CN105608244A - Distributed photovoltaic power generation system equivalent simulation model based on PSCAD (Power System Computer Aided Design)/EMTDC (Electromagnetic Transient Including DC) - Google Patents

Abstract

The invention belongs to the technical field of distributed photovoltaic power generation, particularly relates to a distributed photovoltaic power generation system equivalent simulation model based on PSCAD (Power System Computer Aided Design)/EMTDC (Electromagnetic Transient Including DC), and is suitable for simplifying a distributed power generation system simulation model in the PSCAD/EMTDC and carrying out equivalent simulation on large distributed power station in the PSCAD/EMTDC. The distributed photovoltaic power generation system equivalent simulation model comprises a photovoltaic array module, a photovoltaic array controllable voltage source module, an inverter controllable voltage source module, a MPPT (Maximum Power Point Tracking) control module of the photovoltaic array controllable voltage source module, a control module of the inverter controllable voltage source module, a two-phase rotating coordinate system to three-phase stationary coordinate system conversion module and an inverter side filtering inductance and equivalent power grid model, wherein the photovoltaic array module, the inverter controllable voltage source module and the inverter controllable voltage source module are connected through the inverter side filtering inductance and equivalent power grid model. A calculation data size can be reduced, simulation time is shortened, and calculation speed and efficiency can be obviously improved.

Description

Distributed photovoltaic power generation system emulation equivalent model based on PSCAD/EMTDC

Technical field

The invention belongs to distributed photovoltaic power generation technical field, relate in particular to a kind of dividing based on PSCAD/EMTDCCloth formula photovoltaic generating system emulation equivalent model, is applicable to distributed generation system emulation mould in PSCAD/EMTDCThe simplification of type, and in PSCAD/EMTDC, carry out the equivalent emulation in large-scale distributed power station, raising emulationSpeed and efficiency.

Background technology

At present, build distributed photovoltaic power generation system simulation model in PSCAD/EMTDC time, main circuit will be byPhotovoltaic simulation, current transformer and electrical network main circuit part and control circuit part composition. The major technique of this emulationDifficult point concentrates on the control of current transformer, obtains current transformer pulse generate part, wherein by various mathematical algorithmsCurrent transformer pulse generate part determines to be PWM modulation system or SVPWM modulation system by modulation system. No matterAdopt which kind of mode, all can make to exist in model the pulse signal of upper frequency to calculate, in order to make simulation waveform notDistortion, in PSCAD/EMTDC the sampling step length of photovoltaic current transformer model generally all several to tens about microseconds.In simulation process, in each switch step-length, program will produce a secondary data iteration, cause each Simulation Engineering meterCalculation data volume is huge, and simulation node quantity is restricted. Utilize PSCAD/EMTDC to carry out large-scale photovoltaic power stationVery difficulty of generating emulation, emulation cannot be carried out.

PSCAD represents: power system CAD (PowerSystemsComputerAidedDesign).EMTDC represents: the electro-magnetic transient (ElectromagneticTransientsincludingDC) that comprises straight-flow system.

Fig. 1 is existing three-phase photovoltaic grid-connected power system model main circuit structure figure. Comprise by photovoltaic array module,Dc bus module, three-phase voltage source type inverter (VSC) module, MPPT algoritic module, inverter moduleControl module, inverter SVPWM modulation module, filter module, three-phase voltage increasing transformer module, net sideFilter inductance, infinitely great electrical network.

In model, the power output of single solar cell or assembly is less, in emulation by single solar cell orAssembly forms array to meet the power generation needs of large Capacity Optical photovoltaic generating system by connection in series-parallel. At single photovoltaic electricOn the basis of pool model, simplify equivalence and set up photovoltaic array block mold. The parameter that model need to be inputted is illuminationStrength S, photovoltaic battery temperature T. The continuous off-state voltage that photovoltaic array produces directly charges to DC capacitor,Photovoltaic cell sends after direct current only through the inversion of one-level DC/AC, converts electrical network to frequently with identical amplitudeAlternating current is grid-connected, and wherein combining inverter completes parallel network reverse. The present invention adopts conductance increment method to realizeMPPT control algolithm, photovoltaic array is defeated, directly provides maximum power point by the calculating of MPPT control algolithmMagnitude of voltage is directly direct current mother using the output dc voltage of maximum power point as inverter control module input quantityLine voltage instruction V_ref. Inverter control mould only needs given reactive power instruction, output quantity is inverter mouldThe target voltage of piece AC. Target voltage obtains the control of inverter module through inverter SVPWM modulation modulePulse signal processed. Start pulse signal is directly given inverter. Cut-offfing of converter module modulates corresponding orderMark voltage, controls target thereby realize.

