Upload
majid-sattar
View
220
Download
0
Embed Size (px)
Citation preview
7/31/2019 05552301
1/4
Design of Track Control System in PV
Jun-ming Xiao Ling-yun Jiao Hai-ming Zu Rui Zang
School of Electronic and Information EngineeringZhongyuan of Technology
Zhengzhou, P.R. China
[email protected](.M .Xiao) [email protected](L. Y Jiao)
Abstract-S dvlp pplct
cpct kd wbl c wc c
b ctl d v T tck ctl t PV
dpt ttc tck lt tcq t k l pl
lw ppdcl t lt T w c tl pvt td PV dd l tlzt
t dc t ct ptvltc pw T pp l
tdc t bc tct d dw d w d
pc tck ctl t PV, v t dw cct
pt tt td d w ctl pc t
t l t dvt d ddvt
tjct tck d d lctptcl tck d
c t td tt lctptcl tck t j
tck d wl t tjct tck d
ddtl tck d unusualwt cdt
Keywordsphotovoltaic power; automatic track control;
controer; sun trajecto tracking; electrooptical tracking
I.
In the energy crisis and environmental highlight
of today tates have adopted a series of signicant measures to
and support the development of solar energy.
Photovoltaic power is one of the main ways of solar energy
utilization, has the characteristics of environmentally-iendly
and application range is ver wide, has now
been used in comication, transportation and other elds,
has a place in the national economy energy system [1]. At
present, the cost of photovoltaic power generation is too high,
can not be compared with the traditional forms of power
generation, the development of domestic PV power
97814446055710$6.00 010 EEE
517
In order to reduce the cost of PV power, countries
around the world are constantly exploring, at this stage the
more approach are mainly tracking method and the
light-gathering method. Tracking method that is using
model, keep light vertical irradiate photovoltaicarray to improve solar panels' ability of absorb solar
radiation. Track control system in PV using tracking
solar power generation equipment can enhance the power
generation efciency 35%, decrease cost by 25% [2].
II. THE OF TRCK YTEM PV
Fig. The block diagram of track control system in
Solar energy as one kind of clean and non-pollution energy,has very broad prospects for development however there is
the problem of low density, intermittent and space distribution
changes [3], which put forward higher requirements for the
collection and use of solar energy. At present, solar panels of
photovoltaic power generation system are basically xed, can
not make ll use of solar energy resources and generation
eciency is lower. Track control system in PV can
7/31/2019 05552301
2/4
automatically adjust the orientation of solar panels according
to the altitude angle and azimuth angle of sun, make the sun
light always perpendicular incident the surface of photo voltaic
array to obtain the maximum power generation efciency.
As gure I show is the block diagram of track control
system in PV, system uses modular design, mainly composedby photovoltaic array, tracker, sensors, controller, inverter and
other components. Sensors can accurately receive sunshine
within a certain angle and transform it into a measurable error
signal; tracker can handle the error signal which is measured
by sensors, then output motor triggered signals according to
the control algorithm; controller can control the motor's
running and stop according to the motor triggered signals.
III. RCKIG METHOD ND CONTROL TRTEGY DEIGN
PRICLE
A The calculation /sun angle
The sun path changes as the season changes, the
position tracking method can be divided into horizon
coordinates tracking and equatorial coordinates tracking,
horizon coordinate tracking method track the suns
angle and angle, equatorial coordinate tracking
method track the sun's declination angle and solar angle.
Since the change range of solar declination angle is no more
than 2327, its changes slowly so choose horizon coordinatetracing method.
The calculation formula of sun altitude angle a and
azimuth angle s [4]:
a 5 + 5 Bh ( 1 )
s = a - 5 / a
Or, s 5 Bh / a
Where, declination angle
5= 23.4 sin(360x284+n )
36
( 2 )
518
is installation site Bh is solar angle; n is the
days of year.
According to the geographical latitude, the declination
Angle and observation time, using equation (1) and (2) can
calculate the suns altitude angle and azimuth angle at anymoment, any area.
Tracking mode
The tracking mode that adopts at home and abroad
is very much, it can be divided into trajectory
tracking mode and electro-optical tracking according to the
different forms of tracking [5], can be divided into
tracking method and biaxial tracking method according to the
different forms of exercise [6].
trajector tracking mode and electro-optical
tracking mode have some limitations, sun trajectory tracking
mode need to positioning before running, can not
carry on automatic when sun angle calculation has
errors. Electro-optical tracking mode under the of
the weather greatly, appear not to track or wrong track
of the of the weather problem, especially in
weather conditions may occur motor reciprocating
motion result in the waste of energy. This paper
selected the biaxial tracking method of trajectory trackingmode combined with electro-optical tracking mode. In the
of strong light using light intensity detect circuit
detect ray deviation to electro-optical tracking, In case of
weather changes the system automatically turns into sun
trajectory tracking mode.
