CN103647287A - Dynamic voltage reactive compensation method - Google Patents

Abstract

The invention discloses a technical scheme of a dynamic voltage reactive compensation method in the field of an electrical network. The method provided by the technical scheme comprises the following steps: through a first coordinate transformation step, converting instantaneous electrical network voltages Usa, Usb and Usc of a three-phase power line and load instantaneous currents iLa, iLb and iLc into components U[alpha] and U[beta], and i[alpha] and i[beta] under an alpha-beta coordinate system; through a second coordinate transformation step, calculating an instantaneous active power p and an instantaneous reactive power q; through a filtering step, obtaining a DC component p-hat of the instantaneous active power p and a DC component q-hat of the instantaneous reactive power q; through a first coordinate inverse transformation step, obtaining fundamental waves I[alpha]f and I [beta]f of the components i[alpha] and i[beta] of the load instantaneous currents iLa, iLb and iLc under the alpha-beta coordinate system; through a second coordinate inverse transformation step, obtaining fundamental waves ILaf, iLbf and iLcf of the load instantaneous currents iLa, iLb and iLc; and finally calculating compensation currents i<*>ah, i<*>bh and i<*>ch of the three-phase power line. The technical advantages are as follows: the response speed of a dynamic voltage reactive power compensator can be improved, the harmonic waves on the three-phase power line can be effectively inhibited, and the THD values of the three-phase power line can be controlled to be within 2%.

Description

A kind of dynamic electric voltage reactive-load compensation method

Technical field

The present invention relates to a kind of dynamic electric voltage reactive-load compensation method in electrical network field.

Background technology

Detect accurately and fast harmonic current in electrical network, and to produce the required reactive power compensation electric current of load be the major function of dynamic electric voltage reactive power compensator.Current dynamic electric voltage reactive power compensator, what it mainly adopted is to adopt to obtain load instantaneous current i according to the dynamic electric voltage reactive-load compensation method of instantaneous reactive power _la, i _lb, i _lcfirst-harmonic i _laf, i _lbf, i _lcf.The method low-response, suppresses poor to the harmonic wave of electrical network.

Summary of the invention

The object of the invention is, in order to overcome the deficiencies in the prior art, provides a kind of dynamic electric voltage reactive-load compensation method, and it can improve the response speed of dynamic electric voltage reactive power compensator, and effectively suppresses the harmonic wave on three-phase power line.

A kind of technical scheme that realizes above-mentioned purpose is: a kind of dynamic electric voltage reactive-load compensation method, comprises the following steps:

The first coordinate transform step: the instantaneous line voltage u of three-phase power line _sa, u _sband u _sc, and load instantaneous current i _la, i _lb, i _lccarry out C32 coordinate transform, obtain the instantaneous line voltage u of three-phase power line _sa, u _sband u _sccomponent u under alpha-beta coordinate system _αand u _β, and load instantaneous current i _la, i _lb, i _lccomponent i under alpha-beta coordinate system _αand i _β, this step formula is:

$\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}}\\ u_{\mathrm{\&beta;}}\end{array}\right]=C_{32}\left[\begin{array}{c}{u}_{\mathrm{sa}}\\ u_{\mathrm{sb}}\\ u_{\mathrm{sc}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -1/2& -1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{sa}}\\ u_{\mathrm{sb}}\\ u_{\mathrm{sc}}\end{array}\right];$

$\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]=C_{32}\left[\begin{array}{c}{i}_{\mathrm{La}}\\ i_{\mathrm{Lb}}\\ i_{\mathrm{Lc}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -1/2& -1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{La}}\\ i_{\mathrm{Lb}}\\ i_{\mathrm{Lc}}\end{array}\right];$

The second coordinate transform step: by the instantaneous line voltage u of three-phase power line _sa, u _sband u _sccomponent u under alpha-beta coordinate system _αand u _β, and load instantaneous current i _la, i _lb, i _lccomponent i under alpha-beta coordinate system _αand i _β, calculating instantaneous active power p and instantaneous reactive power q, the computing formula of this step is:

