current problems and applications for power … problems and applications for power electronics in...
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Current problems and applications for
Power Electronics in Renewable Energyby
Prof. Frede BlaabjergllFellow IEEE
Distingueshed Lecturer IEEE-IAS
Aalborg UniversityInstitute of Energy Technologygy gy
Denmark
1
C t bl d li ti f Current problems and applications for Power Electronics in Renewable
Energy Energy
A lb U i itOutline
1. Aalborg University2. Challenges3. Wind Power4. Solar Power5. Conclusions
2
1 Aalborg University1. Aalborg University
3
Aalborg University - DenmarkWhere are we from?
rsit
y U
niv
eral
bo
rg
Aa
4• Project-organised and problem-based
Aalborg University - Denmark
R 180 i E
Engineering and Science
∙ Revenue : 180 mio Euro
∙ Employees : 1500rsit
y
Employees : 1500
∙ Brutto area 140.000 m2
Un
iver
▫ Research 73.744 m2
▫ Education 53.188 m2
▫ Administration 1.731 m2alb
org
▫ Other 11.439 m2
∙ Ph.D. : 500
Aa
Ph.D. : 500
∙ Departments : 10
5∙ Schools : 4 (Appr. 30 Bachelor, 60 Master)
Energy TechnologyActivities – Energy TechnologyCOMMUNICATIONCOMMUNICATION
SOLAR CELLS
WIND TURBINEREFRIGERATOR
TELEVISION
3
DC
SOLAR CELLS
WIND TURBINEREFRIGERATOR
TELEVISION
3
DC
PRIMARY FUEL
EnergyStorages
rsit
y
HEATLOADS
POWER STATIONMOTOR
PUMP
LIGHT
TRANSFORMER
TRANSFORMERSOLAR
ENERGY
3 3 3 1-3
DCAC
POWER STATIONMOTOR
PUMP
LIGHT
TRANSFORMER
TRANSFORMERSOLAR
ENERGY
3 3 3 1-3
DCAC
FACTS/CUPSUn
iver
ROBOTICS
INDUSTRY
POWER SUPPLY
COMPEN-SATOR
FUELCELLS
TRANSPORT
ROBOTICS
INDUSTRY
POWER SUPPLY
COMPEN-SATOR
FUELCELLS
TRANSPORT
DCAC
DCAC
CHPEnergy
Storages
alb
org
=ac dc
FUEL
COMBUSTIONENGINE
TRANSPORT
~=
ac dc
FUEL
COMBUSTIONENGINE
TRANSPORT~A
a
Keywords: Energy production – Energy distribution – Energy consumption – Energy controlENGINEENGINE
66
20 Prof
60 PhDOrganisation Energy Technology
10 Guest Researchers
10 Research Assistants
15 Technician
Department of Energy Technology
Power Systems
Thermal Energysystems
ElectricalMachines
Fluid PowerSystems
PowerElectronicSystems
Fluid Mechanics and
Combustionrsit
y
Strategic Networks:• EMSD
Lab. Facilities:• Power electronics
Systems
y
Wind Turbine Systems
Multi-disciplinary research programmes
Un
iver
• EMSD• EDS• CEES• NEED• FACE• ECPE
Systems• Drive Systems Tests• Hydraulic• Power systems• High Voltage• DSpace
y
PV
Biomass
Wave Energy
alb
org
• ECPE• VE-NET• NIK-VE• DUWET• WEST
VPP
• DSpace• Laser Systems• Fuel Cell Systems• Proto Type Facilities• Biomass conversion
facilitiesFuel cell Systems
Modern Power Systems
PV
Aa
• VPP facilitiesAutomotive & Industrial Drives
Energy Harvesting / TEG
Efficient & Reliable PE Design
77
e gy a est g / G
Emergent Projects
Green Buildings
Aalborg University - Campus
8
2 Challenges2. Challenges
9
E d P Ch llEnergy and Power Challenge
The Modern Human Challenge:
• Water – few days
F d f kenge
s
• Food - few weeks
• Energy – decades but necessaryCha
lle
• Land to live on ?
