英文文献 翻译 电能质量在线监测 科技类

外文文献翻译



1外文文献翻译
......................................................................................................................1


1.1摘要
...............................................................................................................................1


1.2介绍
...............................................................................................................................1


1.3电能质量监测系统
.......................................................................................................2


1.3.1离线监测
.............................................................................................................2


1.3.2在线监测
.............................................................................................................2


1.4对电能质量数据传输的评估
.......................................................................................3


1.5基于
OPNET的分析
....................................................................................................4


1.5.1共享式
10M以太网
...........................................................................................5


1.5.2交换式
10M和
100M以太网
...........................................................................6


1.5.3带后台通信量的交换式以太网
........................................................................7


1.6结论
...............................................................................................................................8
2外文文献原文
......................................................................................................................9


1.1 Abstract.......................................................................................................................9


1.2 INTRODUCTION......................................................................................................9


1.3 POWERQUALITYMONITORINGSYSTEM......................................................10


1.3.1 Off-line Monitoring...........................................................................................10


1.3.2 On-line Monitoring............................................................................................ 11


1.4 EVALUATIONONPOWERQUALITYDATATOBETRANSFERRED............13


1.5 ANALYSISBASEDONOPNET............................................................................14


1.5.1 Shared 10M Ethernet.........................................................................................15


1.5.2 Switched 10M and 100M Ethernet....................................................................16


1.5.3 Switched Ethernet with Background Traffic .....................................................17


1.6 CONCLUSION ...................

........................................................................................18



外文文献翻译



电能质量是电力工业的一个重要指标，影响到电力企业和用户的利益。本文介绍了
电能质量监测的功能和方法，讨论了在线监测对电能管理的重要性，并着重介绍了电能
质量在线监测系统通信网络的要求，分析了不同的通信网络在应用电能质量在线监测系
统时的性能，用
OPNET模拟器证实了这些分析。结果显示共享式
10M以太网不能满足电
能质量在线监测的要求，需要交换式的
10M以太网或者比其更好的网络。


——电能质量，在线监测，通信网络，以太网，
OPNET。

近年来，电能质量受到了电力公司和用户的普遍关注。如果电能质量超过了某一界
限，就回危及到电力系统里设备运行的安全性和稳定性，影响到消费者和电力企业的经
济利益。人们颁布了一些电能质量标准，例如
EN50160。我国从
1990到
2000年陆续颁
布了
5条电能质量标准，对其质量指标进行定义和规定，例如电压偏移，频率偏移，谐
波，三相电压不对称，电压波动和闪变。随着现代工业的迅猛发展，越来越多非线性负
荷进入电力系统，例如电力电子装置。这极大地恶化了电能质量，电能质量的监测变得
迫切和重要。电能质量监测不仅仅测量和记录电能质量指标，帮助查找污染源，还为采
取措施提高电能质量提供的必要信息。

人们对电能质量监测的理论和应用做了很多努力，包括电能质量指标的定义，衡量
方法，软硬件的设计，和整个电能质量监测系统的构建，设计了一些专门的电能质量监
测仪，它们都能适合在电力系统中在线或者离线的监测。许多监测仪能够利用高精度的
电子部件，例如
DPS，FPGA，实现实时并行处理数据。此外传统的傅里叶分析，微波分
析也可以在这些装置中使用，用来识别瞬时的电能质量问题。为了把远程的电能质量监
测仪的数据传输到监控中心，人们采用了多种的通信电路。

然而，大多数的电能质量监测仪都是有限制或者预定函数的，提升这些仪器的性能
意味着成本上升，而把原始数据传输到电能质量监测中心进行高级的或者扩展的电能质


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量分析显得更加优越。因此，主要问题是通信网络是否能够承担这个任务。

本文首先对离线和在线电能质量监测系统进行了比较，并指出构建在线监测系统的
优点和重要性，接着分析了在线监测系统的通信要求和结构。为了利用目前的电力系统
的通信网络，本文研究了以太网传输简单原始数据的应用。
OPNET是一个专业的通信网
络模拟器，它将