Summary of the invention

For above-mentioned the deficiencies in the prior art part, the invention provides a kind of based on PSCAD/EMTDCDistributed photovoltaic power generation system emulation equivalent model simplified structure, under PSCAD/EMTDC environment to distributedThe simplified structure of photovoltaic generating system simulation model. Object is in order to solve photovoltaic DC-to-AC converter in photovoltaic generating systemThe huge problem of Artificial switch emulation NONLINEAR CALCULATION amount.

The present invention is achieved by the following technical solutions:

Distributed photovoltaic power generation system emulation equivalent model based on PSCAD/EMTDC:

Comprise photovoltaic array module, photovoltaic array controllable voltage source module, inverter controllable voltage source module, lightThe MPPT control module of photovoltaic array controllable voltage source module, the control module of inverter controllable voltage source module,Two-phase rotational coordinates is tied to three phase static coordinate system modular converter, inverter side filter inductance and equivalent electric pessimistic concurrency control;

Wherein, photovoltaic array module directly and photovoltaic array controllable voltage source module, inverter controllable voltage source mouldPiece is connected with equivalent electric pessimistic concurrency control by inverter side filter inductance.

The MPPT control module of described photovoltaic array controllable voltage source module and inverter controllable voltage source moduleControl module part, the input signal of the MPPT control module of photovoltaic array controllable voltage source module is photovoltaicThe output voltage signal V of array_dcAnd current signal, be output as the target voltage of photovoltaic array port, by thisTarget voltage, as the control signal of photovoltaic array controllable voltage source module, is realized photovoltaic array and is followed the trail of maximum workRate control target; The input signal of the control module of inverter side controllable voltage source module is d shaft current instruction letterNumberWith q shaft current command signal, output signal is target voltage under two-phase reference axis, through coordinate system 3/2After conversion, be output as grid-connected point target voltage, using this target voltage as inverter side controllable voltage source moduleControl signal, realize the grid-connected control target of inverter side.

The voltage of described photovoltaic array controllable voltage source module and the output of inverter controllable voltage source module carrys out mouldIntend the modulation voltage that former inverter module DC voltage and AC port produce; Controlled through photovoltaic arrayThe control module of the control module of voltage source module and inverter side controllable voltage source module, obtains former inverter mouldThe target voltage of piece DC side and grid side port can as photovoltaic array controllable voltage source module and inverter sideThe control signal of control voltage source module.

The Mathematical Modeling of described photovoltaic array module: a desirable photovoltaic cell, in the time of illumination-constant, lightRaw electric current does not change with the duty of photovoltaic cell, therefore in equivalent circuit, can be regarded as a constant currentSource; The output characteristics equation that can be drawn photovoltaic cell by equivalent circuit is as follows:

$I=I_{ph}-I_o\[\exp \left(\frac{V+{\mathrm{IR}}_s}{nkT/q}\right)-1\]---\left(1\right);$

I_phFor the short circuit current under given light intensity;

$I_{ph}=I_{sc}\frac{G}{G_{ref}}\[1+{\mathrm{\α}}_T\left(T-T_{ref}\right)\]---\left(2\right);$

I in formula_scFor standard test condition T_ref=25 DEG C, intensity of illumination G_ref＝1000W/m²Under short circuit current;Parameter alpha_TCurent change temperature coefficient for reference under sunshine:

$I_o=I_{rs}\left(\frac{T}{T_{ref}}\right)\exp \[{\mathrm{qE}}_g\left(\frac{1}{T_{ref}}-\frac{1}{T}\right)/nk\]---\left(3\right);$

