ABB AG Power Technologies Division Transformers
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We reserve all rights in this document and in t he information contained therein. Reproduction, use or disclosure to third parties without express authority is strictly forbidden. © ABB AG - Transforme Transformers rs 2008 2008
Phase-Shifting Transformers
Phase-Shifting Transformers
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Power Flow Control
Use of Phase-Shifting Transformers
Pay-back-Considerations
How does a Phase-Shifting Transformer work?
Examples of Technically and Commercially Driven Applications
Differences to power transformers
Phase-Shifting Transformers
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Power Flow Control with PST S
X
P=
S P= 4 p u o r G 8 0 B l u B J A -
L
V SV L X
X
V SV L X + X T
sin(φ S
Phase Shifting Transformers are Power Flow Controllers The phase angle between two systems determine the power exchange
− φ L )
V S -V L
X T
L
I V S
sin(φ S
V L
− φ L + α )
φ S - φ L + α
Power Flow Control with PST
Power-flow between two synchronous systems The “natural” phase angle difference φ S - φ L leads to uncontrolled power flow at the interfaces. To change the angle φ S or φ L may affect third party power exchange
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V S ,
G G
V L ,
S
G
L L
L
L
P PP
L P L
P P
The use of Phase-Shifting Transformers allows the independent control of power flow!
G
Power Flow Control Network Solutions
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Control power flow between networks of different utilities No influence on power flow to other networks Control load sharing between parallel lines Increase total transfer of power Transmit forced power flow down the contract path Blocks parasitic power flow from other networks
Energy Efficiency PSTs are a means to control power flows in transmission system. With control on power flows existing assets can be used more efficiently by
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Allowing higher total flow in a given corridor w/o violation of N1 criterion Optimization of total losses Allowing access of new generation (e.g. wind turbine parks)
Pay-Back-Consideration Improvement and Control of the power flow, independent of the phase angle of the system:
Increased supply of power to the customer e.g.
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100 MW for 2000 h/a will result in approximately 4 MEuro/a revenues Euro/MWh)
(at ~ 20
Pay-Back- Consideration The control of power flow is a prerequisite for marketing transmission capacity
Selling transmission capacity 100 MW may have a value of 2 MEuro/year (at ~ 20 Euro/kW-year) Pay back is possible within a period of 9 p u o r G 8 0 B l u B J A -
2 - 3 years !
Pay-Back- Consideration - Example
Italy‘s import capacity increased by ~ 1000 MW
“N-1” Criterion fulfilled at increased imports
Rapid move from stand-by to max. phase shift in case of other import lines trips
EdF
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AT
CH
Torino
Milan
SLO
Principle of Phase Shifting Transformers V1S
Transformation of V1L the injected voltage
V2S
V2L
V3S
V3L
Series transformer
Excited by the source voltage -
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Two core design
Tapped voltage of the neighboring phases, optimized intermediate Voltage Exciter transformer
Principle of Phase Shifting Transformers V
V1S
V1L
U1e
U1reg
u1in j 2 1 p u o r G 8 0 B l u B J A -
Source voltage Ue excites the Exciter transformer Tapped voltage of the neighbouring phases, optimised intermediate voltage to utilize the tap changer best
The resulting quadrature voltage uinj Will be transformed and will be injected between source and load (Voltage ∆V)
Principle of Phase Shifting Transformers The phase shifter rotates the phasor orientation between the source and load side.
