CN204536976U - A kind of photovoltaic control device realizing novel maximal power tracing algorithm - Google Patents

Abstract

A kind of photovoltaic control device realizing novel maximal power tracing algorithm, comprise photovoltaic array, DC Module, MPPT controller, three-phase inversion module, inverter control unit and filtration module, described photovoltaic array is by DC Module and three-phase inversion model calling, three-phase inversion module is connected with inverter control unit, and DC Module is connected with inverter control unit by MPPT controller; This realizes the photovoltaic control device of novel maximal power tracing algorithm, utilizes maximum power tracking method, and advantage calculates fast, accurately can supply the reference voltage of maximum power point of photovoltaic array by Quick, thus reduce power loss.What propose realizes photovoltaic parallel in system by d-q axle under control synchronization rotating coordinate system and gains merit and the method for idle uneoupled control, improves the conversion efficiency of photovoltaic parallel in system, indirectly improves the economic benefit of system, simultaneously adjustable systems power factor.This device has good dynamic steady-state behaviour, and system has very strong stability.

Description

A kind of photovoltaic control device realizing novel maximal power tracing algorithm

Technical field

The utility model belongs to generation of electricity by new energy technology, parallel network power generation technical field in photovoltaic generation, especially a kind of photovoltaic control device realizing novel maximal power tracing algorithm.

Background technology

In photovoltaic generating system, the utilization factor of photovoltaic cell except outside the Pass having with the bulk properties of photovoltaic cell, also by environment for use as the impact of the factors such as irradiance, load and temperature.Under different external condition, photovoltaic cell may operate at difference and on unique maximum power point (Maximum Power Point, MPP).For photovoltaic generating system, the optimum duty of photovoltaic cell should be sought, with to greatest extent by light energy conversion for electric energy.The technology that the maximum power output utilizing control method to realize photovoltaic cell runs is exactly maximal power tracing technology.

In theory, according to circuit theory; When the output impedance of photovoltaic cell is equal with loaded impedance, the output power of photovoltaic cell is maximum, and in fact the MPPT process of photovoltaic cell is exactly the process that photovoltaic cell output impedance and loaded impedance equivalence are matched.Because the output impedance of photovoltaic cell is by the impact of environmental factor, if realize the real-time adjustment to loaded impedance by control method, and make it follow the tracks of the output impedance of photovoltaic cell, the maximal power tracing that just can realize photovoltaic cell controls.

Maximum power tracking method the most frequently used at present comprises constant voltage process, disturbance observation and conductance increment method.Photovoltaic cell output voltage control certain certain voltage near its maximum power point is sentenced and is made photovoltaic cell obtain approximate maximum power output by constant voltage process, this method is simple and quick, but because it have ignored the impact of temperature and light according to Strength Changes, the error that constant voltage process follows the trail of maximum power point is very large, will cause power loss very greatly during environmental factor change.

Disturbance observation, by the output voltage of disturbance photovoltaic cell, is then observed the change of the output power from photovoltaic cells, is continuously changed disturbance voltage direction according to the trend of changed power, make photovoltaic cell finally work in maximum power point.When reference voltage increases, if photovoltaic array output power increases, then continue to increase reference voltage, otherwise then change perturbation direction; When reducing reference voltage, photovoltaic array output power increases, then continue to reduce reference voltage, otherwise then change perturbation direction, its shortcoming be perturbation direction always in continuous change, thus cause some power losses.

The rule that conductance increment method changes from the output power from photovoltaic cells with output voltage rate of change, derives relation between the conductance of system works point when maximum power point and conductance rate of change, and then proposes corresponding MPPT algorithm.Conductance increment method is according to photovoltaic cell dP/dU variation characteristic, a maximum power point is only there is when light intensity is certain, and different at maximum power point both sides dP/dU symbol, and at maximum power point place dP/dU=0, by the quantitative test to dP/dU, obtain corresponding maximum power point.The method has good dynamic property in the fast-changing situation of intensity of illumination, and its shortcoming needs sensor accuracy higher, and needs longer computing time, thus also can cause power loss.

There is various problems in above three kinds of maximum power tracking methods, and photovoltaic parallel in system has high requirements for the work efficiency of system, for this reason, need to propose to design novel maximum power tracking method, to meet photovoltaic parallel in system for the precision of maximum power tracking method and rate request.

Utility model content

The utility model aims to provide a kind of photovoltaic grid-connected device that can realize novel maximal power tracing scheme.The defect of existing maximal power tracing scheme precision and underspeed can be overcome, fully improve the efficiency of photovoltaic parallel in system, reduce power loss.By the design of photovoltaic grid-connected device hardware, it is the photovoltaic control device realizing novel maximal power tracing algorithm that novel maximal power tracing control program provides support.

