CN104749434B - Harmonic emission level estimation method based on parameter identification - Google Patents

Abstract

The invention discloses a method for estimating the harmonic emission level based on parameter identification. The method includes: determining the electrical port to be estimated, and setting the order h of the harmonic component; Sampling the voltage and current to obtain the first voltage sampling sequence and the first current sampling sequence; information extraction is performed on the first voltage sampling sequence and the first current sampling sequence to obtain the voltage fundamental wave amplitude, fundamental fundamental frequency, The second voltage sampling sequence and the second current sampling sequence; obtain the voltage correction integral sequence according to the second voltage sampling sequence; obtain the load time-domain equivalent parameters according to the voltage correction integral sequence, the second voltage sampling sequence and the second current sampling sequence, and generate Load time-domain equivalent parameter sequence and calculate its standard deviation; calculate active h-order harmonic current effective value and active h-order harmonic current distortion rate according to the standard deviation. The method is simple and accurate, and is conducive to popularization and application in practical engineering.

Description

Estimation Method of Harmonic Emission Level Based on Parameter Identification

technical field

The invention relates to the technical field of power quality monitoring and analysis of power systems, in particular to a method for estimating harmonic emission levels based on parameter identification.

Background technique

Harmonic pollution is a common power quality problem in distribution networks and microgrids. In recent years, the access of distributed power sources and nonlinear loads has been increasing, making the harmonic problems of public power grids increasingly prominent. In order to effectively control harmonic pollution, it is necessary to clarify the responsibility for harmonic pollution, that is, accurately locate the source of harmonics and evaluate the level of harmonic emissions. The propagation characteristics of harmonics in the power grid are relatively special, and there are interaction and superposition effects, which make it difficult to estimate the level of harmonic emissions. The harmonic emission level estimation method in the related art has certain adaptability problems in terms of use conditions, and the accuracy in practical engineering applications is not satisfactory. The partial harmonic emission level estimation method depends on some system parameters that are inconvenient to measure, so its practicability in actual engineering applications is greatly limited.

Contents of the invention

The present invention aims to solve one of the technical problems in the related art at least to a certain extent. Therefore, the object of the present invention is to propose a method for estimating the harmonic emission level based on parameter identification, which can estimate the harmonic emission level relatively simply and accurately, has wide applicability, and is conducive to popularization and application in practical engineering.

In order to achieve the above object, the harmonic emission level estimation method based on parameter identification in the embodiment of the present invention includes the following steps: S1, determine the electrical port to be estimated, and set the order h of the harmonic component; S2, use the same sampling Sampling the voltage and current on the electrical port to be estimated at intervals to obtain a first voltage sampling sequence and a first current sampling sequence; S3, performing information on the first voltage sampling sequence and the first current sampling sequence Extract to obtain the amplitude of the fundamental voltage, the actual frequency of the fundamental, a second voltage sampling sequence containing only the fundamental component and the h-th harmonic component, and a second current sampling sequence containing only the fundamental component and the h-th harmonic component ; S4. Obtain a voltage correction integral sequence according to the second voltage sampling sequence; S5. Acquire load time-domain equivalent parameters according to the voltage correction integral sequence, the second voltage sampling sequence, and the second current sampling sequence, And generate a load time-domain equivalent parameter sequence according to the load time-domain equivalent parameter, and calculate the standard deviation of the load time-domain equivalent parameter sequence; and S6, calculate the effective active h-th harmonic current according to the standard deviation value and the active hth harmonic current distortion rate to estimate the harmonic emission level of the electrical port.

The harmonic emission level estimation method based on parameter identification in the embodiment of the present invention uses the signal sampling data of the voltage waveform and current waveform to analyze the time-domain equivalent parameters of the load port, and combines the standard deviation of the time-domain equivalent parameters with the harmonic The quantitative relationship between emission levels is used to calculate the harmonic emission level of harmonic sources. This method can estimate the harmonic emission level more easily and accurately, and has wide applicability, which is conducive to popularization and application in practical engineering.

