CN103269211B - The digital filtering method of three-phase alternating current system measurement data - Google Patents

Abstract

The digital filtering method of a kind of three-phase alternating current system measurement data, including step: by three-phase voltage signal V_A、V_B、V_CBe converted to the voltage signal V under biphase α β coordinate system_α、V_β；According to the transmission function set respectively to voltage signal V_α、V_βCarry out low-pass filtering and obtain voltage signal V'_α、V'_β；Calculate described voltage signal V'_α、V'_βBase Ld phase δ；The base Ld phase delay angle δ of low-pass filtering is calculated according to transferometer₀；According to base Ld phase δ by voltage signal V'_α、V'_βBe converted to rotate the DC voltage V under dq two phase coordinate system_d、V_q；With δ δ₀For angle of transformation by DC voltage V_d、V_qBe converted to the voltage signal V' under three phase coordinates_A、V'_B、V'_C.The digital filtering method of above-mentioned three-phase alternating current system measurement data, can efficiently solve the base Ld phase delay issue of tradition filtering mode, improves the phase controlling precision of power system.

Description

The digital filtering method of three-phase alternating current system measurement data

Technical field

The present invention relates to digital filtering technique field, particularly relate to the numeral filter of a kind of three-phase alternating current system measurement data Wave method.

Background technology

Along with high-power switch device is in the application in the fields such as wind-power electricity generation, photovoltaic generation, Survey of Flexible AC Transmission System, power train System presents more and more significant non-linear, especially applies voltage source converter (VSC) based on pulsewidth modulation (PWM) technology Occasion, high order characteristic harmonics amplitude is close, possibly even beyond fundamental frequency amplitude, in order to solve the problems referred to above, can take be System primary side installs the scheme of wave filter additional, but due to the popularity of higher hamonic wave frequency spectrum, uncertainty, and filter apparatus cost Higher, the obtained effect of this technology is the most undesirable.

The wave distortion caused due to higher hamonic wave makes system normally to control and accurately measures, therefore, and existing electricity Force system typically can carry out the digital filtering of single order or high-order lowpass in the measurement links of secondary system side to sampled data, currently Main research is all the parameter designing being transfer function H (s).But, actual central any physically realizable system all can be deposited Postponing, no matter how the coefficient in transfer function H (s) designs, three-phase alternating current system measurement data after filtering after, be all difficult to Avoiding filtering forward and backward base Ld phase and postpone situation, three-phase alternating current system measurement data percent harmonic distortion (THD) is the highest, There is severe deviations in the phase controlling making power system.

Summary of the invention

Based on this, it is necessary to for the problems referred to above, it is provided that the digital filtering method of a kind of three-phase alternating current system measurement data.

The digital filtering method of a kind of three-phase alternating current system measurement data, comprises the steps:

By three-phase voltage signal V_A、V_B、V_CBe converted to the voltage signal V under biphase α β coordinate system_α、V_β；

According to the transmission function set respectively to described voltage signal V_α、V_βCarry out low-pass filtering and obtain voltage signal V'_α、 V'_β；

Calculate described voltage signal V'_α、V'_βBase Ld phase δ；

The base Ld phase delay angle δ of described low-pass filtering is calculated according to described transferometer₀；

According to described base Ld phase δ by described voltage signal V'_α、V'_βBe converted to rotate the unidirectional current under dq two phase coordinate system Pressure V_d、V_q；

With δ-δ₀For angle of transformation by described DC voltage V_d、V_qBe converted to the voltage signal V' under three phase coordinates_A、V'_B、V'_C。

The digital filtering method of above-mentioned three-phase alternating current system measurement data, first sits three-phase voltage signal from ABC three-phase Mark is transformed to α β two phase coordinates, then carries out low-pass filtering under α β coordinate system, and filtered fundamental frequency value is transformed to by α β coordinate DC quantity under dq rotating coordinate system, and base Ld phase produced by low-pass filtering postpones δ₀Sit being returned ABC by dq coordinate transform Timestamp compensates, thus efficiently solves the base Ld phase delay issue of tradition filtering mode, improves the phase place of power system Control accuracy.

Accompanying drawing explanation

Fig. 1 is the digital filtering method flow chart of the three-phase alternating current system measurement data of an embodiment；

Fig. 2 is simulation example laboratory model construction schematic diagram；

Fig. 3 is the simulation experiment result schematic diagram.

Detailed description of the invention

Specific embodiment party to the digital filtering method of the three-phase alternating current system measurement data of the present invention below in conjunction with the accompanying drawings Formula is described in detail.

