Page 136 - From Smart Grid to Internet of Energy

120 From smart grid to internet of energy

applications were related to remote meter reading and remote load manage-
ment, and the first two patents of PLC regarding these applications were avail-
able in 1898 and 1901 [11, 12]. Various applications related to measurement,
control and protection via power lines have been appeared after the patents,
and researchers have been widely focused on the applications over medium
voltage (MV) and high-voltage (HV) power lines. One of the most popular
applications was ripple control that was a load management system for protect-
ing and distribution of loads [13–15]. A ripple control system (RCS) was
enabled one-way communication with low data rates. It operated between
125 Hz and 3 kHz frequencies for passing signals over distribution trans-
formers. The most important disadvantage of the RCS was its high power
requirement. For instance, a few megawatts may be needed for data transmis-
sion. A number of important developments have been made for RCSs until the
1950s [15, 16]. The employed modulation schemes in these advanced systems
were amplitude shift keying (ASK) and frequency shift keying (FSK). Accord-
ing to utilizing digital modulation schemes, not only the high power require-
ments for data transmission was eliminated, but also higher data rates have
been obtained. Afterwards, at the beginning of the 1980s, several studies were
carried out to realize bidirectional PLC systems that were based on PLC systems
developed for automation and AMR applications [15, 17]. In 1984, Enermet
Melko was introduced as a bidirectional data transmission system that served
between frequencies of 3.025 and 4.825 kHz with phase shift keying (PSK)
modulation scheme. In 1990, Echelon introduced local operation networks
(LonWorks) system that was a networking platform. In addition, LonWorks
was built on a special protocol to meet control application requirements. The
frequency bands defined by International Telecommunication Union (ITU)
and the utilization of these bands in the PLC applications are illustrated in
the Fig. 4.1. The frequency bands are defined as super low (SLF), ultra low
(ULF), very low (VLF), low (LF), medium (MF), high (HF), very high
(VHF), ultra high (UHF), super high (SHF), extremely high (EHF) and tremen-
dously high frequency (THF), respectively.
The achievement of narrowband (NB) PLC systems supported the improve-
ment of broadband (BB) PLC systems that are principally aimed to be utilized
for internet service and home area network (HAN) applications. In 1997, the
primary internet applications that are related to internet access and service pro-
viding via PLC systems were introduced in Europe. However, the obtained
results were disappointing for the idea of internet access over the power lines.
Therefore, the interest was changed to home applications and industrial com-
munications in the early 2000s. Some industrial alliances such as the HomePlug
Powerline Alliance (HomePlug), Universal Powerline Association (UPA), High
Definition PLC (HD-PLC) Alliance, and The HomeGrid Forum have played
important roles in the acceleration of the process. In the last decade, various
standards have been defined to specify the implementations such as TIA-
1113, ITU-T G.hn, IEEE 1901 FFT-OFDM, and IEEE 1901 Wavelet-OFDM