为我们提供不同以太网在电能质量监测系统中的性能的虚拟分析。


现在主要有两种主要的电能质量监测形式：离线监测和在线监测。


1.3.1离线监测
电力企业可以派遣员工带着电能质量监测仪，定期的或者不定期的到监测点测量。
这种方法主要针对的分电站和客户，可能持续几个小时或者几周。这种方法今天还在广
泛使用，但有很多缺点。测量的结果受到测量地点和时间的极大限制，很难获得整个系
统的全面信息。因此，不可能评估整个系统的电能质量，很难获得足够的信息作进一步
的分析和决定，如查找污染源，为提高电能质量提出最佳解决方案。


1.3.2在线监测
我们都知道电能质量与其他产品质量不同。它是由电力生产商和消费者共同决定的。
实际上许多电能质量问题是由用户的电器引起的。此外，电能质量指标在不同的空间时
间也有所不同，他们随着地点和时间而改变。为了得到准确和系统的电能质量信息需要
长时间连续的观测，获得实时的数据。因此，建立电能质量在线监测系统比偶尔进行的
一些测量更加好。目前有几种电能质量在线监测系统。

电能质量在线监测系统由以下几部分组成：


(1)电能质量监测仪。它们能引用监测点的电能质量监测仪的数据，负责测量三相
电压和电流，提供基本的电能质量指标，把测量得到的数据通过通信电路传输到电能质
量监测中心贮存、显示和进一步的分析。
(2)电能质量监测中心。电能质量监测中心负责从监测点的电能质量监测仪收集和
贮存数据，执行更高级的功能，例如数据分析和数据输出。电能质量监测中心常由数据
服务器和几个工作站组成。

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(3)通信电路或者通信网络。通信电路把电能质量监测仪和电能质量监测中心连接
起来。通信电路可以使用各种的通信类型，如电话线、电力线载波、移动通信系统、微
波通信、以太网、光纤网络。为了利用现时的电力通信网络，首选以开放式传输协议为
基础的局域网和广域网。在线监测系统比传统的离线监测更具优点，使电力企业和用户
共同受益。然而，目前的系统也有以下缺点：
(1)功能有限。它仅能够提供一些电能质量指标，很难拓展他们的功能，如评估瞬
时电能质量问题。
(2)许多装置都是以计算机为基础和多功能的装置太昂贵，难以在工作站大规模使
用。
(3)仅能够测量和记录电能质量指标，由于通信和存储的限制，极少传输原样数据，
这就限制了数据的交流和更高级的电能质量监测功能。
随着电能质量对国民经济的影响逐渐加大和人们对电能质量研究的逐步深入

，人们
需要更多的电能质量信息。一种趋势是运用更高性能的硬件提高站点监测装置的数据加
工能力，如出现了
DSP和
MCU结合，
FPGA的应用。另一种趋势就是利用目前的通信系统，
如以太网和光纤系统，通过装置间的数据交换和调和，达到更高的数据分析和判断的目
的。随着人们需要的电能质量指标越来越多，整个系统必然要有原始数据传输的能力，
这样更先进的功能，例如故障改组和污染源的鉴定在监测中心很容易附加或拓展。总的
来说，未来的电能质量在线监测系统应满足以下要求：

（1）优秀的实时测量能力。它应能够识别静态的和瞬时的电能质量问题。
（2）强大的通信能力。这使整个系统实现数据共享和调和，使系统功能拓展成为可
能。
（3）先进的开放式协议传输系统。这使电能质量监测系统能够利用目前的通信网络
降低成本，并容易统一的归并到电力企业目前的信息管理系统中。
电能质量测量并记录的主要指标有：

（1）电压偏离。

外文文献翻译


（2）频率偏移。
（3）谐波。这些指标包括三相谐波电压和电流、调和比、总谐波失真。
（4）三相电压不平衡度。三时序电压基本原则的信息，即正序、负序和零序电压也
合适。
（5）电压波动和闪变。这些指标有电压波动，短期的闪变和长期的闪变。
（6）电能质量监测系统包括监测中心和监测仪。为了获得电能质量的指标，人们用
电能质量监测仪，通过数字或对等的方法测量三相电压和电流。例如，当采用交流电取
样技术的时候，每个电压和电流都从相等的组距和间隔时间取样，抽样数据用来计算。
目前
50赫兹的电力系统取样频率为
6400赫兹或者更高，这就意味着在
20毫秒内需要
128或者更多的数据点。在站点工作的监测仪，通过通信电路把数据传输到监控中心。
这些数据可以是原样数据或者电能质量指标。为了降低贮存和通信的条件，原样数据极
少传输或者记录。
假设电力质量监测仪抽取三相电压和电流的样本，从每个对等的输入电路中，采用
每周波
128点的采样速率，每个样本数据
2字节。那就是说电能质量监测仪
20毫秒传
输
6*128*2=1536字节，数据传输速度为
1536*50*8=614400bps。如果电能质量监测系统
里有
10台监测仪，那么整个通信电路数据流达到
6144000bps。

