Experience with primary reserve supplied from
energy storage system
Philip C. Kjaer, Vestas Wind Systems A/S
ATV: ”Energy storage – a must for successful conversion to green energy”
Monday 28th September 2015 – DTU, Lyngby, DK.
1
Content
• Motivation
• Application & Installation
• Test Results
• Conclusions & Perspectives
2
Vestas’ research programme on energy storage started in 2010:
Motivation: Identify value-add from wind power + energy storage.
Activities:
• Identify best match of applications (revenue) and ESS technology.
• Develop competence on optimal control w.r.t. ES life-time and ratings.
• Select & qualify suppliers.
• Verify life-time models.
• Demonstrate integration, functionality and economy.
Wind Power Plant with Energy Storage
Energy
Storage
Management
System
4 x 3MW
1.6MW x 0.25h
Lem Kær
substation & energy storage system
Forecast Error Reduction
Idea: Reduce financial penalties for not meeting generation commitment.
Reality: Aggregation of several wind plants over a geographical spread allows
similar gains.
Ramp Rate reduction / power smoothening (dP/dt control)
Idea: For power quality in weak networks, keep output variations from the
combined Wind/ESS plant below a threshold.
Reality: no payment for service; fast wear-out.
Cost: storage life-time
Modelling:
• Determine ESS ratings to warrant life-time for a given mission profile
• CAPEX (MW & MWh ratings + fixed cost)
• OPEX (efficiency + capacity degradation + standby + replacements + availability)
The most meaningful single number
expressing battery lifetime is the
allowed no. of charge/discharge
cycles of a given charge depth at a
certain temperature.
The potential services a Wind Power Plant augmented by
embedded Energy Storage can provide
Primary Reserve
• Ancillary services
•
•
•
•
•
•
•
•
•
•
•
NPV (%) relative to best case (GFR)
Primary Reserves
Secondary Reserves
Tertiary Reserves
Black Start
Load Shifting – Energy Arbitrage
Transmission Curtailment
Forecast Error Reduction
Ramp Rate reduction (dp/dt control)
Voltage Control
Islanding
(Transmission deferral)
Results from a 2009 Vestas study on a 66MW wind plant in three different locations (electricity markets).
Energy Storage installation
ESS1:
53’ container
0.4MW / 0.25h
LiFePO4
ESS2:
BMS
53’ container
Air-con
1.2MW / 0.25h
Fire suppression
ESS2:
Li4Ti5O12
Heat exchanger
Power electronic converter
BMS
Power electronic converter
Transformer 0.48/10kV
Air-con
Transformer 0.48/10kV
Heat exchangers
Fire suppression
10kV circuit breaker
Power System Stability
Source: NationalGrid, U.K.
Frequency support. Primary reserve.
The Danish TSO, Energinet.dk, defines the primary reserve product as:
•
“Regulation must be supplied at a frequency deviation of up to +/- 200 mHz relative to the reference
frequency of 50 Hz. This will normally mean in the 49.8-50.2 Hz range. A deadband of +/- 20 mHz is
permitted. The reserve must as a minimum be supplied linearly and be fully activated within 30 seconds
in the event of a frequency deviation of +/- 200 mHz.”
•
“……… be able to deliver a constant level of active power (dicharge) for 15 minutes. After another 15
minutes it should be able to repeat the delivery.”
- Auctions take place at 15h00 the day before delivery, and bids are supplied in 6 blocks of 4 hours each.
- Upwards and downwards regulation (under- and over-frequency, respectively) are separate, ie. asymmetrical
bids are permitted.
- For an ESS “up-regulation-only” provider, currently no requirements exist to the level and direction of the
power flow when not delivering upwards regulation.
Board of Directors
Bert Nordberg, Chairman
Born: 23 March 1956
Nationality: Swedish
Resident: Sweden
Position: President & CEO, Sony Mobile
Communications (Sweden)
Test
results
Jørn Ankær Thomsen
Born: 17 May 1945
Nationality: Danish
Resident: Denmark
Position: Attorney at Law and partner, Gorrissen
Federspiel (Denmark)
Lars Josefsson, Deputy Chairman
Born: 31 May 1953
Nationality: Swedish
Resident: Sweden
Position: Independent consultant
Kurt Anker Nielsen
Born: 8 August 1945
Nationality: Danish
Resident: Denmark
Position: Director
Carsten Bjerg
Born: 12 November 1959
Nationality: Danish
Resident: Denmark
Position: CEO and Group President of Grundfos
Management A/S (Denmark)
Knud Bjarne Hansen*
Born: 26 March 1952
Nationality: Danish
Resident. Denmark
Position: Senior Vice President, Vestas Wind
Systems A/S (Denmark)
Eija Pitkânen
Born: 23 April 1961
Nationality: Finnish
Resident: Finland
Position: Vice President, Head of Corporate
Responsibility, Telia Sonera (Sweden)
Kim Hvid Thomsen**
Born: 8 August 1963
Nationality: Danish
Resident. Denmark
Position: Industry technician and Senior Shop
Steward, Vestas Manufacturing A/S (Denmark)
Håkan Eriksson
Born: 8 April 1961
Nationality: Swedish
Resident: Australia
Position: Head of Ericsson Australia, New Zealand
and Fiji (Australia)
Michael Abildgaard Lisbjerg**
Born: 17 September 1974
Nationality: Danish
Resident: Denmark
Position: Skilled worker - Production & Shop
Steward, Vestas Manufacturing A/S (Denmark)
Jørgen Huno Rasmussen
Born: 25 June 1952
Nationality: Danish
Resident: Denmark
Position: President and CEO, FLSmidth & Co. A/S
(Denmark)
Sussie Dvinge Agerbo*
Born: 5 November 1970
Nationality: Danish
Resident: Denmark
Position: Management Assistant, Vestas Wind
Systems A/S (Denmark)
*) Elected by company employees
**) Elected by Group employees
Danish TSO
Primary Reserve approval test
>85% round-trip efficiency
15 minute activation
2000
1200
Discharge
1500
1.4MW
1000
1000
90% SoC
Power [kW]
Power [kW]
0
2700
2900
3100
3300
3500
3700
3900
4100
4300
4500
600
4700
-500
400
SoC1 [%]
State ofSoCCharge
[0/00]
800
500
P_Elspec_ESS1+ESS2+AUX
SOC 1
SOC 2
-1000
SoC2 [%]
200
Charge
-1500
10% SoC
-1.6MW
-2000
0
Time [sec]
0 min
15 min
30 min
Frequency recordings
6
7
Jan 1st 2013 – May 31st 2015
No samples vs. frequency (1 sec update)
x 10
6
Number of samples
5
4
3
2
1
0
49.8
49.85
49.9
‘Up-regulation’
49.95
50
50.05
Frequency
49.98 Hz
50.1
50.15
“Our recordings have shown that continuous
periods of 15 minutes of under-frequency
(below 49.98 Hz) only occur in average 50
times per month (ie. <2%).”