C Control mode
In photovoltaic power tracking system, control mode can
be divided into three types of open loop, closed loop and
hybrid control according to whether exist feedback while thecontrol system control the quantity control. the open
loop control mode is and easy to realize, has
the problem of tracking when the
overcast and rainy days, system will consume large amounts
of power. Therefore, this article selected the closed loop
control mode. Closed loop control mode schematic diagram is
shown as Fig.2.
7/31/2019 05552301
3/4
As the gure shown, closed loop control mode is using
sensor detect the deviation of the incident light rays of sun
and system optical axis, when the deviation over the threshold,
drive machine part tu to move through motor, reduce the
deviation until the sun ray and system optical axis afresh
parallelism, realize the tracking of the solar altitude angles
and azimuth Angle.
Fig.2 Closed loop control schematic diagram
IV. EIGN OF YTEM HD
A The basic composition ofhardwarePV tracking controller is a power plant that can make the
solar panel track the orientation of at any time and
the light vertical irradiates to the solar panel. It's mainly
compose with sensor, light intensity detect
temperature detect circuit, current/voltage detect circuit,
stepping motor, motor driver and other the hardware
is shown as Fig.3.
Fig.3 Controller hardware block diagram
Light intensi detect circuit
The 14 parameters that PV tracking system can detect are
the output of PV arrays, battery chargingelectric current/voltage, AC current and AC voltage of
inverter, environment battery PV
arrays environment light intensity, tracking light
intensity, sun altitude angle, angle and wind velocity.
Light intensity detect circuit schematic is shown as Fig,
is mainly consisted by photosensitive sensor, integrated
operational amplier, triode, resistance, capacitance and other
519
elements. Phototransistor and tu on aer accept
sunshine, triode ampli the electrical signals. The voltage
across the voltage follower is equal, avoid the mutual
inuence of ont and back electric circuit, differential
amplier amplify two voltage's dierence value.
Comparator's voltage VDID2 compared with reference
voltage Vref, if the co-rotating voltage larger than the
reverse input voltage, the output is high-level, else is
low-level. The motor run while the compare result VI is
low-level.
FigA Light intensity detect circuit schematic
C Stepping motor driver circuit
Stepping motor is one kind of that converts
electric into displacement, in the tracking
control system the controller's output signal as stepping
motor driver's input control signal, in order to control
stepping motor's positive inversion of longitudinal direction
and horizontal direction. As Fig.5 shown is one of the
stepping motor drive circuits, the system totally have
stepping motor drive respectively drive steppingoto's postve veso o decto ad
horizontal direction.
Control goes into transistor after 74LS 14 reverse
phase, the amplied by the transistor, then control
photoelectric switch. Aer photoelectric isolation, carry on
the voltage and amplication by power then
drive each phase windings of stepping motor, make stepping
7/31/2019 05552301
4/4
motor do forward, backward, speed up, slow down or stop
movement. As Fig.5 shown L is one phase winding of
stepping motor, RL is winding internal resistance, R IS
exteal resistors, has the nction of limit current and
improves the circuit time constant, the shunt capacitance
across the exteal resistors can enhance the high equency
performance of stepping motor, D is y-wheel diode, avoid
power tuber's damage because of the back electromotive force
that produced by motor winding.
+25V
Fig.S tepping motor driver circuit
V. YTEM OFTWRE DEIGN
0
Fig.6 ystem operating procedures
The soware part of PV tracking control system mainly
include ma program, data acquisition
monitoring subroutine, electro-optical tracking subroutine,
trajectory tracking batter charge and
discharge subroutine, and so on, control ow is shown as
Fig.6. The system can detect signal acquisition,
display, query, etc, can carry on real-time or historical data's
graphics image processing and print for the
information stored in the database, has the nction of
self-calibration, self-diagnosis and self-test. At the same time,
the system can adjust the position of PV array
according to test in order to achieve real-time tracking
target.
VI.
and of solar energy is one of the
effective solutions of energy crisis and the effective
means of reducing environmental pollution, solar photovoltaic
cell array's power generation has relation with the incidence
angle of the generation is the largest when ray
to the PV array. PV tracking control system
using light automatic tracking mode to make solar battery
always perpendicular to this method can greatly
enhance the capacity of solar array, reuce the overall cost ofPV power generation, create high economic eciency, meet
the of setting the environmental protection
economy energy type social, has the theory research meaning
and application prospect of promotion.
REFERENCES
X.K.Li. "Photovoltaic power development and policy analysis, un
[2] F. and P. "Design of controller for lltracking solar, Foreign electronic components, volA, pp. 4-6, 2007.
[3] J. L. Li and . B Zhou. "Design of a new kind of solar photovoltaicpower tracking system, Electrical applications, vo.28, pp.68-71, 2009.
[4] P and Y F hen " powe ytem aed on ntellgentsun tracking with low power cost, Measurement and controltechnology, vo.27, pp.36-39, 2008.
[5] X. H. Wang. "Design and research of multiple plane mirrorcondensation solar tracking system, Hefei, Hefei university, 2007.
[6] B X. Zhang. "Research of solar energy utilization tracking and gathersystem, Hefei, Hefei university, 2006.