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GRID
Smart solutions for GIS
François Gallon
GIS PL Technical Dir. (France)
Central Board of Irrigation and Power
Delhi, India – 21 April, 2011
Smart grid
-
380kV
110kV 25kV220/110kV
20kV20kV
400/230V
380/220kV
12kV 380kV
Power flow
Heavy Industry
Residential Areas
Residential Farmhouses
Transmission Network
Rail Traffic
Department Stores, Offices, Light Industry
Power plant
Farmhouses
Transmission Network
Rail Traffic
Dramatic changes of the Power SectorFrom a one-way centralized structure Generation -> Consumption..
« The Smart Grid transforms the current Grid to one that functions more cooperatively, responsively andorganically »
Smart grid
Wind Farms
Central power plantFuel Cells
Industrial Plants CHP
Residential
Department StoresMicro-turbines
StorageVirtual Power Plant
Power flows
… to a multi-directional flow of energy and information
• Drivers
Grid security: prevention of major failures inception
Capacity
Stability
Reliability
Life extension of the existing assets
Quality of Service: control of temporary/transient phenomena
o Supported by the application of the IEC61850 : Implementation of a ‚real-time‛ systems of communication within the substation Integration of all measure & protection, control, and monitoring functions within the substation
Smart grid
The GIS Substation is one of the major components of the value chain of a Smart Grid
Condition monitoring
A Condition Monitoring system enables
• Assessment of the actual operative conditions of equipment
• Maintenance scheduling,
• Earlier identification of potential failure inception
• Support decision of activities (maintenance, operation, engineering and, eventually for asset management)
Type of Condition Monitoring
• Off-line monitoring (-> time-based inspections)
• On-line monitoring (continuous)
• Expert monitoring (data crunching & analysis, support to diagnostic)
Scope of the Condition Monitoring
ToolProductSystem
SF6 PD CB
Expert Level− RPH Manager− PD Manager− BW Manager
Substation Level− GIS Watch
Bay Level− BWatch3 ‘Gas density and CB’− PDWatch ‘Partial discharge’− RPH controller ‘controlled switching’
CONTROLBAY LEVEL
Ma
inte
na
nc
eO
pe
rati
on
Ex
pe
rtis
e
Scaleable monitoring solution for various needs
SUBSTATION LEVELSUPERVISE
LocalRemote
Expert SWMANAGE
EXPERT LEVEL
TRAINING
Agenda
Circuit-breaker condition monitoring
SF6 monitoring
Partial Discharge monitoring
Evolution of the monitoring in GIS
Densityswitch
P T
L1
L2
L3
Pressure measurement compensatedby temperature (equivalent P at 20°C)
3 alarms On/Off : L1, L2, L3
LVCC
Relaying
Logical datagathering
Conventional gas control
N cablesx 6 wires
Alarms andinterlocks
Usually the monitoring in GIS consisted in :− Conventional SF6 gas control using density switches − Gas alarms only carried over the LVCC mimic
Main drawbacks : − No indication in case of any sensor problem− SF6 leakage in the atmosphere without indication before stage 1
Evolution of the monitoring in GIS
In the 2000’s, the GIS monitoring integrated the last technologies − Digital sensors and PLC
Ex.: Bwatch3 Gas monitoring
Pressure & temperature
sensor
P
T
1 cable
x 4 wires
Temperature measurement
Pressure measurement
Acquisition
& Process
Unit CPU
Monitoring software
- Thresholds management
- Anticipated alarms
- Leakage calculation
- Sensor's monitoring
- Alarms gathering
- Density & liquefaction
calculation
LVCC
Sensor's
monitoring
Alarms &
interlocks
GIS monitoring system: BWatch3
• BWatch3 is an on-line fully digital GIS monitoring sytem
• Main functions are
− Dielectric gas density monitoring
