2006 International Conference on Power System Technology

Monitoring System of Distribution Running StatesBased on Broadband Power Line Communication

Xu Zeng* 2, Ming Liang*12, Huaizhi Liu*3, Yan Ren*12 and Rui Yang*12*1RCIEPT, North China Electric Power University

No.2, Beinong Road, Beijing, 102206, China*2 Taiyuan ZHONGBO Information Science Institute,

Room 501, No.11, Science and Technology Street, Hi-tech Zone, Shanxi 030006, China*3Taiyuan Communication Network Management Office of Beijing Military Area

Taiyuan, 030006, China

Abstract--Nowadays, the domestic and foreign technologies ofLow Voltage Broadband Power Line Communication are gettingincreasingly mature and perfect, and it has come into successfulapplications in our country. Compared with other systems of thesame kind, the system based on Broadband Power LineCommunication has the benefits of timely and reliable datatransmission, observing monitoring sites via real-time videoimage, low system cost and little maintenance. Therefore, thepaper proposes the monitoring system of distribution runningbased on Broadband Power Line Communication, introducesconstituted of hardware and software in detail, and discussesfunctions and characteristics of this system.

Keywords--Broadband Power Line Communication, Distribution

Running, Real-time Video Image

I. INTRODUCTION

Electricity relates to the vial life line of our national

economy, which is the main guarantee of modern

construction. Now electric industry in our country is in the

highly-developing phase, therefore, to satisfy the

requirements for high power supply quality and service level,a kind of monitoring system of distribution running is needed,

which can real-time monitor and manage the running states

of electric meters and transformers, realizing the synthetic

functions of focus storage and monitoring. So electric

department can improve controlling management and

monitoring capability for the systems of power supply check,

charging and corresponding accounting and charging of

electric energy. Combined with the current states of electric

power system, this paper proposes a monitoring system of

distribution running based on BPLC(Broadband Power Line

Communication). In this system, the transformer is used as

the master station, and those customers in control of it as

slave ones. Moreover, this system gathers information of

quantity of user electric charges and video picture data from

key devices(e.g. electric energy meter, transformer, etc.) with

PLC terminals. Then distribution network is directly used as

the communication channel (not the traditional power line

carrier mode) to transfer data to master station and store them

in it. Also data is analyzed and alarmed with smart software.

Thus, this system implements the integrated functions of

focus storage and power supply management, so that it

greatly promotes management and economic benefits, finds

out and treats abnormal circumstances timely to clear faults

and hidden trouble in the very beginning.

II. COMMUNICATION MANNER OF THE

MONITORING SYSTEM

As automation of distribution network is energetically

implemented and reconstructed in our country, power supply

bureaus in cities have deployed optical fibers to 35kV

transformer substations. Therefore, as long as we find an

effective way with low cost to deal with data transmission

problems between user ends and 35kV transformer

substations, it can help power supply bureaus to build their

own monitoring systems to effectively realize management of

distribution monitoring around transformer substations.

The communication modes common used now include

general public network PSTN, GPRS wireless mode or power

line carrier. As for PSTN or GPRS, it does not in restraint of

transfer distance, but it has the problems of deploying extra

lines or dropping off too easily, and it not only can not

guarantee the reliability of data transfer, but also needs highconstruction cost and maintenance charge. The manner of

1-4244-0111-9/06/$20.00c2006 IEEE.

power line carrier realizes electric energy feed and data

communication using the established distribution network,

but it has the problems of strong signal attenuation, serious

interference and time variation; while Therefore, it is difficult

to realize real-time monitoring of distribution running in

large range according to the above methods.

Broadband Power Line Communication is a kind of

communication technology, which uses Medium Voltage(MV)

& Low Voltage(LV) distribution network as the

communication media to implement transmission of data,

voice and real time image. Nowadays, many low voltagebroadband PLC access and meter-reading sites have been

available, coming to commercialization. Meanwhile, medium

voltage broadband PLC technology is continuously

developing, and devices of MV&LV PLC with 200Mbps or

above have come out. Thus, after advanced technologies are

applied to the monitoring system of distribution running, it

will not only overcome the shortcomings of the above

communication manners, but will transmit general data

information effectively as well as video image data on the

key monitoring sites according to the requirements depending

on its advantages of bandwidth. On the basis of no extra

investment, it adds an important function to the system to

monitoring the vital monitoring points more visually and

obviously.

