CN102354110A - Control method based on temperature variation for maximum power point tracking of photovoltaic generation system and device thereof - Google Patents

Abstract

The invention relates to a control method based on temperature variation for maximum power point tracking (MPPT) of a photovoltaic generation system and a device thereof, which mainly aim to solve the technical problems of no temperature tracking and low overall output efficiency in a traditional control method. The invention has the technical scheme: the control method based on the temperature variation for the MPPT of the photovoltaic generation system comprises the following steps: working out a voltage increment, i.e. voltage searching step deltaupv (t, deltaT), on a power voltage curve based on the temperature variation for a photovoltaic generation array according to a formula; dynamically searching a real-time power calculated value deltaP (t, deltaT) related with the temperature variation through controlling the voltage increment; if the temperature does not vary, controlling in a traditional method; if the temperature varies, dynamically adjusting the voltage searching step in time, and searching the real-time power calculated value deltaP (t, deltaT) related with the temperature variation to realize the control on the MPPT of the photovoltaic generation array. The device comprises circuits: a real-time environment temperature detection information auxiliary circuit 1, a master control circuit 2 and the like.

Description

Maximum power point of photovoltaic power generation system is followed the tracks of control method and the device based on temperature variation

Technical field

The present invention relates to a kind of maximum power point of photovoltaic power generation system and follow the tracks of (MPPT) control method and device based on temperature variation.It belongs to a kind of control method and device of MPPT during based on the solar energy photovoltaic system temperature variation.

Background technology

The output voltage current curve of solar energy power generating array has characteristic of nonlinear.Photovoltaic power generation array can be operated in different output voltage, but has only output when a certain magnitude of voltage, and the output power of photovoltaic system just can reach maximum power point.The disturbance observation has been proposed at present, conductance increment method, the control method of multiple MPPT maximum power point tracking such as adaptive method (MPPT) both at home and abroad.Because MPPT mainly is subjected to the influence of day illuminance and environment temperature, but above-mentioned all control methods consider that day illuminance is the primary variables factor more, and has ignored the restriction of environment temperature to MPPT.Therefore, above-mentioned all methods were effective when externally variation of ambient temperature was slow, but ambient temperature is when taking place sharply to change, especially on the grassland, desert and remote mountain areas, it is low that above-mentioned various control methods are followed the trail of the slack-off and whole output efficiency of speed.Be difficult to search new MPPT fast, thereby cause energy loss and mistake control possibly occur.

Summary of the invention

The objective of the invention is to solve existing control method and exist slow, no temperature tracking of tracking speed and the low technical matters of whole output efficiency, provide a kind of and follow the tracks of control method and device based on temperature variation based on the maximum power point of photovoltaic power generation system that temperature variation control maximum power point of photovoltaic power generation system is followed the tracks of and whole output efficiency is high.

The present invention solves the problems of the technologies described above the technical scheme that adopts to be: maximum power point of photovoltaic power generation system is followed the tracks of (MPPT) control method based on temperature variation; It is according to formula, and calculating photovoltaic power generation array is voltage step-size in search Δ u based on the voltage increment on the power voltage curve of temperature variation _Pv(t, Δ T) is voltage step-size in search Δ u through the voltage increment of controlling on this array power voltage curve _Pv(t, Δ T) dynamically seeks the realtime power calculated value Δ P (t, Δ T) relevant with temperature variation on the array power voltage operation curve, if no temperature variation, Δ T=0, then voltage step-size in search Δ u _Pv(t, Δ T), realtime power calculated value Δ P (t, Δ T) is the controlled quentity controlled variable on pulse-length modulation (PWM) circuit and the stepping-up/stepping-down chopper circuit, by classic method control; If temperature variation is in time dynamically adjusted voltage step-size in search Δ u _Pv(t+1, Δ T) makes it to jump on the power voltage operation curve of temperature of living in, seeks the realtime power calculated value Δ P (t, Δ T) relevant with this temperature variation, thereby realizes the control to photovoltaic power generation array MPPT maximum power point tracking (MPPT); Said formula is:

Δu ₀(t，ΔT)＝KΔu _pv(t-1，ΔT)(1-aΔT)(1+bΔT) (1)

In the formula (1), Δ u ₀(t, Δ T) is the increment of the equivalent open-circuit voltage of the t real-time data acquisition and calculation that photovoltaic array is relevant with temperature increment Δ T constantly, and K is a stepping-up/stepping-down chopper circuit dutycycle adjustment coefficient, Δ u _Pv(t-1, Δ T) is the photovoltaic array Equivalent DC voltage increment relevant with temperature increment Δ T of the real-time data acquisition and calculation of previous moment, and Δ T is t-1 to t temperature increment constantly, and a, b are temperature varying coefficient: a=0.0025/ ℃, b=0.5/ ℃;

ΔI _sc(t，ΔT)＝ΔI _sc(t-1)(1+aΔT) (2)

In the formula (2), Δ I _Sc(t, Δ T) is the equivalent short-circuit current increment of the t real-time data acquisition and calculation that photovoltaic array is relevant with temperature increment Δ T constantly, Δ I _Sc(t-1, Δ T) is the photovoltaic array equivalence short-circuit current increment of the previous moment real-time data acquisition and calculation relevant with temperature increment Δ T;

$\mathrm{\Δ}{I}_{\mathrm{pv}}(t,\mathrm{\ΔT})=\mathrm{\Δ}{I}_{\mathrm{sc}}(t,\mathrm{\ΔT})\{1-[\exp \left(\frac{\mathrm{\Δ}{u}_{\mathrm{pv}}(t-1,\mathrm{\ΔT})}{\mathrm{\Δ}{u}_0(t-1,\mathrm{\ΔT})}\right)-1\left]\right\}---\left(3\right)$

