CN105223419B

CN105223419B - The all phase difference detection method and system of electric power signal

Info

Publication number: CN105223419B
Application number: CN201510599189.5A
Authority: CN
Inventors: 李军; 陈世和; 万文军; 罗嘉; 庞志强
Original assignee: Electric Power Research Institute of Guangdong Power Grid Co Ltd
Current assignee: Electric Power Research Institute of Guangdong Power Grid Co Ltd
Priority date: 2015-09-18
Filing date: 2015-09-18
Publication date: 2017-11-14
Anticipated expiration: 2035-09-18
Also published as: CN105223419A

Abstract

The present invention relates to all phase difference detection method and system of a kind of electric power signal.The present invention obtains zero initial phase cosine function modulation sequence and zero initial phase SIN function modulation sequence by sequence of operations, then selects the larger modulation sequence of average amplitude as zero initial phase modulation sequence for the signal sequence of any initial phase.The zero initial phase modulation sequence avoids the influence of any initial phase problem of signal sequence, zero initial phase modulation sequence carries the larger signal sequence all phase difference information of numerical value simultaneously, can significantly improve the degree of accuracy of sine parameter calculating, improve anti-harmonic wave and noise jamming.The all phase difference degree of accuracy for the electric power signal that the present invention obtains according to the zero initial phase modulation sequence can reach 10^‑10Magnitude, the degree of accuracy that all phase difference calculates are higher.

Description

Full phase difference detection method and system for power signals

Technical Field

The present invention relates to the field of power technologies, and in particular, to a method and a system for detecting a total phase difference of a power signal.

Background

Measurements of sinusoidal parameters of the power system include frequency measurements, phase measurements, amplitude measurements, and the like. The Fourier transform is a basic method for realizing sinusoidal parameter measurement and has wide application in power systems. However, with the development of sinusoidal parameter measurement technology, the problems of fourier transform are more prominent, and it is difficult to further meet the requirement of the power system on high accuracy calculation of sinusoidal parameters.

In the aspect of measuring sinusoidal parameters of the power system, there are some improved parameter measuring methods, such as a zero-crossing method, a filter-based measuring method, a wavelet transform-based measuring method, a neural network-based measuring method, a DFT (Discrete fourier transform) -transform-based measuring method, and the like. The rated power frequency of the power grid is near 50Hz (hertz), and the frequency is low sinusoidal. Due to the limitations of the actual signal processing technology and the complexity of signal composition, such as the influence of data quantization background noise generated by signal discrete sampling, the problem of frequency spectrum leakage caused by signal sequence truncation is objectively difficult to avoid, the influence of any initial phase problem of signals, the influence of direct current, sub-harmonic and subharmonic problems in signals and the like, the measurement precision of the algorithms is low, and the harmonic and noise interference resistance is poor.

Disclosure of Invention

In view of the foregoing, it is desirable to provide a method and a system for detecting a full phase difference of an electric power signal, which can improve accuracy of sinusoidal parameter calculation and improve harmonic and noise immunity.

In order to solve the technical problems, the invention adopts the following technical scheme:

a method of detecting a full phase difference of a power signal, comprising the steps of:

obtaining a preliminary sampling sequence length according to the lower limit of the power signal frequency range, a preset sampling frequency and a preset integer signal period number;

performing preliminary sampling on the electric power signal according to the length of the preliminary sampling sequence to obtain a preliminary sampling sequence of the electric power signal;

carrying out frequency initial measurement on the initial sampling sequence to obtain an initial frequency of the power signal, and determining a reference frequency according to the initial frequency;

obtaining the unit cycle sequence length of the power signal according to the preset sampling frequency and the reference frequency;

obtaining a preset sequence length according to the preset integer signal period number and the unit period sequence length;

acquiring a forward sequence from the preliminary sampling sequence according to the preset sequence length;

reversely outputting the forward sequence to obtain a reverse pleat sequence of the forward sequence;

adding the forward sequence and the reverse pleat sequence to obtain a zero initial phase cosine function modulation sequence;

subtracting the forward sequence and the reverse pleat sequence to obtain a zero initial phase sine function modulation sequence;

performing integral operation on the absolute value of the zero initial phase cosine function modulation sequence to obtain a first average amplitude of the zero initial phase cosine function modulation sequence;

performing integral operation on the absolute value of the zero initial phase sine function modulation sequence to obtain a second average amplitude of the zero initial phase sine function modulation sequence;

judging whether the first average amplitude is larger than or equal to the second average amplitude, if so, taking the zero initial phase cosine function modulation sequence as a zero initial phase modulation sequence, and if not, taking the zero initial phase sine function modulation sequence as a zero initial phase modulation sequence;

truncating the zero initial phase modulation sequence to obtain a truncated sequence;

multiplying the cosine function of the reference frequency and the sine function of the reference frequency with the zero initial phase modulation sequence respectively to obtain a first real frequency vector sequence and a first virtual frequency vector sequence;

multiplying the cosine function of the reference frequency and the sine function of the reference frequency with the truncated sequence respectively to obtain a second real frequency vector sequence and a second virtual frequency vector sequence;

respectively carrying out digital notch on the first real frequency vector sequence and the first virtual frequency vector sequence to obtain a first real frequency vector notch sequence and a first virtual frequency vector notch sequence;

respectively carrying out integral operation on the first real frequency vector notch sequence and the first virtual frequency vector notch sequence to obtain a first real frequency vector integral value and a first virtual frequency vector integral value;

respectively carrying out digital notch on the second real frequency vector sequence and the second virtual frequency vector sequence to obtain a second real frequency vector notch sequence and a second virtual frequency vector notch sequence;

respectively carrying out integral operation on the second real frequency vector notch sequence and the second virtual frequency vector notch sequence to obtain a second real frequency vector integral value and a second virtual frequency vector integral value;

converting the first imaginary frequency vector integral value and the first real frequency vector integral value into a first phase according to a preset phase conversion rule; converting the second imaginary frequency vector integral value and the second real frequency vector integral value into a second phase;

converting the first phase and the second phase into an initial phase of the zero initial phase modulation sequence according to a preset initial phase conversion rule;

and converting the initial phase of the zero initial phase modulation sequence into the full phase difference of the electric power signal according to a preset full phase difference conversion rule.

