Power Line:
control and
communication
Sistemi e strumenti per l'automazione, A. Flammini, AA2011-2012
Phasor mesurement
A given sinusoidal signal
x(t ) = ak cos(kω0t ) + bk sin(kω0t ) = ak2 + bk2 cos(kω0t + φ )
and its phasor
ak2 + bk2 jφ
1
(ak − jbk )
Xk =
e =
2
2
Signal
Sistemi e strumenti per l'automazione A. Flammini, AA2011-2012
Phasor
1
Phasor Measurement Unit
60 samples per cycle
Anti-aliasing filter
GPS to synchronize PMUs samples
and to generate a servo clock
60 samples per cycle
DFT analysis:
•Synchronous/asynchronous
sampling
•Separation of fundamental
harmonic
Analog Input
N samples
Phasor
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Anti-aliasing
filters
Modem
GPS
receiver
Phase locked
oscillator
16 bit A/D
converter
Phasor
microprocessor
2
PMU on Power Line
Distributed synchrophasor measurements
wider view of the power system will require synchronized phasor
measurements
control to voltage instability prediction
transient stability monitoring
PMU in primary substation
PMU data
Timestamped phasor are collected
concentrator
Their use is under study
Optimal placement of PMUs
in power systems to enhance
state estimation is a problem
that needs to be solved
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
Primary
substation
H/M
Secondary
substation
M/L
PMU
H/M
M/L
PMU
M/L
3
Smart Meter
What is a smart meter
A new electricity (and not also) meter which can eliminate many
labor-intensive business process
Availability of power using information in every hour, or even in
every second (typically every 15 minutes)
Bidirectional communication (data and commands)
The part of Advanced Metering Infrastructure ( AMI )
Smart metering is not only
electricity, but also gas,
water and heat
Sistemi e strumenti per l'automazione A. Flammini, AA2011-2012
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Smart Metering
Why smart metering:
Decrease power wasting caused by meter
Greenhouse effect
Economize power by change our way in using power
•real-time registration of the consumes
•possibility to read the meter both locally or remotely
•remote limitation of the
throughput through the meter,
even cessation of the utility if
necessary
•interconnection with other
networks in order to display and
collect data
•control smart appliances
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Microgrid communications
Data transmission between meter and collector
wired
•PLT (Power Line Transmission): IEC61334,
ANSI/IEA 709.1/2, LonWorks (Echelon C.),
PRIME (STMicroelectronics), G3-PLC (Maxim),
IEEE P1901.2
•BPL (Broadband Power Line communication)
IEEE 1901, HomePlug Green PHY
•M-bus (EN 13757-1/2/3)
wireless
Smart
meter
Data
collector
Smart
meter
Smart
meter
•IEEE 802.15.4
•ZigBee Smart Energy Protocol
•Wireless M-bus
…secure in any case (privacy)
Sistemi e strumenti per l'automazione A. Flammini, AA2011-2012
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State of Art
Italy: 1st large smart meter deployment. Telegestore Project installed
more then 30 million of new smart meters since 2005.
New legislation (direttiva MID 204/22/EC) will force to replace all
old gas meter with smart gas meter, final version of legislation is
being defined.
UK: Many smart gas sensors have already been placed in past. Now
the legislation is leading the utility (and costumer) to replace both
electricity and gas meter for all costumers.
USA: California are leading smart meter market in USA.
Until 2006, 9 million of meter was retrofitted with microprocessor.
Great investments on AMI.
China: As of 2011, SGCC (State Grid Corporation of China) has
installed 36 million smart meters and announced it will install over
300 million smart meters by the end of 2015
Sistemi e strumenti per l'automazione A. Flammini, AA2011-2012
7
Advanced Meter Infrastructure
AMI
AMM
AMR
AMI component
AMR (Automated Meter Reading): based on smart metering.
Collects data from smart meters. Take care about the
communication between meters and concentrator.
AMM (Automated Meter Management): allows bidirectional
communication in the smart meters network. This remote
management performs sending of commands and messages to the
meters and is able to download data.
