CN106020326A - Rapid photovoltaic module maximum power tracking system and method - Google Patents

Abstract

The invention relates to the field of maximum power tracking, in particular to a rapid photovoltaic module maximum power tracking system and method. The maximum power tracking system comprises a voltage sensor, a current sensor, a switching device, a recursion average filtering module, a phase-locked amplifier, a divider and an integral regulator; the voltage sensor is connected with the recursion average filtering module and the phase-locked amplifier respectively, the recursion average filtering module and the phase-locked amplifier are connected with the divider respectively, and the divider is connected with the integral regulator which is connected with the switching device. According to the rapid photovoltaic module maximum power tracking system and method, photovoltaic module maximum power point tracking control can be well achieved when external environmental conditions are changed, oscillation of output power near the maximum power point can be effectively inhibited, the tracking speed is high, tracking is easy to achieve, and the generating efficiency of a photovoltaic module is improved.

Description

A kind of quickly photovoltaic module maximum power tracing system and method for tracing

Technical field

The present invention relates to maximum power tracing field, be specifically related to a kind of quickly photovoltaic module maximum power tracing system and Its method for tracing.

Background technology

MPPT maximum power point tracking (Maximum Power Point Tracking is called for short MPPT) system is a kind of by adjusting The duty of joint electrical module, enables photovoltaic panel to export the electrical system of more electric energy, it is possible to be sent out by solar panel The unidirectional current gone out is stored in accumulator effectively, can efficiently solve remote districts and tourist site that normal grid can not cover The life in district and commercial power, do not produce environmental pollution

Traditional photovoltaic module maximum power tracing method (such as disturbance observational method, conductance increment method etc.) needs in operating point Introduce disturbance quantity, can cause when environmental condition changes tracking error and near maximum power point output shake Swing.

Summary of the invention

The present invention provides a kind of quickly photovoltaic module maximum power tracing method, and solving existing traditional blackboard needs artificial wiping Wiping, the problem affecting teaching efficiency, concrete technical scheme is as follows:

A kind of quickly photovoltaic module maximum power tracing system, including voltage sensor, current sensor, switching device, The output electric current iPV of the frequency sampling photovoltaic module that described electric current, voltage sensor are the most certain and voltage uPV, described switch Device is controlled break-make by pwm pulse signal, makes photovoltaic module be operated in certain power points, also includes:

Recurrence average filtration module: be used for filtering input signal iPV and uPV medium-high frequency periodic disturbance component, retains letter DC component in numberWith

Lock-in amplifier: obtain input signal iPV and switching frequency component of degree n n amplitude diPV of uPV and duPV；

Divider: willDivided byObtain Gdc, diPV and obtain gdc divided by duPV；

Integral controller: eliminate the error of Gdc and gdc, is adaptively adjusted dutycycle d, produces pwm pulse signal and controls The on, off of switching device.

Described voltage sensor connects recurrence average filtration module and lock-in amplifier, described recurrence average filtering mould respectively Block and lock-in amplifier connect divider respectively, and described divider connects integral controller, described integral controller connecting valve Device.

Further, described recurrence average filtration module takes M sampled value and regards a round-robin queue as, and the length of queue is solid Being set to M, sample a new data every time and put into tail of the queue, and throw away data of original head of the queue, wave filter exports every time The arithmetic mean of instantaneous value of M data in data always current queue.

Further, the frequency that described integral controller produces pwm pulse signal is consistent with the switching frequency of switching device, And sample frequency is the multiple of switching frequency.

