英语论文网

special function can be
determined by different customers according to their needs.
Compared with traditional instrument, the virtual instrument
will significantly shorten the developing cycle of a system
using software programming rather than hardware
equipment. The system described in this essay used data
acquisition card NI-USB 6008 to get the data which has
experienced the conditioning process, including temperature
of PV array, current and voltage generated by PV array . NI
USB 6008 has 8 analog inputs with 2 analog outputs. Its
maximum sample rate is 10kS/s and its input voltage range is
±10V. As most of signal collected in this system is DC
voltage signal, the sample rate is enough for use in this
system.
II. HARDWAREE
Wind power system is composed of a wind turbine, a
rectifier, a battery charger, a battery, an inverter and DC/AC
loads; the facility used for get the wind velocity signal is the
anemograph [4], shown as the Fig.2.
Fig 2. The hardware of the measured system
Wind turbine generates energy in the system. The rated
power of the wind turbine that is been measured here is
300W. The rectifier is used to transfer the AC voltage
generated by the wind turbines to DC format. The battery
charger is also important equipment used in the system whose
main responsibility is to detect the input voltage and current
to control the charging and discharging of the storage battery,
A Test Facility for the Data Acquisition and Signal Analysis of the
Wind Power System
Gang Yang, Student Member, IEEE
A
34
978-1-4244-1888-6/08/$25.00c 2008 IEEE
the voltage of which can be chosen according to different
systems [5, 6]. When the power generated by the system
exceeds the load’s demand, the controller sends the required
power to the load while at the same time stores the residual
power in the battery. When the power generated by the
system is insufficient to meet the load’s demand, the energy
stored by the battery will be used to maintain the stabilization
of the load. As to the battery, Lead-acid storage battery is
preferred for its low cost, high capability and free
maintenance. The system is capable of providing not only
steady DC voltage to drive the DC load but also the AC
voltage to drive the AC load, towards which the Inverter is
used.
III. SOFTWARE DESIGN
The data acquisition card is controlled by a properly
developed program using the LABVIEW software, running on
the PC. It consists of two parts: (a) a graphical environment
with components such as displays, buttons and charts in order
to provide a convenient-to-use environment for the system
operator, and (b) the block diagram, which consists of built-in
virtual instruments (VI), performing functions such as analog
channel sampling, mathematical operations, file management
etc [7, 8, and 9]. The flow chart of the developed LabVIEW
program is illustrated in Fig. 5.
st ar t
dat a acqui si t i on
di spl ay resul t s
Fouri er Transf orm
Aut ocorrel at i on Transf orm
st ore resul t s
st op command?
st op
Y N
Fig. 3. Flow chart of the LabVIEW based testing system
Initially, all analog signals are sequentially sampled and
the input voltage data is collected by the data acquisition card.
Then the program shows the relative curves and values on the
front panel. The Fourier Transform is