Impact of growing renewable energy generation onto thermal power plant operation in Germany

Transcription

1 Impact of growing renewable energy generation onto thermal power plant operation in Germany July 7 th 9 th ECM3, Aberdeen Dipl.-Ing. Christian Ziems Prof. Dr. Harald Weber Dr.-Ing. Sebastian Meinke (Vattenfall R&D) Dr.-Ing. Ibrahim Nassar Dipl.-Ing. Matthias Huber (TU Munich) Institute of Electrical Power Engineering & Department of Technical Thermodynamics University of Rostock 08/12/ UNIVERSITÄT ROSTOCK 1

2 Motivation, Goals and Challenges Transition to renewable energy sources Motivation: Substitute the limited fossil fuels with unlimited renewable energy sources Massive reduction of the CO 2 emissions Stop the production of nuclear waste Eliminate the threat of nuclear accidents like Fukushima 2011 Goals: Reduce the CO 2 emissions up to 80% until 2050 in Germany Nuclear phase-out planned until the end of 2022 Increase the total fraction of all renewables sources up to 45% of the electrical energy demand until 2025 and up to 80% until 2050 Challenges: Use as much renewable power as possible directly when it is produced To achieve the highest efficiency of the potentials Due to the high losses of storage systems store only as much as necessary Problem of power transmission because of limitations of the transmission lines etc. Problem of balancing power of intermittent sources by thermal power plants Guarantee the safety of supply 08/12/ UNIVERSITÄT ROSTOCK 2

3 Motivation, Goals and Challenges Transition to renewable energy sources controlled power production of fossil and (nuclear) power plants with limited fuels, nuclear waste & high CO 2 emissions fuel: lignite, hard coal, natural gas, Uranium Power plant operation depends on intermittent feedin uncontrolled power production of wind and photovoltaic systems with intermittent feed-in (not reliable) Wind turbines Situation 2014: 34 GW expected 2020: 50+ GW Integration of intermittent feedin depends on flexibility of conv. Power plants Photovoltaic systems Situation 2014: 36 GW expected 2020: 50+ GW Goal: - massive reduction of CO 2 emissions - nuclear phase-out until 2022 Expected installed capacity until 2020: >100 GW (>33% of annual electricity demand) 08/12/ UNIVERSITÄT ROSTOCK 3

4 Expected growth of installed capacities of German wind turbines & photovoltaic systems 70,0 GW Wind onshore Wind offshore Peak load in Germany: app. 80 GW (expected to remain constant) Expected installed power until ,0 GW Installed capacity PV 60,0 GW 50,0 GW 40,0 GW 30,0 GW 20,0 GW Installed 2020: Wind PV 51,0 GW + 51,7 GW Σ102,7 GW 60,0 GW 50,0 GW 40,0 GW 30,0 GW 20,0 GW 10,0 GW 10,0 GW 0,0 GW ,0 GW ,0 TWh Consumption in Germany 2011: app. 600 TWh (expected to remain constant) Wind onshore Wind offshore Expected energy to be harvested until ,0 TWh PV Einspeisung 180,0 TWh 160,0 TWh 140,0 TWh 120,0 TWh 100,0 TWh 80,0 TWh 60,0 TWh 40,0 TWh 20,0 TWh Annual harvest 2020: Wind PV 138,8 TWh + 54,2 TWh Σ193 TWh 60,0 TWh 50,0 TWh 40,0 TWh 30,0 TWh 20,0 TWh 10,0 TWh 0,0 TWh ,0 TWh /12/ UNIVERSITÄT ROSTOCK 4

5 Capacities of renewable energy from wind and solar systems expected until 2025 in Germany 140,0 GW Wind onshore Wind offshore PV Max. load 120,0 GW 100,0 GW 80,0 GW 60,0 GW 40,0 GW 20,0 GW 0,0 GW /12/ UNIVERSITÄT ROSTOCK 5

6 Combinations of different load and intermittent feed-in (non-dispatchable feed-in) In the past (2008) In the Future (2020) Winter period in January Leistung in MW Residual load provided by dispatchable plants Leistung in MW Summer period in May/June Leistung in MW Residual load provided by dispatchable plants Leistung in MW Hydro (run-of-river) Combined-Heat&Power (CHP) Photovoltaic (PV) Offshore Wind Onshore Wind Residual Load Total demand (load) 08/12/ UNIVERSITÄT ROSTOCK 6