• Others ?
10
E d P Ch llEnergy and Power Challenge
Main challenges in energy :
• Sustainable energy production (backbone weather based)• Sustainable energy production (backbone, weather based)
• Energy efficiency
Mobilityenge
s
• Mobility
• InfrastructureCha
lle
Different initiatives :
- EU Set-plan (20-20-20) and beyond
- Danish Climate Commision
- Many other countries
11
- Globally many initiatives
Energy and Power Challenge
Energy comsumption increases More people (born, longer life-time etc.)p p ( , g ) More equipment Higher living standard More production
l b l k b d l d Global Energy Market becomes deregulated (electrical power, natural gas, etc.)
Climate Change a matter to be adressed
enge
s
( bl )
Therefore
Cha
lle
New power sources interesting (E.g. renewables) Towards E-based society More efficient use of the existing source Power balance extremely an issue to adress Power balance extremely an issue to adress New energy storage devices
Power Electronics and Power Converters
12
Power Electronics and Power Converters are Enabling Technologies for us!
Energy and Power Challenge
• Early developers shift around $15,000 per capita ($1997 PPP) as less energy-intensive services dominate economic intensive services dominate economic growth
• Signs of saturation beyond $25,000
• Later developers require less energy
enge
sCha
lle
Source: Energy Needs, Choices and Possibilities – Scenarios to 2050 (Shell International 2001)
PPP = Purchasing Power Parity
13
Energy and Power Challenge
W ld t ti l World potential map
enge
sCha
lle
14
Dispersed based power production
Traditional Power System ArchitectureTraditional Power System Architectureen
ges
Cha
lle
• Centralized energy production
• Unidirectional power flow
15
• Vertical operation and control
Active Networksen
ges
Cha
lle
Possible evolution of passive distribution networks.
Enabling technologies:
16
Enabling technologies: (1) Power electronics(2) New ICT
Renewable Energy SystemsRenewable Energy Systemsen
ges
Important issues for power converter
Cha
lle
Important issues for power converter• reliability and thereby security of supply• efficiency• cost• volume• power electronics enabling technology• protection
t l ti d ti
17
• control active and reactive power• ride-through and monitoring
3 Wind Power3. Wind Power
18
Power Conversionr
GridWind P
ower
Wind
Win
d
Aerodynamic Transformer
Gearbox
Generator PowerElectronic
19
ElectronicInterfacecontrol
Wind Power Directions
Windforce 10: • 2010 180 GW
Installed Wind Power in the World- Annual and Cumulative -
30 000
35,000
40,000
120 000
140,000
160,000
r
• 2020 1200 GW
15,000
20,000
25,000
30,000M
W p
er y
ear
60,000
80,000
100,000
120,000
Cum
ulat
ive
MW
Pow
er
0
5,000
10,000
15,000
0
20,000
40,000
60,000 C
Win
d
Global Wind Power StatusCumulative MW by end of 2001, 2004 & 2007
1983 1990 1995 2000 2005 2009
YearSource: BTM Consult ApS - March 2010
Cumulative MW by end of 2001, 2004 & 2007
40,000
50,000
60,000
10,000
20,000
30,000
20Source: BTM Consult 2010
0Europe USA Asia Rest of World
2001 (24,927 MW) 2004 (47,912 MW) 2007 (94,005 MW)Source: BTM Consult ApS - March 2008
Wind Turbine Developmentr
Pow
erW
ind
• Bigger and more efficient ! • 3 6-6MW prototypes running (Vestas GE Siemens Wind Enercon)
21
• 3.6-6MW prototypes running (Vestas, GE, Siemens Wind,Enercon)• 2 MW WT are still the "best seller" on the market!