Further, in an embodiment of the present invention, the S3 specifically includes: performing fast Fourier transform on the first voltage sampling sequence and the first current sampling sequence to obtain the voltage fundamental wave amplitude, voltage Fundamental wave phase, current fundamental wave amplitude, current fundamental wave phase, actual frequency of the fundamental wave and voltage hth harmonic amplitude, voltage hth harmonic phase, current hth harmonic amplitude, current hth harmonic Phase: Synthesize the voltage fundamental wave component according to the voltage fundamental wave amplitude and the voltage fundamental wave phase, and synthesize the voltage h order harmonic component according to the voltage h order harmonic amplitude and the voltage h order harmonic phase , and performing an inverse fast Fourier transform on the voltage fundamental component and the voltage hth harmonic component to generate the second voltage sampling sequence; synthesized according to the current fundamental amplitude and the current fundamental phase The current fundamental wave component, and synthesize the current h-order harmonic component according to the current h-order harmonic amplitude and the current h-order harmonic phase, and the current h-order harmonic component and the current h-order harmonic component performing an inverse fast Fourier transform to generate the second current sampling sequence.

Further, in an embodiment of the present invention, the S4 specifically includes: obtaining the fundamental wave phase zero point of the second voltage sampling sequence according to the voltage fundamental wave phase; numerically integrating the second voltage sampling sequence , to generate a voltage original integration sequence; and obtain the voltage correction integration sequence according to the fundamental wave phase zero point and the voltage original integration sequence.

Further, in an embodiment of the present invention, the S5 specifically includes: determining the solution order K, constructing a linear equation according to the voltage correction integration sequence, the second voltage sampling sequence and the second current sampling sequence group; solve the linear equation system to obtain the equivalent parameters of the p-bit K-order load time domain, where K is the solution order, K≥2, p=1,2,...,N,N is the number of sampling points; and generating the load time-domain equivalent parameter sequence according to the p-bit K-order load time-domain equivalent parameter sequence, and calculating the standard deviation of the load time-domain equivalent parameter sequence.

Further, in one embodiment of the present invention, the linear equation system is:

Wherein, u _p is the pth element in the second voltage sampling sequence u ₁ , u ₂ ,...,u _N , and i _p is the second current sampling sequence i ₁ , i ₂ ,..., i _N p elements, y _p is the pth element in the voltage correction integral sequence y ₁ , y ₂ ,...,y _N , r _p and l _p are the load time-domain equivalent parameters of the p-bit K-order, K For the solution order, N is the number of sampling points, and the remainder mod (a, b) of a divided by b is defined as: is less than or equal to largest integer of .

Further, in one embodiment of the present invention, the standard deviation of the load time-domain equivalent parameter sequence is calculated according to the following formula:

in, with are the arithmetic mean values of the load time-domain equivalent parameter sequences r ₁ , r ₂ ,...,r _N and l ₁ , l ₂ ,...,l _N , respectively, and σ _r and σ _l are the load time domain, etc. The standard deviation of the value parameter sequence r ₁ , r ₂ ,...,r _N and l ₁ , l ₂ ,...,l _N , where N is the number of sampling points.

Further, in one embodiment of the present invention, the effective value of the active hth harmonic current and the distortion rate of the active hth harmonic current are calculated according to the following formula:

CHD _ha = I _ha /I ₁ ,

Among them, I _ha is the effective value of the active hth harmonic current, U ₁ is the amplitude of the voltage fundamental wave, σ _r and σ _l are the standard deviations of the load time-domain equivalent parameter sequence, f ₁ is the The actual frequency of the fundamental wave, h is the order of the harmonic component, CHD _ha is the distortion rate of the active h order harmonic current, I ₁ is the amplitude of the current fundamental wave.

Further, in an embodiment of the present invention, the fundamental phase zero point of the second voltage sampling sequence is obtained according to the following formula:

Wherein, S is the zero point of the fundamental wave phase, θ _u1 is the phase of the fundamental wave of the voltage, and L is the number of sampling points for sampling the voltage and current on the electrical port to be estimated in each power frequency fundamental wave period, N is the number of sampling points, round(a) is defined as the integer closest to a, and the remainder mod(a,b) of a divided by b is defined as: is less than or equal to largest integer of .

