Phase Shifter Transformer, from design ot operation - · PDF filePhase Shifter Transformer, from design to operation IEEE Power Engineering Society, Event of 21. February at BKW David

Phase Shifter Transformer,from design to operation

IEEE Power Engineering Society,

Event of 21. February at BKW

David Orzan

BKW/Titel/Kurzzeichen/Seite 2

Agenda

1. Problematic: Large transit in the transmission network

2. Specification: Load flow calculation and network contraints/requirements

3. Engineering and technology: The features to care about andthe details that matter

4. Operation: Experience and perspectives


Transmission network in the region of Bassecourt

400 kV220 kV


Substation of Bassecourt


Failure of a 220 kV bushing in Bassecourt, Winter 2001

2*400 MVA


Failure in the tap winding of theparallel transformer

2*400 MVA


Learnings of Winter 2001Additional transformer capacity is needed in Bassecourt (Repair

may last months)

Power flow must be controlled more effectively (Diagonal control is not sufficient)

Critical transformer components must be monitored

Bushings must be specified with additional reserve (voltage andcurrent ratings)

Overvoltage protection of old transformers must be improved(modern surge arresters needed)


Basic modelIllustration of the advantage of the phase shifter with 2 scenarios:

• Increase in transmitted power on the transmission system

• Contingency in the regional system


Advantages of the phase shifterAbility to control power flows and thus...

Increase operation flexibility

Increase network security

Increase in transmission capacity

Reduction of the losses in the regional network

Reduction of the network costs when the transformer infeedsare subject to different tarifs for the transmission network usage


Network studies• Operation requirements

• Scenarios

• Results

• Objective: define the rated power, voltage ratio, voltage step


Operation requirements• Active power control

– Summer : between -100 MW and 100 MW– Winter : between 100 MW and 365 MW

• Voltage control– 380 kV : between 395 kV and 420 kV– 220 kV : between 223 kV and 245 kV– 132 kV : between 136 kV and 145 kV– 50 kV : between 47 kV and 51 kV

• Independent voltage and active power control• Maximum active power step: 20 MW per tap change• Ability to operate the main transformer (shunt unit) without the

quadrature regulating transformer (series unit)• Parallel operation with the other transformers for a short duration• Overload capability, Linear voltage control


Parameter 1: Design variantesAmong all proposed designs 4 variantes have been studied extensively:

Var. 1.1: HT 400/141.6 kV (+/- 12 Stufen ; 1.2 kV/Stufe)RT +/- 17 Stufen ; 2.17 kV/Stufe

Var. 1.2 HT 400/141.6 kV (+/- 12 Stufen ; 1.2 kV/Stufe)RT +/- 17 Stufen ; 1.75 kV/Stufe




Parameter 2: Network loadingParameter 3: Network configuration• Network loading: Winter/Summer, Today/Future, Day/Night, ...

• Many network configurations have been simulated by disconnecting parallel path (Transmission lines or transformerson the North-South axis, close to the substation of Bassecourt)


Extensive load flow calculations

Transformer design

Var 1.1

Var 1.2

Var 2.1

Var 2.2

Network load

Winter todayWinter futureSummer todaySummer future...

Network configuration

Elt. 1 outElt. 2 out...Elt. n Out


OutputFunction(Transformer design ; Network load ; Network configuration)

Output:• Loading of the network elements• Voltage in the region of Bassecourt• Controlability of the PST: The ability of the transformer to control

the 132 kV voltage and the active power transmitted independantly


Control of voltage and active powerVariante 1.2 (400/141.6 , 1.75 kV) ; Summer today ; All elt. connected

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

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10111213141516171819202122232425

21

23 24 25 26 27 28 29 30 31 32 33 34 35

Possible working pointVoltage limit in the 132-kV-network

U1 > 145 kV

Voltage vector


Active power control depends on the network loading

Power flow in the transformer 400/132 kV (Variante 1.2)

-300

-200

-100

0

100

200

300

400

500

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

Step of the series unit

P (M

W)

Summer todayWinter todayWinter future

Positive means flow from the transmission to the regional network

Last slide


Comparision with different transformer designsSummer today, comparision of different transformer design

Big influence on the controlability1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

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21

23 24 25 26 27 28 29 30 31 32 33 34 35

Var. 1.2400/141.6 kV1.75 kV

Var. 2.1400/151.6 kV2.17 kV

Var. 2.2400/151.6 kV1.75 kV


Control of voltage and active powerVariante 1.2 (400/141.6 , 1.75 kV) ; Winter today

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

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21

23 24 25 26 27 28 29 30 31 32 33 34 35

Possible working point

Limit of the voltage in the 132 kV network

Limit of the transformer (MVA)

U1 < 136 kV

U1 > 145 kV


Active power control depends on the network loading

Power flow in the transformer 400/132 kV (Variante 1.2)

-300

-200

-100

0

100

200

300

400

500

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

Step of the series unit

P (M

W)


Positive means flow from the transmission to the regional network

Last slide


Comparision with different transformer designsWinter today, comparision of different transformer design

Big influence on the controlability

Var. 1.2400/141.6 kV1.75 kV

Var. 2.1400/151.6 kV2.17 kV

Var. 2.2400/151.6 kV1.75 kV


Active power control with different PST designs

Active power through the transformer (Summer today)

-400

-300

-200

-100

0

100

200

300

400

500

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

Tap position of the series unit

P (M

W)

