CN104571256B - A kind of photo-voltaic power supply extremum search method considering illumination variation - Google Patents

Abstract

The present invention relates to a kind of photo-voltaic power supply extremum search system and method considering illumination variation, including: photovoltaic panel, PWM signal generator, pi regulator, sensor, Self Adaptive Control operator module, current disturbing operator module, variable step disturbing operator module；Therefore the present invention is by considering the photo-voltaic power supply extremum search system of illumination variation, arranges Self Adaptive Control operator module, current disturbing operator module and variable step disturbing operator module；Achieve the observation perturbation motion method to the classical magnitude of current to improve, add photo-voltaic power supply current disturbing quantitative change step-length operator module and photovoltaic operating point Self Adaptive Control operator gel, achieve the adjustment operating point that photo-voltaic power supply under different illumination conditions is quick, stable, to follow the trail of peak power.The simple in construction of the present invention, easy to operate, preferably solve traditional disturbance observation and there is the problem oscillated around at maximum power point, affect the technical problem of the stability of a system.

Description

A kind of photo-voltaic power supply extremum search method considering illumination variation

Technical field

The invention belongs to the test of power system real-timedigital simulation, micro-capacitance sensor technical field, particularly relate to a kind of photo-voltaic power supply extremum search system and method considering illumination variation.

Background technology

At present, in order to maximally utilize solar energy, photovoltaic generating system maximum power point tracking to be introduced technology (MPPT), make the power output of photovoltaic array maximize.Photovoltaic array can be regarded as one group of dc source.Owing to solar cell has non-linear behavior, when intensity of illumination and variation of ambient temperature, its maximum power point can move change.So, the research of maximum power point of photovoltaic array has using value.Tradition disturbance observational technique based on voltage passes through constantly to change operating point and measure power output to find maximum power point to be conventional MPPT algorithm.But traditional disturbance observation has the problem oscillated around at maximum power point, affects the stability of system.

Summary of the invention

The present invention solves that traditional disturbance observation has the problem oscillated around at maximum power point, affect the stability of a system technical problem and provide a kind of simple in construction, easy to install, improve the photo-voltaic power supply extremum search system and method for consideration illumination variation of operating efficiency.

The present invention solves that technical problem is adopted the technical scheme that present in known technology:

A kind of photo-voltaic power supply extremum search method considering illumination variation of the embodiment of the present invention, the photo-voltaic power supply extremum search method of this consideration illumination variation includes:

Step one, first initializes current disturbing amount Δ I (k), and wherein k is iterations, takes Δ I (k)=0.05Isc, and Isc is photovoltaic array short circuit current；

Step 2, measures current photovoltaic array exit potential V_pv(k), photovoltaic array outlet electric current I_pv(k) and Intensity of the sunlight S；

Step 3, calculates current photovoltaic array power output P_pv(k)=V_pv(k)×I_pv(k)；

Step 4, verifies current photovoltaic array outlet electric current I_pvK whether () meet service condition constraint, and constraints is as follows: 2I_MPP-I_sc≤I_pv(k)≤I_sc, wherein I_MPPFor the outlet electric current under peak power, if constraints meets, go to step five entrance current disturbing operators；If constraints is unsatisfactory for, go to step eight entrance Self Adaptive Control operators；

Step 5, current disturbing operator, based on classical disturbance observation；Finally give reference current I_ref=I_pv(k)+sign(I_pv(k)-I_pv(k-1))*sign(P_pv(k)-P_pv(k-1)) * Δ I (k), updates P simultaneously_pv(k-1)=P_pv(k)、I_pv(k-1)=I_pv(k)；

Step 6, variable step disturbing operator realizes dynamically regulation disturbance step-length, it is achieved reducing the effect of disturbance step-length near maximum power point, variable step regulated quantity isWherein make m₁+m₂=1, select according in Practical Project, use m₁=0.6, m₂=0.4, additionally M=sign (P_pv(k)-P_pv(k-1))+sign(P_pv(k-1)-P_pv(k-2))；

Step 7, updates Δ I (k)=Δ I_F, return step 2；

Step 8, Self Adaptive Control operator, according to the sudden change of Intensity of the sunlight, dynamically regulates disturbance step-length with reference to short circuit current method, increases disturbance step-length and quickly approaches maximum power point, improving extreme value and follow the trail of efficiency, reference current and adaptive step regulated quantity are the most specifically calculated as follows:

$\left\{\begin{array}{c}{I}_{\mathrm{ref}}=\frac{(1+k_{\mathrm{sc}})I_{\mathrm{sc}}(S_{\mathrm{nom}},T_{\mathrm{nom}})K_A}{{2S}_{\mathrm{nom}}}S\\ \mathrm{\Δ}{I}_C=\frac{(1-k_{\mathrm{sc}})I_{\mathrm{sc}}(S_{\mathrm{nom}},T_{\mathrm{nom}})K_A}{{\mathrm{NS}}_{\mathrm{nom}}}S\end{array}\right.,$

