CN203218889U - Universal grid-connected photoelectric power generation system dynamo-electric transient model - Google Patents

Abstract

The utility model relates to a universal grid-connected photoelectric power generation system dynamo-electric transient model which is characterized in that: the universal grid-connected photoelectric power generation system dynamo-electric transient model comprises a photovoltaic cell PV unit, a maximum power point tracking MPPT unit, a DC conversion unit, a DC link unit, a converter unit which comprises a current inner-loop controller, an inverter outer-loop control unit and a protective unit. An illumination intensity S and a photovoltaic cell temperature parameter T are input into an input end of the photovoltaic cell PV unit, and the output end of the photovoltaic cell PV unit outputs a power PV1 to the DC conversion unit and outputs a maximum power point voltage VPVM to the maximum power point tracking MPPT unit. The DC conversion unit outputs terminal voltage VPV1 to the photovoltaic cell PV unit. The maximum power point tracking MPPT unit outputs power point voltage VPVM1. DC-side power PPV3 from the DC conversion unit is input into the DC link unit. The universal grid-connected photoelectric power generation system dynamo-electric transient model can provides a universal mathematical model which is suitable for dynamo-electric transient analysis for grid-connected photovoltaic power generating systems that have the characteristics of: multiple structures, different forms and inner parameter secrecy. Analysis, design and control for various kinds of grid-connected photovoltaic power generating systems in a micro-grid system.

Description

A kind of general parallel net type photovoltaic generating system electromechanical transient model

Technical field

The utility model relates to a kind of general parallel net type photovoltaic generating system electromechanical transient model, is the modeling method of photovoltaic generating system in a kind of photovoltaic PV and the power system analysis field.Belong to electric power system power transmission and distribution technical field.

Background technology

Along with the development of new forms of energy, intelligent grid and little electric power network technique, the parallel net type photovoltaic generating system has been obtained widely and has been used, and has vast potential for future development.In the electrical network dynamic analysis that contains photovoltaic generating system, need to adopt the transient Model that has precision and efficient concurrently, in previously studying, the photovoltaic generating system model adopts two class models usually: a class is tide model, be about to it and be modeled as simple power source, do not consider its dynamic process, this class model often is called " trend " model, is only applicable to tidal current analysis, and can not be used for transient analysis.Another kind of corresponding circuit or the electromagnetic model of specific photovoltaic generating system foundation that be based on, concrete maximal power tracing (MPPT) control algolithm and inverter circuit and control logic thereof in the strict embodiment photovoltaic generating system, though satisfying the electrical network electromechanical transient, this class model analyzes requirement, but there are the following problems for it: (1) is because the internal structure (as single-stage or stage type) of photovoltaic generating system is different specifically different because of producer with control method (as various MPPT control strategy), cause its versatility poor, need be to different manufacturers, the modeling respectively of the photovoltaic generating system of model, workload is very big, efficient is low, does not also gear to actual circumstances; (2) circuit of institute's established model or electromagnetic model relate to the proprietary device interior parameter of each producer, and these inner parameters belong to trade secret a bit, are difficult to obtain relevant model parameter, bring difficulty to modeling; (3) circuit or electromagnetic model complexity, for guaranteeing precision, the calculating step-length arranges very low, seriously restricts the speed of analytical calculation, and efficient is low.

In sum, according to present intelligent grid and the development of little electric power network technique, need badly general model structure is set, with automatization level and the expansion calculating scale that improves simulation analysis.Need to analyze the common feature of existing all kinds of photovoltaic generating systems, and at the demand of electric power system electromechanical transient simulation, form a kind of modeling method of versatility.

The utility model content

The purpose of this utility model is for a kind of electromechanical transient model of general parallel net type photovoltaic generating system being provided, being applicable to large-scale power grid system electromechanical transient simulation.