Var. 1.1Var. 1.2Var. 2.1Var. 2.2


Active power steps in differentnetwork loading conditions

Active power step per tap change (Variante 1.2)

0

5

10

15

20

25

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35


ΔP

(MW

)



Active power steps with different PSTdesigns

0

5

10

15

20

25

30

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

Δ P (M

W)

Var. 1.2Var. 2.1Var. 2.2Var. 1.1

Active power step per tap change (Summer today)



Diagonal controling PST

Summer today Winter today Winter future

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21

23 24 25 26 27 28 29 30 31 32 33 34 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

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10111213141516171819202122232425

21

23 24 25 26 27 28 29 30 31 32 33 34 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

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21

23 24 25 26 27 28 29 30 31 32 33 34 35

• Working point on a line (Voltage and active power closely linked)• Results in unwanted reactive power flows• A diagonal regulation would have been too restrictive and

could not have fullfiled the operation requirements


Engineering and project ManagementexperienceSpecifications and construction

Quality control and test

Transport

Project in an existing substation


Shunt and series units

400 kV

132 kV

Compensation Transformer(Utertiary=cst)

Tertiary windings

Aut

otra

nsfo

rmer


Data sheetShunt unit400 MVA, auto transformerYNa0d11400/140 kV ± 9x1,68 kV / 49 kV425 tonnes (240 t without oil)L x B x H: 14,17 x 8,34 x 10,21 m

Series unit66.4 MVAIII y n49 kV and 12 x 1,75 kV165 tonnes (55 t without oil)L x B x H: 12,4 x 6,15 x 8,24 m


Schedule plan

1. Q 2. Q 3.Q 4.Q 1.Q 2.Q 3.Q 4.Q 1.Q 2.Q 3.Q 4.Q

KonzeptSpezifikationEvaluationAnlagenerweiterungTrafobestellung, Dez.03Konstruktion1. Design-ReviewFabrikation / PrüfungRedesignFabrikation / PrüfungAbschluss WerkprüfungTransport/MontageInbetriebsetzungKommerzieller Betrieb

2003 2004 2005


Acceptance tests in the factory


Challenging transport (240 t for the shunt unit)


Challenging transport


Extensive acceptance tests on site


Extensive acceptance tests on site


Technical features and specialitiesCompensation transformer

Protection systems

Monitoring systems


Why a compensation transformer?U(TapShunt; TapSeries)

1 3 5 7 9

11 13 15 17 19 211

6

11

16

21

100

110

120

130

140

150

160

170

Voltage [kV]

Series unit

Shunt unit

160-170150-160140-150130-140120-130110-120100-110


Why a compensation transformer?φ(TapShunt; TapSeries)

1 3 5 7 9 11 13 15 17 19 211

5

913

1721

25

-5

0

5

10

15

20Phase (°)

15-20

10-15

5-10

0-5

-5-0

Series unit

Shunt unit


ProtectionThe protection system of normal transformers are well known

A phase shifter transfomer needs additional protection schemes– Strategic unit– Presence of a series winding– Ability to operate the main transformer (shunt unit) without

the quadrature regulating transformer (series unit)– Presence of a bus bars connecting the tertiary of the main to

the series winding


Overview of the protection schemes

Distanz-schutz

Differential-schutz

Hochimpedanz-schutz


Point on the wave switching

[pu]

0 4 8 12 16 20

0.0

0.3

0.6

0.9

1.2

1.5

[ms]

dT

Voltage between the circuit breaker contacts

Dielectric strength of the inter contact spac


Why point on the wave swichtingTo reduce the electromechanical forces when energizing the

transformer (Inrush current)

0 4 8 12 16 200

200

400

600

800

1000[A]

[s]

0.00 0.02 0.04 0.06 0.08 0.100

200

400

600

800

1000

10.00 10.02 10.04 10.06 10.08 10.100

3

6

9

12

15

19.90 19.92 19.94 19.96 19.98 20.00-3

-2

-1

0

1

2

3


On Line MonitoringDissolved gas in oil monitoring

Bushing monitoring

Tap changer monitoring

Not for protection function: Alarm, i.e on tripRecording and archiving of the data for trend analysis and decision

making (condition based maintenance)Communication also possible via mobile phone (Expert)On line monitoring and off line periodic measurement (DGA, Frau,

SDS) complet each other


Disolved Gaz in oil on line monitoring

(H2, CO)


Bushing on line monitoring

GelernteVektor

Fault identificationHomopolar current

Fehler-Fall


Tap changer on line monitoringMonitored parameters: Torque, Temperature, Contact erosion, Number

of switching operation


Operation experienceThe transformer can be operated as expected by the simulations

(Voltage and active power control)

Parallel operation is possible under specific conditions and for ashort duration (some minutes)

Stable protection: Some short circuit on transmission lines close tothe substation have not resulted in a false trip of the transformer

Control and monitoring systems work as expected


Example of the control capability

Typischer Lastverlauf

7

9

11

13

15

17

19

0 25 50 75 100

Stuf

enst

ellu

ngen

-100-50050100150200250300350

Q [M

Var]

P

[MW

]

Quer LängsP [MW] Q [MVar]P ohne Regelung [MW]

Nacht Tag Nacht Tag


Perspective and improvementsControl the active power more actively for example to reduce

losses in the regional network.

Dynamic transformer loadability


On line transformer loadability monitoring

Documents

Phase Shifter Transformer, from design ot operation - · PDF filePhase Shifter Transformer, from design to operation IEEE Power Engineering Society, Event of 21. February at BKW David