$\left[\begin{array}{c}p\\ q\end{array}\right]=C_{\mathrm{pq}}\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]=\left[\begin{array}{cc}{u}_{\mathrm{\&alpha;}}& u_{\mathrm{\&beta;}}\\ u_{\mathrm{\&beta;}}& -u_{\mathrm{\&alpha;}}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right];$

Filter step: use three rank Chebyshev filters to carry out low-pass filtering to instantaneous active power p and instantaneous reactive power q, obtain the DC component of instantaneous active power p

dC component with instantaneous reactive power q

The first coordinate inversion step: the DC component of instantaneous active power p dC component with instantaneous reactive power q

carry out coordinate inversion, obtain load instantaneous current i _la, i _lb, i _lccomponent i under alpha-beta coordinate system _αand i _βfirst-harmonic, i _{α f}and i _{β f},

The computing formula of this step is;

$\left[\begin{array}{c}{i}_{\mathrm{\&alpha;f}}\\ i_{\mathrm{\&beta;f}}\end{array}\right]={\left[\begin{array}{cc}{u}_{\mathrm{\&alpha;}}& u_{\mathrm{\&beta;}}\\ u_{\mathrm{\&beta;}}& -u_{\mathrm{\&alpha;}}\end{array}\right]}^{-1}\left[\begin{array}{c}\stackrel{\&OverBar;}{p}\\ \stackrel{\&OverBar;}{q}\end{array}\right]=\frac{1}{u_{\mathrm{\&alpha;}}^2+u_{\mathrm{\&beta;}}^2}\left[\begin{array}{cc}{u}_{\mathrm{\&alpha;}}& u_{\mathrm{\&beta;}}\\ u_{\mathrm{\&beta;}}& -u_{\mathrm{\&alpha;}}\end{array}\right]\left[\begin{array}{c}\stackrel{\&OverBar;}{p}\\ \stackrel{\&OverBar;}{q}\end{array}\right]=\left[\begin{array}{c}\frac{u_{\mathrm{\&alpha;}}\stackrel{\&OverBar;}{p}+u_{\mathrm{\&beta;}}\stackrel{\&OverBar;}{q}}{u_{\mathrm{\&alpha;}}^2+u_{\mathrm{\&beta;}}^2}\\ \frac{u_{\mathrm{\&beta;}}\stackrel{\&OverBar;}{p}-u_{\mathrm{\&alpha;}}\stackrel{\&OverBar;}{q}}{u_{\mathrm{\&alpha;}}^2+u_{\mathrm{\&beta;}}^2}\end{array}\right];$

The second coordinate inversion step: by load instantaneous current i _la, i _lband i _lccomponent i under alpha-beta coordinate system _αand i _βfirst-harmonic, i _{α f}and i _{β f}, calculate load instantaneous current i _la, i _lband i _lcfirst-harmonic i _laf, i _lbfand i _lcf, the computing formula of this step is:

$\left[\begin{array}{c}{i}_{\mathrm{Laf}}\\ i_{\mathrm{Lbf}}\\ i_{\mathrm{Lcf}}\end{array}\right]=C_{23}\left[\begin{array}{c}{i}_{\mathrm{\&alpha;f}}\\ i_{\mathrm{\&beta;f}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}1& 0\\ -1/2& \sqrt{3}/2\\ -1/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;f}}\\ i_{\mathrm{\&beta;f}}\end{array}\right];$

；

Offset current calculation procedure: by calculating load instantaneous current i _la, i _lband i _lcfirst-harmonic i _laf, i _lbfand i _lcf, calculate the offset current on three-phase power line with

