Security analysis of Dutch smart metering systems - Multiple Choices

4.4 Port P3 4 PRACTICAL ANALYSIS
The smart meter communicates with a Data Concentrator (DC) which is typically located at
a local transformer substation. At the substation the medium voltage network is connected to
the low voltage “consumer” network. A DC is responsible for collecting the data of the smart
meters in the connected low voltage network. The data is communicated from the DC to the grid
operators network using IP or GPRS. A schematic overview of a PLC implementation can be seen
in figure 17.
Medium
Voltage
DC
Substation
Meter to data concentrator
CAS
GPRS
Internet
Low
Voltage
E G W
Electricity
Gas
Water
Figure 17: PLC smart metering implementation [22]
E G W
In this paragraph the communication between the smart meter and the DC will be discussed using
the 7 layers of the OSI model [37].
All devices using PLC communication must conform to the frequency allocation in CENELEC,
Frequency Band Allocation for Europe, defined in EN 50065-1 [14]. The IEC 61334-5 series
defines reliable mechanisms for transmission of data on a medium or low voltage transmission or
distribution system [21]. The smart meters which we encountered in the pilot projects use the
CENELEC A-Band (9-95kHz) and IEC 61334-5-1 [31] standard for the physical layer and the
media access control (MAC) section of the data link layer.
PLC uses a shared medium, all residences are connected to the same electricity network. Because
PLC signals weaken in strength when the distances increases, smart meters in residences can
repeat the signal from and to the DC so that larger areas up to approximately 700 meters can be
covered. The DC determines which meters will function as a repeater. Seven of these repeaters
can be setup in a chain which should enable the DC to reach even the most distant and most
difficult to reach meters, as shown in figure 18 for the Sagem implementation. In practice this
means that smart meters receive data from other meters enabling somebody to sniff metering data
of these meters.
Consumers are allowed to plug-in any device into the electricity network they like. One of the
downsides of the electricity network is that devices plugged into the electricity network can influence
the PLC signals that pass the network. From our contact at Delta we heard that an
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