CN103036236B - 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 range multi-type harmonic comprehensive governance system

Technical field

The present invention relates to Active Power Filter-APF, particularly a kind of control method of wide frequency range multi-type harmonic comprehensive governance system.

Background technology

Along with being on the increase of power electronic equipment application, harmonic source kind increases, and mains by harmonics environment becomes increasingly complex.Electrical network rectifying device is a kind of typical harmonic source, according to the difference of its DC side filter element, can be roughly divided into current mode harmonic source and voltage-type harmonic source two kinds.DC side adopts the rectifying device of inductor filter can regard current mode harmonic source as, and DC side is that the rectifying device of capacitor filtering can regard voltage-type harmonic source as.Because early stage current mode rectifying device application is comparatively extensive, 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, increasing along with the application of the power electronic equipment such as frequency converter, Switching Power Supply, uninterrupted power supply and electric ballast, in electrical network, voltage-type harmonic source is on the increase, and becomes another kind of main harmonic source.And may not only contain current mode harmonic source but also have voltage-type harmonic source in some occasion loads, harmonic problem be serious, needs to carry out the comprehensive regulation to dissimilar harmonic source.

At present, a lot of research is carried out to the administering method of current mode, voltage-type harmonic source both at home and abroad, and little to the research of dissimilar harmonic source comprehensive processing method.Some research conclusions show that parallel connection type active electric filter is applicable to offset current type harmonic source, series connection type active electric power filter is applicable 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, capital causes Harmonics amplification phenomenon, and compensation effect is all bad.Traditional Hybrid Type Series Active Power Filter can offset current type harmonic source, but passive part generally adopts many group single tandem resonance passive power filters, when load-side contains harmonic voltage, easily cause the harmonic current flowing through passive power filter excessive, be therefore not suitable for the occasion that load-side has harmonic voltage distortion.The hybrid passive filter be made up of series passive filter and Parallel passive filter, the comprehensive compensation to voltage-type and current mode harmonic wave can be realized, but the filter off-tune that the change of series resonance passive filter parameters and mains frequency deviation cause adds the impact of upper filter internal resistance, larger fundamental voltage landing may be produced, affect electrical network and normally run.Conventional serial type Active Power Filter-APF adopts and detects load voltage, detect the control method such as source current, compound detection due to the direct harmonic signal to different frequency unifies to control, the error of amplitude and phase place is easily produced during stable state, and this error not easily adjusts and corrects, 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 range multi-type harmonic comprehensive governance system is provided, realize the comprehensive regulation to current mode and voltage-type harmonic source, effective suppression mains by harmonics series and parallel resonance, 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 range multi-type harmonic comprehensive governance system, comprise wide frequency range multi-type harmonic comprehensive governance system, described wide frequency range multi-type harmonic comprehensive governance system comprises series connection type active electric power filter, parallel passive electric-power filter, 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 power network line, the described series connection type active electric power filter load-side of described parallel passive electric-power filter parallel connection access, the method is:

1) detection of grid three-phase current i _sa, i _sb, i _sc, electrical network three-phase current is multiplied by transformer primary secondary no-load voltage ratio and anti-phase, is namely multiplied by-k, makes in the electric current obtained, to comprise secondary compensating fundamental wave current signal;

2) current signal that step 1) obtains is deducted inverter output current i _ca, i _cb, i _cc, obtain compensating fundamental wave current error signal;

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

4) the amplitude I of compensating fundamental wave current error signal is calculated ₁and phase angle pI adjustment is carried out to amplitude, compensation of delay is carried out to phase angle, obtain the reference quantity of amplitude and phase angle with

5) according to the reference quantity calculating current modulation reference real component of amplitude and phase angle and idle component

