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siemens.com/power-technologies© Siemens AG 2015 Alle Rechte vorbehalten.
“German Experience on High Penetration through Renewables -
Challenges for System Stability”
Dr. Edwin Lerch, Siemens AG, EM DG PTI PSC DYS
E for E Seminar, Bangkok, August 2016
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 2 Dr. Edwin Lerch/EM DG PTI PSC DYS
Content
Global trends in the development of electrical systems
Generator and grid stability
The role of renewables in the future
Actions to be taken
Outlook
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 3 Dr. Edwin Lerch/EM DG PTI PSC DYS
Global developments until 2030
1 % Population Growth per year
3.0 % average Economic Growth per year
2.8 % average increase in power demand per year
in industrialized countries (OECD Countries) app. 1.3 % per year, additional power demand of 37 % by 2030 in total
developing and emerging countries more than 4.0 % per year,power demand of more than 250 % by 2030 in total
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 4 Dr. Edwin Lerch/EM DG PTI PSC DYS
Developments in power generationGlobal Tendency: Renewables become an important share of generation of the future
Installed Capacityin Gigawatt
21%16%20%
6%37%
1990
19%13%
27%7%
34%
2000
14%
7%
44%
9%
29%
2030
Western EuropeEastern Europe / CIS
Asia / Pacific
Africa / Middle East
Americas
Regionally
2,8353,620
8,800
12%17%15%
32%1%
23%
1990
10%22%14%
30%2%22%
2000
8%
26%
5%
29%
14%
18%
2030
Nuclear
Gas
Oil
Coal
By Energy Sources
2,8353,620
8,800
HydroRenewablesOther
Source: Siemens Energy, E ST MOP 3 - 2008
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Development of renewable generation in IndiaRadical new generation approach
Gen. Capacity 2016: 303 GW, 1106 TWh, peak deficit up to 10%
Growth 8 % / a, necessary generation capacity 2017 up to 440 GW
Wind generation 26.8 GW, PV 6.7 GW
3433 MW added wind power capacity 2015-2016
3019 MW added solar power capacity 2015-2016
31472 solar pumps installed 2015-2016
Target : >5 times increase in renewable power to 175 GW by 2022 (28%)
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 6 Dr. Edwin Lerch/EM DG PTI PSC DYS
Development in power generation Generation mix
SPP
Cost, efficiency and environmental concern drive technology development
Strong development in non-OECD
CCPP/SCPP
Efficiency improvement
Carbon capture technologies
Key solution to firm the intermittency of RES
Solar
PV, c-Si dominant and new technologies emerging
CSP heat transfer innovations
Wind
Strong market growth, China US as leaders
Technology innovations (direct drive; blades)
Others
i.e. Ocean power (tidal and wave power)
Hydro
Two types of technologies with steady growth
Strong development in China and Brazil
CCPP = combined cycle PP SPP = small PPSCPP = simple cycle PP CSP = concentrating solar power
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ENTSO-E – the European Grid Organizationsince 2009 – under one common grid code
since 2010
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German electric power supply system (614 TWh)Key data and selected issues – Transmission bottlenecks
Key data of German power system Peak demand 2014 80,000 MW Installed capacity 2014 194,000 MW Gas 15 % conventional 55 % Hard Coal 11 % Lignite 11 %
Wind 18 % (0.3 %) renewable 45 % PV 20 %
Supply non-availability 20.4 min/a 2014 renewables 25,3 % of energy generation To be built, 2014 – 2018 6,500 MW To be rebuilt 2014 – 2018 11,800 MW
Transmission bottlenecks North-South East-West International interconnections
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Motivation, Targets and Challenges to rebuild the GermanPower System (“Energiewende” energy turnaround)
Motivation: Replacement of fossil sources by renewable source
Reduction of CO2
Retirement of NPP‘s (Fukushima 2011)
Targets: Co2 reduction 80 % until 2050
