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Informatik 7
Rechnernetze und
Kommunikationssysteme
Smart Grid Standards
Dr.-Ing. Abdalkarim Awad
13.01.2016
Some Smart Grid Related Standards
IEC 61850 and DNP3: Substation
IEC 61698/61970: Transmission and distribution
IEC 61400: Wind Turbines
IEEE 37.118: PMU
OpenADR: Automated Demand Response
ZigBee: Home Automation
BACnet: Building Automation
Dr.-Ing. Abdalkarim Awad 2
Distributed Network Protocol DNP3
DNP3 becomes IEEE 1815
Set of communication protocols between data acquisition and control equipment
It plays a crucial role in SCADA systems
Used by control centers, RTU and IEDs
It has five layers
Master/slave
Originally the physical layer used serial communication, but now Ethernet can be
found
Dr.-Ing. Abdalkarim Awad 3
user
Application
Transport
Data Link
Physical
IEC 61850: Substation
IEC: International Electrotechnical Commission
Communication Networks and Systems in Substations
Was developed to provide inter-operability intelligent electronic devices (IEDs) for:
Protection, Monitoring , Control and automation in substations
Addresses Communications and Information modeling
Dr.-Ing. Abdalkarim Awad 4
IEC 61850 primary parts
Part 6-1: Substation Configuration Language (SCL)
Part 7-2: Abstract Communications Service Interface (ACSI) and base types
Part 7-3: Common Data Classes (CDC)
Part 7-4: Logical Nodes
Part 8-1: Specific Communications Service Mappings (SCSM) -MMS & Ethernet
Part 9-2: SCSM -Sampled Values over Ethernet
Part 10-1: Conformance Testing
Dr.-Ing. Abdalkarim Awad 5
Three IEC61850 Protocols
MMS (Manufacturing Message Specification)
GOOSE (Generic Object Oriented Substation Event)
SV (Sampled Values)
Dr.-Ing. Abdalkarim Awad 6
The Power Substation
Dr.-Ing. Abdalkarim Awad 7
The Power Substation
Dr.-Ing. Abdalkarim Awad 8
Circuit Breaker (CB)
Intelligent Electronic Device (IED)
Microprocessor-based controllers of power system equipment
e.g. circuit breaker, protective relay...
Receive digitalized data from sensors and power equipment
Issue control commands in case of anomalies to maintain the desired status of power grid
e.g. tripping circuit breakers
Dr.-Ing. Abdalkarim Awad 9
Example
Dr.-Ing. Abdalkarim Awad 10
IEC 61850 Standard in Substation Autmation
Dr.-Ing. Abdalkarim Awad 11
Sampled Values
GOOSE
MMS
Example
Dr.-Ing. Abdalkarim Awad 12
Source:
https://www.pacw.org/issue/winter_2008_issue/protection_goose/high_performance_iec_61850_goose_and_protection_relay_t
esting.html
Industrial Ethernet Network
Dr.-Ing. Abdalkarim Awad 13
Prioritization
In IEC 61850 control applications, it is required that the control message transfers occur within 3 ms.
Faults can produce a data message storm.
Strict priority.
Dr.-Ing. Abdalkarim Awad 14
Generic Substation Events (GSE)
Generic Substation Events (GSE)Control model defined in IEC 61850
Provides a fast and reliable mechanism of transferring event data over the complete substation networks
Multicast
GSE subdivided intoGOOSE (Generic Object Oriented Substation Events)
GSSE (Generic Substation State Events).
SV (Sampled Values)
Dr.-Ing. Abdalkarim Awad 15
GOOSE: Generic Object Oriented Substation Event
GOOSE messages are sent when event occurs
Publisher/Subscriber model
Ethernet message (not TCP/IP)
Multicast and priority tagging
To guarantee delivery, GOOSE message is sent several times
No ACK
Examples of GOOSE messages :
- Autoreclosing (between relay and BCU/CB)
- Intertripping (between relay and relay)
- Blocking (between relay and relay/BCU)
- Interlocking (between BCU and BCU)Dr.-Ing. Abdalkarim Awad 16
Sampled Values
Similar to GOOSE
Transmits high speed streams of data set samples encoded in multicast or unicast Ethernet frames.
