CN106451494A - Active damping control method based on grid-side current feedback - Google Patents

Abstract

The invention discloses an active damping control method based on grid-side current feedback. The active damping control method comprises the following steps: 1) calculating grid-side current instruction values is alpha_ref and is beta_ref in a two-phase static coordinate system; calculating grid-side current actual values is alpha and is beta of a grid-connected system of a three-phase alternating-current voltage source inverter in the two-phase static coordinate system; 2) calculating modulating wave initial instructions vma0_ref, vmb0_ref and vmc0_ref of the voltage source inverter; 3) calculating active damping control signals vad_a, vad_b and vad_c; and 4) obtaining modulating wave instruction values of the voltage source inverter according to the modulating wave initial instructions vma0_ref, vmb0_ref and vmc0_ref of the voltage source inverter and the active damping control signals vad_a, vad_b and vad_c, and then controlling each switching device in the voltage source inverter according to the modulating wave instruction values of the voltage source inverter. According to the method, LCL resonance oscillation can be inhibited, the reliability of the grid-connected system of the three-phase alternating-current voltage source inverter is improved, and the cost is low.

Description

A kind of active damping control method based on current on line side feedback

Technical field

The invention belongs to automatically controlling and the research field such as new energy power generation grid-connection system stability, it is related to a kind of based on net The active damping control method of side current feedback.

Background technology

In recent years, along with increasingly serious the problems such as the fast development of China's economy, energy shortage and environmental pollution.In order to Solve the above problems, the regenerative resource with wind-power electricity generation, photovoltaic generation as representative has obtained large-scale exploitation, so as to So that the grid-connected voltage source type inverter for accessing generation of electricity by new energy required for electrical network is obtained a wide range of applications.Voltage-source type is inverse Becoming device mostly coordinates PWM strategy to be operated using full-control type power electronic switching device.Therefore, it is to improve grid entry point The quality of power supply, reduces switch time ripple, and the wave filter between inverter and electrical network is just essential.With traditional L-type wave filter Compare, LCL type wave filter can provide more outstanding switch time Ripple Suppression ability in the case that volume and capacity are suitable. This feature causes which to save cost and floor space while the grid entry point quality of power supply is ensured, so as to obtain engineer applied Favor.But the resonance characteristic of LCL filter causes the design of the grid-connected inverter system of stable operation to become more difficult With complexity.

Recently, both at home and abroad two classes can be largely classified into the method for suppressing LCL filter resonance：Passive damping and active resistance Buddhist nun's control method.Wherein, the mode of passive damping is by directly serial or parallel connection access passive resistance in filter network, is somebody's turn to do Method is realized simply, and reliability is high and robustness is stronger, but the method can produce extra loss, especially in high-power Occasion, the loss can also bring the problem in terms of radiating.For active damping method, which can be divided into two classes again：Based on numeral filter The active damping of ripple and the active damping based on state variable feedback, based on the active damping method of digital filtering be by control Digital filter being introduced directly in loop processed and reaching the purpose for filtering LCL resonance peak, such method control structure is simple, and is not required to Extra sensor.But designing the digital filter needs known system parameters, and damping is to the change of systematic parameter extremely Sensitivity, therefore system stability is poor, based on the active damping method of state variable feedback be by detection filter network State variable forms active damping feedback circuit, and the method does not produce excess loss and strong robustness, at present, based on capacitance current The active damping method of feedback because damping controller simple structure, method for designing is ripe and be widely used.However, such is active Damping method needs extra high-precision sensor to detect capacitance current, so as to reduce whole system while cost is increased The reliability of system.

Content of the invention

It is an object of the invention to overcoming the shortcoming of above-mentioned prior art, there is provided a kind of having based on current on line side feedback Source damping control method, the method can suppress LCL resonance, improve stablizing for three-phase alternating current potential source type grid-connected inverters system Property, and low cost.

