CN104993487B - For the SAPF control methods of voltage-source type nonlinear load harmonic compensation - Google Patents

Abstract

The present invention relates to a kind of SAPF control methods for the compensation of voltage-source type nonlinear load harmonic, it comprises the following steps：Step 1, acquisition system voltage u_sSynchronizing signal θ_e；Step 2, PI voltage controllers generate the real power component P of harmonic wave instruction current_dc；Step 3, SAPF harmonic compensation instruction currents i is generated by Harmonic currents detection link_Lh ^*；Step 4, by harmonic voltage detection extract obtain PCC harmonic voltages u_sh；Step 5, the comprehensive harmonic wave instruction current i of generation_h ^*；Step 6, detection SAPF output compensation electric currents i_c, calculating current deviation Δ i=i_h ^*‑i_c, the current deviation value Δ i that will be obtained is input into PI current controllers, with by PI current controllers generation modulation wave voltage u；Step 7, the modulation wave voltage u to above-mentioned generation export PWM trigger pulses using space vector pulse width modulation mode.The present invention is easy to operate, can be effectively improved compensation effects of the SAPF to voltage-source type nonlinear load, suppresses the Current amplifier of voltage-source type nonlinear load, safe and reliable.

Description

For the SAPF control methods of voltage-source type nonlinear load harmonic compensation

Technical field

The present invention relates to a kind of control method, especially a kind of SAPF for the compensation of voltage-source type nonlinear load harmonic (Shunt Active Power Filter, SAPF) control method, belongs to the technical field of electrician's class power electronics.

Background technology

Active Power Filter-APF (Active Power Filter, APF) is used as a kind of advanced harmonic treating apparatus, energy It is enough effectively to suppress nonlinear load harmonic.However, correlative study in recent years finds, exist between APF and harmonic source and influence each other, In order to obtain preferable harmonic compensation effect, tandem type APF is suitable only for compensating voltage source type nonlinear load, and parallel connection type APF (Shunt APF, SAPF) is adapted for compensating for current source type nonlinear load.When SAPF is non-linear for compensating voltage source type During load, the voltage ripple and ac-side current peak value of rectifier DC side can be increased.

In order to improve SAPF (Shunt Active Power Filter, SAPF) to voltage-source type nonlinear load Compensation effect, suppresses load harmonic current and amplifies, as long as existing technology is divided into two classes：One class is change system resonance frequencies model There is engineer applied inconvenience and increase in the method enclosed, the method mainly in load AC current-limiting reactor or shnt capacitor The problems such as oil (gas) filling device volume and cost；Another kind of to compensate two methods of bandwidth to change SAPF, the method is by overtone order Selectivity compensation eliminate source of resonant excitation, but reduce harmonic compensation effect.

The content of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, there is provided one kind is used for voltage-source type nonlinear load The SAPF control methods of harmonic compensation, its is easy to operate, can be effectively improved compensation effects of the SAPF to voltage-source type nonlinear load Really, the Current amplifier of voltage-source type nonlinear load is suppressed, it is safe and reliable.

According to the technical scheme that the present invention is provided, a kind of SAPF controls for the compensation of voltage-source type nonlinear load harmonic Method, the control method of the SAPF comprises the following steps：

Step 1, the points of common connection PCC for voltage-source type nonlinear load and SAPF wave filters, detect and obtain institute State the system voltage u of points of common connection PCC_s；Obtaining the system voltage u of points of common connection PCC_sObtained by PLL phaselocked loops afterwards The system voltage u_sSynchronizing signal θ_e；

Step 2, the magnitude of voltage U for detecting and obtaining SAPF DC sides_dc, and by the magnitude of voltage U_dcWith command voltageThan Compared with, and by magnitude of voltage U_dcWith command voltageResult after comparing is input into PI voltage controllers, PI voltage controllers according to Magnitude of voltage U_dcWith command voltageResult of the comparison generates the real power component P of harmonic wave instruction current_dc；

