is the corresponding angular frequency component.Expressed in frequencyThe average energy of the singular spectrum at can be regarded as frequencyA desired value of the energy distribution at the location. In the formulaRepresenting singular spectrum at frequencyThe square of the difference between the energy at that point and the average energy. Summation terms in the overall formulaThe sum is made for all the frequency components,is the number of frequency samples. In the formulaThe root mean square of the sum of squares of the differences, i.e. the standard deviation, represents the fluctuation of the energy distribution of the singular spectrum over different frequencies. This isThe principle of the formula is that for the energy distribution of the singular spectrum at different frequencies, the root mean square of the sum of squares of the differences between the singular spectrum and the average energy is calculated, so that an index describing the fluctuation situation of the energy distribution is obtained. The larger the standard deviation is, the more unstable the energy distribution is, and the stronger the fluctuation is; the smaller the standard deviation, the more stable the energy distribution, and the smaller the fluctuation. By calculating the standard deviation of the energy of the singular frequency spectrum along with the frequency change, the quantitative information of the energy fluctuation condition of the current signal on different frequencies can be obtained, the frequency domain characteristics of the signal can be more comprehensively known, and the method is used for power quality evaluation and problem diagnosis.
The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. An energy storage power distribution and emergency power supply system, the system comprising: an energy storage power distribution control part and an emergency power supply control part; the energy storage and distribution control part is configured to monitor the power quality of the target in real time, and when the power quality is lower than a set standard, the stored power is released from the energy storage equipment and transmitted to the target; the emergency power supply part is configured to control the transmitted power when the stored power is released from the energy storage equipment by the energy storage power distribution control part, and specifically comprises the following steps: the method includes the steps of firstly using a frequency control valve to transmit power, adjusting the frequency of the transmitted power so that the frequency of the transmitted power is reduced to be within a set first threshold range, and then shunting the transmitted power so that the standard deviation of energy of the power along with frequency change is within a set second threshold range.
2. The energy storage power distribution and emergency power supply system according to claim 1, wherein the method for the energy storage power distribution control section to monitor the power quality of the target in real time comprises: acquiring voltage and current signals in a target, and performing filtering and noise reduction processing to obtain discrete voltage signals and discrete current signals; performing coefficient decomposition on the discrete current signals and the discrete voltage signals by using a preset coefficient decomposition model to obtain a voltage decomposition coefficient and a current decomposition coefficient; calculating the energy distribution ratio and harmonic content of the current signal under each scale based on the current decomposition coefficient; calculating the phase offset of the voltage signal under each scale based on the voltage decomposition coefficient; calculating an electric power quality value based on an average value of energy distribution ratios of the current signals at each scale, a standard deviation of harmonic content of the current signals at each scale, and an average value of phase shifts of the voltage signals at each scale; when the power quality value is lower than the set quality judgment value, judging that the power quality is lower than the set standard.
3. The energy storage power distribution and emergency power supply system according to claim 2, wherein the method for performing coefficient decomposition on the discrete current signal and the discrete voltage signal by using a preset coefficient decomposition model to obtain a voltage decomposition coefficient and a current decomposition coefficient comprises: the discrete current signal and the discrete voltage signal are coefficient decomposed, respectively, using the following formula:the method comprises the steps of carrying out a first treatment on the surface of the Wherein (1)>Is a voltage discrete signal; />Is a current discrete signal; />Is the voltage decomposition coefficient; />Is the current decomposition coefficient; />Indexing for sampling points; />Is in wavelet scale;for the wavelet complex conjugate function, the following formula is used for the expression: />The method comprises the steps of carrying out a first treatment on the surface of the Wherein (1)>Is imaginary unit, ++>Is the center frequency +.>Is an argument of a wavelet complex conjugate function, +.>；/>Is a natural base number.
4. The energy storage power distribution and emergency power supply system according to claim 3, wherein the method of calculating the energy distribution ratio and harmonic content of the current signal at each scale based on the current decomposition coefficient comprises: the energy distribution ratio of the current signal at each scale is calculated using the following formula:the method comprises the steps of carrying out a first treatment on the surface of the Wherein (1)>For the scale +.>The following energy distribution ratio; the harmonic content of the current signal at each scale is calculated using the following formula:the method comprises the steps of carrying out a first treatment on the surface of the Wherein (1)>For the scale +.>Harmonic content below;is the fundamental frequency of the current signal; />The harmonic wave multiple is a set value, and the value range is 2 to 10.
5. The energy storage power distribution and emergency power supply system of claim 4, wherein the method of calculating the phase offset of the voltage signal at each scale based on the voltage decomposition coefficients comprises: the phase offset of the voltage signal at each scale is calculated using the following formula:the method comprises the steps of carrying out a first treatment on the surface of the Wherein (1)>Is an arctangent function that can handle four quadrants,/>To take the imaginary part of the complex number to calculate +.>To take a plurality ofIs calculated by the real part of (2); />Is->Complex conjugate of (a); />For the scale +.>The phase of the lower voltage signal is shifted.
6. The energy storage power distribution and emergency power supply system of claim 5, wherein the power quality value is calculated using the formula: power quality value = average value of energy distribution ratio of current signal at each scale 0.4+ standard deviation of harmonic content of current signal at each scale 0.3+ average value of phase shift of voltage signal at each scale 0.3.
7. The energy storage power distribution and emergency power supply system according to claim 6, wherein the emergency power supply section divides the transmitted power such that a standard deviation of energy of the power with respect to a frequency is within a set second threshold range, the method comprising: collecting the current of the transmitted power to obtain a current time sequence, normalizing the current time sequence to make the average value of the current time sequence be zero, and eliminating the direct current component; splitting the normalized current time sequence into overlapped subsequences, and constructing a Hankel matrix; singular value decomposition is carried out on the constructed Hankel matrix to obtain a diagonal matrix; constructing a joint matrix based on the diagonal matrix, and carrying out Fourier transform on the joint matrix to obtain a Hilbert spectrum; calculating a time-frequency representation by using the Hilbert spectrum; nonlinear diffusion is carried out on the time-frequency representation; carrying out Fourier transform on the time-frequency representation subjected to nonlinear diffusion to obtain a singular frequency spectrum; calculating the standard deviation of the energy of the singular spectrum along with the frequency change based on the singular spectrum;calculating the current division number based on the set second threshold rangeWherein->The method comprises the steps of carrying out a first treatment on the surface of the Splitting the current into +.>A sub-current; wherein (1)>Is singular spectrum, ++>Is the angular frequency.
8. The energy storage power distribution and emergency power supply system of claim 7, wherein the method of non-linearly diffusing the time-frequency representation comprises: nonlinear diffusion of the time-frequency representation is performed using the following formula:the method comprises the steps of carrying out a first treatment on the surface of the Wherein (1)>Is a time-frequency representation through nonlinear diffusion; />Is a time-frequency representation; />A center frequency that is a nonlinear diffusion; />Is frequency; />Is time of；/>A nonlinear parameter with a value ranging from 0.3 to 0.7; />For nonlinear adjustment parameters, the value range is 0.25 to 0.56.
9. The energy storage power distribution and emergency power supply system of claim 8, wherein the current time series is normalized using the formula:；
wherein,is a current time series; />Is the normalized current time series.
10. The energy storage power distribution and emergency power supply system according to claim 9, wherein the standard deviation of the energy of the singular spectrum with frequency is calculated using the following formula:wherein (1)>Is a component of angular frequency over the frequency spectrum, +.>Is the frequency sampling point number, < >>Is frequency->Average energy at; />Is the standard deviation of the energy of the singular spectrum with frequency.
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