Further, in an embodiment of the present invention, the voltage correction integral sequence is obtained according to the following formula:

y _k =y _sk -y _sS , k=1,2,...,N,

Wherein, y _k is the kth element of the voltage correction integration sequence, y _sk is the kth element of the voltage original integration sequence, y _sS is the Sth element of the voltage original integration sequence, and S is the The fundamental wave phase zero point, N is the number of sampling points.

Further, in an embodiment of the present invention, the N and the L satisfy the following relationship: N=mL, where m is a positive integer.

Description of drawings

1 is a flowchart of a method for estimating harmonic emission levels based on parameter identification according to an embodiment of the present invention;

Fig. 2 is an information extraction of the first voltage sampling sequence and the first current sampling sequence according to an embodiment of the present invention, to obtain the voltage fundamental wave amplitude, the actual frequency of the fundamental wave, including only the fundamental wave component and the hth harmonic component The flow chart of the second voltage sampling sequence of the second voltage sampling sequence and the second current sampling sequence that only includes the fundamental wave component and the hth harmonic component;

FIG. 3 is a flow chart of obtaining a voltage correction integral sequence according to a second voltage sampling sequence according to an embodiment of the present invention;

Fig. 4 is the time domain equivalent parameters of load obtained according to the voltage correction integration sequence, the second voltage sampling sequence and the second current sampling sequence, and the time domain equivalent parameters of load are generated according to the load time domain equivalent parameters according to an embodiment of the present invention sequence, and a flow chart for calculating the standard deviation of a sequence of equivalent parameters in the load time domain.

detailed description

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

The port equivalent impedance value of ordinary linear load fluctuates less in the power frequency fundamental wave cycle, while the port equivalent impedance value of harmonic source fluctuates greatly in the power frequency fundamental wave cycle. Therefore, the fluctuation of the port equivalent impedance value in the power frequency fundamental cycle can be used to distinguish between ordinary linear loads and harmonic source loads. This method has clear indicators, simple principle, less quantity measurement required, and has strong engineering practicability and application prospect.

Therefore, in order to estimate the level of harmonic emission and clarify the responsibility of harmonic pollution, the present invention is based on the load time-domain equivalent theory, considering the quantitative relationship between the standard deviation of equivalent parameters and the level of harmonic emission, and proposes a method based on parameter identification. Harmonic emission level estimation method. The method for estimating the harmonic emission level based on parameter identification according to the embodiment of the present invention will be described below with reference to the accompanying drawings.

Fig. 1 is a flowchart of a method for estimating harmonic emission levels based on parameter identification according to an embodiment of the present invention. As shown in Figure 1, the harmonic emission level estimation method based on parameter identification in the embodiment of the present invention includes the following steps:

S1, determine the electrical port to be estimated, and set the order h of the harmonic component.

Specifically, first determine the analysis requirements, that is, determine the electrical port that needs to be estimated for the harmonic emission level, and this port is the connection port between the subsystem to be analyzed and the upper-level power grid. The subsystem to be analyzed may be a single load device, or it may be a small and medium-sized power system including multiple loads and generating devices.

Further, the order of the harmonic component that needs to be estimated for the harmonic emission level is determined, and the order of this harmonic component is denoted as h. Limited to the conditions of practical engineering applications, the value of the number h should be within a certain reasonable range, and the typical value is less than 50 times.

S2. Simultaneously sample the voltage and current on the electrical port to be estimated at the same sampling interval to obtain a first voltage sampling sequence and a first current sampling sequence.

In one embodiment of the present invention, N and L satisfy the following relationship: N=mL, wherein, N is the number of sampling points, and L is the voltage and current on the electrical port to be estimated in each cycle of the power frequency fundamental wave. The number of sampling points, m is a positive integer.

Specifically, the voltage waveform and current waveform on the port are sampled at the electrical port to be estimated to obtain the first voltage sampling sequence u _s1 , u _s2 ,..., u _sN and the first current sampling sequence i _s1 , i _s2 , …,i _sN , where N is the number of sampling points.