For achieving the above object, the utility model provides following technical scheme: a kind of photovoltaic control device realizing novel maximal power tracing algorithm, comprise photovoltaic array, DC Module, MPPT controller, three-phase inversion module, inverter control unit and filtration module, described photovoltaic array is by DC Module and three-phase inversion model calling, three-phase inversion module is connected with inverter control unit, and DC Module is connected with inverter control unit by MPPT controller, described MPPT controller comprises DC voltage detection module, direct current detection module, MPPT control module, d. c. voltage signal output module and PI controller module, described DC voltage detection module is all connected with photovoltaic array by DC Module with direct current detection module, MPPT control module and DC voltage detection module and direct current detection model calling, this MPPT control module is connected with inverter module by PI controller module, and PI controller module is connected with DC voltage detection module, described inverter control unit comprises three-phase current detection module, detecting voltage by three phase module, three-phase voltage Clark conversion module, park conversion module, d shaft current PI control module, q shaft current PI control module and SVPWM control module, described three-phase current detection module and detecting voltage by three phase module are all by filtration module and three-phase inversion model calling, wherein three-phase current detection module is connected with park conversion module, this park conversion module comprises two-phase stationary voltages park and changes module and electric current park change module, electric current park changes module and three-phase current detection model calling, described detecting voltage by three phase module changes model calling by Clark conversion module and two-phase stationary voltages park, described park conversion module is connected with SVPWM control module respectively by d shaft current PI control module, q shaft current PI control module, this SVPWM control module and three-phase inversion model calling.

As further scheme of the present utility model: described three-phase inversion module is connected with electrical network by filtration module.

As further scheme of the present utility model: the DC master row series winding diode in described DC Module, arranges electric capacity in DC master row.

As further scheme of the present utility model: described q shaft current PI control module and power factor controlling model calling.

Compared with prior art, the beneficial effects of the utility model are: this realizes the photovoltaic control device of novel maximal power tracing algorithm, utilizes maximum power tracking method, and advantage calculates fast, accurately can supply the reference voltage of maximum power point of photovoltaic array by Quick, thus reduce power loss.What propose realizes photovoltaic parallel in system by d-q axle under control synchronization rotating coordinate system and gains merit and the method for idle uneoupled control, improves the conversion efficiency of photovoltaic parallel in system, indirectly improves the economic benefit of system, simultaneously adjustable systems power factor.This device has good dynamic steady-state behaviour, and grid-connected current is humorous involves percent harmonic distortion completely in IEEE 929-2000 critical field, and system has very strong stability.

Accompanying drawing explanation

Fig. 1 is function structure chart of the present utility model;

Relation principle figure between static three phase coordinate systems that Fig. 2 adopts for the utility model and synchronous rotating frame;

Fig. 3 is improved maximal power tracing algorithm flow chart by the utility model adopts;

Fig. 4 is maximal power tracing control loop and d shaft current control loop structured flowchart;

Fig. 5 power factor is the q shaft current control loop structured flowchart of 1.

Embodiment

Below in conjunction with the accompanying drawing in the utility model embodiment, be clearly and completely described the technical scheme in the utility model embodiment, obviously, described embodiment is only the utility model part embodiment, instead of whole embodiments.Based on the embodiment in the utility model, those of ordinary skill in the art are not making the every other embodiment obtained under creative work prerequisite, all belong to the scope of the utility model protection.

Refer to Fig. 1-5, in the utility model embodiment, a kind of photovoltaic control device realizing novel maximal power tracing algorithm, comprise photovoltaic array, DC Module, MPPT controller, three-phase inversion module, inverter control unit and filtration module, described photovoltaic array is by DC Module and three-phase inversion model calling, three-phase inversion module is connected with electrical network by filtration module, described three-phase inversion module is connected with inverter control unit, and DC Module is connected with inverter control unit by MPPT controller; DC master row series winding diode in described DC Module, effectively prevents electric current from pouring in down a chimney damage photovoltaic array, arranges electric capacity, mainly strobe in DC master row.

Described MPPT controller comprises DC voltage detection module, direct current detection module, MPPT control module, d. c. voltage signal output module and PI controller module, described DC voltage detection module is all connected with photovoltaic array by DC Module with direct current detection module, MPPT control module and DC voltage detection module and direct current detection model calling, this MPPT control module is connected with inverter module by PI controller module, and PI controller module is connected with DC voltage detection module; Wherein photovoltaic cell output voltage, the current signal of MPPT control algolithm module unidirectional reception DC voltage detection module and direct current detection module institute one-way transmission, process through MPPT control module, export d. c. voltage signal output module, deliver to inverter module through PI controller module; Wherein MPPT control module adopts novel maximum power control technology.