The protocol uses a publisher/subscriber model, in which a publisher transmits unacknowledged data to subscribers.
Periodic (4000 sample per second)
Dr.-Ing. Abdalkarim Awad 17
Communication Stack of IEC 61850
Dr.-Ing. Abdalkarim Awad 18
Ethernet Link Layer (with Priority, VLAN)
GOOSESV SNTP
TCP/IP
MMS
TCP/IP
Time Critical
Ethernet 100 MB/s Fiber
GOOSE and SV messages
Application layer directly accesses link layer for speed – no TCP/IP
Uses Ethernet frame directly with Priority/VLAN 802.1Q tag
Use priority ≥4 due to criticality or messages.
VLAN use is optional.
Fields in payload - source ID, status bits, analog values, time stamp, sequence number, time to live, quality bits, test modes.
Typical packets 200 – 300 bytes long.
Dr.-Ing. Abdalkarim Awad 19
Preamble DA SA 1Q tag Type Payload FCS
TPID PCP DEI VID
12 bit 3 bits 1 bit 12 bit
TPID: Tag Protocol Identifier
PCP: Priority Code Point
DIE : Drop Eligible Indicator
VID: VLAN identifier
Drivers for Wide Area Monitoring
To avoid large area disturbances
To improve usage of existing power transfer capacity
To secure power system integrity
20Dr.-Ing. Abdalkarim Awad
Wide Area Monitoring
21Dr.-Ing. Abdalkarim Awad
Structure
Data acquisition, carried by Phasor Measurement Units (PMU)
Data delivery through wide area communication system to PDC-Phasor Data Concentrator
Data Processing, through the system protection Center (SPC)
Command delivery
Command execution
22Dr.-Ing. Abdalkarim Awad
Dr.- Ing. Abdalkarim Awad 23
PMU1
PMU2
WAN
IEEE C37.188
PDCPhasor
Data
Concentrator
Historian
App1
…
APn
HMI
WANSubstation
Automation
System
Bay1
Bayn
Command Datae.g., DNP3
Modbus
IEC60870
e.g., DNP3
Modbus
IEC60870
LAN
PDC-Phasor Data Concentrator
HMI -Human Machine Interface
LAN -Local Area Network
PMU -Phasor Measurement Unit
Measures Voltage,
Current , phase
Architecture
24
PMU PMU PMUPMU
SuperPDC
PDCPDC
PMU
Dr.-Ing. Abdalkarim Awad
Phasor Measurement Unit (PMU)
“The phasor measurement unit (PMU) is a power system device capable of measuring the synchronized voltage and current phasor in a power system. Synchronicity among phasor measurement units (PMUs) is achieved by same-time sampling of voltage and current waveforms using a common synchronizing signal from the global positioning satellite (GPS). The ability to calculate synchronized phasors makes the PMU one of the most important measuring devices in the future of power system monitoring and control”
25Dr.-Ing. Abdalkarim Awad
Synchronized Measurements
A PMU at a substation measures voltage and current phasors:
Very precise synchronization with μs accuracy.
Compute MW/MVAR and frequency.
Measurements are reported at a rate of 20‐60 times
a second.
Can track grid dynamics in real time
Traditional SCADA refresh rate is seconds to minutes
26Dr.-Ing. Abdalkarim Awad
Phasor Data Concentrator (PDC)
Each utility has its own Phasor Data Concentrator (PDC) to:
Aggregate/align data from various PMUs based on time tag
Measurements from each utility’s PDC is sent to the Central Facility:
Where the measurements are synchronized across utilities
27Dr.-Ing. Abdalkarim Awad
OpendPDC
Complete set of applications for processing streaming time-series data in “real-time”
Measured data is gathered with GPS-time from multiple input sources, time-sorted and provided to user defined actions, dispersed to custom output destinations for archival
The openPDC implements a number of standard phasor protocols which can be used to receive data from devices.