For reaching above-mentioned purpose, the active damping control method based on current on line side feedback of the present invention includes following Step：

1) three-phase alternating current potential source type grid-connected inverters system point of common coupling voltage v is detected_sa、v_sbAnd v_sc, according to three-phase Alternating-current voltage source type grid-connected inverters system point of common coupling voltage v_sa、v_sbAnd v_scCalculate net side electricity under two-phase rest frame Stream command value i_{sα_ref}And i_{sβ_ref}；The current on line side i of three-phase alternating current potential source type grid-connected inverters system is detected again_sa、i_sbAnd i_sc, further according to the current on line side i of three-phase alternating current potential source type grid-connected inverters system_sa、i_sbAnd i_scCalculate two-phase rest frame The current on line side actual value i of lower three-phase alternating current potential source type grid-connected inverters system_sαAnd i_sβ；

2) by step 1) net side of three-phase alternating current potential source type grid-connected inverters system under the two-phase rest frame that obtains Current instruction value i_{sα_ref}And i_{sβ_ref}Respectively with three-phase alternating current potential source type grid-connected inverters system under two-phase rest frame Current on line side actual value i_sαAnd i_sβCarry out making difference process, and the result for making difference is input in ratio resonant regulator, ratio is humorous The actuator that shakes exports v_cαAnd v_cβ, ratio resonant regulator is exported v_cαAnd v_cβIt is input in First-order Integral actuator, further according to one Rank integral controller export voltage source inverter modulating wave initial order v_{ma0_ref}、v_{mb0_ref}And v_{mc0_ref}；

3) s domain transmission function G of active damping controller is set up_{ad_sx}(s), then the s domain of active damping controller is transmitted Function G_{ad_sx}S () carries out discretization, by step 1) current on line side of voltage source inverter under the two-phase rest frame that obtains Actual value i_sαAnd i_sβBy s domain transmission function G of the active damping controller of discretization_{ad_sx}S () is calculated, and will calculate As a result inverse Clark coordinate transform is carried out, obtains active damping control signal v_{ad_a}、v_{ad_b}And v_{ad_c}；

4) according to step 2) modulating wave initial order v of voltage source inverter that obtains_{ma0_ref}、v_{mb0_ref}And v_{mc0_ref} And step 3) active damping control signal v that obtains_{ad_a}、v_{ad_b}And v_{ad_c}The modulating wave command value of voltage source inverter is obtained, so According to the modulating wave command value of voltage source inverter, each switching device in voltage source inverter is controlled afterwards, completes Active damping control based on current on line side feedback.

Step 1) concrete operations be：

1.1) three-phase alternating current potential source type grid-connected inverters system point of common coupling voltage v is detected_sa、v_sbAnd v_sc, further according to Three-phase alternating current potential source type grid-connected inverters system point of common coupling voltage v_sa、v_sbAnd v_scCurrent electricity is obtained by phase-locked loop pll The angular frequency of net₀And phase theta；

1.2) according to the angular frequency of current electric grid₀And phase theta calculates three-phase alternating current potential source type grid-connected inverters system Three-phase current on line side command value i_{sa_ref}、i_{sb_ref}And i_{sc_ref}；

1.3) by step 1.2) the three-phase current on line side instruction of the three-phase alternating current potential source type grid-connected inverters system that obtains Value i_{sa_ref}、i_{sb_ref}And i_{sc_ref}Carry out three-phase static coordinate system to convert to the Clark of two-phase rest frame, obtain biphase static Current on line side command value i of three-phase alternating current potential source type grid-connected inverters system under coordinate system_{sα_ref}And i_{sβ_ref}；

1.4) the current on line side i of three-phase alternating current potential source type grid-connected inverters system is detected_sa、i_sbAnd i_sc, and three are intersected The current on line side i of stream voltage source inverter grid-connected system_sa、i_sbAnd i_scThree-phase static coordinate system is carried out to biphase static coordinate The Clark conversion of system, obtains the current on line side reality of three-phase alternating current potential source type grid-connected inverters system under two-phase rest frame Value i_sαAnd i_sβ.

Three-phase current on line side command value i of three-phase alternating current potential source type grid-connected inverters system_{sa_ref}、i_{sb_ref}And i_{sc_ref} Expression formula be：

Wherein, I_sa, I_sb, I_scThe amplitude that respectively three-phase current on line side is instructed.

