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