Step 3, the load current i for obtaining voltage-source type nonlinear load_L, and by load current i_L, harmonic wave instruction current Real power component P_dcAnd synchronizing signal θ_eIn input to Harmonic currents detection link, given birth to by Harmonic currents detection link Into SAPF harmonic compensation instruction currents i_Lh ^*；

Step 4, by system voltage u_sInput is extracted to harmonic voltage detection with by harmonic voltage detection To PCC harmonic voltages u_sh；

Step 5, by PCC harmonic voltages u_shBe multiplied by proportionality coefficient-k, and with SAPF harmonic wave instruction currents i_Lh ^*It is superimposed, it is raw Into comprehensive harmonic wave instruction current i_h ^*, the comprehensive harmonic wave instruction current i_h ^*For：

Step 6, the compensation electric current i for obtaining SAPF outputs_c, to obtain current deviation value Δ i：

Δ i=i_h ^*-i_c,

The current deviation value Δ i that will be obtained is input into PI current controllers, and modulating wave is generated with by PI current controllers Voltage u, PI current controller generation modulation wave voltage u be：

Wherein, k_p、k_iThe respectively ratio and integral constant of PI current controllers；

Step 7, the modulation wave voltage u to above-mentioned generation export PWM trigger pulses using space vector pulse width modulation mode, With by the switch of PWM trigger pulse triggers SAPF.

PI voltage controllers are according to magnitude of voltage U_dcWith command voltageThe harmonic wave instruction current of result of the comparison generation Real power component P_dcFor：

Wherein, k_pdc、k_idcThe respectively ratio and integral constant of PI voltage controllers.

Advantages of the present invention：

1st, it is compared to the existing change system resonance by load AC current-limiting reactor or shnt capacitor frequently The method of rate scope, the inventive method reduces the volume and cost of device without current-limiting reactor or shnt capacitor, is easy to Engineer applied, and eliminate problem and series connection that the larger capacitive reactive power electric current of shnt capacitor generation causes system overcompensation The load side voltage landing problem that reactor is produced；

2nd, the method that existing change SAPF compensates bandwidth is compared to, the inventive method uses load harmonic current and PCC Harmonic voltage co- controlling SAPF output harmonic waves compensate electric current, are equivalent at PCC virtual a harmonic wave resistance, Neng Gouyou in parallel Effect suppresses amplified harmonic current, without changing harmonic compensation bandwidth, so that with more excellent harmonic compensation effect.

Brief description of the drawings

Fig. 1 is the circuit theory diagrams that existing SAPF is compensated voltage-source type nonlinear load.

Fig. 2 is circuit theory diagrams of the invention.

Fig. 3 is single-phase harmonic wave equivalent circuit diagram of the invention.

Fig. 4 is experimental waveform figure when existing use SAPF is compensated voltage-source type nonlinear load.

Fig. 5 is that existing use SAPF is compensated voltage-source type nonlinear load and the experiment when AC string inductance is loaded Oscillogram.

Fig. 6 is that existing use SAPF is compensated voltage-source type nonlinear load and when AC shnt capacitor is loaded Experimental waveform figure.

Fig. 7 is experimental waveform figure of the invention.

Description of reference numerals：100-SAPF wave filters, 110- voltage comparators, 120-PI voltage controllers, 130- harmonic waves Current detecting link, 140-PLL phaselocked loops, 150- harmonic voltages detection, 160- proportional components, the electric currents of 170- first compare Device, the current comparators of 180- second, 190-PI current controllers and 200-SVPWM modules.

Specific embodiment

With reference to specific drawings and Examples, the invention will be further described.