A system for full phase difference detection of a power signal, comprising:

the preliminary sampling sequence length determining module is used for obtaining the preliminary sampling sequence length according to the lower limit of the power signal frequency range, the preset sampling frequency and the preset integer signal period number;

the preliminary sampling sequence acquisition module is used for preliminarily sampling the electric power signal according to the length of the preliminary sampling sequence to acquire a preliminary sampling sequence of the electric power signal;

a reference frequency determining module, configured to perform frequency initial measurement on the initial sampling sequence, obtain an initial frequency of the power signal, and determine a reference frequency according to the initial frequency;

the unit cycle sequence length determining module is used for obtaining the unit cycle sequence length of the power signal according to the preset sampling frequency and the reference frequency;

the preset sequence length determining module is used for obtaining the length of a preset sequence according to the number of the preset integer signal cycles and the length of the unit cycle sequence;

a forward sequence obtaining module, configured to obtain a forward sequence from the preliminary sampling sequence according to the preset sequence length;

the reverse pleat sequence acquisition module is used for reversely outputting the forward sequence to acquire a reverse pleat sequence of the forward sequence;

a cosine function modulation sequence determining module, configured to add the forward sequence and the inverse pleat sequence to obtain a zero initial phase cosine function modulation sequence;

the sine function modulation sequence determining module is used for subtracting the forward sequence from the reverse pleat sequence to obtain a zero initial phase sine function modulation sequence;

the first average amplitude determining module is used for performing integral operation on the absolute value of the zero initial phase cosine function modulation sequence to obtain a first average amplitude of the zero initial phase cosine function modulation sequence;

the second average amplitude determining module is used for performing integral operation on the absolute value of the zero initial phase sine function modulation sequence to obtain a second average amplitude of the zero initial phase sine function modulation sequence;

an average amplitude judgment module, configured to judge whether the first average amplitude is greater than or equal to the second average amplitude, when the first average amplitude is greater than or equal to the second average amplitude, use the zero initial phase cosine function modulation sequence as a zero initial phase modulation sequence, and when the first average amplitude is smaller than the second average amplitude, use the zero initial phase sine function modulation sequence as a zero initial phase modulation sequence;

a truncated sequence obtaining module, configured to truncate the zero initial phase modulation sequence to obtain a truncated sequence;

a first vector sequence determining module, configured to multiply the cosine function of the reference frequency and the sine function of the reference frequency with the zero initial phase modulation sequence, respectively, to obtain a first real frequency vector sequence and a first imaginary frequency vector sequence;

a second vector sequence determining module, configured to multiply the cosine function of the reference frequency and the sine function of the reference frequency with the truncated sequence, respectively, to obtain a second real frequency vector sequence and a second imaginary frequency vector sequence;

a first notch sequence determining module, configured to perform digital notch on the first real frequency vector sequence and the first virtual frequency vector sequence, respectively, to obtain a first real frequency vector notch sequence and a first virtual frequency vector notch sequence;

the first integral value determining module is used for respectively carrying out integral operation on the first real frequency vector notch sequence and the first virtual frequency vector notch sequence to obtain a first real frequency vector integral value and a first virtual frequency vector integral value;

a second notch sequence determining module, configured to perform digital notch on the second real frequency vector sequence and the second virtual frequency vector sequence, respectively, to obtain a second real frequency vector notch sequence and a second virtual frequency vector notch sequence;

a second integral value determining module, configured to perform integral operation on the second real frequency vector notch sequence and the second virtual frequency vector notch sequence, respectively, to obtain a second real frequency vector integral value and a second virtual frequency vector integral value;

a phase determining module, configured to convert the first imaginary frequency vector integrated value and the first real frequency vector integrated value into a first phase according to a preset phase conversion rule; converting the second imaginary frequency vector integral value and the second real frequency vector integral value into a second phase;

an initial phase determining module, configured to convert the first phase and the second phase into an initial phase of the zero initial phase modulation sequence according to a preset initial phase conversion rule;

and the full phase difference determining module is used for converting the initial phase of the zero initial phase modulation sequence into the full phase difference of the electric power signal according to a preset full phase difference conversion rule.

The invention discloses a method and a system for detecting the total phase difference of electric power signals. The zero initial phase modulation sequence avoids the influence of any initial phase problem of the signal sequence, and simultaneously carries the signal sequence full phase difference information with larger numerical value, so that the accuracy of sine parameter calculation can be obviously improved, and the harmonic wave and noise interference resistance can be improved. The accuracy of the full phase difference of the power signal obtained according to the zero initial phase modulation sequence can reach 10^-10And the accuracy of the calculation of the full phase difference is higher.

Drawings

FIG. 1 is a schematic flow chart illustrating an embodiment of a method for detecting a full phase difference of an electrical signal according to the present invention;

FIG. 2 is a schematic representation of the lengths of the forward and reverse pleat sequences of the present invention;

FIG. 3 is a schematic diagram of the experimental results of the total phase difference detection relative error obtained by the method of the present invention;

FIG. 4 is a schematic structural diagram of an embodiment of a system for detecting a full phase difference of an electrical signal according to the present invention;

FIG. 5 is a schematic structural diagram of a first embodiment of a phase determination module according to the present invention;

fig. 6 is a schematic structural diagram of a second phase determination module according to an embodiment of the present invention.

Detailed Description

In order to better understand the technical problems to be solved, the technical solutions adopted and the technical effects achieved by the present invention, the following detailed description of the embodiments of the present invention is provided with reference to the accompanying drawings.

