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Flexibility needs in the future power system

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Power system flexibility relates to the ability of the power system to manage changes.
Solutions providing advances in flexibility are of utmost importance for the future power system. Development and deployment of innovative technologies, communication and monitoring possibilities, as well as increased interaction and information exchange, are enablers to provide holistic flexibility solutions. Furthermore, development of new methods for market design and analysis, as well as methods and procedures related to system planning and operation, will be required to utilise available flexibility to provide most value to society.
However, flexibility is not a unified term and is lacking a commonly accepted definition.
The flexibility term is used as an umbrella covering various needs and aspects in the power system. This situation makes it highly complex to discuss flexibility in the power system and craves for differentiation to enhance clarity. In this work, the solution has been to differentiate
the flexibility term on needs, and to categorise flexibility needs in four categories.
Here, flexibility needs are considered from over-all system perspectives (stability, frequency and energy supply) and from more local perspectives (transfer capacities, voltage and power quality). With flexibility support considered for both operation and planning of the power system, it is required in a timescale from fractions of a second (e.g. stability and frequency support) to minutes and hours (e.g. thermal loadings and generation dispatch) to months and years (e.g. planning for seasonal adequacy and planning of new investments).

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Flexibility needs in the future power system

  1. 1. Flexibility needs in the future power system Emil Hillberg - RISE, Sweden ISGAN webinar November 6th, 2019 1
  2. 2. Overview of ISGAN Annex 6 activity on Flexibility needs • What is power system flexibility? • Analysis of flexibility needs, resources and definitions • Categorization of flexibility needs • Flexibility needs in time and space • Summary Nov 2019 2ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM
  3. 3. To support communication within and outside the power system community, Annex 6 of ISGAN (The International Smart Grid Action Network) propose the categorization of flexibility needs What is power system flexibility? ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 3 Flexibility as a term is used as an umbrella covering various aspects  complicating the discussion on challenges and needs of the power system Flexibility relates to the ability of the power system to manage changes Nov 2019
  4. 4. ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 4 Trends of flexibility needs? Trends of flexibility needs 5 Trends influencing the powers system decreasing the carbon footprint from electric power production Decarbonisation transition from few and large, centralized, power plants to many smaller, decentralised, power production units Decentralisation increasingly integrated electricity markets, greater interconnection of previously independent grids, and more integrated energy systems including sector coupling extensive implementation of and dependency on information and communication technologies and solutions Digitalisation increasing demand for sustainable, affordable and accessible energy for all including increased electrification of e.g. industrial processes and transport Integration Inclusion Increased volatility and uncertainty of the production and availability of electricity operation and planning closer to the system limit : Nov 2019
  5. 5. Definition of flexibility ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 5 “the ability to adapt the planned development of the power system, quickly and at reasonable cost, to any change, foreseen or not, in the conditions which prevailed at the time it was planned.” 1995, CIGRE through the working group 37.10 “the extent to which a power system can modify electricity production or consumption in response to variability, expected or otherwise. In other words, it expresses the capability of a power system to maintain reliable supply in the face of rapid and large imbalances, whatever the cause.” 2011, International Energy Agency - IEA “the modification of generation injection and/or consumption patterns in reaction to an external signal (price signal or activation) in order to provide a service within the energy system.” 2014, EURELECTRIC “the ability to adapt to dynamic and changing conditions, for example, balancing supply and demand by the hour or minute, or deploying new generation and transmission resources over a period of years.“ 2016, Electric Power Research Institute - EPRI “the capacity of the electricity system to respond to changes that may affect the balance of supply and demand at all times.” 2018, Council of European Energy Regulators - CEER “all relevant characteristics of a power system that facilitates the reliable and costeffective management of variability and uncertainty in both supply and demand.” 2018, International Energy Agency - IEA “the capability of a power system to cope with the variability and uncertainty that VRE (variable renewable energy) generation introduces into the system in different time scales, from the very short to the long term, avoiding curtailment of VRE and reliably supplying all the demanded energy to customers”. 2018, International Renewable Energy Agency - IRENA … Nov 2019
  6. 6. Analysis of flexibility needs 6ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM overall system perspective (maintain stable frequency and secure energy supply) local perspective (maintain bus voltages and secure transfer capacities) Flexibility needs are considered for both operation and planning of the power system, with flexibility support required in the timescales of: Flexibility needs have to be considered from: minutes / hours e.g. thermal loadings and generation dispatch fraction of a second e.g. stability and frequency support months / years e.g. planning for seasonal adequacy and planning of new investments Nov 2019