As shown in Figure 1：It is the circuit theory diagrams that existing utilization SAPF is compensated voltage-source type nonlinear load, SAPF filtering Device 100 uses three-phase bridge rectifier structure, electric capacity C_f, inductance L be respectively DC bus capacitor and net side filter inductance；Voltage-source type Nonlinear load is three-phase uncontrollable rectifier bridge, and the DC side filter element of voltage-source type nonlinear load is electric capacity C_d, R_LFor equivalent Ohmic load；u_gIt is line voltage, R_g、L_gIt is the equivalent resistance sense of power network；i_s、i_c、i_LRespectively system harmonicses electric current, SAPF compensation is electric Stream and load current.

As shown in Fig. 2 being circuit theory diagrams when SAPF that the present invention carries out harmonic compensation is controlled, voltage-source type is non-linear Load with SAPF wave filters 100 there is points of common connection PCC, PLL phaselocked loop 140, harmonic voltage detection 150 to be both connected to At points of common connection PCC, the output end of PLL phaselocked loops 140 is connected with the input of Harmonic currents detection link 120, harmonic wave electricity Stream detection 120 also receives load current i_LInput and PI voltage controllers 120 generation harmonic wave instruction current it is active Power component P_dc.PI voltage controllers 120 are connected with the output end of voltage comparator 110, and voltage comparator 110 filters SAPF The magnitude of voltage U of the DC side of device 100_dcWith command voltageIt is compared, and result of the comparison is transmitted to PI voltage controllers In 120.Voltage u of the harmonic voltage detection 150 to points of common connection PCC_sBody area harmonic wave, to obtain PCC harmonic voltages u_sh。 The output end of harmonic voltage detection 150 is connected with proportional component 160, the output end and harmonic current of proportional component 160 The output end of detection 130 is connected with the first current comparator 170, the output end and second of the first current comparator 170 The input connection of current comparator 180, the second current comparator 180 is connected with PI current controllers 190, PI current controllers 190 are connected with SVPWM modules 200, the PWM trigger pulses of the output control SAPF filter switches of SVPWM modules 200 work.

Coordinated by above-mentioned connection, the present invention primarily forms Harmonic currents detection, the detection of PCC harmonic voltages, current tracking Control, SAPF DC voltage controls and pulse modulated five parts of SVPWM, in the embodiment of the present invention, using load electricity Stream i_LWith PCC harmonic voltages u_shThe output SAPF compensation electric currents of co- controlling SAPF wave filters 100 i_c.Fig. 3 is the equivalent circuit of Fig. 2 Figure, it is equivalent at points of common connection PCC a virtual harmonic wave resistance in parallel.In Fig. 3, I_shIt is system harmonicses electric current；It is preferable Harmonic voltage source U_LhWith Equivalent Harmonic impedance Z_LhSeries connection represents voltage-source type nonlinear load, I_LhIt is load harmonic current；SAPF Wave filter 100 is equivalent to controlled harmonic current source, uses I_chRepresent, I_ch=λ I_Lh,；U_shIt is points of common connection harmonic voltage.Harmonic wave Voltage adoption rate is controlled, and proportionality coefficient is set to k, then Equivalent Harmonic resistance is 1/k.SAPF wave filters 100 are due to generally use Direct output current control model, therefore, SAPF wave filters 100 can be equivalent to controlled current source, by SAPF wave filters 100 etc. The mode in controlled current source is imitated known to those skilled in the art, here is omitted.

According to Fig. 2, Fig. 3 and described above, the control method of SAPF of the present invention comprises the following steps：

Step 1, the points of common connection PCC for voltage-source type nonlinear load and SAPF wave filters 100, detect and obtain The system voltage u of the points of common connection PCC_s；Obtaining the system voltage u of points of common connection PCC_sPass through PLL phaselocked loops afterwards 140 obtain the system voltage u_sSynchronizing signal θ_e；

In the embodiment of the present invention, the system voltage u of points of common connection PCC is obtained by conventional technology_s, obtaining The system voltage u of points of common connection PCC_sAfterwards, system voltage u is obtained by PLL phaselocked loops 140 by conventional technology_sIt is same Step signal θ_e, whole process is known to those skilled in the art, and here is omitted.

