phase shifting transformers july 2008
DESCRIPTION
HV PowerTRANSCRIPT
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Phase-Shifting Transformers
ABB AGPower Technologies Division
Transformers
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© ABB AG - Transformers 2008
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Phase-Shifting Transformers
Power Flow ControlUse of Phase-Shifting TransformersPay-back-ConsiderationsHow does a Phase-Shifting Transformer work?Examples of Technically and Commercially Driven Applications Differences to power transformers
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Power Flow Control with PST
Phase Shifting Transformers are Power Flow Controllers
The phase angle between two systems determine the power exchange
)sin( LSLS
XVVP φφ −=
XS L
VLVS
VS-VL
I
φS - φL + α)sin( αφφ +−
+= LS
T
LS
XXVVP
X XTLS
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Power Flow Control with PST
Power-flow between two synchronous systems
L
GG
L
G
VS , φS
L
LG
L
VL , φL
P
P
P
To change the angle φS or φLmay affect third party power exchange
PThe “natural” phase angle difference φS - φL leads to uncontrolled power flow at the interfaces.
PThe use of Phase-Shifting Transformers allows the independent control of power flow!
PP
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Power Flow Control
Network SolutionsControl power flow between networks of different utilitiesNo influence on power flow to other networksControl load sharing between parallel linesIncrease total transfer of powerTransmit forced power flow down the contract pathBlocks parasitic power flow from other networks
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Energy EfficiencyPSTs are a means to control power flows in transmission system.With control on power flows existing assets can be used more efficiently by
Allowing higher total flow in a given corridor w/o violation of N-1 criterionOptimization of total lossesAllowing access of new generation (e.g. wind turbine parks)
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Pay-Back-ConsiderationImprovement and Control of the power flow,
independent of the phase angle of the system:
Increased supply of power to the customer
e.g.100 MW for 2000 h/a will result in
approximately 4 MEuro/a revenues (at ~ 20 Euro/MWh)
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Pay-Back- Consideration
Pay back is possible within a period of 2 - 3 years !
The control of power flow is a pre-requisite for marketing transmission capacity
100 MW may have a value of
2 MEuro/year (at ~ 20 Euro/kW-year)
Selling transmission capacity
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Pay-Back- Consideration - ExampleItaly‘s import capacity increasedby ~ 1000 MW
“N-1” Criterion fulfilled at increased imports
Rapid move from stand-by to max. phase shiftin case of other import lines trips
Torino MilanF
EdFCH AT
SLO
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Two core design
V1S
Series transformer
Exciter transformer
V1L
V2S
V3S
V2L
V3L
Principle of Phase Shifting Transformers
Tapped voltage of the neighboring phases, optimized intermediate Voltage
Excited by the source voltage
Transformation of the injected voltage
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Principle of Phase Shifting Transformers
U1reg
U1e
V1S V1L
u1in
j
∆V
α
Source voltage Ueexcites the Exciter transformerTapped voltage of the neighbouring phases, optimised intermediate voltage to utilize the tap changer best
The resulting quadraturevoltage uinjWill be transformed and will be injected between source and load (Voltage ∆V)
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Principle of Phase Shifting TransformersThe phase shifter rotates the phasor orientation between the source and load side.