如此庞大的数据传输对传统的电力通信电路来说，是一个很沉重的负担或者说是不
可完成的任务。然而，为了进行更高级的电能质量分析功能，如污染源鉴定，人们渴望
获得原样样本数据。随着电力通信技术和下部结构的进步，旧的高压电力线载波系统

被
现代的通信网络逐渐代替，如以太网和光纤系统，这样的通信网络能够满足此要求吗
?

以工业以太网为例，本文研究了在电能质量监测系统中传输原样样本数据的可能
性，并利用
OPNET模拟器提供数据分析和虚拟图解。



OPNET是在通信网络模拟和分析方面最好的专业工具之一。它为使用者提供了面对
对象的设计技术和图形编辑界面，还有很多强大的编辑器，如网络编辑器，节点编辑器
和过程编辑器。它能够用来建立通信网络模型，完成网络分析任务，并且提供大量的网
络设计模型，几乎支持所有的网络技术。


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用
OPNET模拟以以太网为基础的电能质量监测系统，如图
1所示。

这个电能质量监控系统包括
10台监测仪。我们在第三部分讨论的同等条件下，总
的数据流达到约
6Mbps，还没有考虑结构控制字节的情况。这和
10M的以太网的最大传
输能力接近。因此，我们分析了
10M和
100M以太网的通信性能。


图
1.以以太网为基础的电能质量监测系统模型


1.5.1共享式
10M以太网
共享式
10M以太网就是以太网里的所有设备共享
10M的通信电路。当
6Mbps数据流
的电能质量监测系统采用共享式
10M以太网时，以太网网络延迟如图
2所示。从图上我
们可以看出随着时间的增长，以太网的延迟时间急剧变长，这就暗示着网络堵塞，不能
很好的工作。图
3显示了以太网通信的比特误差率，这证实在通信中发生转换误差。

这个结果表明共享式
10M以太网不能满足电能质量监测系统的要求。


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图
2.共享式
10M以太网的网络延迟


图
3.共享式
10M以太网的比特误差率


1.5.2交换式
10M和
100M以太网
交换式
10M以太网能为每
2台通信设备提供
10Mbps的通信电路，整个通信速度比
10Mbps更加高。当使用
10M或者
100M交换式以太网的时候，网络延迟如图
4所示。从
图可以看出
10M交换式以太网的延迟时间约为
4毫秒，
100M约为
0.4毫秒，小而且稳定。
这暗示了网络工作正常。交换式
10M和
100M以太网都满足电能质量监控系统的通信要
求。在交换式以太网中
6Mbps的原始数据流的传输是能够实现的。


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图
4交换式以太网的网络延迟


1.5.3带后台通信量的交换式以太网
我们该紧记电力通信网络中的以太网不是仅为电能质量监测系统服务的，它还同
时提供其他的通信服务，例如数据采集和监视控制，继电保护。下面本文研究以太网带
后台通信下的性能，后台通信是相对电能质量监测数据流来说的。假设在不同的时间存
在大小不等的后

台通信量，如表格
1


时间（
s）后台通信量
0~14 0
15~29 1,000,000
30~44 2,000,000
45~60 3,000,000

当存在后台通信，
10M和
100M以太网的网络延迟如图
5所示。从图中可以看出随着
后台通信量增加，
15和
30秒内网络延迟增加很少，以太网还工作。但
45秒之后，当后
台通信量扩大到
3,000,000bps时，
10M以太网堵塞，不能正常工作。而
100M以太网从
开始一直正常工作。这结果说明交换
10M以太网看起来足够承担电能质量监测的任务，


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但当以太网同时提供其他服务时存在着风险。当构建或设计一个电能质量监测系统时，
通信网络中所有可能的数据流都应该详细的分析和考虑。


图
5带有不同后台通信量的交换式以太网的网络延迟


本文介绍了电能质量监测的功能和方法，讨论了电能质量管理在线监测的重要性。
然后集中介绍了电能质量在线监测系统的通信要求。

在
OPNET模拟器的帮助下，本文还研究了不同的以太网传输电能质量数据时的性能。
从分析中得出，为了传输原始样本数据，电能质量在线监测系统应采用交换式
10M的以
太网或者比其更好网络。