EU St t
Wind Power Systems
EU Statusr
Pow
erW
ind
2222
Wind Turbine Concepts
Fixed Speed Wind Turbinesr
• 2 squirrel-cage induction generators (power ratio 1:4) P
ower
g (p )• small –very low wind speed• large – rest of the range
• variable capacitor bank• pasive/active stall control
AdvantagesWin
d
• pasive/active stall control• robust -> to grid faults• cheap
DrawbacksR i tiff id f t bl ti• Requires a stiff grid for stable operation
• does not support speed control• its mechanical construction must be able to support high mechanical stress
23
Wind Turbine Concepts
Variable Speed Wind Turbines – Road mapsr
Pow
erW
ind
24
Variable Speed Wind Turbines
Wind Turbine Concepts
Variable Speed Wind Turbinesr
Pow
er
• wound-rotor induction generator • Variable pitch – variable speed• 30% slip variation around synchronous speed • power converter (back2back / direct AC/AC) in rotor circuit
Win
d
• power converter (back2back / direct AC/AC) in rotor circuit
Advantages• smooth reactive power control
Drawbacks • use slip-rings -> maintenance
• smooth grid connection• reduced mechanical loads on the WT tower
25
use slip rings > maintenance• power converter sensitive to grid faults -> complicated protection schemes
Wind Turbine Concepts
Variable Speed Wind Turbinesr
Pow
er
• variable pitch – variable speed• with/without gearbox • generator
• synchronous generator
Win
d
• synchronous generator, • permanent magnet generator• squirrel-cage induction generator
• power converter• diode rectifier+boost DC/DC+inverter• back2back• direct AC/AC (matrix, cycloconverters, etc)
26
Wind Turbine Concepts
Variable Speed Wind Turbinesr
Pow
er
Synchronous generator with field winding
Win
d
Permanent Magnet Synchronous Generator
27Squirrel-Cage Induction Generator
Wind Turbine Concepts
Variable Speed Wind Turbines
r P
ower
Win
d
• multiple stator windings• paralleled power convertersp p
• better efficiency at low wind speed• redundancy
• used by some manufacturers
28
Power Electronic Convertersr
Back-to-back two-level voltage source converterProven technology P
ower Back-to-back VSC
Standard power devices (integrated)
Decoupling between grid and generator (compensation fornon-symmetry and other power quality issues)
Win
d
Demands
y y p q y )Need for major energy-storage in DC-link (reduced life-time and
increased expenses)Power losses (switching and conduction losses)
DemandsReliableMinimum maintenanceSolution competitive economically
29
Low power lossesPhysical size limitedWeight limited (if in nacelle)
Multi-level topologies +6 MW
bi
nes
nd T
urb
s fo
r W
i
nver
ters
wer
Con
Pow
30
Multi-level topologies +6 MW
bi
nes
nd T
urb
s fo
r W
inv
erte
rsw
er C
onPo
w
31
Multi-level topologies +6 MW
Comparison Multi-levelbi
nes
nd T
urb
s fo
r W
inv
erte
rsw
er C
on
• Reliability
• Efficiency
Pow
32
y
• Price
• System solutions
Doubly-Fed Wind Turbinerb
ines
Win
d Tu
trol
of W
DFIG t l l l Wi d t bi t l l l
Con
t DFIG control level: Control for DFIG:
active& reactive power Control of grid side converter
Wind turbine control level: pitch control power limitation control
Targets for control:
g DC-link voltage unity power factor
33
maximum power point operation power limitations for high wind speeds reactive power control
Full Scale Power Converter Wind TurbinePermanent Magnet Synchronous Generator
rbin
esW
ind
Tutr
ol o
f W
PMSG t l l l Wi d t bi t l l l
Con
t PMSG control level: Maximum power point Control of grid side converter
DC-link voltage
Wind turbine control level: pitch control power limitation control
Targets for control: maximum power point operation
g unity power factor
34
maximum power point operation power limitations for high wind speeds reactive power control
Low Voltage Fault Ride-through CapabilityGrid Codes
sre
men
ts
x= 300-500 ms
on R
equi
Successive & non-symmetrical faultsLVRT
onne
ctio E-On Grid Code
Grid
Co
3535
Grid support by 100% reactive current injection
Next Generation WT Capabilities
Uniform dynamic performance of WT
p
Integration of energy storage elements in each WT
36The system structure of a variable speed wind turbine integrating
with a battery storage system
Vestas Wind Systems A/S Denmark
Current DevelopmentVestas Wind Systems A/S Denmark
olog
ies
e Te
chno
d Tu
rbin
e
Vestas V164 off-shore turbineRated power: 7,000 kW Rotor diameter: 164 m Hub height: min 105m
Win
d
Hub height: min. 105mTurbine concept: medium-speed
gearbox, variable speed, variable pitch, full-scale power converter
Generator: permanent magnetT t k t Bi ff h f
3737
Generator: permanent magnetTarget market: Big off-shore farms
Enercon GmbH Germany
Current DevelopmentEnercon GmbH Germany
olog
ies
e Te
chno
Enercon E-126 gearless turbineRated power: 7,500 kW d
Turb
ine
Rated power: 7,500 kW Rotor diameter: 127 m Hub height: 135 mTurbine concept: Gearless, variable
speed variable pitch control
Win
d
speed, variable pitch control Generator: Enercon direct-drive
annular generator
3838
Target market: Big on-shore and off-shore farms.