The supported protocols:IEEE C37.118,
IEEE 1344, BPA PDCstream, FNET, SEL Fast Message,
28Dr.-Ing. Abdalkarim Awad
PMU for Wide Area Monitoring and Control
Potential PMU Applications
• Wide-Area Visualization and Monitoring;
• Angle and Frequency Monitoring;
• Inter-area Oscillation Detection & Analysis;
• Proximity to Voltage Collapse;
• State Estimation;
• Fast Frequency Regulation;
• Transmission Fault Location Estimation;
• Dynamic Model Validation.29Dr.-Ing. Abdalkarim Awad
PMU Block Diagram
Functional block diagram of the elements in a PMU.
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Phasor: reminder
A pure sinusoidal waveform can be represented by a unique complex number known as a ‘phasor’.
A sinusoidal signal
The phasor representation of this sinusoid is given by
31
)cos()( tXmtx
))sin()(cos(22
)( Xm
eXm
tx j
Dr.-Ing. Abdalkarim Awad
Phasor: reminder
Classical Definition of a PhasorThe RMS cosine-reference voltage and current phasors are.
32
i
j
v
j
IeII
VeVV
i
v
||||
||||
Dr.-Ing. Abdalkarim Awad
Convention for synchrophasorrepresentation
33Dr.-Ing. Abdalkarim Awad
Phasor
If the sinusoid is not a pure sine wave, the phasoris assumed to represent its fundamental frequency component.
The most commonly used method of calculating phasors from sampled data is that of Discrete Fourier Transform (DFT).
34Dr.-Ing. Abdalkarim Awad
Important of the Phasor Measurement
35
sin* 21
21
LX
VVP
Dr.-Ing. Abdalkarim Awad
PMU2PMU1V2
V1
Bus2Bus1XL
Compute MW & MVAR
v
jVeVV v
||||
i
jIeII i ||||
)cos( ivVIP
i
v
)sin( ivVIQ
36Dr.-Ing. Abdalkarim Awad
Synchronized Measurements
Location 1
Location 2
Phase angular difference between the two buses
can be determined if the two local clocks are
synchronized.
Synchronizing pulses obtained from GPS satellites.
37Dr.-Ing. Abdalkarim Awad
Role of GPS
Constellation of 24 satellites orbiting at 20,200 km Developed by US dept of defenseAvailable for free for civilian useBeyond navigation use, it provides time reference:
Protection systems derive usage of GPS from the timing signal
4 satellites are needed for knowing timing and location position
Satellites have atomic clocksProvides coordinated universal time (UTC) which is international atomic time compensated for leap seconds for slowing of earths rotationscan obtain accurate timing pulse every second
with an accuracy of 1 microsecond
38Dr.-Ing. Abdalkarim Awad
PMU Facts
PMU uses discrete Fourier transform (DFT) to obtain the fundamental frequency components of voltage / current(Half cycle or Full cycle)
Data samples are taken over one cycle / multiple cycles.
Resolution of the A / D converter is 16 bits.