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1.1 Abstract
Abstract-Power quality is an important index of the electricalindustry, and it affects the
interests of both power utilities andcustomers. This paper introduces the functions and
methods of power quality monitoring, and it discusses the importance of on-line monitoring
for power quality management. Then the paper focuses on the demand for the communication
network of power quality on-line monitoring system, and it analyzes the performance of
different communication networks of power quality on-line monitoring system, and OPNET
simulator is used to validate the analysis. Result shows a shared 10M Ethernet couldn’t fulfill
the demand of power quality on-line monitoring, and a switched 10M Ethernet or better is
required.1.

Keywords-Power quality, on-line monitoring, communication network, Ethernet, OPNET

1.2 INTRODUCTION
Recently power quality receives wide attention by both power producer and customer [1-3].
If the power quality excesses certain limits, it will endanger the safety and stability of power
equipments operating in the power system, and affects the economical interest of power
utilities and customers. Several power quality standards have been published, such as
EN50160 [3-5]. In China, five power quality standards are published from 1990 to 2000, they
define and regulate several power quality indexes, such as voltage deviation, frequency
deviation, harmonics, three-phase voltages unbalance, voltage fluctuation and flicker[6]. With
the rapid development of modern industry, more and more non-linear loads, such as power
electronics devic

es, come into the power system. It deteriorates the power quality dramatically,
and power quality monitoring becomes urgent and important. Power quality monitoring can
not only measure and record power quality indexes of them power system, helping locate
supervise pollution sources, but also provide necessary information for taking measures to
improve power quality. Much effort has been taken to investigate the theory and application
of power quality monitoring, including the definition of power quality index, measurement

9


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method, hardware and software design, and architecture of whole power quality monitoring
system (PQMS). Several kinds of power quality monitoring instruments have been designed,
and they are applied to power system for off-line or on-line monitoring [7-9]. Many of these
instruments make use of high-performance hardware, such as DSP and FPGA, to achieve
real-time parallel processing of data [10-11]. Besides traditional Fourier analysis, wavelet
analysis is now used in these devices to identify transient power quality problems [12-14]. To
transmit data from remote power quality monitoring instrument (PQMI) to power quality
monitoring center (PQMC), various communication channels are adopted [13-15]. However,
most PQMIs have limited or pre-defined functions, and the improvement of.PQMI’s
performance always means increasing of cost. It would be preferable that the original
sampling data could be transferred to the PQMC for advanced or extend power quality
analysis functions. The major problem is whether the communication network could

undertake the task. This paper first compares the performances of off-line and on-line power
quality monitoring systems, and points out the advantage and importance of constructing
on-line monitoring system. Then it analyzes the communication requirements and
architectures of on-line monitoring system. Taking advantage of the present power system
communication network, the paper investigates the application of Ethernet for original
sampling data transmission. OPNET, a professional communication network simulator, is
used to provide visual analysis for the performance of various Ethernets in power quality
on-line monitoring system.

1.3 POWER QUALITY MONITORING SYSTEM
Nowadays there are mainly two kinds of power quality monitoring: off-line monitoring and
on-line monitoring.

1.3.1 Off-line Monitoring
The power utilities can send workers with power quality monitoring instruments
periodically or non-periodically to perform on-site measurements. This is usually done for
some major substations or customers, and it could last for a few hours or weeks. This


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method is widely used today, but it really has many disadvantages. The measurement results
are greatly limited by the position and time of performing measurements, and it is difficult to
acquire overall information

of the system. As a result, it is impossible to evaluate the power
quality of the whole power system, and it is difficult to acquire enough information to carry
on advanced analysis and decision, such as locate pollution sources and propose best
solution to improve power quality.

1.3.2 On-line Monitoring
As we know, power quality is different from the quality of other products. It is not only
determined by power producers, but also determined by the customers. In fact, it is the
equipments of customers that cause many power quality problems. Furthermore, power
quality indexes are different from space to space, and from time to time, so it changes as the
location and time change. To get accurate and systematic information of power quality, it is
necessary to perform long-time continuous measurement, to acquire real-time data.

