CN103036236A - Control method of wide frequency range multi-type harmonic comprehensive governance system - Google Patents

Abstract

The invention discloses a control method of a wide frequency range multi-type harmonic comprehensive governance system. The control method of the wide frequency range multi-type harmonic comprehensive governance system comprises the wide frequency range multi-type harmonic comprehensive governance system. The wide frequency range multi-type harmonic comprehensive governance system comprises a series active power filter and a parallel passive power filter. The series active power filter comprises an inverter, a filter circuit, and a series transformer. The inverter is connected with a secondary side of the series transformer through the filter circuit. A primary side of the transformer is in series connection with grid lines. The parallel passive power filter is in parallel connection with a load side of the series active power filter. The control method of the wide frequency range multi-type harmonic comprehensive governance system is based on a control method of a fundamental wave magnetic flux compensation principle of the transformer. A fundamental wave compensating current is injected at the secondary side of the transformer. The size of the fundamental wave compensating current is k times larger or smaller than a power system current, and the direction of the fundamental wave compensating current is opposite to that of the power system current. Impedance of the series transformer to a fundamental wave is zero. Normal operation of the power system cannot be influenced. High impedance to the harmonic wave is presented. Filtering effect of a passive power filter can be improved. A harmonic voltage is compensated. Simultaneously, resonance of power harmonic in series or parallel connection can be well restrained.

Description

The control method of wide frequency domain polymorphic type harmonic synthesis governing system

Technical field

The present invention relates to Active Power Filter-APF, particularly a kind of control method of wide frequency domain polymorphic type harmonic synthesis governing system.

Background technology

Along with being on the increase that power electronic equipment is used, the harmonic source kind increases, and the mains by harmonics environment becomes increasingly complex.The electrical network rectifying device is a kind of typical harmonic source, according to the difference of its DC side filter element, can roughly be divided into two kinds of current mode harmonic source and voltage-type harmonic sources.DC side adopts the rectifying device of inductor filter can regard the current mode harmonic source as, and DC side is that the rectifying device of capacitor filtering can be regarded the voltage-type harmonic source as.Because it is more extensive that early stage current mode rectifying device is used, more to the Research on Treatment of current mode harmonic source both at home and abroad, relatively less to the research of the resolution of voltage-type harmonic source.In recent years, along with the power electronic equipments such as frequency converter, Switching Power Supply, uninterrupted power supply and electric ballast use increasing, the voltage-type harmonic source is on the increase in the electrical network, becomes another kind of main harmonic source.And may not only contain the current mode harmonic source but also the voltage-type harmonic source be arranged in some occasion loads, harmonic problem be serious, need to carry out the comprehensive regulation to dissimilar harmonic sources.

At present, the improvement method of current mode, voltage-type harmonic source has been carried out a lot of researchs both at home and abroad, and to the research of dissimilar harmonic source comprehensive processing methods seldom.Some research conclusions show that parallel connection type active electric filter is fit to offset current type harmonic source, series connection type active electric power filter is fit to bucking voltage type harmonic source, but adopt parallel connection type active electric filter bucking voltage type harmonic source, when adopting series connection type active electric power filter offset current type harmonic source, the capital causes that harmonic wave amplifies phenomenon, and compensation effect is all bad.Traditional Hybrid Type Series Active Power Filter can offset current type harmonic source, but general employing of passive part organized single series resonance passive power filters more, when load-side contains harmonic voltage, the harmonic current that causes easily flowing through passive power filter is excessive, therefore is not suitable for the occasion that load-side has the harmonic voltage distortion.The hybrid passive filter that is formed by series connection passive filter and Parallel passive filter, can realize the comprehensive compensation to voltage-type and current mode harmonic wave, but the filter off-tune that the variation of series resonance passive filter parameters and mains frequency deviation cause adds the impact of filter internal resistance, may produce larger fundamental voltage landing, affect electrical network and normally move.The tradition series connection type active electric power filter adopts and detects load voltage, detects the control methods such as source current, compound detection owing to directly the harmonic signal of different frequency is unified control, produce easily the error of amplitude and phase place during stable state, and this error is difficult for adjusting and proofreading and correct, and the stable state control accuracy is not high enough.

Summary of the invention

Technical problem to be solved by this invention is, not enough for prior art, a kind of control method of wide frequency domain polymorphic type harmonic synthesis governing system is provided, realization is to the comprehensive regulation of current mode and voltage-type harmonic source, establishment mains by harmonics series and parallel resonance, the boostfiltering effect improves steady state controling precision.

