Varspeed Pump Storage Power Plants: Technology and Operation

Transcription

1 February 2006 Varspeed Pump Storage Power Plants: Technology and Operation Dr. Alexander Schwery

2 Content of the Presentation PSP Changing Environment Advantages of Varspeed Concept of Varspeed Technology Improvements in Power Electronics Generator Technology for Varspeed Optimization Process Conclusions 2

3 Content of the Presentation PSP Changing Environment Advantages of Varspeed Concept of Varspeed Technology Improvements in Power Electronics Generator Technology for Varspeed Optimization Process Conclusions 3

4 History and Purpose of PSPs First units built at the beginning of last century Main developments started after second WW large number of nuclear power plants Production consumption balance on a daily and seasonal level World wide Europe wide 4

5 Network Stability and PSPs consumption grid frequency production Environmental regulations (Kyoto) 36 GW of wind power in Germany, Spain, Netherlands and Denmark No new nuclear power plant in the last 15 years Separation between power producer and network operator / tougher economical environment 5

6 Turbine PSP Technology Evolution of SWEP Index (CHF/MWH) 400 CHF 300 CHF ~ 150 Days 200 CHF 100 CHF ~ 150 Days CHF 200 CHF 100 CHF Trend to higher price Trend to higher volatility ~150 Days 6

7 PSP changing environment Conclusions Difficult to forecast market evolution Trend is towards higher price higher volatility Fast adaptation to new requirements is key Infrastructure providing additional flexibility can be an important asset 7

8 Content of the Presentation PSP Changing Environment Advantages of Varspeed Concept of Varspeed Technology Improvements in Power Electronics Generator Technology for Varspeed Optimization Process Conclusions 8

9 Turbine PSP Technology Heads below 600m Maximum / minimum head ratio below 1.25 Single stage Reversible Francis Turbine units 9

10 Turbine PSP Technology Heads above 700m Maximum / minimum head ratio below 1.25 Multistage Reversible Francis Turbine units 10

11 Varspeed Turbine Mode Maximum / minimum head ratio above 1.25 Increased Efficiency in Turbine Mode Pump characteristics Turbine characteristics Head η Head Hmax Hmin α omin α omax Flow Flow 11

12 Varspeed Pump Mode Maximum / minimum head ratio above 1.25 Adjustable power absorption in pump mode Head H max. Stability N 3 P max. N synch. η max. H example Kavitation N 1 H min. Flow 12

13 Varspeed Example Potential Installation in Switzerland: Despite the rather low max / min ratio of 1.25 Average increase of turbine efficiency of 1% During 80% of the operation time the power variation range is higher than 20% 1pu 39 Relative Efficiency in Turbine Mode fixed speed variable speed Pump Power MW head limits ± 4 % Domain.9 pu Turbine Power in MW Head m 13

14 Varspeed Example 100 SHA HE 2 x 51MW K = 850 K = 600 AFOURER UR2 2 X 60.15MW LAM TA KON G 4 x 263 MW SPECIFIC SPEED : n.q 1/2 / H3/4 (r.p.m. - m3/s - m) TAN ES 2 x 66.5 MW K = 400 BAILIANHE LE CHEYLAS 2 x 252 MW SANCHONG 4 x 306 MW YECHEON REVIN 4 x 188MW ZHANGHEWAN 4 x 255MW Tajo de la Encantada 4 x 92MW 2 x 390 MW MONTEZIC 4 x 212MW BAOQUAN 4 x 306 MW LE TRUEL 1 x 37 MW 2 x 408 MW MUJU 2 x 335 MW GUANGZHOU 4 x 347 MW BENI HAROUN 2 x 92MW AFOURER UR1 2 x 175.6MW HUIZHOU 4 x 306 MW YANG YANG 4 X 270 MW VILARINHO 1 x 63.8MW EAU D'OLLE 8 x 156 MW PUMP HEAD (m)

15 Varspeed vs. Fixed Speed Comparison turbine mode: two fixed speed / two varspeed units, same output 200 % 140 % 100 % 70 % time instantaneous power tracking / fewer starts and stops 15

16 Varspeed Network Stability 50 % Voltage drop on Network Fixed Speed After elimination of fault pronounced oscillation of machine speed speed [p.u.] Time [s] Varspeed Asynchronous machine returns very fast to initial speed and helps stabilizing the network speed [p.u.] Time [s] 16

17 Varspeed Network Stability Instantaneous Power injection/absorption Change of speed speed [p.u.] 0.95 Kinetic energy is injected / absorbed to / from the network Possible to react on step changes in load Time [s] i a [p.u.] Time [s] 17