Nordex Germany
Current DevelopmentNordex Germany
olog
ies
Nordex N150/6000Rated power: 6,000 kW Rotor diameter: 150 m
b h i h 00e Te
chno
Hub height: approx.100 mTurbine concept: Gearless, variable
speed, variable pitch control Generator: permanent magnetd
Turb
ine
Win
d
3939
Target market: Big off-shore farms.
Siemens Wind Power Denmark
Current DevelopmentSiemens Wind Power Denmark
olog
ies
e Te
chno
Siemens SWT-3.6-120Rated power: 3,600 kW Rotor diameter: 120 m
d Tu
rbin
e
Turbine concept: 3-stage gear, variable speed, variable pitch control
Generator: Asynchronous
Win
d
y
New Generation : PM generator and without gearbox
4040
Target market: Big off-shore farms.
The Global Players in 2009
Top-10 Suppliers in 2009% of the total market 38,103MW
ENERCON (GE) 8.5%
GOLDWIND (PRC) 7.2%
DONGFANG (PRC) 6.5%
GAMESA (ES) 6.7%
SINOVEL (PRC)sion
SUZLON (IND) 6.4%
( ) 9.2%
Con
vers
REPOWER (GE)
SIEMENS (DK) 5.9%
GE WIND (US)12 4%Po
wer
C
Others 18.5%
REPOWER (GE) 3.4%
VESTAS (DK) 12.5%
12.4%
Win
d P
Source: BTM Consult ApS - March 2010
41
Possible Topologies Wind Farms
DFIG Wind Turbines
Far
ms
Win
d
AC ff h id• common AC off-shore grid• step-up transformer• AC connection to on-shore station• limited grid support during faultsg pp g
42
Possible Topologies Wind Farms
SCIG based active stall Wind Turbines with HVDC connection
arm
sW
ind
FaW
• common AC off-shore grid• DC-link connection• full grid support during faults• black-start capability
43
black start capability
Possible Topologies Wind Farms
Full scale Power converter based Wind Turbines with common DC grid
Far
ms
Win
d
• direct driven or gearbox• common DC off-shore grid• DC-link connection to on-shore PCC• full grid support during faults
44
full grid support during faults• black-start capability
Comparison Wind Farms F
arm
sW
ind
45
Horns Rev Vestas V80 2 0 MW
Off-shore developmentHorns Rev - Vestas V80–2.0 MW
Horns Rev 160 MWog
ies
tech
nolo
-sho
re t
Rotor Diameter 80 mHub Height 70 mWeight 245 tons• 80 x 2MW (Vestas V80 pitched
Off- Weight 245 tons
Start Wind 4 m/sNominel Wind 13 m/sMax Wind 25 m/s
• 80 x 2MW (Vestas V80, pitched, variable-speed, DFIG with gearbox)
• In operation for more than 3 /Platform for helicopter hoistImproved Power ControlImproved Corrosion ProtectionI d HSE F iliti
years
46
Improved HSE Facilities
Off-shore development
Nysted wind farm 158.4 MWog
ies All turbines in operation
Sept 12, 2003
tech
nolo
-sho
re t
Off-
O&MService once a year• Automated greasing• Automated greasing• extended SCADA• Access by boat
47
r P
ower
4 Solar Power
Sol
ar 4. Solar Power
48
The resource
49
Solar cell technologies
∙ Monocrystalline Silicon
g
Polycrystalline Siliconff
Amorphous silicon Thin filmSilicon
• Efficiency: 12 – 18 %• Shape: round /
quadratic• Colour: black / dark-