The purpose of this utility model can reach by the following technical programs:

A kind of electromechanical transient model of general parallel net type photovoltaic generating system is characterized in that:

1) it comprises photovoltaic cell PV unit, maximal power tracing MPPT unit, DC converter unit, DC-link unit, contains inverter unit, inverter outer shroud control unit and protected location that current inner loop is controlled;

2) photovoltaic cell PV unit input comprises intensity of illumination end and photovoltaic battery temperature parameter input, and its output connects the input of DC converter unit, the voltage input end of maximal power tracing MPPT unit; The voltage input end of the output connection photovoltaic cell PV unit of DC converter unit, the input by switch connection DC-link unit, the voltage output end of its input connection DC-link unit, the output of maximal power tracing MPPT unit; The input of DC-link unit connects an output of DC converter unit, an output that contains the inverter unit of current inner loop control, an input of its output connection DC converter unit, an input of inverter outer shroud control unit; The input of inverter outer shroud control unit comprises DC side input power input, DC-link voltage input end, active power input and reactive power input, the reactive power reference qref input of DC-link voltage input end, DC-link, and the output of inverter outer shroud control unit comprises the shaft current component reference value output of output inverter; The inverter unit that contains current inner loop control comprises direct current power calculator, AC power calculator, phase-locked loop, inverter and dq/abc converter.

Further,

1) photovoltaic cell PV unit is provided with input, output variable, the relation between the two such as expression formula:

$\left\{\begin{array}{c}{I}_{\mathrm{<figure-callout\; id="1"\; label="PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">PV</figure-callout>}1}=f({\mathrm{<figure-callout\; id="1"\; label="V\; PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{PV}},S,T,...)=I_{\mathrm{sc}}^{\&prime;}\{1-C_1[e^{\frac{V_{\mathrm{PV}1}}{C_2{V}_{\mathrm{OC}}}}-1\left]\right\}\\ {\mathrm{<figure-callout\; id="1"\; label="P\; PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{PV}}=V_{\mathrm{PV}1}{I}_{\mathrm{<figure-callout\; id="1"\; label="PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">PV</figure-callout>}1}\end{array}\right.$

2) maximal power tracing MPPT unit is provided with input, output variable, the relation between the two such as expression formula:

$V_{\mathrm{<figure-callout\; id="1"\; label="PVm"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">PVm</figure-callout>}1}=\frac{e^{-\mathrm{\&tau;s}}}{1+\mathrm{Ts}}{V}_{\mathrm{PVm}}+\mathrm{\&Delta;}{V}_{\mathrm{PVm}}$

3) the DC converter unit is provided with input, output variable, and the relation between the two comprises two kinds of situations,

First kind of corresponding single-stage photovoltaic generating system of situation, expression formula is:

$\left\{\begin{array}{c}{P}_{\mathrm{PV}2}=f_1\left(P_{\mathrm{PV}1}\right)=P_{\mathrm{PV}1}\\ V_{\mathrm{PV}}=f_2(V_D,V_{\mathrm{PVm}1})=V_D\end{array}\right.$

Second kind of corresponding twin-stage of situation or multistage photovoltaic generating system, expression formula is:

$\left\{\begin{array}{c}{P}_{\mathrm{PV}2}=f_1\left(P_{\mathrm{PV}1}\right)={\mathrm{<figure-callout\; id="1"\; label="P\; PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{PV}}{\mathrm{\&eta;}}_{\mathrm{DC}}\\ V_{\mathrm{PV}}=f_2(V_D,V_{\mathrm{PVm}1})=V_{\mathrm{<figure-callout\; id="1"\; label="PVm"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">PVm</figure-callout>}1}\end{array}\right.$

4) the DC-link unit is provided with input, output variable, the relation between the two such as expression formula:

$\left\{\begin{array}{c}\frac{{\mathrm{dE}}_C}{\mathrm{dt}}=P_{\mathrm{PV}3}-P_{\mathrm{De}}\\ E_C=1/2{\mathrm{CV}}_D^2\end{array}\right.$

E wherein _CBe the energy of storing on the electric capacity.