A kind of quickly photovoltaic module maximum power tracing method, comprises the steps:

1) voltage sensor and current sensor are respectively with output electric current iPV and the voltage of certain frequency sampled light photovoltaic assembly Signal is also reached recurrence average filtration module and lock-in amplifier by uPV；

2) recurrence average filtration module obtains the direct current component value of iPV and uPVWithAnd reach divider, phase-locked put Big device obtains switching frequency component of degree n n amplitude diPV and the duPV of iPV and uPV, and reaches divider；

3) divider willDivided byObtain Gdc, diPV and obtain gdc divided by duPV, and Gdc and gdc is reached integral adjustment Device,

4) integral controller eliminates the error of Gdc and gdc, is adaptively adjusted dutycycle d, produces pwm signal and controls to open Close the on, off of device, so that photovoltaic module works in maximum power point.

Further, described step 3) in integral controller can be replaced by pi regulator or PID regulator.

The present invention provides a kind of quickly photovoltaic module maximum power tracing system and tracking thereof, and this method is at extraneous ring Can well realize photovoltaic module maximum power point tracking when border condition changes, can effectively suppress in peak power The vibration of output near point, follows the trail of speed and soon and is easily achieved, improve the generating efficiency of photovoltaic module.

Accompanying drawing explanation

In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing In having technology to describe, the required accompanying drawing used is briefly described, it should be apparent that, the accompanying drawing in describing below is only this Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, it is also possible to Other accompanying drawing is obtained according to these accompanying drawings.

Fig. 1 is output power of photovoltaic module-voltage characteristic；

Fig. 2 is photovoltaic module maximum power tracing circuit based on boost changer；

Fig. 3 is that recurrence average filters (RAF) theory diagram；

Fig. 4 is lock-in amplifier (LIA) theory diagram；

Fig. 5 is maximum power tracing schematic diagram.

Detailed description of the invention

For making the purpose of the embodiment of the present invention, technical scheme and advantage clearer, below in the embodiment of the present invention Technical scheme is clearly and completely described, it is clear that described embodiment is a part of embodiment of the present invention rather than complete The embodiment in portion.Based on the embodiment in the present invention, those of ordinary skill in the art are not under making creative work premise The every other embodiment obtained, broadly falls into the scope of protection of the invention.

Embodiment 1:

Fig. 1 is output power of photovoltaic module-voltage response, from output characteristics, at photovoltaic module at maximum work Conductance at rate point is zero.

$\frac{{\mathrm{dp}}_{PV}}{{\mathrm{du}}_{PV}}=\frac{d}{{\mathrm{du}}_{PV}}(i_{PV}\×u_{PV})=0---\left(1\right)$

Above formula is arranged

$\frac{i_{PV}}{u_{PV}}=-\frac{{\mathrm{di}}_{PV}}{{\mathrm{du}}_{PV}}---\left(2\right)$

i_PV/u_PVDefine the load admittance G of DC point_dc,-di_PV/du_PVDefine small-signal admittance g_dc, therefore, When photovoltaic module is operated at maximum power point, have

G_dc=g_dc (3)

If when ambient conditions changes, can constantly make formula (3) meet, then photovoltaic module works in peak power Point.

Photovoltaic module maximum power tracing circuit based on boost changer as shown in Figure 2, due to switching device VT's HF switch works, and causes photovoltaic module output voltage u_PVWith output electric current i_PVIn in addition to DC component, also comprise high frequency Component (frequency be switching frequency and the most for several times).If using and obtaining wherein DC component someway, G can be obtained_dc；If energy Obtain the amplitude of wherein switching frequency component of degree n n, g can be obtained_dc, then use closed loop control to make G_dc=g_dc, accounted for accordingly Empty ratio d, produces pwm signal and controls the conducting shutoff of switching device VT, photovoltaic module can be made to work in maximum power point.

Recurrence average filtering (Recursive Average Filtering, RAF)

Implementation method: taking M sampled value continuously and regard a round-robin queue as, the length of queue is fixed as M, samples every time One new data puts into tail of the queue, and throws away a data (first in first out) of original head of the queue, the number that wave filter exports every time Arithmetic mean of instantaneous value according to M data in always current queue.The method is particularly well-suited to filter signal medium-high frequency and periodically disturbs Dynamic component, the DC component in stick signal.

