operation of offshore wind power plants connected with hvdc · 2015-02-11 · operation of offshore...
TRANSCRIPT
O. Gomis-Bellmunt (IREC / CITCEA-UPC)
with support from M. de-Prada, A. Egea, J.L. Dominguez, E. Prieto, J. Sau, F. Diaz and M. Aragüés
Operation of offshore wind power plants connected with HVDC
Trondheim, February 2015
Agenda
• Context. Offshore wind power plants connected with VSC-HVDC.
• Functional requirements for offshore WPP connected with VSC-HVDC.
• Coordinated control for power reduction. • Conclusions.
2 Operation of offshore wind power plants connected with HVDC, O.Gomis
• Context. Offshore wind power plants connected with VSC-HVDC.
• Functional requirements for offshore WPP connected with VSC-HVDC.
• Example of coordinated control for power reduction.
• Conclusions.
3 Operation of offshore wind power plants connected with HVDC, O.Gomis
G
LV 50 Hz
MV 50 Hz
G
LV 50 Hz Other WTs Main grid
Fix Speed onshore WPP
Energy capture Fault ride-through Grid support
Main grid HV 50 Hz
G LV VF
LV dc
LV 50 Hz
MV 50 Hz
G LV VF
LV dc
LV 50 Hz Other WTs HV 50 Hz
HVAC Offhore WPP
HVAC cable
HVAC cable Compensation required Long cables (>50-80 km) not possible
G LV VF
LV dc
LV 50 Hz
MV 50 Hz Other WTs Main grid
Variable Speed onshore WPP
LV VF
LV 50 Hz
G
G LV VF
LV dc
LV 50 Hz
MV 50 Hz
G LV VF
LV dc
Other WTs
VSC-HVDC, Offhore WPP Main grid HV 50 Hz
HVDC cable
HV 50 Hz
Same WT DC cables VSC-HVDC technology
Bard Offshore 1 (BorWin 1) 400 MW First offshore WPP with VSC-HVDC First WT in 2010 To be completed in 2013
4 Operation of offshore wind power plants connected with HVDC, O.Gomis
G LV VF
LV dc
LV 50 Hz
MV 50 Hz
G LV VF
LV dc
Other WTs
Multiterminal VSC-HVDC
AC grid HV 50 Hz
Multiterminal HVDC system
HV 50 Hz
G LV VF
LV dc
LV 50 Hz
MV 50 Hz
G LV VF
LV dc
Other WTs
AC grid HV 50 Hz
HV 50 Hz
5 Operation of offshore wind power plants connected with HVDC, O.Gomis
G LV VF
LV dc
LV 50 Hz
MV 50 Hz
G LV VF
LV dc
Other WTs
VSC-HVDC grid
AC grid HV 50 Hz
HVDC grid
HV 50 Hz
G LV VF
LV dc
LV 50 Hz
MV 50 Hz
G LV VF
LV dc
Other WTs
AC grid HV 50 Hz
HV 50 Hz
6 Operation of offshore wind power plants connected with HVDC, O.Gomis
G LV VF
LV dc
LV
MV
G LV VF
LV dc
Other WTs
Point to point VSC-HVDC with an offshore AC hub
AC grid HV 50 Hz
Point to point HVDC
HV
G LV VF
LV dc
LV
MV
G LV VF
LV dc
Other WTs
AC grid HV 50 Hz
HV
Point to point HVDC
AC hub
Mainstream Renewable Power
AC cable
7 Operation of offshore wind power plants connected with HVDC, O.Gomis
HVDC technology concepts for future transmission systems for
offshore wind • Point to point HVDC • Multiterminal HVDC • HVDC grid • Offshore AC hubs • AC systems with HVDC links • All the previous combined
8
Germany Takes the Lead in HVDC, IEEE Spectrum 2013
Friends of the Supergrid
Siemens
Operation of offshore wind power plants connected with HVDC, O.Gomis
WPP concepts
– AC WPP standard/non-standard frequency
– AC WPP variable frequency
– DC WPP
– Hybrid DC-AC
9
Cost? Efficiency? Reliability? Availability? Maintainability?
http://www.bard-offshore.de/en
Operation of offshore wind power plants connected with HVDC, O.Gomis
AC collection
AC Export cable AC
DC
HVDC transmission
Offshore Platforms
AC
DC
DC
AC
10
Mikel de-Prada et al. “Analysis of DC Collector Grid for OWPP” 12th Wind Integration Workshop, London, October 2013
• WPP AC voltage ratings ↑↑ 33 kV → 66 kV?