As shown in fig. 1, a method for detecting a full phase difference of an electric power signal includes the steps of:

s101, obtaining a preliminary sampling sequence length according to a lower limit of a power signal frequency range, a preset sampling frequency and a preset integer signal cycle number;

s102, performing preliminary sampling on the electric power signal according to the length of the preliminary sampling sequence to obtain a preliminary sampling sequence of the electric power signal;

s103, carrying out frequency initial measurement on the initial sampling sequence, acquiring the initial frequency of the power signal, and determining a reference frequency according to the initial frequency;

s104, obtaining the unit cycle sequence length of the power signal according to the preset sampling frequency and the reference frequency;

s105, obtaining a preset sequence length according to the preset integer signal period number and the unit period sequence length;

s106, acquiring a forward sequence from the preliminary sampling sequence according to the preset sequence length;

s107, reversely outputting the forward sequence to obtain a reverse pleat sequence of the forward sequence;

s108, adding the forward sequence and the reverse pleat sequence to obtain a zero initial phase cosine function modulation sequence;

s109, subtracting the forward sequence and the reverse pleat sequence to obtain a zero initial phase sine function modulation sequence;

s110, performing integral operation on the absolute value of the zero initial phase cosine function modulation sequence to obtain a first average amplitude of the zero initial phase cosine function modulation sequence;

s111, performing integral operation on the absolute value of the zero initial phase sine function modulation sequence to obtain a second average amplitude of the zero initial phase sine function modulation sequence;

s112, judging whether the first average amplitude is larger than or equal to the second average amplitude, if so, taking the zero initial phase cosine function modulation sequence as a zero initial phase modulation sequence, otherwise, taking the zero initial phase sine function modulation sequence as a zero initial phase modulation sequence;

s113, truncating the zero initial phase modulation sequence to obtain a truncated sequence;

s114, multiplying the cosine function of the reference frequency and the sine function of the reference frequency with the zero initial phase modulation sequence respectively to obtain a first real frequency vector sequence and a first imaginary frequency vector sequence;

s115, multiplying the cosine function of the reference frequency and the sine function of the reference frequency with the truncated sequence respectively to obtain a second real frequency vector sequence and a second virtual frequency vector sequence;

s116, respectively carrying out digital notch on the first real frequency vector sequence and the first virtual frequency vector sequence to obtain a first real frequency vector notch sequence and a first virtual frequency vector notch sequence;

s117, respectively carrying out integral operation on the first real frequency vector notch sequence and the first virtual frequency vector notch sequence to obtain a first real frequency vector integral value and a first virtual frequency vector integral value;

s118, respectively carrying out digital notch on the second real frequency vector sequence and the second virtual frequency vector sequence to obtain a second real frequency vector notch sequence and a second virtual frequency vector notch sequence;

s119, respectively carrying out integral operation on the second real frequency vector notch sequence and the second virtual frequency vector notch sequence to obtain a second real frequency vector integral value and a second virtual frequency vector integral value;

s120, converting the first virtual frequency vector integral value and the first real frequency vector integral value into a first phase according to a preset phase conversion rule; converting the second imaginary frequency vector integral value and the second real frequency vector integral value into a second phase;

s121, converting the first phase and the second phase into an initial phase of the zero initial phase modulation sequence according to a preset initial phase conversion rule;

and S122, converting the initial phase of the zero initial phase modulation sequence into the full phase difference of the electric power signal according to a preset full phase difference conversion rule.

The power signal is a sinusoidal signal with a dominant fundamental component. The sine signal is broadly referred to as sine function signal and cosine function signal. The frequency range of the power signal is generally 45Hz to 55 Hz. So that the lower limit f of the frequency range of the power signal_minMay be taken to be 45 Hz. Presetting integer signal period number C_2πThe setting may be made according to actual needs, for example, 11. In one embodiment, the preliminary sample sequence length N may be determined according to equation (1)_start：

Wherein (int) represents rounding; f. of_nIs a preset sampling frequency with the unit of Hz; n is a radical of_startUnit of (a) is dimensionless, C_2πUnit of (a) is dimensionless, f_minIn Hz.

And after the length of the preliminary sampling sequence is obtained, preliminarily sampling the power signal according to the length of the preliminary sampling sequence. For example, the power signal is a single fundamental frequency sinusoidal signal, the single fundamental frequency sinusoidal signal is preliminarily sampled according to the length of the preliminary sampling sequence, and the preliminary sampling sequence X of the power signal is obtained_start(n) is formula (2):

wherein, A is signal amplitude, and the unit can be v; omega is signal frequency, and the unit is rad/s; t is_nIs the sampling interval, with the unit of s; f. of_nIs a preset sampling frequency with the unit of Hz; n is a discrete number of sequences, and the unit is dimensionless;is the initial phase of the signal, and the unit is rad; n is a radical of_startThe unit is dimensionless for the preliminary sample sequence length.

After the preliminary sampling sequence is obtained, the preliminary frequency omega can be obtained by carrying out frequency preliminary measurement on the preliminary sampling sequence through a zero-crossing method, a filtering-based algorithm, a wavelet transform algorithm, a neural network-based algorithm, a DFT (discrete Fourier transform) -based frequency algorithm or a phase difference-based frequency algorithm and the like_oPreliminary frequency ω_oIn units of rad/s. In one embodiment, the preliminary frequency may be used as a reference frequency, i.e., reference frequency ω_sω o. Reference frequency omega_sThe unit is rad/s.

Having obtained the reference frequency, in one embodiment, the unit period sequence length N may be determined according to equation (3)_2π：

Wherein (int) is an integer; f. of_nIs a preset sampling frequency with the unit of Hz; f. of_sReference frequency, ω, in Hz_sReference frequency in rad/s units; n is a radical of_2πThe unit of (a) is dimensionless. The sequence length integer quantization per unit period has an error within 1 sampling interval.

Having obtained the sequence length per unit period, in one embodiment, the predetermined sequence length N is determined according to equation (4):

N＝(int)(C_2πN_2π) (4)

wherein (int) is an integer; the unit of N is dimensionless. From equation (4), the predetermined sequence length N and the integer number of signal periods C_2πAnd (7) corresponding. The predetermined sequence length N may be a unit period sequence length N_2π11 times higher than the original value. The predetermined sequence length includes an integer number of signal periods that is approximate due to errors.

And after the preset series length N is obtained, acquiring a forward sequence from the preliminary sampling sequence according to the preset sequence length. In one embodiment, the forward sequence X obtained by the present invention is based on the preliminary sampling sequence obtained by equation (2)_i(n) is formula (5):

wherein, X_start(n) is a preliminary sampling sequence; a is the signal amplitude, and the unit can be v; omega is signal frequency, and the unit is rad/s; t is_nIs the sampling interval, with the unit of s; n is a discrete number of sequences, and the unit is dimensionless;is the initial phase of the signal, and the unit is rad; n is the length of the forward sequence, i.e. the length of the predetermined sequence, in unitsAnd no dimension is required.

