Dietrich Bonmann, ABB Monselice Transformer Days, May 5, 2010 Optimized AC transmission solutions with phase-shifting transformers and shunt reactors

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1 Dietrich Bonmann, ABB Monselice Transformer Days, May 5, 2010 Optimized AC transmission solutions with phase-shifting transformers and shunt reactors May 11, 2010 Slide 1

2 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. May 11, 2010 Slide 2

3 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! May 11, 2010 Slide 3

4 Power flow control with phase-shifting transformers Optimization of load sharing and transmission capacity Two synchronous systems. Transmision lines with different impedances e.g. overhead / cable or 400 kv / 110 kv. Transmision angle difference φ S - φ L drives power flow with unbalanced load sharing of lines. The low impedance line is overloaded, limiting the total transmission capacity of the corridor. PST impose an additional circulating current, thus improving the balance of power flows. The total transmission capacity increases. V S, φ S G G G L L P P V L, φ L L L L G May 11, 2010 Slide 4

5 Examples for changes in load flow around Germany Interconnections between countries Congestion of North South corridor Wind Unscheduled load flows in Belgium Wind Coal Congestion of East West corridor Nuke May 11, 2010 Slide 5

6 Power flow control with phase shifting transformers Smaller scale applications Additional infeed into urban network. New generation pattern. G G φ 1 > φ 2 φ 2 G New power flows in EHV network cause angle difference at infeeds to municipal networks. Cables dimensioned for radial flow Need to block parasitic power flow and overload due to transmission angle differences in feeding network(s). G Generator has contracts with two utilities. Defined sharing of real power to different systems/ customers May 11, 2010 Slide 6

7 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 May 11, 2010 Slide 7

8 Power flow control with phase-shifting transformers Phase shifting transformers are power flow controllers S X L P = V V S X L sin( φ φl) S V S V S -V L I V L φ S - φ L + α The phase angle (equivalent to quadrature voltage) between two systems determines the power exchange S X X T L P VSV L X + X = S L T sin( φ φ + α) May 11, 2010 Slide 9

9 Technology PST Principle V 1S V 1L V 2S V 2L V 3S V 3L Starting with a symmetrical three-phase system with a certain load flow A PST shall be used to control the load flow The PST takes a fraction of the two neighbor phases voltage Combines them as a difference voltage Which is then injected into the third phase May 11, 2010 Slide 10 based on a picture from SETFO

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

10 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 MW May 11, 2010 Slide 11

11 Example: 1630 MVA, 400 kv / 400 kv, +18 May 11, 2010 Slide 12

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.

12 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 Viertelstundenwerte vom Customer benefits :00: :00: :00: :00:00 00:00:00 Zeit :00: :00: :00:0 Transmission fees to EHV grid operator absolutely minimized Pay-back in 18 months! May 11, 2010 Slide 13

13 Example: Municipality of Ulm Pay-back in < 2 years, full exploitation of contract path 15 min values Viertelstundenwerte vom Real Wirkleistung power flow Dellmensingen South in MW in MW Without PST With PST :00: :00: :00: :00:00 Zeit Time :00: :00: :00: :00:00 May 11, 2010 Slide 14

14 Example: Municipality of Ulm 100 MVA, 110 kv / 110 kv, +7 in 32 steps Two active parts Single tank May 11, 2010 Slide 15

15 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! May 11, 2010 Slide 16

16 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 May 11, 2010 Slide 17

17 Tomas Olsson, April, 2010 Variable Shunt Reactor (VSR) May 11, 2010 Slide 18

Variable Shunt Reactor Main features By adding a regulation winding to a traditional shunt reactor, a number of advantages are achieved, e.g.: Statnett, Kristiansand site Flexible voltage stabilization when renewable energy sources, such as Wind Power, are connected to the grid.

18 Variable Shunt Reactor Main features By adding a regulation winding to a traditional shunt reactor, a number of advantages are achieved, e.g.: Statnett, Kristiansand site 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. Proven design solutions are taken from our way of building shunt reactors and power transformers. May 11, 2010 Slide 19

19 Variable shunt reactor design concept Unconventional reactor built on conventional technology Proven gapped core reactor design. Tap windings and onload tap changer like in power transformers. Neutral Phase terminal OLT C Proven design solutions from fixed inductance shunt reactors and power transformers May 11, 2010 Slide 20

20 Variable shunt reactor (VSR) winding concept An unconventional reactor built on conventional technology May 11, 2010 Slide 21

Apparent, real and reactive power Reactive power consumption Reactive power generation Apparent power at terminals of a line is P + Q All current carrying conductors are surrounded by an electric and

21 Apparent, real and reactive power Reactive power consumption Reactive power generation Apparent power at terminals of a line is P + Q All current carrying conductors are surrounded by an electric and a magnetic field. Reactive power Q Part 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 P At the receiving end of the line one is mainly interested in current in phase with the voltage, for actually performing work. May 11, 2010 Slide 22

22 Main Applications for Shunt Reactors Voltage stabilization during light load conditions Mvar/km System Voltage (kv) Overhead Line Cable 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 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. May 11, 2010 Slide 23

23 Main Applications for Shunt Reactors Stability / voltage control at light loads Q X Q Q X X Q U Voltage increase from capacitive generation 1 X Reactor restores voltage to specified value May 11, 2010 Slide 24

24 How we can contribute to a greener future Lower noise levels reduce disturbances in the close surrounding Measured sound power level versus manufacturing year Black column In the factory before delivery Blue column On site in 2007 Sound power level [db(a)] Manufacturing year ABB Reactors have low sound power from the factory and that level is kept during the operational life time of the reactors. No degeneration. May 11, 2010 Slide 25

25 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. May 11, 2010 Slide 26

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

26 ABB variable shunt reactors References 15 variable shunt reactors delivered during to Europe, North America and Africa. Example of regulating ranges: Mvar Mvar Mvar Mvar The units delivered are designed for 225 to 420 kv May 11, 2010 Slide 27

27 Summary N e u t r O L a T l C 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 May 11, 2010 Slide 28

Phase Shifting Transformers. Presented by

Phase Shifting Transformers. Presented by Phase Shifting Transformers Presented by Phase Shifting Transformers (PST s) (a.k.a. Phase Angle Regulators) VS φ S P V V S = X L L X L sin( φ φ ) L S VL φ L PST s are power flow control devices between