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外文资料翻译 PLC Studies in China as a Contribution to the Development of International StandardsAbstractIn the field of PLC, the standardization process on international level is progressing very slowly. The EMC Laboratory of the North China Electric Power University has received the task to develop a measurement method for the field radiated by PLC installations and a standard to be used in the future for the regulation of the PLC deployment. After a short introduction of the standardization process at international level, the paper presents measurements performed at the North China Electric Power University of radiated fields due to PLC. Comparisons of the field with various limits are shown. Finally the paper also presents a review of the regulatory situation on international level.Keywords: PLC, standardization, electromagnetic disturbances.1. IntroductionIn the last 6 to 7 years, feasibility studies have been performed in various countries to check the possibility of using the low voltage distribution network to provide data transmission and eventually also telephonic links to individual customers at frequencies up to 30 MHz. This new technology is called Power Line Communication (PLC). This application is particularly interesting for power utilities which, on one side can enter in this way the telecommunication market and use their network for power network data transmission, on the other side can use this technology to control their own network. However, this transmission mode in the frequency band extending from 1.6 to 30 MHz presents various and quite complex EMC problems. The main problem isproduction of disturbances in the network and in the environment.2. Disturbance sourcesThe sources of disturbance are both radiated and conducted:- the emission of electromagnetic noise which can interfere with radio communications for safety or military use, or disturb the radio amateurs；- conducted differential and common mode currents can penetrate in any equipment connected to the network in which PLC is working. The disturbances have two types of origins:- the signal source asymmetry, due to the coupler asymmetry；- the unbalance of the Low Voltage Distribution Network (LVDN) and as a result an common mode to differential mode conversion.The conversion from differential to common mode due to the networkunbalance has been analysed in various paper, as for instance in 1. Different mitigation solutions have been also been proposed in the literature , but the research work must be further continued. 3. Standardization at international levelConcerning EMC problems, at an international level, two types of standards must be developed:- a product standard；- a network standard.3.1 The product standardThe product standard should be an amendment of the CISPR22 standard and is the task of the Subcommittee CISPR. A first idea was to extend the concept of Longitudinal Conversion Loss (LCL) specific for symmetric telecommunication pairs of wire to the non symmetric power network.Measurements performed in various power networks, as those shown in Fig. 1, have given a large spread of LCL values .It was not possible to arrive to a consensus for the concept based on the LCL value, to be used for the calculation of a voltage limit at the ports of the equipment connected to the network, although that this concept has been well-established for the case of telecommunication lines. After about 4 years of work and a whole series of documents at CD (Committee Draft) stage, the concept did not find the requested qualified majority for approval by the CISPR/I/ although that it found majority approval within the working group. It was decided to re-start the work evaluating a new basis. A New Work Item Proposal (NWIP) was prepared by the French national Committee and approved in April 2005 6. The work will not be focused any more on the LCL value, but will try to: - describe the typical electricity installations where it is intended to connect PLC equipment；- identify the potentially