For solving the problems of the technologies described above, the technical solution adopted in the present invention is: a kind of control method of wide frequency domain polymorphic type harmonic synthesis governing system, comprise wide frequency domain polymorphic type harmonic synthesis governing system, described wide frequency domain polymorphic type harmonic synthesis governing system comprises series connection type active electric power filter, passive power filter in parallel, described series connection type active electric power filter comprises inverter, filter circuit and transformer, described inverter is connected to the secondary of transformer through filter circuit, the former limit of described transformer is connected in the power network line, the described series connection type active electric power filter load-side of described passive power filter in parallel access in parallel, the method is:

1) detection of grid three-phase current i _Sa, i _Sb, i _Sc, the electrical network three-phase current be multiply by transformer primary secondary no-load voltage ratio and anti-phase, namely multiply by-k, make to comprise secondary compensating fundamental wave current signal in the electric current that obtains;

2) current signal that step 1) is obtained deducts inverter output current i _Ca, i _Cb, i _Cc, obtain the compensating fundamental wave current error signal;

3) the compensating fundamental wave current error signal is carried out the ip-iq direct transform, and through low pass filter, extract the real component of error signal

And idle component

4) the amplitude I of calculating compensating fundamental wave current error signal ₁And phase angle

Amplitude is carried out PI regulate, phase angle is carried out compensation of delay, obtain the reference quantity of amplitude and phase angle With

5) calculate current-modulation with reference to real component according to the reference quantity of amplitude and phase angle

And idle component

6) carry out the ip-iq inverse transformation, obtain three-phase current modulator control signal i ^*, control voltage source inverter output compensating fundamental wave electric current.

Described Parallel passive filter is the first-harmonic parallel resonance non active band exclusion filter that is made of inductance and electric capacity.

Compared with prior art, the beneficial effect that the present invention has is: Parallel passive filter of the present invention adopts first-harmonic parallel resonance passive filter, very little to the high order harmonic component impedance, the low order characteristic harmonics had less impedance, when load-side has the harmonic voltage distortion, can effectively limit the low-order harmonic size of current that flows through PPF, not affect the harmonic current inhibition simultaneously.And make wide frequency domain polymorphic type harmonic synthesis governing system can be applied to the occasion that load-side has the harmonic voltage distortion, realized the comprehensive compensation to current mode and voltage-type harmonic source; Employing is based on the control method of transformer first-harmonic flux compensation principle, inject a size at the transformer secondary and be the compensating fundamental wave electric current of power network current k times of opposite direction, making series transformer is zero to impedance of fundamental frequency, not affecting electrical network normally moves, simultaneously harmonic wave is presented very high impedance, can improve the filter effect of passive power filter, compensation harmonic voltage well suppresses mains by harmonics series and parallel resonance simultaneously; Serial active filter compensating fundamental wave electric current adopts astatic PI control method, only the amplitude of command signal is carried out proportional plus integral control, and do not affect its phase place, have dynamic property advantage good, that fix, be simple and easy to realize without steady-state error, switching frequency.

Description of drawings

Fig. 1 is the topology diagram of one embodiment of the invention wide frequency domain polymorphic type harmonic synthesis governing system;

Fig. 2 is the detection control block diagram of one embodiment of the invention wide frequency domain polymorphic type harmonic synthesis governing system.

