CN104811021A - Inverter voltage control method for inhibiting voltage harmonic - Google Patents

Abstract

The invention discloses an inverter voltage control method for inhibiting voltage harmonic. The method specifically comprises the steps of acquiring inverter filter capacitive voltage Ux; subtracting voltage reference value Urefx from the inverter filter capacitive voltage Ux to obtain voltage error value delta Ux; regulating the voltage error value delta Ux through an improved proportional complex integral controller to obtain current reference value irefx; subtracting the current reference value irefx from the capacitive current iCx to obtain current error delta ix; regulating the current error delta ix through a current regulator to generate a modulating signal; generating a switch control signal through a modulating module according to the modulating signal so as to control an inverter. The method can solve the problem of distortion of total voltage harmonic due to voltage distortion under nonlinear load in the prior art.

Description

A kind of contravarianter voltage control method suppressing voltage harmonic

Technical field

The invention belongs to micro-capacitance sensor from distributed power source technical field of power generation under net pattern, relate to a kind of contravarianter voltage control method suppressing voltage harmonic.

Background technology

Along with the development of science and technology, produce, life all departments use the electronic unit of various sensitivity all in large quantities, the normal operation of social life must depend on the supply of electric power.The loss that power failure causes, by increasing, thus requires also constantly to improve to the power supply quality of device power supply (DPS) thereupon.Inverter is solve the power quality issues existed at present to provide a kind of effective approach, and the micro-grid system formed based on distributed power generation also more and more receives publicity.

Owing to comprising multiple electronic power switch type supply unit in microgrid load, as RHVC, rectifying installation etc., these equipment can be in operation and produce a large amount of harmonic waves, these harmonic waves can make power supply pollute, power supply quality is caused to decline, feed through to other homology loads, make it can not steady operation.Must take in nonlinear load when therefore designing inverter, and adopt the sine degree of effective control strategy control inverter output voltage.The gain of PI controller at fundamental frequency place is finite value, and ratio plural number integral controller levels off to infinity in the gain at first-harmonic place, can realize controlling the DAZ gene of the sinusoidal command signal of a certain fixed frequency.In systems in practice, because the bandwidth of ratio plural number integration is too low, be only tending towards infinite in the gain at fundamental frequency place, near fundamental frequency, gain is very little, can not reach good control effects when real system electric voltage frequency fluctuates.

Summary of the invention

The object of this invention is to provide a kind of contravarianter voltage control method suppressing voltage harmonic, under solving the nonlinear load existed in prior art, voltage distortion causes the problem of voltage total harmonic distortion.

The technical solution adopted in the present invention is, a kind of contravarianter voltage control method suppressing voltage harmonic, based on a kind of power source control system for micro, power source control system for micro comprises the inverter be connected with DC power supply, each phase of inverter exports and is connected with LC filter circuit respectively, and LC filter circuit is all connected with load by common bus; Inverter comprises single-phase inverter and three-phase inverter;

Concrete enforcement in accordance with the following methods:

Step 1, gathers inverter filtering capacitance voltage U _x, wherein x=(a, b, c), when inverter is single-phase inverter, inverter filtering capacitance voltage is U _a; When inverter is three-phase inverter, then inverter filtering capacitance voltage is U _a, U _b, U _c;

Step 2, by voltage reference value U _refxwith inverter filtering capacitance voltage U _xsubtract each other respectively, obtain voltage error value Δ U _x;

Step 3, by voltage error value Δ U _xregulate through improvement ratio plural number integral controller, obtain current reference value i _refx;

Step 4, by current reference value i _refxwith capacitance current i _cxsubtract each other, obtain current error Δ i _x;

Step 5, current error Δ i _xregulate through current regulator and produce modulation signal;

Step 6, modulation signal produces switch controlling signal through modulation module, thus controls inverter.