5) inverter outer shroud control unit is provided with input, output variable, the relation between the two such as expression formula:

$\left\{\begin{array}{c}{I}_{d,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1=\frac{B_{d2}{s}^2+B_{d1}s+B_{d0}}{A_{d2}{s}^2+A_{d1}s+A_{d0}}(V_{D,\mathrm{ref}}-V_D)+k_{\mathrm{FWD}}\frac{P_{\mathrm{PV}3}}{V_D}\\ I_{d,\mathrm{ref}}=\mathrm{Sat}(I_{d,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1,I_{d,\max },I_{d,\min })\end{array}\right.$

$\left\{\begin{array}{c}{I}_{q,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1=\frac{B_{q2}{s}^2+B_{q1}s+B_{q0}}{A_{q2}{s}^2+A_{q1}s+A_{q0}}(Q_{\mathrm{ref}}^{\&prime;}-Q_e)\\ I_{q,\mathrm{ref}}=\mathrm{Sat}(I_{q,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1,I_{q,\max },I_{q,\min })\end{array}\right.$

6) converter cell that contains current inner loop control is provided with input, output variable, the relation between the two such as expression formula:

The employing transfer function is described, for:

$\left\{\begin{array}{c}{I}_d=\frac{b_{d2}{s}^2+b_{d1}s+b_{d0}}{a_{d2}{s}^2+a_{d1}s+a_{d0}}{I}_{d,\mathrm{ref}}\\ I_q=\frac{b_{q2}{s}^2+b_{q1}s+b_{q0}}{a_{q2}{s}^2+a_{q1}s+a_{q0}}{I}_{q,\mathrm{ref}}\end{array}\right.$

The utlity model has following outstanding beneficial effect:

1, adopts the utility model to can be the grid-connected photovoltaic power generation system that structure is various in the reality, form is different and inner parameter is maintained secrecy the universal Mathematical Modeling that electromechanical transient is analyzed that is applicable to is provided, be conducive in the microgrid entire system, analyze, design and control all kinds of grid-connected photovoltaic power generation systems.Versatility mainly finds expression in: be applicable to various internal structures (as single-stage or stage type) and the control method of photovoltaic generating system, can carry out modeling from external characteristic, need not to relate to the inner parameter of producer's task equipment, and can be suitable for the transient analysis application.

2, the utility model highly versatile, concrete manifestation in: a) be applicable to single stage type and stage type grid-connected photovoltaic system; B) be applicable to multiple different maximal power tracing control algolithm; C) be applicable to multiple inverter circuit structure and interior circular current control strategy thereof.

3, the model parameter of the utility model employing is device parameter and external characteristic parameter, and the former can be provided by producer, and the latter can obtain by certain external characteristic test, does not comprise the structure and the strategy or the algorithm parameter that relate to trade secret of producer's device interior controller.The utility model is parameter configuration flexibly, general order transfer function is all adopted in control as the inverter inner and outer rings, can express Dynamic Control Strategy and the response characteristic of ratio (P), proportional+integral (PI), proportional+integral+differential (PID) and various second order filters.

4, the utility model has comprised grid-connected photovoltaic system protection logic commonly used,, output overcurrent under-voltage as system and DC side overvoltage etc.

Description of drawings

Fig. 1 is the structural representation of the utility model specific embodiment 1.

Embodiment

Specific embodiment 1:

Fig. 1 constitutes specific embodiment of the utility model 1.

With reference to Fig. 1, the electromechanical transient model of a kind of general parallel net type photovoltaic generating system that the utility model relates to, it comprises photovoltaic cell PV unit, maximal power tracing MPPT unit, DC converter unit, DC-link unit, contains inverter unit, inverter outer shroud control unit and the protected location of current inner loop control; Photovoltaic cell PV unit input comprises intensity of illumination end and photovoltaic battery temperature parameter input, and its output connects the input of DC converter unit, the voltage input end of maximal power tracing MPPT unit; The voltage input end of the output connection photovoltaic cell PV unit of DC converter unit, the input by switch connection DC-link unit, the voltage output end of its input connection DC-link unit, the output of maximal power tracing MPPT unit; The input of DC-link unit connects an output of DC converter unit, an output that contains the inverter unit of current inner loop control, an input of its output connection DC converter unit, an input of inverter outer shroud control unit; The input of inverter outer shroud control unit comprises DC side input power input, DC-link voltage input end, active power input and reactive power input, the reactive power reference qref input of DC-link voltage input end, DC-link, and the output of inverter outer shroud control unit comprises the shaft current component reference value output of output inverter; The inverter unit that contains current inner loop control comprises direct current power calculator, AC power calculator, phase-locked loop, inverter and dq/abc converter.

