CN104065103B - A kind of photovoltaic Boost double-closed-loop control method of photovoltaic energy storage system - Google Patents

Abstract

Present invention is disclosed a kind of photovoltaic Boost double-closed-loop control method of photovoltaic energy storage system, under photovoltaic Boost is in constant current-supplying duty, photovoltaic Boost outfan gathers electric current and voltage signal and feeds back to the electric current loop pi regulator of photovoltaic Boost.The control method outer shroud of the present invention is Boost circuit output-voltage loop, can improve output voltage waveforms, improves stable state accuracy and Immunity Performance；Internal ring is Boost circuit inductive current ring, can improve the dynamic property of system.Whole control method can obtain stable DC bus-bar voltage, compared with the MPPT control strategy of existing photovoltaic side Boost, so that the stability contorting of whole photovoltaic energy storage system, the control complexity of the whole system simultaneously also reduced.

Description

A kind of photovoltaic Boost double-closed-loop control method of photovoltaic energy storage system

Technical field

The present invention relates to photovoltaic energy storage field, particularly relate to the double of photovoltaic side BOOST converter in photovoltaic energy storage system and close Ring control strategy.

Background technology

Traditional photovoltaic system, photovoltaic Boost control strategy mostly uses MPPT maximum power point tracking (Maximum Power Point Tracking, MPPT) pattern, it is possible to obtain maximum generating efficiency, and obtain the benefit of optimum.

In photovoltaic energy storage system, power inverter includes photovoltaic side Boost, battery side One Buck-Boost converter body And load-side full-bridge inverter.Three changers all jump on common DC bus, thus form a direct-current micro-grid.Its The MPPT control strategy of middle photovoltaic side Boost can not obtain stable DC bus-bar voltage, is unfavorable for that whole photovoltaic stores up The stability contorting of energy system, the algorithm controls complexity of the whole system simultaneously also increased.

Summary of the invention

The technical problem to be solved is to realize a kind of voltage electricity that can obtain stable DC bus-bar voltage Stream double-loop control strategy.

To achieve these goals, the technical solution used in the present invention is: the photovoltaic Boost of a kind of photovoltaic energy storage system becomes Parallel operation double-closed-loop control method, described photovoltaic energy storage system includes photovoltaic module, lithium ion battery, public electric wire net, local load And power inverter, described power inverter include photovoltaic side Boost, battery side One Buck-Boost converter body and Load-side full-bridge inverter, described lithium ion battery connects load-side full-bridge inverter through battery side One Buck-Boost converter body, Described photovoltaic module connects load-side full-bridge inverter through photovoltaic side Boost, and described changer connects load-side full-bridge Inverter connects this locality load；

Under photovoltaic Boost is in photovoltaic power supply duty, photovoltaic Boost outfan gathers electric current The electric current loop with voltage signal and feeding back to photovoltaic Boost and Voltage loop pi regulator.

The cross-over frequency f of after current ring will be compensated_icIt is arranged at the 1/15 of switching frequency fs, and by electric current loop pi regulator Corner frequency f_inIt is arranged on concussion link corner frequency and compensates between after current ring cross-over frequency

The inductance parameters of described photovoltaic Boost takes L=2mH, and dc-link capacitance parameter takes C=2000uF, directly Stream busbar voltage is 480V, and dutycycle takes 0.5, loads and is taken as R=46.08 Ω, institute according to the design of photovoltaic peak power output 5kW Stating pi regulator and include Voltage loop pi regulator and electric current loop pi regulator, wherein the parameter of electric current loop pi regulator is $\left\{\begin{array}{c}{K}_{\mathrm{ip}}=0.015\\ K_{\mathrm{ii}}=15\end{array}\right.,$ The parameter of Voltage loop pi regulator is $\left\{\begin{array}{c}{K}_{\mathrm{vp}}=2\\ K_{\mathrm{vi}}=500\end{array}\right..$

The break angular frequency of described concussion link is:Wherein D is switching tube S1 dutycycle, D '=1-D, C For dc-link capacitance.

