Power Line Communications

Principles, Standards and Applications from Multimedia to Smart Grid

Lutz Lampe, Andrea M. Tonello, Theo G. Swart, Lutz Lampe, Andrea M. Tonello, Theo G. Swart

• Publisher: Wiley
• Year: 2016
• Print ISBN: 9781118676714
• eBook ISBN: 9781118676776
• Edition: 2
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

This second edition of Power Line Communications will show some adjustments in content including new material on PLC for home and industry, PLC for multimedia, PLC for smart grid and PLC for vehicles. Additional chapters include coverage of Channel Characterization, Electromagnetic Compatibility, Coupling, and Digital Transmission Techniques. This book will provide the reader with a wide coverage of the major developments within the field. With contributions from some of the most active researchers on PLC, the book brings together a wealth of international experts on specific PLC topics.

1
Introduction

L. Lampe, A. M. Tonello, and T. G. Swart

Power line communications (PLC) reuse existing infrastructures (i.e. power lines) whose primary purpose is the delivery of AC (50 Hz or 60 Hz) or DC electric power, for the purpose of data communications. Hence, compared to the electric power ‘signal’, PLC uses high-frequency signals with frequency components starting from a few hundred Hz up to a few hundred MHz. The plurality of frequency bands used for PLC is related to different applications supported by PLC and their data-rate requirements, the specifics of grid topologies over which PLC is applied, as well as the ability of PLC technology to deal with the harsh communication environment. Before elaborating on this further, we first briefly review the terminology that has been used to describe PLC.

1.1 What is a Name?

Communication over power lines is referred to by different names that are often specific to the considered grid domain and application. The most commonly used terminologies are summarized in the following.

• Carrier-current systems: This term refers to the fact that carrier-modulated data signals are transmitted over power lines. It has often been used to collectively describe relatively narrowband signals with frequencies below 500 kHz. The Code of Federal Regulations, Title 47, Part 15, from the U.S. Federal Communications Commission (FCC) [1] defines carrier-current systems as ‘A system, or part of a system, that transmits radio frequency energy by conduction over the electric power lines.’
• Power line carrier: Similar to carrier-current systems, this is an early terminology used for systems that transmit carrier-modulated signals over power lines. A prominent example of its use is the ‘Guide to Application and Treatment of Channels for Power-Line Carrier’ by the ‘AIEE Committee on Carrier Current’ of the American Institute of Electrical Engineers (AIEE) [2], see also [3]. Also due to is earlier use, it typically refers to systems operating at frequencies below 500 kHz.
• Distribution line carrier (DLC): DLC refers to power line communication systems serving applications in the distribution domain. Due to the many line discontinuities and branches in the distribution grid, DLC systems face a more difficult communication environment than power line communication systems operating in the transmission segment of the power grid. DLC usually describes systems using frequencies below 500 kHz.
• Broadband over power lines (BPL): BPL is a more recent terminology that refers to systems operating in the frequency range of about 2 MHz to 30 MHz and beyond, with a signal bandwidth of tens of MHz and with data rates ranging from several Mbps to hundreds of Mbps; hence the term ‘broadband’. The application of BPL systems is mainly in the distribution part of the grid, to enable broadband access, as well as for in-home communication. ‘BPL’ is mostly used in North America. For example, the Subpart G of [1] is entitled ‘Access Broadband Over Power Line (Access BPL)’.
• Power line telecommunications (PLT): This term is used similar to BPL, but it is more popular in European countries. For example, the European Telecommunication Standards Institute (ETSI) produced numerous reports and specifications on ‘PLT’ through its ‘ETSI Technical Committee Power-Line Telecommunications (PLT).’

In this book, we understand and use the term ‘power line communications (PLC)’ as including all of the above, which has been widely accepted by now. For example, the leading scientific conference on the topic is the ‘International Symposium on Power Line Communications and Its Applications (ISPLC)’ [4], and the IEEE Communications Society has established the ‘Technical Committee on Power Line Communications (TC-PLC)’ [5]. To differentiate the various PLC technologies, reference [6] introduced a classification of PLC into ultra-narrowband (UNB) PLC, low data rate narrowband (LDR NB) PLC, high data rate narrowband (HDR NB) PLC and broadband (BB) PLC. We will discuss this further in the context of the historical development of PLC in the next section.

1.2 Historical Notes

Figure 1.1 illustrates the evolution of the PLC technology by identifying some early patents, specific application domains and international standards along a timeline.

Figure 1.1 Illustration of the evolution of PLC technology. *: BB PLC industry specifications were released in early 2000, e.g. [7]. The first HDR NB PLC systems were presented between 2001 and 2009 [8–10].

