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and design process of hardware and software of PV power station remote monitoring system data acquisition device, collected and monitored the photovoltaic ...
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+