CN102158115B - Controlling and optimizing method of grid-combining three-phase voltage source converter in accumulator storage system - Google Patents

Abstract

The invention discloses a controlling and optimizing method of s grid-combining three-phase voltage source converter in an accumulator storage system, belonging to the field of electricity storage. The method comprises the following steps of: collecting signals of voltage and the three-phase electric grid current, performing Clark conversion and Park conversion to convert into two-phase fixed axis variable using as a feedback quantity, and counting charging power, comparing the feedback power with reference power, performing PI regulation and then outputting, wherein the output value is a reference value of active current, synchronously setting a reference value of passive current, comparing the reference values of the active current and the passive current with a rotating shaft two-phase current which is converted from the three-phase electric grid current, and performing the PI regulation to obtain a reference voltage, performing the Clark reverse conversion and the Park reverse conversion to obtain the fixed coordinate system voltage of the output end of the three-phase converter. The controlling and optimizing method of grid-combining three-phase voltage source converter in accumulator storage system can directly control the grid-combining active power of the converter, thus the loop is simple to control, the three-stage system is changed into a two-stage system, the system is easy to optimize and the system is stable and reliable.

Description

A kind of control optimization method of batteries to store energy grid-connected three-phase voltage source converter

Technical field

The present invention relates to electric power in the power industry energy storage technology that is incorporated into the power networks, be specifically related to a kind of a kind of control optimization method of the battery energy storage grid-connected three-phase voltage source converter system that designs for the stability of electrical network.

Background technology

development along with global new energy technology, especially the increasing development and utilization of wind energy and solar energy, fluctuation has appearred in the energy flow of electrical network, stability to electrical network has proposed very large challenge, in order to make electrical network more stable and strong, just need to there be device can play to power grid energy the effect of peak load shifting, begun now the research of electrical network energy-storage system abroad, China is along with the huge exploitation of this several years wind energy resourceses, also begun the research of energy-storage system, and battery energy storage system is one of the most promising energy storage mode in future, the core of batteries to store energy is the voltage source converter technology of energy capable of bidirectional flowing, research at voltage source converter in the past concentrates on wind energy mostly, the grid-connecting apparatus of solar energy and the PWM rectifier in industrial circle and Active Front End (AFE) field, relate to rarely having aspect the control of energy-storage system of accumulator three-phase voltage source current transformer, especially how to go to optimize the algorithm of whole control loop and setting method aspect just still less, great majority at the research three-phase voltage type current transformer to aspect the discharging and recharging of battery system, still with the method for controlling DC bus-bar voltage, storage battery is discharged and recharged, make like this control system extremely complexity and variable many, system is difficult to adjust.

Pertinent literature and the patent of openly studying at present energy-storage system of accumulator three-phase grid voltage-source type converter control method have: (1) Zhang Xing, Zhou Zhijian and perhaps quite outstanding " the reversible SPWM current transformer that is used for accumulator cell charging and discharging ", HeFei University of Technology's journal (natural science edition), 2007,30 (6); (2) " based on the battery charge and discharge device of Bidirectional variable-flow technology " of Zhang Shibin, Lin Zhongfan, Du Guiping, Liu Duoliang work, power electronic technology, 2008,42 (5); (3) Zhang Xingzhu " the PWM AC/DC current transformer design in battery charge and discharge device " electrician's electric energy new technology, 2002,21 (1); (4) Chinese patent: CN101478250 " a kind of energy accumulation current converter for liquid stream battery ".

the method that above-mentioned document and patent are mentioned or be in the situation that the accumulator cell charging and discharging method that the two-phase converter device adopts, for the direct current DC/DC system method to the accumulator cell charging and discharging management, the essence of these methods also rests on the mode of traditional accumulator cell charging and discharging management, utilize control DC/DC voltage to control discharging and recharging of storage battery, this method is feasible under the common environment to the storage battery impulse electricity, and want energy-storage system of accumulator is played effect to the regenerative resource peak load shifting via the voltage-type current transformer and to electrical network, that is just very difficult.Energy storage device not only needs battery system is charged and discharged the electric energy function and the modern times are incorporated into the power networks, the energy in bidirectional flow function, but also need to provide reactive power to regulate, and harmonic restraining function is arranged, such three-phase voltage source grid-connected converter gathers multi-function in integral whole, and is only the direction of following energy-storage system of accumulator grid-connected converter development.