Wherein S_nom,T_nom,I_sc(S_nom,T_nom) be respectively the intensity of illumination under standard test condition, temperature and by determined by photovoltaic panel short circuit current function, K_AFor photovoltaic panel aging life-span correction factor, take empirical value 0.55, k_scShort circuit current method ratio is followed the trail of for photo-voltaic power supply extreme value Coefficient, takes 0.78～0.92, and mean value 0.85, S is current Intensity of the sunlight, and N is photovoltaic panel quantity in photovoltaic array；

Step 9, updates P_pv(k-1)=P_pv(k)、I_pv(k-1)=I_pv(k)、I_pv(k)=I_ref, Δ I (k)=Δ I_C, return step 2；

Step 10, as Δ P_pvWhen=0, then current photovoltaic array operates on new maximum power point, and calculation process terminates.

Another object of the present invention is to provide a kind of photo-voltaic power supply extremum search system considering illumination variation, the photo-voltaic power supply extremum search system of this consideration illumination variation includes: photovoltaic panel, PWM signal generator, pi regulator, sensor, Self Adaptive Control operator module, current disturbing operator module, variable step disturbing operator module；

The photovoltaic panel gathered for solar energy；

The PWM signal generator being connected with photovoltaic panel, regulates the voltage and current signal of photovoltaic panel output by adjusting pulse duty factor；

With PWM signal generator pi regulator even, i.e. proportional and integral controller, its effect is the steady-state error reducing whole control system；

It is connected with Self Adaptive Control operator module 5 and current disturbing operator module, for inputting Intensity of the sunlight, photovoltaic array exit potential and the sensor of photovoltaic array outlet electric current；

The Self Adaptive Control operator module being connected with pi regulator, disturbance step-length can be dynamically regulated with reference to short circuit current method, it is achieved that in the case of extraneous environmental change according to the sudden change of Intensity of the sunlight, increase disturbance step-length and quickly approach maximum power point, improve extreme value and follow the trail of efficiency；

The current disturbing operator module in curent change direction is found for current running current is applied disturbance quantity；

The variable step disturbing operator module being connected with current disturbing operator module and pi regulator, it is achieved that dynamically regulation current disturbing step-length, it is achieved that reduce the effect of disturbance step-length near maximum power point, thus inhibit maximum power point to oscillate around phenomenon.

The present invention can also use following technical measures:

In an embodiment of the present invention, photovoltaic panel is additionally provided with inductance, electric capacity, resistance, switch and IGCT.

Further, three sensors it are provided with.

The present invention has the advantage that with good effect: owing to the present invention is by considering the photo-voltaic power supply extremum search system of illumination variation, arrange Self Adaptive Control operator module, current disturbing operator module and variable step disturbing operator module；Achieve the observation perturbation motion method to the classical magnitude of current to improve, add photo-voltaic power supply current disturbing quantitative change step-length operator module and photovoltaic operating point Self Adaptive Control operator module, achieve the adjustment operating point that photo-voltaic power supply under different illumination conditions is quick, stable, to follow the trail of peak power.The simple in construction of the present invention, easy to operate, preferably solve traditional disturbance observation and there is the problem oscillated around at maximum power point, affect the technical problem of the stability of a system.

Accompanying drawing explanation

Fig. 1 is the photo-voltaic power supply extremum search system architecture schematic diagram of the consideration illumination variation that the embodiment of the present invention provides；

Fig. 2 is the workflow diagram of the photo-voltaic power supply extremum search method of the consideration illumination variation that the embodiment of the present invention provides；

Fig. 3 is the photo-voltaic power supply extremum search system contrast waveform diagram with conventional method of the consideration illumination variation that the embodiment of the present invention provides；

In figure: 1, photovoltaic panel；2, PWM signal generator；3, pi regulator；4, sensor；5, Self Adaptive Control operator module；6, current disturbing operator module；7, variable step disturbing operator module.

Detailed description of the invention

In order to make the purpose of the present invention, technical scheme and advantage clearer, below in conjunction with embodiment, the present invention is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.

Below in conjunction with the accompanying drawings and the application principle of the present invention is further described by specific embodiment.