Retirement of NPP‘s until 2022
Stake of renewables 45 % (2020) and 70 % (2040)
Challenges: Maximum utilization of renewables (potential, storage, losses)
Balancing of fluctuating sources by conventional power plants
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Developments in power generation Trends in Europe
NET ELECTRICITY GENERATING INSTALLATIONS IN THE EU 2000-2014 (MW)
Source THE EUROPEAN WIND ENERGY ASSOCIATION, WIND IN POWER, 2014 EUROPEAN STATISTICS, February 2015
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Development of Renewables in Germany
Installed capacity PV
PVWind onshore Wind offshore
Wind onshore Wind offshore
peak load Germany: ca. 80 GW (constant)Expected load until 2025
energy demand Germany 2011: app. 600 TWh (constant)Expected energy until 2025
installed 2020:Wind PV
51,0 GW + 51,7 GW∑ 102,7 GW
harvest 2020:Wind PV
138,8 TWh + 54,2 TWh∑ 193 TWh
:Wind on-shore 2000kWh/kW ->3000kWh/kW
Wind off-shore 4000kWh/kWPV 1000kWh/kW
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 12 Dr. Edwin Lerch/EM DG PTI PSC DYS
Predictability and Dynamics of Wind PowerExample: Vattenfall Europe
Windpower infeedLoad
12000
03/020
8000
4000
10/02 17/02 24/02
Powerin MW
Wind Power forecast
Error: -60%Error: +280%
Source: IfR, TU-Braunschweig, Vattenfall Europe Transmission, Feb. 2008
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Wind and PV infeed in Germany in 2011/12Time period 01.10.2011 to 31.03.2012
Source: EEG/KWK Transparenzplattform der ÜNB
peak PV peak wind
wind
PV
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Grid stability
Stability of generators after disturbances
Interarea oscillations
Frequency behaviour after generation outages
Balancing of frequency
Primary reserve stability
Voltage stability
Bottlenecks in transportation
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Inertia – Key parameter of system stability
TS = 2·XG·2HU2· N
K= f (machine param.)2·HdS =
G1G2
PL1=0
PG1
XL=0
QG1=0 SG2>>SG1H1
XG=Xd=Xq
SG1
U oscillation time
oscillations damping
Oscillation time depends on H, not on PG or SGOscillation damping depends on HTypical oscillation frequency 0.7 – 1.3 Hz (f = 1/T)
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System behavior after outage of generation
50
49
∆fs
app. 5 s
dtdPP
PHff
r
rd
22
2
r
r
PP
Hftf
2
/
fr grid frequency (Hz)H system inertia (MWS/MW)ΔP power lost (MW)Pr total power (MW)dP/dt activated reserve power (MW/S)
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Inter-area oscillation through system growth
0.1 to 0.5 Hz large inter-area in both systems
weak coupling
interarea oscillations
local modeIn system 1
local modein system 2
Interarea modesystem 1 and 2
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Primary Control Reserve in ENTSO-E(to cover outage of 2 NPP at one location)
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Wind Power Incidents in China
Wind Power Incidents in China
80 trip incidents In 2010, (15 resulted in the loss of 100 MW to 500 MW)*
193 turbine trip incidents in 2011, (54 resulted in the loss of 100 MW to 500 MW)*
* Wind Power Incidents in China: Investigation and Solutions Ming, Xue Song, Li Ling-yun, Cheng Huan, and Zhang Ge, School of Economics and Management, North China Electric Power University
“Offshore windfarms 'wild west' of renewable energy”
The Guardian
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Inter-Area Oscillations in Central Europe
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Voltage Stability Former NPP ‘Biblis A’ became synchronous condenser Reactive power to support voltage profile and voltage stability
Biblis A nuclear power plant shut down after Fukushima incident Generator 1,500 MVA
Modification into synchronous condenser Largest synchronous motor worldwide Reactive power support from -400 to
+900 MVAr Commissioned in February 2012