III. MONITORING SYSTEM OF DISTRIBUTION

RUNNING STATES

A. Structure of Monitoring System

This system is a monitoring system of distribution running

states, integrating many advanced technologies includingenergy saving, preventing electric-theft, tracing and

monitoring. PLC MV Master/MV repeater, PLC LV

master/LV repeater, PLC gateway and PLC terminals are also

included in the system. Transmission rate of MV devices is

205Mbps and transmission distance is longer than 1500m;

transmission rate of LV devices is 4.5Mbps, transmission

distance is far than 1000m except transmission rate of 300m

or above of PLC gateway, transmission delay is less than

10ms. This system is composed of the master station center

in transformer (including master server, monitoring terminal,

printer and PLC MV master), communication channel

(including MV&LV distribution network, PLC MV&LV

repeater, devices for signal to cross transformer (1 PLC MV

master+1 PLV LV master), PLC LV master and PLC gateway,

etc.) and slave stations in user side or transformer (including

PLC terminal, multi-functional digital electric energy meter

and), as is shown in Figure 1.

* t~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

3 XI-~~~~~

Figure1 Structure of Monitoring System of Distribution Running States

Based on Broadband Power Line Communication

B. Hardware and Software of the System

Hardware of System

(I)PLC gatewayThe gateway is used for data connection between two

networks. With PLC gateway, packets and format conversion

among different networks are processed, so one network can

recognize and process application data from other ones. PLC

gateway provides the slave stations connected with full

functional electric access. First PLC terminals connect digitalenergy meters or camera in slave stations to LV distribution

network, and then PLC gateway as the master controller of

terminals to provide electric access from out-station for these

terminals. PLC gateway supports data transmission rate of

4.5Mbps and can transfer various data, voice and video

signals. It is equipped with 1010OBase-TX Ethernet

interface, which enables it to connect PLC terminals to LV

power line. When the master outside the slave stations is in

control of LV power line, PLC can ensure communication

between networks within the slave station. And PLC has

many secure features, which provides security for data of

power line users; meanwhile, DHCP and FTP service as well

as automatic remote configuration are supported. Parameters

are as follows:

O Frequency band: 1.6-12MHz

( Modulation: OFDM

Kg) Data transmission rate: 4.5Mbps

I Distance: 300m

( Capability of handling up to 64 MAC addresses and 32

PLC connections

(2)PLC terminal

Acquisition of electric energy data from digital electric

meters; acquisition of three-phase voltage, three-phase

current, three-phase power and frequency; acquisition of

picture data of monitoring point from camera; acquisition of

data about transformer from TTU. Parameters are as follows:

O Frequency band: 1.6-12MHz

( Data transmission rate: 4.5Mbps® Data interface: 3xDVI/USB2.0 interface(camera);

1GxRS-485/RS-232 interface(Digital electric

energy meter and TTU terminal)

(3)PLC MV master

It is capable of injection and pick-up of power line signals,

which can pick up signals directly from PLC terminals in

transformer slave station to MV power line as well as pick up

from MV power line to master station. Thus, connection

between PLC terminals and master server is set up and data

switch is processed. And it can retrieve signals during the

frequency between 3M and 34MHz. The LV power line

network provides efficient, reliable and high-speed backbone

interface. Parameters are as follows:

(0) Frequency band: 3-34MHz

( Modulation: OFDM

Y2) Data transmission rate: 205Mbps( Distance: 1500m

(4)PLC LV master

Connect more than one slave station to LV power line with

PLC LV master to control LV access network and the

connected slave networks. It is combined with PLC MV

master as a device for signal to cross transformer, so that

signals from MV line can be safely transmitted to LV line or

further to user terminals. It has the data transmission rate of

4.5Mbps, and are capable of handling up to 1024 MAC

addresses and 64 parallel PLC connections. Parameters are as

follows:

O Frequency band: 1.6-12MHz

( Modulation: OFDM

® Data transmission rate: 4.5Mbps

I Distance:1000m

(5)PLC repeater

It not only simply amplifies signals(If so, noises are also

magnified at the same time), but completely receives signals

from insulting devices or another repeater, removes noises

and corrects errors, resolves IP and routing data packets, and

transmits data packets that have been processed to MV line.

