Eco-Damper - ICD damper, ICC Check valve and ICS control valve
Active Damper for Power Electronics Based Systems · HARMONY SYMPOSIUM – HAOFENG BAI 14...
Transcript of Active Damper for Power Electronics Based Systems · HARMONY SYMPOSIUM – HAOFENG BAI 14...
H a o f e n g B a i , P h . D s t u d e n tD e p a r t m e n t o f E n e r g y T e c h n o l o g y
h b a @ e t . a a u . d k
Active Damper for Power Electronics Based Systems
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 2
Outline
Background
Concept: Damping Resistance
Realization of the Active damper
Experimental Results
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 3
Background
Background
Concept: Damping Resistance
Realization of the Active damper
Experimental Results
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 4
Background
Power-Electronics Converters
• Grid impedance
• LCL filters of the grid-connected converters
• Limited control bandwidth in high power applications
Harmonic resonance and instability !!![1]. Mollerstedt, E.; Bernhardsson, B., "Out of control because of harmonics-an analysis of the harmonic response of an inverter locomotive," Control Systems, IEEE , vol.20, no.4, pp.70,81, Aug. 2000
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 5
Background
Explanation
− Impedance-based Model of Grid Connected Converter
gi
ocY PCCV
LZ
sV*g cli G
gi
PCCV sV*g cli G
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 6
Background
Explanation
− Nyquist based stabil i ty analysis
-50
0
103
-90-45
04590
135
(Hz)
YocYL
-1 -0.5 0 0.5 1
-1
-0.5
0
0.5
1Stiff grid
-60
-40
-20
0
103
-90-45
04590
135
(Hz)
YocYL
-1 -0.5 0 0.5 1
-1
-0.5
0
0.5
1
Weak grid
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 7
Background
Existing Solutions
− Passive damping• High power loss;• Sensi t ive to parameter changing.
− Active damping• Within the control loop of converter;• Limited by the control bandwidth.
Other possibil i t ies?
Active damper
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 8
Concept: Damping Resistance
Background
Concept: Damping Resistance
Realization of the Active damper
Experimental Results
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 9
Concept: Damping Resistance
System with Active Damper
ocY PCCV SVINVi SL SR
1
daR*INV cli G
3 ,max
1sfoc
da
YR
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 1 0
Concept: Damping Resistance
System with Active Damper
-30
-20
-10
0
103
-90-45
04590
135
Yocm1YL
Frequency (Hz)
Phi (
degr
ee)
Mag
(dB
)
-2 -1 0 1 2
-2
-1
0
1
2
imag
inar
y ax
is
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 1 1
Realization of the Active damper
Background
Concept: Damping Resistance
Realization of the Active damper
Experimental Results
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 1 2
Realization of the Active damper
Topology
Fundamental voltage of the grid can be sustained by the series LC filter, which brings the following benefits:
• Low power rating;
• Low dc-link voltage;
• High switching frequency.
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 1 3
Realization of the Active damper
Control strategy
11
aa
L s C s
__
ia dcpa dc
KK
s
*ahi
*dcaV
1.5 saT se
Composed of two parts:
• Dc-link voltage control loop
• Harmonic current control loop
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 1 4
Realization of the Active damper
Control strategy
11
aa
L s C s
__
ia dcpa dc
KK
s
*ahi
*dcaV
1.5 saT se
DC-link voltage control loop:
• Carried out at q-axis at the fundamental frequency.
• The output of the PI controller are directly fed to the PWM modulation block.
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 1 5
Realization of the Active damper
Control strategy
11
aa
L s C s
__
ia dcpa dc
KK
s
*ahi
*dcaV
1.5 saT se
Harmonic current control loop:
• Responsible for mimic the damping resistance;
• Decoupled with the dc-link voltage control loop through a harmonic extraction block.
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 1 6
Realization of the Active damper
Impedance model of the active damper
Structurally, the active damper is no different from a grid-tied converter, except with a lower rating and the series LC filter as the controlled plant.
ocaY PCCV
sZ
SVPCCh
clada
V GR vaY
The usual current source in the Norton circuit is replaced by an admittance Yva
1va cla
da
Y GR
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 1 7
Realization of the Active damper
A special problem for the active damper
Yva will be non-passive above the bandwidth of the active damper, introducing new possibility for harmonic resonance at higher frequencies with grid capacitance (above the control bandwidth of the active damper).
2ocm va oca oc da oc
grid converteractive damper
Y Y Y Y Y Y
21
L pS S
Y sCL s R
-80-60-40-20
020
()
103
-135-90-45
04590
Yocm2YL2M
ag (d
B)
Phi (
degr
ee)
-1000 -500 0-100
-50
0
50
100
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 1 8
Slightly higher than the upper limit of the non-passive region of the grid converter.
Realization of the Active damper
A special problem for the active damper
Solution:A simple first order low-pass filter.
, 2clpf c c
c
G fs
Design of the low-pass filter• The purpose is to avoid deteriorating damping effect
intended for the grid converter over its non-passive range.• Reducing the non-perfection of the current control loop of
the active damper.
1kHzcf
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 1 9
Realization of the Active damper
Modified harmonic current control loop
11
aa
L s C s1.5 saT se
*ahi
c
cs
31
ocm lpf cla oca ocda grid converter
active damper
Y G G Y YR
-80-60-40-20
020
103
-90-45
04590
Phi (
degr
ee)
Mag
(dB
)
0
-10 -5 0-0.1
-0.05
0
0.05
0.1
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 2 0
Experimental Results
Background
Concept: Damping Resistance
Realization of the Active damper
Experimental Results
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 2 1
Experimental Results
Stabil i ty analysis of the grid converter
Stiff grid
Weak grid
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 2 2
Performance of the active damper
Steady state
Startup process
Experimental Results
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 2 3
Effect of the low-pass filter
Without low-pass filter
Experimental Results
H A R M O N Y S Y M P O S I U M – H A O F E N G B A I 2 4
Effect of the low-pass filter
With low-pass filter
Experimental Results
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“ THE HIDDEN HARMONY IS BETTER THAN THE OBVIOUS ”
- P . P ICASSO
Thank You! Questions?