Feature of the present invention is also,

In step 3, the control mode of ratio plural number integral controller is:

By voltage error value Δ U _a, i.e. x _αsubstitute in transfer function formula (1) and obtain y _α, namely obtain current reference value:

$y_{\mathrm{\α}}=(x_{\mathrm{\α}}-m_{\mathrm{\β}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c}+x_{\mathrm{\α}}\·k_p;---\left(1\right)$

In formula, ω ₀for system works fundamental frequency, ω _cfor the frequency bandwidth of adjustment, according to electrical network allowable fluctuation range and ω _c=2.5rad/s, has k _pfor proportionality coefficient, k _ifor integral coefficient;

In formula (1), $m_{\mathrm{\β}}=(x_{\mathrm{\β}}-m_{\mathrm{\α}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c};---\left(2\right)$

In formula (2), $m_{\mathrm{\α}}=(x_{\mathrm{\α}}-m_{\mathrm{\β}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c};---\left(3\right)$

When inverter is three-phase inverter, in step 3, the control mode of ratio plural number integral controller is:

Steps A, by three-phase voltage error amount Δ U _a, Δ U _bwith Δ U _ccarry out abc/ α β conversion respectively through 3/2 static coordinate and obtain x _αand x _β;

Step B, by the x obtained in steps A _αand x _βsubstitute into respectively in formula (4) and formula (5), then can obtain y _α, y _β; Specific as follows:

$y_{\mathrm{\α}}=(x_{\mathrm{\α}}-m_{\mathrm{\β}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c}+x_{\mathrm{\α}}\·k_p;---\left(4\right)$

$y_{\mathrm{\β}}=(x_{\mathrm{\β}}+m_{\mathrm{\α}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c}+x_{\mathrm{\β}}\·k_p;---\left(5\right)$

In formula (4), $m_{\mathrm{\β}}=(x_{\mathrm{\β}}-m_{\mathrm{\α}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c};$

In formula (5), $m_{\mathrm{\α}}=(x_{\mathrm{\α}}-m_{\mathrm{\β}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c};$

Step C, by the y obtained in step B _αand y _βthree-phase current set-point i is obtained through α β/abc conversion _refa, i _refband i _refc.

K is designed according to root-locus method or frequency method _p, k _i.

In step 5, current regulator is pure ratio or proportional plus integral control mode.

The invention has the beneficial effects as follows voltage controller adoption rate plural number integral controller, and the transfer function of comparative example plural number integral controller is improved, increase the bandwidth of ratio plural number integral controller, thus make system have good steady-state behaviour and interference free performance, solve the problem of real system electric voltage frequency fluctuation; Thus under can nonlinear load being improved, inverter voltage waveform quality problems.

Accompanying drawing explanation

Fig. 1 is a kind of circuit structure diagram suppressing single-phase inverter in the contravarianter voltage control method of voltage harmonic of the present invention;

Fig. 2 is a kind of circuit structure diagram suppressing three-phase inverter in the contravarianter voltage control method of voltage harmonic of the present invention;

Fig. 3 is a kind of theory diagram suppressing the contravarianter voltage control method of voltage harmonic of the present invention;

Fig. 4 is the theory diagram for the control method of single-phase inverter in method of the present invention;

Fig. 5 is the theory diagram for the control method of three-phase inverter in method of the present invention.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.

Principle of the present invention is: improve for ratio plural number integral control method, the transfer function after improvement is with the transfer function after this improvement for theoretical foundation, set the bandwidth of ratio plural number integral controller, thus increase bandwidth.

A kind of contravarianter voltage control method suppressing voltage harmonic of the present invention, based on a kind of power source control system for micro, this power source control system for micro comprises the inverter be connected with DC power supply, each phase of this inverter exports and is connected with LC filter circuit respectively, and this LC filter circuit is all connected with load by common bus;

Inverter comprises single-phase inverter and three-phase inverter, and as shown in Figure 1, DC bus passes through filter inductance L to the circuit structure of single-phase inverter after single-phase inverter _aoutput current i _la, then through filter capacitor C _aafter obtain single-phase inverter output voltage U _a, then be local load supplying.The linear single-phase load that local load can be resistance, electric capacity, inductance form or the non-linear single-phase load be made up of power electronic equipments such as diode rectifiers;

As shown in Figure 2, DC bus passes through three-phase filter inductance L to the circuit structure of three-phase inverter after three-phase two-level inverter _a, L _b, L _cobtain three-phase output current i _la, i _lb, i _lc, then through filter capacitor C _a, C _b, C _cafter obtain inverter three-phase export phase voltage U _a, U _b, U _c.This three-phase exports phase voltage U _a, U _b, U _cbe connected in local load, local load can be resistance, the linear load of electric capacity, inductance composition or the nonlinear load that is made up of power electronic equipments such as diode rectifiers;