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Synchronous condenser supports voltage profileOperation of synchronous condenser Biblis A 13. to 19.03.2012
Volta
ge a
t Bür
stad
t 400
kV
subs
tatio
n
underexcited during
weekend and night
Reactive
power
output
reactive power
voltage
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 25 Dr. Edwin Lerch/EM DG PTI PSC DYS
Predictability and Dynamics of Solar Power
Source: Michael Weinhold & friends
Sunny Day, April: 1,9 MWh
Cloudy Day, April: 1,2 MWh
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Solar eclipse March 2015
Load and PV forecast normal Load and PV forecast during SOEC
Netzlastverlauf
PV-Einspeisungwolkenlos
PV-Einspeisungbedeckt
00:00 03:00 06:00 09:00 21:0018:0015:0012:00
PV-Einspeisungwolkenlos
PV withclouds
00:00 03:00 06:00 09:00 21:0018:0015:0012:00
Netzlastverlauf
forecast
load load
PV without clouds PV without clouds
PV with clouds
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 28 Dr. Edwin Lerch/EM DG PTI PSC DYS
Destabilization of grid frequency by renewables
large penetration by renewables → destabilisation of frequency stability
No share of synchronizing torque → ROCOF (rate of change of frequency) is
increasing
Normal value < 0.5 Hz/s
Expected up to 1 Hz/s (today), up to 3 Hz/s (in the future)
reasons:
- underexcited operation of PP‘s with low load
- airgap torque very small
- large ROCOF are combined with large oscillations
- less generation with full load instead of many generators in part load (H reduced)
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Dec. 2014 grid instability in Ireland by 37 % wind(part load → full load (H = 2 sec)
Source: Uni Rostock
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 32 Dr. Edwin Lerch/EM DG PTI PSC DYS
Dena* Investigation: Necessary primary reserve
alternative sourcesconventional
*German Net Agency
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Elimination of conventional power plantwinter scenario
Quelle: Uni Rostock
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 34 Dr. Edwin Lerch/EM DG PTI PSC DYS
Elimination of conventional power plantwinter scenario
Quelle: Uni Rostock
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 35 Dr. Edwin Lerch/EM DG PTI PSC DYS
Elimination of conventional power plantwinter scenario
Quelle: Uni RostockOverflow of production
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 36 Dr. Edwin Lerch/EM DG PTI PSC DYS
Elimination of conventional power plantwinter scenario
Quelle: Uni RostockOverflow of production
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 37 Dr. Edwin Lerch/EM DG PTI PSC DYS
2016, May 15: Marking a milestone for chancellorAngela Merkels ‚Energiewende*‘ - policy
May 8 clean energy 95 % of power needs
May 15 clean energy (wind & solar) met pretty much 100 % ofGermany‘s power needs (45.8 GW)
• for several 15 min power price turned negative (57 $ / MW)
• Commercial customers were being paid to consume electricityfor few hours
Power system still to regid for suppliers and consumers to respond quicklyto price signal
*Energiewende: energy turnaround
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Highly efficient Combined-Cycle Power PlantIrsching 4 will be retiered?
ƞ= 60,7 %world record 2011
Perspective 2015 (E.ON): „the economic perspective of the plant is very critical“
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Ancillary services for system operation and stabilityAll parties involved have to contribute
frequencyvoltage supply operation
• reactive power
• voltage
• power
transportation
• power control
• re-dispatch
• primary
reserve
• black start
capability
• congestion
management
• monitoring
• generation
management
• DSA / PSA
• adjust market for renewables to support ancillary services• coordination between all parties concerned• guaranty of profitability for all parties• timely requirements are necessary
What isnecessary?