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

Described Parallel passive filter is the first-harmonic parallel resonance non active band exclusion filter be made up 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 high order harmonic component impedance, to low order characteristic harmonics, there is less impedance, when load-side has harmonic voltage distortion, effectively can limit the low-order harmonic size of current flowing through PPF, not affect current harmonics elimination effect simultaneously.And wide frequency range multi-type harmonic comprehensive governance system is applied to occasion that load-side has harmonic voltage distortion, achieve the comprehensive compensation to current mode and voltage-type harmonic source; Adopt the control method based on transformer fundamental flux compensation principle, injecting a size at transformer secondary is the power network current k doubly contrary compensating fundamental wave electric current in direction, series transformer is made to be zero to impedance of fundamental frequency, do not affect electrical network normally to run, very high impedance is presented to harmonic wave simultaneously, the filter effect of passive power filter can be improved, compensation harmonic voltage, well suppress mains by harmonics series and parallel resonance simultaneously; Serial active filter compensating fundamental wave electric current adopts astatic PI control method, only proportional plus integral control is carried out to the amplitude of command signal, and do not affect its phase place, have dynamic property good, fix without steady-state error, switching frequency, be simple and easy to the advantage that realizes.

Accompanying drawing explanation

Fig. 1 is the topology diagram of one embodiment of the invention wide frequency range multi-type harmonic comprehensive governance system;

Fig. 2 is the detection control block diagram of one embodiment of the invention wide frequency range multi-type harmonic comprehensive governance system.

Embodiment

As shown in Figure 1, one embodiment of the invention wide frequency range multi-type harmonic comprehensive governance system comprises series connection type active electric power filter and Parallel Resonant passive filter, Parallel Resonant passive filter is the first-harmonic parallel resonance non active band exclusion filter be made up of inductance and electric capacity, series connection type active electric power filter by each cross streams output of three-phase voltage-type inverter after a LC output filter circuit, be connected to one end of series transformer secondary, wherein the electric capacity of LC output filter circuit is in parallel with transformer secondary, series transformer on electrical network three-phase adopts Y type to connect, the series transformer secondary other end is as three-phase neutral point, the former limit of series transformer is then connected between electrical network and harmonic source, the described series connection type active electric power filter load-side of Parallel Resonant passive power filter parallel connection access.In the present invention, Series active power filter adopts the control method based on transformer fundamental flux compensation principle, and the former secondary no-load voltage ratio as series transformer in Fig. 1 is k, then according to transformer fundamental flux compensation principle, when the current i that Circuit Fault on Secondary Transformer is injected _cfor primary side fundamental current i _sf-k times time, the first-harmonic main flux of transformer is zero.Now, enter viewed from the primary side of transformer, transformer presents very low primary side leakage impedance to first-harmonic, does not affect electrical network and normally runs; And the n of first-harmonic excitation impedance is about doubly to the impedance that nth harmonic presents, 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 nth harmonic electric current, thus force harmonic current to flow into 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 in compensating non-linear load and electrical network background harmonic voltage, isolation load-side harmonic current, improve the effect of passive filter performance, it effectively can suppress the generation of electrical network series and parallel resonance to the high impedance 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 high order harmonic component impedance, to low order characteristic harmonics, there is less impedance, be mainly load and harmonic current passage is provided, when load-side has harmonic voltage distortion, effectively can limit the low-order harmonic size of current flowing through PPF, do not affect filter effect simultaneously, overcome the shortcoming of the easy overcurrent of harmonic wave in the PPF of traditional SHAPF, make wide frequency range multi-type harmonic comprehensive governance system can be used for the dissimilar harmonic source of comprehensive compensation, certain reactive power can also be compensated by adjustment resonance frequency.Hybrid Type Series Active Power Filter in Fig. 1 and wide frequency range multi-type harmonic comprehensive governance system.