Step 1.3) in three-phase static coordinate system to two-phase rest frame Clark convert transformation matrix T_abc-αβFor：

Step 2) concrete operations be：

2.1) by step 1) net of three-phase alternating current potential source type grid-connected inverters system under the two-phase rest frame that obtains Side current instruction value is i_{sα_ref}And i_{sβ_ref}Respectively with three-phase alternating current potential source type grid-connected inverters system under two-phase rest frame The current on line side actual value i of system_sαAnd i_sβCarry out making difference process, then the result for making difference process be input to ratio resonant regulator, Ratio resonant regulator exports v_cαAnd v_cβ；

2.2) by step 2.1) the ratio resonant regulator that obtains output v_cαAnd v_cβIt is separately input to First-order Integral actuator In, and the output result of First-order Integral actuator is carried out two-phase rest frame to the inverse Clark change of three-phase static coordinate system Change, obtain modulating wave initial order v of voltage source inverter_{ma0_ref}、v_{mb0_ref}And v_{mc0_ref}.

Step 2.2) in the calculating process of First-order Integral actuator be：

Wherein, K_sFor integral coefficient, T_sFor the sampling period of digitial controller, x (k) and y (k) respectively First-order Integral tune Section device is respectively First-order Integral actuator and adopts for -1 in kth in input and the output in k-th sampling period, x (k-1) and y (k-1) The input in sample cycle and output.

Step 2.2) in two-phase rest frame to three-phase static coordinate system inverse Clark convert transformation matrix T_αβ-abc For：

Step 3) concrete operations be：

3.1) resonance of LCL filter is obtained according to the circuit electrical parameter of three-phase alternating current potential source type grid-connected inverters system Angular frequency_res, wherein,

Wherein, L₁、L₂And C_fRespectively the inverter side inductance value of LCL filter, net side inductance value and filtering capacitance；

3.2) s domain transmission function G of active damping controller is built_{ad_sx}(s), wherein,

Wherein, ω_cFor corner frequency, ω_c=3 ω_res, ζ is damped coefficient, ζ=10⁴, R_vFor virtual equivalent resistance：

3.3) by s domain transmission function G of active damping controller_{ad_sx}S () carries out discretization, obtain the active resistance of discretization S domain transmission function G of Buddhist nun's controller_{ad_sx}S the way of realization of () in digitial controller is：

y₂(k)=R_v·x₁(k)

y₁(k)=y₂(k)+y₃(k)

Wherein, x₁(k) and y₁K () is respectively input and output of the active damping controller k-th sampling period, y₂(k) And y₃K () is respectively the intermediate variable in k-th sampling period；x₁And y (k-1)₃(k-1) active damping controller is respectively the The input quantity in k-1 sampling period and intermediate variable, x₁And y (k-2)₃(k-2) active damping controller is respectively in kth -2 The input quantity in sampling period and intermediate variable；

3.4) by step 1) net of three-phase alternating current potential source type grid-connected inverters system under the two-phase rest frame that obtains Side current actual value i_sαAnd i_sβIt is input in digitial controller, and by the active damping control of discretization in digitial controller S domain transmission function G of device processed_{ad_sx}S () is calculated, and the result of calculating is carried out two-phase rest frame to three phase static seat The inverse Clark conversion of mark system, obtains active damping control signal v_{ad_a}、v_{ad_b}And v_{ad_c}.

Step 4) concrete operations be：

4.1) by step 1) modulating wave initial order v of voltage source inverter that obtains_{ma0_ref}、v_{mb0_ref}And v_{mc0_ref} It is individually subtracted step 3) active damping control signal v that obtains_{ad_a}、v_{ad_b}And v_{ad_c}, result of calculation is respectively v_{ma_ref}、v_{mb_ref} And v_{mc_ref}, then by v_{ma_ref}、v_{mb_ref}And v_{mc_ref}Modulating wave command value as voltage source inverter；

4.2) by step 4.1) the modulating wave command value of voltage source inverter that obtains carries out SPWM modulation, must modulate letter Number, and realize amplified for the modulated signal drive signal as voltage source inverter breaker in middle device to voltage The control of each switching device in the type inverter of source, completes the active damping control based on current on line side feedback.

The invention has the advantages that：

Active damping control method based on current on line side feedback of the present invention detects three-phase in concrete operations, first Alternating-current voltage source type grid-connected inverters system point of common coupling voltage and current on line side command value, then passing ratio resonant regulator And First-order Integral actuator obtains the modulating wave initial order of voltage source inverter, wherein, have by First-order Integral actuator The dynamic characteristic of effect improvement system, resettles the s domain transmission function of active damping controller, and is obtained according to current on line side feedback Active damping control signal, recycles active damping control signal and the modulating wave initial order signal of voltage source inverter to obtain To the drive signal of corresponding switching device, the suppression to LCL resonance is realized, so that three-phase alternating current potential source type grid-connected inverters System normal table works.It should be noted that three-phase alternating current potential source type grid-connected inverters system point of common coupling voltage and The detection of current on line side command value can be realized by original sensor in system, and therefore cost is relatively low.