Step 2, the magnitude of voltage U for detecting and obtaining SAPF DC sides_dc, and by the magnitude of voltage U_dcWith command voltageThan Compared with, and by magnitude of voltage U_dcWith command voltageResult after comparing is input into PI voltage controllers 120, PI voltage controllers 120 according to magnitude of voltage U_dcWith command voltageResult of the comparison generates the real power component P of harmonic wave instruction current_dc；

In the embodiment of the present invention, by detecting electric capacity C_fThe voltage of both sides obtains the voltage of the DC side of SAPF wave filters 100 Value U_dc, command voltageIt is control targe value, command voltageSize according to control targe determine, determine instruction voltageProcess for known to those skilled in the art, here is omitted.Magnitude of voltage U_dcWith command voltageBy voltage ratio compared with Device 110 is compared, and the comparison procedure of voltage comparator 100 is command voltageWith magnitude of voltage U_dcBetween difference.

PI voltage controllers 120 are according to magnitude of voltage U_dcWith command voltageThe harmonic wave instruction current of result of the comparison generation Real power component P_dcFor：

Wherein, k_pdc、k_idcThe respectively ratio and integral constant of PI voltage controllers 120.In PI voltage controllers 120 Proportionality constant k_pdc, integral constant k_idcSize can be determined according to experiment, specially known to those skilled in the art.

Step 3, the load current i for obtaining voltage-source type nonlinear load_L, and by load current i_L, harmonic wave instruction current Real power component P_dcAnd synchronizing signal θ_eIn input to Harmonic currents detection link 130, with by Harmonic currents detection ring Section 130 generates SAPF harmonic compensation instruction currents i_Lh ^*；

In the embodiment of the present invention, the load current of voltage-source type nonlinear load can be obtained by conventional technology i_L, the load current i of Harmonic currents detection link 130_L, harmonic wave instruction current real power component P_dcAnd synchronizing signal θ_eAltogether With generation SAPF harmonic compensation instruction currents i_Lh ^*, the determination generation SAPF harmonic compensation instruction currents of Harmonic currents detection link 130 i_Lh ^*Process for known to those skilled in the art, here is omitted.

Step 4, by system voltage u_sIt is input into harmonic voltage detection 150, with by harmonic voltage detection 150 Extraction obtains PCC harmonic voltages u_sh；

In the embodiment of the present invention, harmonic voltage detection 150 is extracted by conventional technology and obtains system voltage u_sPCC harmonic voltages u_sh, specific extraction process is that here is omitted known to those skilled in the art.

Step 5, by PCC harmonic voltages u_shBe multiplied by proportionality coefficient-k, and with SAPF harmonic wave instruction currents i_Lh ^*It is superimposed, it is raw Into comprehensive harmonic wave instruction current i_h ^*, the comprehensive harmonic wave instruction current i_h ^*For：

In the embodiment of the present invention, the output end of harmonic voltage detection 150 is connected with proportional component 160, passing ratio Link 160 is by PCC harmonic voltages u_shProportionality coefficient-k is multiplied by, by the first current comparator 170 by SAPF harmonic wave instruction currents i_Lh ^*、ku_shIt is overlapped, by obtaining comprehensive harmonic wave instruction current i after the superposition of the first current comparator 170_h ^*.Usually, than The absolute value of the proportionality coefficient-k of example link 160 is bigger, better to harmonics restraint, and the proportionality coefficient-k of proportional component 160 determines Process is that here is omitted known to those skilled in the art.