Featured with standard 10/100 Base-TX Ethernet interfaces,

a PLC environment controlled by LV master can be easily

connected to the backbone network via MV line, while MV

repeater transmits data between master and slave stations

with interfaces to upload data and download control signals

from master station so as to achieve the repeater function.

Compared with LV power line, the distance that MV line

covers are much longer, so more PLC repeaters should be

installed on the line according to specific distance to ensure

signal to be safely transmitted to the master station.

Software of Monitoring System of Distribution Running

States

Software of Monitoring System of Distribution Running

States based on Broadband Power Line Communication is a

upper machine software specially designed for the

monitoring system. It includes nine major modules of

parameter configuration, Picture process, charge calculation,

real-time monitoring, line-loss calculation, report print,

inquiry, data management and system task, as is shown in

Figure 2.

Real-time Monitoning Parameter Picture Process System Task InquiryModule Module Module Module Module

Monitoning System ofDistnibution PowerNetwork and Customer Information

Line-loss Calculation Charge Calculation Report Pnnt Data ManagementModule Module Module Module

Figure 2 Structure of Software Modules for Monitoring System of

Distribution Running States

This monitoring system mainly has the following

functions:

1) Remote meter-reading: realize remote reading data of

electric energy meter using power line communication.

2) Data acquisition: real-time acquire and report the

following data of LV distribution tank: three-phase

voltage, three-phase current, electric energy, switch

status, power factor, overall time when voltage and

current exceed upper and lower limits.

3) Thread loss: calculate thread loss of slave station or

specified out-thread tank and switch areas according to

different time sessions. On the basis of demands, draw

the thread loss curve in terms of hour, day and month,

and analyze abnormal electric cases of users.

4) Real-time Monitoring and Alarm: real-time watch and

maintenance parameters of electric meter, and view data

on it. Receive alarm information when devices goes

wrong or electric meters make alarms. Users' electricity

thieving actions can be caught at the beginning, and it

can deal with them correspondingly to prevent the loss

of electrical resource effectively.

IV. FUNCTIONS AND CHARACTERISTICS

A. Functions

Due to the flexible deployment of PLC, it can cover the

cell areas conveniently and remotely real-time monitor

transformer and electric meters of users. As for this system, it

can automatically realize data acquisition and storage,

monitor transformer and electric meters and statistically

analyze real-time and history data with PC in the master

station, having the following functions:

1) Electric energy management: it adopts data acquisition

system with high reliability and electric multi-access

digital communication machine based on freely error

correct and allowance technology with high

signal-to-noise. Automatically observes data on the

electric meters, and accurately counts energy. Burden

trace and forecast as well as draw burden curve.

According to burden distribution of each time segment,

distribute and transmit energy reasonably to reduce

burden fluctuate. In terms of burden analysis, it

provides with fundamental bases of power grid structure

adjustment, form the best burden preparation scheme to

enhance running efficiency and reduce line loss.

2) Management of power supply reliability: master

real-time running of MV&LV distribution network and

timely make scientific and reasonable adjustments to

clear hidden troubles of accident in the very beginning,

making it possible for the electric power supply to keep

stable and reliable to enhance power supply security.

Completely in control of running status of transformer

and distribution network. Make statistics of

mathematical theory and online diagnosis for running

data, study actual status, changing trend and regulation

of running devices, make out scientific forecast and

access. Change "periodic maintenance" to "Status

maintenance". Actual running status maintenance takes

in place of fixed maintenance cycle to maintenance

efficiency and further to enhance power supply

reliability. Report time when power cut automatically,

classify them, and calculate reliability ofpower supply.

3) Management of power supply quality: timely master the

parameters including electric quality, voltage, current,

power factors, voltage power supply, power cut add-up

time, current overload, temperature beyond limits,

electricity leak, CT short circuit via real-time

monitoring transformer, electric meters and attached

gauge. Thus, the power supply departments can know

about security of devices, qualified rate of electric

quality, time and mode of electric theft in time. Prompt

power supply to take corresponding measures so as to

guarantee the safe running of devices and further

improve quality, reliability and thread loss.

4) Data and picture process and abnormal status alarm:

process in real time and analyze the gathered data and

picture signals to make it possible for the monitoring

terminals to observe the situation of measured points. If

abnormal cases happen, the system will recognize and

process picture and present warning automatically.