39Dr.-Ing. Abdalkarim Awad
Example
Power Flow= 5 pu
Frequency=50
The power is estimated using bus 1 and 2 (Φ1-Φ2)
Error of time stamp at 1 is 0.1 ms and at bus2 is 0
Find the error in estimated power
40
PMU2PMU1 V2=1.0V1=1.0
Bus2Bus1j0.1
Dr.-Ing. Abdalkarim Awad
Example
0.1 ms corresponds to:
∆θ=(0.1ms/20ms)*2π
=0.0314 rad
41
52.06
5)sin(10
5)sin(21
21
21
21
X
VVP
Feq=50 Hz
Dr.-Ing. Abdalkarim Awad
Example
42
puP
X
VV
X
VVP
269.0
)sin(21
)sin(21
2121
Dr.-Ing. Abdalkarim Awad
Signals with 50 and 51 Hz
43
Blue: Cos(2*π*50*t)
Red: Cos(2*π*51*t)Dr.-Ing. Abdalkarim Awad
Table of synchrophasor values at a 10 fps reporting rate
44Dr.-Ing. Abdalkarim Awad
Fps: Frame per second
Relevant PMU Standards
C37.111-1999
A general transient data recording file format standard
C37.118.1-2005
a complete revision and dealt with issues concerning use of PMUs in electric power systems
C37.118.1-2011
Covers synchrophasor measurements for power systems
Adds frequency & rate of change of frequency (ROCOF) and dynamic operation
C37.118.2-2011
Defines real-time synchronized phasor measurement data exchange method
45Dr.-Ing. Abdalkarim Awad
C37.118.1-2005
46Dr.-Ing. Abdalkarim Awad
Example of frame transmission order
The SYNC word is transmitted first and CHECK word last.
Two- and four-byte words including integer and floating-point numbers are transmitted most significant byte first (network or “big endian” order). All frame types use this same order and format.
47Dr.-Ing. Abdalkarim Awad
Required PMU reporting rates
48Dr.-Ing. Abdalkarim Awad
Word definitions common to all frame types
49Dr.-Ing. Abdalkarim Awad
Word definitions common to all frame types
50Dr.-Ing. Abdalkarim Awad
Sync (2 bytes)
Frame synchronization word.
Leading byte: AA hex
Second byte: Frame type and Version, divided as follows:
Bit 7: Reserved for future definition
Bits 6–4:
000: Data Frame
001: Header Frame
010: Configuration Frame 1
011: Configuration Frame 2
100: Command Frame (received message)
Bits 3–0: Version number, in binary (1–15), version 1 for this initial publication.
51Dr.-Ing. Abdalkarim Awad
Word definitions common to all frame types
52Dr.-Ing. Abdalkarim Awad
Example
A PMU sent a packet that starts with following four bytes (decimal)
170,49,1,198
What is the 170?
Determine the type of frame? Data
Configuration
Command
header
What is the size of the frame?
53Dr.-Ing. Abdalkarim Awad
Example
170=0xAA (0x mean hexadecimal)
It is the SYNC byte
49=0x31=00110001b
0 (Bit 7: Reserved for future definition)
011: configuration frame 2
0001: version 1
It is a configuration frame (Config-2) and the version (1)
Then comes the two bytes size
Size=198+1*256= 454
54Dr.-Ing. Abdalkarim Awad
Configuration frame
55Dr.-Ing. Abdalkarim Awad
Configuration frame
56Dr.-Ing. Abdalkarim Awad
Word definitions unique to configuration frame
57Dr.-Ing. Abdalkarim Awad
To send a value (e.g., voltage)
It is possible to send it as a float or integer
If Integer We need to scale it
Example: to send 18.45 as 16 bit integer
Scale it e.g 1000*18.45=18450
At the receiver side: we convert it back using the same scale
18450/1000=18.45
In C37.118, PhasorMag=value*PHUNIT/100000
58Dr.-Ing. Abdalkarim Awad
FORMAT (2 Bytes)
Data format in data frames, 16-bit flag.
Bits 15–4: Unused
Bit 3: 0 = FREQ/DFREQ 16-bit integer, 1 = floating point
Bit 2: 0 = analogs 16-bit integer, 1= floating point
Bit 1: 0 = phasors 16-bit integer, 1 = floating point
Bit 0: 0 = phasor real and imaginary (rectangular), 1 = magnitude and angle (polar)
59Dr.-Ing. Abdalkarim Awad
Example
Explain the following two bytes for FORMAT field
First byte (MSB)= 0
Second byte=8
So we have 0000 0000 0000 1000
Bits 15–4: Unused
Bits 3–0:
Bit 0=0 phasor real and imaginary (rectangular)
Bit1=0 phasors 16-bit integer
Bit2=0 analogs 16-bit integer
Bit3=1 FREQ/DFREQ 32 bit float
60Dr.-Ing. Abdalkarim Awad
PHUNIT (4 bytes)
Conversion factor for phasor channels. Four bytes for each phasor.