More specifically, when sampling the voltage and current on the electrical port to be estimated, the following conditions should be met:

1) The sampling of the voltage waveform and the current waveform should be simultaneous, that is, for the corresponding data points u _sk and i _sk in the first voltage sampling sequence and the first current sampling sequence, the sampling time should be the same, where k =1,2,...,N.

2) Sampling should be at equal intervals, that is, the sampling time interval Δt between all two adjacent data points in the first voltage sampling sequence and the first current sampling sequence should be the same.

3) Sampling should be a complete period of sampling, that is, the number of sampling points N and the number of points L corresponding to a power frequency fundamental wave cycle in the first voltage sampling sequence or the first current sampling sequence should satisfy N=mL, where m is a positive integer.

4) The sampling should satisfy the sampling theorem, that is, for the sampling frequency f _s =1/Δt, it should satisfy f _s >2hf _s1 , where f _s1 =50Hz. To ensure reliability and accuracy, f _s >4hf _s1 should be taken in practical engineering applications.

S3. Perform information extraction on the first voltage sampling sequence and the first current sampling sequence to obtain the amplitude of the voltage fundamental wave, the actual frequency of the fundamental wave, the second voltage sampling sequence containing only the fundamental wave component and the h-order harmonic component, and only A second current sampling sequence including the fundamental component and the hth harmonic component.

In one embodiment of the present invention, as shown in FIG. 2, S3 specifically includes:

S31. Perform fast Fourier transform on the first voltage sampling sequence and the first current sampling sequence to obtain the voltage fundamental wave amplitude, voltage fundamental wave phase, current fundamental wave amplitude, current fundamental wave phase, fundamental fundamental wave actual frequency, and voltage h Sub-harmonic amplitude, voltage h-th harmonic phase, current h-th harmonic amplitude, current h-th harmonic phase.

Specifically, fast Fourier transform is performed on the first voltage sampling sequence and the first current sampling sequence to obtain voltage fundamental wave amplitude U ₁ , voltage fundamental wave phase θ _u1 , current fundamental wave amplitude I ₁ , and current fundamental wave phase θ _i1 , the actual frequency f ₁ of the fundamental wave, the voltage h-order harmonic amplitude U _h , the voltage h-order harmonic phase θ _uh , the current h-order harmonic amplitude I _h , and the current h-order harmonic phase θ _ih .

S32, synthesizing the voltage fundamental wave component according to the voltage fundamental wave amplitude and the voltage fundamental wave phase, and synthesizing the voltage h order harmonic component according to the voltage h order harmonic amplitude and the voltage h order harmonic phase, and the voltage fundamental wave component and An inverse fast Fourier transform is performed on the hth harmonic component of the voltage to generate a second voltage sampling sequence.

Specifically, using the inverse fast Fourier transform, the voltage fundamental component (U ₁ , θ _u1 ) and the voltage h-th harmonic component (U _h , θ _uh ) generate the second For the voltage sampling sequence, the second voltage sampling sequence is denoted as u ₁ , u ₂ , . . . , u _N .

S33, synthesizing the current fundamental wave component according to the current fundamental wave amplitude and the current fundamental wave phase, and synthesizing the current h order harmonic component according to the current h order harmonic amplitude and the current h order harmonic phase, and synthesizing the current fundamental wave component and An inverse fast Fourier transform is performed on the hth harmonic component of the current to generate a second current sampling sequence.

Specifically, using the inverse fast Fourier transform, the current fundamental component (I ₁ , θ _i1 ) and the current h-th harmonic component (I _h , θ _ih ) generate the second For the current sampling sequence, the second current sampling sequence is denoted as i ₁ , i ₂ , . . . , i _N .

S4. Acquire a voltage correction integration sequence according to the second voltage sampling sequence.

In one embodiment of the present invention, as shown in FIG. 3, S4 specifically includes:

S41. Acquire the fundamental phase zero point of the second voltage sampling sequence according to the voltage fundamental phase.