Reverse pleated sequence X of the invention based on the forward sequence obtained in formula (5)_-i(-n) is formula (6):

wherein β is an inverse convolution sequence initial phase, and the inverse convolution sequence initial phase is a cut-off phase of a forward sequence, namely the cut-off phase of the power signal, and the unit is rad; and N is the length of the reverse pleat sequence, and as shown in FIG. 2, the length of the reverse pleat sequence is the same as that of the forward sequence, and the unit is dimensionless.

Based on the forward sequence of the formula (5) and the inverse pleat sequence obtained by the formula (6), the zero initial phase cosine function modulation sequence X obtained by the invention_cos(n) is formula (7):

wherein,modulating the sequence amplitude for the cosine function, wherein the unit can be v;the initial phase of the cosine function modulated sequence is given in rad. The zero initial phase cosine function modulation sequence carriesAnd (4) information.

Because the length of the preset sequence has an error corresponding to the number of the preset integer signal cycles, one reason is the error caused by the error of the reference frequency, and the other reason is the integer error of the length of the preset sequence. If the error is zero, the cosine function modulates the initial phase of the sequenceZero, otherwise cosine function modulates the initial phase of the sequenceAround zero. The initial phaseThe error compared with the zero value is in a direct proportion relation with the error of the preset integer signal period number.

Based on the forward sequence of the formula (5) and the inverse pleat sequence obtained by the formula (6), the zero initial phase sine function modulation sequence X obtained by the invention_sin(n) is formula (8):

wherein,the amplitude of the sine function modulation sequence with zero initial phase can be in v;the initial phase of the sequence is modulated by a zero initial phase sine function, with the unit being rad.

Because the length of the preset sequence has an error corresponding to the number of integer signal cycles, one reason is the error caused by the error of the reference frequency, and the other reason is the integer error of the length of the preset sequence. If the error is zero, the initial phase of the zero initial phase sine function modulation sequenceIs zero, otherwise the initial phaseAround zero. The initial phaseThe error compared to a zero value is proportional to the error for the integer number of signal cycles.

When the initial phase of the signal is arbitrarily changed, the sequence X_cos(n) and X_sin(n) and the situation of zero amplitude may occur, due to the amplitudeAndare in a complementary relationship, and can therefore be derived from the sequence X_cos(n) and the sequence X_sinSelecting the one with larger amplitude as the zero initial phase modulation sequence, and if the amplitudes of the 2 sequences are the same, then selecting the sequence X_cos(n) as a zero initial phase modulation sequence.

In one embodiment, the first average amplitude V is obtained according to equation (9)_cos-avg：

Wherein the first average amplitude V_cos-avgThe unit of (d) may be v; n is a predetermined sequence length, X_cosAnd (n) is a zero initial phase cosine function modulation sequence.

In one embodiment, the second average amplitude V is obtained according to equation (10)_sin-vag：

Wherein the second average amplitude V_sin-vagThe unit of (d) may be v; n is a predetermined sequence length, X_sinAnd (n) is a zero initial phase sine function modulation sequence.

Obtaining a first average amplitude V_cos-avgAnd a secondAverage amplitude V_sin-vagThen, the sizes of the two are compared. When the first average amplitude V is as shown in equation (11)_cos-avgGreater than or equal to the second average amplitude value V_sin-vagTaking the zero initial phase cosine function modulation sequence as a zero initial phase modulation sequence; when the first average amplitude V_cos-avgLess than the second average amplitude V_sin-vagAnd taking the zero initial phase sine function modulation sequence as a zero initial phase modulation sequence.

Wherein, in the formula, X_outAnd (n) is a zero initial phase modulation sequence.

After obtaining the zero initial phase modulation sequence, truncating the zero initial phase modulation sequence as shown in formula (12) to obtain a truncated sequence, wherein the length of truncation may be the length N of the unit period sequence_2π0.25 times of:

wherein, X_s(n) is a truncated sequence; n is the zero initial phase modulation sequence length of a dimensionless unit, namely the length of a preset sequence; n is a radical of_sTruncated sequence length in dimensionless units; m_sThe unit is dimensionless relative to the shortened value of the zero initial phase modulation sequence length; n is a radical of_2πThe length of the unit period sequence in dimensionless units.

Taking the zero initial phase modulation sequence as the zero initial phase cosine function modulation sequence as an example, when the frequency mixing interference frequency component is not considered, the obtained first real frequency vector sequence R₁(n) and a first sequence of imaginary frequency vectors I₁(n) is formula (13):

in the formula, A_cosThe amplitude of the zero initial phase cosine function modulation sequence can be in v.

Taking the zero initial phase modulation sequence as the zero initial phase cosine function modulation sequence as an example, when the frequency mixing interference frequency component is not considered, the obtained second real frequency vector sequence R₂(n) and a second sequence of imaginary frequency vectors I₂(n) is formula (14):

The real frequency vector sequence and the virtual frequency vector sequence contain mixed frequency interference frequencies. When the input signal contains dc component, sub-harmonic component and sub-harmonic component, the mixing interference frequency will be more complex, and the mixing interference frequency will seriously affect the accuracy of frequency calculation. Although the window function and the integral operation have good attenuation effect on the mixing interference frequency, the window function and the integral operation have no pertinence, cannot generate deep inhibition effect on the complex mixing interference frequency, and cannot meet the requirement of high-accuracy calculation of sinusoidal parameters.

In order to specifically suppress the influence of the mixing interference frequency, the invention uses a digital wave trap. Ideally, the zero amplitude frequency point of the digital trap filter exactly corresponds to the mixed interference frequency point, and has a complete suppression effect on the mixed interference frequency. In one embodiment, the digital notch specifically adopts an arithmetic mean filtering algorithm, i.e., a plurality of continuous discrete values are added, and then the arithmetic mean value is taken as the current filtering value to be output. The digital notching requires setting a digital notching parameter, wherein the digital notching parameter refers to the length N of adding a plurality of continuous discrete values_D. At a digital notch parameter N_DWhen the value is 1.5 times of the length of the unit period sequence, the frequency of the mixing interference generated by 1/3 subharmonic can be adjustedAnd (4) line suppression. And N is_DWhen the value is 2 times of the length of the unit period sequence, the mixing interference frequency generated by direct current, 1/2 fractional order, 1 order, 2 order, 3 order, 4 order, 5 order harmonic waves and the like can be suppressed. Therefore, the digital trap consists of 2 kinds of parameter digital traps, and in consideration of factors such as errors, each parameter digital trap consists of three stages of digital traps with the same parameters for deeply suppressing the influence of the mixing interference frequency, and the total number of the digital traps is six stages of arithmetic mean value digital traps. In one embodiment, the six-level arithmetic mean digital trap may be of formula (15):

wherein, X (N) is a digital notch input sequence with a sequence length N; x_D(N) is a digital notch output sequence with a sequence length of N-3N_D1-3N_D2；N_D1The notch parameter 1 is the added number of continuous discrete values; n is a radical of_D2The number of added successive discrete values of the notch parameter 2.

