dietrich bonmann, abb monselice transformer days, may 5 ... · why phase-shifting transformers and...

© ABB Group May 11, 2010 | Slide 1

Optimized AC transmission solutions with phase-shifting transformers and shunt reactors

Dietrich Bonmann, ABB Monselice Transformer Days, May 5, 2010


Why phase-shifting transformers and shunt reactors? Components for efficient AC network operation

Phase-shifting transformers (PST) and shunt reactors are enablers for the increased use of renewable energy.

PSTs optimize the utilization and/or losses of existing transmission lines.

Shunt reactors control the balance of reactive power and the voltage profile in long transmission lines or in cable networks.

Variable shunt reactors respond to fluctuating loads.

Both belong to the portfolio of FACTS devices.


Why phase-shifting transformers and shunt reactors? Enabling the use of renewable power sources

Transport of large amounts of electrical power over long distances will play an important role in achieving European goals for energy efficiency and for the use of renewables.

Bulk HVDC transmission will change power flow patterns in the supplied AC grids.

Increased injection of independent, often fluctuating renewable power.

Consequential AC transmission bottlenecks need to be managed. PSTs!

Permits for new transmission corridors are difficult to obtain.

Cables are likely to play a major role.

Capacitive currents and voltage profiles need to be managed. Shunt reactors!


Power flow control with phase-shifting transformers Optimization of load sharing and transmission capacityTwo synchronous systems.

Transmision lines with different impedances e.g. overhead / cable or 400 kV / 110 kV.

P

P

PST impose an additional circulating current, thus improving the balance of power flows.The total transmission capacity increases.

L

GG

L

G

VS , φS

L

LG

L

VL , φL

Transmision angle

difference φS - φL

drives power flow with unbalanced load sharing of lines.The low impedance line is overloaded, limiting the total transmission capacity of the corridor.

P

P


Examples for changes in load flow around Germany Interconnections between countries

Wind

Wind Coal

Nuke

Unscheduled load flows in Belgium

Congestion of North – South corridor

Congestion of East – West corridor


Power flow control with phase shifting transformers Smaller scale applications

Additional infeed into urban network. New generation pattern.

New power flows in EHV network cause angle difference at infeedsto municipal networks.

Need to block parasitic power flow and overload due to transmission angle differences in feeding network(s).

Generator has contracts with two utilities.

Defined sharing of real power to different systems/ customers

φ1 > φ2 φ2

G GG

Cables dimensionedfor radial flow

G


Typical applications for PSTs

Avoid transmission line overloading in normal operation

Avoid post-contingency transmission line overloads

Increase N-1 secure capacity of transmission corridors

Control unscheduled load flows

Keep load flows on contract paths

Minimize overall losses in the network


Power flow control with phase-shifting transformers Phase shifting transformers are power flow controllers

)sin( LSLS

XVVP φφ −=

X

)sin( αφφ +−+

= LST

LS

XXVVPX XT

LS

LS

VLVS

VS -VL

I

φS - φL + α

The phase angle (equivalent to quadraturevoltage) between two systems determines the power exchange


based on a picture from SETFO

Starting with a symmetrical three-phase system with a certain load flow A PST shall be used to control the load flowThe PST takes a fraction of the two neighbor phases voltageCombines them as a difference voltageWhich is then injected into the third phase

Technology PST Principle

V1S

V3S

V2S

V3L

V1L

V2L


Example: TERNA Rondissone Increase N-1 secure transmission capacity

Customer need

Increase N-1 secure import capacity to Italy

ABB response

Support by preliminary PST designs for system study and specification

Support for protection and control engineering

Supply of 2 x 1630 MVA PSTs, protection and control for PST and bypass bays, integration of > 50 heritage bays into MMI

Customer benefits

Import capacity increased by approx. 1000 MW


Example: 1630 MVA, 400 kV / 400 kV, +18°


Example: Municipality of Ulm, Germany Force power flow onto contract path

Customer need

Maximize power supply via infeed with low transmission fee, but limit to 80 ± 0.5 MW

Suppress transfer flows through the city’s cable network

ABB response

Support with realistic PST data for system studies

Help with specification of PST and control system

Delivery of 100 MVA, 7° PST with very fine steps

Customer benefits

Transmission fees to EHV grid operator absolutely minimized

Pay-back in 18 months!

Viertelstundenwerte vom 25.11.2005 - 1.12.2005

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Example: Municipality of Ulm Pay-back in < 2 years, full exploitation of contract path

Viertelstundenwerte vom 25.11.2005 - 1.12.2005

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Zeit

Wirk

leis

tung

Del

lmen

sing

en in

MW

Without PSTWith PST

15 min values 25.11.2005 - 1.12.2005R

eal p

ower

flow

“Sou

th”i

n M

W

Time


Example: Municipality of Ulm 100 MVA, 110 kV / 110 kV, +7° in 32 steps

Two active parts

Single tank


Specifying a phase shifting transformer

Each unit is engineered to its specific purpose!