• 50/60 Hz? non-standard frequency? Variable frequency?
• Normally with Type 3 (DFIG) and Type 4 (FPC) Wind Turbines
Operation of offshore wind power plants connected with HVDC, O.Gomis
~=
~=
Cluster 1
Export Cable
ConverterTx
ON
SH
OR
E
OFFS
HO
RE
Rectifier Inverter
AC Grid Onshore
To WTGs
Substation Offshore Wind Farm 1
Substation Offshore Wind Farm 2
Cluster 2
Converter Station
Grid Connection System
String 1
String 2
Em
ergency P
ower
Cigré WG B4-55 HVDC connection of offshore wind power plants (under development)
11 Operation of offshore wind power plants connected with HVDC, O.Gomis
Projects (WPP with VSC-HVDC) with AC collection 50 Hz
12
Borwin 1 (Transpower offshore, 2009, +/- 150 kV, 400 MW,125+75 km) for BARD Offshore 1 - 2x1 km DolWin 1 (TenneT, 2013, +/- 320 kV, 800 MW, 75+90 km) for Meg Offshore 1 - 2x13 km and Borkum West II - 2x7.5 km DolWin 2 (TenneT, 2015, +/- 320 kV, 900 MW, 45+90 km) for Gode Wind I - 7 km and Gode Wind II - 12 km Borwin 2 (Transpower offshore, 2014, +/- 300 kV, 800 MW,125+75 km) for Veja Mate – 2x10 km and GlobalTech 1 – 2x30 km Helwin 1 (Transpower offshore, 2014, +/- 250 kV, 576 MW,85+45.5 km) for Nordsee Ost – 2x4.2 km, Meerwind phase 1 – 2x7.6 km and 2 – 2x 20 km Sylwin 1 (TenneT, 2014, +/- 320 kV, 864 MW, 159 + 45.5 km) for Dan Tysk– 2x9.7 km, Butendiek – 2x40 km and Sandbank 24 – 2x35 km Helwin 2 (TennetT, 2015, +/- 320 kV, 690 MW,85+45.5 km) for Amrumbank – 3x8 km, Hochsee Testfeld Helgoland – 2x4 km and Kaskasi – 2x3.5 km DolWin 3 (TenneT, 2017, +/- 320 kV, 900 MW, 84.5+76.5 km) for OWP Borkum Riffgrund West 1, OWP Borkum Riffgrund West 2 and OWP Borkum West 2
Operation of offshore wind power plants connected with HVDC, O.Gomis
• Context. Offshore wind power plants connected with VSC-HVDC.
• Functional requirements for offshore WPP connected with VSC-HVDC.
• Example of coordinated control for power reduction.
• Conclusions.
