Application of Battery Energy Storage for Frequency Regulation Alexandre Oudalov IEEE PES Swiss Chapter Workshop, Daettwil, 9.11.2006
Agenda Energy storage technologies and applications Primary frequency control and ancillary service markets Dimensioning of the BESS for primary frequency control Conclusions Q&A ABB Switzerland Ltd, Corporate Research - 2
Energy storage technologies Excessive electricity is stored at times of low demand, then the energy is retrieved when demand peaks ABB Switzerland Ltd, Corporate Research - 3 Low demand Power System electric energy production and consumption Energy Storage Electrochemical Electrical Mechanical Thermal
Energy storage technologies Excessive electricity is stored at times of low demand, then the energy is retrieved when demand peaks Energy Storage ABB Switzerland Ltd, Corporate Research - 4 Power System electric energy production and consumption Peak demand Electrochemical Electrical Mechanical Thermal
Energy storage technologies Excessive electricity is stored at times of low demand, then the energy is retrieved when demand peaks Energy Storage ABB Switzerland Ltd, Corporate Research - 5 Power System electric energy production and consumption Electrochemical Electrical Mechanical Thermal
Energy storage technologies Excessive electricity is stored at times of low demand, then the energy is retrieved when demand peaks ABB Switzerland Ltd, Corporate Research - 6 Pumped-Hydro Storage (PHS) Battery Energy Storage Systems (BESS): Lead Acid Nickel-Cadmium Nickel-Metalhydride: too expensive Sodium-Sulfur Lithium-Ion: too expensive Vanadium Redox flow Polysulfide-bromine flow (project stopped) Superconducting Magnetic Energy Storage: too expensive Electrochemical Capacitors: too expensive Flywheels: too expensive Hydrogen technology: not yet mature Thermo electric energy storage: not yet mature Compressed Air Energy Storage: needs fuel, site dependent
Applications of BESS in power systems Central generation BESS Load leveling for generation utilization 10-100 MW, 1-4h Load leveling for postponement of grid upgrade 10-100 MW, 1-4 h BESS T 220 kv Overhead line to Load 20 kv 220 kv Frequency control 1-20 MW, 0.5-2 h BESS Industry ABB Switzerland Ltd, Corporate Research - 7 Distributed generation BESS 20 kv 110 kv Integration of renewables 1-100 MW, 1-10 h Weak connection 110 kv 20 kv Network ring BESS Peak shaving 0.1-10 MW, 1-2 h
Applications of BESS in power systems Will a BESS for that specific application alone be a profitable solution? Primary Frequency Regulation in the today s market Integration of renewables (in island grid) Applications Load leveling for postponement of T&D upgrade End-user Peak shaving ABB Switzerland Ltd, Corporate Research - 8 out of question Load leveling for generation utilization (large scale arbitrage) not profitable in a few, very special cases only might be profitable probably profitable
BESS for frequency control - Roadmap CHINO Lead-Acid, USA TEPCO NaS, Japan AEP NaS, USA 1986 1988 1994 1998 2001 2003 2006 ABB Switzerland Ltd, Corporate Research - 9 BEWAG Lead-Acid, Germany PREPA Lead-Acid, Puerto Rico GVEA Ni-Cd, USA
BESS in Golden Valley Electric Association In operation since 2003 System Supplier: ABB in cooperation with SAFT (Ni-Cd battery cells) Cost: 35 million US$ Specification: ABB Switzerland Ltd, Corporate Research - 10 Ni-Cd Batteries Converter 40 MW for 7 min (4.7 MWh) 27 MW for 15 min (6.75 MWh) AC to AC efficiency 75% Applications: Backup power in case of line loss Reactive power support
BESS in Golden Valley Electric Association Existing 100 MW Transmission line Fairbanks In operation since 2003 System Supplier: Northern Intertie 140 MW BESS ABB in cooperation with SAFT (Ni-Cd battery cells) Cost: 35 million US$ Specification: ABB Switzerland Ltd, Corporate Research - 11 Healy Ni-Cd Batteries Converter 40 MW for 7 min (4.7 MWh) 27 MW for 15 min (6.75 MWh) AC to AC efficiency 75% Applications: Backup power in case of line loss Reactive power support
