IEEE Tutorial on Wind Generation Modeling and Controls
Presented by: Dynamic Performance of Wind Power Generation Working Group
Sponsored by: Power System Dynamic Performance Committee and
Wind Power Coordinating Committee
IEEE PES PSCE Meeting, Seattle, WA, USA – March, 2009
Section 6c
Planning and Operations Impacts and
Standards
Kj til Uhlen
Kjetil
Uhl
Abraham
Ab h
Ellis
Elli
SINTEF
Sandia National Laboratories
Outline
• Planning and Operations Challenges
– Transmission
a s ss o Sys
System
e Impacts
pac s
• Grid Codes and Harmonization
• Examples on Wind Integration Studies and
Transmission System Impacts
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
2
Outline
• Planning and Operations Challenges
– Transmission
a s ss o Sys
System
e Impacts
pac s
• Grid Codes and Harmonization
• Examples on Wind Integration Studies and
Transmission System Impacts
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
3
What are the main challenges?
Economy and Security:
• Power system security
– Frequency Control and Regulation
– Voltage Control and Regulation
– Risk of blackouts and loss of load (reliability, voltage quality)
• Operational
O
ti
l monitoring
it i and
d control
t l
• Technical and functional requirements for grid connection
• Power balance
– Risk of capacity shortage (Rationing
(Rationing, loss of load / rolling blackouts)
• Operation planning
• Balance management
• Energy planning
– Risk of energy shortage (high prices)
• Long-term planning
• Investments in transmission and generation
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
4
What is special about wind power?
Active power
Frequency
Voltage
Reactive power
Energy input:
-Fuel
-Reservoir
Reservoir
G
Grid
Active power
Frequency
Voltage
Reactive power
Energy input:
-Wind
Wind
•
•
vw
G
Grid
The wind p
power p
plant lacks a controllable “energy
gy storage”
g on the input
p
Generation planning becomes more challenging
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
5
Power System Security
• Challenges in operation:
– Voltage and Frequency Control and Regulation
– Monitoring and control (transfer limits)
– Control Center tools (from steady state analysis Æ more
dynamic information)
• Challenges,
Challenges preventive:
– Technical and functional requirements for installations
and plants connected to the grid
– Security standards (from pure N-1 Æ risk based criteria)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
6
Power Balance
• Risk of capacity shortage (Rationing, loss of load / rolling
blackouts)
– Operation planning
– Balance management
• Challenges:
–
–
–
–
–
–
Frequency control
Frequency response (primary reserves)
Balancing services (how to operate the system?)
Reserves (how to allocate reserves?)
Congestion management (good market solutions?)
Need for better forecasting tools
¾ Possibilities:
– Demand side participation more important
– Increased value of hydropower !
– Wind Power Management
g
((e.g.,
g limit ramp
p rates, output
p level))
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
7
Energy Planning
• Risk of energy shortage (high prices)
– Long-term planning and Investments in transmission and generation:
– More difficult due to high variations in energy supply
• Well known problem for hydro-dominated systems
• A new challenge for systems dominated by thermal generation.
• Challenges:
– New requirements and demand for planning tools:
• Need for higher time resolution
• Need for tighter integration of market models and network analysis tools
tools.
– Increasing need for dynamic studies (voltage stability, transient
y, etc.))
stability,
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
8
Available energy from wind and hydro power
(example of annual variations)
Normalised annual production (%)
140
120
100
80
60
Wi d
Wind
Hydro
40
20
0
1960
1965
1970
1975
Year
1980
1985
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
1990
9
Analyzing grid capacity
35
250
Wind
farm
Hydro inflow (MWh)
200
Win
nd speed (m/s)
30
150
25
20
15
10
5
100
0
Hydro
plant
p
50
Distribution grid
1000 2000 3000 4000 5000 6000 7000 8000
Time (hour)
P
40
35
Consumers loa
ad (MW)
0
1000 2000 3000 4000 5000 6000 7000 8000
Time (hour)
Bottleneck !