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
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AMI features
Metering
system
platform
Exchange
Infrastructure
meter
concentrator
GSM/GPRS
Industrial
Metering
meter
WL/PLC
Residential
Metering
Infrastructure of metering systems
Automates most of the metering centred repetitive activities
Collects granular consumption data to deploy dynamic pricing
mechanisms
New payment and customer service options
Control of electrical load within the home and or businesses to
improve system diversity
Technology
Platform
meter
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Open Metering System (OMS)
Hierarchical architecture
•AMM (Automated Meter Management): processes metering data
for billing and balancing
•MUC (Multi Utility Communication): collects, analyzes and
processes data from meter
•METER / ACTUATOR: provides data to the system
AMM
Tertiary
Communication
MUC
METERS
MUC
MUC
MUC
Primary
Communication
Note: a secondary communication has been planned for repeater
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OMS: Communication Levels
Primary Communication (among MUC dev. and meter)
•Wired: M-bus wired (EN 137571/2), pull mode
•Wireless: wM-bus (EN 13757-4),
MUC
push mode (only T1/2
e S1/2 allowed)
•PLC (Power Line
Communication) future option
Secondary Communication
MUC
repeater
•Communication range extension
Tertiary communication (among
AMM end MUC dev.)
AMM
•TCP/IP v.4 or higher
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
meter
meter
MUC
11
OMS: Application Layer
Primary Communication (close to the meter)
•M-bus data coding (EN13757-3) :
-DIF (Data Information Field), data representation and length.
-VIF (Value Information Field), representation unit and multiplier of the value.
Optional field Extension (DIFE and VIFE).
•DLMS/COSEM (Device Language Message Specification/ COmpanion
Specification for Energy Metering; IEC 62056 ): communication entity
definition and data format. Structured data form
•SML (Smart Message Language) Sym2 project, german standard of electricity
communication data. Can be encapsulated in other protocol (TCP/IP, M-bus).
COSEM can be integrated in SML protocol
Tertiary communication
•DLMS/COSEM
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M-bus Standardization
M-bus is typically used for metering applications. This standard is
defined in EN 13757 (Communication system for meter and remote
reading of meters)
•EN 13757-1. Data Exchange: base communication between meters and central
data collector; A view of communication system
•EN 13757-2. Physical and data link layer: physical specification for wired data
transmission; Transmission protocol data description
•EN 13757-3. Application layer: application protocol for compatibility of different
producer product
•EN 13757-4. Wireless meter readout (868MHz – 870MHz SRD band): wireless
M-bus communication. Physical and Data link
•EN 13757-5. Relaying: range extension; repeater
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M-bus
Wired bus communication, distance between slave and repeater up to 350 m
Remote powering of the slaves: 1->36V and 0->24V
Segmentation: repeaters allow to separate zones
Cable: two-wire standard telephone cable
From 300 to 9600 baudrate at 350 m length, in standard realization and
maximum of 250 slaves
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M-bus: telegram format
· Single Character
This format consists of a single character and
serves to acknowledge receipt of transmissions.
· Short Frame
This format with a fixed length besides the C
and A fields includes the check sum (this is
made up from the two last mentioned
characters), and the stop character 16h.
· Long Frame
With the long frame, after the start character
68h, the length field (L field) is first transmitted
twice, followed by the start character once again. After this, there follow the function field (C
field), the address field (A field) and the control information field (CI field). The L field gives the
quantity of the user data inputs plus 3 (for C,A,CI). After the user data inputs, the check sum is
transmitted, which is built up over the same area as the length field, and in conclusion the stop
character 16h is transmitted.
· Control Frame
The control sentence conforms to the long sentence without user data, with an L field from the
contents of 3. The check sum is calculated at this point from the fields C, A and CI.
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
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M-bus: field meaning
L-field: length of the packet without L and CRC fields
C-field: control frame field, function field. Identify the type of
frame (SEND, CONFIRM, REQUEST, o RESPOND). The
function field specifies the direction of data flow, and is
responsible for various additional tasks in both the calling and
replying directions
A-field: address field. The address field serves to address the
recipient in the calling direction, and to identify the sender of
information in the receiving direction. The size of this field is one
Byte, and can therefore take values from 0 to 255
CI-field: packet header, specify data type in the application data
payload
Check Sum: 2 bytes control frame
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
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wM-bus
SubGHz frequency band (868MHz – 869MHz)
2-FSK modulation
Manchester or 3 out of 6 encoding
Up to 66.66 kbit/s
Packet length up to 256 bytes
M-bus implements 1,2 and 7 ISO/OSI stack layers
One way (T1, S1) or bidirectional (T2, S2) communication
Typically meter starts communication
Data coding:
•M-bus codification (EN13757-3):
•DIF (Data Information Format); VIF (Value Information Format)
COSEM/DLMS (EN13757-1), mandatory for tertiary communication:
•OBIS (Object Identification System) structured data
AES-128 encryption
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
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wM-bus: type of communication
Type
Directivity
description
S1
Unidirectional
In stationary mode, the metering devices send their
data several times a day. The data collector may save
power as meter send a wake up signal before
transmission
S1-m
Unidirectional
Same as S1 but collector can not enter in power save
mode
S2
Bidirectional
Bidirectional version of S1
T1
Unidirectional
In the frequent transmission mode, the metering
devices periodically send their data to collector.