Described inverter control unit comprises three-phase current detection module, detecting voltage by three phase module, three-phase voltage Clark conversion module, park conversion module, d shaft current PI control module, q shaft current PI control module, power factor controlling module and SVPWM control module, described three-phase current detection module and detecting voltage by three phase module are all by filtration module and three-phase inversion model calling, wherein three-phase current detection module is connected with park conversion module, this park conversion module comprises two-phase stationary voltages park and changes module and electric current park change module, electric current park changes module and three-phase current detection model calling, described detecting voltage by three phase module changes model calling by Clark conversion module and two-phase stationary voltages park, described park conversion module is connected with SVPWM control module respectively by d shaft current PI control module, q shaft current PI control module, this SVPWM control module and three-phase inversion model calling, described q shaft current PI control module and power factor controlling model calling, wherein, three-phase current detection module and detecting voltage by three phase module detect the three-phase current and three-phase voltage that three-phase inversion module exports respectively, wherein, three-phase voltage changes module two step through Clark conversion module and two-phase stationary voltages park and is transformed into two-phase synchronizing voltage, and three-phase current changes module one step through electric current park and is converted into two-phase synchronizing current.

Described d shaft current PI control module adopts loop control theory (see Fig. 4), by controlling output current id control inverter active power.Its specific works principle: the reference voltage that the UMPP in Fig. 4 provides photovoltaic array DC master row to export by hereafter proposed maximal power tracing algorithm.It is the input of outer voltage PI controller Cdv (s) that the DC master row voltage U dc of actual measurement deducts the error that UMPP formed.

C _dv(s)＝K _I/s+K _p

In formula: KI and KP determines by experience, emulation or test; K is constant value, and its value size is grid-connected first-harmonic rated current peak value, and its effect carries out standardization to inverter output current; The d axle that Cdv (s) controller exports as inverter output is gained merit reference current, and its value variation range is 0-1.With under line voltage synchronous rotating frame, convert the alternating current applying equation under measured three-phase static coordinate system to d-q axle similar DC current and control, it is 0 that steady-state error is controlled.

Fig. 4 shows photovoltaic DC-to-AC converter and exports d shaft current control loop.The error that the DC current id of three-phase AC current after rotation change also standardization that the reference current that Control of Voltage outer shroud provides deducts actual measurement is formed is the input of synchronous PI controller Cdi (s), it exports is form space vector pulse width modulation (space vector pulse width modulation, SVPWM) signal.

Q shaft current PI control module adopts loop control theory (see Fig. 5), by controlling output current iq, controls photovoltaic parallel in system power factor.Its principle of work: Fig. 5 shows the q shaft current control loop structured flowchart that power factor is 1, and wherein the output of Cqi (s) controller forms SVPWM signal, q shaft current control loop and d shaft current control loop optimum configurations completely the same.

Principle of work of the present utility model: this device needs to measure photovoltaic array output voltage Udc, output current Idc; Inverter output current iA, iB, iC; Line voltage ugA, ugB, ugC.Utilize formula (1) that measured line voltage is carried out Clark conversion, then fixed-point algorithm application arctan function is adopted to try to achieve electrical network vector voltage anglec of rotation θ, θ angle is the angle under synchronous rotary d-q coordinate system between q axle with electrical network A phase axle, as shown in Figure 2.

$\left[\begin{array}{c}{u}_{\mathrm{\α}}\\ u_{\mathrm{\β}}\\ u_0\end{array}\right]=\left[\begin{array}{ccc}2/3& -1/3& -1/3\\ 0& 1/\sqrt{3}& -1/\sqrt{3}\\ 1/3& 1/3& 1/3\end{array}\right]\left[\begin{array}{c}{u}_{\mathrm{gA}}\\ u_{\mathrm{gB}}\\ u_{\mathrm{gC}}\end{array}\right]---\left(1\right)$

Under static three-phase A-B-C coordinate system, three-phase grid state equation can be described by formula (2):

$\frac{d}{\mathrm{dt}}\left[\begin{array}{c}{i}_A\\ i_B\\ i_C\end{array}\right]=\frac{1}{L}\left[\begin{array}{c}{u}_A\\ u_B\\ u_C\end{array}\right]-\frac{1}{L}\left[\begin{array}{c}{u}_{\mathrm{gA}}\\ u_{\mathrm{gB}}\\ u_{\mathrm{gC}}\end{array}\right]---\left(2\right)$

In formula: [i _ai _bi _c] ^tfor inverter current vector; [u _au _bu _c] ^tfor inverter exports phase voltage vector; [u _gAu _gBu _gC] ^tfor electrical network phase voltage vector; L is every phase reactor inductance, ignores inductance internal resistance.