7 Transition of the power system into a renewable system A simplified scheme of the power balance of the generation system Non-dispatchable feed-in Dispatchable generation Thermal Power Plants & Pumped Storage One node network model + P dispatchable + Residual load P residual load P non-dispatchable Wind and PV (CHP & Hydro) P load + - Always Zero, Frequency f is indicator of power balance Consumers Actually no Demand Side Management 08/12/ UNIVERSITÄT ROSTOCK 7

8 Resulting annual residual load curve 80 Power Power demand [GW] in GW Requirements for backup power >50 GW will remain Residual load curve is shifted Increasing generation surplus has to be exported or stored Hours 08/12/ UNIVERSITÄT ROSTOCK 8

9 Merit Order Method (example prices) Source: DI Dr. Gero old Petritsch, University of Vienna, Faculty of Mathematics Production costs in Euro/MWh One hour oriented Day-Ahead- Scheduling Run-of-river and storage water Nuclear energy Current power demand Lignite Pumped storage power Hard coal Oil and Hard coal gas turbines Gas Optimization goal: Meet the demand at any time with minized production costs Cumulated installed electrical power in GW 00:00 01:00 02:00 08/12/ UNIVERSITÄT ROSTOCK 9

10 Flexibility assumptions for scenarios ofdifferent thermal types (referstotheratedpower) 100% 80% 5,0% 5,0% 5,0% 2,5% 2,5% 10,0% 10,0% 10,0% + P primary control operation point 60% 40% 10,0% 5,0% 10,0% 5,0% 10,0% 5,0% 2,5% 2,5% +/-50,0% + P secondary control P schedule - P secondary control - P primary control 20% 55,0% 50,0% 60,0% 60,0% 30,0% minimum load if control enabled 0% Lignite Hard coal CCPP Nuclear Gasturbines 08/12/ UNIVERSITÄT ROSTOCK 10

11 Resulting generation structure in Germany Percentage basis referred to net electr. generation Industrial incl. CHP 8,0% Industrial incl. CHP 7,5% Nuclear 0,0% Hydro 4,1% Renewables w/o biomass: 19 % PV 4,1% Wind 10,8% natural gas w/o CHP 3,4% CHP general 10,0% Hard coal 18,2% 2011 Nuclear 17,1% Lignite 24,3% Net electr. generation: 587,4 TWh --> thereof surplus: 0 TWh --> thereof export: 18,3 TWh Hydro 3,9% Renewables w/o biomass: 40 % CHP general 14,5% Wind 26,1% 2023 Lignite 20,1% PV 9,6% Hard coal 16,6% Net electr. generation: 625,1 TWh --> thereof surplus: 4,5 TWh --> thereof export: 50,5 TWh natural gas w/o CHP 1,7% 08/12/ UNIVERSITÄT ROSTOCK 11

12 Displacementofconventionalpower Exemplary power plant scheduling for one week Leistung in MW 90 Winter ,0 P_PV Consumption P_Gesamtlast Germany P_Wind_onshore ,0 Residual_load load P_Wind_offshore ,0 Photovoltaic P_PV P_KWK (PV) ,0 Onshore P_Wind_onshore P_Wasser Power in GW , , , , ,0 0 0, , ,0 Offshore P_Wind_offshore import Combined P_KWK PSW_turb Heat & Power (CHP) Run-of-river P_Wasser GuD Pumped PSW_turb SKW Storage Turbine Mode Combined GuD BKW Cycle Power Plant (CCPP) Hard SKW KKWcoal Lignite BKW surplus Nuclear KKW PSW_pump Surplus surplus export Days Ausgewählte Tage Pumped PSW_pump P_Gesamtlast Storage Pump Mode Residual_load 08/12/ UNIVERSITÄT ROSTOCK 12

13 Displacementofconventionalpower Exemplary power plant scheduling for one week Leistung in MW 90 Winter ,0 P_PV Consumption P_Gesamtlast Germany P_Wind_onshore ,0 Residual_load load P_Wind_offshore ,0 Photovoltaic P_PV P_KWK (PV) ,0 Onshore P_Wasser P_Wind_onshore ,0 Offshore import P_Wind_offshore ,0 PSW_turb P_KWK Run-of-river GuD P_Wasser ,0 PSW_turb SKW Power in GW , ,0 0 0, , ,0 Ausgewählte Tage Combined Heat & Power (CHP) Pumped Storage Turbine Mode Combined GuD BKW Cycle Power Plant (CCPP) Hard SKW KKWcoal Lignite BKW surplus Nuclear KKW PSW_pump Surplus surplus export Days Pumped PSW_pump P_Gesamtlast Storage Pump Mode Residual_load 08/12/ UNIVERSITÄT ROSTOCK 13