5) Service and charge management: in the master station,

PCs with high performance are in charge of service and

charge management. Check, calculate, store, analyze

and manage the electric data to know about the use of

customers accurately and timely. It not only makes it

convenient for customers to use, but ensures the legal

benefits of electric power departments.

B. Characteristics

This monitoring system has the following features:

1) It can directly use LV power line as transmission

medium which is from 35kV transformer substation to

1OkV MV distribution power line of user transformer or

from user transformer to user electric meters.

2) It can not only effectively reflect information of

electricity to monitoring master station, but enable

monitoring personnel to master operating status of

devices in monitoring sites with video and picture

straightly.

3) Integrated electric energy computation management can

be implemented to make it more systematized, scientific

and digital.

4) No extra power line is necessary to be deployed in this

system, and it has short cycle, low cost, high reliability

and nice quality of data transmission.

5) It effectively prevents illegal issues such as power-theft

or other impairments from happening.

6) Function of management is getting more perfect, thus,

much work handled by person is much more reduced,

and so are its bad effects.

7) Its installation is convenient, field proceeding project is

little and maintenance is easier.

V. CONCLUSIONS

To sum up, this system implements functions of real-time

monitoring users and burden forecast, which uses MV&LV

PLC as its transmission media with technologies of

communication, computer, automation and system

integration. So it is a synthesized system integrated with

power management and burden control, an important

technical means for realizing management of power grid

distribution and electric burden as well as for electric utilityto enter market to improve social and economic benefits. At

present, hardware and software designs of this system have

been completed, and the experimental units will be built in

Taiyuan in 2006. It is believed that, after the system becomes

popular in power systems, it will greatly facilitate external

services of electric enterprises and enhance internal working

efficiency, it will facilitate information development ofpower

systems as well as improve economic benefits and

management level of enterprises.VI. REFERENCE

[1] MIN Tao, "Joint Schemes of Electricity Energy Metering System and

Their Implementation", Power System Technology, August 2003, pp59-63.

[2] HU Xi-ling, "Design on the Software of Master Station of Automatic

Meter Reading System", YANTAI NORMAL UNIVERSITY JOURNAL

(NATURAL SCIENCE EDITION), vol.20 no.4, pp.268-271, 2004.

[3] LI Wen-jun, "Design and Implementation of Remote Reading System of

Water Meters", PROCESS AUTOMATION INSTRUMENTATION, vol.25

no.9, pp.54-57, 2004.

[4] ZHANG Kai, "A Discussion on Application Mode of Automatic Meter

Reading System", Power System Technology, May 2001,pp62-64.

[5] Gorge Jee, Con Edison. "Demonstration of the Technical Viability of

PLC Systems on Medium and Low Voltage Lines in the United States".

IEEE Communications Magazine, May 2003, pp 108-112.

[6] Daidclark, "Powerline communication [J]". Finally Ready for Prime

Time Computer, vol.15 no.6, pp.168-172, 1998.

VII. BIOGRAPHIES

Xu Zeng (1983-), male, master. His research interests include wireless

communication, power line communication and computer application. North

China Electric Power University. Tel: 010-51971471. Email:

zengxu666@163.com

Ming Liang (1956-), male. He obtained his ScD. degree in Electrical

Engineering and Information Technology from Vienna University of

Technology, Austria in 2002. He is currently a special-appointed professor in

College of Information Engineering at North China Electric Power

University (Beijing), managing director of ZBISI (Taiyuan ZHONGBO

Information Science Institute), chairman of CIEPT (Council of Information

Electric Power Technology), as well as vice-chairman of CAEPS (Council of

Automation for Electric Power System), China Society for Hydropower

Engineering (CSHE). His current research interests include wireless &power

line communication, and information electric power & computer techniques.

E-mail: lm@ncepu.edu.cn

Huaizhi Liu, male, Taiyuan Communication Network Management Office

of Beijing Military Area.

Yan Ren (1981-), female, master. Her research interests include wireless

communication, power line communication and Electric Power Information

Technology. North China Electric Power University. Tel: 010-51971471.

Email: renyanO3@163.com

Rui Yang (1986-), female, master. Her research interests include wireless

communication, power line communication and Electric Power Information

Technology. North China Electric Power University. Tel: 010-51971471.

Email: yangrui.010@163.com