Interval in the order of several seconds or minutes
(faster, less power consumption)
T2
Bidirectional
Bidirectional version of T1. The data collector may
request dedicated data from the metering devices
R2
Bidirectional
The frequent receive mode permits multiple metering
devices not to interfere due to frequency multiplexing
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wM-bus: cycle of communication
S2: meter periodically sends its data
T2: meter periodically starts a
communication cycle
In the unidirectional
version only Data
Collector transmits
R2: meter periodically listens channel
waiting for a preamble
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wM-bus: telegram format
WL packet structure
optional block to add to telegram related to message length
L-field: length of the packet without L and CRC fields
C-field: control frame field. Identify the type of frame (SEND, CONFIRM,
REQUEST, o RESPOND)
M-field: producer code field. http://www.dlms.com/flag/INDEX.HTM
A-field: address field. 6 bytes unique address for each
CI-field: packet header, specify data type in the application data payload
CRC: 2 bytes control frame
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ZigBee Smart Energy Profile
ZigBee smart energy profile components:
•Metering device
•Energy service interface
•In-premises display device
•Programmable Communicating Thermostat Device
•Load Control Device
Non
•Range extender device
ZigBee
Energy
link
•Smart appliance device
service
interface
•Prepayment terminal device
AMI
server
ZigBee
link
ZigBee
link
In home
display
ZigBee
link
Home Energy
Management
Console
ZigBee
link
meter
Smart
Appliance
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
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ZigBee Smart Energy Profile
2.4 GHz and subGHz channel frequency band (IEEE 805.15.4)
Client/server communication model
•The data exchanged depend on the scenario
Security: AES-128 encryption; APS encryption
UTC time representation for data
•resolution down to second
Synchronization one time at day
Tunneling protocol (provisionary and not certifiable)
•DLMS/COSEM
•IEC61107
•ANSI C12
•M-bus
•Climate Talk
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ZigBee Supported Features
Basic metering [measurements, historical info, etc], Text messages
Demand Response (DR) and Load Control
Pricing [multiple units & currencies, price tiers, etc.]
Device support for Programmable Communicating Tstats (PCTs), Load
Control Devices, Energy Management Systems, In Home Displays (IHDs), etc.
Security to allow consumer only, utility only, or shared networks
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Power Line Communication
PLC (Power Line Communication) is technology of information
transmission on power line cables
Information signal travels on cable with power signal (50/60 Hz)
Reduction of cables installation (electrical cables are already placed)
Noise introduced by powered devices on network is problematic
Band over 30 MHz is not allowed for electromagnetic emissions
NarrowBand PLC (up to 500kHz)
•LonWorks (widely used thanks to Enel)
•PRIME
•G3-PLC
•IEC61334, ANSI/IEA 709.1/2 (not OFDM)
BroadBand BPL (MHz)
•HomePlug
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
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PLC Regulations
CENELEC Bands Narrowband():
•A Band (3 kHz-95kHz): reserved to
electrical utilities (under license)
•B Band (95 kHz-125kHz): for all
applications without protocol
•C Band (125kHz-140kHz): reserved to
home network systems, Access Protocol
(CSMA / CA = Carrier Sense Multiple
Access /Collision Avoidance) mandatory.
•D Band (140 kHz-148.5kHz): alarm and
security system without protocol
International
Regional
National
Higher narrowbands (up to 500kHz)
seem to be open by new regulation
Broadband is not regulated
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PRIME
PRIME (PoweRline Intelligent Metering Evolution): open, public and
non-proprietary telecom solution focused on smart metering and smart grid
PRIME Alliance: Advance Digital Design, Current Technologies
International, Iberdrola, Landis & Gyr, ST Microelectronics, Usyscom,
ZIV Medida
Define low layers of a PLC narrowband data transmission system
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PRIME: System Architecture
PRIME system is composed of subnetworks, each of them defined in the context of a
transformer station. A subnetwork is a tree with two types of nodes, the Base Node
and the Services Nodes
•Base Node
The Base Node is at the root of the tree and acts as master node that provides
connectivity to the subnetwork. It manages the subnetwork resources and
connections. There is only one Base Node in a subnetwork.