In one embodiment of the present invention, the fundamental phase zero point of the second voltage sampling sequence is obtained according to the following formula:

Among them, S is the zero point of the fundamental phase, θ _u1 is the phase of the fundamental voltage, L is the number of sampling points for sampling the voltage and current on the electrical port to be estimated in each cycle of the fundamental wave of power frequency, N is the number of sampling points, round( a) is defined as the integer closest to a, and the remainder mod(a,b) of a divided by b is defined as: is less than or equal to largest integer of .

Specifically, for an integer a, its integer part [a] is defined as the largest integer less than or equal to a, and its rounded round(a) is defined as the nearest integer to a (if there are 2 integers that meet the requirements at the same time, take one of them the smaller absolute value).

S42. Perform numerical integration on the second voltage sampling sequence to generate a voltage original integration sequence.

Specifically, for the second voltage _{sampling sequence u 1} , _{u 2} , .

S43. Obtain a voltage correction integration sequence according to the fundamental wave phase zero point and the original voltage integration sequence.

Specifically, according to the fundamental phase zero point and the original voltage integral sequence, the voltage correction integral sequence y ₁ , y ₂ ,...,y _N is obtained according to the following rules:

y _k =y _sk -y _sS , k=1,2,...,N, (2)

Among them, y _k is the k-th element of the voltage correction integral sequence, y _sk is the k-th element of the original voltage integral sequence, y _sS is the S-th element of the original voltage integral sequence, S is the fundamental phase zero point, and N is Sampling points.

S5, according to the voltage correction integration sequence, the second voltage sampling sequence and the second current sampling sequence to obtain the load time domain equivalent parameters, and according to the load time domain equivalent parameters to generate the load time domain equivalent parameter sequence, and calculate the load time domain, etc. The standard deviation of the sequence of value arguments.

In one embodiment of the present invention, as shown in FIG. 4, S5 specifically includes:

S51. Determine the solution order K, and construct a linear equation system according to the voltage correction integral sequence, the second voltage sampling sequence, and the second current sampling sequence.

Specifically, determine the solution order K, K should be a positive integer, and there should be K≥2. Increasing the value of K helps to improve the stability of the numerical solution and overcome the influence of measurement noise, but it may cause a decrease in the time-domain resolution of the equivalent parameters, a decrease in the solution accuracy, and an increase in the calculation amount of the numerical solution; the typical value of K The value is around 4.

Further, for a positive integer p (p≤N), solution order K (K≥2), second voltage sampling sequence u ₁ , u ₂ ,...,u _N , second current sampling sequence i ₁ , i ₂ , ..., i _N and the voltage correction integral sequence y ₁ , y ₂ , ..., y _N construct a linear equation system according to the following formula (3).

In one embodiment of the present invention, the linear equation system is:

Wherein, u _p is the p-th element in the second voltage sampling sequence u ₁ , u ₂ ,…,u _N , i _p is the p-th element in the second current sampling sequence i ₁ , i ₂ ,…,i _N , y _p is the pth element in the voltage correction integral sequence y ₁ , y ₂ ,…,y _N , K is the solution order, N is the number of sampling points, and the remainder mod(a,b) of dividing a by b is defined as: is less than or equal to The largest integer of , the solutions r _p and l _p of the linear equations (3) are called the equivalent parameters of the p-bit K-order load time domain.

S52, solve the linear equations to obtain all p-bit K-order load time-domain equivalent parameters, where K is the solution order, K≥2, p=1,2,...,N, N is the number of sampling points .

Specifically, for the linear equation system (3), when k=2, solve the linear equation system shown in (3) to obtain the solutions r _p and l _p ; when k>2, solve the solution shown in (3) The overdetermined linear equations are obtained, and the least square solutions r _p and l _p are obtained; the solution results r _p and l _p are the equivalent parameters of the p-bit K-order load in the time domain.

More specifically, all p-bit K-order load time-domain equivalent parameters r _p and l _p are calculated, where p=1, 2, . . . , N, where N is the number of sampling points.

S53. Generate a load time-domain equivalent parameter sequence according to the p-bit K-order load time-domain equivalent parameter sequence, and calculate a standard deviation of the load time-domain equivalent parameter sequence.