Its mathematic(al) representation that realize is presented herein below

$y\left(k\right)=\frac{1}{M}\underset{m=0}{\overset{M-1}{\Σ}}x(k-m)---\left(4\right)$

In formula, x represents that input signal, y represent that, through the filtered output signal of RAF, k represents current time sampled value, M Represent the number of continuous sampling.

The switching frequency making switching device is f_s, switch periods is T_s；Sample frequency is f_c, the sampling period is T_c。

$M=\frac{f_c}{f_s}---\left(5\right)$

When value shown in M modus ponens (5), RAF can filter the high frequency period opening, turning off introducing due to switching device Property disturbance component.

Fig. 3 is that recurrence average filtering (RAF) realizes schematic diagram, and in figure, x represents input signal to obtain it straight after RAF filters Flow component.

Lock-in amplifier (Lock-in amplifier, LIA)

Lock-in amplifier can obtain the amplitude of a certain characteristic frequency in input signal (parameter incoming frequency) signal, and defeated Enter other frequency contents in signal and output can not be constituted any impact.

Make x (t)=n (t)+Asin (2 π f_st+θ) (6)

N (t) represents DC component, Asin (2 π f_sT+ θ) represent switching frequency component of degree n n, A is amplitude.

$\begin{array}{c}{p}_d=x\left(t\right)\sin \left(2{\mathrm{\πf}}_{s}t\right)\\ =n\left(t\right)\sin \left(2{\mathrm{\πf}}_{s}t\right)+\frac{A}{2}(\cos \mathrm{\θ}-\cos (4{\mathrm{\πf}}_{s}t+\mathrm{\θ}\left)\right)\\ =\frac{A}{2}\cos \mathrm{\θ}+n\left(t\right)\sin \left(2{\mathrm{\πf}}_{s}t\right)-\frac{A}{2}\cos (4{\mathrm{\πf}}_{s}t+\mathrm{\θ})\end{array}---\left(7\right)$

$\begin{array}{c}{p}_q=x\left(t\right)\sin \left(2{\mathrm{\πf}}_{s}t\right)\\ =n\left(t\right)\cos \left(2{\mathrm{\πf}}_{s}t\right)+\frac{A}{2}\left(\sin \right(4{\mathrm{\πf}}_{s}t+\mathrm{\θ})+\sin \mathrm{\θ})\\ =\frac{A}{2}\sin \mathrm{\θ}+n\left(t\right)\cos \left(2{\mathrm{\πf}}_{s}t\right)+\frac{A}{2}\sin (4{\mathrm{\πf}}_{s}t+\mathrm{\θ})\end{array}---\left(8\right)$

It is respectively adopted RAF pd and pq is filtered

${\stackrel{\‾}{p}}_d=\frac{A}{2}cos\mathrm{\θ}---\left(9\right)$

${\stackrel{\‾}{p}}_q=\frac{A}{2}sin\mathrm{\θ}---\left(10\right)$

Can obtain

It is illustrated in figure 4 lock-in amplifier (LIA) theory diagram.

Maximum power tracing

Once obtaining Gdc and gdc, the target of maximum power tracing is i.e.

G_dc-g_dc=0 (12)

Here integral controller is used to eliminate the difference between the two admittance.

Maximum power tracing principle is as shown in Figure 5, it should be noted that the frequency of maximum power tracing and switching device VT Switching frequency f_sUnanimously, sample frequency f_cIt should be the multiple of switching frequency.

By voltage sensor and the output electric current i of current sensor sampled light photovoltaic assembly respectively_PVWith voltage u_PV, by i_PV And u_PVInput RAF obtains i_PVAnd u_PVDirect current component valueWithSimultaneously by i_PVAnd u_PVInput LIA obtains i_PVAnd u_PVOpen Close frequency component of degree n n amplitude di_PVAnd du_PV, willDivided byObtain G_dc, di_PVDivided by du_PVObtain g_dc, use integral controller to eliminate G_dcAnd g_dcError, be adaptively adjusted dutycycle d, produce pwm signal and control the on, off of switching device VT so that Photovoltaic module works in maximum power point.