In one embodiment, the notching parameter N_D1A value of 1.5 times the length of the unit period sequence of the reference frequency, and a notch parameter N_D2Taking the value of 2 times the length of the unit period sequence of the reference frequency, a six-level arithmetic mean digital notch requires the use of 10.5 times the length of the unit period sequence.

Taking the zero initial phase modulation sequence as an example of a zero initial phase cosine function modulation sequence, on the premise that the frequency mixing interference frequency component is completely suppressed, the first real frequency vector notch sequence and the first imaginary frequency vector notch sequence are (16):

wherein R is_D1(n) is a first real frequency vector notch sequence; i is_D1(n) is a first virtual frequency vector notch sequenceK (omega) is the dimensionless gain of the digital notch at the frequency difference omega, and α (omega) is the rad unit phase shift of the digital filtering at the frequency difference omega.

Similarly, taking the zero initial phase modulation sequence as an example of a zero initial phase cosine function modulation sequence, on the premise that the frequency mixing interference frequency component is completely suppressed, the second real frequency vector notch sequence and the second imaginary frequency vector notch sequence are expressed by formula (17):

wherein R is_D2(n) is the second real frequency vector notch sequence; i is_D2And (n) is the second imaginary frequency vector notch sequence, K (omega) is the dimensionless gain of the digital filtering at the frequency difference omega, and α (omega) is the phase shift of the digital filtering at the frequency difference omega, and the unit is rad.

In one embodiment, the present invention uses an integrator as known in the art to perform the integration operation. Taking the modulation sequence of the zero initial phase as the modulation sequence of the zero initial phase cosine function as an example, performing integration operation on the first real frequency vector notch sequence and the first imaginary frequency vector notch sequence by using an integrator to obtain a first real frequency vector integral value and a first imaginary frequency vector integral value, which are expressed by the following formula (18):

wherein R is₁Is the first real frequency vector integral value; i is₁Is the first virtual frequency vector integral value; l1 is the integrated calculated length 1 in dimensionless units, L1 is 0.5 times the unit period sequence length.

Similarly, taking the zero initial phase modulation sequence as an example of a zero initial phase cosine function modulation sequence, respectively performing integration operation on the second real frequency vector notch sequence and the second imaginary frequency vector notch sequence by using an integrator to obtain a second real frequency vector integral value and a second imaginary frequency vector integral value, which are expressed by the following formula (19):

wherein R is₂The integral value of the second real frequency vector is obtained; i is₂Is the second imaginary frenquency vector integral value. L2 is the integral calculation length 2 in dimensionless units, L2 is 0.25 times the unit period sequence length.

When the first phase and the second phase are obtained according to a preset phase conversion rule, whether the zero initial phase modulation sequence is a zero initial phase cosine function modulation sequence or a zero initial phase sine function modulation sequence needs to be considered. If the zero initial phase modulation sequence is the zero initial phase cosine function modulation sequence, step S120 may include:

determining a first ratio of the first imaginary eigenvector integrated values to the first real eigenvector integrated values;

taking the inverse of the arctangent function value of the first ratio as the first phase;

determining a second ratio of the second imaginary eigenvector integrated values to the second real eigenvector integrated values;

the second phase is the inverse of the arctan function of the second ratio.

As shown in equations (20) and (21), when the zero initial phase modulation sequence is the zero initial phase cosine function modulation sequence, the obtained first phase and second phase are respectively:

wherein the pH is₁Is the first phase, in rad; r₁Is the first real frequency vector integral value; i is₁Is the first virtual frequency vector integral value; PH value₂Is the second phase, with unit rad; r₂The integral value of the second real frequency vector is obtained; i is₂Is the second imaginary frenquency vector integral value.

If the zero initial phase modulation sequence is the zero initial phase sine function modulation sequence, step S120 may include:

determining a third ratio of the first real frequency vector integral value to the first imaginary frequency vector integral value;

taking an arctangent function value of the third ratio as the first phase;

determining a fourth ratio of the second real frequency vector integral value to the second imaginary frequency vector integral value;

taking an arctan function value of the fourth ratio as the second phase.

It should be noted that the first ratio, the second ratio, the third ratio and the fourth ratio are only used for distinguishing the ratios, and the order of the values is not limited.

As shown in equations (22) and (23), when the zero initial phase modulation sequence is the zero initial phase sine function modulation sequence, the obtained first phase and second phase are respectively:

having obtained the first phase and the second phase, in one embodiment, the initial phase of the zero initial phase modulation sequence may be determined according to equation (24)

The full phase difference of the power signal is the product of the sinusoidal frequency of the signal and the time length of the zero initial phase modulation sequence, the full phase difference △ PH and the initial phaseThe relationship of (1) is: initial phaseEssentially representing an error value of said predetermined sequence length with respect to said integer signal period number, if the error value is zero, said full phase difference is an integer multiple of 2 pi, otherwise said full phase difference is not an integer multiple of 2 pi, the initial phaseThe inverse of the multiples reflects both exactly 2 pi integral multiples and error values other than 2 pi integral multiples.

In one embodiment, the full phase difference Δ PH of the power signal may be determined according to equation (25):

wherein, 2 pi C_2πA full phase difference that is an integral multiple of 2 pi; when C is present_2πWhen equal to 11, 2 π C_2π22 pi, △ PH ranges around 22 pi in rad.

In order to better understand the technical effects achieved by the technical solutions of the present invention, a specific embodiment is described below.