Charging controller
Data recorded at site
Frequency dev. [mHz]
Primary Reserve from Energy Storage. 25th March 2013
100
50
0
-50
-100
0
1
2
3
4
5
6
7
8
ES power [MW]
0.5
0
-0.5
15-min limit reached
-1
0
1
2
3
4
5
6
7
8
0
1
2
3
4
Time [h]
5
6
7
8
State of charge
0.95
0.9
0.85
0.8
0.75
Data recorded at site
Recordings from 2013-2014
Accum. duration of low frequency periods pr. month
Calculated energy [MWh] vs. frequency pr. month
4
80
Energy [MWh]
Duration [hours]
100
60
40
20
0
3
2
1
0
1
2
2
3
4
5
6
7
8
Month
9
10
11
12
49.97->49.98
49.95->49.96
49.93->49.94
49.91->49.92
49.89->49.9
49.87->49.88
49.85->49.86
Frequency [Hz]
3
4
Discharged during upward regulation
0.32 MWh/day
Charged
0.60 MWh/day
Absorbed for auxiliary power consumption
0.35 MWh/day
Duration of frequency below 49.98Hz
Under-frequency energy demand
16%
0.35 MWh/day
5
6
7
8
9
10
11
12
Month
49.97->49.98
49.95->49.96
49.93->49.94
49.91->49.92
49.89->49.9
49.87->49.88
49.85->49.86 Frequency [Hz]
Primary reserve tariff evolution in Western Denmark
Tariff for ENDK1 primary reserve up-regulation
140
120
Tariff [EUR/MWh]
100
80
60
40
20
0
0
Jan 1st 2013
100
200
300
400
500
Days
600
700
800
900
May 31st 2015
Net present value of green field investment
NPV, per-unit vs years
0,2
0
0
2
4
6
8
10 12 14 16 18 20
-0,2
2013
-0,4
2014
-0,6
Tariff for ENDK1 primary reserve up-regulation
140
120
-0,8
Tariff [EUR/MWh]
100
80
60
40
20
0
-1
0
100
200
300
400
500
Days
600
700
800
900
Simulation power/energy ratio for primary reserve
Simulations are based on 1 year grid frequency data (2012).
PFRAVA
[%]
120
100,00
100,00
100,00
100,00
99.94
99.82
99.06
95.70
84.63
72.26
48.39
100
110
PFR service availability [%]
ESS Capacity
(discharge time with
ESS full power )
15 min discharge time
10 min discharge time
7.5 min discharge time
6 min discharge time
5 min discharge time
4 min discharge time
3 min discharge time
2 min discharge time
1 min discharge time
0.5 min discharge time
0.1min discharge time
90
80
70
60
50
40
30
-2
0
2
4
6
8
10
12
ESS capacity [min]
14
16
18
20
Wind power plant + energy storage applications
Inertial Response +
Primary Reserve
Up-regulation by
energy storage system
Down-regulation by
wind power plant
12200
12000
Power oscillation damping
11800
11600
11400
11200
Pref_AWPP_kW
11000
P_Elspec_WPP_kW
10800
P_Elspec_WPP_kW
10600
0
500
1000
1500
2000
2500
3000
3500
Power smoothening
From 2012-13: www.ewea.org + www.twenties-project.eu
Conclusions and Perspectives
1. The TSO has approved storage units for primary reserve market participation.
2. Apparently the only installation of its kind in Scandinavia. Commercial operation for 3 years.
3. The 15-minute constant power discharge effectively sizes the capacity. Only used for up-regulation.
4. The observed network frequency excursions are very modest
Low utilisation of storage (2%).
5. Effective full-cycle efficiency is 50% (30% incl. aux power losses).
6. Specific algorithm developed and approved for control of storage charging.
7. If symmetric bids are required, SoC controller must be adapted (and business case erodes).
8. Recent reserve power tariff reduction erodes business case.
9. Storage cost reduction required and expected.
10. Installed storage capacity may be reduced if requirements were matched to actual frequency excursions.
This would increase utilisation rate. Main circuit efficiency should then be optimised.
11. Blending other ancillary services may increase earnings.
Thanks to:
Thank you for
your attention.
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