Description of the drawings

Fig. 1 is the grid-connected voltage source type inverter system main circuit schematic diagram for accessing electrical network by LCL filter；

Fig. 2 is combining inverter traditional single phase current on line side control block diagram；

Fig. 3 is the current on line side control block diagram for adding the active damping based on current on line side feedback；

Fig. 4 is a phase line voltage during no any damping and three-phase current on line side simulation waveform；

Fig. 5 be using a phase line voltage after the present invention and three-phase current on line side simulation waveform；

Fig. 6 is to be added without a phase line voltage and three-phase current on line side dynamic response during First-order Integral link in the present invention to imitate True oscillogram；

Fig. 7 is to add First-order Integral link a phase line voltage and three-phase current on line side Dynamic Response Simulation ripple in the present invention Shape figure.

Specific embodiment

Below in conjunction with the accompanying drawings the present invention is described in further detail：

Active damping control method based on current on line side feedback of the present invention is comprised the following steps：

1) three-phase alternating current potential source type grid-connected inverters system point of common coupling voltage v is detected_sa、v_sbAnd v_sc, according to three-phase Alternating-current voltage source type grid-connected inverters system point of common coupling voltage v_sa、v_sbAnd v_scCalculate net side electricity under two-phase rest frame Stream command value i_{sα_ref}And i_{sβ_ref}；The current on line side i of three-phase alternating current potential source type grid-connected inverters system is detected again_sa、i_sbAnd i_sc, further according to the current on line side i of three-phase alternating current potential source type grid-connected inverters system_sa、i_sbAnd i_scCalculate two-phase rest frame The current on line side actual value i of lower three-phase alternating current potential source type grid-connected inverters system_sαAnd i_sβ；

2) by step 1) net side of three-phase alternating current potential source type grid-connected inverters system under the two-phase rest frame that obtains Current instruction value i_{sα_ref}And i_{sβ_ref}Respectively with three-phase alternating current potential source type grid-connected inverters system under two-phase rest frame Current on line side actual value i_sαAnd i_sβCarry out making difference process, and the result for making difference is input in ratio resonant regulator, ratio is humorous The actuator that shakes exports v_cαAnd v_cβ, ratio resonant regulator is exported v_cαAnd v_cβIt is input in First-order Integral actuator, further according to one Rank integral controller export voltage source inverter modulating wave initial order v_{ma0_ref}、v_{mb0_ref}And v_{mc0_ref}；

3) s domain transmission function G of active damping controller is set up_{ad_sx}(s), then the s domain of active damping controller is transmitted Function G_{ad_sx}S () carries out discretization, by step 1) current on line side of voltage source inverter under the two-phase rest frame that obtains Actual value i_sαAnd i_sβBy s domain transmission function G of the active damping controller of discretization_{ad_sx}S () is calculated, and will calculate As a result inverse Clark coordinate transform is carried out, obtains active damping control signal v_{ad_a}、v_{ad_b}And v_{ad_c}；

4) according to step 2) modulating wave initial order v of voltage source inverter that obtains_{ma0_ref}、v_{mb0_ref}And v_{mc0_ref} And step 3) active damping control signal v that obtains_{ad_a}、v_{ad_b}And v_{ad_c}The modulating wave command value of voltage source inverter is obtained, so According to the modulating wave command value of voltage source inverter, each switching device in voltage source inverter is controlled afterwards, completes Active damping control based on current on line side feedback.