14 Displacementofconventionalpower Exemplary power plant scheduling for one week Leistung in MW 90 Winter ,0 P_PV Consumption P_Gesamtlast Germany P_Wind_onshore ,0 Residual_load load P_Wind_offshore ,0 Photovoltaic P_PV P_KWK (PV) ,0 Onshore P_Wasser P_Wind_onshore ,0 Offshore import P_Wind_offshore ,0 PSW_turb P_KWK Run-of-river GuD P_Wasser ,0 PSW_turb SKW Power in GW , ,0 0 0, , ,0 Ausgewählte Tage Combined Heat & Power (CHP) Pumped Storage Turbine Mode Combined GuD BKW Cycle Power Plant (CCPP) Hard SKW KKWcoal Lignite BKW surplus Nuclear KKW PSW_pump Surplus surplus export Days Pumped PSW_pump P_Gesamtlast Storage Pump Mode Residual_load 08/12/ UNIVERSITÄT ROSTOCK 14

15 Displacementofconventionalpower Exemplary power plant scheduling for one week Leistung in MW 90 Winter ,0 P_PV Consumption P_Gesamtlast Germany P_Wind_onshore ,0 Residual_load load P_Wind_offshore ,0 Photovoltaic P_PV P_KWK (PV) ,0 Onshore P_Wasser P_Wind_onshore ,0 Offshore import P_Wind_offshore ,0 PSW_turb P_KWK Run-of-river GuD P_Wasser ,0 PSW_turb SKW Power in GW , ,0 0 0, , ,0 Ausgewählte Tage Combined Heat & Power (CHP) Pumped Storage Turbine Mode Combined GuD BKW Cycle Power Plant (CCPP) Hard SKW KKWcoal Lignite BKW surplus Nuclear KKW PSW_pump Surplus surplus export Days Pumped PSW_pump P_Gesamtlast Storage Pump Mode Residual_load 08/12/ UNIVERSITÄT ROSTOCK 15

16 Displacementofconventionalpower Exemplary power plant scheduling for one week Leistung in MW 90 Summer ,0 P_PV Consumption P_Gesamtlast Germany P_Wind_onshore ,0 80 Residual_load load P_Wind_offshore ,0 70 P_KWK Photovoltaic P_PV (PV) Power in GW , , , , , ,0 0 0, , ,0 P_Wasser Onshore P_Wind_onshore import Offshore P_Wind_offshore PSW_turb Combined P_KWK Heat & Power (CHP) GuD Run-of-river P_Wasser SKW Pumped PSW_turb Storage Turbine Mode BKW Combined GuD Cycle Power Plant (CCPP) KKW Hard SKWcoal surplus Lignite BKW PSW_pump Nuclear KKW export Surplus surplus Days Ausgewählte Tage P_Gesamtlast Pumped PSW_pump Storage Pump Mode Residual_load 08/12/ UNIVERSITÄT ROSTOCK 16

17 Displacementofconventionalpower Exemplary power plant scheduling for one week Leistung in MW 90 Summer ,0 P_PV Consumption P_Gesamtlast Germany P_Wind_onshore ,0 80 Residual_load load P_Wind_offshore ,0 70 P_KWK Photovoltaic P_PV (PV) Power in GW , , , , , ,0 0 0, , ,0 P_Wasser Onshore P_Wind_onshore import Offshore P_Wind_offshore PSW_turb Combined P_KWK Heat & Power (CHP) GuD Run-of-river P_Wasser SKW Pumped PSW_turb Storage Turbine Mode BKW Combined GuD Cycle Power Plant (CCPP) KKW Hard SKWcoal surplus Lignite BKW PSW_pump Nuclear KKW export Surplus surplus Days Ausgewählte Tage P_Gesamtlast Pumped PSW_pump Storage Pump Mode Residual_load 08/12/ UNIVERSITÄT ROSTOCK 17