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Technical Capabilities of Offshore Wind Farms for the Provision of Ancillary Services
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 41 Dr. Edwin Lerch/EM DG PTI PSC DYS
Technical Capabilities of Offshore Wind Farms for the Provision of Ancillary Services
The Future: Synthetic Inertia Capability
power of WF
breaking energyfrequency
wind energy
ancillary energy
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 42 Dr. Edwin Lerch/EM DG PTI PSC DYS
Solar Inverter
Central Inverter
Parallel PVs are connected to the same DC input of the central inverter
(high efficiency, low losses) ↔ reliablity depending on power of working PV cells)
String Inverter
Modularization by parallel strings: max. power tracking peak at DC side
grid-tied at AC side
Advantage: decoupling of modules and shadow
high reliability
master-slave concepts
team concepts
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Power Electronics for grid-connected PV systems
PV arrayBoostDC-DCconverter
Ipv Pac
DC Output~Vpv
single-phaseDC-ACinverter
Pac(t) iac
> >> >Vpc
energystorage
PV set pointto MPP
generateiac in phasewith Vac
Operate PV array at MPP
Generate AC output current in phase with AC grid voltage
Achieve high power conversion efficiency
Provide energy storage to balance difference between Ppv and pac(t)
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 44 Dr. Edwin Lerch/EM DG PTI PSC DYS
From PV array current to Ppv
Source ECEN2060
depending on sun intensive and temperature
adjust Ipv = Iref to operate at MPPPV converter operates as CCI (current controlled inverter)
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Comparison of synchronous generators and inverters
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 46 Dr. Edwin Lerch/EM DG PTI PSC DYS
The „electrical meaning“ of inertia
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 47 Dr. Edwin Lerch/EM DG PTI PSC DYS
Proposed frequency controller for VCI‘s
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 48 Dr. Edwin Lerch/EM DG PTI PSC DYS
Simulations – Mixed Scenario
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 49 Dr. Edwin Lerch/EM DG PTI PSC DYS
50.2 Hz Problem in Germany
• Problem:
PV converter are disconnected at 50.2 Hz (grid wide)
With 25 % PV disconnected suddenly high risk of black out
• Countermeasures
Change of converter >10 KW (LV), >30 KW (MV)
Change of power generation by PV plants between 50.2 – 51.5 Hz with 40 % gradient reduced /increased (droop characteristic)
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Challenges for all parties concerned
Storage- realistic solutions: gas storage, LNG - decentralized solutions today available- combination of wind power and pump storage plants- storage of energy at wind generators (DFIG with capacitor banks)
Stability- limited by inertia of conventional plants- faster control (FACTS, faster and more flexible conventional plants)- renewables with virtual inertia- power electronic (PE) with inherent ‘inertia’ / current source control -> voltage source control
Fluctuation- stress, wearout and high dynamic (conventional and renewable plants)
Frequency gradient- 0.5 Hz/s – 3 Hz/s acceptable for the grid? → countermeasures through PE
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 51 Dr. Edwin Lerch/EM DG PTI PSC DYS
Challenges for all parties concerned
Ancillary services• are necessary from all parties concerned
System dynamic• lifetime reduction – intelligent maintenance concepts• more flexible power plants• faster reaction• part load operation• more start/stop cycles• faster start up (Irsching CCPP warm startup to 100 % in 30 min)• new concepts (CCPP, single shaft with couplings between turbines and generators)
Operation, Monitoring• more flexibility (LV transformers with on-load tap changer)• fast re-dispatch• more information are necessary• PMU monitoring (and control)• DSA for operation at the system stability limits
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 52 Dr. Edwin Lerch/EM DG PTI PSC DYS
Net Metering in Germany
Two meters (infeed, consumption) or bi-directional meter
Often not attractive as feed-in-tariff, depending on solar intensity and capital amortization
Actual market price not easy to calculate depending on power consumption under different customer profiles
Typical price per kWh 28.7 ct
Infeed compensation tendency(<30 kW):
<2009 50 ct/kWh
2010-2012 39-24 ct/kWh
2016 13 ct/kWh
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 53 Dr. Edwin Lerch/EM DG PTI PSC DYS
The future of renewables in Thailand (1)
Bangkok Post April 2016:
- Solarelite plans 15 PP‘s concentrating solar power (135 MW)
- Farm cooperatives have won the right to sell 280 MW of solar power to the national grid
- 167 cooperatives to enter lucky draw (835 MW) – restricted supply infeed capacity
„The day when even small households households will be able to sell the solar power theygenerate back to big power companies and the government, and make a profit from it, isfast approaching“
2005 2007 2009 2011 2013 2015
24 MW 32.5 MW 43.2 MW 243 MW 823 MW 1330 MW
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The future of renewables in Thailand (2)
“During my term of office as the EGAT Governor for 1 year and 10 months, I will focus on community development to show that power plants can stay with the communities in harmony. At the same time, I will develop renewable energy to the full extent of its potential together with coal power to balance the energy use, strengthen power security, and maintain proper cost of electricity for the competitiveness of the country with the concern on global warming solutions” (Mr. Kornrasit Pakchotanon, July 1, 2016)
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 55 Dr. Edwin Lerch/EM DG PTI PSC DYS
Economic consequences following the „Energiewende“ (energy turnaround)
e.on (German TNO) worth 100 billion $ before the turnaround 2011
worth new 20 billion $ !