18 Advantages of Varspeed Conclusions For maximum / minimum head ratios above 1.25 Main advantages of varspeed controlled power absorption in pump mode varspeed psp higher efficiency in turbine mode Further advantages fewer starts and stops critical zones (vibration/cavitation) can be avoided increased network stability 18

19 Content of the Presentation PSP Changing Environment Advantages of Varspeed Concept of Varspeed Technology Improvements in Power Electronics Generator Technology for Varspeed Optimization Process Conclusions 19

20 Concept of Varspeed Technology Synchronous Machine Speed directly linked to stator frequency n = f s / p Power electronic necessarily on the stator Economically reasonable only for small units 20

21 Concept of Varspeed Technology 12 pulse LCI T n Speed range depends only on pump capability 21

22 Concept of Varspeed Technology Induction Machine Speed linked to rotor frequency s = (f s -n) /f s n = f s -sf s =f s -f r Power electronics on rotor circuit Economically reasonable only for large units 22

23 Concept of Varspeed Technology Direct / Cyclo Converter T n Speed range defines necessary power electronics power 23

24 300 MW Variable Speed Drives 2 x 331 MVA / rpm SM 2 x 331 MVA / +4 / -10 % rpm IM Maximum dam level Minimum level Amount of exchanged water Maximum dam level Minimum level 24

25 Content of the Presentation PSP Changing Environment Advantages of Varspeed Concept of Varspeed Technology Improvements in Power Electronics Generator Technology for Varspeed Optimization Process Conclusions 25

26 Varspeed Technology PE Cyclo converters : Starting SFC required Harmonics Reactive power consumption Overload capabilities Voltage source inverters : Fewer elements Can be used for start up Higher switching frequency 26

27 Varspeed Technology PE Cyclo converter Voltage source inverter 1 E E E E [p.u] E-2 [p.u] [p.u] E E Harmonics in [Hz] with a fundamental Time frequency [s e c] of 5 Hz - THD (50 Hz) = % - 1 E Harmonics in [Hz] with a fundamental Time [s frequency e c] of 5 Hz - THD (50 Hz) = % 27

28 Cyclo vs. VSI Cyclo converter Voltage source inverter 28

29 Cyclo vs. VSI Cyclo converter Voltage source inverter 29

30 Content of the Presentation PSP Changing Environment Advantages of Varspeed Concept of Varspeed Technology Improvements in Power Electronics Generator Technology for Varspeed Optimization Process Conclusions 30

31 Varspeed Generator Technology Synchronous- Motor/Generator Asynchronous- Motor/Generator 31

32 Varspeed Generator Technology Technical Challenges Rotor yoke mechanical stress electrical losses 32

33 Varspeed Generator Technology Technical Challenges Rotor Winding Overhang centrifugal forces 33

34 Varspeed Generator Technology Double fed asynchronous machines Induction machine with three phase winding on rotor Approved technology in rotating converters between railway network and power network 1 ph. / 16 2/3 Hz 3 ph. / 50 Hz 34

35 Content of the Presentation PSP Changing Environment Advantages of Varspeed Concept of Varspeed Technology Improvements in Power Electronics Generator Technology for Varspeed Optimization Process Conclusions 35

36 Product development Process Conventional PSP CUSTOMER Levels Flow Turbine Design Speed Inertia Generator Design Schedules $$$ Straight forward process without iterations Individual steps can be done in standalone 36

37 Product development Process Varspeed PSP CUSTOMER Iterative optimization process 37 Schedules $$$ Levels Flow Efficiency Power Range Turbine Design Individual steps need to be coordinated Overall process knowledge required Speed Speed Range Inertia Generator Design PE Design PE Power Rotor Voltage Voltage ratio

38 Content of the Presentation PSP Changing Environment Advantages of Varspeed Concept of Varspeed Technology Improvements in Power Electronics Generator Technology for Varspeed Optimization Process Conclusions 38

39 Conclusion Important ecological and economical influence on the power production and distribution Stability and power balance are key issues PSPs are the most efficient way of stocking large amounts of energy Variable speed technology can provide a valuable contribution to these needs Technological improvements in power electronics make variable speed solutions more competitive Varspeed needs a system approach 39

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41 Varspeed Technology Two speed Generators / pole commutable machines Some poles can have inverse polarity Resulting in two numbers of poles and therefore synchronous speeds Only two possible speeds Two independent stator windings Complex commutation circuit breakers 41

42 Vorteile Spannungsumrichter 1 1 E E-1 [p.u] 0 [p.u] E Time [s e c] E Harmonics in [Hz] with a fundame ntal frequency of 5 Hz - THD (50 Hz) = % 1 1 E E-1 [p.u] 0 [p.u] E Time [s e c] E Harmonics in [Hz] with a fundamental frequency of 5 Hz - THD (50 Hz) = % Empty box animated 42

43 Turbine PSP Technology 43