Techno-economic Analysis of Reactive Power Provision in Decentralizing Energy Systems. Fabian Hinz.

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1 Faculty of Business and Economics, Chair of Energy Economics, Prof. Dr. Möst Techno-economic Analysis of Reactive Power Provision in Decentralizing Energy Systems Fabian Hinz 40th IAEE International Conference Singapore, June 2017

2 Introduction Model development Scenario generation Economics of voltage stability Conclusions TU Dresden, Chair of Energy Economics, Fabian Hinz 2 / 19

3 Reactive power flows originate from a shift between voltage and current Reactive power required AC voltage and current phases, real and reactive power Voltage / current diagram φ=0 φ=30 φ=60 φ=90 Pointer diagram P 0 30 capacitive inductive Q p t = u(t) i(t) P real power W Q reactive power var S apparent power VA Power flows Partly Strongly Purely inductive ohmic load load load Merely Large Small Only reactive real real power power flow, flow large small reactive power flow Power Small Large All power amounts flows flows in one of back power direction. and flows forth. back and forth. By electricity consumers By grid components To adjust operating voltage TU Dresden, Chair of Energy Economics, Fabian Hinz 3 / 19

4 Reactive power influenced cost increases in recent years Ancillary services and cost development in Germany from 2005 to 2015, in mio. EUR 1, Affected by reactive power Purpose 1, , Transmission losses 1) Compensate transmission losses 1, , Congestion mgmt. 8 Ensure technical feasibility of dispatch 1, Voltage control 1,119 1, Maintain admissible voltage band , Supply re-establishment Recover system from a blackout 1, , Frequency control Balance supply and demand 5 Input Real power Redispatch Reactive power Black start capability Reserve power Reactive power influence Reactive power transfers cause transmission losses Increase of reactive power feed-in through voltage-induced redispatch Direct provision of reactive power by conventional power plants Source: Bundesnetzagentur ) Generally not considered an ancillary service, but an operator expenditure influenced by reactive power TU Dresden, Chair of Energy Economics, Fabian Hinz 4 / 19

5 Reactive power from the distribution grid is required in the future Reactive power supply: conventional and future scenario Transmission grid Conventional supply Future supply React. power consumption Inductive under load Capacitive when idle 110 kv grid Inductive under load Capacitive when idle Medium / low voltage grid Reactive power consumption Reactive power consumption Capacitive due to cables Electricity feed-in Germany 62% 38% % 13% 42% 28% 51% 59% Reactive power supply Conventional supply through large power plants Availability in the transmission grid decreases Supply can be replaced by RES in the distribution grid Source: Kraftwerksliste BNetA 2015, Netzentwicklungsplan 2025 Controllable reactive power Offshore TSO DSO TU Dresden, Chair of Energy Economics, Fabian Hinz 5 / 19

6 Research Question How can voltage stability be efficiently achieved in a decentralizing electricity system? TU Dresden, Chair of Energy Economics, Fabian Hinz 6 / 19

7 Introduction Model development Scenario generation Economics of voltage stability Conclusions TU Dresden, Chair of Energy Economics, Fabian Hinz 7 / 19

8 ELMOD LinAC linearizes grid balance equations of ELMOD AC Grid balance Simplified model formulation of ELMOD AC and ELMOD LinAC Target function: Min n N cost n marg Genn P Thermal limit: Voltage range TS: Voltage range DS: Generator curve: LineCurrent l Thermallimit l 0, 97 p. u. U n 1, 03 p. u. 0, 94 p. u. U n 1, 06 p. u. Gen P n, Q Gen n Gen P Gen Q ELMOD LinAC Real power: Gen n P Dem n P Loss n P = m N g n,m U n U m Reactive power: Gen Q n Dem Q Q n Loss n = m N b n,m U n U m Iterative calculation ELMOD AC Real power: Gen P n DemP n = U n U m g n,m cos(θ n θ m ) m N Reactive power: Non-linearities Gen Q Q n Dem n = U n U m g n,m sin(θ n θ m ) m N 1) U n / U m... Voltage magnitude at node n / m Θ n / Θ m... Voltage angle at node n / m g n,m / b n,m... Conductance / susceptance between node n and m Nodal 110 kv potentials TU Dresden, Chair of Energy Economics, Fabian Hinz 8 / 19

9 Wind feed-in 24 representative grid situations generated Generation of representative grid situations, frequencies and values Clustered grid situations Germany 2014 Representative grid situations Vertical load 1) freq. F L M H V Few 0,1% 0,2% 1,3% 0,4% 0,1% Low 0,7% 5,1% 12,4% 4,3% 0,5% Med 0,9% 13,5% 24,3% 10,6% 0,7% High 0,3% 3,8% 11,1% 7,0% 0,8% Vast - 0,4% 0,9% 0,7% 0,1% GW 33,4 43,5 54,0 66,7 75,2 LF 0,5% 3,1% 12,6% 36,0% 70,9% Approach Data set for 8760h categorized in 5 categories by Wind feed-in (availability of RES reactive power) Residual load (demand for reactive power) 24 representative situations associated with respective frequencies 1) Vertical load defined as load MINUS PV feed-in TU Dresden, Chair of Energy Economics, Fabian Hinz 9 / 19

10 Introduction Model development Scenario generation Economics of voltage stability Conclusions TU Dresden, Chair of Energy Economics, Fabian Hinz 10 / 19

