Page 108 - From Smart Grid to Internet of Energy

Smart metering and smart monitoring systems Chapter 2 93

determine phase differences, frequency, ROCOF, power factor and similar
parameters. The time synchronization is ensured by GPS and satellite-based
time stamping that use coordinated universal time (UTC) to provide highly
accurate measurements. The smart grid infrastructure is comprised by large
penetration of RESs in addition to conventional sources and power plants.
Moreover, advances in power electronics and grid regulations have facilitated
integration of PEVs to utility network. Thus, a widespread utility network can
be illustrated as seen in Fig. 2.12 where RESs, transmission and distribution
lines, substations, and generation plants have been shown [23, 24]. Smart grids
are expected to be self-healing against power system faults and failures by sus-
taining its reliable operation capability to supply and distribute the generated
power. Although the utility networks are planned and installed in a resistant
structure to faults, the RES penetration and DERs affect the generation capacity
due to their intermittent structure. The RES integration may be performed at
transmission, distribution and even consumption levels. The utility network
requires to disconnect these integrations in any fault, failure or isolation condi-
tions to ensure healthy operation of grid. The dynamic system response is real-
ized when generators or loads rapidly react during grid disturbances. Therefore,
WAMPAC system should monitor the grid conditions and perform the required
operating procedures on demand. This protection scheme required a widespread
communication interface to transmit instant measurements and process the data
that are acquired from different distant locations. Since the smart grid infra-
structure requires large integration of RES and storage systems, the limits of
EMS and DMS systems will be forced to tolerate fluctuations of generation

FIG. 2.12 A smart grid infrastructure with RES penetration.