•Service
Service Node
Any other node of the subnetwork is a Service Node. Each of these nodes is one
point of the mesh of the subnetwork. These nodes have two responsibilities:
connecting themselves to the subnetwork and switching the data of their neighbors in
order to propagate connectivity.
Service
Node
Base
Node
Service
Node
Service
Node
Power line
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PRIME Stack Layers
The service-specific Convergence Sublayer (CS)
classifies traffic associating it with its proper MAC
connection. This layer performs the mapping of any
kind of traffic to be properly included in MAC
SDUs. It may also include payload header
suppression functions. Multiple CSs are defined in
order to accommodate different kinds of traffic into
MAC SDUs.
The MAC layer provides core MAC
functionalities of system access, bandwidth
allocation, connection management and topology
resolution. It has been defined for a connection
oriented Master-Slave environment, and optimized
for low voltage power line environments.
The PHY layer transmits and receives MAC
PDUs between Neighbor Nodes. It is based on
OFDM multiplexing in CENELEC A band and
reaches up to 130 kbps raw data rate.
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PRIME: Physical Layer
OFDM (Orthogonal Frequency Division Multiplexing) modulation
Subcarriers all contained in CENELEC A band (3kHz – 95kHz)
Up to 96 subcarriers
Modulation adopted: Differential Phase Shift Keying (DPSK) in
different implementations: DBPSK, DQPSK, D8PSK
Optional FEC (Forward Error Correction)
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PRIME: Frame Format
Preamble: The use of OFDM symbols for the Preamble is not
appropriate. Additionally, the preamble needs frequency agility to
avoid that frequency selective attenuation could suppress it
Header: just after the Preamble, 13 pilot subcarriers are inserted in
each of the first 2 OFDM symbols to provide enough information to
estimate the sampling start error and the sampling frequency offset
Payload: DBPSK, DQPSK or D8PSK encoded, depending on the
SNR available to achieve the desired BER. The MAC layer will select
the best modulation scheme using information from errors in the last
frames. The system will then configure itself dynamically to provide
the best compromise between throughput and efficiency in the
communication. This includes deciding whether or not FEC
(convolutional coding) is used.
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PRIME: MAC Layer
Each node have 48 bits Mac address
Master/Slave configuration oriented
Medium access is both Time Division Multiplex (TDM) and
CSMA/CA
•SCP: Base Node allocation needed
•CFP: Free access to medium
Type of connection
•Unicast
•Broadcast
•Group-based multicast
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
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G3-PLC
G3-PLC: Maxim, Iberdrola, EDF, eRDF, Itron, Texas Instruments
Define low layers of a PLC narrowband data transmission system
ARCHITECTURE
Decentralized architecture, where the data concentrator acts as an
application relay, with more or less autonomy. The exchanges at transport
level in this case are limited to the dialogue between the meters and the
concentrators
Or to have a more centralized architecture in which the concentrator
simply acts as a network gateway and the meters dialogue directly with
servers.
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G3-PLC Stack Layers
The Metering application covers layers 5 to 7 in
the OSI model. It will be noted that all these
applications rely natively on UDP, but there is
nothing to prevent the future introduction of
Applications that use TCP.
The 6LoWPAN adaptation sublayer enables an
efficient interaction between the MAC and the IPv6
network layers.
The MAC sublayer based on IEEE 802.15.4; and
the Adaptation layer based on RFC 4944:
Transmission of IPv6 Packets over IEEE 802.15.4
Networks (6LowPan).
The PHY layer transmits and receives telegrams
between nodes. It is based on OFDM multiplexing
in CENELEC A band.