Summary of the invention

in prior art, energy-storage system of accumulator three-phase voltage source current transformer discharges and recharges storage battery with the method for controlling DC bus-bar voltage in order to solve, make control system extremely complexity and variable many, the problem that system is difficult to adjust, the invention provides a kind of charging and discharging currents that need not to control by the voltage of controlling dc-link capacitance energy-storage system of accumulator, just can control accurately the control optimization method that discharges and recharges power three-phase voltage source current transformer of energy-storage system of accumulator, concrete scheme is as follows: a kind of control optimization method of batteries to store energy grid-connected three-phase voltage source converter, it is characterized in that comprising the following steps:

Step 1, utilize the single-phase voltage Hall element to gather the dc-link capacitance U at dc-link capacitance two ends _DCUtilize the monophase current Hall element to gather the charge in batteries electric current I _BattUtilize the three-phase voltage Hall element to gather electrical network three-phase voltage signal u _a, u _b, u _cUtilize three-phase current Hall element acquisition stream to cross the electrical network three-phase current signal i of induction reactance _a, i _b, i _c

Step 2, utilize phase-locked loop to detect three phase network voltage u _a, u _b, u _cAngular frequency _sWith phase angle θ _s

Step 3, the electrical network three-phase voltage u that collects _a, u _b, u _cWith current signal i _a, i _b, i _cThrough the conversion of Clark converter, become the amount in the two-phase fixed coordinate system: u _α, u _β, i _α, i _β

Step 4, the electric network voltage phase angle θ that utilizes phase-locked loop to obtain _s, the amount u in the two-phase fixed coordinate system _α, u _β, i _α, i _βThrough Park converter (10,11), become the amount u in the two-phase rotating coordinate system _d, u _q, i _d, i _q, make i _d, i _qObtain the ac-dc axis magnetic flux amount of impact and act on respectively u through multiplier _d, u _q, obtain feedback quantity

The direct-axis current i under rotational coordinates that step 5, utilization detect _dWith direct-axis voltage u _d1.5 times of product are come the approximate battery system charge power P that obtains _Batt, discharge and recharge power with setting

The numerical value that relatively obtains obtains accumulator cell charging and discharging active current reference value through the pi regulator I Hand over shaft current under rotating coordinate system

Reference quantity for the System Reactive Power electric current; Simultaneously with the converter grid-connected system set

Respectively with electrical network value of feedback i _dAnd i _qValue compares and passes through pi regulator II and pi regulator III and obtains Voltage Reference amount under the two-phase rotating coordinate system

With

Use the voltage reference quantity

With

Deduct respectively feedback quantity With

Obtain the output voltage reference quantity of converter when not considering that current harmonics suppresses,

With

Process Park inverse transformer obtains the converter output terminal Voltage Reference amount under the two-phase fixed coordinate system

With

Process Clark inverse transformer obtains the converter output terminal Voltage Reference amount under the two-phase fixed coordinate system again

With

Utilize

With

The signal that turns on and off through SVPWM converter output translator IGBT.