Photovoltaic cell PV unit input input intensity of illumination S, photovoltaic battery temperature parameter T, its output is to DC converter unit power output P _V1, to maximal power tracing MPPT unit Maximum Power Output point voltage V _PVMThe DC converter unit is to photovoltaic cell PV unit output end voltage V _PV1, by switch to DC-link unit power output P _PV2And input is from the voltage V of DC-link unit _D, from the power points voltage V of maximal power tracing MPPT unit _PVM1Maximal power tracing MPPT unit power output point voltage V _PVM1The input of DC-link unit is from the DC side power P of DC converter unit _PV3, come the inverter side power P of the inverter unit of self-contained current inner loop control _DEAnd to DC converter unit, inverter outer shroud control unit output DC-link voltage V _DThe reference value V of inverter outer shroud control unit input DC-link voltage _DREF, DC-link DC side input power P _PV3, DC-link voltage V _D, inverter is to the active power P of ac grid system output _EAnd reactive power Q _E, reactive power reference qref Q _REFOr power factor and to d, the q shaft current component reference value I of the inverter unit output inverter that contains current inner loop control _DQ, I _REFThe inverter unit that contains current inner loop control comprises direct current power calculator, AC power calculator, phase-locked loop, inverter and dq/abc converter, d, the q shaft current component reference value I of input inverter _DQ, I _REF, the ac grid system bus three-phase voltage U _Abc, three-phase current I _AbcAnd to AC network output three-phase current I _Abc, the instantaneous active power P that injects to system _EAnd reactive power Q _EWith the inverter direct-flow side power P _DE

In the present embodiment,

1) photovoltaic cell PV unit is provided with input, output variable, the relation between the two such as expression formula:

$\left\{\begin{array}{c}{I}_{\mathrm{<figure-callout\; id="1"\; label="PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">PV</figure-callout>}1}=f({\mathrm{<figure-callout\; id="1"\; label="V\; PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{PV}},S,T,...)=I_{\mathrm{sc}}^{\&prime;}\{1-C_1[e^{\frac{V_{\mathrm{PV}1}}{C_2{V}_{\mathrm{OC}}}}-1\left]\right\}\\ {\mathrm{<figure-callout\; id="1"\; label="P\; PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{PV}}=V_{\mathrm{PV}1}{I}_{\mathrm{<figure-callout\; id="1"\; label="PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">PV</figure-callout>}1}\end{array}\right.$

Other parameters of photovoltaic cell PV unit comprise: T _RefFor standard cell temperature, its value are 25 ° of C; S _RefFor standard intensity of illumination, its value are 1000MW/m ²A, b, c are constants, and its representative value is a=0.0025/ ° of C, b=0.5, c=0.00288/ ℃.Short circuit current I under standard cell temperature and the standard intensity of illumination _Sc, open circuit voltage V _OC, the maximum power point electric current I _m, maximum power point voltage V _m, the relationship between expression formula between input, the output variable

$\left\{\begin{array}{c}{I}_{\mathrm{<figure-callout\; id="1"\; label="PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">PV</figure-callout>}1}=f({\mathrm{<figure-callout\; id="1"\; label="V\; PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{PV}},S,T,...)=I_{\mathrm{sc}}^{\&prime;}\{1-C_1[e^{\frac{V_{\mathrm{PV}1}}{C_2{V}_{\mathrm{OC}}}}-1\left]\right\}\\ {\mathrm{<figure-callout\; id="1"\; label="P\; PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{PV}}=V_{\mathrm{PV}1}{I}_{\mathrm{<figure-callout\; id="1"\; label="PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">PV</figure-callout>}1}\end{array}\right.$

V _pvm=V′ _m

Wherein:

${\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">C</figure-callout>}}_1=(1-\frac{{I^{\&prime;}}_m}{{I^{\&prime;}}_{\mathrm{sc}}})e^{\frac{{V^{\&prime;}}_{\mathrm{PVm}}}{C_2{V}_{\mathrm{OC}}}}$

$C_2=(\frac{{V^{\&prime;}}_{\mathrm{PVm}}}{V_{\mathrm{OC}}}-1){\left[\ln (1-\frac{{I^{\&prime;}}_m}{{I^{\&prime;}}_{\mathrm{sc}}})\right]}^{-1}$

ΔT=T-T _ref

$\mathrm{\&Delta;S}=\frac{S}{S_{\mathrm{ref}}}-1$

${I^{\&prime;}}_{\mathrm{sc}}=\frac{I_{\mathrm{sc}}S}{S_{\mathrm{ref}}}(1+\mathrm{a\&Delta;T})$

V' _oc=U _oc(1-cΔT)(1+bΔS)

${I^{\&prime;}}_m=\frac{I_{m}S}{S_{\mathrm{ref}}}(1+\mathrm{a\&Delta;T})$

V' _m=V _m(1-cΔT)(1+bΔS)

In the formula: I ' _Sc, V' _Oc, I ' _m, V' _mBe respectively I _Sc, V _Oc, I _m, V _mCorrection value under varying environment.

The relevant parameter of maximal power tracing MPPT unit comprises: τ is pure lag time constant, and T is the single order time constant, Δ V _PVmBe tracking error; Output variable is V _PVm1, be actual " maximum " power points voltage that obtains of MPPT control.

2) maximal power tracing MPPT unit is provided with input, output variable, the relation between the two such as expression formula:

$V_{\mathrm{<figure-callout\; id="1"\; label="PVm"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">PVm</figure-callout>}1}=\frac{e^{-\mathrm{\&tau;s}}}{1+\mathrm{Ts}}{V}_{\mathrm{PVm}}+\mathrm{\&Delta;}{V}_{\mathrm{PVm}}$

3) the DC converter unit is provided with input, output variable, and the relation between the two comprises two kinds of situations,

First kind of corresponding single-stage photovoltaic generating system of situation, expression formula is:

$\left\{\begin{array}{c}{P}_{\mathrm{PV}2}=f_1\left(P_{\mathrm{PV}1}\right)=P_{\mathrm{PV}1}\\ V_{\mathrm{PV}}=f_2(V_D,V_{\mathrm{PVm}1})=V_D\end{array}\right.$

Second kind of corresponding twin-stage of situation or multistage photovoltaic generating system, expression formula is:

$\left\{\begin{array}{c}{P}_{\mathrm{PV}2}=f_1\left(P_{\mathrm{PV}1}\right)={\mathrm{<figure-callout\; id="1"\; label="P\; PV"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">P</figure-callout>}}_{\mathrm{PV}}{\mathrm{\&eta;}}_{\mathrm{DC}}\\ V_{\mathrm{PV}}=f_2(V_D,V_{\mathrm{PVm}1})={\mathrm{<figure-callout\; id="1"\; label="V\; PVm"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{PVm}}\end{array}\right.$

4) the DC-link unit is provided with input, output variable, the relation between the two such as expression formula:

$\left\{\begin{array}{c}\frac{{\mathrm{dE}}_C}{\mathrm{dt}}=P_{\mathrm{PV}3}-P_{\mathrm{De}}\\ E_C=1/2{\mathrm{CV}}_D^2\end{array}\right.$

E wherein _CBe the energy of storing on the electric capacity;

Between the input of DC converter unit, output variable in the relational expression,

η _DCBe the efficient of DC conversion, following formula also can be expressed as:

$\left\{\begin{array}{c}{P}_{\mathrm{PV}2}=f_1\left(P_{\mathrm{PV}1}\right)=P_{\mathrm{PV}1}-P_{\mathrm{DCLoss}}\\ V_{\mathrm{PV}}=f_2(V_D,V_{\mathrm{PVm}1})={\mathrm{<figure-callout\; id="1"\; label="V\; PVm"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">V</figure-callout>}}_{\mathrm{PVm}}\end{array}\right.$

P _DCLossThe power loss of expression DC conversion.