Specifically, all the obtained p-bit K-order load time-domain equivalent parameters (p=1, 2,...,N) are composed of load time-domain equivalent parameter sequences r ₁ , r ₂ ,...,r _N and l ₁ ,l ₂ ,…,l _N . And according to the formula (4), calculate the standard deviation of the equivalent parameter sequence r ₁ ,r ₂ ,…,r _N and l ₁ ,l ₂ ,…,l _N in the load time domain.

In one embodiment of the present invention, the standard deviation of the load time-domain equivalent parameter sequence is calculated according to the following formula (4):

in, with are the arithmetic mean values of the load time-domain equivalent parameter sequences r ₁ , r ₂ ,…,r _N and l ₁ ,l ₂ ,…,l _N , respectively, σ _r and σ _l are the load time-domain equivalent parameter sequences r ₁ ,r ₂ ,…,r _N and the standard deviation of l ₁ ,l ₂ ,…,l _N , where N is the number of sampling points.

S6. Calculate the effective value of the active h-order harmonic current and the distortion rate of the active h-order harmonic current according to the standard deviation, so as to estimate the harmonic emission level of the electrical port.

Specifically, the effective value of the active h-order harmonic current I _ha is the effective value of the h-order harmonic current that the electrical port actively injects into the upper-level power grid. This index is one of the indicators for estimating the harmonic emission level, and the harmonic emission Level estimation can evaluate the actual size of the h-order harmonic current emission of the electrical port; the active h-order harmonic current distortion rate CHD _ha is the h-order harmonic current amplitude and the fundamental current amplitude that the electrical port actively injects into the upper-level power grid This indicator is also one of the indicators for estimating the level of harmonic emission. Using this indicator to estimate the level of harmonic emission can evaluate the magnitude of the hth harmonic current emission of the electrical port relative to the fundamental current.

In one embodiment of the present invention, the effective value of the active h-order harmonic current and the distortion rate of the active h-order harmonic current are calculated according to the following formulas (5) and (6):

CHD _ha = I _ha /I ₁ , (6)

Among them, I _ha is the effective value of the active hth harmonic current, U ₁ is the amplitude of the fundamental voltage wave, σ _r and σ _l are the standard deviations of the equivalent parameter sequence in the load time domain, f ₁ is the actual frequency of the fundamental wave, and h is The order of the harmonic component, CHD _ha is the distortion rate of the active hth harmonic current, and I ₁ is the amplitude of the current fundamental wave.

The harmonic emission level estimation method based on parameter identification in the embodiment of the present invention uses the signal sampling data of the voltage waveform and current waveform to analyze the time-domain equivalent parameters of the load port, and combines the standard deviation of the time-domain equivalent parameters with the harmonic The quantitative relationship between emission levels is used to calculate the harmonic emission level of harmonic sources. This method can estimate the harmonic emission level more easily and accurately, and has wide applicability, which is conducive to popularization and application in practical engineering.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Clockwise", "Counterclockwise", "Axial" , "radial", "circumferential" and other indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying the referred device or Elements must have certain orientations, be constructed and operate in certain orientations, and therefore should not be construed as limitations on the invention.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

In the present invention, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection" and "fixation" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , or integrated; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise specified limit. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the present invention, unless otherwise clearly specified and limited, the first feature may be in direct contact with the first feature or the first and second feature may be in direct contact with the second feature through an intermediary. touch. Moreover, "above", "above" and "above" the first feature on the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "beneath" and "beneath" the first feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples" or "some examples" mean specific features described in connection with the embodiment or example, A structure, material or characteristic is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (10)

