1. Electric System Carlos Silva October 28 st 2009

2. Electric System Components Generation Transmission Network Substations Distribution Network Substations / Transformers Homes / Industry

3. ELECTRICITY GENERATION

4. Transforming energy to electricity Power Plant Transforms some type of energy to electric energy Circular motion from direct force (hydro, wind, waves) Circulation motion from direct steam using heating (thermal, nuclear) Photovoltaic panel Generators Transforms circular motion of the rotor into electricity

5. Electricity Generation France (>2000) USA (>2000) Portugal (2006)

6. Thermal Power Plants Power: 200 to 500 MW Efficiency: 33% to 48% Fuel: coal, natural gas, nuclear, oil, solar Sines (1,2GW) Thermal Power Plant diagram Taichung (4,7GW)

7. Geothermal Power Plant Ribeira Grande power: 14 MW Efficiency: <80% Ribeira Grande (14MW) Geothermal Diagram

8. Geothermal Power Plant Ribeira Grande power: 14 MW Efficiency: <40% Ribeira Grande (14MW) Geothermal Diagram

9. Hydro Power Plants Power: 100 MW to 14GW Efficiency: 90% Castelo Bode (140MW) Hydro Plant diagram Itaipu (14GW) Alqueva (240MW) Alto Lindoso (632MW)

10. Wind Power Plant Wind turbine power: 1 - 5MW MagLev: 1GW(?) Wind farm power: 10 – 300MW Betz efficiency: 59.6% Wind turbine efficiency: 30% Capacity factor: 20 - 40% Area: 5MW /hectare Copenhagen (40MW) Pampilhosa (81MW) Wind Turbine Diagram Wind Potential Europe

11. Wave Generator Turbine Using air flow created by waves to move a turbine Using wave to push water upwards and using a normal hydro power plant Hydraulic motor Transforming linear to circular motion Archimedes (AWS) Pico, Açores

12. Pelamis Generator Linear motion into circular motion Cylinders (linear) and hydraulic motor( circular)

13. Wave Power Plant Pelamis power: 0.75 MW Wave farm power: 2 – 20MW Efficiency: 25-40% Area: 30kW/ hectare Wave world potential PovoaVarzim (2,25MW)

14. Photovoltaic Power Plant Serpa (11MW) PV panel power: 150 W/m 2 PV plant power: 10 – 60MW Moura (62MW) PV panel efficiency: 20% Insolation: 4-7 kW/m 2 /day Area: 1MW/hectare Moura (62MW) Insolation year Plant diagram

15. ELECTRICITY TRANSMISSION

16. First commercial electric system (US) First distribution systems were DC (Thomas Edison) Electric load was essentially incandescent lamps (100V DC) Other systems (motors) required other voltages DC could be used wit storage batteries (used as backup) DC generators (110V) could be used in parallel to increase production capacity DC generators had to be within 2.4km (1.5mile) from users Different voltages required different generators Edison had invented an electric meter (DC) First light bulb Thomas Edison

17. Tesla invents the AC electric system AC shows up on 1880 (George Westinghouse) AC could be generated with higher efficiencies AC could be transmitted over larger distances It was easier to increase and decrease voltages (transformation) Risks were similar Nikola Tesla George Westinghouse

18. War of currents Edison makes a negative campaign AC was more danger Harold P. Brown, Edison’s employee, developed the first electric chair (AC) Niagara Falls Commission contract (1893) Edison + General Electric lost against George Westinghouse + Tesla 1896 generation started to Buffalo industries AC became the standard on 1900 Helsinki had a DC system until 1940 Boston, Massachusetts had DC systems until 1960 1998, Consolidated Edison (New York) started eliminating remaining systems (2007) DC is still used for transmission (HVDC)

19. Transmission Between Power Plant and Substation High way of electricity Long distance connections Usually takes place above 110kV Overhead lines or underground lines Underground lines costs are 10 to 20 times higher Maintenance in underground lines is much more expensive Difficulties in voltage management due to reactive power Magnetic field range is smaller

20. Losses Losses are due to Joule heating Electric energy transformed into thermal energy (incandescent lamps) These losses are proportional to current and wire resistance For the same power, higher voltages means less current Transporting energy in higher voltage decreases losses They usually represent between 5 to 10% of transmitted power

21. Power Station Decrease very high voltage to high voltage (60kV, 30KV)

22. Transformers Two coils with different number of spirals

23. HVDC systems High Voltage Direct Current Develop din Sweden in 1930’s Less infrastructure costs Less transmission losses Used for very long distances Inga-Kolwesi connecting Inga-Dam and cooper mining in Katanga (1700km) Used to connect different AC systems Brazil (60Hz) and Paraguay(50Hz) electricity produced at ITAIPU Undersea cables Interconnection between Philippines between islands produced by geothermic Inga-Kolwesi

24. ELECTRICITY DISTRIBUTION

25. Distribution Between power stations and homes Reduce 60kV/30KV to 15, 10, 5KV Distribution pole High Voltage (60kV) Grid - Lisbon

26. Load Curve Amount of electricity requested by customers The amount of produced electricity has to be equal to the demand Hard to obtain when the production is variable (renewables) São Miguel load curve

27. Residential Consumption Portugal (DGEG -2004)

28. Family with four persons