Do not under-estimate the speed of change from a classical energy system
to a system with high penetration of renewables
with all technical and economical consequences
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 56 Dr. Edwin Lerch/EM DG PTI PSC DYS
The future are renewables
When we stop and control the challenges power systems with high penetration of renewables
can be operatedsave and reliable
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 57 Dr. Edwin Lerch/EM DG PTI PSC DYS
Thank you very much for your attention!
Dr. Edwin LerchPrinciple Expert System DynamicEM DG PTI PSC DYS, Siemens AG
Head of “Grid Control and System Guidance” VDE association, Germany
Tel.: +49 (9131) 7-34052Fax: +49 (9131) 7-35159Mobil: +49 (171) 7682176
E-Mail: [email protected]
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 58 Dr. Edwin Lerch/EM DG PTI PSC DYS
Thailand: Power Generation Capacity (2012)
Fossil Fuel 28 GW
Hydro Plants 3.4 GW
Hydro Import 2.2 GW
Renewables 2.8 GW
Biomass 1.96 GW
Solar 0.39 GW
Wind 0.11 GW
Small Hydro 0.1 GW
→ PV Roof top Program 2013
Solar Power Target 2036 6 GW (2013 - 0.7 GW, 2015 - 2.5 GW)
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Solar Potential and PV Development in Thailand
• 14 % of the country has solar exposure of 20 MJ/m2/day
• 50 % of the country has solar exposure of 18-19 MJ/m2/day
• Bangkok 5.04 h of sun per day
• 2015 adder schema replaced by feed-in tariff (new 1000 MW potential)
PV Development
2005 2007 2009 2011 2013 201524 MW 32.5 MW 43.2 MW 243 MW 823 MW 1330 MW
On-grid 1299 MWOff-grid 30 MW
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Map of Renewable Energy Power Plant in Thailand
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Net Metering
• Allows consumers who generate some (or all) of their own electricityto use it anytime instead of when it is generated
• Meter works in 2 directions (measure power purchase larger power production or measure power return to grid (customer pays thenet of both directions)
• Originated in the US (small wind turbines, small PV plants)
• Used in UK, Canada, Philippines, Brazil, Australia, Denmark, Italy, Spain…
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 62 Dr. Edwin Lerch/EM DG PTI PSC DYS
Net Metering
• Controversy of different interests
• Benefits of distributed energy overweights in costs
• Shared by all ratepayers
• Reduces needs of centrelized power plants
• Grows of rooftop solar
• Social benefits
• Owners of generation system do not pay the full cost of service to use the grid
• Shift of generation owner shares to customers without distributed generation (paid by other users)
• Solar rooftop owners still rely on the grid to receive electricitywhen generation is not available
© Siemens AG 2015 Alle Rechte vorbehalten.Seite 63 Dr. Edwin Lerch/EM DG PTI PSC DYS
Net Metering
Different tariffs
Feed-in-tarifs above retail, reduces to retail as the percentageof adopters increase
Net-metering at retail, not technically compensatedmay become compensated if there is excessgeneration and payments are allowed by utility
Power purchase agreement compensation below retailcan be above (solar at peak load conditions)