disturbed services/equipment for each typical section of electricity installations described above；- assess the level of protection currently provided by the CISPR22for each equipment/service；- set radiated and conducted limits for emissions of each typical section of electricity installation when PLC is operating.The work started in June 2005 and is currently in progress.3.2 Network standardThe European Commission has issued in 2001 the Mandate 313 which gives CENELEC and ETSI the task to develop a standard, to define emission limits for all communication networks including PLC.Different limits have been proposed by various countries (Germany, UK, Norway) and entities (CENELEC, FCC, BBC). The differences between the various proposals were quite large and it was not possible to reach a consensus. A Joint Working Group ETSI/CENELEC has produced several drafts, which have all failed to be approved by the National Committees.4. PLC activity at the North China Electric Power University 4.1 Mandate given to the EMC LaboratoryIn China, the Telecommunication Center of the China National Power Grid is supervising the PLC deployment over the whole country as a provider of service, but not as a regulatory authority. The Telecommunication Center has given to the EMC Laboratory of the North China Electric Power University the mandate to develop:- a measurement method for the field；- a standard which should be used in the future as a basis for the regulation of the PLC deployment. These studies are a contribution, together with other research activities in Europe like the European Project OPERA, to the development of international standards.4.2 Experimental measurementsIn order to simulate the PLC operation environment, an experimental network was set up. Its structure is presented in Fig. 2. As seen in Fig.2, the field was measured with a loop antenna which gives the magnetic field value. The conversion to electric field was performed by multiplying the measured values by the vacuum impedance (377 ohms). It is clear that in near fields, the value of the vacuum impedance is higher than 377 ohms and a better approach to convert magnetic to electric fields in such configurations is under study.As a pair of PLC modems with rate of 200Mbps being used to download data from internet, the radiated field was also measured and shown in Fig.4. The radiation field was above all of the three limits. The dimensions of the room were 9.456.8m. Three power distribution branches have been installed in the test. The first branch supplied three daylight lamps； the second branch a high-powered air conditioning； the third one five household electric appliances, including a refrigerator, a computer, a microwave oven, a washer, and a TV set each of it at distances of 10 meters. PLC signals were coupled at the outlet of the energy meter. A loop antenna was placed 3 meters away from the power line.A PLC router and PLC modems composed of the LAN at nominal rates of 14Mbps, 45Mbps and 200Mbps to simulate the PLC internet access have been used. An example of the radiated electric field measured in the room is presented in Fig.3.When using the PLC modems, besides shutting them down and transferring data with the internet at relatively high rate, there is another possible state: standby. In this state, the PLC modem is powered on, but it isnt used to transfer data by the customer. The radiated field of a pair of PLC modems with a rate of 45Mbps in standby state was also measured and shown in Fig.5. Compared with the background, it appears that the radiation of the PLC network is significant when the PLC modem is in standby especially from 18MHz to 23MHz.Fig.6 shows the measured radiation fields with different load conditions. The dotted line presents the condition when all household electric appliances were on, and the solid line presents the “off” condition. Fig.6 shows that the radiation fields did notvary significantly when the household electric appliances were “on” and “off”.Another interesting item investigated at the North China Electric