11 Six different electricity system scenarios defined Scenarios: Electricity system Electricity system scenarios Status Quo Historic data from 2014 Grid status quo Full grid Planned grid extension from NEP 2025 Scenario 2025 B 3 HVDC corridors, 6 systems (DC5/6I Wolmirstedt Isar with 2 circuits) Delayed grid 5 year delay for onshore AC and DC grid extensions 0.5 HVDC corridors, 1 system (DC2, Osterath Phillipsburg) Full grid Delayed grid Green Planned grid extensions from NEP 2014 Scenario 2034 B 3 additional HVDC systems in the West of Germany 5 year delay for onshore AC and DC grid extensions Only 3 HVDC corridors, 6 systems Extreme scenario: Delayed grid extensions AND Lignite phase-out TU Dresden, Chair of Energy Economics, Fabian Hinz 11 / 19

12 Increasing reactive power ranges resulting from RES involvement Scenario: RES Distribution system Renewables [Mvar] Min Avg Max Range [Mvar] Min Avg Max Range [Mvar] Min Avg Max Range Increasing reactive power potentials in future scenarios Certain reactive power potentials also in low wind situations TU Dresden, Chair of Energy Economics, Fabian Hinz 12 / 19

13 Introduction Model development Scenario generation Economics of voltage stability Conclusions TU Dresden, Chair of Energy Economics, Fabian Hinz 13 / 19

14 Results Availability and usage of reactive power depends on grid situation Scenario: RES SQ14 Distribution system Renewables, 110 kv usage Low wind, low load Used potential capacitive Legend Used potential inductive High wind, high load Unused potential capacitive Unused potential inductive Size of circles proportional to control range Small potentials from 110 kv grid (conv. plants) Potential inductive due to inductive MV behavior Usage of capacitive potential due to idle grid Large potentials from 110 kv grid Potential mostly capacitive due to inductive load Usage of inductive potential due to loaded grid TU Dresden, Chair of Energy Economics, Fabian Hinz 14 / 19

15 Results Grid extension delays lead to increased saving potentials through additional reactive power [mio. EUR] Scenario comparison Germany 2014/2025/2035, in mio. EUR SQ14 Full25 Delay25 Full35 Delay35 Green ,8-4,4-2,9-0,2-9,3 Status Quo ,9-3,3-1,9-5,6-14,8 Full grid extension -3,5-2,2-5,6-19,9-31,2 Delayed grid extension ,7-4,5-2,9-2,6-10,6-8,6-26,8 Full grid extension -15,1-14,0-36,3 Delayed grid extension -4,9-6,2-12,8-16,4-40,3 Green - no lignite Certain cost saving potential already in the status quo Savings potential mainly from loss reductions Increasing savings potential in delayed grid scenario Large savings in redispatch Significance of reactive power concept increases with delays in grid extension Higher saving potential when grid extension is delayed, especially in combination with lignite phase-out Savings in redispatch and curtailment Losses DS Losses TS Curtailment Redispatch TU Dresden, Chair of Energy Economics, Fabian Hinz 15 / 19

16 High savings potential in situations with a low residual load Comparison of reactive power and savings potential per grid situation Reactive power potential Cost savings potential Highest potential between 20% and 40% wind feed-in Potential around 0% wind feed-in results from conventional power plants in the 110 kv grid Above 50% wind feed-in reduced potential due to congestions and reaching of voltage limits Moderate savings potential in areas of low and medium wind feed-in as well as medium and high load Largest savings potential at high wind feed-in and low load Due to low residual load, only a few conventional power plants are dispatched Wind turbines provide a sufficient reactive power potential Which situations lead to a high need for reactive power from the distribution grid? TU Dresden, Chair of Energy Economics, Fabian Hinz 16 / 19

17 Only a small share of potential reactive power sources has to be made available Reactive power control range [Gvar] System cost reduction [mio. EUR p.a.] Reactive power control ranges and cost savings under different shares of wind power inclusion Capacitive Inductive % 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Increasing share of wind power plants with reactive power control Aggregated control range in Germany 2025 increases slightly less than proportional % 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Share of wind power plants with reactive power control 7.8 How many reactive power sources have to be made available? System cost reductions show limited growth 72% of cost reductions achieved with a 20% share of wind power plants TU Dresden, Chair of Energy Economics, Fabian Hinz 17 / 19

18 Introduction Model development Scenario generation Economics of voltage stability Conclusions TU Dresden, Chair of Energy Economics, Fabian Hinz 18 / 19

19 Conclusions Methodology Suitable techno-economic models developed that allow reactive power analysis of large-scale systems Reactive and conventional power plants in the 110 kv grids are able to influence reactive power exchange with the transmission grid Economic implications Reactive power required in low residual load situations Reactive power supply from 110 kv RES and conventional plants leads to a cost reduction potential between 9 and 40 mio. EUR Only 20% of 110 kv reactive power sources required to achieve substantial savings Delayed grid extension or lignite phase-out make local supply of reactive power more important TU Dresden, Chair of Energy Economics, Fabian Hinz 19 / 19

20 Faculty of Business and Economics, Chair of Energy Economics, Prof. Dr. Möst Thank you for your attention! Dipl. Wi.-Ing. Fabian Hinz Chair of Energy Economics Faculty of Business and Economics TU Dresden Phone: