electrical power distribution in experiments w.iwanski

Electrical power distribution in experiments

W.Iwanski

W.Iwanski 2

Outline

• Supplying network at CERN• Power quality• Redundancy of supply• Power availability• Monitoring and control of electrical infrastructure• Operation • Summary

25/10/2011 ESE seminar

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Powering grid at CERN


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Major power consumers at LHC

LHC Magnets

Cryogenics

CV

Experiments

Services

RF

0 5 10 15 20 25 30

15

30

20

25

15

15

Aparent power [MVA]


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Electrical supply of the LHC experiments

ALICE supply


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Electrical supply of the LHC experiments

Separation of the Machine network from the LHC General Service network in each experiment

Individual 18/0.4 kV transformers to feed separate systems

Filters on the Machine network of all LHC experiments


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• Supplying network at CERN

• Power quality• Redundancy of supply• Power availability• Monitoring and control of electrical infrastructure• Operation • Summary


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Quality of power supply at CERN(Extract from the document LHC-EM-ES-0001 rev 2.0)


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P(active)

P

P … active Power

Q(reactive)

Q

Q … reactive Power

S

S … apparent Power

S

Phasor Diagram Real Life

without SVC

What is reactive power?

Source: K.Kahle


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P(active)

P

P … active Power

Q(reactive)

Q

Q … reactive Power

S’

S … apparent Power

S

Phasor Diagram Real Life

with SVC

What is reactive power?

Source: K.Kahle

-QSVC


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F2 F3 F5TCR F7 F11 F13 HF1 HF2Pulsating

TransformerEHT2

EMD2/BE 18 kV

Load

reactive power

50% SPS

TCR

150 Mvar

filters

-130 Mvar

SPS mains

90 Mvar

Reactive power compensation

Source: K.Kahle


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Reactive power taken from EDF is almost zero!

Reactive power consumed by SPS Mains

Reactive power generated by SVC

Reactive power compensation

Source: K.Kahle


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TCR for PSB

Reactive power compensation• Up to 130 MVAr at LHC

Filtering of harmonic distortions• SPS: 20% --> 0.5%

Voltage stabilization• SPS: 14% --> 0.75%

…. But when being energized, they generate fast transient on the powering network• Turning them ON is

coordinated by the CCC with experiments

Benefits of having the Static Var Compensators


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20 30 40 50 60 70 80 90 100 110

-45%

-40%

-35%

-30%

-25%

-20%

-15%

-10%

-5%

0%

Voltage variations vs. Length of events

20102011

Temps (ms)

Varia

tion

Operating conditions

Perturbations on powering grid recorded at CERN

Source: D.Arnoult


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Power Quality Monitor

PQM monitors state of the filters in the experiment’s zone as well as on the LHC loop

It spies on alarms from the analyzers recording events happening on the 18 kV Machine and GS LHC loop networks

PQM is ready to monitor signals from local analyzers to be connected to register events on selected 400 V branches

Acknowledgeable alarms are launched on the Alarm screen in the Control Room whenever supervised equipment changes its state

Applications developed for the moment for Atlas and Alice experiments.

ALICE Power Quality Monitor synoptic view

ATLAS Power Quality Monitor synoptic view


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• Supplying network at CERN• Power quality

• Redundancy of supply• Power availability• Monitoring and control of electrical infrastructure• Operation • Summary


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Auto-transfer

Source: G.Cumer/F.Duval

Auto-transfer process managed by the controllers of the bus-bars BE9, SEM12 and ME9 during the Major Event of 07/2011


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Auto-transfer



Loss of supply for the GS Network


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Auto-transfer



Attempt to re-feed the GS from the Meyrin side


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Auto-transfer



Loss of Meyrin supply due to inrush current


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Auto-transfer


Meyrin side re-powered from the Swiss supplier



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Redundancy of supply: Re-powering

Re-powering is used at different levels of hierarchy to provide an alternative source of power in case of a failure or a maintenance up-stream

Typically, the re-powering is taken from the general service network


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Redundancy of supply: Doubled systems

Source: B.Saint-Sulpice

Additional transformer provides power from other network, following switchboards re-power each other

Redundant compressors are fed from different networks

Modifications of supply of the Cryogenic system in Atlas after the major event in 07/2011


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• Supplying network at CERN• Power quality• Redundancy of supply

• Power availability• Monitoring and control of electrical infrastructure• Operation • Summary


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AUG

Daisy-chain of AUG sensors in particular zone

Cut of supply in the zone at the level of 18/0.4 kV transformer

Supervision by ENEL SCADA

Generation of L3 alarms

Interface to DSS of experiments


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Types of supply

See mains perturbations ?

Switched off by AUG ?

Back up by Diesel set ?

Downtime ?

Normal EBD Yes Yes No

YesMains downtime

Normal EXD Yes Yes or No* Yes* or No

YesMains downtime

Assured EAD Yes Yes Yes

Yes30s to 90s

SafetyESD Yes No Yes

Yes30s to 90s

UPSEOD No Yes or No Yes or No

NoBattery autonomy :

10min to 2h

48 VDCECD No No Yes

NoBattery autonomy :

2h to 3h

* Cas unique EXD4/15A

Levels of availability of electrical supply


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Diesel supply

Supply of safety installations• Elevators• AUG• Anti-panic lighting• Ventilation• Back-up of 48 VDC supply• …

Back-up of UPS installations

Detector-specific installations which shall provide power in emergency cases (fed from experiment Diesel generators)• Magnet Heaters in Atlas• Chillers of the

Thermosiphon in Atlas

Diesel generator Normal supply

Safe power: Normal supply when power is ON or Diesel power during a power cut. There is always a short voltage loss before Diesel starts feeding the network


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UPS with a little autonomy

UPS and the by-pass are fed from the normal network

Double AC/DC DC/AC conversion + batteries are used for filtering perturbations on the mains.

Autonomy of UPS is not important but is long enough to be able to shut down equipment fed from the UPS in case of a power cut.


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UPS with a significant autonomy

UPS and the by-pass are fed from the normal network

During a power cut the UPS power is available as long as batteries allow (typically not longer than 2 hours)


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UPS with a Diesel back-up

EBD1/15

UPS is fed from the safe network while the by-pass from the normal network

During a power cut, safe network is fed from Diesel which practically assures unlimited UPS power availability


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Redundant UPS with a significant autonomy + Diesel back-up + power management

UPS is fed from the safety network while the by-pass fed from the normal network

Redundant UPS increases power availability and is convenient for long operation

During a power cut, safety network is fed from Diesel which practically assures unlimited UPS power availability

In case of a power cut and the Diesel failure, a PLC manages autonomy of the UPS by cutting less important users after 10 min


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• Supplying network at CERN• Power quality• Redundancy of supply• Power availability

• Monitoring and control of electrical infrastructure

• Operation • Summary


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9

Global view of electrical SCADA system

Source: S.Infante


Drawer number 2

HMIDCS

ModBus/TCP/IP

ModBus/JBus

DIRIS Drawer number 1

Concentrator Crate Acquisition Crate

ModBus/JBus

ENS

S SS

HMIDCS

RACK

Concentrator Crate

ModBus/JBus

ENS

TWIDO

Distribution chassis

ModBus/JBus

ModBus/TCP/IP

ATLAS/CMSALICE/LHCb

Supervision and control architecture in experiments

Source: S.Infante

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Basic infrastructure for controlling and monitoring

Rack’s supplying box Concentrating PLC

Expert panel

Concentrating PLC makes state of the system available to the supervising database (CCC) and user application (DCS)

Concentrating PLC communicates with the local PLCs in supplying boxes/cabinets (ATLAS/CMS) or reads state of powering drawers (ALICE/LHCb)

Local PLCs execute ON/OFF commands on powering breakers and monitor their state (opened/closed/tripped)

LHC Control Room (CCC)

Experiment’s Control Room

Powering drawers


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Rack Control applications

PLC in the supplying box above the rack allows for monitoring of local breakers in the repartition box (ATLAS/CMS)


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Rack Control applications

One supplying drawer brings power to few racks. No monitoring is possible of power distribution inside the rack (ALICE/LHCb)


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Control of supply of computers

Powering of 30-40 computers installed in one rack requires special attention:

Six AC Smart Start modules controlled via Ethernet provide staggered start-up of 12 blocks of 4 outlets (ALICE, 6 racks of that kind)

Two breakers controlled by the PLC via Ethernet feed two powering lines having NTC thermistors on each phase (ATLAS, ~100 racks of that kind


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Electricity Distribution Monitor

Simple but very reliable system, used for monitoring of the electrical infrastructure

Shows status of all electrical supplying cabinets important for experiment

System based on voltage presence sensors being read by the ELMB card interfaced to a local DCS station

Application developed by Atlas and integrated with the global monitoring environment of the experiment


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• Supplying network at CERN• Power quality• Redundancy of supply• Power availability• Monitoring and control of electrical infrastructure

• Operation • Summary


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Testing and maintenance of electrical infrastructure

In order to keep operability, regular testing of active components is required. Possibly in nominal conditions• Monthly testing of Diesel generators• Yearly testing of the Auto-transfer

Nominal conditions are not easy to achieve as experiment equipment typically is preventively switched off to avoid unnecessary losses. This does not help to tune settings of the protective circuits (see Major Event of 07/2011)

Periodic maintenance is planned typically for the LHC shut-down periods• UPS: every year

Redundancy of the UPS allows to keep the UPS supply running• Diesels: every year• Switchboards: every 5 years• Transformers: every 3 years


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Lessons learnt from the Major Events

Many UPSs ran out of batteries before the GS network came back. It can happen but it’s not comfortable situation when supervising systems fed from the GS network via UPS are not running anymore while supervised electronics fed from the Machine network is working fine.• Either to move supply of UPS from the GS network to the Machine one

or supply UPS from both networks Atlas lost big volume of Helium when long cut on the GS

network caused stoppage of the cooling, the Shield compressors and 400 V distribution for the Cryo services for long• Redundant Shield compressors to be fed from the GS and Machine

networks• Additional transformer fed from the Machine network to provide

redundant supply for 400 V distribution of the Cryo services


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Summary

Monitoring and control of the electrical infrastructure are key elements to provide efficient operation

Despite being in operation since several years, the electrical infrastructure is still evolving. Consolidation work is in progress

While the robustness of power supply assures quick recovery from crisis situations, the regular maintenance and testing guarantees long operability


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Thank you for your attention !


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Supporting slides


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Power delivered to the LHC experiments during operation

ALICE ATLAS CMS LHCb0

2

4

6

8

10

12

14

16

18

2018.2

7.7 7.6

17.6

0.11 0.170.88

0.10.52 0.42 0.5 0.4

Regular power [MW] UPS power [MW] Diesel power [MW]


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Active and reactive power consumed from the CERN network

Power converters

Cryogenics

CV

Experiments

Services

020

4060

80100

120

105

50

37

26

10

91

25

17

12

5

53

43

32

23

9

Active power [MW] Reactive power [MVAr] Apparent power [MVA]


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Parent-child architecture for DCS

PLC Concentrator

DCS

ENS

TGBT ABB

Coupler

Coupler

TWIDO PLCTWIDO PLC

RACKS

HM

I

CPU

Coupler

Coupler

Normal distribution

JBus

JBus

Normal distribution

SDX1

1 TGBT – 6 FEEDERS6 DISTR. SWITCHBOARDS – 40 FEEDERS

Source: S.Infante

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PLC Concentrator

DCS

ENS

TGBT ABB

INPU

T

OU

TPUT

RACKS

HM

I

CPU

Coupler

Coupler

Normal distribution

Parent-child architecture for DCS

UX15

INPU

T

OU

TPUT IN

PUT

OU

TPUT

Arrivée

2 TGBT 400V - 10 FEEDERS6 DISTRIBUTION SWITCHBOARDS

Source: S.Infante

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electrical power distribution in experiments w.iwanski

Documents

iwanski slide

ese seminarw

quality of power supply

sps mains reactive power

electrical power distribution

major power consumers

iwanski14 slide

electrical supply