13 Operation of offshore wind power plants connected with HVDC, O.Gomis
WPP connected to VSC-HVDC Functional requirements
• Collect the wind power and inject it in the VSC-HVDC cable
• Provide support to the main AC grid • Provide support to the DC grid (if exists) • Ensure the proper offshore grid operation • Maintain stability in normal and fault conditions
14 Operation of offshore wind power plants connected with HVDC, O.Gomis
WPP connected to VSC-HVDC Functional requirements
Specific requirements: • Reactive power management. Offshore grid voltage control (HVDC rectifier + WTs) • Active power management • Offshore grid frequency control (VSC-HVDC rectifier) • Start/stop sequence • Fault ride-through capability • Main grid support:
– Voltage support – Frequency support may be required – Virtual (synthetic inertia) may be required – Power oscillation damping may be required
• Control coordination between WPP control and VSC-HVDC control • Operation under communication failure • Provide auxiliary power to the WPP when there is no available generation (no wind
or excessively high wind)
15 Operation of offshore wind power plants connected with HVDC, O.Gomis
Normal operation
16
Draft from Cigré B4-55 WG “HVDC connection of offshore WPP”
~=
Offshore Converter
OnshoreConverter
AC Grid Onshore
Converter Station
~=
Substation
Emergency
Power
Transformer Platform 1
P
P
P
P
P
P
P
P
P
P
P P
Operation of offshore wind power plants connected with HVDC, O.Gomis
Restricted operation
17
Draft from Cigré B4-55 WG “HVDC connection of offshore WPP”
Operation of offshore wind power plants connected with HVDC, O.Gomis
Main AC grid fault
18
Draft from Cigré B4-55 WG “HVDC connection of offshore WPP”
~=
Offshore Converter
OnshoreConverter AC Grid
Onshore
Converter Station
~=
Substation
Emergency
Power
Transformer Platform 1
P
P
P
P
P
P
P
P
P
P
P Fault
PHVDC chopper actuation
Operation of offshore wind power plants connected with HVDC, O.Gomis
WPP fault
19
Draft from Cigré B4-55 WG “HVDC connection of offshore WPP”
~=
Offshore Converter
OnshoreConverter
AC Grid Onshore
Converter Station
~=
Substation
Emergency
Power
Transformer Platform 1
P
P
P
P
P
P
P
P
P
Fault
P
P P
Operation of offshore wind power plants connected with HVDC, O.Gomis
Export cable fault
20
Draft from Cigré B4-55 WG “HVDC connection of offshore WPP”
~=
Offshore Converter
OnshoreConverter
AC Grid Onshore
Converter Station
~=
Substation
Emergency
Power
Transformer Platform 1
P
P P
Fault
Wind turbine power reduction
P
P
P
P
Operation of offshore wind power plants connected with HVDC, O.Gomis
Frequency response using WPP control
21
Draft from Cigré B4-55 WG “HVDC connection of offshore WPP”
~=
Offshore Converter
OnshoreConverter
AC Grid Onshore
Converter Station
~=
Substation
Emergency
Power
Transformer Platform 1
P
P
P
P
P
P
P
P
P
P
P P
Power reductionWPP CONTROL
GRIDOPERATOR
Onshore frequency /
WPP required active power
Operation of offshore wind power plants connected with HVDC, O.Gomis
Frequency response using VSC-HVDC converters
22
Draft from Cigré B4-55 WG “HVDC connection of offshore WPP”
~=
Offshore Converter
OnshoreConverter
AC Grid Onshore
Converter Station
~=
Substation
Emergency
Power
Transformer Platform 1P
P
P
P
P
P
P
P
P
P
P P
Frequency Change
Onshore frequency /
WPP required active power
Operation of offshore wind power plants connected with HVDC, O.Gomis
• Context. Offshore wind power plants connected with VSC-HVDC.
• Functional requirements for offshore WPP connected with VSC-HVDC.
• Example of coordinated control for power reduction.
• Conclusions.
23 Operation of offshore wind power plants connected with HVDC, O.Gomis
Operation of offshore wind power plants connected with HVDC, O.Gomis 24
Example coordination for power reduction
VSC-HVDC DBR Wind turbine DBR
Pitch angle
• How can we provide power reduction (without fast communication between offshore and onshore VSC-HVDC)?