In formula: I_rsFor the solar cell diodes reverse saturation current under rated temperature. All the other parameters, q isElectron charge constant, is generally 1.60e^-19; K is Boltzmann's constant, is generally 1.38e^-23; N is diodeFactor of influence, E_gFor photovoltaic electric bandwidth;

Photovoltaic array module is made up of multiple photovoltaic module connection in series-parallel, thereby has improved the voltage and current of system,With the power of this increase system transmission; By N_cIndividual assembly series connection, N_bThe photovoltaic array mould that individual assembly composes in parallelThe output current of piece can be described as:

$I=N_b{I}_{ph}-N_b{I}_o\[\exp \left(\frac{V+{\mathrm{IR}}_s}{N_{c}AkT/q}\right)-1\]---\left(4\right);$

P＝VI(5)；

The output current I of photovoltaic array module and power output P are with the variation of photovoltaic array module output voltage VAnd change;

Photovoltaic maximum power Tracing Control (MPPT).

The control method of described photovoltaic maximum power Tracing Control (MPPT) is conductance increment method, concrete asUnder:

Sampled I (t) and V (t) are respectively photovoltaic array module t moment sampled point, are asked and are obtained by conductance increment methodPhotovoltaic array module output voltage reference value V_ref；

In the time that intensity of illumination changes, photovoltaic array output voltage can be followed the tracks of it in mode stably and change, andOrder is also less in oscillation amplitude and the power loss of maximum power point; In the control flow of conductance increment method, whereinI (t) and V (t) are respectively output current and the voltage of photovoltaic array module t moment sampled point, I (t-1) andV (t-1) is respectively output voltage and the electric current of photovoltaic array module t-l moment sampled point; Δ V, Δ I are tThe current/voltage difference in moment and t-l moment; Here first judge whether Δ V, Δ I are 0, if 0,Photovoltaic module is operated in maximum power point place, follows the tracks of and finishes; If be 0 when different, first by adjusting voltage,Making Δ V is 0, further adjusts Δ I, and making Δ I is 0; By DC voltage closed-loop control, make photovoltaic cellOutput voltage is close to maximum power point all the time; In deterministic process, the minimum of a value of a given permission, as Δ VWithin minimum zone, just can stop disturbance; By the step of narration, in PSCAD, set up MPPT and controlThe anti-true mode of device.

The Mathematical Modeling of described inverter controllable voltage source module is:

$\left\{\begin{array}{c}{L}_f\frac{{\mathrm{di}}_q}{dt}+{\mathrm{\ω}}_s{L}_f{i}_d+R_f{i}_q=e_q-v_q\\ L_f\frac{{\mathrm{di}}_d}{dt}+{\mathrm{\ω}}_s{L}_f{i}_q+R_f{i}_d=e_d-v_d\\ C_f\frac{{\mathrm{dv}}_{dc}}{dt}=i_q{s}_q+i_d{s}_d-i_L\end{array}\right.---\left(6\right);$

In formula, e_qAnd e_dBe respectively d, the q axle component of line voltage, i_qAnd i_dBe respectively and be input to former inversionThe d of device blocks current, q axle component, S_qAnd S_dBe respectively the d of switch function, q axle component; v_qAnd v_dPointQ, d axle component that Wei former inverter module AC output voltage; L_fFor former inverter module filtered electricalSense value, C_fFor former inverter module direct current capacitance, i_LFor the dynamic current of inductance; R_fFor former inverter mouldPiece equivalent resistance, ω_sFor mains frequency; v_dcFor former inverter module DC voltage.

The oriented approach of the Mathematical Modeling of described inverter controllable voltage source module is line voltage vector oriented:

For simplifying control algolithm, the d axle of synchronous speed coordinate system is oriented to line voltage vectorUpper, like this,The d of line voltage, the relation that q component is satisfied:

e_q＝0(7)；

The d shaft current instruction of the control module of inverter controllable voltage source moduleCan directly pass through photovoltaic arrayModule power output equation is obtained;

$i_d^{*}=\frac{2}{3}\frac{I_{pv}{v}_{dc}}{e_d}---\left(8\right);$

In like manner v_dcFor photovoltaic equivalent voltage source module voltage, I_pvFor photovoltaic array module output current value, e_dForThe d axle component of line voltage;

The q shaft current instruction of the control module of inverter controllable voltage source moduleCan obtain by through type;

In like manner v_dcFor photovoltaic equivalent voltage source module voltage, I_pvFor photovoltaic array module output current value, e_dForThe d axle component of line voltage; In formula, calculate, realize powerfactorcosφ operation;

After controlling, obtain the target voltage v of inverter module_qAnd v_d, by the target electricity under this dq coordinatePressure is done anti-Park Transformation and is obtained the command voltage under three-phase abc coordinate, the instead controllable electric of inverter moduleThe voltage instruction of potential source module, thus voltage source control completed.