Assuming that an experimental signal is given as equation (26):

the variation range of the fundamental frequency of the signal is 45Hz-55Hz, the number of the integer signal cycles is about 11, the arbitrary initial phase of the signal is provided, the sampling frequency of the signal is 10kHz, the quantization bit number of the discrete data of the signal is 24bit, and the relative error of the initial frequency measurement is provided<Obtaining absolute value | △ PH of signal total phase difference detection relative error | of +/-0.25% |_err(f) Fig. 3 shows a graph of the experimental result of the characteristics of | depending on the frequency f of the fundamental wave of the signal. As can be seen from FIG. 3, the full phase difference detection accuracy of the experimental signal provided by the invention is 10^-10And the accuracy is higher.

Based on the same inventive concept, the invention also provides a system for detecting the full phase difference of the power signal, and the following describes the specific implementation of the system in detail with reference to the accompanying drawings.

As shown in fig. 4, a system for detecting a full phase difference of a power signal includes:

the preliminary sampling sequence length determining module 101 is configured to obtain a preliminary sampling sequence length according to a lower limit of a power signal frequency range, a preset sampling frequency, and a preset integer signal cycle number;

a preliminary sampling sequence obtaining module 102, configured to perform preliminary sampling on the power signal according to the length of the preliminary sampling sequence, and obtain a preliminary sampling sequence of the power signal;

a reference frequency determining module 103, configured to perform frequency initial measurement on the preliminary sampling sequence, obtain a preliminary frequency of the power signal, and determine a reference frequency according to the preliminary frequency;

a unit cycle sequence length determining module 104, configured to obtain a unit cycle sequence length of the power signal according to the preset sampling frequency and the reference frequency;

a preset sequence length determining module 105, configured to obtain a preset sequence length according to the preset integer signal cycle number and the unit cycle sequence length;

a forward sequence obtaining module 106, configured to obtain a forward sequence from the preliminary sampling sequence according to the preset sequence length;

an inverse-convolution sequence obtaining module 107, configured to reversely output the forward sequence to obtain an inverse-convolution sequence of the forward sequence;

a cosine function modulation sequence determining module 108, configured to add the forward sequence and the inverse pleat sequence to obtain a zero initial phase cosine function modulation sequence;

a sine function modulation sequence determining module 109, configured to subtract the forward sequence from the anti-aliasing sequence to obtain a zero initial phase sine function modulation sequence;

a first average amplitude determining module 110, configured to perform integral operation on an absolute value of the zero initial phase cosine function modulation sequence to obtain a first average amplitude of the zero initial phase cosine function modulation sequence;

a second average amplitude determining module 111, configured to perform integral operation on an absolute value of the zero initial phase sine function modulation sequence to obtain a second average amplitude of the zero initial phase sine function modulation sequence;

an average amplitude determining module 112, configured to determine whether the first average amplitude is greater than or equal to the second average amplitude, when the first average amplitude is greater than or equal to the second average amplitude, use the zero initial phase cosine function modulation sequence as a zero initial phase modulation sequence, and when the first average amplitude is smaller than the second average amplitude, use the zero initial phase sine function modulation sequence as a zero initial phase modulation sequence;

a truncated sequence obtaining module 113, configured to truncate the zero initial phase modulation sequence to obtain a truncated sequence;

a first vector sequence determining module 114, configured to multiply the cosine function of the reference frequency and the sine function of the reference frequency with the zero initial phase modulation sequence, respectively, to obtain a first real frequency vector sequence and a first imaginary frequency vector sequence;

a second vector sequence determining module 115, configured to multiply the cosine function of the reference frequency and the sine function of the reference frequency with the truncated sequence, respectively, to obtain a second real frequency vector sequence and a second imaginary frequency vector sequence;

a first notch sequence determining module 116, configured to perform digital notch on the first real frequency vector sequence and the first virtual frequency vector sequence, respectively, to obtain a first real frequency vector notch sequence and a first virtual frequency vector notch sequence;

a first integral value determining module 117, configured to perform integral operation on the first real frequency vector notch sequence and the first imaginary frequency vector notch sequence, respectively, to obtain a first real frequency vector integral value and a first imaginary frequency vector integral value;

a second notch sequence determining module 118, configured to perform digital notch on the second real frequency vector sequence and the second virtual frequency vector sequence, respectively, to obtain a second real frequency vector notch sequence and a second virtual frequency vector notch sequence;

a second integral value determining module 119, configured to perform integral operation on the second real frequency vector notch sequence and the second virtual frequency vector notch sequence, respectively, to obtain a second real frequency vector integral value and a second virtual frequency vector integral value;

a phase determining module 120, configured to convert the first imaginary frequency vector integrated value and the first real frequency vector integrated value into a first phase according to a preset phase conversion rule; converting the second imaginary frequency vector integral value and the second real frequency vector integral value into a second phase;

an initial phase determining module 121, configured to convert the first phase and the second phase into an initial phase of the zero initial phase modulation sequence according to a preset initial phase conversion rule;

and the full phase difference determining module 122 is configured to convert the initial phase of the zero initial phase modulation sequence into a full phase difference of the power signal according to a preset full phase difference conversion rule.

The power signal is a sinusoidal signal with a dominant fundamental component. The sine signal is broadly referred to as sine function signal and cosine function signal. The frequency range of the power signal is generally 45Hz to 55 Hz. So that the lower limit f of the frequency range of the power signal_minMay be taken to be 45 Hz. Presetting integer signal period number C_2πCan be set according to actual needs, for example, the integer signal period number C can be preset_2πSet to 11. In one embodiment, the preliminary sample sequence length determination module 101 may be based onDetermining a preliminary sample sequence length N_startWhere (int) denotes rounding, f_nIs a preset sampling frequency.

After the preliminary sampling sequence length determining module 101 obtains the preliminary sampling sequence length, the preliminary sampling sequence obtaining module 102 performs preliminary sampling on the power signal according to the preliminary sampling sequence length. For example, the power signal is a single fundamental frequency sinusoidal signal, the preliminary sampling sequence acquisition module 102 performs preliminary sampling on the single fundamental frequency sinusoidal signal according to the length of the preliminary sampling sequence, and an obtained preliminary sampling sequence X of the power signal_start(n) is:wherein A is a signal amplitude; omega is the signal frequency;is the sampling interval; f. of_nA preset sampling frequency is set; n-0, 1,2,3_start-1, being a sequence discrete number;is the initial phase of the signal; n is a radical of_startIs long for preliminary sampling sequenceAnd (4) degree.