In order to realize high performance grid-connected Current Control, the equation of state (2) based on rest frame A-B-C need be transformed to the equation of state (3) under synchronous d-q coordinate system.Of acs all is like this transformed to DC quantity, is conducive to pi regulator and carries out closed-loop control to grid-connected current.

$\frac{d}{\mathrm{dt}}\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]=\left[\begin{array}{cc}0& \mathrm{\ω}\\ -\mathrm{\ω}& 0\end{array}\right]\left[\begin{array}{c}{i}_d\\ i_q\end{array}\right]+\frac{1}{L}\left[\begin{array}{c}{u}_d\\ u_q\end{array}\right]-\frac{1}{L}\left[\begin{array}{c}{u}_{\mathrm{gd}}\\ u_{\mathrm{gq}}\end{array}\right]---\left(3\right)$

In formula: subscript d, q represent d-q axle parameter amount; ω is electrical network fundamental voltage angular velocity of rotation.Matrix for coordinate transform is Park transformation matrix and inverse-transform matrix, shown in (4), (5):

$\left[\begin{array}{c}{X}_d\\ X_q\end{array}\right]=\frac{2}{3}\left[\begin{array}{ccc}\sin \mathrm{\θ}& \sin (\mathrm{\θ}-\frac{2}{3}\mathrm{\π})& \sin (\mathrm{\θ}+\frac{2}{3}\mathrm{\π})\\ \cos \mathrm{\θ}& \cos (\mathrm{\θ}-\frac{2}{3}\mathrm{\π})& \cos (\mathrm{\θ}+\frac{2}{3}\mathrm{\π})\end{array}\right]\left[\begin{array}{c}{X}_A\\ X_B\\ X_C\end{array}\right]---\left(4\right)$

$\left[\begin{array}{c}{X}_A\\ X_B\\ X_C\end{array}\right]=\left[\begin{array}{cc}\sin \mathrm{\θ}& \cos \mathrm{\θ}\\ \sin (\mathrm{\θ}-\frac{2}{3}\mathrm{\π})& \cos (\mathrm{\θ}-\frac{2}{3}\mathrm{\π})\\ \sin (\mathrm{\θ}+\frac{2}{3}\mathrm{\π})& \cos (\mathrm{\θ}+\frac{2}{3}\mathrm{\π})\end{array}\right]\left[\begin{array}{c}{X}_d\\ X_q\end{array}\right]---\left(5\right)$

In formula, X represents corresponding electric current, voltage.

According to the relation of trigonometric function, Fig. 2 shows three-phase power grid voltage Vector Rotation angle θ and the relation between static A-B-C coordinate system and synchronous rotary d-q coordinate system.

Under synchronous rotary d-q coordinate system, three-phase photovoltaic grid-connected system is transported to the meritorious and idle of electrical network and is

$\left\{\begin{array}{c}P=\frac{3}{2}(u_{\mathrm{gd}}{i}_d+u_{\mathrm{gq}}{i}_q)\\ Q=\frac{3}{2}(u_{\mathrm{gd}}{i}_q+u_{\mathrm{gq}}{i}_d)\end{array}\right.---\left(6\right)$

Suppose that three-phase power grid voltage is not containing the ideal sinusoidal amount of any harmonic wave, three-phase voltage available formula (7) under A-B-C rest frame represents:

$\left\{\begin{array}{c}{u}_{\mathrm{gA}}=U\sin \left(\mathrm{\θ}\right)\\ u_{\mathrm{gB}}=U\sin (\mathrm{\θ}-2/3\mathrm{\π})\\ u_{\mathrm{gC}}=U\sin (\mathrm{\θ}+2/3\mathrm{\π})\end{array}\right.---\left(7\right)$

In formula: U is the peak value of every phase line voltage.Formula (7) is carried out Park and is converted to obtain formula (8) by applying equation (4)

$\left\{\begin{array}{c}{u}_{\mathrm{gd}}=U\\ u_{\mathrm{gq}}=0\end{array}\right.---\left(8\right)$

Photovoltaic grid-connected device outputs to the meritorious of electrical network and regulates according to d shaft current, is transported to the idle of electrical network and regulates according to q shaft current.Therefore under synchronous rotating frame, gaining merit of electrical network and idle uneoupled control is transported to by controlling just to realize photovoltaic parallel in system respectively to d-q shaft current; And regulate photovoltaic array output voltage to realize maximum power point of photovoltaic array by control d shaft current to follow the tracks of, improve the conversion efficiency of photovoltaic parallel in system, indirectly improve the economic benefit of system, control q shaft current is 0 simultaneously, photovoltaic array can be made to export grid-connected current by voltage source inverter completely identical with line voltage phase place, power factor is 1.