Advantage of the present invention and beneficial effect are:

The present invention adopts described simplified model owing to taking no account of the break-make of power electronic devices in inverter, has omittedThe nonlinear simulation of electronic power switch process, has reduced calculated data amount, has shortened simulation time. This simplificationModel is ensureing, under enough computational accuracies, can to improve computational speed, and one of emulation is comprising numerous current transformer moulds, simulation efficiency improves more obvious when the large-scale distributed photovoltaic generation of piece the field.

Outstanding effect of the present invention, not only can embody the distributed power generation of master mould and control function, and having changedProgressive die type has improved simulation efficiency, significantly reduces the simulation calculating time, has saved EMS memory occupation, is extensive pointThe emulation of cloth formula module access electrical network provides effective emulation mode.

Below in conjunction with the drawings and specific embodiments, the present invention will be further described in detail.

Brief description of the drawings

Fig. 1 is existing three-phase photovoltaic grid-connected power system model main circuit structure figure;

Fig. 2 is simplification photovoltaic generating system model structure figure of the present invention;

Fig. 3 is the equivalent circuit of photovoltaic module battery of the present invention;

Fig. 4 is the control flow chart of conductance increment method of the present invention.

Detailed description of the invention

The present invention is a kind of distributed photovoltaic power generation system emulation equivalent model based on PSCAD/EMTDC.

The present invention has proposed the inverter module equivalent-simplification that affects computational speed to become controllable voltage source mould firstThe wiring construction of piece. According to the control principle of inverter module, inverter module in model is omitted, directly using canControl voltage source module replaces, and simulates the port voltage of inverter module output. Like this, in model, originally needA large amount of inverter modules that calculate are just replaced by the little controllable voltage source module of amount of calculation. With contravarianter voltage source mouldPiece is connected with electrical network, does not affect control principle and the external behavior of model, is emulation large-scale photovoltaic electricity generation systemUnder PSCAD/EMTDC environment, realize possibility is provided. Describe in detail below in conjunction with accompanying drawing.

Fig. 2 is simplified model main circuit structure figure of the present invention.

Simplified model of the present invention comprises photovoltaic array module, photovoltaic array controllable voltage source module, inverterThe MPPT control module of controllable voltage source module, photovoltaic array controllable voltage source module, inverter controllable voltageThe control module of source module, two-phase rotational coordinates are tied to three phase static coordinate system modular converter, inverter side filteringInductance, equivalent electric pessimistic concurrency control.

Photovoltaic array module directly with photovoltaic array controllable voltage source module, inverter side controllable voltage source module leads toCrossing inverter side filter inductance is connected with equivalent electric pessimistic concurrency control.

The control of the MPPT control module of photovoltaic array controllable voltage source module and inverter controllable voltage source moduleModule section, the input signal of the MPPT control module of photovoltaic array controllable voltage source module is photovoltaic arrayOutput voltage signal V_dcAnd current signal, be output as the target voltage of photovoltaic array port, by this target electricityPress the control signal as photovoltaic array controllable voltage source module, realize photovoltaic array and follow the trail of maximum power controlTarget. The input signal of the control module of inverter side controllable voltage source module is d shaft current command signalWithQ shaft current command signal, output signal is target voltage under two-phase reference axis, converts through coordinate system 3/2After, be output as grid-connected point target voltage, the control using this target voltage as inverter side controllable voltage source moduleSignal processed, realizes the grid-connected control target of inverter side.

