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Power Electronics in New and Renewable Energy Systems. Mohammad A. Abusara Lecturer in control and Power Electronics Renewable Energy Research Group College of Engineering, Mathematics, and Physical Sciences. Outline. Microgrid Grid Connected Interleaved Inverter - PowerPoint PPT Presentation
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Power Electronics in New and Renewable Energy Systems
Mohammad A. Abusara Lecturer in control and Power ElectronicsRenewable Energy Research GroupCollege of Engineering, Mathematics, and Physical Sciences
Outline
Microgrid
Grid Connected Interleaved Inverter
Exhaust Heat Energy Recovery Systems
Marine Renewable Energy
Microgrid System
Microgrid System
Transformer
Critical loads
Non-critical loads
Main switch
SwitchDG
Grid
Buck IGBT
Boost IGBT
Buck mode
Boost mode
Bidirectional DC/DC converterDclink
Boost IGBT
35kWHr lithium-ion batteries (60kVA Inverter)
100kW micro Gas Turbine
MicroGrid: Controller Structure
Droop Controller
Voltage Controller
Battery Management
Power Measurement
Virtual L
Buck IGBT
Boost IGBT
Buck mode
Boost mode
Bidirectional DC/DC converter
Dc-Link Voltage
Controller
P
* 0P
* 0P
*P
nP
nQ
*Q
Charging
Discharging
Grid
Island
++ +
--
- refV
Q
*dclinkV
dclinkV
Charging/Dischaging
Grid/Island
Microgrid Challenges and Features
Challenges• Maintain stability during connection, disconnection, load application/shedding
• Good Load sharing in island mode
• Good current quality in grid-connected mode
Features• Seamless transfer from grid-connected mode to island mode and vice versa
• Improved current quality
• Improved transient response
Microgrid-Practical Test
Battery
Power Electronics
Microgrid-Practical Results
Transformer
Critical loads
Non-critical loads
Main switch
SwitchDG
Grid
Microgrid-Practical Results
The effect of virtual impedance on improving current THD
Grid Connected Interleaved Inverter
Interleaved Concept
One channel is replaced by a number of channels connected in parallel
Switching instants are phase shifted equally over a switching period
Introduced for telecommunication power supplies (low voltage high current)
Interleaved Inverter- Advantages
Smaller Power Switches
Smaller capacitors
Smaller Inductor
Novel DC/AC Grid Connected Interleaved Inverter
LuL
C
auV
cuV
buV
R
uL
uL
C
R
C
R
LI
L
L
dcV
1LI
OutIGV
1inVAdvantages over 2-level topology
Smaller C and hence so high output impedance to voltage harmonics (better current THD)
No need for a second L
Smaller in size
Controller Structure
)(zK
sL1
*1L
I
1LI
*2LI
CsRCs 1
sLu
1
uV
OutIcV
cV
LI
fV
PWM 1inV
1ModV
Controller
ZOH
ZOH sTde
2ModV
NModVNin
V
)( zK
cVfV
PWM
ZOH sTde
2LI
*NL
I
cV
PWM
ZOH sTde
NLI
sL1
sL11
N
2inV
)( zK
*OutI
fV
System Modelling
ZOH )( zK
*xLI
sTde
LI
)(sB
NxLI
uV
xinV
)(sA
( )fV z
2
3 21
( )( ) ( )u
u u u
L Cs RCsA s
LL Cs RC L NL s L NL s
1( ) ( )s
d
T sT seG z Z e A s
s
Passive Damping
• For active damping
• Sampling frequency (35kHz) is only 1.47 to 3.2 times the natural resonance frequency
• Passive damping is possible (small capacitor current thanks to interleaved topology)
ds ff 8
Passive Damping R
Root locus, R = 0 ohm -1.5
-1
-0.5
0
0.5
1
1.5
-1.5 -1 -0.5 0 0.5 1 1.5
-1.50
-1.00
-0.50
0.00
0.50
1.00
1.50
-1.5 -1 -0.5 0 0.5 1 1.5
20uL H
Root locus, R = 0.5 ohm
The varying parameter in the Root Locus is the grid impedance
Controller Design
Frequency (Hz)
uLIncreasing
uLIncreasing
Unstable or critically stable
Frequency (Hz)
uLIncreasing
Stable
uLIncreasing
0.5 0.35( ) 100.97
zK zz
Phase Lag Controller
Proportional ControllerK(z) =10
Robust Digital Controller
Immunity to Grid Impedance VariationsExcellent Current Quality (THD=2.3%)
-1.50
-1.00
-0.50
0.00
0.50
1.00
1.50
-1.5 -1 -0.5 0 0.5 1 1.5
1000uL H
Interleaved Grid Connected Inverter
Exhaust Heat Energy Recovery Systems
Energy Recovery SystemAlthough it is a dominantprime mover and one of themost efficient powersources, a typical modernturbocharged Diesel enginestill wastes significantamounts of fuel energy.
The exhaust waste heat energy can be recovered and converted into useful electrical power
Components of Exhaust Recovery System
• Fuel Saving 5-7%• Power Boost 10-15%
Turbine + High speed alternator Power Electronics
Exhaust Energy Recovery
Organic Rankin Cycle (ORC) System
ORC System Diagram
ORC Optimisation
CustomersOn road trucks Off road vehicle Stationary power plants
Hybrid Turbocharger
Power Electronics
TurbineCompPM Machine+
-
Motoring
Generating
Controlled DC
Marine Renewable Energy
Marine Renewable Energy Systems
Wave Tide
Thank You