– Onshore VSC-HVDC DBR, fast but available limited time. (not offshore ->footprint!) – Wind turbine DBR, fast but available limited time. – Pitch angle. Slow response but good for steady-state. – Fast wind turbine torque reduction with the power converter? Electrically possible, but
not allowed. (Turbine loads)
Example coordination for power reduction
25
PhD thesis, Agustí Egea (CITCEA-UPC)
WFC
E1
I1 GSC
E2
Cable 1
Inner loopilq*
Droop control
vlqd
E2*
ilqd
ilabc
vlabc vzabc
MPPT
Inner loop
iwtabc
T[θ]-1θg
θg
iwtabc
iwtqd
iwtqd
vwtabc
*
Inner loop
ipqd
vpqd
vpabc
*
ipabc
DC loop
Ewt
vpabc
vrabc
vrqd
Ewt*
ipqd
Ewt
T[γ]-1
vzabc
vlabc
vlqd vlabc
ilabc
E2
Inner loop
T[δ]-1
icqd*
Voltage loop
T[δ]
vcqd
icqd
vtabc
vtqdvcabc
icabc
icabcinabc
vcabc
inabc inqdvcqd*
vwtqd
vrabc
GSC chopper
E2
WTCWGC
∫
γ T[θ]-1
T[θ] δ δ
PLLϕ ϕ
T[ϕ]-1
T[ϕ
]
T[γ] vrqd
ipqd
γ
ONSHORE STATION
GSC CONTROL
Pitch controller
βpitch PwtPwt
*
WF power controller E1
E1min
Pw
t-ch
DETAILED WIND TURBINE
WINF FARM CONTROL
P2ch
PWFred
Power reduction
d/dt
.
PLL
GSC-DBRCONTROL
COMMUNICATION BUS
ωδ
OFFSHORE PLATFORM
Pwt
EDC
PDC
E2
E1
E1
E2
E2
max
min
max
min
nomE2
Example coordination for power reduction
26
PhD thesis, Agustí Egea (CITCEA-UPC)
Operation of offshore wind power plants connected with HVDC, O.Gomis
WFC
E1
I1 GSC
E2
Cable 1
Inner loopilq*
Droop control
vlqd
E2*
ilqd
ilabc
vlabc vzabc
MPPT
Inner loop
iwtabc
T[θ]-1θg
θg
iwtabc
iwtqd
iwtqd
vwtabc
*
Inner loop
ipqd
vpqd
vpabc
*
ipabc
DC loop
Ewt
vpabc
vrabc
vrqd
Ewt*
ipqd
Ewt
T[γ]-1
vzabc
vlabc
vlqd vlabc
ilabc
E2
Inner loop
T[δ]-1
icqd*
Voltage loop
T[δ]
vcqd
icqd
vtabc
vtqdvcabc
icabc
icabcinabc
vcabc
inabc inqdvcqd*
vwtqd
vrabc
GSC chopper
E2
WTCWGC
∫
γ T[θ]-1
T[θ] δ δ
PLLϕ ϕ
T[ϕ]-1
T[ϕ
]
T[γ] vrqd
ipqd
γ
ONSHORE STATION
GSC CONTROL
Pitch controller
βpitch PwtPwt
*
WF power controller E1
E1min
Pw
t-ch
DETAILED WIND TURBINE
WINF FARM CONTROL
P2ch
PWFred
Power reduction
d/dt
.
PLL
GSC-DBRCONTROL
COMMUNICATION BUS
ωδ
OFFSHORE PLATFORM
Pwt
• Context. Offshore wind power plants connected with VSC-HVDC.
• Functional requirements for offshore WPP connected with VSC-HVDC.
• Example of coordinated control for power reduction.
• Conclusions.
27 Operation of offshore wind power plants connected with HVDC, O.Gomis
Conclusions • Offshore wind power plants connected with VSC-HVDC have
special characteristics: – The VSC-HVDC converter needs to create an offshore grid where the
frequency can be freely chosen.
– As the offshore grid is an only “power electronics” grid, the protections need to be carefully designed. Standard approaches may not be useful.
– The interactions between wind turbines and VSC-HVDC converters need to be studied.
• Offshore wind power plants need to: – Collect the wind power and inject it in the HVDC cable
– Provide support to the main AC grid and DC grid.
– Maintain stability in normal and fault conditions
28 Operation of offshore wind power plants connected with HVDC, O.Gomis