Fig. 1 shows the digital filtering method flow chart of the three-phase alternating current system measurement data of an embodiment, including such as Lower step:

Step S101: by three-phase voltage signal V_A、V_B、V_CBe converted to the voltage signal V under biphase α β coordinate system_α、V_β。

In one embodiment, also include before step S101: the measurement data of three-phase alternating current system is carried out sampling and obtains Obtain the voltage signal V under three phase coordinates_A、V_B、V_C。

Specifically, the voltage data V that sampling obtains will be measured in step S101_A、V_B、V_C, from static ABC tri-phase coordinates Being transformed to static α β two phase coordinates, the formula of conversion is as follows:

Wherein, ABC → α β coordinate is transformed to orthogonal transformation, arranges α phase and A same axis.

Step S102: according to the transmission function set respectively to described voltage signal V_α、V_βCarry out low-pass filtering and obtain voltage Signal V'_α、V'_β。

Specifically, calculating process includes below equation:

In formula, H (s) is the transmission function set,

Step S103: calculate described voltage signal V'_α、V'_βBase Ld phase δ.

Specifically, calculating process includes below equation:

δ=arctg(V'_β/V'_α)；

In formula, δ is base Ld phase, V'_α、V'_βIt is respectively the voltage signal of α β coordinate after filtering.

Step S104: calculate the base Ld phase delay angle δ of described low-pass filtering according to described transferometer₀。

Specifically, phase delay angle δ that angle is low-pass filtering link of transfer function H (j ω)₀, i.e. through low pass filtered After ripple, under biphase α β coordinate system, the base Ld phase δ of voltage signal postpones relative to the voltage signal of A, B, C three-phase under three phase coordinates δ₀, δ₀Calculating process includes below equation:

${\mathrm{\δ}}_0=\mathrm{arctg}\left(\frac{\mathrm{ImH}\left(\mathrm{j\ω}\right)}{\mathrm{ReH}\left(\mathrm{j\ω}\right)}\right);$

The transmission function of described low-pass filtering is H (j ω), and its formula can be expressed as:

$H\left(\mathrm{j\ω}\right)=\frac{a_0+a_1\mathrm{j\ω}}{b_0+b_1\mathrm{j\ω}-b_2{\mathrm{\ω}}^2};$

Wherein, a₀、a₁、b₀、b₁、b₂For default constant, equal to 1, ω is fundamental frequency angular frequency to the modulus value of H (j ω) | H (j ω) | Rate.

Step S105: according to described base Ld phase δ by described voltage signal V'_α、V'_βBe converted to rotate dq two phase coordinate system Under DC voltage V_d、V_q。

Specifically, calculating process includes below equation:

V_d+jV_q=(V_α+jV_β)e^-jδ；

In formula, V'_α、V'_βBeing respectively the voltage signal of α β coordinate after filtering, δ is base Ld phase, V_d、V_qIt is respectively dq to rotate The voltage signal of coordinate system.

Step S106: with δ-δ₀For angle of transformation by described DC voltage V_d、V_qBe converted to the alternating voltage letter under three phase coordinates Number V'_A、V'_B、V'_C。

Specifically, variable is returned static ABC tri-phase coordinates from rotating the biphase coordinate transform of dq, q axle advanced d axle is set, become Changing angle is δ-δ₀, its calculating process includes the following:

In formula, θ=δ-δ₀, by above-mentioned processing procedure, during low-pass filtering, produced base Ld phase postpones δ₀At dq → ABC coordinate transform link is compensated.

The digital filtering method of the three-phase alternating current system measurement data of the present invention, for the measurement data of three-phase alternating current system Process, first the three-phase voltage signal (containing higher hamonic wave) of sampling is transformed to α β two phase coordinates from ABC three-phase coordinate, then Carrying out low-pass filtering under α β coordinate system, filtered fundamental frequency value is transformed to the DC quantity under dq rotating coordinate system by α β coordinate, And base Ld phase produced by low-pass filtering postpones δ₀Compensate when being returned ABC coordinate by dq coordinate transform, thus efficient solution The certainly base Ld phase delay issue of tradition filtering mode.

In order to become apparent from technical scheme, illustrate a simulation example below in conjunction with the accompanying drawings.

Shown in Figure 2, Fig. 2 is simulation example laboratory model construction schematic diagram, and wherein the transmission function of low-pass filtering is adopted With simplest first-order filtering H (j ω)=G/ (1+Ts), parameter G=1.606, T=0.004 second.