The control method outer shroud of the present invention is Boost circuit output-voltage loop, can improve output voltage waveforms, improves stable state Precision and Immunity Performance；Internal ring is Boost circuit inductive current ring, can improve the dynamic property of system.Whole control method can To obtain stable DC bus-bar voltage, compared with the MPPT control strategy of existing photovoltaic side Boost, so that The stability contorting of whole photovoltaic energy storage system, the control complexity of the whole system simultaneously also reduced.

Accompanying drawing explanation

The content expressed every width accompanying drawing in description of the invention below is briefly described:

Fig. 1 photovoltaic energy storage system topological figure；

Fig. 2 Boost equivalent schematic diagram；

Fig. 3 Boost work control block diagram in cv mode；

Fig. 4 Boost work in cv mode electric current loop compensate after open loop amplitude-frequency performance plot；

Fig. 5 Boost circuit works Voltage loop control block diagram in cv mode；

The Voltage loop control block diagram that Fig. 6 simplifies；

Fig. 7 Boost circuit work in cv mode Voltage loop compensate after open loop amplitude-frequency performance plot.

Detailed description of the invention

Seeing Fig. 1 to understand, a kind of photovoltaic energy storage system includes photovoltaic module, lithium ion battery, public electric wire net, local load And power inverter, wherein power inverter include photovoltaic side Boost, battery side One Buck-Boost converter body and Load-side full-bridge inverter, this lithium ion battery connects load-side full-bridge inverter through battery side One Buck-Boost converter body, should Photovoltaic module connects load-side full-bridge inverter through photovoltaic side Boost, and this changer connects load-side full-bridge inverter Connecting this locality load, above three changer all jumps on common DC bus, thus forms a direct-current micro-grid.

See Fig. 2 to understand, (CV-Constant Voltage) pattern under system is in constant current-supplying state, control straight Stream busbar voltage is constant, and its control strategy uses the double-closed-loop control shown in Fig. 3, G_idAnd G (S)_viS () is that Boost circuit is set up Transmission function under small-signal alternate model, its expression is as follows:

$\left\{\begin{array}{c}{G}_{\mathrm{id}}\left(s\right)=\frac{{\hat{i}}_L\left(s\right)}{\hat{d}\left(s\right)}=\frac{V_{\mathrm{PV}}(\mathrm{RCS}+2)}{({\mathrm{LCS}}^2+\frac{L}{R}S+D^{\′2})D^{\′}R}\\ G_{\mathrm{vi}}\left(s\right)=\frac{{\hat{v}}_o\left(s\right)}{{\hat{i}}_L\left(s\right)}=\frac{D^{\′2}R-\mathrm{SL}}{(\mathrm{RCS}+2)D^{\′}}\end{array}\right.---\left(1\right)$

Wherein: C is dc-link capacitance, R is Boost circuit equivalent load, and D is switching tube S1 dutycycle, D '=1-D.

According to formula (1), electric current loop open-loop transfer function before compensation is:

$G_i\left(s\right)=\frac{K_{\mathrm{PWM}}\·V_{\mathrm{PV}}\·(\mathrm{RCS}+2)}{({\mathrm{LCS}}^2+\frac{L}{R}S+D^{\′2})D^{\′}R}---\left(2\right)$

Wherein: K_PWMBe input to the transmission function of dutycycle output for manipulator, its value is 1.