In the formula (3), Δ I _Pv(t, Δ T) is the Equivalent DC current increment relevant with temperature increment Δ T that t moment photovoltaic array sends, Δ u ₀(t-1, Δ T) is the increment of the equivalent open-circuit voltage of the t-1 real-time data acquisition and calculation that photovoltaic array is relevant with temperature increment Δ T constantly,

Δu _pv(t，ΔT)＝ΔI _pv(t，ΔT)Z _th(t，ΔT) (4)

In the formula (4), Δ u _Pv(t, Δ T) is the Equivalent DC voltage increment relevant with temperature increment Δ T that t moment photovoltaic array sends, Z _Th(t, Δ T) is t X constantly, 2 equivalent Dai Weinan impedances relevant with temperature increment Δ T to the electric system side of Y;

ΔP(t，ΔT)＝Δu _pv(t，ΔT)ΔI _pv(t，ΔT) (5)

In the formula (5), Δ P (t, Δ T) is the t realtime power calculated value relevant with temperature increment Δ T of photovoltaic array constantly.

A kind of maximum power point of photovoltaic power generation system of realizing is followed the tracks of (MPPT) device based on the control method of temperature variation, and it comprises real time environment temperature detection information auxiliary circuit 1, main control circuit 2, dynamic electric voltage step-size in search MPPT auxiliary control circuit 3, pulse-length modulation (PWM) driving circuit 4, DC current voltage detecting circuit 5, direct current detects and filtering circuit 6, DC-DC stepping-up/stepping-down chopper circuit 7 and dynamic control variable comparator circuit 8; Real time environment temperature detection information auxiliary circuit 1 is connected with dynamic electric voltage step-size in search MPPT auxiliary control circuit 3 with main control circuit 2, and detected ambient temperature information is real-time transmitted to main control circuit 2 and dynamic electric voltage step-size in search MPPT auxiliary control circuit 3; Main control circuit 2 and dynamic control variable comparator circuit 8; Dynamic electric voltage step-size in search MPPT auxiliary control circuit 3; DC current voltage detecting and filtering circuit 6; PWM driving circuit 4; Real time environment temperature detection information auxiliary circuit 1 is connected with the inversion grid connection device; With the ambient temperature information that transmits according to real time environment temperature detection information auxiliary circuit 1; The Real Time Observation ambient temperature information is sought best power voltage operation curve and the optimum dynamically MPPT voltage step-size in search of search; Form dynamic power voltage operation curve in real time; Its result is fed back to dynamic electric voltage step-size in search MPPT auxiliary control circuit 3 and DC current voltage detecting and filtering circuit 6; When temperature change value Δ T is zero, send trigger pip to PWM driving circuit 4; Dynamic electric voltage step-size in search MPPT auxiliary control circuit 3 links to each other with main control circuit 2, will calculate the Equivalent DC voltage u relevant with temperature in real time _Pv(t, Δ T), Equivalent DC electric current I _PvWhether (t, Δ T) and Equivalent DC power P (t, Δ T) need be adjusted above-mentioned formula (1) and formula (2) to confirm this moment, and with main control circuit 2 exchange messages; Dynamic electric voltage step-size in search MPPT auxiliary control circuit 3 also links to each other with dynamic control variable comparator circuit 8, with as a Δ T, when b Δ T is non-vanishing, to dynamic control variable comparator circuit 8 output equivalent DC voltage u _Pv(t, Δ T) and Equivalent DC power P (t, Δ T) and the temperature independent Equivalent DC voltage u that exports with main control circuit 2 _Pv(t) and temperature independent Equivalent DC power P (t) compare and the output Equivalent DC voltage increment Δ u relevant with temperature _Pv(t, Δ T) and the Equivalent DC power increment Δ P (t, Δ T) relevant with temperature are the controlled quentity controlled variable of PWM driving circuit 4 and DC-DC stepping-up/stepping-down chopper circuit 7; PWM driving circuit 4 is with dynamically control variable comparator circuit 8, DC-DC stepping-up/stepping-down chopper circuit 7 are connected with main control circuit 2; Receive the operation information of dynamic electric voltage step-size in search MPPT auxiliary control circuit 3 and main control circuit 2 in real time, send trigger pulse and remove to control the switch in the DC-DC stepping-up/stepping-down chopper circuit 7; DC current voltage detecting circuit 5 is connected with photovoltaic array with dynamic electric voltage step-size in search MPPT auxiliary control circuit 3, DC-DC stepping-up/stepping-down chopper circuit 7, detects the equivalent open-circuit voltage u of photovoltaic array in real time ₀(t) and equivalent short-circuit current I _Sc(t), and with it send into dynamic electric voltage step-size in search MPPT auxiliary control circuit 3; DC current voltage detecting and filtering circuit 6 are connected with DC-DC stepping-up/stepping-down chopper circuit 7, main control circuit 2 and inversion grid connection device, detect the current/voltage value in real time according to the requirement of parallel network reverse, and filter harmonic wave according to the standard-required of harmonic wave; DC-DC stepping-up/stepping-down chopper circuit 7 is connected with DC current voltage detecting and filtering circuit 6 with PWM driving circuit 4, dynamically the photovoltaic array output voltage is changed into the DC current voltage that needs before the parallel network reverse; Dynamically control variable comparator circuit 8 is connected with main control circuit 2 with dynamic electric voltage step-size in search MPPT auxiliary control circuit 3, PWM driving circuit 4.

Because the present invention has adopted technique scheme, solved existing control method and existed slow, no temperature tracking of tracking speed and the low technical matters of whole output efficiency.Compared with prior art, the present invention have whole output efficiency high, can control advantage such as maximum power point of photovoltaic power generation system tracking based on temperature variation.