Embodiment

As shown in Figure 1, one embodiment of the invention wide frequency domain polymorphic type harmonic synthesis governing system comprises series connection type active electric power filter and Parallel Resonant passive filter, the Parallel Resonant passive filter is the first-harmonic parallel resonance non active band exclusion filter that is made of inductance and electric capacity, series connection type active electric power filter by each cross streams output of three-phase voltage-type inverter through a LC output filter circuit after, be connected to an end of series transformer secondary, wherein the electric capacity of LC output filter circuit is in parallel with the transformer secondary, series transformer on the electrical network three-phase adopts the Y type to connect, the series transformer secondary other end is as the three-phase neutral point, the former limit of series transformer then is connected between electrical network and the harmonic source, the described series connection type active electric power filter load-side of Parallel Resonant passive power filter access in parallel.Series active power filter adopts the control method based on transformer first-harmonic flux compensation principle among the present invention, is k such as the former secondary no-load voltage ratio of series transformer among Fig. 1, then according to transformer first-harmonic flux compensation principle, and the current i of injecting when Circuit Fault on Secondary Transformer _cBe primary side fundamental current i _Sf-during k times, the first-harmonic main flux of transformer is zero.At this moment, see into from the primary side of transformer that transformer presents very low primary side leakage impedance to first-harmonic, do not affect electrical network and normally move; And the n that the impedance that nth harmonic presents is about the first-harmonic excitation impedance doubly, transformer to the impedance of nth harmonic electric current much larger than the impedance to fundamental current, also much larger than the impedance of parallel resonance passive filter to the nth harmonic electric current, thereby force harmonic current to flow into the passive filtering branch road, and do not flow into grid side, play good harmonic wave buffer action.Series connection type active electric power filter mainly plays harmonic voltage and the electrical network background harmonics voltage in the compensating non-linear load, isolation load-side harmonic current, improve the effect of passive filter performance, it is to the generation of the high impedance energy establishment electrical network series and parallel resonance of harmonic wave simultaneously.PPF in parallel is the band stop filter of one group of parallel resonance, resonance is in fundamental frequency, be connected in parallel on load-side, very little to the high order harmonic component impedance, the low order characteristic harmonics had less impedance, be mainly load the harmonic current passage is provided, when load-side has the harmonic voltage distortion, can effectively limit the low-order harmonic size of current that flows through PPF, do not affect simultaneously filter effect, overcome the shortcoming of the easy overcurrent of harmonic wave among the PPF of traditional SHAPF, made wide frequency domain polymorphic type harmonic synthesis governing system can be used for the dissimilar harmonic sources of comprehensive compensation, can also compensate certain reactive power by adjusting resonance frequency.Hybrid Type Series Active Power Filter among Fig. 1 is wide frequency domain polymorphic type harmonic synthesis governing system.

As shown in Figure 2, series connection type active electric power filter adopts a kind of control method based on transformer first-harmonic flux compensation principle among the present invention, only need to control the fundamental current of voltage source inverter output, the control object frequency is single, and control simply is easy to realize.The present invention adopts electric current floating PI control, by coordinate transform the fundamental current error signal is become direct current signal, then direct current signal is carried out PI control, can eliminate the systematic steady state error.

In order to reduce the coordinate transform number of times, detection of grid current i at first _s, i.e. series transformer primary current, this electric current multiply by coefficient-k and obtains transformer secondary equivalent electric flow valuve, then deducts the inverter output current i that detects _c, the current i that obtains ₁In comprise the error signal of harmonic current, compensating fundamental wave current reference amount and actual offset current.In order to extract the compensating fundamental wave current error signal, according to instantaneous reactive power theory, the three-phase current signal that obtains is carried out i _p, i _qConversion, C among the figure _FTAnd C _ITBe respectively direct transform and inverse-transform matrix, obtain the instantaneous meritorious amount of first-harmonic through low-pass filtering

With idle amount

Calculate again the amplitude I of the fundamental current margin of error ₁And phase angle

Then only the amplitude of error current signal is carried out proportional plus integral control, thereby avoided the frequency of error signal and the integration of phase angle.And manipulated signal is DC quantity, can make the astatic tracking compensating fundamental wave of inverter output current current signal.In addition, can in the phase angle of signal, superpose one and adjust angle The phase delay that compensating signal detects and the output filtering link causes, or make the phase place of output fundamental current Phase Tracking line voltage by phase adjust, reach the purpose of compensating reactive power.As seen, use common PI controller to realize the advantage of improper integral device, reduced simultaneously the quantity of coordinate transform and PI controller, control algolithm is simple, is easy to realize.

Wherein, direct transform Matrix C _FTWith inverse-transform matrix C _ITExpression formula as follows:

$C_{\mathrm{FT}}=\frac{2}{3}\left[\begin{array}{cc}\sin \mathrm{\ω}t\sin (\mathrm{\ωt}-2\mathrm{\π}/3)& \sin (\mathrm{\ωt}+2\mathrm{\π}/3)\\ \cos \mathrm{\ω}t\cos (\mathrm{\ωt}-2\mathrm{\π}/3)& \cos (\mathrm{\ωt}+2\mathrm{\π}/3)\end{array}\right]---\left(1\right)$

$C_{\mathrm{IT}}=\left[\begin{array}{cc}\sin \mathrm{\ωt}& \cos \mathrm{\ωt}\\ \sin (\mathrm{\ωt}-2\mathrm{\π}/3)& \cos (\mathrm{\ωt}-2\mathrm{\π}/3)\\ \sin (\mathrm{\ωt}+2\mathrm{\π}/3)& \cos (\mathrm{\ωt}+2\mathrm{\π}/3)\end{array}\right]---\left(2\right)$

If:

ω is the first-harmonic angular frequency in the formula.Then can obtain:

$\left[\begin{array}{c}{i}_p\\ i_q\end{array}\right]=C_{\mathrm{FT}}\left[\begin{array}{c}{i}_{1a}\\ i_{1b}\\ i_{1c}\end{array}\right]---\left(3\right)$

