Proceedings of the
2011 International
Conference on
Advanced Mechatronic Systems, Zhengzhou, China, August 11-13,
2011
Design of PV Power Station Remote Monitoring System Data Acquisition Device Junming Xiao, Pengcheng Liu, Lingyun Jiao, Haiming Zhu, Yinghu Du
Abstract-This paper mainly introduced the basic structure and design process of hardware and software of PV power station remote monitoring system data acquisition device,
II.
THE STRUCTURE AND FUNCTION OF REMOTE MONITORING SYSTEM
collected and monitored the photovoltaic power generation system voltage,
current,
Reset and watch-dog circuit
temperature, gave the bidirectional
current sensing circuit, temperature detection circuit, serial communications interface circuit and remote communication diagram
of PC and single chip microcomputer, the conditioning circuit of inverter AC voltage and current, data
Voltage and current signal acquisition
acquisition flow chart and so on. Aiming at the large scale
module
parallel centralized development trend of PV power station, using group control technology, in the case of low sunshine data acquisition centralized control inverter to make inverter turns operation, greatly extend the service life of the inverter.
Luminous intensity signal acquisition
The system could complete the data acquisition and processing PV station operating and the power parameters instantaneous value of electrical equipment operating status,
module
of
realized dynamic curves and report shows and print function of realize real-time and historical data.
Keywords: PV power station; remote monitoring; data acquisition; group control technology; bidirectional current sensing circuit I.
Output
Temperature signal
control and
acquisition module
alarm si nal Fig.l System hardware structure
INTRODUCTION
As figure
1
shown is the system hardware structure
Energy is the essential economic foundation of human life.
diagram, its core is micro-controller. The whole control
Reliable, safe supply of energy and clean, efficient energy
system consisted of data acquisition, AID conversion and
utilization is the basic guarantee to realize the economic and
reset and watch-dog circuit, output control, clock chips,
social development. People pay more and more attention to
serial communication, LCD display and print drives and
solar energy, which is an inexhaustible clean energy, PV 1, 2 draws the most attention [ 1. In order to improve the
other peripheral circuit. Functions as follows:
efficiency of photovoltaic power generation system and understanding the local solar energy resources and the
(1)
natural environment, photovoltaic system must be monitored and
controlled
[31.
Traditional
photovoItaic
monitoring
system is generally close monitoring maintenance staff on site need to keep continuously monitoring the data shown in equipment and making the corresponding treatment. A large part of the current constructions of photovoltaic power
(2)Monitoring AC voltage and current: inverter output voltage and current; (3)Temperature
this paper adapts the way of combination of telephone lines and RS-232 bus to transfer data. With the existing telephone
testing:
environmental
temperature,
battery surface temperature, room temperature and battery surface temperature;
station are in remote areas where the environment is not suitable for long-term duty. To solve these above problems,
Monitoring DC current: current of photovoltaic cells
and battery;
(4)Collecting PV power system environment parameter, battery array, electrical equipment operation parameters and the grid parameters;
network, remote monitoring the operation of PV power
(5)The system could real-time monitoring the operation
station, making the PV power station built in remote areas do
state of PV power station. When the equipment malfunction
not need staff on duty. Save of manpower resources has great significance for further promotion and application of
it can immediately issued a warning signal, promptly notify
the staff to handle the accident [41.
PV power station.
(6)ln the process of battery charge and discharge, the system can effectively monitor the various states of battery
JM. Xiao, P c. Liu, LY Jiao, H.M. Zhu, YH. Du are with the School of Electrical and Information,
Zhongyuan University of Technology,
41
Zhongyuan Road, Zhengzhou, China, 450007.
[email protected](JM. Xiao),
[email protected](P.c. Liu).
array.
With
control,
existing
telemetry,
adjustment;
978-0-9555293-7-5/11/$25.00
the
telephone
network
to
remote
monitoring PV power station, realize the function of remote
367
remote
communication
and
remote
(7)Storing the operation information of PV power station,
monitoring systems need to have bi-directional current
realize the graphic display and printing of real-time data and
sensing function to measure battery charge and discharge
historical data.
current.
Except the general function, the system using group control
technology,
through
centralized control
of data
acquisition to make inverter "rotate the leadership", inverter turns into operation in the case of low sunshine. This can improve the efficiency of low sunshine, extend the life of the inverter, achieved the n+x redundancy, increasing capacity prediction and energy management functions. III.
�---1"'"0""i1JT O,..,.l.i..! J +---+
TWO-POINT SAMPLING ALGORITHMS
There
are
two
ways
to
acquire
power
station
AC
according to the different sampling signals, they are DC
GND
sampling and AC sampling [51. DC sampling algorithm is simple and easy to filter. However, it has the problem of
large investments and maintenance complex.
AC sampling
has the advantages of good real-time, phase distortion, less investment and easy to maintain. AC sampling have wide range of application, there are many algorithms according to
Fig.2 Bidirectional current sensing circuit
the different application. It can be divided into sinusoidal model algorithm and the non-sinusoidal periodic model
algorithm in accordance with the model function [61, in the
sinusoidal model algorithm there are a single point of sampling, two sampling algorithm, etc. This article adopts two sampling algorithm.
u,
Suppose
u,
Urn sineOJt + rp)
(I)
Urn sineOJt + rp + 90°)
(2)
=
=
U,2 +U 2 2 U"� sin2 (OJt + rp) + U:, cos' (OJt + rp) =
=
U�
:. U
=
(3)
. .
SImIlarly 1
=
=
(4)
rt:+t: ��
Figure 2.
VREF is set as zero detection voltage, when part
A works, the circuit output voltage is higher than
�IS+
>
�IS-'
works,
VREF '
battery power for the load; when part B
the
circuit
�I"F ' �IS+