Empc 8-110329 a[1]
Transcript of Empc 8-110329 a[1]
Electric Machines and the Power ConversionsElectric Machines and the Power Conversions for Renewable Systems
Dc Grid Connections
Jung-Ik HaAssistant ProfessorSchool of Electrical EngineeringSchool of Electrical EngineeringSeoul National University
Background
Renewable Energy System and Grid Connections
– Considerations
• Energy Flow
– (Negative) Unidirectional
– Bidirectional
• Safety: Grounding
Non Isolation– Non-Isolation
– Isolation
• Regulation: Filteringegu at o : te g
– EMI
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Grid Connected Buck Converter
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Buck Converter
Basic Form
– Uni-Directional DC LOAD
– Bi-directional
• Synchronous Rectification
Operation StatesOperation States
– On: Charging
– Off: Fly-wheelingy g
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Power Delivery Grid Connection
– Power Delivery
Power Control
– Voltage Control Mode
V (Vflt ) Vd• Vo ↔ (Vflt ↔) Vdc
• Voltage Source ↔ Voltage Source
– No Current LimitNo Current Limit
. Converter : Cout
. Filter : Cflt, Lfltflt flt
. Line : Rline, Cline, Lline1, Lline2
– Disturbance
Power Circulation
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Power Delivery Grid Connection
– Object: Power Delivery
In Renewable System
– Power Control
C t C t l• Current Control
– Transmission Line
– Additional FilteringAdditional Filtering
– RES Model Considerations
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Power Control Current Based Power Control
ogav VPI /** I
g
dtdILVV L
oi DCRESrViV oV
– Averaged Assumption in T
DT
1 ir vsfv i
DT
ir DVdtvT
V 01
di Rdi 1dtdiLRiVV or or VV
Li
LR
dtdi
1
A or VVBAxx
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Power Control Current Based Power Control
– Closed LoopI
• Assumptions
: ∆Vo= ∆Vi=0 @t=0~T
Output Feedforward• Output Feedforward
: Vff=Vo
or VVBAxx
iRdi 1 iG 1
rvL
iLdt
RLsvG
rp
• PI Control
sKKG i
pc s
KsKG ip
c
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Power Control Current Based Power Control
– Closed Loop
• PI Control
– Pole-Zero Cancellation
K RK p RLsLsK
G pc
K
LK p
i
LsK
G po
LKLsKi
c
c
p
p
p
p
sLKsLK
LsKLsK
ii
1*
swc *5/1 : Decoupling of Discrete System
Ttvv 0@01
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Ttvv oi ..0@0,1
Power Control Vin Consideration
– Anti-windup
• Integration Problem
: Vo* Saturated Fast Recovery
VPI /** dcVPI /**
LIIe *
ino DVVu *
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Power Control Vin Consideration Li i d I Vin Consideration
– Anti-windup• Limited Integrator
• Limited Integrator
– High Feedback Gain
– Uin = Limit + Kp*eg
– Hard Limit Imposed
• Tracking Anti-windup • Tracking Anti-windup
– with unrestricted control signal
– Recursive Problem
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Power Control Vin Consideration
– Anti-windup
• Tracking Anti-windup
– Back Calculation
One Step Delay– One-Step Delay
Ks = 1/Kp
(multiplied by 1/3~3)(multiplied by 1/3 3)
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Transmission Line Line Consideration
: Ideal Voltage Source Case
– Model
– Original
– Exact Model ILine +ΔILine
• Check Point: ΔILine
• On State
• Off State
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Transmission Line Line Consideration
– Approximated Model
1 lineI designedVo :
ttriVV rpo
Line DropsLR
Vi o
LjR
Vi o
Line Drop
– Delivered Power Offset, Losses
• Approximated Modelpp
– R Loss: Pr = R*I^2
– G Loss: Pg = G*V^2
• Line Loss Compensation Required
P = P1 + Pr + Pg
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Current Harmonics Control Conducted EMI
– AC Case
• 2~40th Order Harmonics Limits: Differential Mode
– IEC61000-3-2,12, IEEE519
150kHz(450kHz) 30MHz: Differential and Common Modes• 150kHz(450kHz)~30MHz: Differential and Common Modes
– CISPR 22(FCC)
– DC CaseDC Case
• No Regulation Currently.
• Standards for Vehicles, Ships, and Others in the Restricted Grids
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Current Harmonics Control Countermeasure: Reduction of Conducted EMI
– Lower Voltage Ripples
• C: Higher Co, Lower ESR
• L: Higher Lc, Lower R
Higher Switching Frequency• Higher Switching Frequency
– Additional Filter(s)
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RES Model Renewable Energy System Model
– Voltage Source
• Same
– Power Source
Control ObjectVDCVoVinIs
Vr
• Control Object
– Vin Vi*
.Ex) Dual Stage Cascade Control.Ex) Dual Stage Cascade Control
– Exact Models
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RES Model Dual Stage Cascade Control
– Inner Loop: Current Control
• Model
Feedforward
dtdiLRiVV or
• Feedforward
off VV uffr VVV dtdiLRiVu
sLRVi
u
1
iiGcVu * iisLR
Gci
*
GcsLR
Gc
ii *
Gci*
• Pole-Zero Cancellation
sLR sLR
Gci
1 GcsLRi *
KK
sLRsLK
Gc p K
s
LK
KsLK
ii
p
p
p
p
1* L
K pc
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Ls
sL1
RES Model Dual Stage Cascade Control
– Outer Loop: Voltage Control
dVC 2• Model
Feedforward: Pin
oininin PP
dtdVC
2
2ff PP • Feedforward: Pin
• IP Control
inff PP
o
ininin
iinp V
PVVs
KVKi
**
o
inin
iinpo
inin VVs
KVKVdt
dVC *2
2 oininin
iinpo ViPVV
sKVKV **
• Bias Point Details
– Taylor 1st: 020
2 2 inininin VVVV
inin
iinpoinin VV
sKVKVsVC *
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RES Model Dual Stage Cascade Control
– Outer Loop: Voltage Control
• Transfer Function
20ii
io
i VCKV
V
• Gains
22
00
2
0* 2 nn
n
inin
io
inin
po
inin
in
in
ssVCKVs
VCKV
s
VCVV
Gains
o
ininnp V
VCK*
2o
ininni V
VCK*
2
• Bandwidths
21
24421 242 BW 24421 242 nBW
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EMI Measurement LISN: Line Impedance Stabilization Network
– Configuration
– ExampleExample
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EMI Measurement LISN: Line Impedance Stabilization Network
– Measurement Gain
Common and Differential Modes– Common and Differential Modes
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HW5 Grid Buck Converter Design : Due to 4/7 Consider the Converter Designed in HW4
You can change parameters in order to improve the performance.
1) Using Power Source Model Design Controller1) Using Power Source Model, Design Controller. Line Inductance=50uH, Cap=0, R=0, G=inf,
2) Discuss about the Step Response: Vin* = 100V, Pin=90 step(t1) +10 W, Compare the results with/without the Feed forward Control.
3) Discuss about the Steady-State performance: Vin* = 100V, Pin=100W4) Vin* = 100V, Pin=100W) ,
A. FFT of Current Ripples @150k~30MHz?B. Adjust Co to reduce the peak harmonic component to 1/2.C D i d I t Filt ith t Adj ti C t d th kC. Design and Insert Filter without Adjusting Co to reduce the peak
harmonic component to 1/2. (option)5) FFT of the Differential Mode Current in the LISN @150k~30MHz, Vin*
= 100V, Pin=100W? Neglect Line Impedance.
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