Adopted the technical scheme of a kind of dynamic electric voltage reactive-load compensation method of the present invention, by the instantaneous line voltage u of the first coordinate transform step three-phase power line _sa, u _sband u _sc, and load instantaneous current i _la, i _lband i _lcchange its component u under alpha-beta coordinate system into _αand u _β, and i _αand i _β, by the second coordinate transform step, calculate instantaneous active power p and instantaneous reactive power q, then by filter step, obtain the DC component of instantaneous active power p dC component with instantaneous reactive power q

then by load instantaneous current i _la, i _lb, i _lccomponent i under alpha-beta coordinate system _αand i _βfirst-harmonic, i _{α f}and i _{β f}, by the second coordinate inversion step, obtaining load instantaneous current i _la, i _lband i _lcfirst-harmonic i _laf, i _lbfand i _lcf, finally calculate the offset current on three-phase power line

with

technical scheme: its technique effect is: can improve the response speed of dynamic electric voltage reactive power compensator, and effectively suppress the harmonic wave on three-phase power line, the THD value on three-phase power line is controlled in 2%.

Accompanying drawing explanation

Fig. 1 is the structural topology schematic diagram of a kind of dynamic electric voltage reactive-load compensation method of the present invention.

Embodiment

Refer to Fig. 1, the present inventor is in order to understand technical scheme of the present invention better, below by embodiment particularly, and is described in detail by reference to the accompanying drawings:

The first coordinate transform step: the instantaneous line voltage u of three-phase power line _sa, u _sband u _sc, and load instantaneous current i _la, i _lb, i _lccarry out C32 coordinate transform, obtain the instantaneous line voltage u of three-phase power line _sa, u _sband u _sccomponent u under alpha-beta coordinate system _αand u _β, and load instantaneous current i _la, i _lb, i _lccomponent i under alpha-beta coordinate system _αand i _β.This step formula is:

$\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}}\\ u_{\mathrm{\&beta;}}\end{array}\right]=C_{32}\left[\begin{array}{c}{u}_{\mathrm{sa}}\\ u_{\mathrm{sb}}\\ u_{\mathrm{sc}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -1/2& -1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{sa}}\\ u_{\mathrm{sb}}\\ u_{\mathrm{sc}}\end{array}\right];$

$\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]=C_{32}\left[\begin{array}{c}{i}_{\mathrm{La}}\\ i_{\mathrm{Lb}}\\ i_{\mathrm{Lc}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -1/2& -1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{La}}\\ i_{\mathrm{Lb}}\\ i_{\mathrm{Lc}}\end{array}\right].$

The second coordinate transform step: the instantaneous line voltage u of three-phase power line _sa, u _sband u _sccomponent u under alpha-beta coordinate system _αand u _β, and load instantaneous current i _la, i _lb, i _lccomponent i under alpha-beta coordinate system _αand i _β, calculate instantaneous active power p and instantaneous reactive power q.The computing formula of this step is:

$\left[\begin{array}{c}p\\ q\end{array}\right]=C_{\mathrm{pq}}\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]=\left[\begin{array}{cc}{u}_{\mathrm{\&alpha;}}& u_{\mathrm{\&beta;}}\\ u_{\mathrm{\&beta;}}& -u_{\mathrm{\&alpha;}}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right].$

Filter step: use three rank Chebyshev filters to carry out low-pass filtering to instantaneous active power p and instantaneous reactive power q, obtain the DC component of instantaneous active power p dC component with instantaneous reactive power q

the cut-off frequency of three rank Chebyshev filters is 50Hz, the decay≤1dB in passband, resistance band attenuation≤-35dB.

The first coordinate inversion step: the DC component of instantaneous active power p

dC component with instantaneous reactive power q carry out coordinate inversion, obtain load instantaneous current i _la, i _lb, i _lccomponent i under alpha-beta coordinate system _αand i _βfirst-harmonic, i _{α f}and i _{β f}.

The computing formula of this step is;

