Power distribution monitoring system based on cdma communication

Xiamen Caimore Communication Technology Co.,Ltd
2 F, 37#, Wanghai Road, Software Park 2, Xiamen,China (361009)
Sales06@caimore.com skype:caimoremichelle
Tel:+86 592 5901215 Web: www.caimore.com/emain.asp
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Power distribution monitoring system based on CDMA communication
Solution
This paper proposes a power distribution monitoring system based on CDMA design
principle and implementation scheme, briefly introduces the basic knowledge of CDMA
technology, describes the CDMA wireless transmission method to realize the remote data
monitoring application.Through practical application, to obtain the ideal effect.
1 . Foreword
With the development of science and technology to achieve low-voltage distribution
network has become a trend in the power system automation development. Low-voltage
distribution network as the last link in the transmission and distribution system, and its
implementation is closely related to the degree of automation and the quality and reliability
of electricity supply. To this end, the need for network automation special article on
low-voltage distribution and its implementation as a simple discussion.
Distribution transformers are assigned directly to low-voltage electrical energy user
electrical equipment, its operation data is an important part of the whole distribution
network underlying data. Thus, monitoring its operating parameters and states are
necessary. This article discusses the use of CDMA as a means of communication, the
establishment of distribution transformer monitoring system.
In the communication distribution transformer monitoring system, you can use digital radio,
GSM SMS, fiber access and other means. Radio data transmission advantage is in
addition to the annual frequency fee, usually run at no additional charge; the disadvantage
is greatly influenced by topography, climate, resulting in system reliability, real-time poor,
unable to take the initiative to report. GSM short message can take the initiative to report;
drawback is that Article charges, high operating costs, but also in the short message
center server busy holiday for a long delay. Reliable fiber-optic communications, but
construction costs into a large, poor scalability, equipment maintenance inconvenient. The
CDMA communication will avoid the above problems.
CDMA is a number of new wireless data transmission services, the purpose is to provide
users with high-speed wireless IP or X.25 service. CDMA theoretical bandwidth of up
171.2Kbit / s, the actual application bandwidth is about 40 ~ 100Kbit / s, in this channel to
provide TCP / IP connection, can be used to connect INTERNET, data transmission
applications. CDMA uses packet switching technology, each user can simultaneously
occupy multiple radio channels, the same radio channel can be shared by multiple users,
resources are used effectively. CDMA allows users to send and receive data at end packet
transfer mode, without the need to use circuit-switched mode network resources. CDMA
always online, according to traffic accounting, thus providing an efficient, low-cost wireless
packet data services. Especially suitable for intermittent, sudden and frequent many
points scattered, small traffic data, but also to the occasional large data transfers.
2 , the system structure
Development objectives distribution transformer integrated management system is to
create a safe and reliable and can provide a variety of advanced services, and promising
application execution and implementation capabilities provide a strong platform and open
the platform to run multiple independent system application subsystems, to become a

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modern management system in line with the distribution requirements, distributed, open,
modular, scalable distribution transformer integrated management system. In addition to
the basic platform to provide basic hardware technologies and operating system kernel,
but also to provide basic services such as database systems, information transmission,
human-machine interface, real-time environment applications. Each application based on
the underlying platform subsystem includes: distribution transformers management, line
loss management, automatic meter reading, VQC function, harmonic data, available
power management, data query, automatic reports, charts, and interfaces with other
systems . Among these subsystems organically horizontal and vertical integration in open
systems architecture (OSA) form the basis for a complete distribution transformer
integrated management information system.
CDMA Network Architecture distribution transformer monitoring system as shown below,
the system is divided into four parts, which are master control center, network proxy,
CDMA data transmission terminal, control terminal equipment. Master main complete
interactive work; network proxy server is mainly responsible for network data link
establishment and data transceiver transparent transit; on CDMA data transmission
terminal is completed and sent messages issued; monitoring terminal equipment mainly to
complete the digital and analog acquisition.
This system can be used in a network proxy ADSL, LAN and other INTELNET public
network connection, using the public network fixed IP or dynamic public IP + DNS
resolution service, for security reasons, the monitoring center master station LAN, not
directly connected INTERNET, through the network proxy server for network data link
establishment and the transparent transfer of data sent and received.
After power on data transmission terminal CDMA, it will take the initiative to access the
network proxy server based on pre-set in its internal IP address or domain name, set up

