D2-01_24
Prototype and Evaluation of
Communication Network for a WAMPAC
System Based on International Standards
System Engineering Research Laboratory
Central Research Institute of Electric Power Industry
Yoshizumi Serizawa
PS1: Role of ICT in Power System
CIGRE SC D2 Colloquium on Smart Grid
November 14, 2013
2013
1
Classification of WAMPAC system
Areal range
of influence
Wide
Rotor angle
stability
(Transient
stability)
Frequency
stability
(Wide area)
Rotor angle
stability
Frequency
stability
(Islanding)
Voltage stability
(Large disturbance)
Voltage stability
(Small disturbance)
Narrow
1 ms
Status data
for control
2013
10 ms
Cascades
phenomena
100 ms
Timescale
of control
Overload
1s
10 s
Sampled value
1 min.
10 min.
Rms value
Phasor
2
A configuration of existing WAMPAC system
Central Control Computer
System-wide
state information
Dedicated wide
area network
TE
TE
G
G
Legend
TT
Starter
TE
TE
TE
TT
G
2013
TT
G
G
TT
G TT
TE
Terminal Equipment
TT
Transfer
Tripping Equipment
Processed
result
(Generator to
be shed)
Shedding
command
3
Int’l standard-based WAMPAC system
CE – WAMPAC-GW
communication:
− IEC 61970 (CIM)
CE
- Measurement
- Status
WAMPAC-GW:
− IEEE C37.244
(Phasor Data
Concentrator)
PDC - PMU/IED
Communication :
− IEC61850-90-1
− IEC61850-90-5
− IEEE C37.118.2
(Synchrophasor
data transfer)
2013
-Control sequence
-Control table
- Setting
WAMPAC-GW
(CIM – IEC 61850)
- Measurement
- Status
-Control sequence
-Control table
PMU - IED Communication :
− IEC/TR 61850-90-1 (Inter-substation communication)
− IEC/TR 61850-90-5 (Synchrophasor communication)
- Setting
PMU
PMU:
− IEEE C37.118.1
− IEC 60255-118-1
(Synchrophasor
measurement)
Wide area communication:
− IEEE 802.1 series (Internetworking, provider backbone
bridge, etc.)
− Related IETF RFCs (Routing, IP multicast, etc.)
Time synchronization:
− IEEE 1588 (Precision Time Protocol)
− IEEE C37.238 (IEEE 1588 profile for power system)
Cyber security:
− IEC/TS 62351-1 to 10 (Data and communication security
for power system)
− IEC/TR 61850-90-5 (Security profile for synchrophasor
communication)
- Measurement
- Status
- Control command
IED
IED
- Control command
CT, VT
CB status
and others
CB
CT, VT,
CB status
and others
CE: Central Equipment
CIM: Common Information Model
WAMPAC-GW: WAMPAC Gateway
PMU: Phasor Measurement Unit
IED: Intelligent Electronic Device
4
Three types of WAN for WAMPAC system
CE
CE
GPS
WAMPAC-GW
IEEE1588
grand master clock
RSV, control table, etc.
Wide Area Network
GPS
To be excluded
if GPS receivers
installed in IEDs
and PMUs
WAMPAC-GW
IEEE1588
grand master clock
SV, control table, etc.
PTP messages
Wide Area Network
L3 switch/router
or MPLS router
L2 switch
IED
IED
PMU
L3 switch/router
or MPLS router
L3 switch/router
or MPLS router
L2 switch
PMU
L2 switch
PMU
PMU
RGOOSE
L3 switch/router
or MPLS router
Synchrophasor
RGOOSE
PMU
L2 switch
RSV, control table, scenarios, etc.
Synchrophasor
IED
PMU
CE
L3/MPLS-based
IEEE1588
grand master clock
RSV, control table, etc.
L2 switch
GOOSE
IED
L2-based
GPS
WAMPAC-GW
Wide Area Network
SV, control table, scenarios, etc.
PTP messages
L3 switch/router
or MPLS router
IED
L2 switch
L3 switch/router
or MPLS router
L3 switch/router
or MPLS router
L2 switch
PMU
PMU
L3 switch/router
or MPLS router
Synchrophasor
PMU
2013
L2 switch
RSV, control table, scenarios, etc.
GOOSE
IED
L2/L3 combined
5
Generic specifications of communication networks
Function
Communication port, Bandwidth, VLAN (L2-based), Time synchronization, Communication protocol,
Multicast operation for information sharing among devices, Identical bidirectional communication route
, Prioritized transmission
Performance
To meet the required response time, 3 to 5 ms among IEDs and PMUs, 1 s
between IED/PMU and WAMPAC-GW/CE
Less than a half of data sampling or transmission interval for ordinal data
Transmission delay
transmission. Less than 50 μs for time synchronization control channel, avoiding
variation
packet contention at normal communication ports.
Time synchronization Less than 50 μs for most stringent applications
error
Transmission error
Error rate less than 1×10−6
Reliability
Unavailability, Route assignment and redundancy, Redundancy of time synchronism
Cyber security
Security management, Availability, Integrity, Confidentiality, Key management, Access control, Network
protection
Transmission delay
2013
6
Restrictions of IEEE 1588 internetworking
IED with IEEE 1588
scheme (slave)
PTP messages
• Sync
• Follow_UP
• Delay_Req
• Delay_Resp
etc.
L2 switch network
with IEEE 1588 scheme
Message delivery
schemes
• Unicast/multicast
• Routing
etc.
IEEE 1588
grand master clock
L2 switch network
without IEEE 1588 scheme
L3 switch or MPLS network
without IEEE 1588 scheme
IED with IEEE 1588
scheme (slave)
IED with IEEE 1588
scheme (slave)
Combination of networks
L2 with
Ordinary L2 Ordinary L3
PTP
X
X
X
X
X
X
X
X
2013
Message delivery schemes and PTP clock modes
Unicast
Multicast
E2E-TC
P2P-TC
BC
E2E-TC
P2P-TC
−
−