− Gas leakage detection
− Enclosure internal fault localisation
− Circuit-breaker condition monitoring
− Self-diagnosis of the complete system
T155-CB
Filling pressure
8.5 bar abs @ 20°C
Density
56.95 g/l
Liquefaction
-25°C
SF6 characteristics
Monitoring bus layout
Acquisition & Process unit
Sensor bus
A sensor for each compartment
Low Voltage Control Cubicle
RS232
link
Acquisition &
Process Unit
Bay computer
RS485
link
GIS AREA
Monitoring
gateway
CMU
To next GIS
bays
Fiber
optics
LAN
Monitoring LAN
HV equipments
RS485 Modbus 115 Kbd
CB
CT4-20 mA
IEC 61850-8-1
Station control
equipmentLevel 2
alarms
GIS Monitoring Advanced Communication
Ethernet TCP/IP
e-terracontrol
SF6 monitoring : real-time data
SF6 monitoring : density trends
Some pictures
Designed to operate under the most adverse env. conditions
Agenda
Circuit-breaker condition monitoring
SF6 monitoring
Partial Discharge monitoring
Circuit-breaker pole
LCC
Circuit Breaker Drive Cabinet
Auxiliary Contacts
CSa
CSb
BK CPU GM DI16 AI4 AI4
Operating Coils
Closing
Tripping
Y1
Y2Y3
CMU
MonitoringGateway
IWatchCoilWatch
To next bay
GLOSSARYAI4 : 4 Analog InputsBK : Remote Bus ModuleCMU : Central Monitoring UnitCoilWatch : Operation Order Detection ModuleCT : Current TransformerDI16 : 16 Digital InputsGM : Gas MonitoringIWatch : Current measurement moduleLCC : Local Control Cabinet
Optic Fiber LAN
Ethernet
TCP/IP
CT
Interface Relays
BWatch3
Travel Sensor
Circuit-breaker monitoring layout
Circuit-breaker monitoring HMI
CB operation
archives
CB travel curves
Electrical wear
Online BWatch3 monitoring benefits
• Asset management tool
− Equipment continuous condition monitoring− Maintenance strategy (time based to preventive)− Lifetime coordination lifetime extension
• SOE (sequence of events) features
− Archive of the events recorded during GIS equipment lifetime− Advanced communication feature to SCADA
• SF6 management tool
− Enable optimization of spare gas quantities
Agenda
Circuit-breaker condition monitoring
SF6 monitoring
Partial Discharge monitoring
(1) CIGRE Brochure 150
Context
• GIS are proven to be very reliable but high costs are involved in case of failure
• The majority of incidents encountered on GIS is of dielectric origin. The incipient defects are a source of PD activity before a flashover occurred in the compartment :− For voltage class > 300 kV, more than 50% of failures is breakdown of insulation (1)
− Of these failures, 90% occurred during normal AC service conditions
These dielectric defects may lead to a flashover
Partial discharges sources must be detected at an early stage:− Preventive dielectric diagnostic possible− Mitigation of the risk of flash-over occurrence− Reduce expenditure of maintenance and refurbishment
Nota : flashovers occurring during commissioning are not abnormal events
U~
E 0
U~
E 0
U~
E 0
U~
E 0Dissociated gas
Disintegrated particle
Partial discharge issue
Partial Discharge Monitoring – Principle of UHF method
Defaul
t
Principle of PD detection using the UHF method :
• Partial discharges generate electromagnetic waves in the UHF range (200 MHz - 1500 MHz) guided along GIS enclosures
• The signal is tapped through antennas located within the GIS enclosure
• Predictive maintenance under live operation of the GIS is possible
Partial Discharge Detection : Alstom PDWatch
Acquisition Unit: UHF100 module
− 6 PD Couplers− Frequency scan (300–1200MHz)− Synchronisation by VT (inductive) or coupler
(capacitive)− Phase resolved analysis− Ethernet 100 MHz− Integration inside LVCC or stand-alone box
(GIB / GIL)
OK Defect or external disturbance ?