Most significant byte: 0 = voltage; 1 = current.
Least significant bytes: An unsigned 24-bit word in 10–5 V or amperes per bit to
scale 16-bit integer data. (If transmitted data is in floating-point format, this 24-bit value should be ignored.)
61Dr.-Ing. Abdalkarim Awad
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Data frame organization
63
Data Frame
Dr.-Ing. Abdalkarim Awad
PHASORS(4/8)
16-bit integer values:
Rectangular format:Real and imaginary, real value first
16-bit signed integers, range –32 767 to +32 767
Polar format:Magnitude and angle, magnitude first
Magnitude 16-bit unsigned integer range 0 to 65 535
Angle 16-bit signed integer, in radians × 104, range –31 416 to +31 416
64Dr.-Ing. Abdalkarim Awad
PHASORS(4/8)
32-bit values in IEEE floating-point format:
Rectangular format:
— Real and imaginary, in engineering units, real value first
Polar format:
— Magnitude and angle, magnitude first and in engineering units
— Angle in radians, range –π to +π
65Dr.-Ing. Abdalkarim Awad
FREQ(2/4)
Frequency deviation from nominal, in millihertz(mHz)
Range—nominal (50 Hz or 60 Hz) –32.767 to +32.767 Hz
16-bit integer or 32-bit floating point.
16-bit integer:16-bit signed integers, range –32 767 to +32 767.
32-bit floating point: actual frequency value in IEEE floating-point format.
Dr.-Ing. Abdalkarim Awad 66
Example
If the voltage is Determine the content of the PHASORS bytes for the same FORMAT in the previous example and the PHUNIT has the following 4 bytes (0,0,47,175)
Based on the format field, we have to send the phasors as 16 bit
Byte0=00 (most significant Byte)
Byte1=00
Byte2=47
Byte3=175
PHUNIT=47*256+175=12207
67
0 2530.5
Dr.-Ing. Abdalkarim Awad
Example
Vr=2530.5
Vi=0
Before sending, we have to scale the value
ScaledVr=Vr*100000/12207=20729
This value is 16 bit
We have to send each byte
ScaledVr=20729=0x50F9
ScaledVi=0=0x0000
68Dr.-Ing. Abdalkarim Awad
Example
We have to send the real part and then the imaginary part, therefore
Fist byte=0x50=80
Second byte=0xF9=249
Third byte=0x00
Forth byte=0x00
The PDC will do
80*256+249=20729
20729*12207/100000 =2530.4
69Dr.-Ing. Abdalkarim Awad
Cyclic redundancy codes (CRC)
CRC-CCITT
g(x) = x16 + x12 + x5 +1
Dr.-Ing. Abdalkarim Awad 70
Communication options:
• Serial
• IP protocol
37.118.x message
37.118.x message
37.118.x message
37.118.x message
TCP/UDP
header
TCP/UDP
header
TCP/UDP
header
IP
header
IP
header
Transp.
header
Transp.
trailer
OPTIONS: TCP only, UDP only, TCP/UDP
71Dr.-Ing. Abdalkarim Awad
Bibliography
High Performance IEC 61850 GOOSE and Protection Relay Testing by Hachidai Ito andKenichiro Ohashi, Toshiba Corporation, Japan
IEEE C37.118 Standard
Smart Grid: Technology and Applications, 2012, ISBN 1119968682, Wiley, by Janaka Ekanayake, Kithsiri Liyanage, Jianzhong Wu, Akihiko Yokoyama, Nick Jenkins
Smart Grid : Applications, Communications, and Security by Lars T. Berger and Krzysztof Iniewski
Hamed Mohsenian-Rad, Communications & Control in Smart Grid (Slides)
72Dr.-Ing. Abdalkarim Awad