Active current i _pWith reactive current component i _qThrough behind the low pass filter, can obtain their DC component and be respectively

With

By can be calculated:

The amplitude and the phase information that have comprised the compensating fundamental wave current error signal in the formula (4), by following formula can calculate its amplitude and phase place as follows:

Suppose to be respectively I through amplitude and the phase angle of the first-harmonic modulator control signal after PI controller and the phase place adjustment ^*With

Then can obtain exporting the instantaneous real component of fundamental current modulator control signal by simple calculating

And idle component

Be shown below:

Through inverse transformation, can obtain inverter output three-phase alternating current modulator control signal i by following formula ^*, as follows:

$i^{*}=\left[\begin{array}{c}{i}_a^{*}\\ i_b^{*}\\ i_c^{*}\end{array}\right]=C_{\mathrm{IT}}\left[\begin{array}{c}{i}_p^{*}\\ i_q^{*}\end{array}\right]---\left(7\right)$

Claims (7)

1. the control method of a wide frequency domain polymorphic type harmonic synthesis governing system, comprise wide frequency domain polymorphic type harmonic synthesis governing system, described wide frequency domain polymorphic type harmonic synthesis governing system comprises series connection type active electric power filter, passive power filter in parallel, described series connection type active electric power filter comprises inverter, filter circuit and transformer, described inverter is connected to the secondary of described transformer through filter circuit, the former limit of described transformer is connected in the power network line, the described series connection type active electric power filter load-side of described passive power filter in parallel access in parallel, it is characterized in that the method is:

1) detection of grid three-phase current i _Sa, i _Sb, i _Sc, the electrical network three-phase current be multiply by transformer primary secondary no-load voltage ratio K and anti-phase, namely multiply by-k, make to comprise secondary compensating fundamental wave current signal in the electric current that obtains;

2) current signal that step 1) is obtained deducts inverter output current i _Ca, i _Cb, i _Cc, obtain the compensating fundamental wave current error signal;

3) the compensating fundamental wave current error signal is carried out the ip-iq direct transform, and through low pass filter, extract the real component of error signal

And idle component

4) the amplitude I of calculating compensating fundamental wave current error signal ₁And phase angle

Amplitude is carried out PI regulate, phase angle is carried out compensation of delay, obtain the amplitude reference quantity

With the phase angle reference quantity

5) calculate current-modulation with reference to real component according to amplitude reference quantity and phase angle reference quantity

And idle component

6) carry out the ip-iq inverse transformation, obtain three-phase current modulator control signal i ^*, control voltage source inverter output compensating fundamental wave electric current.

2. the control method of wide frequency domain polymorphic type harmonic synthesis governing system according to claim 1 is characterized in that, described Parallel passive filter is the first-harmonic parallel resonance non active band exclusion filter that is made of inductance and electric capacity.

3. the control method of wide frequency domain polymorphic type harmonic synthesis governing system according to claim 1 is characterized in that, described inverter is three-phase voltage-type inverter.

4. the control method of wide frequency domain polymorphic type harmonic synthesis governing system according to claim 1 is characterized in that, described filter circuit is the LC output filter circuit.

5. the control method of wide frequency domain polymorphic type harmonic synthesis governing system according to claim 1 is characterized in that, the former secondary no-load voltage ratio of described series connection type active electric power filter is k:1.

6. the control method of wide frequency domain polymorphic type harmonic synthesis governing system according to claim 1 is characterized in that in the described step 5), current-modulation is with reference to real component

And idle component

Computing formula as follows:

Wherein,

7. according to claim 1 or the control method of 6 described wide frequency domain polymorphic type harmonic synthesis governing systems, it is characterized in that, in the described step 6), three-phase current modulator control signal i ^*Computing formula as follows:

$i^{*}=\left[\begin{array}{c}{i}_a^{*}\\ i_b^{*}\\ i_c^{*}\end{array}\right]=C_{\mathrm{IT}}\left[\begin{array}{c}{i}_p^{*}\\ i_q^{*}\end{array}\right],$

Wherein, $C_{\mathrm{IT}}=\left[\begin{array}{cc}\sin \mathrm{\ωt}& \cos \mathrm{\ωt}\\ \sin (\mathrm{\ωt}-2\mathrm{\π}/3)& \cos (\mathrm{\ωt}-2\mathrm{\π}/3)\\ \sin (\mathrm{\ωt}+2\mathrm{\π}/3)& \cos (\mathrm{\ωt}+2\mathrm{\π}/3)\end{array}\right],$ ω is the first-harmonic angular frequency in the formula.

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