Outline • Background & Motivation • Reserve Modeling Framework • Types of improvements • COMPETES simulations • Results
Challenges Arising from Wind Quack! Source: Flexibility in 21st Century Power Systems, NREL Report Source: CAISO
Reserve ve is extra capacity (MW) needed • Opera rating Re Reserve in case of contingency Loss of a generator • • Loss of a transmission line • Sudden change in load • Now : change in renewable energy Frequency restoration (mFRR), not automatic frequency response 120 100 MW 80 Expected Demand 60 Reserve+Expected Demand 40 1 6 11 16 21 Hour
Operational Reserve 1. Size / Procure • How much do we need? • E.g., extra 30 MW on-line in every hour 2. Allocate • Who will be scheduled? Generator B & C will each provide 15 • MW 3. Activate Who will provide the energy if actually • needed? • Deliverability in real time market
Procurement How much do we need? • • Often called ’reserve requirement’ Examples • • Capacity of largest generator or transmission line • X % of demand and Y % of renewables for … • One day • One season 120 100 80 MW 60 Expected Demand Reserve Ex % 40 Reserve Ex Fixed 20 Hour 1 6 11 16 21
Allocation Who will be scheduled? • Most US markets • Most European markets • Market based • Long-term contracts • Primary • Portfolio based • Secondary • Unit based • Tertiary • Some dispatch • Determined in zones • Determined by country Source: ENTSO-E
Activation Who will actually provide reserves if needed? • • Generators change energy output level in balancing • Contract-based • TSO can call on contracted generators to provide reserve in real time • Market-based (US) • System operator calls on generators selected in the day-ahead for reserve • Energy must be deliverable • Transmission constraints might limit deliverability within and between countries
ECN-JHU Current Research Question What changes to market design will most enhance efficiency in procuring/allocating/activating reserve?
Types of Improvements • Reserve r requirement p procurement p period o Seasonal § Current practice, four seasonal periods assessed o Enhancement : Daily § Requirement determined daily Example requirement: • Allocation t type 3% of demand and 5% of renewable generation o Contract-based § Current practice § Bi-lateral contracts between TSO and generators o Enhancement: Market-based § Procured through co-optimization with energy market • Amount o of c coordination o Independently determined, current practice o Enhancement: Northwest Europe coordinates
Efficiency of Reserve Reserve R Requirement • Each axis shows Daily a different improvement to reserve • Increasing complexity and efficiency Seasonal moving away from origin DA & Balancing No Coordination Co Coordinati tion • Star = hypothetical ideal • Dot = worst case Increasing complexity, efficiency à Thanks to Qingyu Xu
COMPETES Network 33 node pan-European network • • Transmission mimics integrated EU network with capacity limited by NTC • Future generation + potential energy storage • Renewable scenario based on ENSTO-E 2030 Vision 4 of “European Green Revolution”
Model Formulation: Unit Commitment • Min Operating Cost • Subject to • Generator min & max capacity • Ramp limits • Min up & down times • Transmission line capacity & flow (Net Transfer Capacity) • Startup & no-load binary constraints / relaxed formulation
Operational Markets • Day Ahead • Schedules generation for the following day • Inputs: bids & offers, forecast for load and wind , reserve sizing • Outputs: prices, schedule (on/off), dispatch • à Reserve allocation phase • Balancing • Updates schedule to reflect new information • Inputs: new bids & offers, updated forecast • Outputs: prices, fast start schedule, dispatch • à Reserve activation phase • Was the right amount procured? • Was it allocated to those who could deliver it?