Description of drawings

Fig. 1 is the power voltage operation curve figure of photovoltaic array normal temperature difference during sunshine;

Fig. 2 is the power voltage operation curve characteristic pattern of photovoltaic generation power when change in voltage;

Power voltage operation curve figure when Fig. 3 is photovoltaic array different temperatures at identical sunshine;

Fig. 4 is a solar energy photovoltaic array equivalent circuit diagram;

Fig. 5 is based on the frame principle figure of the MPPT control device of temperature variation;

Fig. 6 is based on the flow chart of the MPPT control method of temperature variation.

Embodiment

Maximum power point of photovoltaic power generation system in the present embodiment is followed the tracks of (MPPT) control method based on temperature variation, and it is according to formula, and calculating photovoltaic power generation array is voltage step-size in search Δ u based on the voltage increment on the power voltage curve of temperature variation _Pv(t, Δ T) is voltage step-size in search Δ u through the voltage increment of controlling on this array power voltage curve _Pv(t, Δ T) dynamically seeks the realtime power calculated value Δ P (t, Δ T) relevant with temperature variation on the array power voltage operation curve, if no temperature variation, Δ T=0, then voltage step-size in search Δ u _Pv(t, Δ T), realtime power calculated value Δ P (t, Δ T) is the controlled quentity controlled variable on pulse-length modulation (PWM) circuit and the stepping-up/stepping-down chopper circuit, by classic method control; If temperature variation is in time dynamically adjusted voltage step-size in search Δ u _Pv(t+1, Δ T) makes it to jump on the power voltage operation curve of temperature of living in, seeks the realtime power calculated value Δ P (t, Δ T) relevant with this temperature variation, thereby realizes the control to photovoltaic power generation array MPPT maximum power point tracking (MPPT); Said formula is:

Δu ₀(t，ΔT)＝KΔu _pv(t-1，ΔT)(1-aΔT)(1+bΔT) (1)

In the formula (1), Δ u ₀(t, Δ T) is the increment of the equivalent open-circuit voltage of the t real-time data acquisition and calculation that photovoltaic array is relevant with temperature increment Δ T constantly, and K is a stepping-up/stepping-down chopper circuit dutycycle adjustment coefficient, Δ u _Pv(t-1, Δ T) is the photovoltaic array Equivalent DC voltage increment relevant with temperature increment Δ T of the real-time data acquisition and calculation of previous moment, and Δ T is t-1 to t temperature increment constantly, and a, b are temperature varying coefficient: a=0.0025/ ℃, b=0.5/ ℃;

ΔI _sc(t，ΔT)＝ΔI _sc(t-1)(1+aΔT) (2)

In the formula (2), Δ I _SC(t, Δ T) is the equivalent short-circuit current increment of the t real-time data acquisition and calculation that photovoltaic array is relevant with temperature increment Δ T constantly, Δ I _Sc(t-1, Δ T) is the photovoltaic array equivalence short-circuit current increment of the previous moment real-time data acquisition and calculation relevant with temperature increment Δ T;

$\mathrm{\Δ}{I}_{\mathrm{pv}}(t,\mathrm{\ΔT})=\mathrm{\Δ}{I}_{\mathrm{sc}}(t,\mathrm{\ΔT})\{1-[\exp \left(\frac{\mathrm{\Δ}{u}_{\mathrm{pv}}(t-1,\mathrm{\ΔT})}{\mathrm{\Δ}{u}_0(t-1,\mathrm{\ΔT})}\right)-1\left]\right\}---\left(3\right)$

In the formula (3), Δ I _Pv(t, Δ T) is the Equivalent DC current increment relevant with temperature increment Δ T that t moment photovoltaic array sends, Δ u ₀(t-1, Δ T) is the increment of the equivalent open-circuit voltage of the t-1 real-time data acquisition and calculation that photovoltaic array is relevant with temperature increment Δ T constantly,

Δu _pv(t，ΔT)＝ΔI _pv(t，ΔT)Z _th(t，ΔT) (4)

In the formula (4), Δ u _Pv(t, Δ T) is the Equivalent DC voltage increment relevant with temperature increment Δ T that t moment photovoltaic array sends, Z _Th(t, Δ T) is t X constantly, 2 equivalent Dai Weinan impedances relevant with temperature increment Δ T to the electric system side of Y;

ΔP(t，ΔT)＝Δu _pv(t，ΔT)ΔI _pv(t，ΔT) (5)

In the formula (5), Δ P (t, Δ T) is the t realtime power calculated value relevant with temperature increment Δ T of photovoltaic array constantly.