6LoWPAN is widely used also in wireless to have IPv6 over IEEE802.15.4
(e.g. ISA100)
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G3-PLC: Physical Layer
OFDM (Orthogonal Frequency Division Multiplexing) modulation
Carriers frequency band in CENELEC A band (3kHz – 95kHz), but
also up to 180kHz (out of CENELEC up to 490kHz)
Up to 36 subcarriers
Modulation adopted: DBPSK, DQPSK
Up to 34.1kbit/s
FEC (Forward Error Correction)
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G3-PLC: Telegram Format
Ack frame and data frame format
Preamble:
used for synchronization
FCH (Frame Control Header):
control information for demodulation
Data:
Information transmitted with maximum length of 252 symbols
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PRIME and PLC G3 (supported by IEEE1901.2)
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PRIME and PLC G3 (supported by IEEE1901.2)
G3, more powerful FEC
PRIME, less complex FEC
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LonWorks
LonWorks (Local Operating Network): network platform developed
by Echelon Corp., based on neuron chip
Enel Telegestore project communication based on LonTalk ,
LonWorks communication protocol
60 million devices by 2006
Open protocol standard from 2009 (ISO/IEC 14908-1)
Each LonWorks device must have single ID (sold by Echelon)
Multiple standards
•International and open industry standard
•European standards
•China national standards
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LonWorks: Neuron Chip
Protocol Firmware
(Layer 1-2)
Protocol Firmware
(Layer 3-6)
Media Access
CPU
Network
CPU
RAM / ROM
EEPROM
RAM / ROM
EEPROM
Transceiver
Comm
port
Optional
External
Memory
I/O (Counters,
Resources,
Drivers, etc)
I/O
Conditioning
RAM / ROM
EEPROM
Application
CPU
Xtal
Power
Regulator
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
Neuron Chip
Node Specific
Program
39
LonTalk Protocol
Media
•Twisted pair, powerline, radio
frequency, fiber optics, coaxial cable
•Lowest data rate 610 bps
Reliability
•Supports end-to-end acks with ARQ
•Broadcast acks also
Medium access
•Proprietary collision prediction
algorithm
•Collision detection on some media
(e.g., TP)
•Optional priority feature
Network management/applications
SNVTs
•Standard Network Variable Types
•A key to interoperability
•Standardizes variables used to name
and describe things and their states
•Maintained by LonMark International
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LonTalk: Network Layer
LonTalk protocol support a variety of topologies
LonTalk protocol support physical layer repeaters as well as store
and forward repeaters to repeat packets from one channel to another.
The protocol also supports bridges to repeat all packets on the bridge’s
domain from one channel to another
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LonTalk: Data Link and Physical Layer
DATA LINK
Error Detection (CRC)
Flexible allocation of bandwidth
Priority access mechanisms
Graceful behavior under overload
•p-persistent CSMA
Message collision avoidance
Optional collision resolution, collision detection
PHYSICAL
FSK modulation
Manchester encoding
Spread spectrum (proprietary) or narrowband
10 Kbps, Up to 2000 m on clear line
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
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HomePlug
HomePlug Alliance: STMicroelectronics, Maxim, Marvel, SONY
BPL (Broadband Power Line communication)
standard from 2010 (IEEE 1901)
HomePlug version:
•HomePlug 1.0, 14 Mbit/s
•HomePlug AV, 200 Mbit/s
•HomePlug AV 2, 600 Mbit/s – 1.8 Gbit/s
•HomePlug Green PHY, 10 Mbit/s; designed for smart metering
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
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HomePlug: System Architecture
Fondamenti di elettronica digitale, A. Flammini, AA2011-2012
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HomePlug: Physical Layer
Windowed OFDM
•Spectral notching for preamble, frame control and payload
•917 carriers (excluding Amateur bands)
Bit-loaded modulation: BPSK, QPSK, 16 QAM, 64 QAM, 256
QAM, 1024 QAM
•Optimum adaptation for each connection
Turbo FEC for frame control, beacon, payload
•16, 136 and 520 byte block sizes respectively
•Near capacity performance (1/2 dB from Shannon Capacity)
Channel interleaver for impulse noise and other PL impairments
Diversity coding for reliable frame control, beacon and ROBO
HP1.0 coexistence mode uses 1.0 frame control
•AV preamble can be detected by 1.0 devices
200 Mbps PHY channel rate
•150 Mbps PHY information rate
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HomePlug: MAC Layer
Network managed by a Central Coordinator (CCo)
Three access methods within a network:
•Beacon: Non-contention, CCo transmits Beacon in dedicated slot
•CSMA: Contention-based, exchange of priority-based user data
and management messages, shared with HP 1.0
•Contention-free: Only designated station transmits. QoS
guarantee
•Beacon Period is divided into “Regions”
Schedules specified in Beacons
•Different allocations are further specified in some Regions
•Beacon Period synchronous with AC line cycle
Allocations: persistent, or non-persistent (valid for current Beacon
Period only)
Neighbor network coordination
•Sharing channel with other AV networks (MDUs)
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