Step 1) concrete operations be：

1.1) three-phase alternating current potential source type grid-connected inverters system point of common coupling voltage v is detected_sa、v_sbAnd v_sc, further according to Three-phase alternating current potential source type grid-connected inverters system point of common coupling voltage v_sa、v_sbAnd v_scCurrent electricity is obtained by phase-locked loop pll The angular frequency of net₀And phase theta；

1.2) according to the angular frequency of current electric grid₀And phase theta calculates three-phase alternating current potential source type grid-connected inverters system Three-phase current on line side command value i_{sa_ref}、i_{sb_ref}And i_{sc_ref}；

1.3) by step 1.2) the three-phase current on line side instruction of the three-phase alternating current potential source type grid-connected inverters system that obtains Value i_{sa_ref}、i_{sb_ref}And i_{sc_ref}Carry out three-phase static coordinate system to convert to the Clark of two-phase rest frame, obtain biphase static Current on line side command value i of three-phase alternating current potential source type grid-connected inverters system under coordinate system_{sα_ref}And i_{sβ_ref}；

1.4) the current on line side i of three-phase alternating current potential source type grid-connected inverters system is detected_sa、i_sbAnd i_sc, and three are intersected The current on line side i of stream voltage source inverter grid-connected system_sa、i_sbAnd i_scThree-phase static coordinate system is carried out to biphase static coordinate The Clark conversion of system, obtains the current on line side reality of three-phase alternating current potential source type grid-connected inverters system under two-phase rest frame Value i_sαAnd i_sβ.

Wherein, three-phase current on line side command value i of three-phase alternating current potential source type grid-connected inverters system_{sa_ref}、i_{sb_ref}And i_{sc_ref}Expression formula be：

Wherein, I_sa, I_sb, I_scThe amplitude that respectively three-phase current on line side is instructed.

Step 1.3) in three-phase static coordinate system to two-phase rest frame Clark convert transformation matrix T_abc-αβFor：

Step 2) concrete operations be：

2.1) by step 1) net of three-phase alternating current potential source type grid-connected inverters system under the two-phase rest frame that obtains Side current instruction value is i_{sα_ref}And i_{sβ_ref}Respectively with three-phase alternating current potential source type grid-connected inverters system under two-phase rest frame The current on line side actual value i of system_sαAnd i_sβCarry out making difference process, then the result for making difference process be input to ratio resonant regulator, Ratio resonant regulator exports v_cαAnd v_cβ；

2.2) by step 2.1) the ratio resonant regulator that obtains output v_cαAnd v_cβIt is separately input to First-order Integral actuator In, and the output result of First-order Integral actuator is carried out two-phase rest frame to the inverse Clark change of three-phase static coordinate system Change, obtain modulating wave initial order v of voltage source inverter_{ma0_ref}、v_{mb0_ref}And v_{mc0_ref}.

Step 2.2) in the calculating process of First-order Integral actuator be：

Wherein, K_sFor integral coefficient, T_sFor the sampling period of digitial controller, x (k) and y (k) respectively integral controller In input and the output in k-th sampling period, x (k-1) and y (k-1) is respectively First-order Integral actuator in -1 sampling week of kth The input of phase and output.

Step 2.2) in two-phase rest frame to three-phase static coordinate system inverse Clark convert transformation matrix T_αβ-abc For：

Step 3) concrete operations be：

3.1) resonance of LCL filter is obtained according to the circuit electrical parameter of three-phase alternating current potential source type grid-connected inverters system Angular frequency_res, wherein,

Wherein, L₁、L₂And C_fRespectively the inverter side inductance value of LCL filter, net side inductance value and filtering capacitance；

3.2) s domain transmission function G of active damping controller is built_{ad_sx}(s), wherein,

Wherein, ω_cFor corner frequency, ω_c=3 ω_res, ζ is damped coefficient, ζ=10⁴, R_vFor virtual equivalent resistance：

3.3) by s domain transmission function G of active damping controller_{ad_sx}S () carries out discretization, obtain the active resistance of discretization S domain transmission function G of Buddhist nun's controller_{ad_sx}S the way of realization of () in digitial controller is：

y₂(k)=R_v·x₁(k)

y₁(k)=y₂(k)+y₃(k)

Wherein, x₁(k) and y₁K () is respectively input and output of the active damping controller k-th sampling period, y₂(k) And y₃K () is respectively the intermediate variable in k-th sampling period；x₁And y (k-1)₃(k-1) active damping controller is respectively the The input quantity in k-1 sampling period and intermediate variable, x₁And y (k-2)₃(k-2) active damping controller is respectively in kth -2 The input quantity in sampling period and intermediate variable；

3.4) by step 1) net of three-phase alternating current potential source type grid-connected inverters system under the two-phase rest frame that obtains Side current actual value i_sαAnd i_sβIt is input in digitial controller, and by the active damping control of discretization in digitial controller S domain transmission function G of device processed_{ad_sx}S () is calculated, and the result of calculating is carried out two-phase rest frame to three phase static seat The inverse Clark conversion of mark system, obtains active damping control signal v_{ad_a}、v_{ad_b}And v_{ad_c}.