30
25
20
15
Plim
P(t) ?
P(t)=?
10
1000 2000 3000 4000 5000 6000 7000 8000
Time (hour)
Regional
transmission grid
Ti
Time
/ Duration
D ti
Main transmission grid
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
10
Summing up..
•
Wind energy changes the power system:
– Variable generation at new locations
– Higher demand for power transmission
– Larger variations and more frequent changes in power flows
•
Energy planning:
– Wind energy
gy makes a p
positive contribution
– Main challenge to develop good planning tools
•
Power system security:
– No big difference between wind and other conventional generation
– Grid connection requirements (grid codes)
– Focus on monitoring and control, competence and tools
•
Power balance:
– A main challenge for large scale integration of wind power
– Balance management, reserves, wind forecasting tools,..
– Market solutions
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
11
Outline
• Planning and Operations Challenges
– Transmission
a s ss o Sys
System
e Impacts
pac s
• Grid Codes and Harmonization
• Examples on Wind Integration Studies and
Transmission System Impacts
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
12
System requirements - Motivation
• That wind power plants will (and should) face similar
requirements as conventional power plants regarding
controllability and ability to provide relevant system
services, contributing to :
– Maximizing power transfer capacity
– power balance and reserves (capacity credit this is jurisdiction and
not global)
• Control requirements:
– Power Management and Frequency Regulation
– Voltage control, and reactive power compensation)
– Both on primary and secondary control level
• Key questions:
– What are the system performance requirements? (technical issue)
– Which system services should be provided by wind farms?
(economic issue to wind operator or to system operator)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
13
“Grid Codes”
• The aim is to ensure system control properties
th t are essential
that
ti l ffor the
th reliability
li bilit off supply,
l
security in operation and power quality in the
short end long term
term.
– General laws, regulations and agreements apply
• Specific grid codes for large scale wind power are
being established in most countries with
significant wind power developments
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
14
Grid codes for wind power
•
Power control
–
–
–
•
Frequency and voltage deviations
–
•
Responsibility
p
y
Tolerance.
Communication (between wind farm and grid operator, ..)
–
•
Stability requirements (transient) (Various types of faults)
Protection of the wind farm against grid faults
–
–
•
Reactive compensation
Control Requirements (Mvar control, power factor control, Voltage control, etc.)
Voltage quality (Voltage variations, dips, flicker, harmonics, etc.)
Response to grid faults
–
•
Frequency and voltage limits where wind farms shall operate and when they shall stop
Reactive power and Voltage control
–
–
–
•
Ability to control power output via power limiting and/or ramp rate limiting
Frequency control (primary reserves)
Start and stop
stop, limits on po
power
er gradients
gradients,..
Responsibility for providing information, operational data, etc.
R
Requirements
i
t regarding
di d
documentation,
t ti
analysis,
l i ttesting,
ti
etc.