Physical size and cost depends on throughput power and angle regulation range.

Angle regulation range to be specified by load flow studies.

Angle increments, short circuit impedance to be determined from system requirements.

Protection and control of PSTs has special requirements.

It is highly recommended to contact your PST supplier early during the system specification stage!


ABB phase-shifting transformer solutions

Center of Competence for PSTs in Bad Honnef since 2000

Wide range of experience:

100 MVA …1630 MVA

110 kV …400 kV

+ 7°…. ± 79°

Single and multiple active part designs

87 units total, 24 delivered + 7 in pipeline from Bad Honnef, 2 in pipeline in Cordoba.

Additional support can be offered for:

System studies: load flow, short circuit, insulation coordination

Preparation of specifications

Protection and control


Variable Shunt Reactor (VSR)Tomas Olsson, April, 2010


Variable Shunt Reactor Main features

Flexible voltage stabilization when renewable energy sources, such as Wind Power, are connected to the grid.

Reduce losses in cables and long over-head power lines.

Statnett, Kristiansand site

Proven design solutions are taken from our way of building shunt reactors and power transformers.

By adding a regulation winding to a traditional shunt reactor, a number of advantages are achieved, e.g.:


Neutral

Phase terminal

OLT C

Proven design solutions from fixed inductance shunt reactors and power transformers

Variable shunt reactor design concept Unconventional reactor built on conventional technology

Proven gapped core reactor design.

Tap windings and on- load tap changer like in power transformers.


Variable shunt reactor (VSR) winding concept An unconventional reactor built on conventional technology


Apparent, real and reactive power

Apparent power at terminals of a line is P + QAll current carrying conductors are surrounded by an electric and a magnetic field.

Reactive power QPart of the apparent power is needed to build up the magnetic field around the conductor. The energy stored in the magnetic field just flows back and forth in each cycle.

The conductors also act as capacitances. Part of the apparent power is needed to charge this capacitance. The energy stored in the electric field just flows back and forth in each cycle.

Real power PAt the receiving end of the line one is mainly interested in current in phase with the voltage, for actually performing work.

Reactive power consumption

Reactive power generation


Main Applications for Shunt Reactors Voltage stabilization during light load conditions

Cables generate more reactive power than overhead lines and need shunt reactors to keep the voltage stability in the grid.

A shunt reactor should be considered at every 10-12 km for a 230 kV cable or every 6-10 km for 400 kV cables.

Very long EHV overhead lines need shunt reactors during lightly loaded conditions.

0

5

10

15

20

25

30

115 230 345 500System Voltage (kV)

Mva

r/km Overhead Line

Cable


Main Applications for Shunt Reactors Stability / voltage control at light loads

Reactor restores voltage to specified value

Voltage increase fromcapacitive generation

X

X

1

U

XQ

Q

Q

QX


How we can contribute to a greener future Lower noise levels reduce disturbances in the close surrounding

75

80

85

90

95

100

1984 1989 1991 1996 1998 2000 2002

Manufacturing year

Soun

d po

wer

leve

l [dB

(A)]Measured sound

power level versus manufacturing year

Black column –

In the factory before delivery

Blue column –

On site in 2007

ABB Reactors have low sound power from the factory and that level is kept during the operational life time of the reactors. No degeneration.


Save energy, reduce amount of equipment and provide flexible voltage stabilization.

Reduced voltage jump at switching on operation.

Coarse tuning of SVC equipment for best dynamical operation.

Reduction of number of breakers. No parallel fixed reactors.

Adjusting of seasonal related loads.

Adjusting of daily dependable loads.

Can be used as a flexible spare unit.

Flexibility for new load conditions in the network. At revisions for example.

Flexibility to move reactor to other locations.


ABB variable shunt reactors References

15 variable shunt reactors delivered during 2004 -2010 to Europe, North America and Africa.

Example of regulating ranges:13-30 Mvar50-100 Mvar110-180 Mvar120-200 Mvar

The units delivered are designed for 225 to 420 kV


Summary

Market drivers

Increased investments in renewable energy sources.

Increased energy trade and grid interconnections

Increased replacement and new deployment of cables instead of over-head lines.

ABB solution

Variable shunt reactor to adjust for daily and seasonal load variations.

Shunt reactors to reduce losses in cables.

Customer benefits

Flexible voltage stabilization.

Lower grid losses.

Reliable and state of the art ABB technology

N e u t r a l

O L T C

dietrich bonmann, abb monselice transformer days, may 5 ... · why phase-shifting transformers and...

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