CN103401242B - A kind of control method of multi-inverter system resonance restraining device - Google Patents

Abstract

The invention discloses a kind of multi-inverter system resonance restraining device and control method.Described multi-inverter system resonance restraining device is connected to the points of common connection (PCC) of multiple inverter system.Described multi-inverter system resonance restraining device only needs to sample to PCC voltage, does not need sampling PCC current signal, does not need each inverter software and hardware configuration in amendment multiple inverter system; The control method of described multi-inverter system resonance restraining device, general principle is by multi-inverter system resonance restraining device is invented the resistance that one works in all resonance frequency sections, suppress the resonance phenomena of multiple inverter system, simply effectively, feasibility.

Description

A kind of control method of multi-inverter system resonance restraining device

Technical field

The present invention relates to field of new energy generation, be specifically related to a kind of for suppressing multiple new forms of energy interface inverter parallel system resonance time the control method of resonance restraining device.

Background technology

Along with the generation of electricity by new energy industry for solar power system increases rapidly, the application of new forms of energy interface inverter is more and more extensive, and application scale is increasing, and inverter number in parallel in same grid-connected power generation system increases gradually.But the multiple inverter system stability formed can increase along with the inverter number of parallel connection and decline, and especially with the inverter of LCL output filter, very easily causes the resonance of multiple inverter system.Multi-inverter system resonance problem has made the reliable and stable operation of electricity generation system and electrical network receive severe challenge.

For the combining inverter with LCL filter, in order to effectively suppress inverter resonance, general employing active damping strategy, namely increases inverter damping by control algolithm and suppresses resonance.But, along with increasing of shunt chopper number, the resonance of multiple inverter system may not be suppressed well for the effective active damping algorithm of single inverter.In addition, for the multiple inverter system built up, change control algolithm, the change of software even on hardware can be related to, cause the program usually cannot realize, poor feasibility.

Summary of the invention

In order under the condition not changing each inverter software and hardware configuration of multiple inverter system, solve multi-inverter system resonance problem, the invention provides a kind of control method of multi-inverter system resonance restraining device.The multi-inverter system resonance restraining device provided works in points of common connection and the PCC place of multiple inverter system, and only needing to obtain PCC place voltage signal does not need current signal, is easy to gather; The multi-inverter system resonance restraining device provided comprises voltage source inverter and control system thereof, and its control cincture is wider than the highest resonance frequency of multiple inverter system.

To achieve these goals, the technical solution used in the present invention is as follows:

A control method for multi-inverter system resonance restraining device, wherein multi-inverter system resonance restraining device comprises voltage source inverter (10) and control system (20) thereof,

Described voltage source inverter (10) comprises DC side (101), power switch pipe (102), LCL output filter (103); The output of described DC side (101) is connected with the input of power switch pipe (102), and the output of described power switch pipe (102) is connected with the input of LCL output filter (103);

Described control system (20) comprises sampling unit (201), harmonic extraction unit (202), instruction current computing unit (203) and current follow-up control unit (204), the voltage signal output end of described sampling unit (201) is connected with the input of harmonic extraction unit (202), the input of the output and instruction current calculation unit (203) of described harmonic extraction unit (202) is connected, gained difference input current tracing control unit (204) after the sampled output current that the current signal output end that the instruction output current that described instruction current computing unit (203) sends deducts described sampling unit (201) sends, described current follow-up control unit (204) calculates PWM switching drive signal and sends to the DC side (101) of voltage source inverter (10), the PWM switching drive signal that DC side (101) received current tracing control unit (204) of described voltage source inverter (10) sends, control described power switch pipe (102) and produce the output current expected,

Points of common connection (PCC) place that in described voltage source inverter (10), output access multi-inverter group (30) of LCL output filter (103) is connected with electrical network (40); Voltage sensor (the H of sampling unit (201) in described control system (20) _v) be arranged on the grid side of points of common connection (PCC), the current sensor (H of sampling unit (201) in described control system (20) _i) be arranged on the side that points of common connection (PCC) is connected with described voltage source inverter (10);

It is characterized in that: by described multi-inverter system resonance restraining device is invented the resistance that one works in all resonance frequency sections, realize the object suppressing multi-inverter system resonance phenomenon, this control method specifically comprises the following steps:

Step one: utilize the voltage sensor (H in sampling unit (201) _v) detect points of common connection (PCC) voltage U _pcc; Utilize the current sensor (H in sampling unit (201) _i) detect sampled output current I _out, described sampling unit (201) will detect points of common connection (PCC) voltage U obtained _pccbe sent to described harmonic extraction unit (202);