The ABC three-phase voltage signal then inputted is V_A、V_B、V_C, fundamental frequency (50Hz) phase voltage virtual value is 1.0,7 subharmonic Content be 10%, 19 subharmonic content be 180%, total harmonic distortion factor (THD) is 180.278%, after filtering output voltage signal For V'_A、V'_B、V'_C。

As it is shown on figure 3, Fig. 3 is the simulation experiment result schematic diagram, V in figure_AFor input A phase voltage signal waveform, wherein, V'_AFor the A phase voltage signal waveform of output, V' after the filtering method of the present invention is filtered_AFundamental frequency virtual value be 1.0, And phase place and V_AIdentical, 7 subharmonic content be 1.812%, 19 subharmonic content be 12.007%, overall percent harmonic distortion (THD) It is 12.143%.

Even if by the experimental result of above-mentioned simulation example it can be seen that transfer function H (s) uses the most optimized and the simplest Single first-order low-pass wave function, the filtering method of the present invention also can make total harmonic distortion factor (THD) reduce by more than 90%, and base The amplitude of frequency and phase place keep constant.

Embodiment described above only have expressed the several embodiments of the present invention, and it describes more concrete and detailed, but also Therefore the restriction to the scope of the claims of the present invention can not be interpreted as.It should be pointed out that, for those of ordinary skill in the art For, without departing from the inventive concept of the premise, it is also possible to make some deformation and improvement, these broadly fall into the guarantor of the present invention Protect scope.Therefore, the protection domain of patent of the present invention should be as the criterion with claims.

Claims (5)

1. the digital filtering method of a three-phase alternating current system measurement data, it is characterised in that comprise the steps:

By three-phase voltage signal V_A、V_B、V_CBe converted to the voltage signal V under biphase α β coordinate system_α、V_β；

According to the transmission function set respectively to described voltage signal V_α、V_βCarry out low-pass filtering and obtain voltage signal V'_α、V'_β；

Calculate described voltage signal V'_α、V'_βBase Ld phase δ；

The base Ld phase delay angle δ of described low-pass filtering is calculated according to described transferometer₀；Including:

${\mathrm{\δ}}_0=arctg\left(\frac{\mathrm{Im}H\left(j\mathrm{\ω}\right)}{\mathrm{Re}H\left(j\mathrm{\ω}\right)}\right);$

Wherein, H (j ω) is transmission function, and its formula can be expressed as:

$H\left(j\mathrm{\ω}\right)=\frac{a_0+a_{1}j\mathrm{\ω}}{b_0+b_{1}j\mathrm{\ω}-b_2{\mathrm{\ω}}^2};$

Wherein, a₀、a₁、b₀、b₁、b₂For default constant, equal to 1, ω is fundamental frequency angular frequency to the modulus value of H (j ω) | H (j ω) |, j Imaginary part for plural number；

According to described base Ld phase δ by described voltage signal V'_α、V'_βBe converted to rotate the DC voltage under dq two phase coordinate system V_d、V_q；

With δ-δ₀For angle of transformation by described DC voltage V_d、V_qBe converted to the voltage signal V' under three phase coordinates_A、V'_B、V'_C。

The digital filtering method of three-phase alternating current system measurement data the most according to claim 1, it is characterised in that described By three-phase voltage signal V_A、V_B、V_CBe converted to the voltage signal V under biphase α β coordinate system_α、V_βStep also include:

The measurement data of three-phase alternating current system is carried out the voltage signal V under sampling acquisition three phase coordinates_A、V_B、V_C。

The digital filtering method of three-phase alternating current system measurement data the most according to claim 1, it is characterised in that described meter Calculate described voltage signal V'_α、V'_βThe step of base Ld phase δ include:

δ=arctg (V'_β/V'_α)；

In formula, δ is base Ld phase, V'_α、V'_βIt is respectively the voltage signal under α β coordinate after filtering.

The digital filtering method of three-phase alternating current system measurement data the most according to claim 1, it is characterised in that described According to described base Ld phase δ by described voltage signal V'_α、V'_βBe converted to rotate the DC voltage V under dq two phase coordinate system_d、V_q's Step includes:

V_d+jV_q=(V_α+jV_β)e^-jδ；

In formula, V'_α、V'_βBeing respectively the voltage signal under α β coordinate after filtering, δ is base Ld phase, V_d、V_qIt is respectively the biphase seat of dq Voltage signal under Biao, j is the imaginary part of plural number.

The digital filtering method of three-phase alternating current system measurement data the most according to claim 1, it is characterised in that with δ-δ₀ For angle of transformation by described DC voltage V_d、V_qBe converted to the voltage signal V' under three phase coordinates_A、V'_B、V'_CStep include:

Wherein, θ=δ-δ₀。