TCP 2014 Conference Bangkok, August 4, 2014 Siriluk Pumirat ( M.Sc .)

1. Grid integration of high proportion ofrenewable energy - Research trends and Germany’s suggested solutions - TCP 2014 Conference Bangkok, August 4, 2014 SirilukPumirat (M.Sc.)

2. Fraunhofer Institute for Wind EnergyandEnergy System Technology (IWES) • Competence Center Rotor Blades • Drive Engineering and System Technology • Support Structures • Turbine Simulation, Software Development andAerodynamics • Systems Engineering and Distribution Grids • Energy Economy andGrid Operation • Wind Farm Planningand Operation • Bioenergy System Technology • Control Engineering andEnergy Storage Systems • Marine Energy

3. Outline Timeline ofelectricalenergysystemstechnology Currentlyfacingproblems Suggestedsolutions Energymanagement Frequencycontrol Voltagecontrol Autonomousvoltagesourceinverters Conclusionandoutlook

4. Timeline ofelectricalenergysystemstechnology • Network problem! • Energyovercapacity • Uncontrolablethe large numberof DG • Lessnaturalresources • Energyharvesting • Alternative energy e.g. nuclearor hydropower • Renewableenergy (RE) • Investment of RE • Policy • Sell RE tomaingrid • Increasingofdecentralizedgenerations (DG)

5. Generation VS Consumption [GW] Howtomatchthedemandandsupply?

6. Suggestion 1.Energymanagement Max = 50.1 GW Max = 58.1 GW withloadmanagement Min = -63.6 GW Min = -105.1 GW Basic residual load Max = 57.3 GW Min = -60.7 GW Hence, thereisnoobviousdifferencebyusingstorages!! withloadmanagement & storage

7. Indirectmanagementby Definingbuying & sellingtarifsbased on estimateddata The comparisonbetween 3-step priceand real variable steppricehasbeeninvestigated. The real variable steppriceimprovesonly 2% deviationbetterthantheotherone. But theadministrationofthevaribleoneismuchhigher!!

8. Ifthegenerationandconsumption still not macht,What happen on thenetwork? • Frequencystability • New gridcodes • Virtual inertia • Voltagestability • Reactive power injection • Tap-changertransformer • Inteligentlocalcontrol • Decentralizedcontrolusingcommunicationtechnology

9. Suggestion 2. Frequencycontrol • Conventional frequency control • Primary Control: Range of seconds to minutes • Secondary Control: Range of minutes to hours • Tertiary Control: Range of hours to days • The current grid code • DGs contribute in terms of over/under frequency conditions Source: ENTSO-E Pilot Grid Code

10. Advanced Frequency Control ConceptChallenges in inverter-dominated grids • Influence of reduced rotating inertia • Replacement of rotating generators by inverters • System time constant TN will be reduced • Variable grid code • PV-systems contribute in terms of over/under frequency coditions A virtualinertiaisadded!!

11. Advanced Frequency Control ConceptSimulation results • Parameters • Load step of 2%, TN = 1s • Primary control activated • Advantages of Statim-Control • Fast reaction on frequency deviation • Increase of frequency minimum from 48.6 Hz to 49.25 Hz • Maximal dynamic frequency deviation of ± 800mHz is kept

12. Suggestion 3. Voltagecontrol • Grid voltage can be reduced if the reactive power is injected into the grid • If the voltage at the PCC is not exceed the limit, more inverters can be connected into the grid to feed further active power!!

13. Combination of different voltage regulation methods • Controllable Distribution Transformer with OLTC • Adjustable PV-inverter Source: T. Bülo et al., VoltageControl in Active, Intelligent Distribution Networks, PVSec, 2012

14. Controllable Distribution Transformer • Voltage set-point: 230V • Control band: 1.5% Withcontrol Withoutcontrol

15. Combination of different voltage regulation methodsTest setup

16. Combination of different voltage regulation methodsTest results • Sunny day • Cloudy day

17. Economic analysis of different voltage regulation methods • Investment, operationandextensionover 10 yearsperiod Source: „Techno-Economic Assessment of Voltage Con-trol Strategies in Low Voltage Grids“, T. Stetz

18. Suggestion 4.Autonomousvoltagesourceinverters • Gridcomponents • grid parallel components(loads, uncontrollable generators) • grid supporting components(contribute to primary control of the grid) • grid forming components(determine voltage &frequency of the grid) L L 1 2 d U U U U 1 2 1 2

19. Autonomousdroop-basedvoltagesourceinverters • Advantages • high redundancy due to exclusively applying voltage sources • no additional devices for communication and synchronisation • Disadvantages • possibility of currents exchanged between the inverters • complex control algorithms are required: • precise control with regard to magnitude and phase • fast active and reactive power acquisition is required

20. Conclusionandoutlook The suggestionstobalancegeneration/consumptionandgridsupportingareintroduced Peak loadscanbecoveredbytechniqueofloadmanagementandenergystorage DGs contribute nowadays to over-frequency and over-voltage situations Advanced frequency control concepts are required especially for replacement of rotating inertia Tosupportthegrid, varyingof P and Q injectioncanhelptomaintainthefrequencyandvoltage in thestabilitybands The concept of combining different voltage regulation methods is introduced and evaluated The autonomousvoltagesourceinvertersbased on droopshavea high potential forthedecentralizedgridstructure

21. Thank you for your attention! SirilukPumirat (M.Sc.) Fraunhofer IWES Königstor 59 34119 Kassel Phone: +49 561 7294 102 siriluk.pumirat@iwes.fraunhofer.de