Simplified model of the present invention is economized in distributed photovoltaic power generation system simulation model under PSCAD/EMTDC environmentOmit inverter module, also removed inverter DC voltage-stabilizing electric capacity and SVPWM modulation module simultaneously. Whole contraryBecome device module DC side and AC and use respectively photovoltaic array controllable voltage source module and inverter controllable voltage sourceModule replaces, and carrys out mould with the voltage that photovoltaic array controllable voltage source module and inverter controllable voltage source module are exportedIntend the modulation voltage that former inverter module DC voltage and AC port produce. Controlled through photovoltaic arrayThe control module of the control module of voltage source module and inverter side controllable voltage source module, obtains former inverter mouldThe target voltage of piece DC side and grid side port can as photovoltaic array controllable voltage source module and inverter sideThe control signal of control voltage source module. Contrast by explanatory note and Fig. 1 and Fig. 2 can be found out, the present inventionSimulation model in the inverter module of the power electronic devices composition in former simulation model is substituted, exist like thisThe numerical computations of just having saved the delicate level of power electronics nonlinear switching state in emulation, has reduced emulation to calculatingThe requirement of machine hardware, has reduced simulation time, makes the generating of large scale emulation photovoltaic generating system become possibility.

Thereby the realization of controlling is mainly the electric current that relies on control inverter DC voltage to affect on circuit to be come realNow control target. The present invention omits inverter module in model according to this principle, directly uses light in Fig. 2Photovoltaic array controllable voltage source module and inverter controllable voltage source module replace, and simulate inverter module DC sideThe port voltage of port voltage and the output of inverter device module AC. Introduce concrete alternative below.

The Mathematical Modeling of photovoltaic array module:

Be illustrated in figure 3 the equivalent circuit of photovoltaic cell. A desirable photovoltaic cell, in the time of illumination-constant,Photogenerated current does not change with the duty of photovoltaic cell, therefore in equivalent circuit, can be regarded as a perseveranceStream source. The output characteristics equation that can be drawn photovoltaic cell by equivalent circuit is as follows:

$I=I_{ph}-I_o\[\exp \left(\frac{V+{\mathrm{IR}}_s}{nkT/q}\right)-1\]---\left(1\right);$

I_phFor the short circuit current under given light intensity.

$I_{ph}=I_{sc}\frac{G}{G_{ref}}\[1+{\mathrm{\α}}_T\left(T-T_{ref}\right)\]---\left(2\right);$

I in formula_scFor standard test condition T_ref=25 DEG C, intensity of illumination G_ref＝1000W/m²Under short circuit current.Parameter alpha_TFor the curent change temperature coefficient with reference under sunshine

$I_o=I_{rs}\left(\frac{T}{T_{ref}}\right)\exp \[{\mathrm{qE}}_g\left(\frac{1}{T_{ref}}-\frac{1}{T}\right)/nk\]---\left(3\right);$

In formula: I_rsFor the solar cell diodes reverse saturation current under rated temperature. All the other parameters, q isElectron charge constant, is generally 1.60e^-19. K is Boltzmann's constant, is generally 1.38e^-23. N is diodeFactor of influence, E_gFor photovoltaic electric bandwidth,

Photovoltaic array module is made up of multiple photovoltaic module connection in series-parallel, thereby has improved the voltage and current of system,With the power of this increase system transmission. By N_cIndividual assembly series connection, N_bThe photovoltaic array mould that individual assembly composes in parallelThe output current of piece can be described as:

$I=N_b{I}_{ph}-N_b{I}_o\[\exp \left(\frac{V+{\mathrm{IR}}_s}{N_{c}AkT/q}\right)-1\]---\left(4\right);$

P＝VI(5)；

The output current I of photovoltaic array module and power output P are with the variation of photovoltaic array module output voltage VAnd change.

Photovoltaic maximum power Tracing Control (MPPT).

In the present invention, photovoltaic maximum power Tracing Control (MPPT) control method is that conductance increment method is:

Sampled I (t) and V (t) are respectively photovoltaic array module t moment sampled point, are asked and are obtained by conductance increment methodPhotovoltaic array module output voltage reference value V_ref。

In the time that intensity of illumination changes, photovoltaic array output voltage can be followed the tracks of it in mode stably and change, andOrder is also less in oscillation amplitude and the power loss of maximum power point. The control flow of conductance increment method is as Fig. 4Shown in.

