英文文献-翻译-电能质量在线监测-科技类(电子-电气-自动化-通信.doc

外文文献翻译
目 录
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 POWER QUALITY MONITORING SYSTEM 10
1.3.1 Off-line Monitoring 10
1.3.2 On-line Monitoring 11
1.4 EVALUATION ON POWER QUALITY DATA TO BE TRANSFERRED 13
1.5 ANALYSIS BASED ON OPNET 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

1 外文文献翻译
1.1摘要
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。

关键词——电能质量，在线监测，通信网络，以太网，OPNET。
1.2介绍
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。
1.3电能质量监测系统
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。
(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。
1.4对电能质量数据传输的评估
电能质量测量并记录的主要指标有：
（1）电压偏离。
（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。
1.5基于OPNET的分析
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
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。

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。

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
表1 不同时间的后台通信量
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，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
1.6结论
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。
2 外文文献原文
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 devices, 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 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 predefined 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 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, 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 issues 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 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