As shown in Figure 5; A kind of maximum power point of photovoltaic power generation system of realizing is followed the tracks of (MPPT) device based on the control method of temperature variation, and it comprises real time environment temperature detection information auxiliary circuit 1, main control circuit 2, dynamic electric voltage step-length MPPT auxiliary control circuit 3, pulse-length modulation (PWM) driving circuit 4, DC current voltage detecting circuit 5, direct current detects and filtering circuit 6, DC-DC stepping-up/stepping-down chopper circuit 7 and dynamic control variable comparator circuit 8; Real time environment temperature detection information auxiliary circuit 1 is connected with dynamic electric voltage step-length MPPT auxiliary control circuit 3 with main control circuit 2, and detected ambient temperature information is real-time transmitted to main control circuit 2 and dynamic electric voltage step-length MPPT auxiliary control circuit 3; Main control circuit 2 and dynamic control variable comparator circuit 8; Dynamic electric voltage step-length MPPT auxiliary control circuit 3; DC current voltage detecting and filtering circuit 6; PWM driving circuit 4; Real time environment temperature detection information auxiliary circuit 1 is connected with the inversion grid connection device; With the ambient temperature information that transmits according to real time environment temperature detection information auxiliary circuit 1; The Real Time Observation ambient temperature information is sought best power voltage operation curve and the optimum dynamically MPPT voltage step-size in search of search; Form dynamic power voltage operation curve in real time; Its result is fed back to dynamic electric voltage step-length MPPT auxiliary control circuit 3 and DC current voltage detecting and filtering circuit 6; When temperature change value Δ T is zero, send trigger pip to PWM driving circuit 4; Dynamic electric voltage step-length MPPT auxiliary control circuit 3 links to each other with main control circuit 2, will calculate the Equivalent DC voltage u relevant with temperature in real time _Pv(t, Δ T), Equivalent DC electric current I _PvWhether (t, Δ T) and Equivalent DC power P (t, Δ T) need be adjusted above-mentioned formula (1) and formula (2) to confirm this moment, and with main control circuit 2 exchange messages; Dynamic electric voltage step-length MPPT auxiliary control circuit 3 also links to each other with dynamic control variable comparator circuit 8, with when a Δ T and b Δ T are non-vanishing, to dynamic control variable comparator circuit 8 output equivalent DC voltage u _Pv(t, Δ T) and Equivalent DC power P (t, Δ T) and the temperature independent Equivalent DC voltage u that exports with main control circuit 2 _Pv(t) and temperature independent Equivalent DC power P (t) compare and the output Equivalent DC voltage increment Δ u relevant with temperature _Pv(t, Δ T) and the Equivalent DC power increment Δ P (t, Δ T) relevant with temperature are the controlled quentity controlled variable of PWM driving circuit 4 and DC-DC stepping-up/stepping-down chopper circuit 7; PWM driving circuit 4 is with dynamically control variable comparator circuit 8, DC-DC stepping-up/stepping-down chopper circuit 7 are connected with main control circuit 2; Receive the operation information of dynamic electric voltage step-length MPPT auxiliary control circuit 3 and main control circuit 2 in real time, send trigger pulse and remove to control the switch in the DC-DC stepping-up/stepping-down chopper circuit 7; DC current voltage detecting circuit 5 is connected with photovoltaic array with dynamic electric voltage step-length MPPT auxiliary control circuit 3, DC-DC stepping-up/stepping-down chopper circuit 7, detects the equivalent open-circuit voltage u of photovoltaic array in real time ₀(t) and equivalent short-circuit current I _Sc(t), and with it send into dynamic electric voltage step-length MPPT auxiliary control circuit 3; DC current voltage detecting and filtering circuit 6 are connected with DC-DC stepping-up/stepping-down chopper circuit 7, main control circuit 2 and inversion grid connection device, detect the current/voltage value in real time according to the requirement of parallel network reverse, and filter harmonic wave according to the standard-required of harmonic wave; DC-DC stepping-up/stepping-down chopper circuit 7 is connected with DC current voltage detecting and filtering circuit 6 with PWM driving circuit 4, dynamically the photovoltaic array output voltage is changed into the DC current voltage that needs before the parallel network reverse; Dynamically control variable comparator circuit 8 is connected with main control circuit 2 with dynamic electric voltage step-length MPPT auxiliary control circuit 3, PWM driving circuit 4.

The function of real time environment temperature detection information auxiliary circuit 1 is that detected ambient temperature information is real-time transmitted to main control circuit 2 and dynamic electric voltage step-length MPPT auxiliary control circuit 2, and these two circuit are applied to the temperature information that obtains in the MPPT control method based on temperature variation; Related variable is dynamically revised, and dynamically sought new power voltage operation curve, and then on new curve, seek new MPPT.

The function of main control circuit 2 is to seek best power voltage operation curve and the optimum dynamically MPPT voltage step size of search according to disturbance observation and ambient temperature information; Form dynamic power voltage operation curve in real time; Its result is fed back to dynamic electric voltage step-length MPPT auxiliary control circuit 3 and DC current voltage detecting and filtering circuit 6; When temperature change value Δ T is zero, send trigger pip to PWM driving circuit 4.Detect the preceding DC current voltage signal of parallel network reverse in real time, and carry out Filtering Processing.The direct current equivalent voltage u that main control circuit 2 is temperature independent according to detected information _Pv(t), the temperature independent direct current equivalent voltage u of previous time period _Pv(t-1), temperature independent direct current equivalent current I _Pv(t), the temperature independent direct current equivalent current I of previous time period _Pv(t-1), with this tittle come real-time rated output t constantly with temperature independent performance number P (t) and P (t-1) of the t-1 moment, i.e. power difference DELTA P (t)=P (t)-P (t-1), voltage difference Δ u _Pv(t)=u _Pv(t)-u _Pv(t-1), if this moment, the working point operated on the power voltage operation curve of temperature-resistantization, then like temperature among Fig. 3 according to shown in 25 ℃ of curves, the power difference DELTA P (t) that calculates of main control circuit 2 then, temperature independent Equivalent DC voltage increment Δ u _Pv(t) be the controlled quentity controlled variable of PWM driving circuit 4 and DC-DC stepping-up/stepping-down chopper circuit 7.If the working point operates on the power voltage operation curve of temperature variation; As shown in Figure 3; This moment at t+1 constantly; Dynamically adjust voltage step size rapidly; And with the working point from temperature be 25 ℃ of curves to jump to temperature be on 50 ℃ of curves, the voltage power information of transmitted power voltage operation curve in real time simultaneously.At this moment, main control circuit 2 is also in real time with temperature independent direct current equivalent voltage u _Pv(t), the t constantly information of power P (t) sends into dynamic control variable comparator circuit 8, the relevant Equivalent DC voltage u with temperature that calculates in real time with dynamic electric voltage step-length MPPT auxiliary control circuit 3 _Pv(t, Δ T), the Equivalent DC power P relevant with temperature (t, Δ T) compares, and obtains the Equivalent DC voltage increment Δ u relevant with temperature _Pv(t, Δ T), the Equivalent DC power increment Δ P (t, Δ T) relevant with temperature is the controlled quentity controlled variable of PWM driving circuit 4 and DC-DC stepping-up/stepping-down chopper circuit 7.