Wherein I (t) and V (t) are respectively output current and the voltage of photovoltaic array module t moment sampled point,I (t-1) and V (t-1) are respectively output voltage and the electric current of photovoltaic array module t-l moment sampled point. Δ V,Δ I is the current/voltage difference in t moment and t-l moment. Here first judge whether Δ V, Δ I are 0, if0, photovoltaic module is operated in maximum power point place, follows the tracks of and finishes. If be 0 when different, first by adjustingVoltage, making Δ V is 0, further adjusts Δ I, making Δ I is 0. By DC voltage closed-loop control, make photovoltaicThe output voltage of battery is close to maximum power point all the time. In deterministic process, the minimum of a value of a given permission,When Δ V just can stop disturbance within minimum zone. By the step of narration, in PSCAD, set up MPPTController simulation model.

The Mathematical Modeling of inverter controllable voltage source module is:

$\left\{\begin{array}{c}{L}_f\frac{{\mathrm{di}}_q}{dt}+{\mathrm{\ω}}_s{L}_f{i}_d+R_f{i}_q=e_q-v_q\\ L_f\frac{{\mathrm{di}}_d}{dt}+{\mathrm{\ω}}_s{L}_f{i}_q+R_f{i}_d=e_d-v_d\\ C_f\frac{{\mathrm{dv}}_{dc}}{dt}=i_q{s}_q+i_d{s}_d-i_L\end{array}\right.---\left(6\right);$

In formula, e_qAnd e_dBe respectively d, the q axle component of line voltage, i_qAnd i_dBe respectively and be input to former inversionThe d of device blocks current, q axle component, S_qAnd S_dBe respectively the d of switch function, q axle component. v_qAnd v_dPointQ, d axle component that Wei former inverter module AC output voltage. L_fFor former inverter module filtered electricalSense value, C_fFor former inverter module direct current capacitance, i_LFor the dynamic current of inductance. R_fFor former inverter mouldPiece equivalent resistance, ω_sFor mains frequency. v_dcFor former inverter module DC voltage.

As can be seen from Figure 2, this model has omitted DC voltage-stabilizing capacitance module part, orientation compared with master mouldMode is line voltage vector oriented. The i.e. orientation side of the Mathematical Modeling of described inverter controllable voltage source moduleFormula is line voltage vector oriented:

For simplifying control algolithm, the d axle of synchronous speed coordinate system can be oriented to line voltage vectorUpper, like this,The d of line voltage, the relation that q component is satisfied:

e_q＝0(7)；

The d shaft current instruction of the control module of inverter controllable voltage source moduleCan directly pass through photovoltaic array mouldPiece power output equation is obtained.

$i_d^{*}=\frac{2}{3}\frac{I_{pv}{v}_{dc}}{e_d}---\left(8\right);$

In like manner v_dcFor photovoltaic equivalent voltage source module voltage, I_pvFor photovoltaic array module output current value, e_dForThe d axle component of line voltage.

The q shaft current instruction of the control module of inverter controllable voltage source moduleCan obtain by through type:

In like manner v_dcFor photovoltaic equivalent voltage source module voltage, I_pvFor photovoltaic array module output current value, e_dForThe d axle component of line voltage. In formula, calculate, realize powerfactorcosφ operation.

After controlling, obtain the target voltage v of inverter module_qAnd v_d, in the present invention by this dq coordinateUnder target voltage do anti-Park Transformation and obtain the command voltage under three-phase abc coordinate, instead inverter mouldThe voltage instruction of the controllable voltage source module of piece, thus voltage source control completed.

Outstanding effect of the present invention, not only can embody the distributed power generation of master mould and control function, and having changedProgressive die type has improved simulation efficiency, significantly reduces the simulation calculating time, has saved EMS memory occupation, is extensive pointThe emulation of cloth formula module access electrical network provides effective emulation mode.

Claims (7)

1. the distributed photovoltaic power generation system emulation equivalent model based on PSCAD/EMTDC, is characterized in that:

Comprise photovoltaic array module, photovoltaic array controllable voltage source module, inverter controllable voltage source module, lightThe MPPT control module of photovoltaic array controllable voltage source module, the control module of inverter controllable voltage source module,Two-phase rotational coordinates is tied to three phase static coordinate system modular converter, inverter side filter inductance and equivalent electric pessimistic concurrency control;

Wherein, photovoltaic array module directly and photovoltaic array controllable voltage source module, inverter controllable voltage source mouldPiece is connected with equivalent electric pessimistic concurrency control by inverter side filter inductance.