t
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
15
Different Requirements for Different
Countries
• Germany
– Part of a strong interconnected system (UCTE)
– Thermal dominated system
• Denmark
– WTs spread at distribution level
– Portfolio still dominated by wind turbines with induction machines
with limited controllability
• England & Wales and Scotland
– Large isolated system
• Ireland
– Small isolated system
– Big potential for wind power
• Norway
– Part of a larger interconnected system (Nordel)
– Highly
g yd
distributed
st buted and
a d less
ess interconnected
te co ected system
syste
– Hydro power dominated system
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
16
Different Requirements for Different
Countries
• United States
– Large, transmission-connected wind power plants
– Big potential for wind power in some regions
– Transmission capacity constraints to major wind
resource areas
– Standards still evolving
• Some jurisdiction issues (FERC, NERC)
• Canada
– Some regions hydro-dominated, some not
– Alberta example
• Thermal power dominated system
• Low interconnection capability to the Western US systems
• Big potential for wind power
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
17
Comparison of the Different Country
Requirements
General Considerations:
• Deal with
ith same topics
topics, b
butt with
ith different
descriptions
• Lack of harmonization on wind facility
requirements
• Difficult to make comparisons
• Example:
– Reactive Contribution
– Fault Ride Through (FRT)
– Frequency
q
y Regulation
g
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
18
Reactive Contribution
• To maintain voltage within specific limits
• Reactive power generated locally where it is
needed
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
19
Reactive Contribution: Germany < 100 MW
100
90
80
Ac
ctive Power (% P
Pn)
70
60
50
40
30
20
10
Capacitive
Inductive
0
-50
-40
-30
-20
-10
0
10
20
30
40
50
Reactive Power (% Pn)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
20
Reactive Contribution: Germany >100 MW
100
90
80
Activ
ve Power (% Pn))
70
V i t2
Variant
Variant 1
60
50
40
30
20
10
Inductive
Capacitive
0
-50
-40
-30
-20
-10
0
10
20
30
40
50
Reactive Power (% Pn)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
21
Reactive Contribution: Denmark
100
90
80
Acttive Power (% Pn
n)
70
60
50
40
30
20
10
Inductive
Capacitive
0
-50
-40
-30
-20
-10
0
10
20
30
40
50
Reactive Power (% Pn)
Reactive Power Mean Value over 10
sec is kept within the control band
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
22
Reactive Contribution: Ireland
100
90
80
Activ
ve Power (% Pn)
70
60
50
40
30
20
10
Inductive
Capacitive
0
-50
-40
-30
-20
-10
0
10
20
30
40
50
Reactive Power (% Pn)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
23
Reactive Contribution: England, Wales and
Scotland
100
90
80
Ac
ctive Power (% P
Pn)
70
60
50
40
30
20
10
Inductive
Capacitive
0
-50
-40
-30
-20
-10
0
10
20
30
40
50
Reactive Power (% Pn)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
24
Reactive Contribution: Norway
100
90
80
Ac
ctive Power (% P
Pn)
70
60
50
40
30
20
10
Capacitive
Inductive
0
-50
-40
-30
-20
-10
0
10
20
30
40
50
Reactive Power (% Pn)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
25
Reactive Contribution: Comments
• Germany (<100 MW), England, Norway
and
d Ireland
I l d (relaxation
( l
ti att 50 %P) h
have th
the
g2
same requirements 0.95 (ind./cap.)
• Germany (>100 MW) most strict in over
excitation ((0.90)) less in under excitation
(0.975).
• Denmark has the most relaxed
requirements
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
26
Slide 26
g2
not big deal since with only 20 % active power output all the WTs would be connected and hence the total reactive power capability
would remain intact.
giuseppd, 3/27/2006
Reactive Power/Voltage Control in the US
• Existing NERC voltage control standards are for
synchronous generators, not wind
• FERC 661-A Power Factor Design Criterion for
Wind
– Somewhat vague; transmission provider’s
provider s
interpretation vary
– Reactive support at partial output not defined
– Dynamic vs Static support not well defined
• Canada jurisdictions have their own standard.
– Alb
Alberta requires
i
0
0.9
9 PF over excitation
i i and
d0
0.95
9 PF
under excitation at the low voltage side of the facility
step up transformers
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
27
US FERC Reactive Support Standard
• FERC Power Factor Design Criteria:
– Maintain a power PF within a range of +/- 0.95
0 95 at the POI…
POI if the
System Impact Study demonstrates that such requirement is
needed for safety or reliability
– Provide dynamic voltage support
support… if the System Impact Study
demonstrates that this is required for safety or reliability
– SVC or STATCOM can be used to meet standard
• Possible
P
ibl iinterpretations
t
t ti
off th
the FERC rule
l
– Always require +/-0.95 pf range at the POI; prescribe what portion
must be dynamic (e.g., 50%)
– Case-by-case basis
• There is no consistent, widely-applied approach to “demonstrate”
need.
