Yusi Liu, H. Alan Mantooth, Juan Carlos Balda V MVCB4 ... · Yusi Liu, H. Alan Mantooth, Juan...
Transcript of Yusi Liu, H. Alan Mantooth, Juan Carlos Balda V MVCB4 ... · Yusi Liu, H. Alan Mantooth, Juan...
Future Hybrid MicrogridsYusi Liu, H. Alan Mantooth, Juan Carlos Balda
Department of Electrical Engineering
University of Arkansas
Hybrid Microgrid Concept and Test Bed at NCREPT
GRAPES Confidential
Proposing A New Start-Up Procedure of AC-DC Converter
Microgrids
Integrates distributed generation
and energy storage
Smart controls
Increased reliability
More resilient system
Faster dynamic response
1 MVA Prototype Validation
High Current Variable-Value AC Filter Inductor
Analysis of general reasons behind the inrush
current during ac-dc converter start-up
procedure
Simple open-loop duty cycle control as a dc-dc
boost converter
All IGBTs are enabled after saturation period
Optimal design of ramp time considering the dc
capacitor value
Validation on a 1-MVA ac-dc rectifier prototype
– Inrush current during duty-cycle soft-start is
less than 25 A
Recent publication:
Y. Liu, C. Farnell, H. A. Mantooth, J. C. Balda, "Realization of High-Current Variable AC Filter
Inductor Using 6.5% Silicon Iron Powder Magnetic Core," in Proc. Applied Power Electronics
Conference and Exposition (APEC), Tampa, FL, March 2017.
Design of 6.5% Si-Fe powder core, µe0=60,
N=24, L = 300 µH @ 0A, 100 µH @ 2000A
24 e e
e
A NL
l
AC Distribution Substation
13.8 kV AC
Non-critical load CHPCritical load
=~ =~ =~
Electric carcharger
Fuel cell(DG)
Solar & windPower (DG)
Li-ion batterystation
=~
PCC
Utility Input
12.47kV – 480VUTCB1
480VMSB1
LVB1
LVCB4
480V
MVCB3
4.16/13.8 kVMVB2
VVVF
T6
MVB1
LVCB5 LVCB6
LVCB9
LVCB18
LVCB12 LVCB13 LVCB14
MVCB2 MVCB1
MVCB5MVCB4 MVCB6
MVCB8 MVCB9 MVCB10
LVCB16
T1 T2 T3
T5
MVCB12
LVCB8
LVCB15
T4
MVCB13
MV microgrid
LV microgrid
~=~
MVCB13
LVCB7
~=~
~
=
~
LVCB3
LVCB10
4.16/13.8 kV
Regen 1 Regen 2
UT
Microgrid
LVCB11
LB
NCREPT as a microgrid test bed
for verifying converter design
and control algorithms of
commercial-scale high-power
ac-dc converters in:
Grid-connected mode
Islanded mode
VDC
Lac
VDC
Lac
480-V duty-cycle soft-start experimental results
Compare four feasible magnetic core solutions
Variable inductor reduces the current ripple at low current
(a) Traditional silicon steel three-phase one-core. (b) Powder material three-phase
one-core.
(c) Powder material single-phase core. (d) Hybrid three-phase one-core (silicon
steel + powder material )
Solution Material
volume
Core
loss
Structure
complex
Unbalance
current
Size fit into
cabinet
Fringing
effect
Variable
inductance
(a) + -- ++ - + -- --
(b) ++ ++ --- - -- + +
(c) - + + + ++ ++ +
(d) ++ - -- - + + -
Cdc
Rb
L1
RSS
Lg
FU
Cf
Rcf
EMI filter
MOV
iabc2 iabc1Soft-start relay
Sap
San
Sbp
Sbn
Scp
Scn
DS vabc
CB
To MV
Microgrid
480 V
T
vPWM
vabc1 To DG load/
source, dc-dc
converter, dc
microgrid
Start
Is Cdc voltage satisfy
β ∙ Vdc* < Vdc < γ ∙ Vdc
*
?
Voltage
error
No
Is Vdc > α1∙ Vdc*?
Duty-cycle control
Disable upper switches
Increase duty-
cycle Tss*
No
Yes
Yes
Complimentary operation
enables
Is VSS_dc* = Vdc
*?
Yes
Increase ramp
reference VSS_dc*
No
Steady state480-V resistor-relay-bypass
experimental results
500 A 1000 A 1800 A
MATLAB-PLECSTM simulation allows
to model variable magnetic material
480-V grid connect mode hardware
test @ 200 kVA
Preliminary 300-V islanded mode
hardware test @ 100 kVA (future work
will increase ac input voltage and
improve current THD)
Vdc = 760 V
vac = 480 V
Vdc = 670 V
vac = 480 V
Vdc = 760 V
vac = 483 V
ia1 = 220 A
ib1 = 220 A
Vdc = 760 V
vac = 310 V
ia1 = 100 A
ib1 =100 A
Grid-connected mode
Islanded mode
Converter-side current
Converter-side current
Vdc
Id*
abc
dq
iabc1-
+
-
ωL/Zb
ωL/Zb
ed
abc
dq
vabc
eq
PLLΘ
ePWM
Sd*
Sq*
S1~6
Θ
Iq*
Id
Iq+-
PIiq
-+
+
+- PIid
Hv
Hi
Hv
÷
+- PIv
Vdc*
vd
vq
SV
GEN
DCSS
GEN
Soft Start
Selector
ta*
tb*
tc*
Tss*
tA*
tB*
tC*
SAT
vab
ia1
Vdc
ib1
t0 t1 t2
t0 t1
vab
ia1
Vdc
ib1