Step 2: points of common connection (PCC) voltage U that described harmonic extraction unit (202) detects according to step one _pcc, extract points of common connection (PCC) voltage U _pccin harmonic component U _h, described harmonic extraction unit (202) is by harmonic component U _hbe sent to instruction current computing unit (203), described instruction current computing unit (203) and according to setting virtual resistance value R _h, the instruction output current I utilizing formula (1) to calculate instruction current computing unit (203) to send _ref;

$I_{\mathrm{ref}}=\frac{U_h}{R_h}---\left(1\right)$

Step 3: the instruction output current I obtained according to step 2 _refand the sampled output current I that step one detects _out, utilize formula (2) to calculate current error signal e;

e＝I _ref‐I _out(2)

Step 4: the current error signal e that described current follow-up control unit (204) obtains according to step 3, carry out current follow-up control and generate obtaining PWM switching drive signal, described PWM switching drive signal controls described power switch pipe (102) and produces the output current expected.

The band of described current follow-up control is wider than the highest resonance frequency of multiple inverter system.

Described current follow-up control mode can control by usage ratio resonance, its controller transfer function G _pRs () is as shown in formula (3):

$G_{\mathrm{PR}}\left(s\right)=K_{P\_\mathrm{PR}}+\underset{i=\mathrm{1,5,7},\·\·\·}{\mathrm{\Σ}}\frac{K_{r\_i}\mathrm{i\ωs}}{s^2+{\left(\mathrm{i\ω}\right)}^2}---\left(3\right)$

Wherein: K _{p_PR}for proportionality coefficient, K _{r_i}for resonance coefficient, i is harmonic number, and ω is line voltage angular frequency, and s is Laplacian.

Described current follow-up control mode can also use P+VPI to control, its controller transfer function G _p+VPIs () is as shown in formula (4):

$G_{P+\mathrm{VPI}}\left(s\right)=K_P+\underset{i=\mathrm{1,6,12},\·\·\·}{\mathrm{\Σ}}\frac{K_{i}s(\mathrm{Ls}+R)}{s^2+{\left(\mathrm{i\ω}\right)}^2}---\left(4\right)$

In formula: K _pfor proportionality coefficient, K _ifor integral coefficient, i is harmonic number, and L is output filter total inductance, and R is the total dead resistance of output filter inductance, and ω is line voltage angular frequency, and s is Laplacian.

Advantage of the present invention: do not need the software and hardware configuration changing each inverter in multiple inverter system, be easy to realize, feasibility is high; Only need to sample to PCC voltage, do not need sampling PCC current signal, can the resonance phenomena of simple and effective suppression multiple inverter system.

Accompanying drawing explanation

The circuit of Fig. 1 multi-inverter system resonance restraining device and the structure principle chart of control method.

Fig. 2 adopts multi-inverter system resonance situation simulation result figure before and after the present invention.

Embodiment

Below in conjunction with accompanying drawing, with instantiation, embodiment of the present invention is described.

Figure 1 shows that the structure principle chart of the multi-inverter system resonance restraining device circuit that the present invention carries and control method.A kind of multi-inverter system resonance restraining device provided by the invention, comprise voltage source inverter 10 and control system 20 thereof, described voltage source inverter comprises DC side 101, power switch pipe 102, LCL output filter 103, described control system 20 comprises sampling unit 201, harmonic extraction unit 202, instruction current computing unit 203 and current follow-up control unit 204, voltage signal and current signal that control system 20 obtains according to sampling, calculate PWM switching drive signal and send to voltage source inverter 10, the PWM switching drive signal that voltage source inverter 10 sends according to receiving control system 20, control its power switch pipe 102, produce the output current of wishing, described multi-inverter system resonance restraining device accesses the points of common connection PCC be connected with electrical network 40 in multi-inverter group 30, and does not need each inverter software and hardware parameter in amendment multiple inverter system both can suppress multi-inverter system resonance.Wherein, the line voltage effective value of electrical network 40 is 315V, electrical network equivalent inductance L _gfor 0.032mH, the inverter number that multi-inverter group 30 comprises is 2, and every platform inverter rated power is 500KW, and the highest resonance frequency of multiple inverter system is 1.5KHz, and switching frequency is 3KHz.In order to ensure that the current follow-up control band of carried multi-inverter system resonance restraining device and control method is wider than the highest resonance frequency of multiple inverter system, the switching frequency of the power switch pipe 102 of multi-inverter system resonance restraining device elects 15KHz as, the resonance frequency of its LCL filter 103 is designed to 4Khz, design the controling parameters of its control system 20, make its current loop control bandwidth be 2KHz.