Refer to Fig. 1 and Fig. 2:

As it is shown in figure 1, the photo-voltaic power supply extremum search system of the consideration illumination variation of the embodiment of the present invention mainly by: photovoltaic panel 1, PWM signal generator 2, pi regulator 3, sensor 4, Self Adaptive Control operator module 5, current disturbing operator module 6, variable step disturbing operator module 7 form；

The photovoltaic panel 1 gathered for solar energy；

The PWM signal generator 2 being connected with photovoltaic panel 1, regulates the voltage and current signal of photovoltaic panel output by adjusting pulse duty factor；

With PWM signal generator 2 pi regulator 3 even, i.e. proportional and integral controller, its effect is the steady-state error reducing whole control system；

It is connected with Self Adaptive Control operator module 5 and current disturbing operator module 6, for inputting Intensity of the sunlight, photovoltaic array exit potential and the sensor of photovoltaic array outlet electric current；

The Self Adaptive Control operator module 5 being connected with pi regulator 3, disturbance step-length can be dynamically regulated with reference to short circuit current method, it is achieved that in the case of extraneous environmental change according to the sudden change of Intensity of the sunlight, increase disturbance step-length and quickly approach maximum power point, improve extreme value and follow the trail of efficiency；

The current disturbing operator module 6 in curent change direction is found for current running current is applied disturbance quantity；

The variable step disturbing operator module 7 being connected with current disturbing operator module 6 and pi regulator 3, it is achieved that dynamically regulation current disturbing step-length, it is achieved that reduce the effect of disturbance step-length near maximum power point, thus inhibit maximum power point to oscillate around phenomenon.

Photovoltaic panel 1 is additionally provided with inductance, electric capacity, resistance, switch and IGCT；

It is provided with three sensors；

The operation principle of the present invention:

Fig. 1 provides the schematic diagram of the photovoltaic array extremum search system of the consideration illumination variation that the present invention proposes；Wherein Intensity of the sunlight, photovoltaic array exit potential v_pv, photovoltaic array outlet electric current i_pvIt it is the measurement amount (input quantity) of the present invention, differentiation according to service condition constraint, above-mentioned input signal is calculated reference signal by current disturbing operator module (CPA), variable step disturbing operator module (VPA) and Self Adaptive Control operator module (ACA), i.e. electric current I_ref, it is compared with photovoltaic outlet electric current, difference is adjusted by pi regulator, obtain duty cycle signals d, then realize photovoltaic array output voltage v by the off state of PWM signal generator control switching device_oControl so that it is operate in maximum power point.

Fig. 2 provides the flow chart of implementation method of the present invention；Specifically comprise the following steps that

Step one, first initializes current disturbing amount Δ I (k), and wherein k is iterations.Implementing desirable Δ I (k)=0.05Isc, Isc is photovoltaic array short circuit current, and this value can be found on photovoltaic panel nameplate；

Step 2, measures current photovoltaic array exit potential V_pv(k), photovoltaic array outlet electric current I_pv(k) and Intensity of the sunlight S；

Step 3, calculates current photovoltaic array power output P_pv(k)=V_pv(k)×I_pv(k)；

Step 4, verifies current photovoltaic array outlet electric current I_pvK whether () meet service condition constraint, and constraints is as follows: 2I_MPP-I_sc≤I_pv(k)≤I_sc, wherein I_MPPFor the outlet electric current under peak power dated on photovoltaic panel nameplate.If this constraints meets, go to step five entrance current disturbing operators；If this constraints is unsatisfactory for, go to step eight entrance Self Adaptive Control operators；

Step 5, current disturbing operator, based on classical disturbance observation, idiographic flow such as Fig. 2 dotted line shows；Finally give reference current I_ref=I_pv(k)+sign(I_pv(k)-I_pv(k-1))*sign(P_pv(k)-P_pv(k-1)) * Δ I (k), updates P simultaneously_pv(k-1)=P_pv(k)、I_pv(k-1)=I_pv(k)；

Step 6, variable step disturbing operator achieves dynamically regulation disturbance step-length, it is achieved that reduces the effect of disturbance step-length near maximum power point, thus inhibits maximum power point to oscillate around phenomenon；Variable step regulated quantity isWherein make m₁+m₂=1, can select according in Practical Project, it is proposed that use m₁=0.6, m₂=0.4, additionally M=sign (P_pv(k)-P_pv(k-1))+sign(P_pv(k-1)-P_pv(k-2))

Step 7, updates Δ I (k)=Δ I_F, return step 2；

Step 8, Self Adaptive Control operator, according to the sudden change of Intensity of the sunlight, dynamically regulates disturbance step-length with reference to short circuit current method, it is achieved that in the case of extraneous environmental change, increases disturbance step-length and quickly approaches maximum power point, improves extreme value and follows the trail of efficiency.Reference current and adaptive step regulated quantity are the most specifically calculated as follows:

$\left\{\begin{array}{c}{I}_{\mathrm{ref}}=\frac{(1+k_{\mathrm{sc}})I_{\mathrm{sc}}(S_{\mathrm{nom}},T_{\mathrm{nom}})K_A}{{2S}_{\mathrm{nom}}}S\\ \mathrm{\Δ}{I}_C=\frac{(1-k_{\mathrm{sc}})I_{\mathrm{sc}}(S_{\mathrm{nom}},T_{\mathrm{nom}})K_A}{{\mathrm{NS}}_{\mathrm{nom}}}S\end{array}\right.,$

Wherein S_nom,T_nom,I_sc(S_nom,T_nom) it is respectively intensity of illumination, temperature and photovoltaic panel short circuit current function determined by the two, the K under standard test condition_AFor photovoltaic panel aging life-span correction factor, typically take empirical value 0.55, k_scShort circuit current method ratio is followed the trail of for photo-voltaic power supply extreme value Coefficient, typically takes 0.78～0.92, and the present invention uses its mean value 0.85, and S is current Intensity of the sunlight (instantaneous value), and N is photovoltaic panel quantity in photovoltaic array；

Step 9, updates P_pv(k-1)=P_pv(k)、I_pv(k-1)=I_pv(k)、I_pv(k)=I_ref, Δ I (k)=Δ I_C, return step 2；

Step 10, as Δ P_pvWhen=0, then current photovoltaic array operates on new maximum power point, and calculation process terminates.

Use the simulation softwares such as RTDS, MATLAB, l-G simulation test carried out by the extremum search model building this patent proposition, present invention invention is contrasted with traditional observation method of perturbation, as shown in Figure 3, from result of the test, the method that the present invention proposes is superior to conventional method from calculating speed and stability.

The foregoing is only presently preferred embodiments of the present invention, not in order to limit the present invention, all any amendment, equivalent and improvement etc. made within the spirit and principles in the present invention, should be included within the scope of the present invention.

Claims (1)

1. the photo-voltaic power supply extremum search method considering illumination variation, it is characterised in that the photo-voltaic power supply extremum search method of this consideration illumination variation includes:

Step one, first initializes current disturbing amount Δ I (k), and wherein k is iterations, takes Δ I (k)=0.05Isc, and Isc is photovoltaic array short circuit current；

Step 2, measures current photovoltaic array exit potential V_pv(k), photovoltaic array outlet electric current I_pv(k) and Intensity of the sunlight S；

Step 3, calculates current photovoltaic array power output P_pv(k)=V_pv(k)×I_pv(k)；

Step 4, verifies current photovoltaic array outlet electric current I_pvK whether () meet is run constraints, and constraints is as follows: 2I_MPP-I_sc≤I_pv(k)≤I_sc, wherein I_MPPFor the outlet electric current under peak power, if constraints meets, go to step five entrance current disturbing operators；If constraints is unsatisfactory for, go to step eight entrance Self Adaptive Control operators；

Step 5, current disturbing operator, based on classical disturbance observation；Finally give reference current I_ref=I_pv(k)+sign(I_pv(k)-I_pv(k-1))*sign(P_pv(k)-P_pv(k-1)) * Δ I (k), updates P simultaneously_pv(k-1)=P_pv(k)、I_pv(k-1)=I_pv(k)；

Step 6, variable step disturbing operator realizes dynamically regulation disturbance step-length, it is achieved reducing the effect of disturbance step-length near maximum power point, variable step regulated quantity isWherein make m₁+m₂=1, select according in Practical Project, use m₁=0.6, m₂=0.4, additionally M=sign (P_pv(k)-P_pv(k-1))+sign(P_pv(k-1)-P_pv(k-2))；

Step 7, updates Δ I (k)=Δ I_F, return step 2；

Step 8, Self Adaptive Control operator, according to the sudden change of Intensity of the sunlight, dynamically regulates disturbance step-length with reference to short circuit current method, increases disturbance step-length and quickly approaches maximum power point, improving extreme value and follow the trail of efficiency, reference current and adaptive step regulated quantity are the most specifically calculated as follows:

Wherein S_nom,T_nom,I_sc(S_nom,T_nom) it is respectively the intensity of illumination under standard test condition, temperature and the photovoltaic panel short circuit current function determined by them, K_AFor photovoltaic panel aging life-span correction factor, take empirical value 0.55, k_scFollowing the trail of short circuit current method proportionality coefficient for photo-voltaic power supply extreme value, take 0.78～0.92, S is current Intensity of the sunlight, and N is photovoltaic panel quantity in photovoltaic array；

Step 9, updates P_pv(k-1)=P_pv(k)、I_pv(k-1)=I_pv(k)、I_pv(k)=I_ref, Δ I (k)=Δ I_C, return step 2；

Step 10, as Δ P_pvWhen=0, then current photovoltaic array operates on new maximum power point, and calculation process terminates.