1. A method for estimating harmonic emission levels based on parameter identification, characterized in that, comprising the following steps: S1. Determine the electrical port to be estimated, and set the order h of the harmonic component; S2. Simultaneously sampling the voltage and current on the electrical port to be estimated at the same sampling interval to obtain a first voltage sampling sequence and a first current sampling sequence; S3. Perform information extraction on the first voltage sampling sequence and the first current sampling sequence to obtain the amplitude of the voltage fundamental wave, the actual frequency of the fundamental wave, and the second voltage sampling sequence including only the fundamental wave component and the h-order harmonic component and a second current sampling sequence comprising only the fundamental component and the hth harmonic component; S4. Obtain a voltage correction integration sequence according to the second voltage sampling sequence; S5. Acquire load time-domain equivalent parameters according to the voltage correction integration sequence, the second voltage sampling sequence, and the second current sampling sequence, and generate load time-domain equivalent parameters according to the load time-domain equivalent parameters sequence, and calculate the standard deviation of the load time-domain equivalent parameter sequence; S6. Calculate the effective value of the active h-order harmonic current and the distortion rate of the active h-order harmonic current according to the standard deviation, so as to estimate the harmonic emission level of the electrical port. 2. The harmonic emission level estimation method based on parameter identification as claimed in claim 1, wherein said S3 specifically comprises: performing fast Fourier transform on the first voltage sampling sequence and the first current sampling sequence to obtain the voltage fundamental wave amplitude, voltage fundamental wave phase, current fundamental wave amplitude, current fundamental wave phase, and the fundamental Actual wave frequency and voltage h-th harmonic amplitude, voltage h-th harmonic phase, current h-th harmonic amplitude, and current h-th harmonic phase; synthesizing a voltage fundamental wave component based on the voltage fundamental wave amplitude and the voltage fundamental wave phase, and synthesizing a voltage h order harmonic component based on the voltage h order harmonic amplitude and the voltage h order harmonic phase, and performing an inverse fast Fourier transform on the voltage fundamental component and the voltage hth harmonic component to generate the second voltage sampling sequence; synthesizing a current fundamental wave component based on the current fundamental wave amplitude and the current fundamental wave phase, and synthesizing a current h order harmonic component based on the current h order harmonic amplitude and the current h order harmonic phase, and performing an inverse fast Fourier transform on the current fundamental component and the current hth harmonic component to generate the second current sampling sequence. 3. The harmonic emission level estimation method based on parameter identification as claimed in claim 2, wherein said S4 specifically comprises: Acquiring the fundamental wave phase zero point of the second voltage sampling sequence according to the voltage fundamental wave phase; numerically integrating the second voltage sampling sequence to generate a voltage original integration sequence; The voltage correction integration sequence is obtained according to the fundamental phase zero point and the voltage original integration sequence. 4. The harmonic emission level estimation method based on parameter identification as claimed in claim 1, wherein said S5 specifically comprises: Determine the solution order K, and construct a linear equation system according to the voltage correction integral sequence, the second voltage sampling sequence and the second current sampling sequence; Solve the linear equations to obtain the load time-domain equivalent parameters of p-bit K order, where K is the solution order, K≥2, p=1,2,...,N, N is the sampling points; generating the load time-domain equivalent parameter sequence according to the p-bit K-order load time-domain equivalent parameter sequence, and calculating the standard deviation of the load time-domain equivalent parameter sequence. 5. the harmonic emission level estimation method based on parameter identification as claimed in claim 4, is characterized in that, described linear equation group is: $\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; mod</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; mod</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\\ \begin{array}{c}<span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\end{array}\\ {\mathrm{<span\; class="notranslate">\; i</span>}}_{\mathrm{<span\; class="notranslate">\; mod</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\end{array}\right]<span\; class="notranslate">\; =</span>\left[\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}& {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; mod</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; mod</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; mod</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; mod</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\\ \begin{array}{c}<span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\end{array}& \begin{array}{c}<span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\\ <span\; class="notranslate">\; .