Step 4) concrete operations be：

4.1) by step 1) modulating wave initial order v of voltage source inverter that obtains_{ma0_ref}、v_{mb0_ref}And v_{mc0_ref} It is individually subtracted step 3) active damping control signal v that obtains_{ad_a}、v_{ad_b}And v_{ad_c}, result of calculation is respectively v_{ma_ref}、v_{mb_ref} And v_{mc_ref}, then by v_{ma_ref}、v_{mb_ref}And v_{mc_ref}Modulating wave command value as voltage source inverter；

4.2) by step 4.1) the modulating wave command value of voltage source inverter that obtains carries out SPWM modulation, must modulate letter Number, and realize amplified for the modulated signal drive signal as voltage source inverter breaker in middle device to voltage The control of each switching device in the type inverter of source, completes the active damping control based on current on line side feedback.

Contrast Fig. 4 and Fig. 5 understands, in the case of any damping is not added with, voltage source inverter operates in labile state； After adding the present invention, voltage source inverter can be contrasted Fig. 6 and Fig. 7 and understood with stable operation, and introducing First-order Integral device can be big Improve greatly system dynamics response characteristic；From fig. 6, it can be seen that after current on line side instruction occurs Spline smoothing, whole system needs About 8 power frequency periods can just enter stable state；After First-order Integral device is added, whole system is entered by only needing about half power frequency period Enter stable state.

Claims (9)

1. a kind of active damping control method based on current on line side feedback, it is characterised in that comprise the following steps：

1) three-phase alternating current potential source type grid-connected inverters system point of common coupling voltage v is detected_sa、v_sbAnd v_sc, according to three-phase alternating current Voltage source inverter grid-connected system point of common coupling voltage v_sa、v_sbAnd v_scCalculate current on line side under two-phase rest frame to refer to Make value i_{sα_ref}And i_{sβ_ref}；The current on line side i of three-phase alternating current potential source type grid-connected inverters system is detected again_sa、i_sbAnd i_sc, then Current on line side i according to three-phase alternating current potential source type grid-connected inverters system_sa、i_sbAnd i_scCalculate three under two-phase rest frame The current on line side actual value i of cross streams voltage source inverter grid-connected system_sαAnd i_sβ；

2) by step 1) current on line side of three-phase alternating current potential source type grid-connected inverters system under the two-phase rest frame that obtains Command value i_{sα_ref}And i_{sβ_ref}Net side with three-phase alternating current potential source type grid-connected inverters system under two-phase rest frame respectively Current actual value i_sαAnd i_sβCarry out making difference process, and the result for making difference is input in ratio resonant regulator, ratio resonance is adjusted Section device output v_cαAnd v_cβ, ratio resonant regulator is exported v_cαAnd v_cβIt is input in First-order Integral actuator, accumulates further according to single order Point actuator export voltage source inverter modulating wave initial order v_{ma0_ref}、v_{mb0_ref}And v_{mc0_ref}；

3) s domain transmission function G of active damping controller is set up_{ad_sx}(s), then the s domain transmission function to active damping controller G_{ad_sx}S () carries out discretization, by step 1) the current on line side reality of voltage source inverter under the two-phase rest frame that obtains Value i_sαAnd i_sβBy s domain transmission function G of the active damping controller of discretization_{ad_sx}S () is calculated, and by result of calculation Inverse Clark coordinate transform is carried out, obtains active damping control signal v_{ad_a}、v_{ad_b}And v_{ad_c}；

4) according to step 2) modulating wave initial order v of voltage source inverter that obtains_{ma0_ref}、v_{mb0_ref}And v_{mc0_ref}And step Active damping control signal v that rapid 3) obtain_{ad_a}、v_{ad_b}And v_{ad_c}Obtain the modulating wave command value of voltage source inverter, Ran Hougen According to the modulating wave command value of voltage source inverter, each switching device in voltage source inverter is controlled, completes to be based on The active damping control of current on line side feedback.