Partial Discharge Monitoring - Introduction
Normal conditions Defect conditions
PD threshold level
• Usual UHF method: alarm triggered by a threshold on analog UHF signal (Phase resolved analysis)
Risk of spurious alarms
UHF General Environment
External UHF signals : Light, radar, bushing, transformer, motor
GIS UHF signals
Exemple of partial discharge coupled to external noise
External environment around a GIS
Corona effect»Light noise
»Cell phone noise
»Corona noise
Examples
Normal conditions
-100
-90
-80
-70
-60
300 500 700 900 1100
Defect conditions
-100
-90
-80
-70
-60
300 500 700 900 1100
PDwatch – Online monitoring algorithm
Innovative approach: spectrum analysis (frequency scan) with band exclusion pre-processing
• External noise gating through ambiant sensor• Specific masks applied for rejecting external disturbances
Typical layout on a GIS bay
UHF links
Synchronisation links
Ethernet links
HMI PC
Ethernet switches
UHF modules
Central Unit
Bay cubicles
UHF couplersVoltage
transformers
Toward other modules
MODEM
Remote PC
Internet
Expert supprt group in GIS PL
PDWatch – Online monitoring - Human Machine Interface
− A single line diagram of the substation with the position of sensors
The software of the PDwatch includes
Practical :
PD couplers are shown on mimic diagram together with gas compartments
Partial discharge analysis methodology
1 - PD ACQUISITION
2 - PD EXPERTISE
Partial discharge signal classification
Expertise: classification in 5 main types
• Protrusion electrode− LV protrusion (enclosure)− HV protrusion (conductor)
• Floating electrode
• Defective insulator
• Free moving particle
• Noise signal
Protrusion electrode – Typical pattern
PROTRUSION ELECTRODE (HV TYPE)
PROTRUSION ELECTRODE (LV TYPE)
Insulator defect – Typical pattern
SPACER VOID
INSULATING ROD DELAMINATION
Free moving particle – Typical pattern
BOUNCING PARTICLE
Conclusion
• The system can be applied on either new GIS or retrofit project
• PDWatch is the first system in the market capable to discriminate through innovative techniques between real partial discharges & external noises
• User-friendly interfaces enable maintenance staff to − Assess severity of the partial discharge activity− & provide relevant guidance for operation
• Training sessions and manufacturer accreditations available for superior expertise
Line switching considerations
Network constraints
• For very high voltage networks, (above 362kV), insulation levels are determined by switching overvoltages generated during closing and more critically reclosing of overhead lines
• Minimizing these overvoltages has a direct impact on network security & availability
SystemTransmission line
• HV switching corresponds to a sudden change of systems conditions, giving rise to different kinds of transient phenomena− Travelling waves (reflections on long transmission lines) − Significant overvoltages (up to 4 p.u.)− Strong inrush currents
Line switching considerations
Remote end(Receiving end)
Sending end
Shunt-reactor compensated transmission line
»High degree of compensation »Low degree of compensation
Post-fault clearing sequence example− Typical waveforms of voltage across Circuit-breaker (healthy phase)
− Reclosing sequence with maximum overvoltage produced when CB closed at beat maximum across circuit-breaker
-2
-1
0
1
2
0 100 200 300 400Time [ms]
Volta
ge [p.u
.]
Time [ms]
-2
-1
0
1
2
0 50 100 150 200 250
Vo
lta
ge
[p
.u.]
Voltage across circuit-breaker
Source side voltage
Line side voltage
Closing input(random) Target for closing
Sliding window for data analysis Re-built window
tCB Predicted tdRPH
tCBtdRPH
Real time
Closing output
Controlled switching principle
tCBCircuit-breaker operating time
tdRPHTime delay introduced by point on wave controller
Voltage across circuit-breaker
Source side voltage
Line side voltage
Switching overvoltages mitigation means
Existing techniques to mitigate effects of SOV
• Staggered closing of the poles
• Pre-insertion resistors
• Modern metal-oxide surge arresters− At line terminals, at some intermediate points
• Point on the wave controller− For closing/auto re-closing of compensated long OHL (RPH3)
• And/or combination of above means
Statistical voltage profile along a long transmission circuit
Line switching systems overvoltage profile
(1) CIGRE WG C4.306
Example: 285km 500kV/60Hz shunt-reactor compensatd line
Field experience with BC Hydro HV system
+
Circuit-breaker refurbishment project
Reclosing
-6
-5
-4
-3
-2
-1
0
1
2
3
1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.30 1.31 1.32 1.33 1.34 1.35 1.36 1.37 1.38 1.39 1.40
Time (sec)
Dif
fere
nti
al
vo
lta
ge
(p
.u.)
-3
-2
-1
0
1
2
3
4
5
6
CB
cu
rre
nt
(se
co
nd
ary
va
lue
A)
ULa-Usa Open_A Close_ABC Target_A Cout_A Restart_IA Ia
Td Tcb
Tc
Field test results : high degree of compensation
• Single pole tripping and fast reclosing sequence
Reclosing
-6
-5
-4
-3
-2
-1
0
1
2
3
1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.30 1.31 1.32 1.33 1.34 1.35 1.36 1.37 1.38 1.39 1.40
Time (sec)
Dif
fere
nti
al vo
ltag
e (
p.u
.)
-3
-2
-1
0
1
2
3
4
5
6
CB
cu
rren
t (s
eco
nd
ary
valu
e A
)
ULa-Usa Open_A Close_ABC Target_A Cout_A Restart_IA Ia
Field test results : low degree of compensation
• Single pole tripping and fast reclosing sequence
Td Tcb
Tc
Conclusion
• Advanced solution for optimum switching operations & overvoltages reduction
• Power system security
• Flexibility to any network condition whatever the actual level of compensation
• Training sessions and manufacturer accreditations available for superior expertise