18 Displacementofconventionalpower Exemplary power plant scheduling for one week Leistung in MW 90 Summer ,0 P_PV Consumption P_Gesamtlast Germany P_Wind_onshore ,0 80 Residual_load load P_Wind_offshore ,0 70 P_KWK Photovoltaic P_PV (PV) Power in GW , , , , , ,0 0 0, , ,0 P_Wasser Onshore P_Wind_onshore import Offshore P_Wind_offshore PSW_turb Combined P_KWK Heat & Power (CHP) GuD Run-of-river P_Wasser SKW Pumped PSW_turb Storage Turbine Mode BKW Combined GuD Cycle Power Plant (CCPP) KKW Hard SKWcoal surplus Lignite BKW PSW_pump Nuclear KKW export Surplus surplus Days Ausgewählte Tage P_Gesamtlast Pumped PSW_pump Storage Pump Mode Residual_load 08/12/ UNIVERSITÄT ROSTOCK 18

19 Displacementofconventionalpower Exemplary power plant scheduling for one week Leistung in MW 90 Summer ,0 P_PV Consumption P_Gesamtlast Germany P_Wind_onshore ,0 80 Residual_load load P_Wind_offshore ,0 70 P_KWK Photovoltaic P_PV (PV) Power in GW , , , , , ,0 0 0, , ,0 P_Wasser Onshore P_Wind_onshore import Offshore P_Wind_offshore PSW_turb Combined P_KWK Heat & Power (CHP) GuD Run-of-river P_Wasser SKW Pumped PSW_turb Storage Turbine Mode BKW Combined GuD Cycle Power Plant (CCPP) KKW Hard SKWcoal surplus Lignite BKW PSW_pump Nuclear KKW export Surplus surplus Days Ausgewählte Tage P_Gesamtlast Pumped PSW_pump Storage Pump Mode Residual_load 08/12/ UNIVERSITÄT ROSTOCK 19

20 Increasing capacityofwind andsolar generators: Change ofsinglethermal power plant operationandutilization Project /12/ UNIVERSITÄT ROSTOCK 20

21 Limits of a thermal power plant Variation of different flexibility parameters Load gradient Scenarios 2.5%, 4%, 6% Grad max Lastgradient P min operation parameters Simulate different operation modes Min load scenarios 50%, 37.5%, 33%, 20 % Mindestlast Simulation of critical load and intermittent scenariosundervariationofloadgradient, min loadofpp Rostock oroperationofthepower plant in unconventional partial load special operation modes shut down & restart reduce to circulation mode Stillstand 08/12/ UNIVERSITÄT ROSTOCK 21

22 Compared Flexibility Options (TPP Rostock) Pmax=500MW net, eta=43.2%, hard coal, comm. In % 80% 5,0% 5,0% 5,0% 10,0% 20,0% 20,0% + P primary control + P secondary control Operation point 60% 40% 20% 0% 10,0% 5,0% 20,0% 5,0% 35,0% 35,0% Flex today Ramping: 2%/min FlexOption 1 4%/min Optimization in existing plant 20,0% 5,0% 25,0% FlexOption 2 4%/min For new plants P schedule - P secondary control - P primary control unconventional sector technical minimum load Unconventional sector: If primary and secondary control is used this operation point normally is not used due to coal mill switching Potential for optimization to achieve higher flexibility 08/12/ UNIVERSITÄT ROSTOCK 22

23 Results for Flex today Without enhanced flexibility Operation poin nt Flexibility in this case 100% 80% 60% 40% 20% 0% 5,0% 10,0% 10,0% 5,0% 35,0% Flex today Ramping: 2%/min num mber of start-ups Annual start-up cycles Flex today Flex today Flex today cold start warm start hot start specific 1,9 19,3 16,6 80,0 60,0 40,0 20,0 0,0 specific starts each 1000 full load h power in MW Annual partial load operation 2011 Flex today 2020 Flex today 2023 Flex today annual operating hours hours Annual full load and operating hours Flex today Flex today Flex today full load hours operating hours /12/ UNIVERSITÄT ROSTOCK 23

24 Results for Flex Option 1 With enhancements in the existing plant Operation poin nt Flexibility in this case 100% 80% 60% 40% 20% 0% 5,0% 20,0% 20,0% 5,0% 35,0% FlexOption 1 4%/min num mber of start-ups Annual start-up cycles Flex today Flex Option 1 Flex Option 1 cold start warm start hot start specific 1,9 13,2 7,7 80,0 60,0 40,0 20,0 0,0 specific starts each 1000 full load h power in MW Annual partial load operation 2011 Flex today 2020 FlexOption FlexOption annual operating hours hours Annual full load and operating hours Flex today Flex Option 1 Flex Option 1 full load hours operating hours /12/ UNIVERSITÄT ROSTOCK 24