5) inverter outer shroud control unit is provided with input, output variable, the relation between the two such as expression formula:

$\left\{\begin{array}{c}{I}_{d,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1=\frac{B_{d2}{s}^2+B_{d1}s+B_{d0}}{A_{d2}{s}^2+A_{d1}s+A_{d0}}(V_{D,\mathrm{ref}}-V_D)+k_{\mathrm{FWD}}\frac{P_{\mathrm{PV}3}}{V_D}\\ I_{d,\mathrm{ref}}=\mathrm{Sat}(I_{d,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1,I_{d,\max },I_{d,\min })\end{array}\right.$

$\left\{\begin{array}{c}{I}_{q,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1=\frac{B_{q2}{s}^2+B_{q1}s+B_{q0}}{A_{q2}{s}^2+A_{q1}s+A_{q0}}(Q_{\mathrm{ref}}^{\&prime;}-Q_e)\\ I_{q,\mathrm{ref}}=\mathrm{Sat}(I_{q,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1,I_{q,\max },I_{q,\min })\end{array}\right.$

In the inverter outer shroud control unit, relating to the direct voltage reference value of DC-link, is V for the stage photovoltaic single grid-connected system _PVm1, and for the stage type grid-connected photovoltaic system reference value V need be set in addition _D1

The Reactive Power Control mode that inverter adopts often adopts two kinds of patterns, that is: decide the reactive power pattern and decide the power factor pattern;

The control parameter, A _D2, A _D1, A _D0, B _D2, B _D1, B _D0, k _FWD, A _Q2, A _Q1A _Q0, B _Q2, B _Q1, B _Q0, I _{D, max}, I _{D, min}, I _{Q, max}, I _{Q, min}, k _FWD

Relation between input, the output variable adopts transfer function to describe, for:

$\left\{\begin{array}{c}{I}_{d,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1=\frac{B_{d2}{s}^2+B_{d1}s+B_{d0}}{A_{d2}{s}^2+A_{d1}s+A_{d0}}(V_{D,\mathrm{ref}}-V_D)+k_{\mathrm{FWD}}\frac{P_{\mathrm{PV}3}}{V_D}\\ I_{d,\mathrm{ref}}=\mathrm{Sat}(I_{d,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1,I_{d,\max },I_{d,\min })\end{array}\right.$

$\left\{\begin{array}{c}{I}_{q,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1=\frac{B_{q2}{s}^2+B_{q1}s+B_{q0}}{A_{q2}{s}^2+A_{q1}s+A_{q0}}(Q_{\mathrm{ref}}^{\&prime;}-Q_e)\\ I_{q,\mathrm{ref}}=\mathrm{Sat}(I_{q,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1,I_{q,\max },I_{q,\min })\end{array}\right.$

Wherein:

(1) Sat (x, x _Max, x _Min) the expression saturation function, it is defined as:

$\mathrm{Sat}(x,x_{\max },x_{\min })=\left\{\begin{array}{cc}{x}_{\max }& x>x_{\max }\\ x_{\min }& x<x_{\min }\\ x& x_{\min }\&le;x\&le;x_{\max }\end{array}\right.$

3) I _{D, max}, I _{D, min}, I _{Q, max}, I _{Q, min}Can be provided by modeling parameters separately, also can only provide the maximum limit flow valuve I of inverter _Max, then

$\left\{\begin{array}{c}{I}_{d,\max }=I_{\max }\\ I_{d,\min }=-I_{\max }\\ I_{q,\max }=\sqrt{I_{\max }^2-I_{d,\mathrm{ref}}}\\ I_{q,\min }=-I_{q,\max }\end{array}\right.$

(4) k _FWDBe active power feedfoward control pattern, k _FWDFeedfoward control, k are not adopted in=0 expression _FWDFeedfoward control is adopted in=1 expression;