The novel maximal power tracing algorithm that the utility model adopts, is characterized in that it is made up of (see Fig. 3) following steps:

(1) arrange the initial value of photovoltaic array operating voltage, its value size is about the open circuit voltage 0.8 times of photovoltaic array.

(2) measure the value of current time photovoltaic array output voltage Un, In, and calculating its product, to try to achieve current time photovoltaic array output power be Pn.

(3) Pn trying to achieve the current time further and difference DELTA P of previous moment photovoltaic array output power Pp preserved, and the Un trying to achieve current time photovoltaic array is Δ U with the difference of the previous moment photovoltaic array output voltage Up preserved.

(5) utilize fixed point Newton-Raphson algorithm to try to achieve Δ P/ Δ U differential value fast, then sign bit Sign value is set according to Δ P/ Δ U.

For the method to set up of step (5) sign bit Sign, be made up of following step:

1., during Δ P/ Δ U>0, arranging sign bit Sign value is 1, increases the la tension de reference Uref est of photovoltaic array work according to the step-length set (Step);

2. when this differential value is less than 0, arranging sign bit Sign value is-1, reduces the la tension de reference Uref est of photovoltaic array work by the step-length preset;

3. when this differential value equals 0, arranging sign bit Sign value is 0, keeps the la tension de reference Uref est of photovoltaic array work constant.

To those skilled in the art, obvious the utility model is not limited to the details of above-mentioned one exemplary embodiment, and when not deviating from spirit of the present utility model or essential characteristic, can realize the utility model in other specific forms.Therefore, no matter from which point, all should embodiment be regarded as exemplary, and be nonrestrictive, scope of the present utility model is limited by claims instead of above-mentioned explanation, and all changes be therefore intended in the implication of the equivalency by dropping on claim and scope are included in the utility model.Any Reference numeral in claim should be considered as the claim involved by limiting.

In addition, be to be understood that, although this instructions is described according to embodiment, but not each embodiment only comprises an independently technical scheme, this narrating mode of instructions is only for clarity sake, those skilled in the art should by instructions integrally, and the technical scheme in each embodiment also through appropriately combined, can form other embodiments that it will be appreciated by those skilled in the art that.

Claims (4)

1. one kind realizes the photovoltaic control device of novel maximal power tracing algorithm, comprise photovoltaic array, DC Module, MPPT controller, three-phase inversion module, inverter control unit and filtration module, it is characterized in that, described photovoltaic array is by DC Module and three-phase inversion model calling, three-phase inversion module is connected with inverter control unit, and DC Module is connected with inverter control unit by MPPT controller, described MPPT controller comprises DC voltage detection module, direct current detection module, MPPT control module, d. c. voltage signal output module and PI controller module, described DC voltage detection module is all connected with photovoltaic array by DC Module with direct current detection module, MPPT control module and DC voltage detection module and direct current detection model calling, this MPPT control module is connected with inverter module by PI controller module, and PI controller module is connected with DC voltage detection module, described inverter control unit comprises three-phase current detection module, detecting voltage by three phase module, three-phase voltage Clark conversion module, park conversion module, d shaft current PI control module, q shaft current PI control module and SVPWM control module, described three-phase current detection module and detecting voltage by three phase module are all by filtration module and three-phase inversion model calling, wherein three-phase current detection module is connected with park conversion module, this park conversion module comprises two-phase stationary voltages park and changes module and electric current park change module, electric current park changes module and three-phase current detection model calling, described detecting voltage by three phase module changes model calling by Clark conversion module and two-phase stationary voltages park, described park conversion module is connected with SVPWM control module respectively by d shaft current PI control module, q shaft current PI control module, this SVPWM control module and three-phase inversion model calling.

2. a kind of photovoltaic control device realizing novel maximal power tracing algorithm according to claim 1, it is characterized in that, described three-phase inversion module is connected with electrical network by filtration module.

3. a kind of photovoltaic control device realizing novel maximal power tracing algorithm according to claim 1, is characterized in that, the DC master row series winding diode in described DC Module, arranges electric capacity in DC master row.

4. a kind of photovoltaic control device realizing novel maximal power tracing algorithm according to claim 1, is characterized in that, described q shaft current PI control module and power factor controlling model calling.