After the preliminary sampling sequence obtaining module 102 obtains the preliminary sampling sequence, the reference frequency determining module 103 may perform frequency preliminary measurement on the preliminary sampling sequence by using a zero-crossing method, a filtering-based algorithm, a wavelet transform-based algorithm, a neural network-based algorithm, a DFT-based frequency algorithm, or a phase difference-based frequency algorithm, to obtain a preliminary frequency ω o. In one embodiment, the reference frequency determination module 103 may use the preliminary frequency as a reference frequency, i.e., the reference frequency ω_s＝ωo。

After the reference frequency is obtained by the reference frequency determination module 103, in one embodiment, the unit cycle sequence length determination module 104 may be based onDetermining a unit period sequence length N_2π. Wherein (int) is an integer, f_nIn order to preset the sampling frequency, the sampling frequency is set,f_sreference frequency, ω, in Hz_sIs the reference frequency in rad/s units. The sequence length integer quantization per unit period has an error within 1 sampling interval.

After the unit cycle sequence length determining module 104 obtains the unit cycle sequence length, in one embodiment, the preset sequence length determining module 105 determines the unit cycle sequence length according to N ═ int (C)₂πN₂Pi) determines the preset sequence length N. Wherein (int) is an integer, C_2πFor presetting the number of integer signal cycles, N_2πIs the unit period sequence length. From the equation, the predetermined sequence length N and the integer number of signal periods C_2πAnd (7) corresponding. The predetermined sequence length N may be a unit period sequence length N_2π11 times higher than the original value. The predetermined sequence length includes an integer number of signal periods that is approximate due to errors.

After the preset sequence length determining module 105 obtains the preset sequence length N, the forward sequence obtaining module 106 obtains the preset sequence according to the preset sequenceLength, obtaining a forward sequence from the preliminary sampling sequence. In one embodiment, the forward sequence acquisition module 106 acquires the forward sequence X based on the preliminary sampling sequence obtained by the preliminary sampling sequence acquisition module 102_i(n) is:wherein, X_start(n) is a preliminary sampling sequence; a is the signal amplitude; omega is the signal frequency; t is_nIs the sampling interval; n-0, 1,2, 3.. and N-1, which are sequence discrete numbers; n is less than or equal to N_start；Is the initial phase of the signal; n is the forward sequence length, i.e. the predetermined sequence length.

Based on the forward sequence obtained by the forward sequence obtaining module 106, the inverse pleat sequence X obtained by the inverse pleat sequence obtaining module 107_-i(-n) is: x_-i(-n)＝X_i(N-n)＝Acos(-ωT_nN + β), where N is 0,1,2,3,.. times, N-1, β is the unwrapped sequence initial phase, which is the cut-off phase of the forward sequence, i.e. the cut-off phase of the power signal, and N is the unwrapped sequence length, which is the same as the forward sequence length as shown in fig. 2.

Based on the forward sequence obtained by the forward sequence obtaining module 106, the inverse pleat sequence obtained by the inverse pleat sequence obtaining module 107, and the zero initial phase cosine function modulation sequence X obtained by the cosine function modulation sequence determining module 108_cos(n) is:

wherein,modulating the sequence amplitude for a cosine function;and modulating the initial phase of the sequence for the cosine function. The zero initial phase cosine function modulation sequence carriesAnd (4) information.

Based on the forward sequence obtained by the forward sequence obtaining module 106 and the inverse pleat sequence obtained by the inverse pleat sequence obtaining module 107, the zero initial phase sine function modulation sequence X obtained by the sine function modulation sequence determining module 109_sin(n) is:

wherein,modulating the amplitude of the sequence by a sine function with zero initial phase in a unit v;the initial phase of the sequence is modulated by a zero initial phase sine function, with the unit being rad.

In one embodiment, the first average magnitude determination module 110 may be based onObtaining the first average amplitude V_cos-avgWherein N is 0,1,2,3_cosAnd (n) is a zero initial phase cosine function modulation sequence.

In one embodiment, the second average magnitude determination module 111 may be based onObtaining the second average amplitude V_sin-vagWherein N is 0,1,2,3_sinAnd (n) is a zero initial phase sine function modulation sequence.

The first average amplitude determining module 110 obtains a first average amplitude V_cos-avgAnd a second average amplitude determination module 111 a second average amplitude V_sin-vagThen, the average amplitude determination module 112 compares the magnitudes of the two. When the first average amplitude V_cos-avgGreater than or equal to the second average amplitude value V_sin-vagThen, the average amplitude determination module 112 takes the zero initial phase cosine function modulation sequence as a zero initial phase modulation sequence; when the first average amplitude V_cos-avgLess than the second average amplitude V_sin-vagThe average amplitude determination module 112 takes the zero initial phase sine function modulation sequence as a zero initial phase modulation sequence.

After the average amplitude determining module 112 obtains the zero initial phase modulation sequence, the truncated sequence obtaining module 113 truncates the zero initial phase modulation sequence, as shown in the following formula, to obtain a truncated sequence:

X_s(n)＝X_out(n)

N_s＝N-M_s

M_s＝0.25N_2π

wherein, X_s(n) is a truncated sequence; n is the zero initial phase modulation sequence length of the dimensionless unit, i.e. the length of the predetermined sequenceDegree; n is a radical of_sTruncated sequence length in dimensionless units; m_sThe unit is dimensionless relative to the shortened value of the zero initial phase modulation sequence length; n is a radical of_2πThe length of the unit period sequence in dimensionless units.

As shown in fig. 5, in one embodiment, the phase determination module 120 may include:

a first ratio determining unit 1201, configured to determine a first ratio of the first imaginary frequency vector integral value and the first real frequency vector integral value when the zero initial phase modulation sequence is the zero initial phase cosine function modulation sequence;

a first phase determining unit 1202, configured to determine an inverse number of an arctangent function value of the first ratio as the first phase;

a second ratio determining unit 1203, configured to determine a second ratio of the second imaginary frequency vector integrated value and the second real frequency vector integrated value when the zero initial phase modulation sequence is the zero initial phase cosine function modulation sequence;

a second phase determining unit 1204, configured to use the inverse of the arctan function value of the second ratio as the second phase.

