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“Grid Code testing of Full Power Converter Based Wind Turbines Using back-to-back Voltage Source Converter System” EWEA 2013, Vienna Nicolás Espinoza , PhD Student, Chalmers University of Technology [email protected]. VÄRLDENS SKILLNAD . - PowerPoint PPT PresentationTRANSCRIPT
VÄRLDENS SKILLNAD
“Grid Code testing of Full Power Converter Based Wind Turbines Using back-to-back Voltage Source Converter System”
EWEA 2013, Vienna
Nicolás Espinoza, PhD Student,Chalmers University of Technology
• Introduction– Alternative approach of grid code for wind turbines– Grid code analysis regarding interconnection of wind turbines. – Simulation of existing testing setup: 4 MW FPC based WT
connected to an 8 MW back-to-back VSC system, operated as a test equipment.
– Control system for the wind turbine and test equipment are given.– Results shown the capability of the test equipment in controlling
the voltage while handling short circuit currents.– Unique opportunity of field test of wind turbine using VSC system.
“Grid Code testing of Full Power Converter Based Wind Turbines Using back-to-back Voltage Source Converter System”
Contents• Grid codes• Simulation models• Results
Reactive Power Requirements• Normal operation range.• Example:
• Strictest requirements: lagging power factor during upper limit of the normal voltage operation band.
0.850.925 0.95 0.975 1 0.975 0.95 0.925
Lagging
1
1.05
1.1
1.15
0.95
0.9
1.2
Syst
em V
olta
ge [p
u]
Power factor0.9
E.ON (Germany) [6]
Energinet.dk (Denmark) [10]
Red Eléctrica España (Spain) [8]
Leading
Active Power Curtailment • Active power output vs. system frequency
• Example:
• Different active power control requirements.• Overfrequency control in Danish grid code.
100
80
60
40
20
047 48 49 50 51 52 53
A B C
D
E
Cont
rolla
ble
WFP
S’s
Activ
e Po
wer
Out
put
(as
a %
of a
vaila
ble
activ
e po
wer
)
System electrical frequency [Hz]
0
47 48 49 50 51 52 53
P available
Act
ive
Pow
er
System electrical frequency [Hz]
P produced
P min
P delta
Control bandDead band
Droop 1
Droop 2
Droop 3
Droop 4
f min f maxf1 f2 f3 f4
Low Voltage Ride Through• Fault representation at the connection point• Example:
• Different requirements for active and reactive power.
00 1
0.3
0.4
0.5
0.6
0.2
0.1
0.7
Syst
em V
olta
ge [p
u]
Time [s]
E.ON (Germany) [6]
Energnet.dk (Denmark) [10]
Red Eléctrica España (Spain) [8]
0.8
0.9
1
2 30.50.25 0.75 1.25 1.5 1.75 2.25 2.5 2.75
Svenska Krafnät (Sweden) [11] Nordel [12]
EirGrid (Ireland) [9]
National Grid (U.K.) [7]
Contents• Grid codes• Simulation models• Results
Conventional Method• Impedance-based testing device
VSC-Based Method• Overview of simulation setup and system modeling
Test Equipment: VSC in back-to-backGrid Code
TestingCoupling
Inductor and Filters
AC Grid
G
Wind TurbineOutput
TransfomerCoupling
Inductor and Filters
Wind Turbine
GeneratorFull Power Converter
LVRT profile
V/Vn
1.0
t [s]
Coupling Inductor and
Filters
Coupling Inductor and
FiltersAC
DC AC
DC AC
DC AC
DC
V/Vn
1.0
t [s]
Voltage dip
PCC
4 MW Full Power Converter WT8 MW Converter as Test Eq.
Control Strategy for the WT model• Control overview for VSC
– Inner current control– Outer active and reactive power control – DC voltage control
*2DCv
2DCv
*P
P
*Q
du
qu
ωLDq to ABC
*,, CBAVt PWM
DCv
61Sw
S
Q
PI
PI
ωL
P
PI
Controller
*S
Current Controller
*dti
dti
*qtiqti
dsv
qsv
*dtv
*qtv
Active Power Controller
DC-Link Voltage Controller
Reactive Power Controller
• Voltage Control: full controllability of the applied voltage– Amplitude– Phase angle– Frequency
• Implementation
Control Strategy for Test Equipment
PCC Voltage Control
)(dqsv
qsdsdqs jvvv )*(
)*( dqti
Contents• Grid codes• Simulation models• Results
Danish LVRT test.
LVRT TEST. (a) Danish grid code, (b) WT output power, (c) Controlled PCC voltage, and (d) test equipment terminal current.
Time [s] 0.0 1.0 2.0 3.0 4.0 5.0 ... ... ...
0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10
Volta
ge [p
u]
LVRT profile
Time [s] 0.0 1.0 2.0 3.0 4.0 5.0 ... ... ...
-0.10
0.00
0.10
0.20
0.30
0.40
0.50
WT
Outp
ut P
ower
[pu]
VSC1 out 2
Time [s] 0.0 1.0 2.0 3.0 4.0 5.0 ... ... ...
-1.00 -0.80 -0.60 -0.40 -0.20 0.00 0.20 0.40 0.60 0.80 1.00 1.20
Volta
ge [p
u]
VSC1 out 2
Time [s] 0.0 1.0 2.0 3.0 4.0 5.0 ... ... ...
-1.00 -0.80 -0.60 -0.40 -0.20 0.00 0.20 0.40 0.60 0.80 1.00
Curre
nt [p
u]
It1 ABC
(a) (b)
(c) (d)
Danish LVRT
Controled PCC voltage Test VSC terminal current
Active Power Reactive Power
Conclusions• Comparison of different European grid codes:
– Dependencies between voltage, frequency and reactive power.– Active power curtailment strategies against frequency deviation – LVRT profiles are compared in terms of strictness and reactive
power management during the voltage dip. • Different approach of grid code testing. • Control strategies for WT and Test Eequipment. • Two representative case studies.• More reliable representation of grid.
Upcoming Activities within the SWPTC• Laboratory setup at 100 kW / 400 V. • Field test at “Big Glenn” WT, programmed for autumn 2013.• Unique opportunity: Frequency test.
Thanks for your attention
Nicolás Espinoza, PhD [email protected]
CHALMERS UNIVERSITY OF TECHNOLOGY, Gothenburg, Sweden.