$\left[\begin{array}{c}{i}_{\mathrm{\&alpha;f}}\\ i_{\mathrm{\&beta;f}}\end{array}\right]={\left[\begin{array}{cc}{u}_{\mathrm{\&alpha;}}& u_{\mathrm{\&beta;}}\\ u_{\mathrm{\&beta;}}& -u_{\mathrm{\&alpha;}}\end{array}\right]}^{-1}\left[\begin{array}{c}\stackrel{\&OverBar;}{p}\\ \stackrel{\&OverBar;}{q}\end{array}\right]=\frac{1}{u_{\mathrm{\&alpha;}}^2+u_{\mathrm{\&beta;}}^2}\left[\begin{array}{cc}{u}_{\mathrm{\&alpha;}}& u_{\mathrm{\&beta;}}\\ u_{\mathrm{\&beta;}}& -u_{\mathrm{\&alpha;}}\end{array}\right]\left[\begin{array}{c}\stackrel{\&OverBar;}{p}\\ \stackrel{\&OverBar;}{q}\end{array}\right]=\left[\begin{array}{c}\frac{u_{\mathrm{\&alpha;}}\stackrel{\&OverBar;}{p}+u_{\mathrm{\&beta;}}\stackrel{\&OverBar;}{q}}{u_{\mathrm{\&alpha;}}^2+u_{\mathrm{\&beta;}}^2}\\ \frac{u_{\mathrm{\&beta;}}\stackrel{\&OverBar;}{p}-u_{\mathrm{\&alpha;}}\stackrel{\&OverBar;}{q}}{u_{\mathrm{\&alpha;}}^2+u_{\mathrm{\&beta;}}^2}\end{array}\right].$

The second coordinate inversion step: load instantaneous current i _la, i _lb, i _lccomponent i under alpha-beta coordinate system _αand i _βfirst-harmonic, i _{α f}and i _{β f}, calculate load instantaneous current i _la, i _lb, i _lcfirst-harmonic i _laf, i _lbf, i _lcf.The computing formula of this step is:

$\left[\begin{array}{c}{i}_{\mathrm{Laf}}\\ i_{\mathrm{Lbf}}\\ i_{\mathrm{Lcf}}\end{array}\right]=C_{23}\left[\begin{array}{c}{i}_{\mathrm{\&alpha;f}}\\ i_{\mathrm{\&beta;f}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}1& 0\\ -1/2& \sqrt{3}/2\\ -1/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;f}}\\ i_{\mathrm{\&beta;f}}\end{array}\right].$

Offset current calculation procedure: by calculating load instantaneous current i _la, i _lband i _lcfirst-harmonic i _laf, i _lbfand i _lcf, calculate the offset current on three-phase power line

with

Nonlinear load adopts three phase rectifier module bridge joint 30 Ω resistance; Compensator transformer no-load voltage ratio is set as 1:1; Side compensation reactor in parallel is made as 3mH, and filter capacitor is 10uF; Series side filter inductance 3mH, filter capacitor 5uF; Line voltage 220V, frequency is 50Hz, when 0.04s, supply voltage occurs to fall with the voltage of phase hit, saltus step angle is 30 °, amplitude drops under the model of 140V, THD(total harmonic distortion) value dropped to 1.85% by 28.58%.

Claims (1)

1. a dynamic electric voltage reactive-load compensation method, comprises the following steps:

The first coordinate transform step: the instantaneous line voltage u of three-phase power line _sa, u _sband u _sc, and load instantaneous current i _la, i _lb, i _lccarry out C32 coordinate transform, obtain the instantaneous line voltage u of three-phase power line _sa, u _sband u _sccomponent u under alpha-beta coordinate system _αand u _β, and load instantaneous current i _la, i _lb, i _lccomponent i under alpha-beta coordinate system _αand i _β, this step formula is:

$\left[\begin{array}{c}{u}_{\mathrm{\&alpha;}}\\ u_{\mathrm{\&beta;}}\end{array}\right]=C_{32}\left[\begin{array}{c}{u}_{\mathrm{sa}}\\ u_{\mathrm{sb}}\\ u_{\mathrm{sc}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -1/2& -1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{sa}}\\ u_{\mathrm{sb}}\\ u_{\mathrm{sc}}\end{array}\right];$

$\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]=C_{32}\left[\begin{array}{c}{i}_{\mathrm{La}}\\ i_{\mathrm{Lb}}\\ i_{\mathrm{Lc}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -1/2& -1/2\\ 0& \sqrt{3}/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{La}}\\ i_{\mathrm{Lb}}\\ i_{\mathrm{Lc}}\end{array}\right];$