In pure phase shifting transformers a voltage in quadrature to the source voltage is injected into the line
∆V
αadv
VSVL
V1S
V2S
V3S
V3L
V1L
V2L
φL
φS
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3 x 600 MVA232/232 kV± 35° in 59 stepsTwo core design
3 units delivered Aug, Sept, Oct 2006.Incl. sound enclosures+ PSGuard WAM
In operation since Dec 1, 2006
Increase of Transmission Capability
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Example: Two Core Design
Power: 600 MVAVoltage: 232 / 232 kVAngle: +/- 35°
PST without cooling equipment during dielectric tests
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Example: PST with Sound HousePower: 600 MVAVoltage: 232 / 232 kVAngle: +/- 35°
-17dBsound enclosure
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Example: 1630MVA, 400kV PST in Test Field
1630 MVA
400/ 400 kV
+18°
Losses ~ 2600 kW
Mass ~ 820000 kg
Dimensions
13.2 x 15.3 x 10.2 m
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Typical specification:1630 MVA through power400 kV + 18° in certain incrementsImpedancesInsulation levels BIL and AC
The resulting equivalent rating or physical size is a result of the shifting power of
1630 MVA x 2 sin Φ/2 = 528 MVA for the main unit and1630 MVA x 2 sin Φ/2 = 528 MVA for the series unit
Ratings of Phase Shifting Transformers
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Example: Loss Minimization
∆V1V1L
V2L
V3L
u
wr2-vr1
α
Optimum sharing of flow on parallel 400 kV and 132 kV systemsPower: 500 MVAVoltage: 400 / 132 kVRegulation: + 22°, ± 12 %1 active partSeparate windingsLosses: ~ 1200 kWWeight: 617,000 kgTank 13.2 x 4.4 x 5.2 m
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Principle of Phase Shifting Transformers
Asymmetrical extended Delta design
Excitation of the core by the phase voltage connected in Delta
V2S
V1S V1L
V3S
V3L
V2L
α
∆V
A part of the resulting voltage between phase 2 and 3 Will be transformed and will be injected between source and load (Voltage ∆V)
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Principle of Phase Shifting Transformers
Extended Delta DesignExcitation of the core by the phase voltage connected in Delta
V1S V1L
V2S V2L
A part of the resulting voltage between phase 2 and 3 will be transformed and will be injected between source and load (Voltage ∆V)
∆V
V3S V3L
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Principle of Phase Shifting Transformers
Single-core, symmetric designV1S V1L
V3S
V3L V2S
V2L
α
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Principle of Phase Shifting TransformersV1S
ue11
ue12V1L Single-core,
symmetric designV2S
V2L
V3S
V3L
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Example: Control of Loading of a Cable
450 MVA138 / 138 kV+/- 58°extended deltadesign, with separate reactor14.7 x 10.8 m553,000 kg
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Tanking of a450 MVA,138 / 138 kV, 58 °
Active Part of an Extended Delta PST
active part,247,000 kg
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Example 1 for economically driven PST project
EnBW
SWU
UW West
UW Süd
UW Ost
0 – 80 MW
~ 0 MW
~ 0 MW
Dellmensingen
Municipal utility of Ulm, DE
Supply from EnBW via three 110 kV substations
One line leased with very favorable conditions up to 80 MW
Incentive for PST:Savings in transmission fees
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Example 1 for economically driven PST project
100 MVA110/110 kV+7° in 32 stepsAsymmetrical two core design
ABB scope:Support of load flow studyTechnical proposalSupport in specification of power flow controllerDelivery and erection
In operation since 12/07
Payback within about 2 years
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Viertelstundenwerte vom 25.11.2005 - 1.12.2005
0
10
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25-11-200500:00:00
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01-12-200500:00:00
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Zeit
Wirk
leis
tung
Del
lmen
sing
en in
MW
Without PST
With PSTBenefit
¼ hour values of Nov 25, 2005 – Dec 1, 2005
Rea
l Pow
er D
ellm
ensi
ngen
in M
W
Time
Example 1 for Economically Driven PST Project
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Example 2 for Economically Driven PST Project330 MVA230/230 + 5% kV± 79° in 32 stepsTwo core design
ABB scope:Load flow studiesEquipment rating studySpecification of PSTDelivery to site and erection of PSTSubstation designsProtection & Control?
Line construction starting fall 2007
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Differences to normal power transformers
Power for which phase shifter is dimensioned depends on maximum phase angle
Higher insulation demands
Larger, more complex tapped windings
Demanding specs on OLTCs: step voltages, switching power, reactance and capacitance of large tapped windings
Phase shift in load currents on a given core limb cause additional stray flux, forces, losses
Multitude of load cases to be checked for optimisation