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TCP / IP link through a proxy server and the monitoring center. Monitoring center master
station itself maintains access to IP address and ID number for each terminal, when the
master would like to propose a monitoring terminal data request, it will be based on IP
address and ID number to find the corresponding terminal, the command sent to the
terminal after the terminal responds with GRPS data transmission terminal to send data to
the network proxy server port forwarding through the port alluding to the master control
center, which completed a reply -like communication flow.
The above approach is implemented through the Internet, so that the user to achieve cost
is relatively low. If you need high reliability of data transfer. China Unicom for such
application provides direct access to CDMA networks. Direct access to the monitoring
center master station Unicom CDMA base station through the green way, and get a fixed
IP address. Monitoring sites and data without routing to the Internet network, monitoring
points DTU also uses SIM card fixed IP addresses. In this way the composition of the
point to multipoint networks with real-time, high security, but the relatively high access
fees.
Third, the monitoring terminal
The monitoring system uses power distribution integrated monitor is based on DSM
technology requirements and distribution transformer monitoring relevant standard design
and manufacture of a high-tech products. It uses high-precision digital sampling
technology, data acquisition, display, storage, communications and other functions into
one, and through background software will store the recorded data is displayed in the form
of a chart or a report, printing and analysis. Its leading technology, powerful, high reliability,
and can be widely used to monitor the distribution automation system. Its main features
are:
The basic measurement parameters:
Three-phase voltage, current, frequency, active power, reactive power, power factor,
four-quadrant power, temperature and other nine categories, more than thirty parameters.
Technical parameters
• Rated Technical parameters
Rated voltage Un: 100V
Rated current In: 5A
Rated frequency Fn: 50Hz
• measurement accuracy
Voltage / Current / Frequency: 0.2
Power factor / active / reactive power: 0.5
Active power / reactive power: 1.0
• Built-in flash memory capacity
Storage capacity: 1024k bytes, can achieve 84 consecutive days electricity consumption
data recording (every 15 minutes of recording time)
Accuracy
Voltage / Current / Frequency: 0.2
Power factor / active / reactive power: 0.5
Active power / reactive power: 1.0

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System parameter
Means of CT, PT ratio
Data storage interval
System Clock
LCD contrast
Overvoltage parameters
Brown parameters
Overcurrent Parameter
Fourth, the data transmission terminal - using only Mao Communication Technology Co.,
Ltd. Xiamen CM 6550P CDMA DTU
CM 6550P CDMA DTU using high-performance industrial embedded ARM9 processor,
real-time operating system software support platform, embedded proprietary TCP / IP
protocol stack. To provide users with high-speed, reliable, always-on data terminals,
multiple protocol conversion of a virtual private network. For user-network flow control
products support voice, messaging, data and on-line trigger automatic disconnection
timeout function. Also supports dual data center backup, and synchronize multiple data
centers to receive data, and other functions. Our products have been widely used in
finance, water conservancy, environmental protection, electricity, postal services,
meteorological and other industries.
A radio parameter
1, support the IS-95 A / B and CDMA2000 1xRTT wireless network
2, supports 13K QCELP audio codec
3, support for data, voice, SMS and fax
Second, the hardware system
1, CPU: ARM9 industrial-grade high-performance embedded processors, 200MPS, MMU,
16KB Dcache, 16KB Icache
2, FLASH: 8MB, can be expanded to 32MB
3, SDRAM: 64MB, expandable to 256MB
4, the interface:
An RS232 serial port. (If necessary, can support RS422 / RS485), serial port speed 110 ~
230400bits / s
LEDs: a power, communications and online indicator.
Antenna Interface: standard SMA female antenna interfaces, the characteristic impedance
of 50 ohms.
UIM card interface: 3V / 5V standard user card interface putt.
Power Interface: standard 3-pin power jack.
Voice interface: standard headphone microphone interface.
5, power supply:
External power supply: DC 9V 500mA
Wide voltage power supply: DC 5-35V
Communications Current: 350mA
Standby Current: 35mA
6, size