As shown in Figure 3, and implement according to following steps:

Step 1, gathers inverter filtering capacitance voltage U _x, wherein x=(a, b, c), when inverter is single-phase inverter, inverter filtering capacitance voltage is U _a; When inverter is three-phase inverter, then inverter filtering capacitance voltage is U _a, U _b, U _c;

Step 2, by voltage reference value U _refxwith inverter filtering capacitance voltage U _xsubtract each other respectively, obtain voltage error value Δ U _x;

When inverter is three-phase inverter, then inverter filtering capacitance voltage is U _a, U _b, U _c, now, Δ U _xcomprise three kinds of situations, i.e. Δ U _a=U _refa-U _a, Δ U _b=U _refb-U _b, Δ U _c=U _refc-U _c; When inverter is single-phase inverter, then inverter filtering electric capacity is U _a, now, Δ U _xonly has a kind of situation, i.e. Δ U _a=U _refa-U _a;

Step 3, by voltage error value Δ U _xregulate through ratio plural number integral controller, obtain current reference value i _refx;

In step 3, ratio plural number integral controller comprises two kinds of control modes, is respectively:

When inverter is single-phase inverter, control method as shown in Figure 4, is specially:

By voltage error value Δ U _a, i.e. x _αsubstitution formula obtains y in (1) _α, namely obtain current reference value:

$y_{\mathrm{\α}}=(x_{\mathrm{\α}}-m_{\mathrm{\β}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c}+x_{\mathrm{\α}}\·k_p;---\left(1\right)$

In formula, ω ₀for system works fundamental frequency, ω _cfor the frequency bandwidth of adjustment, according to electrical network allowable fluctuation range and ω _c=2.5rad/s, has k _pfor proportionality coefficient, k _ifor integral coefficient; Wherein k _p, k _imethod for designing can according to root-locus method, frequency method etc.;

In formula (1), $m_{\mathrm{\β}}=(x_{\mathrm{\β}}-m_{\mathrm{\α}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c};---\left(2\right)$

In formula (2), $m_{\mathrm{\α}}=(x_{\mathrm{\α}}-m_{\mathrm{\β}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c};---\left(3\right)$

When inverter is three-phase inverter, control method as shown in Figure 5, is specially:

Steps A, by three-phase voltage error amount Δ U _a, Δ U _bwith Δ U _ccarry out abc/ α β conversion respectively through 3/2 static coordinate and obtain x _αand x _β;

Step B, by the x obtained in steps A _αand x _βsubstitute into respectively in formula (4) and formula (5), then can obtain y _α, y _β; Specific as follows:

$y_{\mathrm{\α}}=(x_{\mathrm{\α}}-m_{\mathrm{\β}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c}+x_{\mathrm{\α}}\·k_p;---\left(4\right)$

$y_{\mathrm{\β}}=(x_{\mathrm{\β}}+m_{\mathrm{\α}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c}+x_{\mathrm{\β}}\·k_p;---\left(5\right)$

In formula (4), $m_{\mathrm{\β}}=(x_{\mathrm{\β}}-m_{\mathrm{\α}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c};$

In formula (5), $m_{\mathrm{\α}}=(x_{\mathrm{\α}}-m_{\mathrm{\β}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c};$

Step C, by the y obtained in step B _αand y _βthree-phase current set-point i is obtained through α β/abc conversion _refa, i _refband i _refc;

Step 4, by current reference value i _refxwith capacitance current i _cxsubtract each other, obtain current error Δ i _x;

Step 5, current error Δ i _xregulate through current regulator and produce modulation signal;

In step 5, current regulator is pure ratio or proportional plus integral control mode;

Step 6, modulation signal produces switch controlling signal through modulation module, thus controls inverter.

The present invention by adding another controling parameters ω in traditional transfer function of ratio plural number integral controller _c, controling parameters ω _cnot only affect the bandwidth of ratio plural number integral controller, also affect the gain of ratio plural number integral controller, namely along with ω _cincrease, the gain at the non-fundamental frequency place of bandwidth sum of ratio plural number integral controller all increases, and the gain at fundamental frequency place is constant.Last again according to mains frequency allowable fluctuation range, the frequency bandwidth of design proportion plural number integral controller, makes to be improved by the voltage waveform quality of micro battery inverter under nonlinear load.