Power University EMC Laboratory was the relation between the injected current and the radiation field strength. Generally, if this relation is known and it if is stable enough, then we can assess the emission level to some extent by measuring the injected current. Therefore, the injected current was measured in parallel with the field. Fig.7 shows the relation between the injected current and the radiation field in the frequency domain for the 45Mbps network. A rather good correlation was found except for frequencies in the range of about 16 to 24 MHz. The quantitative transfer relation for a typical network structure is still under investigation.5. Regulatory approaches for access networks in Europe and USA5.1 European Union regulationThe Communication Committee (COCOM) of the European Commission (EC) has delivered a positive message on the Draft Recommendation on Broadband Communications from 6 April 2005. This recommendation is very similar to the “Report and Order” published by the FCC on October 14, 2004. The main features of this recommendation are:- It requires that Regulatory Authorities should not follow the ex-ante approach for PLC deployment and operation. That means that PLC equipment should have easy market access and that an authorization is only required in case of harmful interference within a specific location at a specific frequency；- the PLC equipment is regarded as a telecommunication equipment and as a consequence should follow the CE certification；- it requires that PLC systems should be installed and operated according to good engineering principles；- it recognizes the right of countries to take special restriction measures if necessary, for instance frequency restrictions in specific areas (military, coast where ship navigation can be affected), or fir frequencies of specific use (fire alarm).Misunderstandings by EU member states are minimized by the recommended permanent dialogue towards the EC.5.2 USA regulationAs an amendment to Part 15 of its rules, the Federal Communication Commission (FCC) has published on 14 October 2004 the “Report and Order”, which defines the BPL (Broadband Power Lines, name of PLC in US) regulation for Access PLC.Access BPL systems will operate on an unlicensed non-interference basis under Part 15 model. This means that the permitted limits are those defined by FCC Part 15, i.e.62 dBV/m (see Fig. 3) and that the FCC will ask for a decrease of these limits or mitigation measures only in case ofInterference. In addition, in order to achieve this goal the “Report and Order” specifies that the FCC: - can decide that BPL must avoid specific frequencies and can decide to shut down any unit in the case of harmful interference；- establishes “exclusion zones” in locations close to sensitive operations, such as coast guard or radio astronomy stations, within BPL must avoid operating on certain frequencies；- establishes consultation requirements with public safety agencies, federal government sensitive stations and aeronautical stations；- establishes a publicly available Access BPL notification database to facilitate an organized approach to identification and resolution of harmful interference；- changes the equipment authorization for Access BPL systems fromverification to certification； - improves measurement procedures for all equipment that use RF energy to communicate over power lines.6. ConclusionThe Power Line Communication represents a very promising technique,permitting to extend internet, voice phone and digital TV everywhere where exists a Low Voltage Distribution Network. However, a few EMC problems should still be solved, in order to avoid disturbances.On international level, the standardization work is progressing very slowly, due to many divergent approaches and lack of some technical solutions. The measurements performed in the experimental network of the EMC.Laboratory of the North China Electric Power University, show that the radiated fields are related with the work state and the transfer rate of the PLC modems. Especially for the higher rate, the radiated fields are beyond limits of NB30, ITU K60 and even FCC Part15. The research work performed in this university, together with studies taking place in other universities in the world, will contribute to a better understanding of the behavior of the reducing the disturbances and to permit the development of standards compatible with the commercial interests and with the protection of consumers.AcknowledgmentThis work is supported by the National Natural Science Foundation of China (project 60571030).