Download Why DC Microgrid?

DC/DC
DC/AC
DC/AC
Why DC Microgrid?
• Less number of conversion
• No problem in voltage
harmonics and reactive power
• High quality of voltage for
sensitive dc loads
Voltage and Stabilization Signals
DC Test System
DC/AC
DC BUS
AC/DC
AC BUS
A New Distributed Controller for DC Microgrids
Stability Enhancement
Permanent Magnet
Synchronous
Generator
DC/AC
DC to DC
converter,
A buck for the
DC Resistive
load
AC to DC
converter
DC/DC
Community Microgrid of UWM
DC to DC
converter,
A buck for the
supercapacitor
Everything is modeled as a current source
dependent on voltage (constant power).
Simplification
Main grid is considered as voltage source without
converter.
Stability of DC Microgrids
• Constant Power Loads (CPL) can endanger DC microgrid stability.
• An example of CPL: Tightly regulated converters of electric drives
Traditional Lyapanov Equations
controller
State Feedback Controller for The Simplified System
Our Proposed
Controller
𝑋 = 𝐴𝑋 𝑡 + 𝐵𝑈 𝑡
X  t   i1  i1  0  i2  i2  0  i3  i3  0  ie  ie (0) vcn  vcn (0) vc1  vc1 (0) vc 2  vc 2 (0) vc 3  vc 3 (0) 
 r1  rc1  rcn

L1


r
 cn

L2


r

 cn

L3

rcn


Le
A

1


Cn


1

C1



0



0

Literature Review
r
 cn
L1

r2  rc 2  rcn
L2

rcn
L3
rcn
Le
rcn
L1
1
L1
1

L1
rcn
L2
rcn
L2
1
L2
0
r3  rc3  rcn
rcn
L3
1
L3
0
0
1
Le
0
0


L3
rcn
Le

rcn  re
Le

0

1
L2
1
Cn
1
Cn
0
0
0
0
0
0
0
0
0
1
C2
0
0
0
0
0
0
1
Csc
0
0
0
0

1
Cn
r
 cn
L1


0 


0 


1
 
L3 

0 



0 


0 


0 


0 


 rc1


 0


 0


 0
B t   

 0

 1

 C1

 0


 0

0
rc 2
0
0
0
0
1

C2
0

0 


0 


rsc 
 P1 (t )  P1, stab (t ) P1 (0) 




V
(
t
)
V
(0)

1
1


0 


 U t  P2 (t )  P2, stab (t )  P2 (0)
 


V
(
t
)
V
(0)
2
2


0 
 P (t )  P

Psc (0) 
sc
sc , stab (t )




0 
Vsc (t )
Vsc (0) 



0 

1 
 
C2 
• Active Damping
• Virtual Impedance
Large Signal
Stability
Small Signal
Stability
Controller Design
U  t   KX
• Central Controllers
• Multi Agent Controllers
The Resulting Distributed Control
The feedback system can guarantee microgrid
stability only if the interaction between all
elements are modeled
Switching
Effects
Converter
Controllers
DC circuit
breakers
This shows the idea of
distributed control.
None of these
controllers have access
to other controller
measurements.
U(t) is designed to make the system stable and linear and provides the best
solution for minimizing an objective function.
Less
contribution
from the
loads
the least
possible
disturbance
in all system
signals
Objective
Function
Optimization with the constraint of distributed
control
Author: Marzieh Karami
AC to DC
interface
controller
State-space Average Model: Converter Modeling
The Resulting K
0
0
0 0 0.0560 0
0.1207

K   0 0.5726
0
0 0 0 0.1217
 0
0
0.0002 0 0 0
0
Total
microgrid
spate
space
linear
equations
This makes
the
0 whole

system stable
with
0 the least
extra power

0.0004
injection
signals.
Supervisor: Rob Cuzner
https://uwm.edu/engineering/people/cuzner-ph-d-robert/
Further work
Solve the optimization for accurate model
Implement the controller in the community microgrid of UWM
Apply the concept to AC microgrids
Questions? Email: [email protected]