Frequency control reserves operating dead-band ABB Switzerland Ltd, Corporate Research - 12
BESS operating principle for frequency control in f f t INJECT POWER ABSORB POWER P ABB Switzerland Ltd, Corporate Research - 13 BESS Power System out
ABB Switzerland Ltd, Corporate Research - 14 Primary frequency control market mechanism Forecasted need Frequency primary reserve required (MW) 60 50 40 30 Bidding process per kw 20 60 70 60 70 60 50 40 30 20 70 60 50 40 30 20 Period 1 Period 2 Period 3 BESS Tendering period: Germany Czech Rep. 6 months 1 week New Zealand 1 day
Cost of primary control reserve in Germany ABB Switzerland Ltd, Corporate Research - 15 Source: http://www.eon-netz.com/ http://www.vattenfall.de/ http://www.rwe-transportnetzstrom.com/ http://www.enbw.com
UCTE measured frequency April 2005 50.2 50.15 50.1 50.05 50 49.95 49.9 49.85 49.8 5 10 15 20 25 30 2005 ETRANS ABB Switzerland Ltd, Corporate Research - 16 Measured frequency [Hz] Time [Day]
Frequency statistics April 2005 50 45 ABB Switzerland Ltd, Corporate Research - 17 Relative time period [%] Relative time period [%] 40 35 30 25 20 15 10 5 67.4% } 35.6% 31.8% 16.1% 15.2% 0.5% 0.8% 0 <-0.2 -.2 - -.14 -.14 - -.1 -.1 - -.06 -.06 - -.02 -.02-0 0 -.02.02 -.06.06 -.1.1 -.14.14 -.2 >.2 Frequency deviations (intervals) [Hz] Frequency deviation intervals [ Hz ]
Regulation characteristic 1.5 1 0.5 0 20-300 -200-100 0 100 200 300-0.5-1 -1.5 Frequency deviation from 50Hz [mhz] Battery charge Battery discharge ABB Switzerland Ltd, Corporate Research - 18 Primary reserve activation [p.u.]
BESS primary control power April 2005 0.5 0.4 0.3 ABB Switzerland Ltd, Corporate Research - 19 BESS Power [Pn] 0.2 0.1 0-0.1-0.2-0.3-0.4-0.5 5 10 15 20 25 30 Time [Day] Battery charge Battery discharge
BESS efficiency 0.7 with no recharge April 2005 0-0.2-0.4-0.6-0.8-1 -1.2-1.4-1.6 5 10 15 20 25 30 Time [d] ABB Switzerland Ltd, Corporate Research - 20 Absolute depths of discharge [ Pn x h ] State of Discharge [Pn*h] Time [ day ] Minimum Battery Capacity = 1.62 P n *h
Assumption for modeling Frequency deviation can not be predicted! BESS =! 100% availability Battery should never be empty! (try to keep battery charged using a small recharge power when f < 20mHz ) For any case keep an additional reserve capacity of 15min x P n In case battery is full, absorb power with resistors ABB Switzerland Ltd, Corporate Research - 21 BESS = Battery (P n, P n *h) + Resistors (P R = P n )
BESS efficiency 0.7 recharge with 1% of P n 0.1 0-0.1-0.2-0.3-0.4-0.5-0.6-0.7-0.8 5 10 15 20 25 30 Minimum Battery Capacity = 0.71 P n *h ABB Switzerland Ltd, Corporate Research - 22 Absolute depths of discharge [ Pn x h ] State of Discharge [Pn*h] April 2005 Time [d] Time [ day ]
BESS efficiency 0.7 recharge with 1% of P n 0.6 0.5 0 0.4 0.3 0.2 0.1 0-0.1-0.2-0.3-0.4-0.5 5 10 15 20 25 30 Time [d] ABB Switzerland Ltd, Corporate Research - 23 BESS power [ Pn ] Power: pure Battery power (red) and resistor (blue)[pn] -0.6 April 2005 Time [ day ] Energy loss in resistors = 2.74 P n *h
BESS efficiency 0.7 recharge with 3% of P n 0.1 0-0.1-0.2-0.3-0.4-0.5 5 10 15 20 25 30 Time [d] ABB Switzerland Ltd, Corporate Research - 24 Absolute depths State of Discharge discharge [Pn*h] [ Pn x h ] April 2005 Time [ day ] Minimum Battery Capacity = 0.26 Pn*h
BESS efficiency 0.7 recharge with 3% of P n 0.6 0.5 0 0.4 0.3 0.2 0.1 0-0.1-0.2-0.3-0.4-0.5 5 10 15 20 25 30 Time [d] ABB Switzerland Ltd, Corporate Research - 25 BESS power [ Pn ] Power: pure Battery power (red) and resistor (blue)[pn] -0.6 April 2005 Time [ day ] Energy loss in resistors = 6.69 Pn*h