2. distributed photovoltaic power generation system emulation based on PSCAD/EMTDC according to claim 1 etc.Effect model, is characterized in that: MPPT control module and the inverter of described photovoltaic array controllable voltage source moduleThe control module part of controllable voltage source module, the MPPT control module of photovoltaic array controllable voltage source moduleInput signal is the output voltage signal V of photovoltaic array_dcAnd current signal, be output as the order of photovoltaic array portMark voltage, the control signal using this target voltage as photovoltaic array controllable voltage source module, realizes photovoltaicArray is followed the trail of maximum power control target; The input signal of the control module of inverter side controllable voltage source module isD shaft current command signalWith q shaft current command signalOutput signal is target voltage under two-phase reference axis,After coordinate system 3/2 conversion, be output as grid-connected point target voltage, using this target voltage as inverter sideThe control signal of controllable voltage source module, realizes the grid-connected control target of inverter side.

3. distributed photovoltaic power generation system emulation based on PSCAD/EMTDC according to claim 1 etc.Effect model, is characterized in that: described photovoltaic array controllable voltage source module and inverter controllable voltage source module are defeatedThe voltage going out is simulated the modulation voltage of former inverter module DC voltage and the generation of AC port;

Through the control module of photovoltaic array controllable voltage source module and the control of inverter side controllable voltage source moduleMolding piece, obtains the target voltage of former inverter module DC side and grid side port as photovoltaic array controllable electricThe control signal of potential source module and inverter side controllable voltage source module.

4. distributed photovoltaic power generation system emulation based on PSCAD/EMTDC according to claim 1 etc.Effect model, is characterized in that: the Mathematical Modeling of described photovoltaic array module:

A desirable photovoltaic cell, in the time of illumination-constant, photogenerated current is not with the duty of photovoltaic cellChange, therefore in equivalent circuit, can be regarded as a constant-current source; Can draw photovoltaic cell by equivalent circuitOutput characteristics equation is as follows:

$I=I_{ph}-I_o\[\exp \left(\frac{V+{\mathrm{IR}}_s}{nkT/q}\right)-1\]---\left(1\right);$

I_phFor the short circuit current under given light intensity;

$I_{ph}=I_{sc}\frac{G}{G_{ref}}\[1+{\mathrm{\α}}_T(T-T_{ref})\]---\left(2\right);$

I in formula_scFor standard test condition T_ref=25 DEG C, intensity of illumination G_ref＝1000W/m²Under short circuit current;Parameter alpha_TCurent change temperature coefficient for reference under sunshine:

$I_o=I_{rs}\left(\frac{T}{T_{ref}}\right)\exp \[{\mathrm{qE}}_g(\frac{1}{T_{ref}}-\frac{1}{T})/nk)---\left(3\right);$

In formula: I_rsFor the solar cell diodes reverse saturation current under rated temperature. All the other parameters, q isElectron charge constant, is generally 1.60e^-19; K is Boltzmann's constant, is generally 1.38e^-23; N is diodeFactor of influence, E_gFor photovoltaic electric bandwidth;

Photovoltaic array module is made up of multiple photovoltaic module connection in series-parallel, thereby has improved the voltage and current of system,With the power of this increase system transmission; By N_cIndividual assembly series connection, N_bThe photovoltaic array mould that individual assembly composes in parallelThe output current of piece can be described as:

$I=N_b{I}_{ph}-N_b{I}_o\[\exp \left(\frac{V+{\mathrm{IR}}_s}{N_{c}AkT/q}\right)-1\]---\left(4\right);$

P＝VI(5)；

The output current I of photovoltaic array module and power output P are with the variation of photovoltaic array module output voltage VAnd change;

Photovoltaic maximum power Tracing Control (MPPT).