The present invention provides a kind of quickly photovoltaic module maximum power tracing system and method for tracing, and the present invention is in external environment Can well realize photovoltaic module maximum power point tracking when condition changes, can effectively suppress at maximum power point The vibration of neighbouring output, follows the trail of speed and soon and is easily achieved, improve the generating efficiency of photovoltaic module.

This above example only in order to technical scheme to be described, is not intended to limit；Although with reference to aforementioned enforcement The present invention has been described in detail by example, it will be understood by those within the art that: it still can be to aforementioned each reality Execute the technical scheme described in example to modify, or wherein portion of techniques feature is carried out equivalent；And these amendment or Person replaces, and does not make the essence of appropriate technical solution depart from the spirit and scope of various embodiments of the present invention technical scheme.

Claims (5)

1. a quick photovoltaic module maximum power tracing system, including voltage sensor, current sensor, switching device, institute State the output electric current i of the respectively the most certain frequency sampling photovoltaic module of electric current, voltage sensor_PVWith voltage u_PV, described switching device Controlled break-make by pwm pulse signal, make photovoltaic module be operated in certain power points, it is characterised in that also to include:

Recurrence average filtration module: be used for filtering input signal i_PVAnd u_PVMedium-high frequency periodic disturbance component, in stick signal DC componentWith

Lock-in amplifier: obtain input signal i_PVAnd u_PVSwitching frequency component of degree n n amplitude di_PVAnd du_PV；

Divider: willDivided byObtain G_dc, di_PVDivided by du_PVObtain g_dc；

Integral controller: eliminate G_dcAnd g_dcError, be adaptively adjusted dutycycle d, produce pwm pulse signal and control derailing switch The on, off of part.

Described voltage sensor connects recurrence average filtration module and lock-in amplifier respectively, described recurrence average filtration module and Lock-in amplifier connects divider respectively, and described divider connects integral controller, described integral controller connecting valve device.

2. quickly photovoltaic module maximum power tracing system as claimed in claim 1, it is characterised in that described recurrence average is filtered Mode block takes M sampled value and regards a round-robin queue as, and the length of queue is fixed as M, samples a new data every time and puts into Tail of the queue, and throw away data of original head of the queue, the calculation of M data in the data that wave filter exports every time always current queue Art meansigma methods.

3. quickly photovoltaic module maximum power tracing system as claimed in claim 1, it is characterised in that described integral controller The frequency producing pwm pulse signal is consistent with the switching frequency of switching device, and sample frequency is the multiple of switching frequency.

4. quickly photovoltaic module maximum power tracing method as claimed in claim 1, it is characterised in that comprise the steps:

1) voltage sensor and current sensor are respectively with the output electric current i of certain frequency sampled light photovoltaic assembly_PVWith voltage u_PVAnd Signal is reached recurrence average filtration module and lock-in amplifier；

2) recurrence average filtration module obtains i_PVAnd u_PVDirect current component valueWithAnd reaching divider, lock-in amplifier obtains To i_PVAnd u_PVSwitching frequency component of degree n n amplitude di_PVAnd du_PV, and reach divider；

3) divider willDivided byObtain G_dc, di_PVDivided by du_PVObtain g_dc, and by G_dcAnd g_dcReach integral controller,

4) integral controller eliminates G_dcAnd g_dcError, be adaptively adjusted dutycycle d, produce pwm signal and control switching device On, off so that photovoltaic module works in maximum power point.

5. quickly photovoltaic module maximum power tracing method as claimed in claim 4, it is characterised in that described step 3) in Integral controller can be replaced by pi regulator or PID regulator.