(5) the voltage reference value V of DC-link _{D, ref}Value mode: for stage photovoltaic single grid-connected system V _{D, ref}=V _PVm1, and for stage type grid-connected photovoltaic system V _{D, ref}=V _D1

6) converter cell that contains current inner loop control is provided with input, output variable, the relation between the two such as expression formula:

The employing transfer function is described, for:

$\left\{\begin{array}{c}{I}_{d,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1=\frac{B_{d2}{s}^2+B_{d1}s+B_{d0}}{A_{d2}{s}^2+A_{d1}s+A_{d0}}(V_{D,\mathrm{ref}}-V_D)+k_{\mathrm{FWD}}\frac{P_{\mathrm{PV}3}}{V_D}\\ I_{d,\mathrm{ref}}=\mathrm{Sat}(I_{d,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1,I_{d,\max },I_{d,\min })\end{array}\right.$

$\left\{\begin{array}{c}{I}_{q,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1=\frac{B_{q2}{s}^2+B_{q1}s+B_{q0}}{A_{q2}{s}^2+A_{q1}s+A_{q0}}(Q_{\mathrm{ref}}^{\&prime;}-Q_e)\\ I_{q,\mathrm{ref}}=\mathrm{Sat}(I_{q,\mathrm{<figure-callout\; id="1"\; label="ref"\; filenames="HDA00002109037900011.png"\; state="\{\{state\}\}">ref</figure-callout>}}^1,I_{q,\max },I_{q,\min })\end{array}\right.$

Contain in the inverter model of current inner loop control, relate to device parameter: inverter efficiency η _InVOr loss P _InvLossControl parameter: a _D2, a _D1, a _D0, b _D2, b _D1, b _D0, a _Q2, a _Q1, a _Q0, b _Q2, b _Q1, b _Q0, I _{D, max}, I _{D, min}, I _{Q, max}, I _{Q, min}, k _FWD

(2) output variable is:

i _Abc: the three-phase current that inverter injects to the ac grid system side;

P _e, Q _e: instantaneous active power and reactive power that inverter injects to system;

P _De: inverter direct-flow side power.

(3) the model internal-internal contains: inverter, dq/abc conversion, phase-locked loop, AC power are calculated and direct current power is calculated, wherein

I) transfer function model of inverter:

$\left\{\begin{array}{c}{I}_d=\frac{b_{d2}{s}^2+b_{d1}s+b_{d0}}{a_{d2}{s}^2+a_{d1}s+a_{d0}}{I}_{d,\mathrm{ref}}\\ I_q=\frac{b_{q2}{s}^2+b_{q1}s+b_{q0}}{a_{q2}{s}^2+a_{q1}s+a_{q0}}{I}_{q,\mathrm{ref}}\end{array}\right.$

I wherein _d, I _qBe respectively the d of inverter, q shaft current component.

Ii) phase-locked loop adopts general phase-locked function in the current system analysis, is input as ac grid system side three-phase voltage u _Abc, be output as the angle θ of its positive sequence fundamental voltage component.

General transformation for mula in the current system analysis is adopted in iii) dq/abc conversion, is input as d-q coordinate system electric current I _DqBe output as the three-phase current i that injects to the ac grid system side _Abc

Iv) AC power is calculated, and adopts general instantaneous power computing formula in the current system analysis, is input as ac grid system side three-phase voltage u _AbcWith the three-phase current i of inverter to the injection of ac grid system side _Abc, be output as instantaneous active power and reactive power P that inverter injects to system _e, Q _e

V) direct current power is calculated, and its computational methods are:

P _De=P _e/η _Inv

η _InvBe the efficient of inverter, following formula also can be expressed as:

P _De=P _e-P _InvLoss

P _InvLossThe active power loss of expression inverter.

