Central Research Institute of Electric Power Industry

1

D2-01_24Prototype and Evaluation of

Communication Network for a WAMPAC System Based on International Standards

System Engineering Research Laboratory

2013

PS1: Role of ICT in Power SystemCIGRE SC D2 Colloquium on Smart Grid

November 14, 2013

Yoshizumi Serizawa

2

Classification of WAMPAC system

2013

1 ms 100 ms 1 s 1 min. 10 min.

Timescale of control

Areal range of influence

Narrow

Wide

Rotor anglestability(Transientstability)

Overload

Frequency stability

(Wide area)

10 ms 10 s

Rotor anglestability

Cascadesphenomena

Sampled valuePhasor

Rms value

Voltage stability(Large disturbance)

Frequencystability(Islanding)

Voltage stability(Small disturbance)

Status datafor control

3

A configuration of existing WAMPAC system

2013

Central Control Computer

Terminal Equipment

Transfer Tripping Equipment

Processed result (Generator to be shed)

System-widestate information

Sheddingcommand

G

G GG G

TE

TT

G

TETE

TE

TE

TTTT TT

TT

TT

TE

Dedicated widearea network

Legend

Starter

4

Int’l standard-based WAMPAC system

2013

CE

PMU IED

- Measurement- Status

- Measurement- Status

- Control command

- Setting

- Control sequence- Control table

- Measurement- Status

- Control sequence- Control table- Setting

WAMPAC-GW:− IEEE C37.244

(Phasor Data Concentrator)

PMU:− IEEE C37.118.1− IEC 60255-118-1

(Synchrophasor measurement)

CE – WAMPAC-GW communication:− IEC 61970 (CIM)

PDC - PMU/IED Communication :− IEC61850-90-1− IEC61850-90-5− IEEE C37.118.2

(Synchrophasor data transfer)

PMU - IED Communication :− IEC/TR 61850-90-1 (Inter-substation communication)− IEC/TR 61850-90-5 (Synchrophasor communication)

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)

WAMPAC-GW(CIM – IEC 61850)

- Control command

IED

CE: Central EquipmentCIM: Common Information ModelWAMPAC-GW: WAMPAC GatewayPMU: Phasor Measurement UnitIED: Intelligent Electronic Device

CT, VTCB status and others

CT, VT,CB status and others

CB

5

Three types of WAN for WAMPAC system

2013

L3 switch/routeror MPLS router

Wide Area NetworkRSV, control table, etc.

Synchrophasor

GPS

L3 switch/routeror MPLS router

L3 switch/routeror MPLS router

L3 switch/routeror MPLS router

PMU

IED

CE

WAMPAC-GW

PMU

PMU IED

IEEE1588grand master clock

RSV, control table, scenarios, etc.RGOOSE

RGOOSE

To be excluded if GPS receivers installed in IEDs and PMUs

Wide Area Network

GPS

PMU

IED

CE

WAMPAC-GW

PMU

PMU IED

IEEE1588grand master clock

L2 switch

L2 switch

L2 switch

L2 switch

SV, control table, etc.

SynchrophasorSV, control table, scenarios, etc.

GOOSE

PTP messages

Wide Area Network

GPS

PMU

IED

CE

WAMPAC-GW

PMU

PMU IED

IEEE1588grand master clock

L2 switch

L2 switch

L2 switch

L2 switch

RSV, control table, etc.

Synchrophasor RSV, control table, scenarios, etc.GOOSE

PTP messages

L3 switch/routeror MPLS router

L3 switch/routeror MPLS router

L3 switch/routeror MPLS router

L3 switch/routeror MPLS router

L3/MPLS-based L2-based

L2/L3 combined

6

Generic specifications of communication networks

2013

Function

Communication port, Bandwidth, VLAN (L2-based), Time synchronization, Communication protocol, Multicast operation for information sharing among devices, Identical bidirectional communication route , Prioritized transmission

PerformanceTransmission delay To meet the required response time, 3 to 5 ms among IEDs and PMUs, 1 s

between IED/PMU and WAMPAC-GW/CE Transmission delay variation

Less than a half of data sampling or transmission interval for ordinal data transmission. Less than 50 μs for time synchronization control channel, avoiding packet contention at normal communication ports.

