Distributed Photovoltaic Generation Emulation in Converter Based Power Grid Emulation System Anthony...
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Transcript of Distributed Photovoltaic Generation Emulation in Converter Based Power Grid Emulation System Anthony...
Distributed Photovoltaic Generation Emulation in Converter Based Power
Grid Emulation System
Anthony Perez,
Mitchell Smith, Wenchao Cao, Dr. Fred WangFinal Presentation
July 17, 2014
Knoxville, Tennessee
Outline
• Objective and Approach
• Emulation Structure of HTB Converters
• Distributed Photovoltaic Model
• Future Work
Objective and Approach
1. Use one converter to emulate one PV unit.
2. Use two converters to emulate two PV units.
3. Use one converter to emulate a radial distribution line with two PV units.
Objective: To emulate a distribution feeder with two PV units
Physical components of two stage PV inverter system
One inverter with PV model
Hardware Test Bed
Two-Area System Topology
Simulations of Two-Area System
Emulation Structure of HTB Converters
Functionality:
1. Current and voltage are measured.
2. Voltage’s value goes to the PV model to generate the current reference.
3. Current’s value goes to a current control loop to generate the signals to the inerter.
Single Inverter System
Single Inverter System Control (Simulink)
Distributed PV model
Current control
Current Control Testing
Different testing have been done to test if the simulation has been well implemented.
The different testing are:
1. Id & Iq current control2. P & Q control
Active Current test
Reactive Current test
A step function was used for this test.
-For Id: a)Step time – 0.2 s b)Range – 0 to 0.5 pu
-For Iq: a)Step time – 0.2s b)Range - 0 to 0.2 pu
P & Q Control
P and Q response when a step change is apply as a reference.
For Q: Step time – 0.2 s Range - 0 to 0.1 pu
For P: Step time – 0.2 s Range – 0 to 1pu
Distributed Photovoltaic Model
Physical components of two stage PV inverter system
One inverter with PV model
Distributed PV model
PV panel model
Distributed Photovoltaic System Model (Simulink)
5-13
Sub part 1:PV panel model
Sub part 2: System control model
Sub part 1: PV Panel Model
5-14
S: solar irradiance (W/m2)T: temperature (deg C)Pmax: Maximum power outputSingle diode model
stcVopstcIsc
VocIscstcPmpP
___max
Simulation model of PV panel
Simulation of PV Panel Model
• Natural conditions variations like temperature and solar irradiance are considered in this work, to see the impacts in the system and to obtain more realistic results.
0 10 20 30 40 500
2
4
6I - V curve with irradiance changes (T = 25 C)
Voltage (V)
Cu
rre
nt (
Am
ps)
S = 600 W/m2
S = 800 W/m2
S = 1000 W/m2
0 10 20 30 40 500
2
4
6
Voltage (V)
Cu
rre
nt (
Am
ps)
I - V curve for temperature variations (S = 1000 W/m2)
T = 25 C
T = 45 C
T = 60 C
0.2 0.4 0.6 0.8 1 1.225
30
35
Time (s)
T (
C)
0.2 0.4 0.6 0.8 1 1.2600
800
1000
Time (s)
S (
W/m
2 )
0.2 0.4 0.6 0.8 1 1.20
0.5
1
Time (s)
Po
we
r (p
u)
Pmax
Q
Sub part 2: DPVS Control Model
Ref. http://www.powerworld.com/files/WECC-Solar-PV-Dynamic-Model-Specification-September-2012.pdf [Western Electricity Coordinating Council]
Q-V droop control
P-f droop control
DPVS Control Model (Simulink)
P-f droop control
Q-V droop control
P & Freq. Droop
-A ramp function was used for this test.
-For freq: slope – 0.5 a)starting time – 0 b)initial output - 60
- Dead-band: 0.05 Hz
Note: The frequency of the constant source is modify to have an step change of 0.3 in 0.5 and 0. 8 s.
0 0.2 0.4 0.6 0.8 1-0.5
00.5
11.5
Time (s)Act
ive
Po
we
r (p
u)
0 0.2 0.4 0.6 0.8 160
60.260.460.660.8
Time (s)
Fre
qu
en
cy (
Hz)
Q & V Droop
-A ramp function was used for this test.
-For freq: slope – 0.2 a)starting time – 0 b)initial output – 0.9
- Dead-band: 0.02 pu
Note: The amplitude of the constant source is modify to change from 1 to 1.1 and 0.9 pu in 0, 0.5 and 0. 8 s respectively.
0 0.2 0.4 0.6 0.8 1-0.3-0.2-0.1
00.10.20.3
Time (s)
Re
act
ive
Po
we
r (p
u)
0 0.2 0.4 0.6 0.8 10.80.9
11.11.2
Time (s)
Vo
ltag
e (
pu
)
System Response with Q & V and P & f Implementation
Reactive Power and terminal voltage waves when the voltage change from 1 to 1.1 pu in 0.5 seconds and to 0.9 pu in 0.8 seconds.
0.1 0.3 0.5 0.7 0.9 1.1 1.2-0.5-0.3-0.10.10.30.5
Time (s)
Q (
pu
)
0.2 0.4 0.6 0.8 1 1.21.20
0.5
1
1.5
Time (s)
Vo
ltag
e (
pu
)
0 0.2 0.4 0.6 0.8 1 1.2
0.2
0.4
0.6
0.8
Time (s)P
(p
u)
0 0.2 0.4 0.6 0.8 1 1.2
60
60.1
60.2
Time (s)
Fre
qu
en
cy (
Hz)
Active power and frequency Waveforms when the frequency it is changed by .3 Hz in .5 and .8 second respectively
Two PV Unit System SimulationA distribution feeder with two PV units
PV 1
PV 2
Two PV Inverter System Simulation
0.2 0.4 0.6 0.8 1 1.20.9
0.95
1
Time (s)
V (
pu
)
0.2 0.4 0.6 0.8 1 1.2
0
1
2
3
x 104
P (
W)
Q(V
ar)
Time (s)0.2 0.4 0.6 0.8 1 1.2
0
1
2
3
x 104
Time (s)
P (
W)
Q(V
ar)
0.2 0.4 0.6 0.8 1 1.2
0.96
0.98
1
1.02
Time (s)
V (
pu
)
To verify the effects of the droop function implementation into the two PV models, it is shown in the graphs below. The reactive power and terminal voltage changes at the terminal of each PV system.
Without Q-V droop With Q-V droop
Q1, Q2
P1, P2
V1
V2
Q1, Q2
V1
V2
P1, P2
Conclusions & Future Work
• A converter based distributed PV emulator with variable irradiance and temperature is designed.
• Different control strategies for the DPVS were implemented in order to maintain the balance in the power grid.
• The implementation of this system into the real HTB configuration is required for future work.
Questions?