As shown in the following equation, when the zero initial phase modulation sequence is the zero initial phase cosine function modulation sequence, the first phase and the second phase obtained by the phase determining module 120 are respectively:

As shown in fig. 6, in another embodiment, the phase determination module 120 may further include:

a third ratio determining unit 1205, configured to determine a third ratio of the first real frequency vector integrated value and the first imaginary frequency vector integrated value when the zero initial phase modulation sequence is the zero initial phase sine function modulation sequence;

a first phase detecting unit 1206, configured to use an arctan function value of the third ratio as the first phase;

a fourth ratio determining unit 1207, configured to determine a fourth ratio of the second real frequency vector integrated value to the second imaginary frequency vector integrated value when the zero initial phase modulation sequence is the zero initial phase sine function modulation sequence;

a second phase detection unit 1208, configured to use the arctan function value of the fourth ratio as the second phase.

As shown in the following equation, when the zero initial phase modulation sequence is the zero initial phase sine function modulation sequence, the first phase and the second phase obtained by the phase determining module 120 are respectively:

after the phase determining module 120 obtains the first phase and the second phase, in one embodiment, the initial phase determining module 121 is based onDetermining an initial phase of the zero initial phase modulation sequenceWherein the pH is₁Is the first phase, PH₂Is a second phase, N is a predetermined sequence length, N_sIs a truncated sequence length.

The full phase difference determining module 122 may determine the full phase difference according to the initial phase of the zero initial phase modulation sequence and a preset integer signal period numberDetermining a full phase difference △ PH of the power signal, where C_2πThe number of signal cycles is a preset integer number of signal cycles,and modulating the initial phase of the sequence for the zero initial phase.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A method for detecting a full phase difference of an electric power signal, comprising the steps of:

converting the first imaginary frequency vector integral value and the first real frequency vector integral value into a first phase according to a preset phase conversion rule; converting the second imaginary frequency vector integral value and the second real frequency vector integral value into a second phase, wherein the expression of the preset phase conversion rule is as follows:orWherein PH is a phase, I is an imaginary frequency vector integral value, and R is a real frequency vector integral value;

converting the first phase and the second phase into an initial phase of the zero initial phase modulation sequence according to a preset initial phase conversion rule, wherein an expression of the preset initial phase conversion rule is as follows:wherein,indicating the initial phase, PH, of the zero initial phase modulation sequence₁Representing said first phase, PH₂Representing said second phase, N being a predetermined sequence length，N_SIs a truncated sequence length;

converting the initial phase of the zero initial phase modulation sequence into the full phase difference of the electric power signal according to a preset full phase difference conversion rule, wherein the preset full phase conversion rule has an expression:wherein △ PH represents the total phase difference, 2 pi C2 pi is the total phase difference of integral multiple of 2 pi,indicating the initial phase of the zero initial phase modulation sequence.

2. The method according to claim 1, wherein if the zero initial phase modulation sequence is the zero initial phase cosine function modulation sequence, the first imaginary frequency vector integral value and the first real frequency vector integral value are converted into a first phase according to a predetermined phase conversion rule; the step of converting the second imaginary frequency vector integral value and the second real frequency vector integral value into a second phase includes:

the second phase is the inverse of the arctan function of the second ratio.

3. The method according to claim 1, wherein if the zero initial phase modulation sequence is the zero initial phase sine function modulation sequence, the first imaginary frequency vector integrated value and the first real frequency vector integrated value are converted into a first phase according to a preset phase conversion rule; the step of converting the second imaginary frequency vector integral value and the second real frequency vector integral value into a second phase includes:

taking an arctangent function value of the third ratio as the first phase;

taking an arctan function value of the fourth ratio as the second phase.

4. A system for full phase difference detection of a power signal, comprising:

a phase determining module, configured to convert the first imaginary frequency vector integrated value and the first real frequency vector integrated value into a first phase according to a preset phase conversion rule; converting the second imaginary frequency vector integral value and the second real frequency vector integral value into a second phase, wherein the expression of the preset phase conversion rule is as follows:orWherein PH is a phase, I is an imaginary frequency vector integral value, and R is a real frequency vector integral value;

an initial phase determining module, configured to convert the first phase and the second phase into an initial phase of the zero initial phase modulation sequence according to a preset initial phase conversion rule, where an expression of the preset initial phase conversion rule is:wherein,indicating the initial phase, PH, of the zero initial phase modulation sequence₁Representing said first phase, PH₂Representing said second phase, N being a predetermined sequence length, N_SIs a truncated sequence length;

a full phase difference determining module, configured to convert the initial phase of the zero initial phase modulation sequence into a full phase difference of the power signal according to a preset full phase difference conversion rule, where the preset full phase conversion rule has an expression:wherein △ PH represents the total phase difference, 2 pi C2 pi is the total phase difference of integral multiple of 2 pi,indicating the initial phase of the zero initial phase modulation sequence.

5. The system of claim 4, wherein the phase determination module comprises:

a first ratio determining unit, configured to determine a first ratio of the first imaginary frequency vector integral value and the first real frequency vector integral value when the zero initial phase modulation sequence is the zero initial phase cosine function modulation sequence;

a first phase determining unit configured to determine an inverse number of an arctangent function value of the first ratio as the first phase;

a second ratio determining unit, configured to determine a second ratio between the second imaginary frequency vector integral value and the second real frequency vector integral value when the zero initial phase modulation sequence is the zero initial phase cosine function modulation sequence;

a second phase determining unit configured to set an inverse number of an arctangent function value of the second ratio as the second phase.

6. The system of claim 4, wherein the phase determination module comprises:

a third ratio determining unit, configured to determine a third ratio between the first real frequency vector integrated value and the first imaginary frequency vector integrated value when the zero initial phase modulation sequence is the zero initial phase sine function modulation sequence;

a first phase detection unit configured to use an arctangent function value of the third ratio as the first phase;

a fourth ratio determining unit, configured to determine a fourth ratio between the second real frequency vector integrated value and the second imaginary frequency vector integrated value when the zero initial phase modulation sequence is the zero initial phase sine function modulation sequence;

a second phase detection unit configured to use the arctan function value of the fourth ratio as the second phase.