  7. 7. Flexibility needs and resources 7ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM Flexibility may be found in the whole power system Needs for flexibility are not limited to the balance of supply and demand … needs also refer to maintaining of voltages and securing transfer capacities Flexibility Solutions are not limited to modification in supply and demand • many different type of solutions may provide value to increase the flexibility • including solutions to influence rules and regulations in operation and planning Flexibility resources include: Energy storageSector coupling Synchronous conventional power plants Power electronic interfaced renewable power plants Demand Operational and planning proceduresGrid infrastructure primary/secondary equipment Nov 2019
  8. 8. Categorization of flexibility needs 8ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM Flexibility for Transfer Capacity Flexibility for Energy Flexibility for Power Flexibility for Voltage Nov 2019
  9. 9. Flexibility for: Power ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 9 Need description: Main rationale: Increased amount of intermittent, weather dependent, power supply in the generation mix Activation timescale: fractions of a second up to an hour Short term equilibrium between power supply and power demand, a system wide requirement for maintaining the frequency stability • upward and downward balancing capability of RES • aggregated control of supply and demand • short-term storage units Nov 2019 Example of flexibility solutions • interaction between multi-energy carrier systems • Increase operational limits of frequency deviations
  10. 10. Flexibility for: Power ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 10 Power Electronic Interfaced Generation (PEIG) impact on frequency event Source: NORDIC TSOs PV impact on other production units Source: California ISO Net load (MW) Nov 2019
  11. 11. Flexibility for: Energy ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 11 Need description: Medium to long term equilibrium between energy supply and energy demand, a system wide requirement for demand scenarios over time Main rationale: Decreased amount of fuel storage-based energy supply in the generation mix Activation timescale: hours to several years • optimisation of the value of stored energy • pumped hydro power plants • increased interconnections between systems • altering demand behaviour to follow variations in supply Nov 2019 Example of flexibility solutions
  12. 12. Flexibility for: Energy ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 12 Reservoir energy content Norway Source: NVE Irelands power system average generation mix April 2019 Source: EirGrid Coal: 0.6% Gas: 58,4% Net import: 0.7% Other 10.5% Renewables: 30% 20 year - Max 20 year - Mean 20 year - Min 70 40 10 13 261 39 Week Stored Energy (TWh) Nov 2019
  13. 13. Flexibility for: Transfer Capacity ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 13 Need description: Short to medium term ability to transfer power between supply and demand, where local or regional limitations may cause bottlenecks resulting in congestion costs Main rationale: Increased utilization levels, with increased peak demands and increased peak supply Activation timescale: minutes to several hours • Topology changes • Increasing nominal voltage levels • Time variable transfer tariffs to influence behaviour • Dynamic rating of overhead lines and other equipment • Risk based operation/planning criteria (instead of N-1) Nov 2019 Example of flexibility solutions
  14. 14. Flexibility for: Transfer Capacity ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 14 Percentage of population in Urban areas Source: UN PV production Germany 1st week July 2018 Source: Fraunhofer Nov 2019
  15. 15. Flexibility for Voltage ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 15 Need description: Short term ability to keep the bus voltages within predefined limits, a local and regional requirement Main rationale: Increased amount of distributed power generation in the distribution systems, resulting in bi-directional power flows and increased variance of operating scenarios Activation timescale: seconds to tens of minutes • Voltage boosters• Voltage support from distributed generation, storage and demand • Broadening of acceptable ranges for power quality Nov 2019 Example of flexibility solutions • Coordinated voltage control • Flexible AC Transmission Systems (FACTS)
  16. 16. Flexibility for Voltage ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 16 Distribution transformer net load in system with PV (positive=overproduction) Source: RISE 7:00 13:0010:00 19:0016:00 Nov 2019
  17. 17. Flexibility providers ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 17 System wide Transmission Distribution Local Flexibility for Transfer Capacity Flexibility for Energy Flexibility for Voltage Flexibility for Transfer Capacity Flexibility for Energy Flexibility for Power Flexibility for Voltage Power System Stabiliser Flexible AC Transmission System On-Load Tap-Changer Fast Frequency Response Automatic Voltage Regulator Battery Energy Storage local HVDC Super grid Battery Energy Storage short term Rescheduling Demand Side Response Optimisation Demand Side Response Coordinated Voltage control Topology changes Energy storage Long term Virtual Inertia Voltage boosters Phase-Shifting Transformer Back-up generation Examples of flexibility solutions involving: System services, Control-based responses, Operational procedures, and Implementation of new power components resources can be used for more than one category resources can be used for more than one category Nov 2019
  18. 18. Flexibility needs in time and space 18ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM Subsecond Second Minute Hour Day Years Regional& Locallevel System level Flexibility for Voltage Flexibility for Transfer Capacity Flexibility for EnergyFlexibility for Power Nov 2019
  19. 19. Power system flexibility: the ability of the power system to manage changes Summary / Conclusion ISGAN, ANNEX 6 - FLEXIBILITY NEEDS IN THE FUTURE POWER SYSTEM 19 Power system flexibility: the ability of the power system to manage changes … a broad concept! Flexibility for Transfer Capacity Flexibility for EnergyFlexibility for Power Flexibility for Voltage Thus, it is highly recommended to explain which kind of flexibility that is in question. This work proposes the categorization of flexibility into four needs: For further reading, download the full report: iea-isgan.org/flexibility-in-future-power-systems Nov 2019
  20. 20. Thank you Emil Hillberg Technical Lead ISGAN Annex 6 Researcher RISE Research Institutes of Sweden Emil.Hillberg@ri.se

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