The control method of multi-inverter system resonance restraining device controls multi-inverter system resonance restraining device in accordance with the following steps:

Step one: utilize the voltage sensor H in sampling unit 201 _vdetect PCC voltage U _pcc; Utilize the current sensor H in sampling unit 201 _idetect the output current I of multi-inverter system resonance restraining device _out;

Step 2: the PCC voltage U detected according to step one _pcc, extract the harmonic component U in PCC voltage _h, and according to the virtual resistance value R set _h, utilize formula (1) to calculate the instruction output current I of multi-inverter system resonance restraining device _ref;

$I_{\mathrm{ref}}=\frac{U_h}{R_h}---\left(1\right)$

Wherein, virtual resistance R _hvalue, according to PCC voltage U _pccaberration rate and put forward the stability of multi-inverter system resonance restraining device, be set as 0.7 ohm.

Step 3: according to the instruction output current I of the multi-inverter system resonance restraining device that step 2 obtains _refand the output current I of multi-inverter system resonance restraining device that step one detects _out, utilize formula (2) to calculate current error signal e;

e＝I _ref‐I _out(2)

Step 4: the current error signal e obtained according to step 3, carries out current follow-up control and generates the pwm control signal obtaining multi-inverter system resonance restraining device switching tube, controls multi-inverter system resonance restraining device and exports the output current expected.

Current follow-up control wherein in step 4, can carry out current follow-up control by usage ratio resonance (PR) controller, PR controller transfer function G _pRs () is as shown in formula (3):

$G_{\mathrm{PR}}\left(s\right)=K_{P\_\mathrm{PR}}+\underset{i=\mathrm{1,5,7},\·\·\·}{\mathrm{\Σ}}\frac{K_{r\_i}\mathrm{i\ωs}}{s^2+{\left(\mathrm{i\ω}\right)}^2}---\left(3\right)$

In formula: K _{p_PR}for ratio resonant controller proportionality coefficient, K _{r_i}for resonance coefficient, i is harmonic number, and ω is line voltage angular frequency, be 100 π (rad/s), s is Laplacian.Current error e inputs PR controller, the output signal of PR controller, through SVPWM modulation, generate the pwm control signal obtaining the power switch pipe 102 controlling multi-inverter system resonance restraining device 10, and then control multi-inverter system resonance restraining device 10 exports the output current expected.Wherein, controller parameter is as following table:

K p	K r_1	K r_5	K r_7	K r_11	K r_13	K r_17	K r_19	K r_23	K r_25	K r_29	K r_31	K r_35	K r_37
														5	50	10	10	10	6	6	4	4	4	2	1	1	1

In addition, the current follow-up control in step 4 can also use P+VPI to control, its controller transfer function G _p+VPIs () is as shown in formula (4):

$G_{P+\mathrm{VPI}}\left(s\right)=K_P+\underset{i=\mathrm{1,6,12},\·\·\·}{\mathrm{\Σ}}\frac{K_{i}s(\mathrm{Ls}+R)}{s^2+{\left(\mathrm{i\ω}\right)}^2}---\left(4\right)$

In formula: K _pfor proportionality coefficient, K _ifor integral coefficient, i is harmonic number, and L is output filter total inductance, be 0.36 (mH), R being the total dead resistance of output filter inductance, is 0.0057 (Ω), ω is line voltage angular frequency, be 100 π (rad/s), s is Laplacian.Current error e is after Synchronous Reference Frame Transform, input P+VPI controls controller, the output signal of P+VPI controller, SVPWM modulation is carried out after synchronous inverse transformation, generate the pwm control signal obtaining the power switch pipe 102 controlling multi-inverter system resonance restraining device 10, and then control the output current that multi-inverter system resonance restraining device 10 exports expectation.Wherein, controller parameter is as following table:

K p	K 1	K 6	K 12	K 18	K 24	K 30	K 36
								4	5	0.1131	0.0565	0.0565	0.0565	0.0057	0.0057

Fig. 2 is for adopting multi-inverter system resonance situation simulation result figure before and after the present invention.Wherein IEgabc is power network current, and IL2_inv1 is First inverter output current, and IL2_inv2 is second inverter output current, and IL2_Global is multi-inverter system resonance restraining device output current.As shown in Figure 2, during T=0.1, First inverter puts into operation, and during T=0.15, second inverter puts into operation, and during T=0.2, multi-inverter system resonance restraining device puts into operation, and during T=0.26, full multi-inverter system resonance restraining device is out of service.As seen from the figure, the multi-inverter system resonance restraining device that the present invention carries and method thereof, effectively can suppress the resonance phenomena of multiple inverter system.Meanwhile, the multi-inverter system resonance restraining device carried and method thereof, only need PCC voltage sample, do not need the software and hardware configuration of each inverter in sampling PCC current signal or change multiple inverter system.Therefore, the multi-inverter system resonance restraining device that the present invention carries and method thereof have effectively simple, the advantage that feasibility is high.