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

In order to reduce coordinate transform number of times, first detection of grid current i _s, i.e. series transformer primary current, this electric current is multiplied by coefficient-k and obtains transformer secondary equivalent current values, then deducts the inverter output current i detected _c, the current i obtained ₁in comprise the error signal of harmonic current, compensating fundamental wave current reference amount and actual offset current.In order to extract compensating fundamental wave current error signal, according to instantaneous reactive power theory, i is carried out to the three-phase current signal obtained _p, i _qconversion, C in figure _fTand C _iTbe respectively direct transform and inverse-transform matrix, obtain first-harmonic instantaneous active amount through low-pass filtering with idle amount calculate the amplitude I of the fundamental current margin of error again ₁and phase angle then only proportional plus integral control is carried out to the amplitude of error current signal, thus the integration of the frequency avoided error signal and phase angle.And manipulated signal is DC quantity, inverter output current astatic tracking compensating fundamental wave current signal can be made.In addition, an adjustment angle can be superposed in the phase angle of signal the phase delay that compensating signal detects and output filtering link causes, or the phase place of output fundamental current Phase Tracking line voltage is made by phase adjust, reach the object of compensating reactive power.Visible, use common PI controller to achieve the advantage of Generalized Integrator, decrease the quantity of coordinate transform and PI controller simultaneously, 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: in formula, ω is first-harmonic angular frequency.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 _qafter low pass filter, their DC component can be obtained and be respectively with by can be calculated:

Contain amplitude and the phase information of compensating fundamental wave current error signal in formula (4), its amplitude can be calculated by above formula and phase place as follows:

Suppose that amplitude and the phase angle of the fundamental modulation control signal after PI controller and phase place adjustment are respectively I ^*with then calculate the instantaneous active component that can obtain exporting fundamental current modulator control signal by simple and idle component be shown below:

By above formula through inverse transformation, inverter can be obtained and export three-phase alternating current modulator control signal i ^*, 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 (6)

1. the control method of a wide frequency range multi-type harmonic comprehensive governance system, comprise Hybrid Type Series Active Power Filter, described Hybrid Type Series Active Power Filter comprises series connection type active electric power filter, parallel passive electric-power filter, described Series active power filter comprises inverter, filter circuit and series transformer, described inverter is connected to the secondary of series transformer through filter circuit, the former limit of transformer is connected in power network line, the described series connection type active electric power filter load-side of described parallel passive electric-power filter parallel connection access, described Parallel passive filter is the first-harmonic parallel resonance non active band exclusion filter be made up of inductance and electric capacity, it is characterized in that, the method is:

1) detection of grid three-phase current i _sa, i _sb, i _sc, electrical network three-phase current is multiplied by transformer primary secondary no-load voltage ratio K and anti-phase, is namely multiplied by-k, makes in the electric current obtained, to comprise secondary compensating fundamental wave current signal;

2) by step 1) current signal that obtains deducts inverter output current i _ca, i _cb, i _cc, obtain compensating fundamental wave current error signal;

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

4) the amplitude I of compensating fundamental wave current error signal is calculated ₁and phase angle pI adjustment is carried out to amplitude, compensation of delay is carried out to phase angle, obtain amplitude reference amount with phase angle reference quantity

5) according to amplitude reference amount and phase angle reference quantity calculating current modulation reference real component and idle component

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

2. the control method of wide frequency range multi-type harmonic comprehensive governance system according to claim 1, is characterized in that, described inverter is three-phase voltage-type inverter.

3. the control method of wide frequency range multi-type harmonic comprehensive governance system according to claim 1, is characterized in that, described filter circuit is LC output filter circuit.

4. the control method of wide frequency range multi-type harmonic comprehensive governance 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.

5. the control method of wide frequency range multi-type harmonic comprehensive governance system according to claim 1, is characterized in that, described step 5) in, current-modulation is with reference to real component and idle component computing formula as follows:

Wherein,

6. the control method of wide frequency range multi-type harmonic comprehensive governance system according to claim 1 or 5, is characterized in that, described step 6) in, 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, $C_{\mathrm{IT}}=\left[\begin{array}{cc}\sin \mathrm{\ωt}& \cos \mathrm{\ωt}\\ \sin (\mathrm{\ωt}-2\mathrm{\π}/3)& \cos (\mathrm{\ωt}-2\mathrm{\π}/3)\\ \sin (\mathrm{\ωt}+2\mathrm{\π}/3)& \cos (\mathrm{\ωt}+2\mathrm{\π}/3)\end{array}\right],$ In formula, ω is first-harmonic angular frequency.