25 Results for Flex Option 2 With enhanced design parameters for new plants Operation poin nt Flexibility in this case 100% 80% 60% 40% 20% 0% 5,0% 20,0% 20,0% 5,0% 25,0% FlexOption 2 4%/min num mber of start-ups Annual start-up cycles Flex today Flex Option 2 cold start 0 0 warm start 11 5 hot start 3 1 specific 1,9 1,6 80,0 60,0 40,0 20,0 0,0 specific starts each 1000 full load h Annual partial load operation Annual full load and operating hours power in MW Flex today 2023 FlexOption annual operating hours hours Flex today Flex Option 2 full load hours operating hours /12/ UNIVERSITÄT ROSTOCK 25

26 Investigation of power plant schedules Hourly resolution(examplethermal Plant Rostock) 500 Minimum load Neg. primary res Neg. secondary res Pos. secondary res Pos. primary res Scheduled setpoint elec ctrical power output in MW time 08/12/ UNIVERSITÄT ROSTOCK 26

27 Results for annual ordered utilization lignite fired power plant 2015/2025 No information for load step frequency evaluation in this figure type 08/12/ UNIVERSITÄT ROSTOCK 27

28 Results for annual utilization Annually ordered load change steps(weeks over the year) 08/12/ UNIVERSITÄT ROSTOCK 28

29 Results for annual utilization Annually ordered load change steps(weeks over the year) 08/12/ UNIVERSITÄT ROSTOCK 29

30 Results for annual pos. Reserves Annually ordered reserved power (weeks over the year) Tertiary Secondary Primary 08/12/ UNIVERSITÄT ROSTOCK 30

31 Results for annual pos. Reserves Annually ordered reserved power (weeks over the year) Tertiary Secondary Primary 08/12/ UNIVERSITÄT ROSTOCK 31

32 Detection of Restrictions overview 50% Degradation of the regulating 4% capabilities due to low mass flow rates Shut down of coal mills Low exhaust temperature prior DENOX Pressure deviations in the furnace due to low regulation capabilities of the forced draft fan 34% 20% Switch over to circulation mode Life steam temperature decreases which cause thermal stress cycles Low primary air temperatures in coal mills Single feed water pump operation 2% Regulating capabilites of the coal mills is restrictive Increasing fatigue due to temperature deviations lowering minimum load enhanced load gradient 08/12/ UNIVERSITÄT ROSTOCK 32

33 Possible Optimizations Identification & quantification 50% 34% Modified control parameters for low partial load Analysis of the potential of map based coal mill control and coal dust mass flow rate Optimization of the switch events (1/2 Pump operation, on/off switching of coal mills and change from circulation to Benson operation) 4% potential by expanding the data basis, e.g. map based determination of heating value, measurement of coal dust mass flow Optimization of the control parameters, e.g. dynamic of the ratio fuel rate to feed water mass flow Investigation of the circulation mode as an alternative operation to shut down and restart 20% 2% lowering minimum load enhanced load gradient 08/12/ UNIVERSITÄT ROSTOCK 33

34 Overview of dynamic power plant model Scope of Power Plant Model Water steam cycle from feed watertank until condenser, including start up devices steamair preheater exhaust gas air preheater mill fan air preheater coal coal mills evaporator HPB economizer reheater 1 cyclone superheater 3 start bottle reheater 2 HP circula- tion pump superheater 4 superheater 2 superheater 1 IP LP IPB to condensor to LPP Air Duct from forced draft fan until air preheater exhaust gas outlet reproduction of the independent coal mills and of combustion with regard to the coal composition reduced copy of the Control system including control forfuelmassflowrate, feedwaterpump, spray attemporators, coal mills, circulation cycle, turbine bypassandforceddraftandmillfan Can be operated with arbitrary load schedule Modeling of: fresh air forced draft fan firing Structure of the power plant model HPP feed water pump from feed water tank Temperature distribution in thick walled components fatigue investigations Calculation of process parameters (e.g. DENOXinlet temperature, efficiency, etc.) Modular structure enables model extension or substitution of components (e.g. simple Implementation of new control concepts) 08/12/ UNIVERSITÄT ROSTOCK 34