The second coordinate transform step: by the instantaneous line voltage u of three-phase power line _sa, u _sband u _sccomponent u under alpha-beta coordinate system _αand u _β, and load instantaneous current i _la, i _lb, i _lccomponent i under alpha-beta coordinate system _αand i _β, calculating instantaneous active power p and instantaneous reactive power q, the computing formula of this step is:

$\left[\begin{array}{c}p\\ q\end{array}\right]=C_{\mathrm{pq}}\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right]=\left[\begin{array}{cc}{u}_{\mathrm{\&alpha;}}& u_{\mathrm{\&beta;}}\\ u_{\mathrm{\&beta;}}& -u_{\mathrm{\&alpha;}}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;}}\\ i_{\mathrm{\&beta;}}\end{array}\right];$

Filter step: use three rank Chebyshev filters to carry out low-pass filtering to instantaneous active power p and instantaneous reactive power q, obtain the DC component of instantaneous active power p

dC component with instantaneous reactive power q

The first coordinate inversion step: the DC component of instantaneous active power p

dC component with instantaneous reactive power q

carry out coordinate inversion, obtain load instantaneous current i _la, i _lb, i _lccomponent i under alpha-beta coordinate system _αand i _βfirst-harmonic, i _{α f}and i _{β f},

The computing formula of this step is;

$\left[\begin{array}{c}{i}_{\mathrm{\&alpha;f}}\\ i_{\mathrm{\&beta;f}}\end{array}\right]={\left[\begin{array}{cc}{u}_{\mathrm{\&alpha;}}& u_{\mathrm{\&beta;}}\\ u_{\mathrm{\&beta;}}& -u_{\mathrm{\&alpha;}}\end{array}\right]}^{-1}\left[\begin{array}{c}\stackrel{\&OverBar;}{p}\\ \stackrel{\&OverBar;}{q}\end{array}\right]=\frac{1}{u_{\mathrm{\&alpha;}}^2+u_{\mathrm{\&beta;}}^2}\left[\begin{array}{cc}{u}_{\mathrm{\&alpha;}}& u_{\mathrm{\&beta;}}\\ u_{\mathrm{\&beta;}}& -u_{\mathrm{\&alpha;}}\end{array}\right]\left[\begin{array}{c}\stackrel{\&OverBar;}{p}\\ \stackrel{\&OverBar;}{q}\end{array}\right]=\left[\begin{array}{c}\frac{u_{\mathrm{\&alpha;}}\stackrel{\&OverBar;}{p}+u_{\mathrm{\&beta;}}\stackrel{\&OverBar;}{q}}{u_{\mathrm{\&alpha;}}^2+u_{\mathrm{\&beta;}}^2}\\ \frac{u_{\mathrm{\&beta;}}\stackrel{\&OverBar;}{p}-u_{\mathrm{\&alpha;}}\stackrel{\&OverBar;}{q}}{u_{\mathrm{\&alpha;}}^2+u_{\mathrm{\&beta;}}^2}\end{array}\right];$

The second coordinate inversion step: by load instantaneous current i _la, i _lband i _lccomponent i under alpha-beta coordinate system _αand i _βfirst-harmonic, i _{α f}and i _{β f}, calculate load instantaneous current i _la, i _lband i _lcfirst-harmonic i _laf, i _lbfand i _lcf, the computing formula of this step is:

$\left[\begin{array}{c}{i}_{\mathrm{Laf}}\\ i_{\mathrm{Lbf}}\\ i_{\mathrm{Lcf}}\end{array}\right]=C_{23}\left[\begin{array}{c}{i}_{\mathrm{\&alpha;f}}\\ i_{\mathrm{\&beta;f}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}1& 0\\ -1/2& \sqrt{3}/2\\ -1/2& -\sqrt{3}/2\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\&alpha;f}}\\ i_{\mathrm{\&beta;f}}\end{array}\right];$

Offset current calculation procedure: by calculating load instantaneous current i _la, i _lband i _lcfirst-harmonic i _laf, i _lbfand i _lcf, calculate the offset current on three-phase power line

with