Step 6, the compensation electric current i for obtaining SAPF outputs_c, to obtain current deviation value Δ i：

Δ i=i_h ^*-i_c,

The current deviation value Δ i that will be obtained is input into PI current controllers 190, is generated with by PI current controllers 190 The modulation wave voltage u of the generation of modulation wave voltage u, PI current controller 190 is：

Wherein, k_p、k_iThe respectively ratio and integral constant of PI current controllers 190；

In the embodiment of the present invention, the SAPF compensation electricity of the output of SAPF wave filters 100 is obtained by conventional technology Stream i_c, the second current comparator 180 is to SAPF compensation electric currents i_cAnd comprehensive harmonic wave instruction current i_h ^*It is compared, the knot for comparing Fruit is input into PI current controllers 190.PI current controllers 190 obtain modulation wave voltage u, PI electricity according to current deviation value Δ i Proportionality constant k in stream controller 190_p, integral constant k_iCan specifically be determined by technological means such as experience, experiments, it is specific to determine Process determines for those skilled in the art.

Step 7, the modulation wave voltage u to above-mentioned generation export PWM trigger pulses using space vector pulse width modulation mode, With by the switch of PWM trigger pulse triggers SAPF.

In the embodiment of the present invention, after modulation wave voltage u is determined by PI current controllers 190, modulation wave voltage u is passed Transport in SVPWM modules 200, exported using space vector pulse width modulation mode by 200 couples of upper modulation wave voltage u of SVPWM modules PWM trigger pulses.

After undergoing the above-described steps, SAPF wave filters 100 have actually carried out to voltage-source type nonlinear load humorous Ripple is compensated, when to harmonic compensation, SAPF compensation electric currents i_cTo SAPF harmonic compensation instruction currents i_Lh ^*Compared by the first electric current Device 170, the second current comparator 180 and PI current controllers 190 carry out accurate tracking.Under normal circumstances, SAPF wave filters 100 pairs of voltage-source type nonlinear loads carry out harmonic compensation, can increase the amplification for causing load harmonic current.Passing ratio of the present invention Link 160 increased PCC harmonic voltages u_shFeedback control link (feedback factor be-k) such that it is able to effectively suppress SAPF filters Ripple device 100 causes the amplification to load harmonic current when harmonic compensation is carried out to voltage-source type nonlinear load, and improves humorous Ripple compensation effect.

In the embodiment of the present invention, for foregoing circuit and rate-determining steps, the specific value of different piece is：

In order to be able to illustrate validity of the present invention to the compensation of voltage-source type nonlinear load harmonic, can be by following several Contrast test carries out comparative illustration, specially：

1) the humorous of any control measure is provided without when, SAPF wave filters 100 are compensated voltage-source type nonlinear load harmonic Ripple compensation experiment, i.e., just with SAPF wave filters 100 to the harmonic compensation of power line nonlinear load, result of the test such as Fig. 4 It is shown.As seen from the figure, after SAPF wave filters 100 start, load current i_LIt is exaggerated, 115A of the current peak from before startup reaches 236A, Harmonics amplification multiple is up to 105%.Additionally, system harmonicses electric current i_sTotal harmonic distortion THD=24.8%.

2) SAPF harmonic compensations when, using load AC string inductive methods are tested, as shown in Figure 5.Serial inductance It is 150 μ H.Load current i after the startup of SAPF wave filters 100_L90A of the peak value from before startup rises to 106A, Harmonics amplification times Number is reduced to 17.8%；System harmonicses electric current i_sTHD=7.9%.It can be seen that, the method effectively inhibits load harmonic current to put Greatly, improve harmonic current compensation effect.

3) SAPF harmonic compensations when, using load AC shnt capacitor method are tested, as shown in Figure 6.Electricity in parallel Capacitance is 5mF.Observation experiment waveform, after startup, load current i_L115A of the peak value from before startup rises to 139A, Harmonics amplification Multiple is reduced to 20.8%, system harmonicses electric current i_sTHD=1.7%.Relative to AC string inductive methods, it is under the method System harmonic current i_sTotal harmonic distortion is smaller, and mainly shunt capacitance plays filter action with line impedance.