As a result, it is better to construct a power quality on-line monitoring system than carry on
some measurements now and then. Nowadays there come several power quality on-line
monitoring systems. A power quality on-line monitoring system consists of the following
parts:

Power quality measurement instrument (PQMI). It refers to the power quality measurement
instrument work on site. It measures the three-phase voltages and currents, and provide basic
power quality index. The data are then transferred through communication channels to power
quality monitoring center (PQMC) for storage, display and further analysis.

Power quality monitoring center (PQMC). PQMC gathers and stores data from remote
PQMI, and perform other advanced functions, such as data analysis and data export. Data
server and several workstations are usually required in a PQMC.

Communication channel or network. The communication channel connects the PQMC and
PQMI. It could use any kind of communication types, such as telephone line, power line
carrier, mobile communication system, microwave communication, Ethernet, fiber channel,


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etc. In order to make use of the present power system communication network, LAN and
WAN that base on open protocols are preferred.

The on-line monitoring system shows their advantage over traditional off-line monitoring,
and benefits both power utilities and customer. However, the present systems have the
following shortcomings:

They have limited functions, and could only provide a few power quality indexes. It is
difficult to extend functions, such as evaluating transient power quality problems.

Many devices are based on PC and such multi-function devices are too expensive to be
used on site in a large scale.

They can only measure and record power quality indexes, and they seldom transfer original
sampling data because of communication and storage restrictions. This limits the data
exchange and realization of more advanced power quality monitoring functions.

With the development of research on power quality issue

s and increasing influence of
power quality on economics, there is increasing demand for more power quality information.
There is a trend to apply high performance hardware to improve the data process capability of
on-site monitoring devices. The combination of DSP and MCU and the application of FPGA
are reported. Another method is to make use of the present communication system, such as

Ethernet and fiber system, to achieve high data analysis and judgment performance by data
exchange and coordination among devices. As more and more power quality index are
required, it is necessary to have original data transfer capability for the whole system, so that
more advanced functions, such as fault reorganization and pollution source identification, can
be easily added or extended in the monitoring center. In summary, the future power quality
on-line monitoring system should satisfy the following requirements:

Excellent real-time measurement capability. It should able to identify both static and
transient power quality problems.

Powerful communication capability. This will benefit the coordination and data share


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among the whole system, and make it possible for extending functions.

Advanced and open-protocol system. The PQMS can take the advantage of the present
communication network to reduce cost, and it can be easily integrated into the present
information management system of power utilities.

1.4 EVALUATION ON POWER QUALITY DATA TO BE TRANSFERRED
The major power quality indexes to be measured and recorded are:

Voltage deviation.

Frequency deviation.

Harmonics. These indexes include three-phase harmonic voltages and currents, harmonic
ratio (HR) and total harmonic distortion (THD).

Three-phase voltage unbalance. The information of three sequence fundamental voltages,
i.e., positive-sequence, egative-sequence and zero-sequence voltages are also

preferred.

Voltage fluctuation and flicker. These indexes include oltage fluctuation, short-term flicker
and long-term flicker.

The power quality monitoring system includes monitoring center and monitoring
instruments. To obtain the power quality indexes, three-phase voltages and currents are
measured by power quality monitoring instruments with digital or analogue methods. For
example, when ac sampling technique is adopted, each voltage or current is sampled at equal
interval per period, and the sampled data points are used for calculation. At present, the
sampling frequency is 6400 Hz or higher for a 50Hz power system, which means 128 or more
data points are acquired in 20ms. The monitoring instruments work on site, and they transfer
data through communication channels to the monitoring center. The data transferred could be
original sampling data power quality indexes. In order to reduce the requirements for storage
and communication, the original sampling data are seldom transferred

or recorded.


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Suppose a power quality monitoring instrument samples three-phase voltages and
three-phase currents, and it samples 128 data points per period for each analogue input
channel, and each sampling data is represented by 2 bytes. Then the PQMI transmits
6*128*2=1536 bytes every 20ms, and the data transmission speed is 1536*50*8=614400 bps
(bit per second). If there are 10 monitoring instruments in a PQMS, the whole data flow
comes to 6144000 bps Such amount of data transfer may be a heavy burden or impossible
task for some traditional power communication channels. However, in order to perform
advanced power quality analysis functions, such as pollution source identification, it is
desirable to obtain original sampling data. With the advance of power communication
technology and infrastructure, the old high-voltage power line carrier systems are replaced by
modern communication networks, such as Ethernet and fiber system, could the present
communication network fulfill such a demand? Taking an industrial Ethernet as an example,
the paper investigates the possibility of transfer original sampling data in power quality
monitoring system, and OPNET simulator is utilized to provide statistic analysis and visual
illustration.