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Dimensions: 92.7x61.3x23 mm (not including antenna and fixed parts)
7, the other parameters:
Operating ambient temperature -25 ~ + 65ºC
Storage temperature -40 ~ + 85ºC
95% relative humidity (non-condensing)
Third, the software features
1. Intelligent anti dropped support of online testing, online maintenance of automatic redial
dropped calls, to ensure that equipment is always online.
2. Support RSA, RC4 encryption algorithm
3. Support virtual duty VWM (Virtual Man Watch) function to ensure stable and reliable
system
4. Support for virtual private network data (APN)
5. Transparent data transmission and protocol conversion, support multiple operating
modes
6. To support the data center dynamic domain name and IP address access
7. supports dual data center backup
8. Support multiple data centers
9. Support SMS, voice, data and other wake-up mode and network connection timeout.
10. Support SMS backup and alarms.
11. multiple hardware and software watchdog
12. The packet transmission status reports.
13. The standard AT command interface
14 can be used as an ordinary dial-up MODEM
15. Support telnet function.
16. Support remote configuration, remote control
17. Adoption of serial software upgrade
18. supports LINUX and WINDOWS operating systems
19. There are software and hardware dual watchdog, in the DTU does not work, can
automatically power reset.
Fourth, the monitoring center master station
Master system innermost layer is the operating system and system software. The second
layer is a layer of software system support, including database systems, power system
models, data acquisition and transmission. Power system model mainly refers to the
object of power system equipment and network topology; points runtime database system,
basic library, the library and the historical library of four parts; data acquisition and
transmission is a variety of data collection from different terminals according to various
communication protocols over, but not for processing, and then distributed through a
network of systems need the data. The third layer is the basis for the application layer, the
data will be collected through various processes come through GUI interface to the user.
The fourth layer is the advanced application layer, the data it produces mainly for the
power system management and decision-making further use.
PC software provides the following functions:
(1) distribution transformers transformer SCADA system operation monitoring,

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transformer monitoring abnormal situation, analysis, processing and archiving data,
parameter settings and status display RTU. Access to both distribution network run basic
information, but also provide a good basis for the functional expansion.
(2) automatic meter reading system will automatically copy the user's electrical
distribution transformers and degree according to the set time. And having abnormal
meter alarm meter track record and operational records and other auxiliary functions.
(3) the user to purchase energy management for users with poor credit, it is powered
after the first purchase, and warnings when using power to achieve certain proportion
through the system.
(4) Loss Management District Line main line loss management and loss management.
(5) distribution equipment management is the management of distribution lines and
distribution transformers and other equipment.
(6) the wrong terminal identification terminal error recovery into communication,
communication is interrupted (called a terminal three consecutive undetectable), wireless
terminal error (called ten times a day undetectable), wireless interruption (continuous had
thirty terminal called undetectable).
(7) Load forecasting by calculating the master station and sub-stations of all the total
active power total value added of the stage area to the next stage of preliminary estimates
of load conditions.
(8) The capacitor switching is adjusted on the spot according to the voltage and power
factor, the time factor to consider when adjusting and switching frequency. In case of
failure can be adjusted in situ remote monitoring and remote control. If the terminal
unregulated switching function, the system can calculate the distance control capacitor
switching.
(9) remote terminal operations can be read or set parameters of the terminal, such as a
transformer tuning parameters. You can set switch is closed, the switch opening. VQC
parameters can be read or set.
(10) Marketing System Interface database can easily provide data source for the
marketing system.
(11) through the harmonic data acquisition system capable of capturing each user
harmonic content.
(12) increases user management user stealing electricity and power is converted to
electricity comparison, by setting the scale factor, for a warning, such as when the active
power generation and electricity does not move, a warning is generated.
V. Conclusion
Realization of China's low-voltage distribution automation, is to improve the quality of
power supply, power reliability and improve their level of need for the power companies,
CDMA as a new means of communication, used in distribution automation has many
advantages, CDMA-based communication Distribution Transformer Integrated
Management System is a more promising implementation.

Power distribution monitoring system based on cdma communication

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Power distribution monitoring system based on cdma communication