Another preferred version of the present invention: pi regulator I (15) is as follows in the parameter tuning step of current inner loop in parameter tuning step and the pi regulator II (16) of power outer shroud:

D-axis reference current under step 21, two-phase rotating coordinate system

With feedback current i _dError amount through relatively obtaining, the pi regulator II of process current inner loop obtains the current transformer output reference voltage through the SVPWM converter again, then is added in generation current i on induction reactance with the difference between line voltage _d

The PI parameter of step 22, current inner loop is according to the optimization of adjusting of the value of the inductance value of the switching frequency of SVPWM converter, induction reactance and resistance value, dc-link capacitance, and in ultimate current, ring is by an electric current first-order lag function representation relevant with the switching frequency value of SVPWM converter;

Step 23, this electric current first-order lag function is joined in battery system charge power closed loop, the PI parameter that power P I wherein controls is determined by the parameter of electric current first-order lag function;

The calculating that discharges and recharges power of step 24, battery system is by current transformer direct-axis current i _dWith direct-axis voltage u _d1.5 times of product are come approximate simulation, control outer shroud to consist of power.

Another preferred version of the present invention: described harmonic content With

The fundamental frequency value of passing through is

${18}^{{\mathrm{\ω}}_s},,{24}^{{\mathrm{\ω}}_s}.$

The energy-storage system of accumulator that the present invention proposes discharges and recharges Poewr control method, with traditional accumulator charging method, very large difference is arranged, when making the three-phase voltage source current transformer to be incorporated into the power networks, storage battery is carried out management of charging and discharging, the centre need not traditional DC/DC power supply, simultaneously can also provide power system reactive power, the method is simplified the control of energy-storage system of accumulator, and makes simultaneously control system simpler more stable.

The inventive method is applicable to need energy-storage system of accumulator in renewable energy system used, control and the optimization method of the three-phase voltage source current transformer that is incorporated into the power networks in redox flow battery energy storage system.To the control of photovoltaic grid-connected device, the control of the grid side current transformer of direct-driving type wind power generation system and need to use that in the occasion of grid type three-phase voltage source current transformer, the control method to current transformer also has reference.

Description of drawings

Fig. 1 energy-storage system of accumulator three-phase grid of the present invention type voltage source converter control system schematic diagram.

The be incorporated into the power networks transfer function schematic diagram of control optimization method of three-phase voltage source current transformer of Fig. 2 batteries to store energy of the present invention.

The topology diagram of Fig. 3 voltage source converter.

The simulated effect figure that Fig. 4 the inventive method is carried out.

Embodiment

The control optimization method of batteries to store energy grid-connected three-phase voltage source converter disclosed by the invention.by gathering the signal of three phase network voltage and current, be transformed into two-phase fixed axis variable as feedback quantity through Clark conversion and Park, and calculate simultaneously the power of charging, this feedback power and reference power are relatively, regulate through PI, output valve is the reference value of active current, setting simultaneously the reactive current reference value is zero, after both relatively also regulate through PI through the value that is transformed into the rotating shaft biphase current with the electrical network three-phase current of feedback, obtain reference voltage, through obtaining the fixed coordinate system voltage of needed 3-phase power converter output after Clark inverse transformation and Park inverse transformation.The present invention has cancelled the process of three-phase grid voltage source converter to regulating charge power by regulating DC bus-bar voltage in battery charging process, directly control the active power that current transformer is incorporated into the power networks, make control loop simple, make original third-order system become two rank systems, it is easier to optimize, and system is more reliable and more stable.

Embodiment one:

As shown in Figure 1, 2, 3, this programme comprises the high pass filter 26 of line voltage take a 100Kw voltage-source type current transformer as example illustrates implementation, induction reactance 5, and IGBT switching tube 14, DC side bus capacitor 4 and storage battery 1 and cable induction reactance 21 form.The charging reference power jumped at 0.03 second-the 100Kw(discharge from the 100Kw of beginning), dc-link capacitance 400uF, battery SOC state 50%, 25 ° of C of ambient temperature, the internal resistance of cell 0.3418 Ω, battery open circuit voltage 720V, cable resistance 0.001 Ω, cable reactance 10e-6H, switching frequency 15KHz, current PI adjuster Kp_i=2.4Ki_i=28.5, power P I adjuster Kp_p=0.00136, Ki_p=20.4;

The control optimization method of batteries to store energy grid-connected three-phase voltage source converter comprises the following steps:

I. utilize single-phase voltage Hall element 3 to gather the dc-link capacitance U at dc-link capacitance 4 two ends _DCUtilize monophase current Hall element 22 to gather battery charge I _BattUtilize three-phase voltage Hall element 23 to gather electrical network three-phase voltage signal u _a, u _b, u _cUtilize three-phase current Hall element 6 acquisition stream to cross the electrical network three-phase current signal i of induction reactance 5 _a, i _b, i _c

Ii. utilize phase-locked loop 20 to detect three phase network voltage u _a, u _b, u _cAngular frequency _sWith phase angle θ _s

Iii. the electrical network three-phase voltage that collects and current signal process Clark converter 8,9, become the amount in the two-phase fixed coordinate system, u _α, u _β, i _α, i _β, concrete formula is as follows:

$\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{u}_a\\ u_b\\ u_c\end{array}\right]$

$\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\left[\begin{array}{c}{i}_a\\ i_b\\ i_c\end{array}\right]$

Iv. the line voltage synchronous rotary angle θ that utilizes phase-locked loop 20 to obtain _s(ω t) is the amount u in the two-phase fixed coordinate system _α, u _β, i _α, i _βThrough Park converter 11 and 10, become the amount u in the two-phase rotating coordinate system _d, u _q, i _d, i _q, make i _d, i _qObtain the ac-dc axis magnetic flux amount of impact and act on respectively u through multiplier 12,13 _d, u _q, obtain feedback quantity

Concrete formula is as follows:

$\left[\begin{array}{c}{u}_d\\ u_q\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{\ωt}& -\cos \mathrm{\ωt}\\ \cos \mathrm{\ωt}& \sin \mathrm{\ωt}\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\end{array}\right]$

$\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{\ωt}& -\cos \mathrm{\ωt}\\ \cos \mathrm{\ωt}& \sin \mathrm{\ωt}\end{array}\right]\left[\begin{array}{c}{i}_{\mathrm{\α}}\\ i_{\mathrm{\β}}\end{array}\right]$

$u_d^{-}=u_d+\mathrm{\ωL}\·i_q$

$u_q^{-}=u_q-\mathrm{\ωL}\·i_d$

V. utilize the direct-axis current i under rotational coordinates that detects _dWith direct-axis voltage u _d1.5 times of product are come the approximate storage battery 1 charge power P that obtains _Batt, then discharge and recharge power with setting The numerical value that relatively obtains obtains accumulator cell charging and discharging active current reference value through pi regulator I 15

Set simultaneously the reactive current of converter grid-connected system

With electrical network value of feedback i _dAnd i _qValue compares and passes through pi regulator II 16, pi regulator III 17 obtains the Voltage Reference amount under the two-phase rotating coordinate system

With

Then deduct respectively value of feedback

With

At this moment consider the factor that influences each other between d axle and q axle, obtained converter in the output voltage reference quantity of not considering that current harmonics suppresses With

The converter output terminal Voltage Reference amount that process Park inverse transformation 18 obtains under the two-phase fixed coordinate system

With

The converter output terminal Voltage Reference amount that obtains under the two-phase fixed coordinate system through Clark inverse transformation 19 again

With

Concrete formula is as follows:

$\left[\begin{array}{c}{u}_d\\ u_q\end{array}\right]=\left[\begin{array}{cc}\mathrm{Lp}+R& -\mathrm{\ωL}\\ \mathrm{\ωL}& \mathrm{Lp}+R\end{array}\right]\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]+\left[\begin{array}{c}{u}_{\mathrm{GRd}}^{*}\\ u_{\mathrm{GRq}}^{*}\end{array}\right]$

$u_{\mathrm{GRd}}^{*}=-(K_{\mathrm{pi}}+\frac{K_{\mathrm{ii}}}{p})(i_d^{*}-i_d)+{\mathrm{\ωLi}}_q+u_d+u_{\mathrm{dh}}^{*}$

$u_{\mathrm{GRq}}^{*}=-(K_{\mathrm{pi}}+\frac{K_{\mathrm{ii}}}{p})(i_q^{*}-i_q)-{\mathrm{\ωLi}}_d+u_q+u_{\mathrm{qh}}^{*}$

Vi. utilize

With

Turn on and off signal 25 through what SVPWM converter 7 was realized converter IGBT, wherein hand over shaft current under rotating coordinate system

Reference quantity for the System Reactive Power electric current.