bl / bl i h
• Efficiency: 10 – 22 %• Shape: quadratic• Colour: blueish,
shimmer• Peak power, app.:
• Efficiency: 4 – 9 %• Shape: slim ribbons• Colour: black / dark
brown• Peak power app :
• Amorphous Si, cadmium telluride, copper indium diselenide and many new others!r blue / blueish
• Peak power app.: 120 Wp/m2
• Price app. 4-5 € /Wp (continuously d i b 7%
p , pp100 W/m2
• Price app. 3-4 €/Wp
• Peak power, app.: 50 Wp/m2
• Price app. 5-6 €/Wp• can be foldable
• Efficiency up to 11 % • Can be deposited on
any surface• Colour depends on
t i l Pow
er
decreasing by ca 7% p.a.)
materials• Can be clear films
mounted on windows or roof tilesS
olar
50
Very fast development on Thin FilmOrganic cells with very low manufacturing cost but still short life time are emergingMulti junction cells with efficiency higher than 40% are reported!
Concentrating solar Photovoltaic Power - CPV
• Sun light concentrated with lenses or optical concentrators up to x500 typ. with trackingHi h ffi i /hi h t ili
Source: Amonix
• High efficieny/high temp silicon solar cells or advanced III-IV multi-junction technology (~40% eff)C id bl l l ll r • Considerable lower solar cell material
• Potential lower overall cost than PV
• Fresnell lenses concentrator with tracking P
ower
• Dish technology• Two-axis tracking dishes
• 200-500 kWe -commercial,MW plants - near term
• 25 kWp unit/850W/m2
• 26.6% efficiency triple-junctionsolar cells
• X 250 concentration
Sol
ar
• Two-axis tracking dishes• CPV panels in the focus of the
dish
• X 250 concentration• DPGS/Stand alone/pumping/• desalinization/H2 production
• CPV developmentsSource: NREL
• Solid concentrator
• 18 Mwe installed up to 2006• 6 years field experience (young!)• 38% efficiency solar cells now, 50% by 2010• 40% efficiency for H2 production now!
Source: NREL
51• CPV farm in Alice Spring, Australia of
20kW units
• 40% efficiency for H2 production now!• 2-3 Eurocent/kWh on long term
Technology Developmentr
Pow
erS
olar
52
Solar cells manufacturing r
Pow
erS
olar
53
• Crystalline silicon cell manufacturing high energy demanding. Cost is saturating• Thin film technologies – higher potential for cost reduction on long-term
Global PV Power Capacityr
Pow
erS
olar
• 7 2 GWp installed in 2009 despite financial crisis7.2 GWp installed in 2009 despite financial crisis • EU is leading (70%), Italy and Czech Republic are emerging• USA and China are growing fast their capacities• Several PV parks > 40 MWp in Spain, Germany and Portugal
54
Several PV parks 40 MWp in Spain, Germany and Portugal
PV Inverters
Source: Danfoss Solar
r
Directly convert the dc power from solar panels to grid synchronized power Pow
er
Typical requirements:
•“Very” high efficiency typ > 95% (large variety of innovative topologies!)
• “Very accurate” Maximum Power Point Tracking MPPT (typ >99% eff)Sol
ar
• Grid connection standard requirements (apply to certain countries)
• High performance grid monitoring and synchronization
• Active Anti-islanding algorithms
• Isolation,, leakage current monitoring, and dc current injection monitoring
• High power quality (low current THD)
Typically IGBT/MOSFETS and DSP technologies are used
55
Due to increased complexity and smaller market the cost of PV inverter is significant higher than the inverters for drives. Typ.400-500 €/kW
Photovoltaic System Costr
Pow
erS
olar
System cost is expected to drop to 2 5€/Wp by 2012 (optimistic!) System cost is expected to drop to 2.5€/Wp by 2012 (optimistic!) Due to the silicon shortage during the last years the cost reduction
will be delayed
56
Photovoltaic System Cost - predictionr
Pow
erS
olar
• Due to the silicon shortage during the last years the cost g g yreduction was delayed but now prices are going down fast
• First Solar announced 1$/Wp for thinfilm panels in 2010 (manufacturing cost)
57
( g )• For large PV systems cost is about 2.5€/Wp
Photovoltaic System Cost - comparsion
/kW
h
r €/
Pow
erS
olar
58
Maximum Power Point Tracking
• PV cells/panels exhibit a non-linear I-V characteristic – there is an optimum working point where the extracted power is the maximum (MPP) • The MPP depends on environmental conditions a Maximum Power Point Tracking (MPPT) system is needed to follow the changes• Most of the actual MPP tracers are hill-climbing methods – no knowledge of the PV string type or environmental conditions requiredr
0
d
g yp q
The most used technologies are:
Pow
er
dP/dV > 0
dP/dV < 0
• Perturb & Observe• Incremental Conductance• Constant Voltage
P iti C it
Sol
ar
• Parasitic Capacitance
Combinations of the above methods are often used
59
PV System Configurationsr
Pow
er
Central inverters• 10 kW-250kW, three-phase se e al st ings in
Module inverters• 50-180W, each panel has its own inverter
String (Multi)inverters• 1.5 - 5 kW, typical residential application
Sol
ar
phase, several strings in parallel• high efficiency, low cost, low reliability, not optimal MPPT
has its own inverter enabling optimal MPPT• lower efficiency, difficult maintenance•highercost/kWp
application• each string has its own inverter enabling better MPPT • the strings can have different orientations
High efficiency Mini central PV inverters (8 15 kW) are also emerging for
optimal MPPT•Used for power plants
•highercost/kWporientations•Three-phase inverters for power < 5kW
6060
High efficiency Mini-central PV inverters (8-15 kW) are also emerging for modular configuration in medium and high power PV systems
Topologies for PV inverters
on the LF side
with DC-DCconverter
with isolation
without isolation
on the HF side
r PVInverters
without DC-DCwith isolation
Pow
er
converterwithout isolation
Sol
ar
• The question of having a DC-DC converter or not is first of allrelated to the PV string configuration.
H i l i i d l id lt lik i US d• Having more panels in series and lower grid voltage, like in US andJapan, it is possible to avoid the boost function with a dc-dcconverter. Thus a single stage PV inverter can be used leading tohigher efficiencies.
61
g
Test of Commercial products (Photon)
Efficiency
r P
ower
Sol
ar
Weight
Volumen
62
PV inverters with boost converter and isolationisolation
DC
ACGridPV
Array
DC
DC
DC
ACGridPV
Array
DC
AC
AC
DC
r On low frequency (LF) side On high frequency (HF) side
Pow
erS
olar
Both technologies are on the market! Efficiency 93-95%
Boosting inverter with HF trafo based on FB boost converter [2] Boosting inverter with LF trafo based on boost converter
6363
Both technologies are on the market! Efficiency 93-95%
Parasitic Capacitancep
G-PVC
Frame
Glass
Cr
G-PVC
Substrate
PV-cell
G-PVC
G-PVI
Pow
er
• PV panel array has large surfaceSol
ar
p y g• Parasitic capacitance formed between grounded frame and PV cells• Its value depends on the:p
Surface of the PV array and grounded frame Distance of PV cell to the module Atmospheric conditions and dust which can increase the electrical Atmospheric conditions and dust which can increase the electrical conductivity of the panel’s surface
14-Apr- 64
Leakage current
G PVIG PVI
g
PV
Arr
ay
Filte
r
G-PVIG-PVI
r F
G-PVCG-PVI P
ower
• Charging and discharging this capacitance leads to ground leakage currents (unsafe for human interaction; damage PV S
olar
panels)• Amplitude of leakage current depends on
Value of parasitic capacitance Amplitude and frequency of imposed voltage
• RCM (Residual Current Monitoring) unit for monitoring leakage ground currentsleakage ground currents
14-Apr- 65
High efficiency topologies derived from H-bridgeHERIC (Sunways) -ηmax= 98%
r P
ower
Sol
ar
Two 0 output voltage states possible: S+ and D- = ON and S- and D+ = ON The switching ripple in the current equals 1x switching frequency high filtering needed Voltage across filter is unipolar low core losses VPE is sinusoidal has grid frequency component low leakage current and EMI
6666
High efficiency 98% due to no reactive power exchange as reported by Photon Magazinefor Sunways AT series 2.7 – 5 kW single-phase
Control of PV invertersr
Pow
er
dcVdcIi
*I gI
Sol
ar
*dcV v *
gI
gI g
gV
*sin inv×
Single-stage PV grid-connected system
67
Control Structure Overview+ L
PV PanelsString
dc-dcboost
LC LLow pass
filterC
-N
Trafo&
G rid
dc-acPW M -V SI
VPV
IPV
A ti I l di G id /PV l t
Ig
Vg
VdcPW M PW M
Basic functions (grid conencted converter)
CurrentControl
VdcControl
G ridSynchronization
r Anti-IslandingProtections
Grid /PV plant M onitoring M PPT
Active filtercontrol
Grid support(V ,f,Q )
Ancillary functions
PV specific functions
M icroGridControl P
ower
Ancillary functions
Basic functions – common for all grid-connected invertersGrid current control
THD limits imposed by standardsStability in case of grid impedance
PV specific functions – common for PV invertersMaximum Power Point Tracking –MPPT
Very high MPPT efficiency in
Ancillary Support – (future?)Voltage ControlFrequency controlFault Ride-through
Sol
ar
Stability in case of grid impedance variationsRide-through grid voltage disturbances (not required yet!)
DC voltage controlAdaptation to grid voltage variationsRide-through grid voltage
Very high MPPT efficiency in steady state (typical > 99%)Fast tracking during rapid irradiation changes (dynamical MPPT efficiency)Stable operation at very low irradiation levels
Q compensationDVR
Ride-through grid voltage disturbances (optional yet)
Grid synchronizationRequired for grid connection or re-connection after trip.
irradiation levelsAnti-Islanding – AI as required by standards (VDE0126, IEEE1574, etc)Grid Monitoring
Operation at unity power factor as required by standardsF t V lt /f
6868
Fast Voltage/frequency detection
Plant MonitoringDiagnostic of PV panel arrayPartial shading detection
PV systems
Grid Connected PV SystemGrid Connected PV Systemr
Pow
erS
olar
69
PV systemsResidential PV systemsResidential PV systems
r P
ower
Sol
ar
• Residential PV grid-connected systems (generally feed into the low voltage grid)
• Power rating up to 10 kW• Power rating up to 10 kWp
• The amount of the generated electricity depends on both the meteorological conditions
14-Apr- 70
A 3.15MWp Large PV Plant in SpainLarge PV Plantsr
Pow
er
(photo: http://www.solarig.com)
Sol
ar