BESS efficiency 0.7 recharge with 0-5% of P n 0-0.2-0.4-0.6-0.8-1 -1.2-1.4-1.6 5 10 15 20 25 30 Time [d] ABB Switzerland Ltd, Corporate Research - 26 Absolute depths of discharge [ Pn x h ] State of Discharge [Pn*h] April 2005 Time [ day ] 5% 3% 1% No recharge
Assumptions for modeling Absorb positive peaks by charging battery, as long as battery is not full Provide negative peaks by discharging battery Define range of preferred state of charge with an upper and lower level ABB Switzerland Ltd, Corporate Research - 27 In case 0 battery state of charge exceeds pre-defined upper level Depths of discharge [ P n x h ] Sell small portion of the stored energy (ex. 0.02*P n for 1h) in order Upper to level bring -0.1 back state of charge to preferred operating range Lower level State of Discharge [Pn*h] -0.2 In case battery state of charge falls below pre-defined lower level -0.3 Recharge battery to the pre-defined state of charge lower level when f -0.4 < 20mHz Use minimal recharge power (ex. 3% of P n ) -0.5?? -0.6 What is the optimal capacity and what are the optimal upper and lower state of charge levels 5 10 15 20 25 30 Time [d] Time [ day ]
Objective: maximized NPV of profit ABB Switzerland Ltd, Corporate Research - 28 Input Max. Power (contracted primary reserve) Frequency profile Regulation characteristic BESS efficiency, life cycle and cost function Recharge tariff and Sell power tariff (intraday market) Reserve price Variables Upper and lower state of charge level Recharge power % of Pn Sell power % of Pn Output Required capacity Volume of sold and recharged energy Sell Power [% P n ] Volume of lost energy through resistors Max(NPVprofit = NPVrevenue NPVcost) 0.12 0.76 0.1 0.661 0.646 0.631 0.08 0.691 0.684 0.676 0.669 0.616 0.699 0.06 0.601 0.04 0.571 0.586 0.654 0.609 0.639 0.02 0.624 0.594 0.556 0.579 0.564 0 0.55 0 0.02 0.04 0.06 0.08 0.1 0.12 SoC upper level [ P n *h ]
Battery state of charge April 2005 0.1 0-0.1-0.2-0.3-0.4-0.5-0.6 5 10 15 20 25 30 Sell power 0.03 P n Recharge power 0.03 P n ABB Switzerland Ltd, Corporate Research - 29 Depths of discharge [ Pn x h ] State of Discharge [Pn*h] Time [d] Time [ day ] 100% 92% 73% 52% State of charge Required Capacity: 0.62 P n x h 35% 19% 0% SoC max SoC min
Primary reserve power curve April 2005 1 0.8 0.6 0.4 0.2 0-0.2-0.4-0.6-0.8-1 -0.2 5 10 15 20 25 30 ABB Switzerland Ltd, Corporate Research - 30 BESS power [ Pn ] Power: pure Battery power (red) and resistor (blue)[pn] Time [d] Time [ day ] BESS power (contracted reserve) 2 MW Recharged energy 8.2 MWh Sold energy 3 MWh Energy absorbed by resistors 1.6 MWh 0.5 0.4 0.3 0.2 0.1 0-0.1-0.3-0.4 Power: pure Battery power (red) and resistor (blue)[pn] -0.5 5 10 15 20 25 30 Time [d]
0.5 0.4 0.3 0.2 0.1 0-0.1-0.2-0.3-0.4 Absorbed by resistor Sold energy Bought energy -0.5 0 50.1 18.8 19 19.2 19.4 19.6 19.8 Time [d] 18.8 19 19.2 19.4 19.6 19.8 ABB Switzerland Ltd, Corporate Research - 31 Depths of discharge Frequency [ Pn x [ h Hz ] ] BESS power [ Pn ] Supplied by battery Power: pure Battery power (red) and resistor (blue)[pn] -0.05 50.05-0.1 50-0.15 49.95-0.2 49.9 Time [ day ] 100% State of charge Example: April 18-19, 2005 Absorbed by battery 92% 73% Measured frequency [Hz]
Multi-string BESS operation AS Market Energy Market ABB Switzerland Ltd, Corporate Research - 32
Space requirement for the 2 MW Lead-acid BESS BESS surface: 14.2 x 12.9 m (184m 2 ) Batteries building ABB Switzerland Ltd, Corporate Research - 33 MV OHL MV transformer PCS + control container
Summary BESS satisfy technical requirements for frequency regulation BESS can be a profitable solution for providing a primary reserve ABB is a supplier of large battery energy storage systems Modeling of a BESS Prototype construction and extended field tests Construction and commissioning of the system (ex. NiCd BESS Alaska) ABB Switzerland Ltd, Corporate Research - 34
ABB Switzerland Ltd, Corporate Research - 35 Thank you!
ABB Switzerland Ltd, Corporate Research - 36