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
28
Reactive Support Standards in Canada
•
Manitoba-Hydro
Two examples
•
AESO
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
29
Fault Ride Through (FRT)
Wind Turbine should stay connected during a
y
to avoid large
g and sudden
fault in the system
losses of generations which could lead to
g up
p in black outs.
cascade events ending
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
30
FRT: Germany
Low short circuit current
dP/dt>20% Pn/sec
dP/dt>5% Pn/sec
High short circuit current
Extra high (220 kV) and high voltage (60 to 110 kV)
Rate of raise of active power: 20% of rated power pr second (i.e. within 5 sec )
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
31
FRT: Denmark (Turbine Simulation Test)
0.25
10000
•Three-phase on random line or transformer with permanent
disconnection without any attempt of re-closing (FCT 0.10 seconds).
•Two phase fault on random line with unsuccessful re
re-closing
closing (FCT will
be typically 0.1 seconds, the period of deionization 0.3 seconds and the
FCT at the unsuccessful re-closing 0.1-0.5 seconds).
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
32
FRT: Ireland
Within 1 sec of the voltage recovery, WF shall provide
90% of its available active power.
During the voltage dip active power in proportion
to the retained voltage and maximize the reactive
Current.
625
10000
High voltage systems (60 to 110 kV)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
33
FRT: England, Wales and Scotland
1200
2500
10000
Requirements for super grids: 275 kV and 400 kV
Rate of rise for Active power: immediate power recovery for faults up to 140 ms;
In proportion to the retained voltage for faults greater than 140 ms
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
34
FRT: Norway
< 200 kV
> 200kV
10000
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
35
FRT: Comments
• Voltage dip: most strict in England (NB applies at
highest voltage levels 275 kV, 400kV) and
Germany (low short circuit current)
• Duration of the voltage dip: 625ms in Ireland and
Germany
• Rate of rise of electrical power:
– England: immediate (<140
(
ms),
) in proportion to the
retained voltage (>140 ms)
– Ireland: in proportion to the retained voltage
– Germany: 5 sec or 20 sec (UCTE 550GW)
– Norwayy up/down
p
regulation
g
10-100 % P within 1 min
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
36
Low Voltage Ride
Ride--Through (LVRT) Standards
in North America
• Standards that apply
– WECC LVRT standard (applies to all generators in the Western
I t
Interconnection).
ti ) Adopted
Ad t d in
i 2005
– FERC Order 661-A (applies to wind generators only) Based largely on the
2005 WECC standard
– FERC LVRT standard also applies in the Western US
US, so there are
some conflicts. WECC trying to harmonize, conform
– NERC does not have a North-America-wide LVRT standard. They
are working on itit.
– Some utilities have their own variation (e.g., PNM)
• Jurisdictions in Canada ((Provinces)) have their own LVRT
standards
• Standard still evolving. Need to harmonize.