The origins of PLC can be traced back to the late 1800s and again in the early 1990s. Patents [11] and [12] consider remote meter reading via PLC (see [13]). The first description of remote load management using PLC, or so-called ripple control, is given in [14] (we note that [15] mentions the slightly earlier patent submission [16]). These ripple control systems (RCS) were developed further in the 1930s [17] and at a larger scale in the 1950s [18] to establish unidirectional communication for load management and other control functions in the power distribution grid. RCS use high-power and narrowband PLC signals. The signal frequencies are between 125 Hz and 3 kHz so that signals can pass through the distribution transformers and reach consumers. Before the widespread use of PLC via ripple control in the distribution domain, power line voice communication over medium-voltage and high-voltage transmission lines became popular in the 1920s [19]. These systems operate in the frequency range of about 15 kHz to 500 kHz and use signal bandwidths of a few kHz. Later, protective relaying has become a major application for these type of systems [20].

Two-way communication over power lines developed further in the 1980s with PLC systems designed for automatic meter reading (AMR) and automation in the distribution grid, as well as for industry and building automation [18, 6]. The deployment of these systems has been facilitated by the publication of the European Norm EN 50065 ‘Signalling on low-voltage electrical installations in the frequency range 3 kHz to 148.5 kHz’ in 1991.

All of the PLC systems mentioned so far fall under the classes of UNB and LDR NB PLC (see Figure 1.1). The former is defined as operating below 3 kHz and providing data rates of the order of 100 bps, while the latter operate between 3 kHz to 500 kHz with data rates of a few kbps [6]. This changed in the late 1990s, also since electric power utilities considered providing additional consumer services through their lines in the wake of the deregulation of the telecommunication and energy markets in Europe. Broadband PLC systems which use frequency bands between about 1.8 MHz to 250 MHz and provide data rates ranging from several Mbps to several hundred Mbps [6] were developed and deployed for Internet access and in-home multimedia applications. The introduction of BB PLC was accompanied by a surge in research activities, as can be seen from the first ISPLC¹ in 1997, related special issues in journals and magazines [22–26], books [27], and the founding of the IEEE Communications Society TC-PLC in 2004 (see Figure 1.1). Specifications for BB PLC systems were consolidated in the IEEE 1901 [28] and ITU-T G.9960/61 [29, 30] standards in 2010.

A second wave of innovation in the early 2000s shifted the focus back to NB PLC. With the ‘Smart Grid’ vision taking shape, it was natural for electric power utilities to consider PLC as a means to achieve an efficient and reliable communication infrastructure [6]. While NB PLC solutions have been available to provide, for example, basic AMR services, transmission methods successfully used in BB PLC were adopted for a new class of HDR NB PLC systems supporting between tens of kbps to about 500 kbps [6]. System specifications for HDR NB PLC have been published in the standards ITU-T G.9901-9904 [31–34] and IEEE 1901.2 [35] in 2012 and 2013, respectively. Smart grid applications have become one of the main drivers of innovation for both HDR NB and BB PLC, with publications (e.g. [6, 36, 37]) and conference sessions and panels dedicated to this topic.

Modern PLC systems use the latest signal processing techniques including advanced concepts such as multicarrier modulation with adaptive notching and multiple-input multiple-output (MIMO) transmission [38, 39], which have already been adopted in international standards [40] and industry specifications [41] (see Figure 1.1). This goes to show that the PLC technology of today is on a par with what is used for modern wireless communication and communication systems over other wired media. However, since PLC operates over ‘live wires’, there are distinct features to PLC technology not experienced for other media. An example is the efficient and safe coupling of signals onto and from power lines, which requires special considerations for instance through standards such as [42].

1.3 About the Book

Considering the above-outlined evolution of PLC over the past 100 or so years, as well as the fact that the PLC literature has been widely dispersed, the first edition of the book ‘Power Line Communications’ [43] was compiled with the objective of being a comprehensive single point of reference for researchers and practitioners either new to the field or already familiar with aspects of PLC. Since its publication in 2010, PLC has experienced important innovatio...

Table of contents

• Cover
• Title Page
• Copyright
• List of Contributors
• Preface
• List of Acronyms
• 1: Introduction
• 2: Channel Characterization
• 3: Electromagnetic Compatibility
• 4: Coupling
• 5: Digital Transmission Techniques
• 6: Medium Access Control and Layers Above in PLC
• 7: PLC for Home and Industry Automation
• 8: Multimedia PLC Systems
• 9: PLC for Smart Grid
• 10: PLC for Vehicles
• 11: Conclusions
• Index
• EULA