</span>\end{array}\\ {\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; mod</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}& {\mathrm{<span\; class="notranslate">\; the\; y</span>}}_{\mathrm{<span\; class="notranslate">\; mod</span>}<span\; class="notranslate">\; (</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; p</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}\end{array}\right]<span\; class="notranslate">\; \&times;</span>\left[\begin{array}{c}{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\\ {\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; p</span>}}\end{array}\right]<span\; class="notranslate">\; ,</span>$ Wherein, u _p is the pth element in the second voltage sampling sequence u ₁ , u ₂ ,...,u _N , and i _p is the second current sampling sequence i ₁ , i ₂ ,..., i _N p elements, y _p is the pth element in the voltage correction integral sequence y ₁ , y ₂ ,...,y _N , r _p and l _p are the load time-domain equivalent parameters of the p-bit K-order, K For the solution order, N is the number of sampling points, and the remainder mod (a, b) of a divided by b is defined as: is less than or equal to largest integer of . 6. the harmonic emission level estimation method based on parameter identification as claimed in claim 5, is characterized in that, calculates the standard deviation of described load time-domain equivalent parameter sequence according to following formula: $\left\{\begin{array}{c}{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; =</span>\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\\ {\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}}<span\; class="notranslate">\; =</span>\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; N</span>}}\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; N</span>}}{<span\; class="notranslate">\; \&Sigma;</span>}}{<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; l</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; -</span>\stackrel{<span\; class="notranslate">\; \&OverBar;</span>}{\mathrm{<span\; class="notranslate">\; l</span>}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}\end{array}\right.<span\; class="notranslate">\; ,</span>$ in, with are the arithmetic mean values of the load time-domain equivalent parameter sequences r ₁ , r ₂ ,...,r _N and l ₁ , l ₂ ,...,l _N , respectively, and σ _r and σ _l are the load time domain, etc. The standard deviation of the value parameter sequence r ₁ , r ₂ ,...,r _N and l ₁ , l ₂ ,...,l _N , where N is the number of sampling points. 7. The harmonic emission level estimation method based on parameter identification as claimed in claim 6, wherein the effective value of the active hth harmonic current and the distortion rate of the active hth harmonic current are calculated according to the following formula : ${\mathrm{<span\; class="notranslate">\; I</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; r</span>}}<span\; class="notranslate">\; +</span>\frac{{\mathrm{<span\; class="notranslate">\; \&sigma;</span>}}_{\mathrm{<span\; class="notranslate">\; l</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&pi;f</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; )</span>}{\sqrt{{\mathrm{<span\; class="notranslate">\; h</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; ,</span>$ CHD _ha = I _ha /I ₁ , Wherein, I _ha is the effective value of the active hth harmonic current, U ₁ is the amplitude of the fundamental voltage wave, σ _r and σ _l are the load time-domain equivalent parameter sequences r ₁ , r ₂ ,… , r _N and the standard deviation of l ₁ , l ₂ ,...,l _N , N is the number of sampling points, f ₁ is the actual frequency of the fundamental wave, h is the order of the harmonic component, CHD _ha is the Active h-order harmonic current distortion rate, I ₁ is the amplitude of the current fundamental wave. 8. the harmonic emission level estimation method based on parameter identification as claimed in claim 3, is characterized in that, obtains the fundamental wave phase zero point of described second voltage sampling sequence according to following formula: $\mathrm{<span\; class="notranslate">\; S</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; mod</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; r</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; no</span>}\mathrm{<span\; class="notranslate">\; d</span>}<span\; class="notranslate">\; (</span>\frac{<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&theta;</span>}}_{\mathrm{<span\; class="notranslate">\; u</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}}\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; N</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span>$ Wherein, S is the zero point of the fundamental wave phase, θ _u1 is the phase of the fundamental wave of the voltage, and L is the number of sampling points for sampling the voltage and current on the electrical port to be estimated in each power frequency fundamental wave period, N is the number of sampling points, round(a) is defined as the integer closest to a, and the remainder mod(a,b) of a divided by b is defined as: is less than or equal to largest integer of . 9. The harmonic emission level estimation method based on parameter identification as claimed in claim 8, wherein the voltage correction integral sequence is obtained according to the following formula: y _k =y _sk -y _sS , k=1,2,...,N, Wherein, y _k is the kth element of the voltage correction integration sequence, y _sk is the kth element of the voltage original integration sequence, y _sS is the Sth element of the voltage original integration sequence, and S is the The fundamental wave phase zero point, N is the number of sampling points. 10. The method for estimating harmonic emission levels based on parameter identification according to claim 8, wherein said N and said L satisfy the following relationship: N=mL, wherein m is a positive integer.