Time synchronization error

Less than 50 μs for most stringent applications

Transmission error Error rate less than 1×10−6

ReliabilityUnavailability, Route assignment and redundancy, Redundancy of time synchronismCyber securitySecurity management, Availability, Integrity, Confidentiality, Key management, Access control, Network protection

7

Restrictions of IEEE 1588 internetworking

2013

L2 switch network without IEEE 1588 scheme

IEEE 1588grand master

clock

L3 switch or MPLS network without IEEE 1588 scheme

IED with IEEE 1588

scheme (slave)

IED with IEEE 1588

scheme (slave)

IED with IEEE 1588

scheme (slave)

L2 switch network with IEEE 1588 scheme

PTP messages• Sync• Follow_UP• Delay_Req• Delay_Respetc.

Message delivery schemes• Unicast/multicast• Routingetc.

Combination of networks Message delivery schemes and PTP clock modesL2 with

PTP Ordinary L2 Ordinary L3 Unicast MulticastE2E-TC P2P-TC BC E2E-TC P2P-TC BC

X − − X X − − X X X − − − X X − − −

8

Performance evaluation of IEEE 1588 internetworking

2013

L2 switch

L3 switch

L3 switch L3 switch

L2 switch

L2 switch L2 switch L2 switch L2 switch L2 switch L2 switch

L2 switchL2 switch

IEEE1588grand master clock

IEEE1588slave clock

IEEE1588slave clock

IEEE1588slave clock

IEEE1588slave clock

Ordinary L3 switch network

L2 switch network with IEEE 1588

L2 switch network with IEEE 1588

Connection (a)

Connection (b)

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

9

Performance evaluation of IEEE 1588 with bidirectional IP multicast and MPLS unicast

2013

L2 switch

IEEE1588grand master clock

IED/PMU(IEEE1588slave clock)

L3 switch(BIDIR-PIM)

L3 switch(BIDIR-PIM)

L3 switch(BIDIR-PIM)

L3 switch(BIDIR-PIM)

L3 switch(BIDIR-PIM)

L3 switch(BIDIR-PIM)

L2 switch

IED/PMU(IEEE1588slave clock)

L2 switch

IED/PMU(IEEE1588slave clock)

L2 switch

IED/PMU(IEEE1588slave clock)

Rendezvous point

Link failure

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

10

Prototype WAMPAC system

2013

CE

WAMPAC-GWIEEE1588

grand master clock

L2 switchL2 switch

L2 switch L2 switch

L3 switch

IEDPMU

IEDPMU IED PMU

IED PMU

L3 switch L3 switch

L3 switch L3 switch

Personal computer

IED/PMU

PDC

Communicationunits

AMP

Applications

RTDS

Communicationcable

Communication specificationsTransmission delay between IED and WAMPAC-GW ≤ 10 ms

Transmission delay between IEDs ≤ 10 msCommunication rate of IED and PMU

Twice per electrical cycle

Bandwidth 400 kbps per IED/PMU

Time synchronization error among IED/PMUs < 50 μs

11

ConclusionsBased 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

12

Special reportQ1-20: 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

13

Cases for evaluationPTP master-slave time synchronism viaPTP-L2 + non-PTP- L3 network with unicast and E2E-

TCPTP-L2 network with multicast and

E2E-TC/P2P-TC/BCNon-PTP-L3/L2 network with bidirectional IP

multicastNon-PTP MPLS network with unicastwith respect to traffic congestion with/without priority

control, packet losses, network failure/recovery, and master clock switch over (BMC)

2013

142013

Reserve slides

15

Another configuration of existing WAMPAC system

2013

Power plant

Substation

RPU

CPU(Central Processing Unit)

(a) Upstream information: Pre/post-fault status data, starter signal (fault detection)

(b) Downstream information (command):Generator shedding, load shedding, system separation

(a)(b)

Starter Unit

RPU

RPU (Remote Processing Unit)

CommunicationNetwork

• Microprocessor-based• Control computer-based

• Pre-calculation• Post-calculation• Disturbance detection

16

Int’l standard-based WAMPAC system

2013

IEDPMU

IEC 61850/CIM converter,Phasor Data Concentrator, etc.

Power systemCT, VT, CB CT, VT, CB

Generator excitationcontrol system

- Control command

- Control sequence- Control scenarios

- Measurement- Status

- Measurement- Status

- Setting

- Measurement- Status

- Control sequence- Control scenarios- Setting

CE

WAMPAC-GW

PMU IED

Steady-state data flowData flow in the event ofthe occurrence of a fault