Wherein, pi regulator I (15) is as follows at parameter tuning method and the parameter tuning method of pi regulator II (16) on current inner loop of power outer shroud:

I. the d-axis reference current under the two-phase rotating coordinate system

With feedback current i _dError amount through relatively obtaining obtains the current transformer output reference voltage through SVPWM converter 7 again through the pi regulator II 16 of current inner loop, then is added in generation current i on induction reactance 5 with the difference between line voltage _d

Ii. wherein the PI parameter of current inner loop need to be adjusted according to the value of the inductance value of the switching frequency of SVPWM converter 7, induction reactance and resistance value, dc-link capacitance 4 and optimized out, in ultimate current, ring can represent with an electric current first-order lag function 24 relevant with the switching frequency value of SVPWM converter 7, and computational process is as follows:

$G_{\mathrm{oi}}=\frac{K_{\mathrm{pi}}(p+K_{\mathrm{ii}}/K_{\mathrm{pi}})}{p({\mathrm{\τ}}_{\mathrm{GR}}\·p+1)(\mathrm{Lp}+R)}$ Allow K _ii=0,

$\⇒G_{\mathrm{oi}}=\frac{K_{\mathrm{pi}}}{p\·L\·({\mathrm{\τ}}_{\mathrm{GR}}\·p+1)}=\frac{\frac{K_{\mathrm{pi}}}{L}}{p\·(1+{\mathrm{\τ}}_{\mathrm{GR}}\·p)}=\frac{\frac{1}{{2\mathrm{\τ}}_{\mathrm{GR}}}}{p\·(1+{\mathrm{\τ}}_{\mathrm{GR}}\·p)}$

$\frac{L}{K_{\mathrm{pi}}}=2\&CenterDot;{\mathrm{\&tau;}}_{\mathrm{GR}}\&RightArrow;K_{\mathrm{pi}}=\frac{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="HSA00000467098000011.png"\; state="\{\{state\}\}">L</figure-callout>}}{2\&CenterDot;{\mathrm{\&tau;}}_{\mathrm{GR}}}$

$G_{\mathrm{ci}}=\frac{{\mathrm{<figure-callout\; id="1"\; label="G\; oi"\; filenames="HSA00000467098000011.png"\; state="\{\{state\}\}">G</figure-callout>}}_{\mathrm{oi}}}{1+G_{\mathrm{oi}}}=\frac{1}{1+p\&CenterDot;\frac{L}{K_{\mathrm{pi}}}(1+{\mathrm{\&tau;}}_{\mathrm{GR}}\&CenterDot;p)}=\frac{1}{1+p\&CenterDot;{2\mathrm{\&tau;}}_{\mathrm{GR}}(1+{\mathrm{\&tau;}}_{\mathrm{GR}}\&CenterDot;p)}\&ap;\frac{1}{1+{2\mathrm{\&tau;}}_{\mathrm{GR}}\&CenterDot;p}$

Iii. this electric current first-order lag function is joined in battery system charge power closed loop 14,15,24, wherein the PI parameter of power P I control is determined by the parameter of electric current first-order lag function 24;

Iv. the calculating that discharges and recharges power of battery system is by current transformer direct-axis current i _dWith direct-axis voltage u _d1.5 times of product are come approximate simulation, and such power that just can consist of is controlled outer shroud, has avoided Direct Sampling charging current and charging voltage to do product, the power control outer shroud that is formed with at last error and is not easy to adjust.

As shown in Figure 4, after adopting the control system algorithm and setting method of the inventive method, the charge power of energy-storage system of accumulator is controlled more accurate, makes and follows response rapidly and stablize.