Above two Traditional solutions, when continuing to increase load AC series inductance or parallel capacitance of value, effect More improvement are had, the effect of wherein tandem electric inductance is more obvious.But with the increase of inductance and electric capacity value, on the one hand set Standby volume and cost increase, and bring larger power attenuation；On the other hand, big inductance causes load side voltage to land, and influence sets Standby efficiency, and capacitor can increase the capacitive reactive power of system, this point from Fig. 6 this it appears that.

4) SAPF harmonic compensations when, using using Novel Control of the present invention, as shown in Figure 7.Proportional component 160 proportionality coefficient k absolute values take 20.As seen from the figure, the load current i after startup_L115A of the peak value from before startup rises to 119A, Harmonics amplification multiple is reduced to 3.5%；System harmonicses electric current i_sTHD=3.1%.It can be seen that, the present invention is relative to above-mentioned two Traditional solution is planted, in the case of without hardware devices such as inductance and capacitors, preferable harmonics restraint can be obtained Effect.

Claims (2)

1. it is a kind of for voltage-source type nonlinear load harmonic compensation SAPF control methods, it is characterized in that, the control of the SAPF Method processed comprises the following steps：

Step 1, the points of common connection PCC for voltage-source type nonlinear load and SAPF wave filters, detect and obtain the public affairs The system voltage u of common tie point PCC_s；Obtaining the system voltage u of points of common connection PCC_sObtain described by PLL phaselocked loops afterwards System voltage u_sSynchronizing signal θ_e；

Step 2, the magnitude of voltage U for detecting and obtaining SAPF DC sides_dc, and by the magnitude of voltage U_dcWith command voltageCompare, and By magnitude of voltage U_dcWith command voltageResult after comparing is input into PI voltage controllers, and PI voltage controllers are according to voltage Value U_dcWith command voltageResult of the comparison generates the real power component P of harmonic wave instruction current_dc；

Step 3, the load current i for obtaining voltage-source type nonlinear load_L, and by load current i_L, harmonic wave instruction current it is active Power component P_dcAnd synchronizing signal θ_eIn input to Harmonic currents detection link, generated with by Harmonic currents detection link SAPF harmonic compensation instruction currents i_Lh ^*；

Step 4, by system voltage u_sInput obtains PCC to harmonic voltage detection to be extracted by harmonic voltage detection Harmonic voltage u_sh；

Step 5, by PCC harmonic voltages u_shBe multiplied by proportionality coefficient-k, and with SAPF harmonic wave instruction currents i_Lh ^*It is superimposed, generate comprehensive Close harmonic wave instruction current i_h ^*, the comprehensive harmonic wave instruction current i_h ^*For：

$i_h^{*}=i_{Lh}^{*}-{\mathrm{ku}}_{sh};$

Step 6, the compensation electric current i for obtaining SAPF outputs_c, to obtain current deviation value Δ i：

Δ i=i_h ^*-i_c,

The current deviation value Δ i that will be obtained is input into PI current controllers, and modulation wave voltage is generated with by PI current controllers U, PI current controller generation modulation wave voltage u be：

$u=(K_p+\frac{K_i}{s})\×({i_h}^{*}-i_c),$

Wherein, K_p、K_iThe respectively ratio and integral constant of PI current controllers；

Step 7, the modulation wave voltage u to above-mentioned generation export PWM trigger pulses using space vector pulse width modulation mode, with logical Cross the switch of PWM trigger pulse triggers SAPF.

2. it is according to claim 1 for voltage-source type nonlinear load harmonic compensation SAPF control methods, its feature It is：PI voltage controllers are according to magnitude of voltage U_dcWith command voltageThe wattful power of the harmonic wave instruction current of result of the comparison generation Rate component P_dcFor：

$P_{dc}=(K_{pdc}+\frac{K_{idc}}{s})\×(U_{dc}^{*}-U_{dc})$

Wherein, K_pdc、K_idcThe respectively ratio and integral constant of PI voltage controllers.