VL
V 1L
V 3S
φ L V 3L
In pure phase shifting transformers a voltage in quadrature to the source voltage is injected into the line V
VS
V 1S
φ S adv
V 2S 3 1 p u o r G 8 0 B l u B J A -
V 2L
Increase of Transmission Capability 3 x 600 MVA 232/232 kV ± 35°in 59 steps Two core design 3 units delivered Aug, Sept, Oct 2006. Incl. sound enclosures + PSGuard WAM In operation since Dec 1, 2006
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Example: Two Core Design Power: 600 MVA Voltage: 232 / 232 kV Angle: +/- 35°
PST without cooling equipment during dielectric tests
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Example: PST with Sound House Power: 600 MVA Voltage: 232 / 232 kV Angle: +/- 35° -17dB sound enclosure
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Example: 1630MVA, 400kV PST in Test Field
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1630 MVA
400/ 400 kV
+18°
Losses ~ 2600 kW
Mass ~ 820000 kg
Dimensions
13.2 x 15.3 x 10.2 m
Ratings of Phase Shifting Transformers
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Typical specification:
1630 MVA through power
400 kV + 18°in certain increments
Impedances
Insulation 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 and
1630 MVA x 2 sin Φ /2 = 528 MVA for the series unit
Example: 1630MVA, 400kV in the substation
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1630 MVA
400/ 400 kV
+18°
Transportation
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Example: Loss Minimization Optimum sharing of flow on parallel 400 kV and 132 kV systems
Power: 500 MVA Voltage: 400 / 132 kV Regulation: + 22°, ± 12 % 1 active part Separate windings Losses: ~ 1200 kW Weight: 617,000 kg Tank 13.2 x 4.4 x 5.2 m V1L ∆V1
u
wr2 -vr1
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V3L
V2L
Principle of Phase Shifting Transformers Asymmetrical extended Delta design V1S
V
V1L
V3L V2S
V3S 2 2 p u o r G 8 0 B l u B J A -
V2L
Excitation of the core by the phase voltage connected in Delta A part of the resulting voltage between phase 2 and 3 Will be transformed and will be injected between source and load (Voltage ∆V)
Principle of Phase Shifting Transformers Extended Delta Design Excitation of the core by the phase voltage connected in Delta V1S
V2S
V3S
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V1L
V
V2L
V3L
A part of the resulting voltage between phase 2 and 3 will be transformed and will be injected between source and load (Voltage ∆V)
Principle of Phase Shifting Transformers
V1S
V1L
V3L
V2S
V3S 4 2 p u o r G 8 0 B l u B J A -
Single-core, symmetric design
V2L
Principle of Phase Shifting Transformers V1S ue11
V1L ue12
V2S V2L
V3S V3L
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Single-core, symmetric design
Example: Control of Loading of a Cable
450 MVA 138 / 138 kV +/- 58° extended delta design, with separate reactor 14.7 x 10.8 m 553,000 kg 6 2 p u o r G 8 0 B l u B J A -
Active Part of an Extended Delta PST Tanking of a 450 MVA, 138 / 138 kV, 58 ° active part, 247,000 kg
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Example 1 for economically driven PST project Municipal utility of Ulm, DE EnBW
~ 0 MW ~ 0 MW
UW Ost
UW West
Supply from EnBW via three 110 kV substations One line leased with very favorable conditions up to 80 MW
SWU UW Süd Dellmensingen
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0 – 80 MW
Incentive for PST: Savings in transmission fees
Example 1 for economically driven PST project 100 MVA 110/110 kV +7°in 32 steps Asymmetrical two core design ABB scope: Support of load flow study Technical proposal Support in specification of power flow controller Delivery and erection In operation since 12/07 9 2 p u o r G 8 0 B l u B J A -
Payback within about 2 years
Example 1 for Economically Driven PST Project Viertelstundenwerte vom 25.11.2005 - 1.12.2005 ¼ hour values of Nov 25, 2005 – Dec 1, 2005 90
W M n i n W e M g n i n n i e g s n i n s n e e m l m l l e l D e g n D u t s i r e l e k r i w W o P l a e R 0 3 p u o r G 8 0 B l u B J A -
80
70
Benefit With PST
60
50
40
30
20
Without PST
10
0 25-11-2005 00:00:00
26-11-2005 00:00:00
27-11-2005 00:00:00
28-11-2005 00:00:00
29-11-2005 00:00:00 Zeit
Time
30-11-2005 00:00:00
01-12-2005 00:00:00
02-12-2005 00:00:00
Example 2 for economically driven PST project
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Example 2 for Economically Driven PST Project 330 MVA 230/230 + 5% kV ± 79°in 32 steps Two core design ABB scope: Load flow studies Equipment rating study Specification of PST Delivery to site and erection of PST Substation designs Protection & Control? Line construction starting fall 2007 2 3 p u o r G 8 0 B l u B J A -
Differences to normal power transformers
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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