6) in Bao Hu the model,

(1) input variable is:

u _Abc: the three-phase voltage of the ac grid system bus that inverter inserts;

i _Abc: the three-phase current that inverter injects to the ac grid system side;

V _D: the voltage of DC-link;

Protection definite value: system low-voltage threshold V _{AC, min}(instantaneous effective value, default be set to rated voltage 20%), system low-voltage hysteresis value Δ V _{AC, min}(instantaneous effective value, default be set to rated voltage 5%), inverter allows current maxima I _{Inv, max}(instantaneous effective value), DC-link voltage max V _{D, max}

(2) output variable is:

P1: protection operation 1;

P2: protection operation 2;

(3) relation between input, the output variable, namely protect logic to be respectively:

Logical one: as ac grid system voltage u _AbcCorresponding instantaneous effective value is lower than system low-voltage threshold V _{AC, min}The time, P1 moves in inverter to the ac grid system side three-phase current i that injects _AbcSwitch to 0 value, P2 moves in the DC side input power P with DC-link simultaneously _PV3Switch to 0 value; Work as u _AbcCorresponding instantaneous effective value is from being lower than system low-voltage threshold V _{AC, min}Progressively rise and reach V _{AC, min}+ Δ V _{AC, min}The time, whole photovoltaic power generation grid-connecting system restart, P1 and P2 switch back normally (non-0) link position;

Logic 2: as the three-phase current i of inverter to the injection of ac grid system side _AbcCorresponding instantaneous effective value is higher than inverter and allows current maxima I _{Inv, max}The time, P1 moves in inverter to the ac grid system side three-phase current i that injects _AbcSwitch to 0 value, P2 moves in the DC side input power P with DC-link simultaneously _PV3Switch to 0 value; Restart whole photovoltaic power generation grid-connecting system according to calculating needs then, P1 and P2 switch back normally (non-0) link position;

Logic 3: as DC-link voltage V _DBe higher than DC-link voltage max V _{D, max}The time, P1 moves in inverter to the ac grid system side three-phase current i that injects _AbcSwitch to 0 value, P2 moves in the DC side input power P with DC-link simultaneously _PV3Switch to 0 value; Restart whole photovoltaic power generation grid-connecting system according to calculating needs then, P1 and P2 switch back normally (non-0) link position;

More than 3 protection logics can divide and arrange according to analyzing the needs selection portion, even arrange.

The utility model provides a kind of electromechanical transient model of general parallel net type photovoltaic generating system, can adopt several different methods to realize in concrete analysis, includes but not limited to:

(1) the utility model model tormulation is discrete or continuous state equation and algebraic equation form;

(2) the utility model model tormulation is discrete or continuous transfer function form;

(3) in various analysis software, adopt circuit and realize model of the present utility model or/and various functional module is combined into;

(4) Combination application of above-mentioned implementation method.

The above; it only is the specific embodiment of the utility model the best; but protection range of the present utility model is not limited thereto; anyly be familiar with those skilled in the art in the scope that the utility model discloses; be equal to replacement or change according to the technical solution of the utility model and utility model design thereof, all belonged to protection range of the present utility model.

Claims (1)

1. the electromechanical transient model of a general parallel net type photovoltaic generating system is characterized in that:

1) it comprises photovoltaic cell PV unit, maximal power tracing MPPT unit, DC converter unit, DC-link unit, contains inverter unit, inverter outer shroud control unit and protected location that current inner loop is controlled;

2) photovoltaic cell PV unit input comprises intensity of illumination end and photovoltaic battery temperature parameter input, and its output connects the input of DC converter unit, the voltage input end of maximal power tracing MPPT unit; The voltage input end of the output connection photovoltaic cell PV unit of DC converter unit, the input by switch connection DC-link unit, the voltage output end of its input connection DC-link unit, the output of maximal power tracing MPPT unit; The input of DC-link unit connects an output of DC converter unit, an output that contains the inverter unit of current inner loop control, an input of its output connection DC converter unit, an input of inverter outer shroud control unit; The input of inverter outer shroud control unit comprises DC side input power input, DC-link voltage input end, active power input and reactive power input, the reactive power reference qref input of DC-link voltage input end, DC-link, and the output of inverter outer shroud control unit comprises the shaft current component reference value output of output inverter; The inverter unit that contains current inner loop control comprises direct current power calculator, AC power calculator, phase-locked loop, inverter and dq/abc converter.

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