The function of dynamic electric voltage step-length MPPT auxiliary control circuit 3 is to calculate the Equivalent DC voltage u relevant with temperature in real time _Pv(t, Δ T), the Equivalent DC electric current I _Pv(t; Δ T); Equivalent DC power P (t; Δ T); To confirm whether need adjust this moment to formula among the present invention (1) and formula (2); And with main control circuit 2 exchange messages, as a Δ T, when b Δ T is non-vanishing, to the dynamic control variable comparator circuit 8 outputs Equivalent DC voltage u relevant with temperature _Pv(t, Δ T), Equivalent DC power P relevant (t, Δ T) and the temperature independent Equivalent DC voltage u that exports with main control circuit 2 with temperature _Pv(t), t power P (t) constantly compares, and the output Equivalent DC voltage increment Δ u relevant with temperature _Pv(t, Δ T), the Equivalent DC power increment Δ P (t, Δ T) relevant with temperature is the controlled quentity controlled variable of PWM driving circuit 4 and DC-DC stepping-up/stepping-down chopper circuit 7.

PWM driving circuit 4 receives the operation information of dynamic electric voltage step-length MPPT auxiliary control circuit 3 and main control circuit 2 in real time, sends trigger pulse and removes to operate the switch in the DC-DC stepping-up/stepping-down chopper circuit 7.

DC current voltage detecting circuit 5 detects the equivalent open-circuit voltage u of photovoltaic array in real time ₀(t) and equivalent short-circuit current I _Sc(t), and with it send into dynamic electric voltage step-length MPPT auxiliary control circuit 3.

The function of DC current voltage detecting and filtering circuit 6 is, detects the current/voltage value in real time according to the requirement of parallel network reverse, and filters relevant harmonic wave according to the GB and the international standard of harmonic wave.

DC-DC stepping-up/stepping-down chopper circuit 7, its function are dynamically the photovoltaic array output voltage to be changed into the DC current voltage that needs before the parallel network reverse.

Fig. 6 is the flow chart that the present invention is based on the MPPT control method of temperature variation.As shown in the figure; In the middle of the solar energy photovoltaic array, gather short-circuit current and open-circuit voltage values in real time; And input is normal and the i-v curve and the parameter limit value of temperature variation; Whether with temperature have relation, with temperature the irrelevant operation curve that all will form power and voltage is in real time arranged if constantly surveying this current/voltage.And initial voltage step-size in search is set, on the power operation curve, search MPPT, and the direction of definite power.If any link of total system breaks down, then system is out of service.If system's operation is normal, whether so next Rule of judgment is for operating on the equilibrium temperature curve.At this moment; If temperature does not change; Then search MPPT by the power voltage curve of single power peak characteristic; By etc. the voltage step size method confirm the mode of buck copped wave and obtain the voltage and the power increment of control corresponding switch; These increments are used to the dutycycle of compute switch; And be used as controlled quentity controlled variable and remove to drive pwm control circuit, locked up to MPPT.If in the middle of the process of searching MPPT, the voltage step-size in search is then adjusted in temperature generation cataclysm dynamically, jumps to the power voltage operation curve of another temperature rapidly from a kind of power voltage operation curve of temperature.And on new temperature power voltage operation curve continuous dynamically adjustment voltage step size; Confirm the mode of buck copped wave by dynamic voltage step size method and obtain the voltage and the power increment of control corresponding switch; These increments are used to the dutycycle of compute switch; And be used as controlled quentity controlled variable and remove to drive pwm control circuit, locked up to MPPT.Follow the tracks of (MPPT) control method in the hope of realizing optimum maximum power point of photovoltaic power generation system based on temperature variation.

Do further detailed description in the face of control method of the present invention down.

As shown in Figure 1: when different sunshine of normal temperature, when environment temperature is 25 ℃, and day illumination is from 400W/m ²To 1000W/m ²During variation, the photovoltaic array maximum power point (mpp) presents rapid variation, but output voltage values is stabilized in 440V.Promptly corresponding to different amplitudes at sunshine, the maximum power point on each bar power voltage operation curve changes, but the relative voltage value stabilization.In such cases, every power voltage operation curve all has the characteristic of single power peak.This situation can characterize its homogeny with Fig. 2.

As shown in Figure 2, transverse axis u _PvBe the VD of solar energy photovoltaic array, P is the output power of solar energy photovoltaic array.If Δ u among the figure _PvBe the voltage step-size in search, and Δ P is corresponding power increment.Among Fig. 2, P ₁, P ₂Be corresponding power peak P _MaxThe corresponding Δ u in left side _Pv2 performance numbers, P ₃, P ₄Be corresponding power peak P _MaxThe corresponding Δ u in right side _Pv2 performance numbers.Traditional method that does not stress the account temperature variation all is at P ₁, P ₂Differentiate its power positive and negative to the derivative of voltage during variation.If P ₂＞P ₁, Δ P/ Δ u _Pv＞0 explanation power search point is just by P _MaxThe left side approach to MPPT.Otherwise, if P ₃＜P ₄, Δ P/ Δ u _Pv＜0, illustrate that power search point is just by P _MaxThe right side approach to MPPT.And if as Δ P/ Δ u _Pv=0 o'clock, P then _MaxPoint is locked.Its corresponding photovoltaic array electrical voltage point is maximum power point P _MaxVoltage.