35 Demonstration scenario: 12 h of load schedule operation Results of power plant simulation Power plant Rostock P elek P elek Net-power t Load schedule t Component fatigue Creation of an fictitious load schedule with load set points between 37 % und 100% load Model calculates the resulting generator output Benchmark of the operation mode evaluation of component fatigue for the corresponding basic operation, e.g. Start or schedule load change/step 08/12/ UNIVERSITÄT ROSTOCK 35

36 Presentation of the base scenario of the evaluation Sekundärregelsignal Industrie Gewerbe Last Haushalte Netzregelmodell Kraftwerk Rostock Windeinspeisung Netto-Leistung Fahrplan Windkraftanlagen Structure of Base scenario coupling of the detailed model of power plant Rostock with simplified model of the rest power plant fleet in the control area application of a load schedule (from power plant scheduling model) input of a critical load and wind scenario evaluation of secondary reserve demand from power difference in the control area Kohle Kernenergie Gas 08/12/ UNIVERSITÄT ROSTOCK 36

37 Derivation of compare scenario P elek power plant Rostock load schedule t P elek P elek net power t secondary reserve signal t Grad max P min type of coal automation control types of operation Variation der used coal Implementation of optimized automation control usage of different operation parameters 08/12/ UNIVERSITÄT ROSTOCK 37

38 Influenceofdecreasinginertia: A shortintroductioninto power systemcontrol Project /12/ UNIVERSITÄT ROSTOCK 38

39 Control of Electrical Power Systems Accelerationpower of Inertias of conventional Power Plants Time constant T N =2*H N : today T N =10s-15s Primarycontrol (Load-Frequency Control In rotating machines +/-3.000MW ENTSO-E +/-610MW GER Secondarycontrol In rotating machines +/ MW GER Tertiary Control Minutereserve and Intra day (not) rotating MW GER MW GER Tertiary Control Day ahead Planing Milliseconds Seconds 15 Minutes Hours H N = 1 J Ω 2 P N 2 N Time frame 08/12/ UNIVERSITÄT ROSTOCK 39

40 Development ofthetime constantt N in the Entso-e-system ENTSO-E-System 08/12/ UNIVERSITÄT ROSTOCK 40

41 Case 1: Winter 2011 (0% Wind andpv) TN = 10,6 s CHP HPP CCPP Hard coal Lignite nuclear t CCPP Hard SKWcoal Primary control positive nuclear lignite hard coal CCPP GT Primary control negative nuclear lignite hard coal CCPP GT 08/12/ UNIVERSITÄT ROSTOCK 41

42 Case 2: Winter 2011 (47% Wind andpv) TN = 5,7 s Wind CHP HPP Lignite coal nuclear Hard coal Hard coal Lignite Primary control positive nuclear lignite hard coal CCPP GT Primary control negative nuclear lignite hard coal CCPP GT 08/12/ UNIVERSITÄT ROSTOCK 42

43 Case 3: Sommer 2023 (81% Wind andpv) TN = 2,1 s Solar Wind onshore Wind offshore CHP GPPs/CCGPPs HPP Hard coal Lignite GTPPs CCPPs Hard coal Lignite Primary control positive nuclear lignite hard coal CCPP GT Primary control negative nuclear lignite hard coal CCPP GT 08/12/ UNIVERSITÄT ROSTOCK 43

44 Simulated Frequency Cases /12/ UNIVERSITÄT ROSTOCK 44

45 Measurements in the Irish Network System frequency begins to oscillate due to reduced inertia 26 of December 2014 at 10:38 pm Due to a changed strategy of power plant operation from partial load with several thermal power stations to only a few near full load, inertia was reduce to level that the systems startet to oscillate Fraction of Wind 37% Only a few turbo-generators left Unit C30 Trip at 22:38 MW; Hz 7 Min Oscillation Pk-Pk: ~ Hz Period of Osc: 15 s (0.066 Hz) Quelle: ESB, Electric Ireland 08/12/ UNIVERSITÄT ROSTOCK 45

46 Thank you for your attention! Department of Electrical and Electronic Engineering Department of Technical Thermodynamics Dipl.-Ing. C. Ziems Dr.-Ing. I. Nassar Prof. Dr.-Ing. H. Weber Dipl.-Ing. S. Meinke Dr.-Ing. J. Nocke Prof. Dr.-Ing. habil. E. Hassel 08/12/ UNIVERSITÄT ROSTOCK 46