Actual parameter is substituted into formula (2), it is known that, in formula, denominator does not has real root, therefore controlled device contains a second order concussion Link:

$G\left(s\right)=\frac{V_{\mathrm{PV}}}{({\mathrm{LCS}}^2+\frac{L}{R}S+D^{\′2})D^{\′}R}=\frac{\frac{V_{\mathrm{dc}}}{\mathrm{LCR}}}{S^2+\frac{1}{\mathrm{RC}}S+\frac{D^{\′2}}{\mathrm{LC}}}---\left(3\right)$

The break angular frequency of this concussion link is:

${\mathrm{\ω}}_c=\frac{D^{\′}}{\sqrt{\mathrm{LC}}}---\left(4\right)$

The cross-over frequency f of after current ring will be compensated_icIt is arranged on switching frequency f_s(15kHz) at 1/15.By electric current loop PI The corner frequency fin of actuator is arranged on concussion link corner frequency and compensates between after current ring cross-over frequency, to ensure to mend Repay after current ring amplitude-versus-frequency curve and pass zero point with the slope of-20dB/dec, be taken as 1000rad/sec, i.e. have:

$\left\{\begin{array}{c}{f}_{\mathrm{in}}=\frac{1000}{2\mathrm{\π}}\\ f_{\mathrm{ic}}=\frac{f_s}{15}\end{array}\right.---\left(5\right)$

If electric current loop pi regulator parameter is:

$C_i\left(s\right)=\frac{K_{\mathrm{ip}}S+K_{\mathrm{ii}}}{S}---\left(6\right)$

Can be solved by below equation group and obtain current loop controller parameter:

$\left\{\begin{array}{c}\frac{K_{\mathrm{ii}}}{K_{\mathrm{ip}}}=1000\\ {|\frac{K_{\mathrm{ip}}S+K_{\mathrm{ii}}}{S}\·\frac{K_{\mathrm{PWM}}{V}_{\mathrm{PV}}(\mathrm{RCS}+2)}{({\mathrm{LCS}}^2+\frac{L}{R}S+D^{\′2})D^{\′}R}|}_{s=j2\mathrm{\π}{f}_{\mathrm{ic}}}=1\end{array}\right.---\left(7\right)$

Photovoltaic side inductance parameters takes L=2mH, and dc-link capacitance parameter takes C=2000uF, and DC bus-bar voltage is 480V, dutycycle takes 0.5, loads and is taken as R=46.08 Ω according to the design of photovoltaic peak power output 5kW.Above parameter is substituted into Formula (7) can solve electric current loop pi regulator parameter.Finally taking parameter is:

$\left\{\begin{array}{c}{K}_{\mathrm{ip}}=0.015\\ K_{\mathrm{ii}}=15\end{array}\right.---\left(8\right)$

See the Bert figure of electric current loop open-loop transfer function before and after Fig. 4 compensates to understand, compensate after current ring open loop transmission letter Number amplitude-versus-frequency curve passes zero point with the slope of-20dB/dec.System cross-over frequency is 2.6e+3rad/sec, Phase margin For 68.7deg, it is possible to obtain preferably dynamic characteristic and steady-state characteristic.

As it is shown in figure 5, using electric current loop closed loop transfer function as the part of controlled device.Owing to electric current loop bandwidth is the highest In Voltage loop, therefore the proportional component that closed loop transfer function Available Gain is 1 of electric current loop replaces, therefore the Voltage loop knot being simplified Structure is as shown in Figure 6.

According to formula (1), above-mentioned Voltage loop controlled device contains two corner frequencies.The cross-over frequency of Voltage loop after compensating Fvc is arranged on the 1/5 of electric current loop cross-over frequency fic.The corner frequency fvn of Voltage loop pi regulator is arranged on controlled device relatively After little corner frequency and compensation between Voltage loop cross-over frequency, to ensure that after compensating, Voltage loop amplitude-versus-frequency curve is with-20dB/ The slope of dec passes zero point, is taken as 250rad/sec.I.e. have:

$\left\{\begin{array}{c}{f}_{\mathrm{vn}}=\frac{250}{2\mathrm{\π}}\\ f_{\mathrm{vc}}=\frac{f_{\mathrm{ic}}}{5}\end{array}\right.---\left(9\right)$

If Voltage loop pi regulator parameter is:

$C_v\left(s\right)=\frac{K_{\mathrm{vp}}S+K_{\mathrm{vi}}}{S}---\left(10\right)$

Can be solved by below equation group and obtain Voltage loop controller parameter:

$\left\{\begin{array}{c}\frac{K_{\mathrm{vi}}}{K_{\mathrm{vp}}}=250\\ {|\frac{K_{\mathrm{vp}}S+K_{\mathrm{vi}}}{S}\·\frac{D^{\′2}R-\mathrm{SL}}{(\mathrm{RCS}+2)D^{\′}}|}_{s=j2\mathrm{\π}{f}_{\mathrm{vc}}}=1\end{array}\right.---\left(11\right)$

Relevant parameter is substituted into above formula, Voltage loop pi regulator parameter can be tried to achieve.Finally taking parameter is:

$\left\{\begin{array}{c}{K}_{\mathrm{vp}}=2\\ K_{\mathrm{vi}}=500\end{array}\right.---\left(12\right)$

The Bert figure of Voltage loop open-loop transfer function before and after compensating as shown in Figure 7.Voltage loop open-loop transfer function after compensation Amplitude-versus-frequency curve passes zero point with the slope of-20dB/dec.System cross-over frequency is 536rad/sec, and magnitude margin is 21.2dB, Phase margin is 66.5deg, it is possible to obtain preferably dynamic characteristic and steady-state characteristic.

Above in conjunction with accompanying drawing, the present invention is exemplarily described, it is clear that the present invention implements not by aforesaid way Restriction, as long as have employed the method design of the present invention and the improvement of various unsubstantialities that technical scheme is carried out, or without changing Enter and design and the technical scheme of the present invention are directly applied to other occasion, all within protection scope of the present invention.

Claims (2)

1. the photovoltaic Boost double-closed-loop control method of a photovoltaic energy storage system, it is characterised in that: described photovoltaic energy storage System includes photovoltaic module, lithium ion battery, public electric wire net, local load and power inverter, described power inverter bag Include photovoltaic side Boost, battery side One Buck-Boost converter body and load-side full-bridge inverter, described lithium ion battery Connecting load-side full-bridge inverter through battery side One Buck-Boost converter body, described photovoltaic module is through photovoltaic side Boost Connecting load-side full-bridge inverter, described load-side full-bridge inverter connects this locality load；

Under photovoltaic Boost is in photovoltaic power supply duty, photovoltaic Boost outfan gathers electric current and electricity Press signal and feed back to electric current loop and the Voltage loop pi regulator of photovoltaic Boost；

The cross-over frequency f of after current ring will be compensated_icIt is arranged at the 1/15 of switching frequency fs, and turning electric current loop pi regulator Folding frequency f_inIt is arranged on concussion link corner frequency and compensates between after current ring cross-over frequency；

The inductance parameters of described photovoltaic Boost takes L=2mH, and dc-link capacitance parameter takes C=2000uF, and direct current is female Line voltage is 480V, and dutycycle takes 0.5, loads and is taken as R=46.08 Ω, described PI according to the design of photovoltaic peak power output 5kW Actuator includes Voltage loop pi regulator and electric current loop pi regulator, and wherein the parameter of electric current loop pi regulator is $\left\{\begin{array}{c}{K}_{ip}=0.015\\ K_{ii}=15\end{array}\right.,$ The parameter of Voltage loop pi regulator is $\left\{\begin{array}{c}{K}_{vp}=2\\ K_{vi}=500\end{array}\right..$

The photovoltaic Boost double-closed-loop control method of photovoltaic energy storage system the most according to claim 1, its feature exists In: the break angular frequency of described concussion link is:Wherein D is switching tube S1 dutycycle, and D '=1-D, C are straight Stream bus capacitor, described switching tube S1 is the switching tube being connected across photovoltaic module the two poles of the earth in the Boost of photovoltaic side.