As shown in Figure 3, at identical sunshine during different temperatures, not only photovoltaic array voltage takes place sharply to change, and significant change also takes place MPPT maximum power point tracking (MPPT).Its main performance characteristic is that the power voltage operation curve is all moving up and down at great-jump-forward of MPPT.If still approach MPPT with the traditional voltage step-size in search obviously is invalid.So the present invention propose following when the temperature variation dynamic change voltage step size calculate the control method of MPPT.

In fact, from Fig. 3, can draw when temperature changes, bigger variation takes place in the output voltage of photovoltaic power generation array, thereby causes the variation that MPPT is ordered.DC voltage booster circuit in The conventional PV system (BOOST) circuit application is more, if when temperature sharply raises, the MPPT point moves to the low-voltage direction fast.If untimely adjustment step-length, booster circuit (BOOST) circuit can obviously lose efficacy, only if the starting potential value is established very lowly, but system effectiveness is reduced greatly, also can make system's not only complicacy but also understable when gating pulse width modulated (PWM) dutycycle.The present invention uses stepping-up/stepping-down chopper circuit (BUCKBOOST), and the voltage-regulation scope of straight-flow system is increased.Through the voltage increment on the control system power voltage curve is the voltage step-size in search, dynamically seeks the system power voltage operation curve variation relation relevant with temperature.Thereby the adjustment traditional control method, and find a kind of method removal search to follow the tracks of (MPPT) control method based on temperature variation based on maximum power point of photovoltaic power generation system through the dynamic control voltage step-length.

As shown in Figure 3, this sets of curves is the system voltage power operation curve curve relevant with temperature.Longitudinal axis P (W) is the power shaft that power constantly changes with temperature, transverse axis u _Pv(V) be the temperature variant output voltage axle of photovoltaic array.If it is on 25 ℃ the power voltage curve that system operates in temperature at this moment, and the voltage step-size in search of this moment is Δ u _Pv(t-1, Δ T), corresponding power increment Δ P (t-1, Δ T), the voltage step size of search naturally in next time period is Δ u _Pv(t, Δ T) is with previous moment Δ u _Pv(t-1, Δ T) equates, corresponding power increment Δ P (t, Δ T), if this moment, temperature did not change, then above-mentioned in Δ T in all subscript variables be zero.If no temperature variation, then Δ u _Pv(t, Δ T), Δ P (t, Δ T) is the controlled quentity controlled variable on pwm circuit and the stepping-up/stepping-down chopper circuit, and promptly as shown in Figure 2, available traditional method is asked for Δ u _Pv(t), Δ P (t) (at this moment, Δ T is zero).But if this moment because of temperature variation, it is on 50 ℃ the curve time that the voltage power operation curve jumps to temperature of living in, like the method for still the continuing to use voltage step-size in search of etc.ing, and to be operated in temperature be that then obviously search was lost efficacy on 25 ℃ the curve, and cause that mistake controls.So must dynamically adjust Δ u this moment rapidly _PvThe step-length of (t+1, Δ T) makes it to jump to temperature and is on 50 ℃ the power voltage operation curve, on this curve, searches for MPPT.

Can get according to Fig. 1 photovoltaic array power voltage operation curve:

$S\underset{\mathrm{VP}\→0}{\underset{{\mathrm{Vu}}_{\mathrm{pv}}\→0}{=}}N\frac{\mathrm{dP}}{{\mathrm{du}}_{\mathrm{pv}}}---\left(6\right)$

In the formula (6), S is slope or the derivative on the power voltage operation curve, and N is a constant, Vu _PvBe the voltage disturbance step-length on the power voltage operation curve, VP is corresponding to Vu _PvPower step size, dP works as Vu _Pv, the power limit value of photovoltaic array when VP goes to zero, i.e. differential value.Du _PvBe to work as Vu _Pv, the output voltage ultimate value of solar energy photovoltaic array when VP goes to zero, i.e. differential value.

Solar energy photovoltaic array equivalent electrical circuit by among Fig. 4 can know that the power that the solar energy photovoltaic array sends is:

P _pv＝I _pvu _pv (7)

In the formula (7), I _PvBe the Equivalent DC electric current that photovoltaic array sends, u _PvBe the Equivalent DC voltage that photovoltaic array sends, P _PvBe the Equivalent DC power that photovoltaic array sends.

$I_{\mathrm{pv}}=I_{\mathrm{sc}}\{1-[\exp \left(\frac{u_{\mathrm{pv}}}{u_0}\right)-1\left]\right\}---\left(8\right)$

In the formula (8), I _ScBe the short-circuit current that photovoltaic array sends, u ₀It is the open-circuit voltage of photovoltaic array.

MPPT computing formula when above formula is traditional not account temperature variation.When temperature variation, the dynamic change step size increments in the time of must introducing the account temperature variation removes to control pwm circuit and stepping-up/stepping-down chopper circuit, and its formula is:

Δu ₀(t，ΔT)＝KΔu _pv(t-1，ΔT)(1-aΔT)(1+bΔT) (1)

In the formula (1), Δ u ₀(t, Δ T) is the increment of the equivalent open-circuit voltage of real-time data acquisition and calculation relevant with temperature increment Δ T in the t time chart 4, and K is a stepping-up/stepping-down chopper circuit dutycycle adjustment coefficient, Δ u _Pv(t-1, Δ T) is the photovoltaic array Equivalent DC voltage increment relevant with temperature increment Δ T of the real-time data acquisition and calculation of previous moment, and Δ T is t-1 to t temperature increment constantly, and a, b are temperature varying coefficient: a=0.0025/ ℃ .b=0.5/ ℃

ΔI _sc(t，ΔT)＝ΔI _sc(t-1)(1+aΔT) (2)

In the formula (2), Δ I _Sc(t) be the equivalent short-circuit current increment of real-time data acquisition and calculation relevant in the t time chart 4, Δ I with temperature increment Δ T _Sc(t-1, Δ T) is the photovoltaic array equivalence short-circuit current increment of the previous moment real-time data acquisition and calculation relevant with temperature increment Δ T.