−
−



−
−
−


−
−
−


BC




7
Performance evaluation of
IEEE 1588 internetworking
Ordinary L3 switch network
L3 switch
IEEE1588
grand master clock
L3 switch
L2 switch network
with IEEE 1588
L3 switch
L2 switch network
with IEEE 1588
Connection (b)
L2 switch
L2 switch
L2 switch
L2 switch
Connection (a)
IEEE1588
slave clock
L2 switch
IEEE1588
slave clock
L2 switch
IEEE1588
slave clock
L2 switch
L2 switch
L2 switch
L2 switch
IEEE1588
slave clock
Time synchronization errors
 Connection (a): Tens of nanoseconds regardless of traffic congestions
 Connection (b): 10 and 24 μs for background traffic loads of 5 and 95% at the L3 link,
respectively, and may be much larger for longer packet traffic
2013
8
Performance evaluation of IEEE 1588 with
bidirectional IP multicast and MPLS unicast
Rendezvous point
L2 switch
L3 switch
(BIDIR-PIM)
L3 switch
(BIDIR-PIM)
IEEE1588
grand master clock
L3 switch
(BIDIR-PIM)
L2 switch
IED/PMU
(IEEE1588
slave clock)
IED/PMU
(IEEE1588
slave clock)
Link failure
L2 switch
IED/PMU
(IEEE1588
slave clock)
L3 switch
(BIDIR-PIM)
L3 switch
(BIDIR-PIM)
L3 switch
(BIDIR-PIM)
L2 switch
IED/PMU
(IEEE1588
slave clock)
Time synchronization errors
 Bidirectional IP multicast: Temporary increase of errors by more than 30 μs (ordinary
errors of 1 to 2 μs) upon a sequence of link failure, switchover and recovery
 MPLS unicast: Similar to ordinary L2 switch network
2013
9
Prototype WAMPAC system
AMP
CE
Personal computer
IED/PMU
RTDS
WAMPAC-GW
IEEE1588
grand master clock
L3 switch
L2 switch
PMU
IED
PMU
IED
2013
PDC
Applications
L2 switch
L3 switch
L3 switch
L2 switch
Communication
cable
L3 switch
IED
PMU
L3 switch
L2 switch
IED
PMU
Communication
units
Communication specifications
Transmission delay between IED
≤ 10 ms
and WAMPAC-GW
Transmission delay between IEDs ≤ 10 ms
Communication rate of IED and
Twice per
PMU
electrical cycle
400 kbps per
Bandwidth
IED/PMU
Time synchronization error
< 50 μs
among IED/PMUs
10
Conclusions
 Based on the WAMPAC system architecture, the
communication network specifications in terms of function,
performance, reliability and cyber security were defined.
 The time synchronization characteristics were examined for
L2/L3 switches with or without IEEE 1588 schemes
implemented as well as multicast/unicast operations in IEDs
to show a satisfactory synchronization error of a few to tens of
microseconds.
 A prototype WAMPAC system comprising four IEDs was
established, and the operating time from fault occurrence to
tripping measured less than 50 ms together with satisfactory
communication and time synchronization performance.
2013
11
Special report
Q1-20: What are the cases considered for evaluation of the
proposed prototype of Wide Area Monitoring, Protection and
Control (WAMPAC) system based on IEEE 1588 international
standard?
A1-20: While WAMPAC systems may utilize various types of WAN
such as L2-based, L3/MPLS-based and L2/L3-combined
networks, IEEE 1588 was originally L2-based and immature for
wide area L3 networks. Therefore, the evaluations were
conducted to examine the internetworking of IEEE 1588 L2
and non-IEEE 1588 L2/MPLS/L3 networks with multicast or
unicast scheme in terms of time synchronization errors. The
results showed the internetworked system mostly fulfilled the
WAMPAC time synchronism requirement, 50 μs.
2013
12
Cases for evaluation
PTP master-slave time synchronism via
PTP-L2 + non-PTP- L3 network with unicast and E2ETC
PTP-L2 network with multicast and E2E-TC/P2PTC/BC
Non-PTP-L3/L2 network with bidirectional IP
multicast
Non-PTP MPLS network with unicast
with respect to traffic congestion with/without priority
control, packet losses, network failure/recovery, and
master clock switch over (BMC)
2013
13
Reserve slides
2013
14
Another configuration of
existing WAMPAC system
RPU (Remote Processing Unit)
CPU
(Central
Processing Unit)
Starter Unit
Communication
Network
RPU
• Microprocessor-based
• Control computer-based
(a)
(b)
Power plant
Substation
RPU
• Pre-calculation
• Post-calculation
• Disturbance detection
(a) Upstream information:
Pre/post-fault status data, starter signal (fault detection)
(b) Downstream information (command):
Generator shedding, load shedding, system separation
2013
15
Int’l standard-based WAMPAC system
Steady-state data flow
Data flow in the event of
the occurrence of a fault
CE
- Measurement
- Status
WAMPAC-GW
- Measurement
- Status
- Control sequence
- Control scenarios
- Setting
IEC 61850/CIM converter,
Phasor Data Concentrator, etc.
- Control sequence
- Control scenarios
- Setting
PMU
PMU
- Measurement
- Status
Power system
CT, VT, CB
2013
IED
IED
- Control command
CT, VT, CB
Generator excitation
control system
16