1.5 ANALYSIS BASED ON OPNET
OPNET is one of the best professional tools for communication network simulation and
analysis. It supports the object-oriented technology and graphic edit interface for users. There
are a lot of powerful Editors, such as Network Editor, Node Editor and Process Editor. It can
be used to build communication network model and perform network analysis. It provides
large amount of models for network devices and supports almost every network technology. A
power quality monitoring system based on Ethernet can be modeled by OPNET, as shown in
Fig.1.

This PQMS includes 10 PQMIs. Under the same condition as discussed in Section III, the
total data flow comes to about 6Mbps even when the frame control bytes are not considered.
This is close to the maximum transfer capability of a 10M Ethernet. For this reason, the
communication performance of both 10M and 100M Ethernet are analyzed.


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Fig.1. PQMS model with Ethernet

1.5.1 Shared 10M Ethernet
A shared 10M Ethernet means all the equipments in the Ethernet share the 10Mbps

communication channel. When shared 10M Ethernet is adopted for the PQMS with

about 6Mbps data flow, the Ethernet delay is shown in Fig.2. It could be seen that the

Ethernet delay increases dramatically as time goes, which indicates the network

actually jammed and couldn’t work properly. Fig.3 shows the bit error rate of Ethernet

communication, which confirms that sever transfer errors occur during communication.

The results reveal that a shared 10M Ethernet couldn’t fulfill the demand of PQMS.


Fig.2. Ethernet delay of shared 10M Et

hernet


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Fig.3 Bit error rate of shared 10M Ethernet

1.5.2 Switched 10M and 100M Ethernet
A switched 10M Ethernet could provide 10Mbps channel for every two equipments that
communicate, and the whole communication speed could be much higher than 10Mbps.
When a switched 10M or 100M Ethernet is used, the Ethernet delay is shown in Fig.4.
It could be seen that the delay of 10M Ethernet is about 4ms, and the delay of 100M
Ethernet is about 0.4ms, which are small and stable. This indicates the networks work
properly. Both switched 10M and 100M Ethernet can fulfill the communication
requirements of PQMS. The transfer of original data that flows at about 6Mbps can be
realized in switched Ethernet.


Fig.4 Ethernet delay of switched Ethernets


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1.5.3 Switched Ethernet with Background Traffic
It should be bare in mind that the Ethernet in the power communication network doesn’t
serve solely for power quality monitoring system. It has other communication tasks, such as
SCADA and relay protection, to serve at the same time. Next the paper investigates the
performance of Ethernet when it has other communication traffic, which called background
traffic comparing to power quality monitoring data flow. Suppose there exist different amount
of background traffic at different time as shown in Table I.

TABLE I BACKGROUND TRAFFIC AT DIFFERENT TIME

Time (second) Background traffic (bps)
0~14 0
15~29 1,000,000
30~44 2,000,000
45~60 3,000,000

When the background traffic exists, the Ethernet delay of 10M and 100M Ethernet is shown
in Fig.5. For the 10M Ethernet, it could be seen that the Ethernet delay increases slightly as
background traffic increases after 15 seconds and 30 seconds, but the Ethernet still works. But
after 45 seconds, when the background traffic exceeds 3,000,000 bps, the 10M Ethernet is
jammed and couldn’t work properly. As to the 100M Ethernet, it works well all the time.

The result illustrates that although a switched 10M Ethernet seems sufficient for power
quality monitoring task, it has some risks when the Ethernet should also serve other
applications. When a power quality monitoring system is being designed or constructed, all
the possible data flow in the communication network should be considered and analyzed
carefully.


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Fig.5 Ethernet delay of switched Ethernets with various background traffic

1.6 CONCLUSION
The paper introduces the functions and methods of power quality monitoring, and it
discusses the importance of on-line monitoring for power quality management. Then the
paper focuses on the demand for the communication of power quality on-line monitoring
system.

With the help of OPNET simulator, the paper investigates the performance of different
Ethernets for power quality data transfer. From the analysis, in order to transfer original
sampling da

ta, a switched 10M Ethernet or better is required for power quality on-line
monitoring system.