国际标准的发展促进国内PLC的研究摘要在该领域的PLC ，标准化进程，国际一级的进展十分缓慢。 EMC的实验室，华北电力大学收到了任务，制定一个测量方法，为外地辐射装置用PLC和标准，用于在今后的监管的PLC部署。经过简短介绍的标准化进程在国际一级，提出了测量数据进行的华北电力大学的辐射领域，由于PLC的。比较外地的各种限制显示。最后，文件还提出了审查监管情况，国际一级。关键词： PLC ，标准化，电磁干扰。1 .导言在过去6至7年，可行性研究已经完成在不同国家，以检查是否有可能利用低压配电网络，使数据传输和电话联系，最终也对个人客户的频率高达30 MHz的。这一新技术被称为电力线通信（ PLC ）的。这种应用是特别有趣的是电力，一方可以以这种方式进入电信市场，并利用其网络，电力网络的数据传输，另一边可以使用此技术来控制自己的网络。然而，这种传输模式中频段从6月1日至30兆赫的各种礼物和相当复杂的电磁兼容问题。主要的问题isproduction的网络中的干扰和环境。2 .干扰源干扰的来源都是辐射，并进行：-排放的电磁噪声，可干扰无线电通讯的安全或军事用途，或干扰无线电业余爱好者；-进行差分和共模电流可以穿透任何设备连接到网络中，公司正在努力。骚乱有两种类型的来源：-信号源的不对称，由于耦合不对称；-不平衡的低压配电网（ LVDN ） ，因此一个共同的模式，以差模转换。转换差别的共同模式由于网络不平衡分析了各种文件，例如在不同的解决方案已经缓解还提议在文献，但研究工作必须进一步继续。3 .标准化在国际一级关于电磁兼容问题，在国际层面上，两种类型的标准，必须制订：-产品标准；-网络标准。3.1产品标准产品标准应修改CISPR22标准的任务是小组委员会的CISP。第一个想法是的概念扩大纵向转换损耗（柜）具体对称双丝电信的非对称电网。表现在各种测量电力网络，因为这些显示图，给予了大量的传播拼箱值。这是不可能达成协商一致的概念基础上拼箱值，用于计算的电压限制在港口的设备连接到网络，但这个概念已经被确立为案件电信线路。经过大约4年的工作和一系列文件光盘（委员会草案）阶段，这一概念没有找到所要求的合格的多数批准的CISPR /我/虽然，它发现了多数人的赞同在工作组内。这是决定重新开始新的工作评价的基础。一项新的工作项目提案（ NWIP ）是由法国国家委员会，并核准于2005年4月这项工作将无法集中更多的拼箱价值，但将努力：-描述了典型的电力设施的地方是连接PLC设备；-确定潜在的不安服务/设备为每个典型部分电力设施上文所述；-评估的保护水平，目前提供的CISPR22为每个设备/服务；-建立辐射和排放量进行限制，每一个典型的电力安装一节时， PLC的运行。这项工作开始于2005年6月，目前正在取得进展。3.2网络标准欧盟委员会已经于2001年发布的任务313使CENELEC和ETSI的任务是制定标准，确定排放限值的所有通信网络，包括PLC的不同的限制提出了不同的国家（德国，英国，挪威）和实体（ CENELEC ，催化裂化，英国广播公司） 。之间的分歧的各种建议是相当大，因此无法达成共识。 联合工作组的ETSI / CENELEC编制了若干草案，这都没有得到批准的全国委员会。4 . PLC的活动在华北电力大学4.1授权的电磁兼容实验室在我国，电信中心，中国国家电网公司是监督部署对整个国家作为一个供应商的服务，而不是作为一个监管机构。电信中心已考虑到电磁兼容实验室的华北电力大学开发的任务：-一种测量方法的领域；-一个标准的，应在将来使用，以此为基础的PLC部署。这些研究的贡献，连同其他研究活动在欧洲象欧洲项目歌剧，向国际标准的发展。4.2实验测量为了模拟PLC的经营环境，实验网络正式成立。其结构如图2 ，实地测量的环形天线使磁场价值。转换电场是由乘以测量值的真空阻抗（ 377欧姆） 。显然，在不久的领域，其价值的真空阻抗高于377欧姆和更好的方法来转换磁场对电场在这种配置目前正在研究。作为一个对PLC的调制解调器的速度200Mbps被用来从互联网下载数据的辐射场也是衡量和显示在图4 。辐射场是最重要的三个限制的尺寸为9.45 房间六点八米，三峡电力分配部门已经安装测试。第一个分支提供三个日光灯；第二处高功率的空调；第三个五年家用电器，包括冰箱，电脑，微波炉，洗衣机和一台电视机，在每一个距离10米。 PLC的信号，再加上出口的电能表。循环天线被置于3米远离电力线。PLC与PLC调制解调器路由器组成的局域网的名义利率14Mbps ， 45Mbps和200Mbps模拟PLC的互联网接入已经使用。一个例子辐射电场测量室介绍图。当使用的PLC调制解调器，除了关闭他们失望和传输数据与互联网在相对较高的利率，还有一个可能的状态：待命。在此状态下， PLC的调制解调器的电源，但它不是用来传输数据的客户。辐射场对PLC的调制解调器的速度45Mbps在待机状态也是衡量和图5所示。与背景，似乎辐射的PLC网络具有重要意义时， PLC的调制解调器在待机特别是从达18MHz到23MHz 。图6显示了测量辐射领域不同负载条件下。虚线提出的条件时，所有的家用电器上，而实线介绍了“关闭”状态。图6表明，没有辐射领域差别很大时，家电是“上”和“关闭” 。另一个令人感兴趣的项目调查，在华北电力大学电磁兼容实验室是关系注入电流和电场强度的辐射。一般来说，如果这种关系是已知的和稳定的，如果是不够的，那么我们可以评估排放水平在一定程度上通过测量注入电流。因此，注入电流测量平行与外地。图7显示之间的关系注入电流和辐射场的频域的45Mbps网络。一个比较良好的相关性，发现除了频率范围约16至24兆赫。转让的数量关系的一个典型的网络结构仍在调查之中。5 .管理办法的接入网络在欧洲和美国5月1日欧洲联盟条例通信委员会（巴统）的欧洲委员会（ EC ）带来了一个积极的信息对建议草案的宽带通信从2005年4月6日。这项建议是非常类似的报告“和秩序”出版由FCC于2004年10月14号。主要特点，这一建议是：-它要求监管当局不应按照事前办法PLC的部署和行动。这意味着，公司设备应具有方便的市场准入，并授权只须在案件内的有害干扰的具体位置在特定的频率；-的PLC设备被视为电信设备，因此应遵循CE认证；-它要求PLC系统应安装和操作按照良好的工程原则；-它承认各国有权采取特别限制措施，如果有必要，例如频率限制在特定领域（军事，海岸船舶航行可能受到影响） ，或飞行情报区的具体使用频率（火灾报警） ，误解了欧盟成员国尽量减少长期对话的建议对欧共体。5.2美国监管作为修正案的第15部分的规定，联邦通讯委员会（ FCC ）发表了关于2004年10月14 “报告和秩序” ，它确定了电力线宽带（宽带电力线，名称的PLC在美国）规例获取PLC的。电力线宽带接入系统将在一间无牌经营不干预的基础上根据15模型。这就是说，允许限额所规定的FCC Part 15的， ie62 dBV /平方米（见图3） ，并要求联邦通信委员会将减少或减轻这些限制措施只能在案件干涉。此外，为了实现这一目标“报告和秩序”中指定的催化裂化：-可以决定BPL公司必须避免特定频率和可以决定关闭任何单位的情况下有害干扰；-建立“禁区”的地点接近敏感的业务，如海岸警卫队或射电天文站，必须避免在电力线宽带业务在某些频率；-建立磋商要求公众安全机构，联邦政府的敏感和航空站；-建立了一个公开的访问BPL的通知数据库，以促进一个有组织的方法来识别和解决有害干扰；-改变了设备的授权，电力线宽带接入系统核查验证；-提高了测量程序，对所有设备的能源使用射频通讯电力线路上。6 .结论电力线通讯是一个非常有前景的技术，允许延长互联网，语音电话和数字电视在世界各地存在着一种低压配电网。但是，有少数的EMC问题，仍然应该得到解决，以避免干扰。在国际一级，标准化工作进展非常慢慢地，由于许多不同的办法和缺乏一些技术解决方案。测量完成实验网络的EMC实验室华北电力大学，表明，辐射相关领域的工作状态和传输速率的PLC调制解调器。特别是较高的利率，辐射领域超出限度NB30 ，国际电联K60 ，甚至催化裂化Part15 。这项研究工作在这所大学，研究一起发生在其他大学在世界上，将有助于更好地理解的行为减少了干扰，并允许制定标准兼容的商业利益与保护消费者的利益。致谢这项工作得到了国家自然科学基金资助项目（项目六千零五十七点一零三万） 。
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