Claims (2)

1. the control optimization method of a batteries to store energy grid-connected three-phase voltage source converter is characterized in that comprising the following steps:

Step 1, utilize single-phase voltage Hall element (3) to gather the dc-link capacitance U at dc-link capacitance (4) two ends _DCUtilize monophase current Hall element (22) to gather the charge in batteries electric current I _BattUtilize three-phase voltage Hall element (23) to gather electrical network three-phase voltage signal u _a, u _b, u _cUtilize three-phase current Hall element (6) acquisition stream to cross the electrical network three-phase current signal i of induction reactance (5) _a, i _b, i _c

Step 2, utilize phase-locked loop (20) to detect three phase network voltage u _a, u _b, u _cAngular frequency _sWith phase angle θ _s

Step 3, the electrical network three-phase voltage u that collects _a, u _b, u _cWith current signal i _a, i _b, i _cThrough Clark converter (8,9) conversion, become the amount in the two-phase fixed coordinate system: u _α, u _β, i _α, i _β

Step 4, the electric network voltage phase angle θ that utilizes phase-locked loop (20) to obtain _s, the amount u in the two-phase fixed coordinate system _α, u _β, i _α, i _βThrough Park converter (10,11), become the amount u in the two-phase rotating coordinate system _d, u _q, i _d, i _q, make i _d, i _qObtain the ac-dc axis magnetic flux amount of impact and act on respectively u through multiplier (12,13) _d, u _q, obtain feedback quantity

The direct-axis current i under rotational coordinates that step 5, utilization detect _dWith direct-axis voltage u _d1.5 times of product are come approximate battery system (1) the charge power P that obtains _Batt, discharge and recharge power with setting The numerical value that relatively obtains obtains accumulator cell charging and discharging active current reference value through pi regulator I (15)

Hand over shaft current under rotating coordinate system Reference quantity for the System Reactive Power electric current; Simultaneously with the converter grid-connected system set

Respectively with electrical network value of feedback i _dAnd i _qValue compares, and obtains Voltage Reference amount under the two-phase rotating coordinate system through pi regulator II (16) and pi regulator III (17)

With

Use the voltage reference quantity

With

Deduct respectively feedback quantity

With Obtain the output voltage reference quantity of converter when not considering that current harmonics suppresses, consider respectively more on this basis the Voltage-output reference quantity when current harmonics suppresses With

Just obtain current transformer output voltage reference quantity With

Process Park inverse transformer (18) obtains the converter output terminal Voltage Reference amount under the two-phase fixed coordinate system

With

Pass through again Clark inverse transformer (19) and obtain converter output terminal Voltage Reference amount under the two-phase fixed coordinate system

With

Utilize

With

Through SVPWM converter (7) output translator IGBT(2) turn on and off signal (25).

2. control optimization method as claimed in claim 1, is characterized in that, pi regulator I (15) the power outer loop parameter adjust step and pi regulator II (16) as follows in the parameter tuning step of current inner loop:

D-axis reference current under step 21, two-phase rotating coordinate system With feedback current i _dError amount through relatively obtaining passes through SVPWM converter (7) through the pi regulator II (16) of current inner loop again and obtains the current transformer output reference voltage, then is added in generation current i on induction reactance (5) with the difference between line voltage _d

The PI parameter of step 22, current inner loop is according to the optimization of adjusting of the value of the inductance value of the switching frequency of SVPWM converter (7), induction reactance and resistance value, dc-link capacitance (4), and in ultimate current, ring is represented by an electric current first-order lag function (24) relevant with the switching frequency value of SVPWM converter (7);

Step 23, this electric current first-order lag function is joined in battery system charge power closed loop (14,15,24), the PI parameter that power P I wherein controls is determined by the parameter of electric current first-order lag function (24);

The calculating that discharges and recharges power of step 24, battery system is by current transformer direct-axis current i _dWith direct-axis voltage u _d1.5 times of product are come approximate simulation, control outer shroud to consist of power.

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