Simulations & Sensitivity Analysis Day-Ahead • Simulations • Simulated one day-ahead forecast Bal. 1 Bal. 3 Bal. 5 • Followed by 5 real-time ”actual” wind realizations Bal. 2 Bal. 4 • Results show mean of 5 simulations • Error bars show minimum and maximum deviations • Added an extra coordination component • Due to results found by K. van den Bergh in [4], we consider coordination in balancing alone with no coordination in day-ahead K. van den Bergh, [4]
Efficiency of Reserve Requirement • Each axis shows Daily a different improvement to reserve Reserve R • Increasing complexity and efficiency Seasonal Coordinati Co tion moving away from origin • Star = hypothetical ideal • Dot = worst case
Operating Costs • Example results comparing • Star, ‘ideal case’ (DMC) -0.29 0.32 0% EU • Reserve size based on daily average • Market-based allocation • Co Coordinati tion in d day-ahead a and b balancing NL 0% • Rectangle (DMN) • Reserve size based on daily average • Market-based allocation 54.9% = DMN op costs − DMC op cost • No c coordination DMC op cost 55.6 54.0 +54.9% Daily Requirement 54.9%: 20% load shedding +59.3% Reserve R 80% Deviation of Deviation of generation maximum minimum Seasonal deviations Co Coordinati tion scenario scenario
Results – operating cost % deviations from ‘ideal’ case without load shedding 34.3 37.9 -0.20 -0.66 0.91 0.95 0% +0.28% +35.7% +0.05% 0% +40.9% Daily 0.37 -0.30 0.44 39.9 41.7 -0.33 Requirement NL Reserve R EU 27.7 -0.48 -0.72 31.4 2.50 1.62 +29.1% +0.67% -0.04% +0.12% +32.1% +0.11% Seasonal 33.0 30.9 -0.21 0.51 -0.23 0.49 Co Coordinati tion
Lowest Cost Solution by Country Where is each country is better off? CZE, DEW, FRA, GER, DEN, POL, - UKI ITA, Daily POR, Requirement SKO, SPA, SWE, SWI, Reserve R NOR, BLK BEL, FIN, - NED, BLT Seasonal IRE Co Coordinati tion
Results – wind curtailed % deviations from ‘ideal’ case, NL data in MWh 448 8350 0 MWh 0 MWh 3875 MWh -2.7% 0% +6.6% Daily 13 -7.7 10 1.7 20 -4.8 Requirement NL Reserve R EU 448 8350 3885 MWh 0 MWh 0 MWh -3.5% +6.2% -0.6% Seasonal 19 1.1 -8.2 9.1 -5.3 11.4 Co Coordinati tion
Reserves: Source Fuel All market based simulations showed similar percentages Gas 37% Storage prod. Nuclear 59% 0% Wind Sun 0% 0% Oil Res-e 0% Coal Lignite 1% 2% 1%
Contracted Reserve Cases • All contracted cases Reserve R Requirement showed higher c costs o Some cases were Daily double the cost of the market-based cases § Some countries faced significant load shedding § Wide difference in +40.9% 0% operating costs country by country Seasonal +30.0% • Fewer MWh of wi wind d +110% curtailment than ‘ideal’ cu Balancing No Coordination Co Coordinati tion case when reserves were coordinated in balancing o Additional plants online meant lower curtailment +32.1% +0.17%
Conclusions Three Suggested Other Observations Improvements: Ø More coordination may 1. Difference between daily vs. seasonal requirement is lead to more wind minimal curtailment 2. Coordination in balancing • Possibly due to location of achieves almost all benefit, reserve within country or can produce better • Consideration of forecast solution uncertainty and wind farm 3. Naïve contracts for reserves location can reduce produce least efficient curtailment solution compared to Ø Storage can provide a market significant amount of • Coordination in reserve reserve allocation & balancing might make up for higher costs
References [1] S. Kasina, S. Wogrin, and B.F. Hobbs, “A comparison of unit commitment approximations for generation production costing,” Working Paper, Johns Hopkins University, 2014. [2] Ö. Özdemir, F. Munoz, J. Ho, and B.F. Hobbs, “Economic Analysis of Transmission with Demand Response and Quadratic Losses by Successive LP,” IEEE Trans. Power Syst. , DOI: 10.1109/TPWRS.2015.2427799, in press. [3] J. Cochran, M. Miller, O. Zinaman, M. Milligan, D. Arent, B. Palmintier, M. O’Malley, S. Mueller, E. Lannoye, A. Tuohy, B. Kujala, M. Sommer, H. Holttinen, J. Kiviluoma, and S. K. Soonee, “Flexibility in 21st Century Power Systems,” Golden, CO, 2014. [4] K. van den Bergh, R. B. Hytowitz, K. Bruninx, E. Delarue, W. D'haeseleer, and B.F. Hobbs, "Benefits of coordinating sizing, allocation and activation of reserves among market zones," Electric Power Systems Research , 143: 140–148, Feb. 2017.
Thank you! Questions? Email: hytowitz@jhu.edu
Backup slides
Results – operating cost % deviations from ‘ideal’ case 58.0 61.5 -0.34 -0.66 0.77 0.95 0% +0.14% +59.3% +0.04% 0% +54.9% Daily 0.32 -0.26 0.39 54.0 55.6 -0.29 Requirement NL Reserve R EU 57.4 -0.28 -0.74 61.1 2.69 1.60 +58.8% +0.87% -0.05% +0.14% +55.4% +0.17% Seasonal 56.1 54.3 -0.06 0.37 -0.08 0.36 Co Coordinati tion
Requirement Generation Mix Daily Reserve R TWhdifference between Seasonal (Seasonal/Market/No Coordination) -(Daily/Market/Coordination ) Co Coordinati tion More in S/M/NC case → ← More in ‘ideal case’
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