2. the active damping control method based on current on line side feedback according to claim 1, it is characterised in that step 1) Concrete operations be：

1.1) three-phase alternating current potential source type grid-connected inverters system point of common coupling voltage v is detected_sa、v_sbAnd v_sc, further according to three-phase Alternating-current voltage source type grid-connected inverters system point of common coupling voltage v_sa、v_sbAnd v_scCurrent electric grid is obtained by phase-locked loop pll Angular frequency₀And phase theta；

1.2) according to the angular frequency of current electric grid₀And phase theta calculates the three-phase of three-phase alternating current potential source type grid-connected inverters system Current on line side command value i_{sa_ref}、i_{sb_ref}And i_{sc_ref}；

1.3) by step 1.2) the three-phase current on line side command value of three-phase alternating current potential source type grid-connected inverters system that obtains i_{sa_ref}、i_{sb_ref}And i_{sc_ref}Carry out three-phase static coordinate system to convert to the Clark of two-phase rest frame, obtain biphase static seat Current on line side command value i of the lower three-phase alternating current potential source type grid-connected inverters system of mark system_{sα_ref}And i_{sβ_ref}；

1.4) the current on line side i of three-phase alternating current potential source type grid-connected inverters system is detected_sa、i_sbAnd i_sc, and by three-phase alternating current The current on line side i of potential source type grid-connected inverters system_sa、i_sbAnd i_scThree-phase static coordinate system is carried out to two-phase rest frame Clark is converted, and obtains the current on line side actual value i of three-phase alternating current potential source type grid-connected inverters system under two-phase rest frame_sα And i_sβ.

3. the active damping control method based on current on line side feedback according to claim 2, it is characterised in that three intersect Three-phase current on line side command value i of stream voltage source inverter grid-connected system_{sa_ref}、i_{sb_ref}And i_{sc_ref}Expression formula be：

$\left\{\begin{array}{c}{i}_{sa\_ref}=I_{sa}sin\mathrm{\θ}\\ i_{sb\_ref}=I_{sb}sin(\mathrm{\θ}-2\mathrm{\π}/3)\\ i_{sc\_ref}=I_{sc}sin(\mathrm{\θ}+2\mathrm{\π}/3)\end{array}\right.$

Wherein, I_sa, I_sb, I_scThe amplitude that respectively three-phase current on line side is instructed.

4. the active damping control method based on current on line side feedback according to claim 2, it is characterised in that step 1.3) the transformation matrix T that in, three-phase static coordinate system is converted to the Clark of two-phase rest frame_abc-αβFor：

$T_{abc-\mathrm{\α}\mathrm{\β}}=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right].$

5. the active damping control method based on current on line side feedback according to claim 1, it is characterised in that step 2) Concrete operations be：

2.1) by step 1) the net side electricity of three-phase alternating current potential source type grid-connected inverters system under the two-phase rest frame that obtains Stream command value is i_{sα_ref}And i_{sβ_ref}Respectively with three-phase alternating current potential source type grid-connected inverters system under two-phase rest frame Current on line side actual value i_sαAnd i_sβCarry out making difference process, then the result for making difference process is input to ratio resonant regulator, ratio Resonant regulator exports v_cαAnd v_cβ；

2.2) by step 2.1) the ratio resonant regulator that obtains output v_cαAnd v_cβIt is separately input in First-order Integral actuator, and The output result of First-order Integral actuator is carried out two-phase rest frame convert to the inverse Clark of three-phase static coordinate system, obtain Modulating wave initial order v of voltage source inverter_{ma0_ref}、v_{mb0_ref}And v_{mc0_ref}.

6. the active damping control method based on current on line side feedback according to claim 5, it is characterised in that step 2.2) in, the calculating process of First-order Integral actuator is：

$y\left(k\right)=\frac{K_s{T}_s}{2}\[x\left(k\right)+x(k-1)\]+y(k-1)$

Wherein, K_sFor integral coefficient, T_sFor the sampling period of digitial controller, x (k) and y (k) respectively First-order Integral actuator In input and the output in k-th sampling period, x (k-1) and y (k-1) is respectively First-order Integral actuator in -1 sampling week of kth The input of phase and output.

7. the active damping control method based on current on line side feedback according to claim 5, it is characterised in that step 2.2) the transformation matrix T that in, two-phase rest frame is converted to the inverse Clark of three-phase static coordinate system_αβ-abcFor：

$T_{\mathrm{\α}\mathrm{\β}-abc}=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& 0& \frac{1}{\sqrt{2}}\\ -\frac{1}{2}& \frac{\sqrt{3}}{2}& \frac{1}{\sqrt{2}}\\ -\frac{1}{2}& -\frac{\sqrt{3}}{2}& \frac{1}{\sqrt{2}}\end{array}\right].$

8. the active damping control method based on current on line side feedback according to claim 1, it is characterised in that step 3) Concrete operations be：

3.1) the resonance angular frequency of LCL filter is obtained according to the circuit electrical parameter of three-phase alternating current potential source type grid-connected inverters system Rate ω_res, wherein,

${\mathrm{\ω}}_{res}=\sqrt{\frac{L_1+L_2}{L_1{L}_2{C}_f}}$

Wherein, L₁、L₂And C_fRespectively the inverter side inductance value of LCL filter, net side inductance value and filtering capacitance；

3.2) s domain transmission function G of active damping controller is built_{ad_sx}(s), wherein,

$G_{ad\_sx}\left(s\right)=(1+L_1{C}_f\·\frac{{\mathrm{\ω}}_c^2\·s^2}{s^2+\mathrm{\ζ}s+{\mathrm{\ω}}_c^2})\·R_v$

Wherein, ω_cFor corner frequency, ω_c=3 ω_res, ζ is damped coefficient, ζ=10⁴, R_vFor virtual equivalent resistance：

3.3) by s domain transmission function G of active damping controller_{ad_sx}S () carries out discretization, obtain the active damping control of discretization S domain transmission function G of device processed_{ad_sx}S the way of realization of () in digitial controller is：

y₂(k)=R_v·x₁(k)

$\begin{array}{c}(1+\frac{{\mathrm{\ζT}}_s}{2}+\frac{T_s^2{\mathrm{\ω}}_c^2}{4})\·y_3\left(k\right)=R_v{L}_1{C}_f{\mathrm{\ω}}_c^2\[x_1\left(k\right)-2x_1(k-1)+x_1(k-2)\]\\ +(2-\frac{T_s^2{\mathrm{\ω}}_c^2}{2})y_3(k-1)+(\frac{{\mathrm{\ζT}}_s}{2}-1-\frac{T_s^2{\mathrm{\ω}}_c^2}{4})y_3(k-2)\end{array}$

y₁(k)=y₂(k)+y₃(k)

Wherein, x₁(k) and y₁K () is respectively input and output of the active damping controller k-th sampling period, y₂(k) and y₃ K () is respectively the intermediate variable in k-th sampling period；x₁And y (k-1)₃(k-1) active damping controller is respectively in kth -1 The input quantity in sampling period and intermediate variable, x₁And y (k-2)₃(k-2) active damping controller is respectively in -2 sampling weeks of kth The input quantity of phase and intermediate variable；

3.4) by step 1) the net side electricity of three-phase alternating current potential source type grid-connected inverters system under the two-phase rest frame that obtains Stream actual value i_sαAnd i_sβIt is input in digitial controller, and by the active damping controller of discretization in digitial controller S domain transmission function G_{ad_sx}S () is calculated, and the result of calculating is carried out two-phase rest frame to three-phase static coordinate system Inverse Clark conversion, obtain active damping control signal v_{ad_a}、v_{ad_b}And v_{ad_c}.

9. the active damping control method based on current on line side feedback according to claim 1, it is characterised in that step 4) Concrete operations be：

4.1) by step 1) modulating wave initial order v of voltage source inverter that obtains_{ma0_ref}、v_{mb0_ref}And v_{mc0_ref}Respectively Deduct step 3) active damping control signal v that obtains_{ad_a}、v_{ad_b}And v_{ad_c}, result of calculation is respectively v_{ma_ref}、v_{mb_ref}And v_{mc_ref}, then by v_{ma_ref}、v_{mb_ref}And v_{mc_ref}Modulating wave command value as voltage source inverter；

4.2) by step 4.1) the modulating wave command value of voltage source inverter that obtains carries out SPWM modulation, obtains modulated signal, And realize amplified for the modulated signal drive signal as voltage source inverter breaker in middle device to voltage-source type The control of each switching device in inverter, completes the active damping control based on current on line side feedback.