Phased Refurbishment of Relays and Communication Channels

1
Phased Refurbishment of Relays and Communication
Channels
Traditional panel with analogue relays and
traditional control
Modern panel with numerical multi-function relay
2
Communication Channel Options
Dedicated channel FO shared shared
channel non-switched channel switched, time
shared packet switching suitable?
R
R
DCE
DCE
WDM
WDM
M
M
DCE
DCE
R
R
R M
R M
Transportation network
R M
R M
R M
R M
3
2 Options
Analogue relay
Analogue relay
Digital channel
87L
87L
Digital relay
Digital relay
Digital channel
87L
87L
4
Remote Interrogation and Data Acquisition for DMS
R2R
R2S
Legend DCE digital communication equipment SCM
supervisory control mimic R2R relay-to-relay
coms R2S relay-to-subscriber coms

5
WEB Publishing
Enterprise subscribers
Web clients Relay engineer maintenance staff
etc.
mobile
Intra net
Substation
Router
Ethernet TCP/ IP
Bay Data publishing
Content provider Relay or bay controller with
embedded WEB server
6
Scope of Functions
7
(No Transcript)
8
Optional Communications Media
Optional communication media
Optical fibres
87L
87L
Pilot wires
Digital Coms network
ISDN
9
Quality of Supply, QoS

• Latency, slot time (not necessarily data rate)
• latency band ( min. to max.), differential
  latency, critical net load,
• Propagation time
• Propagation time differential
• dependability, Bit Error Rate BER
• BER for lt1 min, lt1 sec, non-available if BER
  gt10-3 for gt10sec
• BER under fault conditions?
• measurement within time windows lt100ms
• loss-of-channel, hot stand-by, back-up routes
• Route switching may cause nuisance alarm of relay
  monitor
• hostile environment, EMC, IEC 255
• security
• inherent measures, e. g. permissive signals
• protocol security

10
Induced Voltage along a Pilot Wire Pair
I fault current
barrier transformer
V
V2
V
V1
Legend I earth fault current 0 flux generated by
E/F - current V induced voltage
E 2?f M I L r1 r2

11
Induced Voltage, Calculation Example
Legend f frequency f 50 Hz M induction between
power and pilot cable per km, for a distance of
80 cm between cable and pilot wires, and for an
earth conductivity of 0.02 s/m e.g. M 1.347
mH/km I earth-fault current e.g. I 15
kA L length of parallel running cables e.g. l
8.4 km r1 reduction factor of h.v. cable r1
0.2 - 0.4 for single conductor oil
cables e.g. r1 0.3 r1 0.1 for cables in
steel pipes r2 reduction factor of pilot
cable r2 1 for unscreened cables r2 0.4
for best screening e.g. r2 0.4
12
Galvanic Separation of Pilot Wire and Relay
Potential
relay panel
pilot cable sealing end
barrier transformer prevents 'dirty potential' to
enter the relay panel
20 kV
500 V
'clean potential'
'dirty potential'