Claims (4)

1. a control method for multi-inverter system resonance restraining device, wherein multi-inverter system resonance restraining device comprises voltage source inverter (10) and control system (20) thereof,

Described voltage source inverter (10) comprises DC side (101), power switch pipe (102), LCL output filter (103); The output of described DC side (101) is connected with the input of power switch pipe (102), and the output of described power switch pipe (102) is connected with the input of LCL output filter (103);

Described control system (20) comprises sampling unit (201), harmonic extraction unit (202), instruction current computing unit (203) and current follow-up control unit (204), the voltage signal output end of described sampling unit (201) is connected with the input of harmonic extraction unit (202), the input of the output and instruction current calculation unit (203) of described harmonic extraction unit (202) is connected, gained difference input current tracing control unit (204) after the sampled output current that the current signal output end that the instruction output current that described instruction current computing unit (203) sends deducts described sampling unit (201) sends, described current follow-up control unit (204) calculates PWM switching drive signal and sends to the DC side (101) of voltage source inverter (10), the PWM switching drive signal that DC side (101) received current tracing control unit (204) of described voltage source inverter (10) sends, control described power switch pipe (102) and produce the output current expected,

Points of common connection (PCC) place that in described voltage source inverter (10), output access multi-inverter group (30) of LCL output filter (103) is connected with electrical network (40); Voltage sensor (the H of sampling unit (201) in described control system (20) _v) be arranged on the grid side of points of common connection (PCC), the current sensor (H of sampling unit (201) in described control system (20) _i) be arranged on the side that points of common connection (PCC) is connected with described voltage source inverter (10);

It is characterized in that: by described multi-inverter system resonance restraining device is invented the resistance that one works in all resonance frequency sections, realize the object suppressing multi-inverter system resonance phenomenon, this control method specifically comprises the following steps:

Step one: utilize the voltage sensor (H in sampling unit (201) _v) detect points of common connection (PCC) voltage U _pcc; Utilize the current sensor (H in sampling unit (201) _i) detect sampled output current I _out, described sampling unit (201) will detect points of common connection (PCC) voltage U obtained _pccbe sent to described harmonic extraction unit (202);

Step 2: points of common connection (PCC) voltage U that described harmonic extraction unit (202) detects according to step one _pcc, extract points of common connection (PCC) voltage U _pccin harmonic component U _h, described harmonic extraction unit (202) is by harmonic component U _hbe sent to instruction current computing unit (203), described instruction current computing unit (203) and according to setting virtual resistance value R _h, the instruction output current I utilizing formula (1) to calculate instruction current computing unit (203) to send _ref;

$I_{\mathrm{ref}}=\frac{U_h}{R_h}---\left(1\right)$

Step 3: the instruction output current I obtained according to step 2 _refand the sampled output current I that step one detects _out, utilize formula (2) to calculate current error signal e;

e＝I _ref‐I _out(2)

Step 4: the current error signal e that described current follow-up control unit (204) obtains according to step 3, carry out current follow-up control and generate obtaining PWM switching drive signal, described PWM switching drive signal controls described power switch pipe (102) and produces the output current expected.

2. the control method of a kind of multi-inverter system resonance restraining device according to claim 1, is characterized in that: the band of the current follow-up control described in step 4 is wider than the highest resonance frequency of multiple inverter system.

3. the control method of a kind of multi-inverter system resonance restraining device according to claim 1, is characterized in that: the current follow-up control mode described in step 4 is that ratio resonance controls, its controller transfer function G _pRs () is as shown in formula (3):

$G_{\mathrm{PR}}\left(s\right)=K_{P\_\mathrm{PR}}+\underset{i=\mathrm{1,5,7},...}{\mathrm{\Σ}}\frac{K_{r\_i}\mathrm{i\ωs}}{s^2+{\left(\mathrm{i\ω}\right)}^2}---\left(3\right)$

Wherein: K _{p_PR}for proportionality coefficient, K _{r_i}for resonance coefficient, i is harmonic number, and ω is line voltage angular frequency, and s is Laplacian.

4. the control method of a kind of multi-inverter system resonance restraining device according to claim 1, is characterized in that: the current follow-up control mode described in step 4 is that P+VPI controls, its controller transfer function G _p+VPIs () is as shown in formula (4):

$G_{P+\mathrm{VPI}}\left(s\right)=K_p+\underset{i=\mathrm{1,6,12},...}{\mathrm{\Σ}}\frac{K_{i}s(\mathrm{Ls}+R)}{s^2+{\left(\mathrm{i\ω}\right)}^2}---\left(4\right)$

Wherein: K _pfor proportionality coefficient, K _ifor integral coefficient, i is harmonic number, and L is output filter total inductance, and R is the total dead resistance of output filter inductance, and ω is line voltage angular frequency, and s is Laplacian.