Claims (5)

1. one kind is suppressed the contravarianter voltage control method of voltage harmonic, it is characterized in that, based on a kind of power source control system for micro, described power source control system for micro comprises the inverter be connected with DC power supply, each phase of described inverter exports and is connected with LC filter circuit respectively, and described LC filter circuit is all connected with load by common bus; Described inverter comprises single-phase inverter and three-phase inverter;

Concrete enforcement in accordance with the following methods:

Step 1, gathers inverter filtering capacitance voltage U _x, wherein x=(a, b, c), when inverter is single-phase inverter, inverter filtering capacitance voltage is U _a; When inverter is three-phase inverter, then inverter filtering capacitance voltage is U _a, U _b, U _c;

Step 2, by voltage reference value U _refxwith inverter filtering capacitance voltage U _xsubtract each other respectively, obtain voltage error value Δ U _x;

Step 3, by voltage error value Δ U _xregulate through improvement ratio plural number integral controller, obtain current reference value i _refx;

Step 4, by current reference value i _refxwith capacitance current i _cxsubtract each other, obtain current error Δ i _x;

Step 5, current error Δ i _xregulate through current regulator and produce modulation signal;

Step 6, modulation signal produces switch controlling signal through modulation module, thus controls inverter.

2. a kind of contravarianter voltage control method suppressing voltage harmonic according to claim 1, is characterized in that, when inverter is single-phase inverter, in described step 3, the control mode of ratio plural number integral controller is:

By voltage error value Δ U _α, i.e. x _αsubstitute in transfer function formula and obtain y _α, namely obtain current reference value, transfer function formula is as follows:

In formula, ω ₀for system works fundamental frequency, ω _cfor the frequency bandwidth of adjustment, ω _c=2.5rad/s, k _pfor proportionality coefficient, k _ifor integral coefficient;

In formula (1), $m_{\mathrm{\β}}=(x_{\mathrm{\β}}-m_{\mathrm{\α}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+{2\mathrm{\ω}}_c};---\left(2\right)$

In formula (2), $m_{\mathrm{\α}}=(x_{\mathrm{\α}}-m_{\mathrm{\β}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+{2\mathrm{\ω}}_c}.---\left(3\right)$

3. a kind of contravarianter voltage control method suppressing voltage harmonic according to claim 1, is characterized in that, when inverter is three-phase inverter, in described step 3, the control mode of ratio plural number integral controller is:

Steps A, by three-phase voltage error amount Δ U _a, Δ U _bwith Δ U _ccarry out abc/ α β conversion respectively through 3/2 static coordinate and obtain x _αand x _β;

Step B, by the x obtained in steps A _αand x _βsubstitute into respectively in formula (4) and formula (5), then can obtain y _α, y _β; Specific as follows:

$y_{\mathrm{\α}}=(x_{\mathrm{\α}}-m_{\mathrm{\β}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c}+x_{\mathrm{\α}}\·k_p;---\left(4\right)$

$y_{\mathrm{\β}}=(x_{\mathrm{\β}}-m_{\mathrm{\α}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c}+x_{\mathrm{\β}}\·k_p;---\left(5\right)$

In formula (4), $m_{\mathrm{\β}}=(x_{\mathrm{\β}}-m_{\mathrm{\α}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c};$

In formula (5), $m_{\mathrm{\α}}=(x_{\mathrm{\α}}-m_{\mathrm{\β}}\frac{{\mathrm{\ω}}_0}{2k_i{\mathrm{\ω}}_c})\·\frac{2k_i{\mathrm{\ω}}_c}{s+2{\mathrm{\ω}}_c};$

Step C, by the y obtained in step B _αand y _βthree-phase current set-point i is obtained through α β/abc conversion _refa, i _refband i _refc.

4. a kind of contravarianter voltage control method suppressing voltage harmonic according to claim 2, is characterized in that, design k according to root-locus method or frequency method _p, k _i.

5. a kind of contravarianter voltage control method suppressing voltage harmonic as claimed in any of claims 1 to 4, is characterized in that, in described step 5, current regulator is pure ratio or proportional plus integral control mode.