5. distributed photovoltaic power generation system emulation based on PSCAD/EMTDC according to claim 4 etc.Effect model, is characterized in that: the control method of described photovoltaic maximum power Tracing Control (MPPT) is electricityLead method of addition, specific as follows:

Sampled I (t) and V (t) are respectively photovoltaic array module t moment sampled point, are asked and are obtained by conductance increment methodPhotovoltaic array module output voltage reference value V_ref；

In the time that intensity of illumination changes, photovoltaic array output voltage can be followed the tracks of it in mode stably and change, andOrder is also less in oscillation amplitude and the power loss of maximum power point; In the control flow of conductance increment method, whereinI (t) and V (t) are respectively output current and the voltage of photovoltaic array module t moment sampled point, I (t-1) andV (t-1) is respectively output voltage and the electric current of photovoltaic array module t-l moment sampled point; When Δ V, Δ I are tThe current/voltage difference in quarter and t-l moment; Here first judge whether Δ V, Δ I are 0, if 0, lightPhotovoltaic assembly is operated in maximum power point place, follows the tracks of and finishes; If be 0 when different,, first by adjusting voltage, makeΔ V is 0, further adjusts Δ I, and making Δ I is 0; By DC voltage closed-loop control, make the defeated of photovoltaic cellGo out voltage close to maximum power point all the time; In deterministic process, the minimum of a value of a given permission, when Δ, V existsWithin minimum zone, just can stop disturbance; By the step of narration, in PSCAD, set up MPPT controllerAnti-true mode.

6. distributed photovoltaic power generation system emulation based on PSCAD/EMTDC according to claim 4 etc.Effect model, is characterized in that: the Mathematical Modeling of described inverter controllable voltage source module is:

$\left\{\begin{array}{c}{L}_f\frac{{\mathrm{di}}_q}{dt}+{\mathrm{\ω}}_s{L}_f{i}_d+R_f{i}_q=e_q-v_q\\ L_f\frac{{\mathrm{di}}_d}{dt}-{\mathrm{\ω}}_s{L}_f{i}_q+R_f{i}_d=e_d-v_d\\ C_f\frac{{\mathrm{dv}}_{dc}}{dt}=i_q{s}_q+i_d{s}_d-i_L\end{array}\right.---\left(6\right);$

In formula, e_qAnd e_dBe respectively d, the q axle component of line voltage, i_qAnd i_dBe respectively and be input to former inversionThe d of device blocks current, q axle component, S_qAnd S_dBe respectively the d of switch function, q axle component; v_qAnd v_dPointQ, d axle component that Wei former inverter module AC output voltage; L_fFor former inverter module filtered electricalSense value, C_fFor former inverter module direct current capacitance, i_LFor the dynamic current of inductance; R_fFor former inverter mouldPiece equivalent resistance, ω_sFor mains frequency; v_dcFor former inverter module DC voltage.

7. distributed photovoltaic power generation system emulation based on PSCAD/EMTDC according to claim 6 etc.Effect model, is characterized in that: the oriented approach of the Mathematical Modeling of described inverter controllable voltage source module is electrical networkVoltage vector orientation:

For simplifying control algolithm, the d axle of synchronous speed coordinate system is oriented to line voltage vectorUpper, like this,The d of line voltage, the relation that q component is satisfied:

e_q＝0(7)；

The d shaft current instruction of the control module of inverter controllable voltage source moduleCan directly pass through photovoltaic array mouldPiece power output equation is obtained;

$i_d^{*}=\frac{2}{3}\frac{I_{pv}{v}_{dc}}{e_d}---\left(8\right);$

In like manner v_dcFor photovoltaic equivalent voltage source module voltage, I_pvFor photovoltaic array module output current value, e_dForThe d axle component of line voltage;

The q shaft current instruction of the control module of inverter controllable voltage source moduleCan obtain by through type;

In like manner v_dcFor photovoltaic equivalent voltage source module voltage, I_pvFor photovoltaic array module output current value, e_dForThe d axle component of line voltage; In formula, calculate, realize powerfactorcosφ operation;

After controlling, obtain the target voltage v of inverter module_qAnd v_d, by the target electricity under this dq coordinatePressure is done anti-Park Transformation and is obtained the command voltage under three-phase abc coordinate, the instead controllable electric of inverter moduleThe voltage instruction of potential source module, thus voltage source control completed.