$\mathrm{\Δ}{I}_{\mathrm{pv}}(t,\mathrm{\ΔT})=\mathrm{\Δ}{I}_{\mathrm{sc}}(t,\mathrm{\ΔT})\{1-[\exp \left(\frac{\mathrm{\Δ}{u}_{\mathrm{pv}}(t-1,\mathrm{\ΔT})}{\mathrm{\Δ}{u}_0(t-1,\mathrm{\ΔT})}\right)-1\left]\right\}---\left(3\right)$

In the formula (3), Δ I _Pv(t, Δ T) is the Equivalent DC current increment relevant with temperature increment Δ T that t moment photovoltaic array sends.Δ u ₀(t-1, Δ T) is the increment of the equivalent open-circuit voltage of real-time data acquisition and calculation relevant with temperature increment Δ T in the t-1 time chart 4,

Δu _pv(t，ΔT)＝ΔI _pv(t，ΔT)Z _th(t，ΔT) (4)

In the formula (4), Δ u _Pv(t, Δ T) is the Equivalent DC voltage increment relevant with temperature increment Δ T that t moment photovoltaic array sends, Z _Th(t, Δ T) be in the t time chart 4 from X, 2 of Y see the equivalent Dai Weinan impedance relevant with temperature increment Δ T to the electric system side.

ΔP(t，ΔT)＝Δu _pv(t，ΔT)ΔI _pv(t，ΔT) (5)

In the formula (5), Δ P (t, Δ T) is the t realtime power calculated value relevant with temperature increment Δ T of photovoltaic array constantly.

When ambient temperature does not change, a Δ T=0 in the above-mentioned formula, b Δ T=0.

So all formula emphasis are applicable to when temperature changes among the present invention, the maximum power point of photovoltaic array calculates, and simultaneously, also can calculate maximum power value calculating under the difference situation at sunshine when constant temperature.

As shown in Figure 4, the represented I of dotted line among the figure _ScEquivalent short-circuit current when being the photovoltaic array short circuit.Electric capacity of voltage regulation when capacitor C is the photovoltaic array open circuit among Fig. 4 is connected with the photovoltaic array parallel, and the upside of capacitor C links to each other with the DC-DC stepping-up/stepping-down chopper circuit, and the downside of capacitor C links to each other with common port Y point.u ₀It is the photovoltaic array open-circuit voltage at capacitor C two ends.The left side of DC-DC stepping-up/stepping-down chopper circuit links to each other with the upper end of capacitor C, and the lower end of DC-DC stepping-up/stepping-down chopper circuit links to each other with common point Y, and the right-hand member of DC-DC stepping-up/stepping-down chopper circuit links to each other with parallel network reverse point X.I _PvBe the photovoltaic Equivalent DC electric current that provides to electric system behind the photovoltaic array process DC-DC stepping-up/stepping-down chopper circuit, u _PvBe the photovoltaic Equivalent DC voltage that provides to electric system behind the photovoltaic array process DC-DC buck chopper.Z _ThBe from X, 2 equivalent Dai Weinan impedances of Y to the electric system side.

Claims (2)

1. a maximum power point of photovoltaic power generation system is followed the tracks of (MPPT) control method based on temperature variation, and it is characterized in that: according to formula, calculating photovoltaic power generation array is voltage step-size in search Δ u based on the voltage increment on the power voltage curve of temperature variation _Pv(t, Δ T) is voltage step-size in search Δ u through the voltage increment of controlling on this array power voltage curve _Pv(t, Δ T) dynamically seeks the realtime power calculated value Δ P (t, Δ T) relevant with temperature variation on the array power voltage operation curve, if no temperature variation, Δ T=0, then voltage step-size in search Δ u _Pv(t, Δ T), realtime power calculated value Δ P (t, Δ T) is the controlled quentity controlled variable on pulse-length modulation (PWM) circuit and the stepping-up/stepping-down chopper circuit, by classic method control; If temperature variation is in time dynamically adjusted voltage step-size in search Δ u _Pv(t+1, Δ T) makes it to jump on the power voltage operation curve of temperature of living in, seeks the realtime power calculated value Δ P (t, Δ T) relevant with this temperature variation, thereby realizes the control to photovoltaic power generation array MPPT maximum power point tracking (MPPT); Said formula is:

Δu ₀(t，ΔT)＝KΔu _pv(t-1，ΔT)(1-aΔT)(1+bΔT) (1)

In the formula (1), Δ u ₀(t, Δ T) is the increment of the equivalent open-circuit voltage of the t real-time data acquisition and calculation that photovoltaic array is relevant with temperature increment Δ T constantly, and K is a stepping-up/stepping-down chopper circuit dutycycle adjustment coefficient, Δ u _Pv(t-1, Δ T) is the photovoltaic array Equivalent DC voltage increment relevant with temperature increment Δ T of the real-time data acquisition and calculation of previous moment, and Δ T is t-1 to t temperature increment constantly, and a, b are temperature varying coefficient: a=0.0025/ ℃, b=0.5/C;

ΔI _sc(t，ΔT)＝ΔI _sc(t-1)(1+aΔT) (2)

In the formula (2), Δ I _Sc(t, Δ T) is the equivalent short-circuit current increment of the t real-time data acquisition and calculation that photovoltaic array is relevant with temperature increment Δ T constantly, Δ I _Sc(t-1, Δ T) is the photovoltaic array equivalence short-circuit current increment of the previous moment real-time data acquisition and calculation relevant with temperature increment Δ T;