• Large-scale, PV grid-connected systems (generally feed into the di lt id)medium voltage grid)
• Power rating from 200 kWp to many MWp (e.g. 10MWp or more)• The amount of the generated electricity depends on both the
meteorological conditions and the instantaneous grid load:meteorological conditions and the instantaneous grid load: energy rejections
14-Apr- 71
5 Summary 5. Summary
72
Summary
Renewable Energy Systems (RES) Solutions for the future – New grid infrastructure and control Increase power production close to the consumption place
s
p p p p May decrease the power capacity at the transmission level and will
make the central grid control more complex (long term, smart grid). Should be able to run grid and islanding modes
lusi
on
s g g Ancillary functions are included to improve grid stability and avoid
blackout as well as control of grid Wind Turbines and PV’s - the fastest growing technologies
Con
cl Establish now Renewable Power Plants Power Converters & Control
Need MPPT functions Medium voltage power converter technology Reliability Provide ride-through capabilities Intelligent grid connection
Grid impedance estimation Monitoring and advanced diagnosis
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Power Electronics -> Key Enabling TechnologyStill many challenges to be solved
IEEE Trans. on Power Electronics
http://mc.manuscriptcentral.com/tpel-ieee
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Some published papers in the fieldA. Luna, P. Rodriguez, R. Teodorescu, F. Blaabjerg, "Low voltage ride through strategies for SCIG
wind turbines in distributed power generation systems," Power Electronics Specialists Conference, 2008. PESC 2008. IEEE , vol., no., pp.2333-2339, 15-19 June 2008
P. Rodriguez, A. Timbus, R. Teodorescu, M. Liserre, F. Blaabjerg, "Flexible Active Power Control of Distributed Power Generation Systems During Grid Faults," Industrial Electronics, IEEE y g , ,Transactions on , vol.54, no.5, pp.2583-2592, Oct. 2007
P. Rodriguez, A. Timbus , R. Teodorescu, M. Liserre, F. Blaabjerg , "Reactive Power Control for Improving Wind Turbine System Behavior Under Grid Faults," Power Electronics, IEEE Transactions on , vol.24, no.7, pp.1798-1801, July 2009
F. Blaabjerg, R. Teodorescu, M. Liserre, A.V. Timbus,“Overview of Control and Grid Synchronization F. Blaabjerg, R. Teodorescu, M. Liserre, A.V. Timbus, Overview of Control and Grid Synchronization for Distributed Power Generation Systems, IEEE Trans. on Industrial Electronics, Vol. 53, No. 5, 2006, pp. 1398 – 1409.
S. B. Kjaer, J.K. Pedersen, F. Blaabjerg, "A review of single-phase grid-connected inverters for photovoltaic modules," Industry Applications, IEEE Transactions on , vol.41, no.5, pp. 1292-1306 Sept -Oct 20051306, Sept. Oct. 2005
T. Kerekes, R. Teodorescu, C. Klumpner, M. Sumner, D. Floricau, P. Rodriguez, "Evaluation of three-phase transformerless photovoltaic inverter topologies," Power Electronics and Applications,2007 European Conference on , vol., no., pp.1-10, 2-5 Sept. 2007
F. Blaabjerg , Z. Chen and S. B. Kjaer "Power electronics as efficient interface in dispersed powergeneration systems", IEEE Trans. Power Electron., vol. 19, pp. 2004, pp. 1184-1194.
k k h d l b C l l S l dM. P. Kazmierkowski , R. Krishnan and F. Blaabjerg Control in Power Electronics—SelectedProblems,Book,2002;AcademicPress
Z. Chen, J.M. Guerrero, F. Blaabjerg, “A Review of the State of the Art of Power Electronics for Wind Turbines” IEEE Transactions on Power Electronics, Vol. 24, No. 8, pp. 1859-1875
A. Timbus, M. Liserre, R. Teodorescu, P. Rodriguez, F. Blaabjerg, “Evaluation of Current C t ll f S t ” IEEE T ti P El t i V l 24 N 3 2009 Controllers for Systems”, IEEE Transactions on Power Electronics, Vol. 24, No. 3, 2009, pp. 654-664.
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Transformerless PV inverters with boost
DC
DC
DC
ACGridPV
Array
boost
DC ACy
•Time sharing configuration[3]
•FB inverter + boost• Typical configuration [1]
r g g [ ]
Pow
erS
olar
•High efficiency (>95%) •Efficiency > 96%
7676
High efficiency (>95%)•Leakage current problem•Safety issue
•Extra diode to bypass boost when Vpv > Vg•Boost with rectified sinus reference