$\mathrm{\Δ}{I}_{\mathrm{pv}}(t,\mathrm{\ΔT})=\mathrm{\Δ}{I}_{\mathrm{sc}}(t,\mathrm{\ΔT})\{1-[\exp \left(\frac{\mathrm{\Δ}{u}_{\mathrm{pv}}(t-1,\mathrm{\ΔT})}{\mathrm{\Δ}{u}_0(t-1,\mathrm{\ΔT})}\right)-1\left]\right\}---\left(3\right)$

In the formula (3), Δ I _Pv(t, Δ T) is the Equivalent DC current increment relevant with temperature increment Δ T that t moment photovoltaic array sends, Δ u ₀(t-1, Δ T) is the increment of the equivalent open-circuit voltage of the t-1 real-time data acquisition and calculation that photovoltaic array is relevant with temperature increment Δ T constantly,

Δu _pv(t，ΔT)＝ΔI _pv(t，ΔT)Z _th(t，ΔT) (4)

In the formula (4), Δ u _Pv(t, Δ T) is the Equivalent DC voltage increment relevant with temperature increment Δ T that t moment photovoltaic array sends, Z _Th(t, Δ T) is t X constantly, 2 equivalent Dai Weinan impedances relevant with temperature increment Δ T to the electric system side of Y;

ΔP(t，ΔT)＝Δu _pv(t，ΔT)ΔI _pv(t，ΔT) (5)

In the formula (5), Δ P (t, Δ T) is the t realtime power calculated value relevant with temperature increment Δ T of photovoltaic array constantly.

2. the described maximum power point of photovoltaic power generation system of realization claim 1 is followed the tracks of (MPPT) device based on the control method of temperature variation, it is characterized in that: it comprises real time environment temperature detection information auxiliary circuit 1, main control circuit 2, dynamic electric voltage step-size in search MPPT auxiliary control circuit 3, pulse-length modulation (PWM) driving circuit 4, DC current voltage detecting circuit 5, direct current detects and filtering circuit 6, DC-DC stepping-up/stepping-down chopper circuit 7 and dynamic control variable comparator circuit 8; Real time environment temperature detection information auxiliary circuit 1 is connected with dynamic electric voltage step-size in search MPPT auxiliary control circuit 3 with main control circuit 2, and detected ambient temperature information is real-time transmitted to main control circuit 2 and dynamic electric voltage step-size in search MPPT auxiliary control circuit 3; Main control circuit 2 and dynamic control variable comparator circuit 8; Dynamic electric voltage step-size in search MPPT auxiliary control circuit 3; DC current voltage detecting and filtering circuit 6; PWM driving circuit 4; Real time environment temperature detection information auxiliary circuit 1 is connected with the inversion grid connection device; With the ambient temperature information that transmits according to real time environment temperature detection information auxiliary circuit 1; The Real Time Observation ambient temperature information is sought best power voltage operation curve and the optimum dynamically MPPT voltage step-size in search of search; Form dynamic power voltage operation curve in real time; Its result is fed back to dynamic electric voltage step-size in search MPPT auxiliary control circuit 3 and DC current voltage detecting and filtering circuit 6; When temperature change value Δ T is zero, send trigger pip to PWM driving circuit 4; Dynamic electric voltage step-size in search MPPT auxiliary control circuit 3 links to each other with main control circuit 2, will calculate the Equivalent DC voltage u relevant with temperature in real time _Pv(t, Δ T), Equivalent DC electric current I _PvWhether (t, Δ T) and Equivalent DC power P (t, Δ T) need be adjusted formula in the claim 1 (1) and formula (2) to confirm this moment, and with main control circuit 2 exchange messages; Dynamic electric voltage step-size in search MPPT auxiliary control circuit 3 also links to each other with dynamic control variable comparator circuit 8, with when a Δ T and b Δ T are non-vanishing, to dynamic control variable comparator circuit 8 output equivalent DC voltage u _Pv(t, Δ T) and Equivalent DC power P (t, Δ T) and the temperature independent Equivalent DC voltage u that exports with main control circuit 2 _Pv(t) and temperature independent Equivalent DC power P (t) compare and the output Equivalent DC voltage increment Δ u relevant with temperature _Pv(t, Δ T) and the Equivalent DC power increment Δ P (t, Δ T) relevant with temperature are the controlled quentity controlled variable of PWM driving circuit 4 and DC-DC stepping-up/stepping-down chopper circuit 7; PWM driving circuit 4 is with dynamically control variable comparator circuit 8, DC-DC stepping-up/stepping-down chopper circuit 7 are connected with main control circuit 2; Receive the operation information of dynamic electric voltage step-size in search MPPT auxiliary control circuit 3 and main control circuit 2 in real time, send trigger pulse and remove to control the switch in the DC-DC stepping-up/stepping-down chopper circuit 7; DC current voltage detecting circuit 5 is connected with photovoltaic array with dynamic electric voltage step-size in search MPPT auxiliary control circuit 3, DC-DC stepping-up/stepping-down chopper circuit 7, detects the equivalent open-circuit voltage u of photovoltaic array in real time ₀(t) and equivalent short-circuit current I _Sc(t), and with it send into dynamic electric voltage step-size in search MPPT auxiliary control circuit 3; DC current voltage detecting and filtering circuit 6 are connected with DC-DC stepping-up/stepping-down chopper circuit 7, main control circuit 2 and inversion grid connection device, detect the current/voltage value in real time according to the requirement of parallel network reverse, and filter harmonic wave according to the standard-required of harmonic wave; DC-DC stepping-up/stepping-down chopper circuit 7 is connected with DC current voltage detecting and filtering circuit 6 with PWM driving circuit 4, dynamically the photovoltaic array output voltage is changed into the DC current voltage that needs before the parallel network reverse; Dynamically control variable comparator circuit 8 is connected with main control circuit 2 with dynamic electric voltage step-size in search MPPT auxiliary control circuit 3, PWM driving circuit 4.

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