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
37
FERC (US(US-wide) LVRT Standard
• Applies to wind generators only
• Standard
– Tolerate 3-ph faults cleared in normal time, and singleline-to-ground faults with delayed clearing, unless
• Wind generator is radially connected to the fault
– Maximum clearing time not to exceed 9 cycles
– Voltage
V lt
d
during
i ffault
lt can b
be 0 att hi
high
h side
id off station
t ti
transformer
• During
g transition p
period ((through
g Dec. 2007),
) exception
p
g
granted
if voltage dipped 0.15 pu
– Existing generators are exempt unless the generators
are replaced
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
38
WECC (Western Reliability Entity) LVRT
Standard
• Applies to all generators 10 MVA or above
• Standard
– Tolerate 3-ph faults cleared in normal time, and singleline-to-ground faults with delayed clearing, unless
•
•
•
•
Voltage at high side of station transformer dips below 0.15 pu
Fault is internal to the power plant (e.g., collector system)
Generator is radially
y connected to the fault
Tripping is intentional as part of a special protection scheme
– After fault, don’t trip if recovery is acceptable for a load
(e g 20% voltage dip for 40 cycles)
(e.g.,
– Existing generators are exempt until replaced
• Some changes being considered to harmonize
with FERC (e.g., zero voltage ride-through)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
39
LVRT and Fault Location
POI or
connection
to the grid
Collector System
Station
Interconnection
Transmission Line
Individual WTGs
Feeders and Laterals (overhead
and/or underground)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
LVRT standard
applies
LVRT standard
Does not apply
40
LVRT Standards In Canada
Two examples
AESO LVRT Standard
Manitoba Hydro LVRT standard
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
41
Frequency Regulation
• Due to unbalance between load and
g
generation
• All generator plants shall be able to operate
within a certain frequency range above and
below 50/60 Hz
• Regulation performance and frequency
deviations
• Requirements
R
i
t ffor frequency
f
control
t l
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
42
Frequency Regulation: Germany
120
Additionall R
Additi
Requirements:
i
t
deviating power Output
according to the control
condition (primary control if
applicable)
pp
)
Active Power [%]
100
80
60
Basic Requirement
40
20
0
47
47,5
48
48,5
49
49,5
50
50,5
51
51,5
52
52,5
53
Fr [Hz]
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
43
Frequency Regulation: Denmark
120
Active Power [%]]
A
100
Only down
regulation
without
reduced
production
80
60
Set point
value at
downward
regulation
40
20
0
47
47,5
48
48,5
49
49,5
50
50,5
51
51,5
52
52,5
53
Fr [Hz]
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
44
Frequency Regulation: Ireland
120
Acttive Power [%]
100
80
49.8-50.2 Hz
60
40
Reduced Active power in the
normal range, allowing for an
i
increase
iin active
ti output
t t if th
the
frequency falls.
20
0
47
47,5
48
48,5
49
Each WF has two power-frequency
power frequency control curves.
curves
The setting points will vary for each WF and shall
be set by the TSO
49,5
50
50,5
51
51,5
52
52,5
53
Fr [[Hz]]
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
45
Frequency Regulation: England, Wales and
Scotland
120
100
Active Power [%]
A
95%
80
60
40
DC Converter
Stations
20
0
47
47,5
48
48,5
49
49,5
50
50,5
51
51,5
52
52,5
53
Fr [Hz]
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
46
Frequency Regulation: Norway
Normal Operation
49.5-50.5 Hz
120
Activ
ve Power [%]
100
Frequency
q
y regulation
g
with regulation reserve
80
Reduced Power
Output
Continuously
60
Without Power
Reductions for
at least 30 min
40
Reduced Power Output
At least
l
t 20 sec
20
0
47
47,5
48
48,5
49
49,5
50
50,5
51
51,5
52
52,5
53
Fr [Hz]
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
47
Frequency Regulation: Comments
• Germany, Norway and England require the
same capability of delivering full power in the
range 49,5 - 50,5 Hz.
• England and Norway have more strict
requirements below 49.5 Hz (95% P) than
G
Germany
(80%)
• Capability requirement for operating WF at
reduced power in Ireland, Norway and Denmark
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
48
Summing Up
•
Little harmonization:
– Different network conditions lead to different requirements
•
Denmark: First g
grid code with rather relaxed requirements
q
– WFs are spread out in the distribution network. Has not observed
severe system problems due to disconnection of WFs
– Portfolio is still dominated by wind turbines with induction machines
•
G
Germany
and
d England:
E l d F
Focus on FRT
– Risk of disconnection and cascading outages were the main drivers for
the development of the grid code
•
Ireland: More focus on frequency control
– Power/frequency control is important in a small isolated system
•
Norway: focus on reactive power requirements
– Reactive power is important being generated locally and not transmitted
over long distances
•
US: Focus is still on developing appropriate standards
– Existing standards lead to different interpretations
– NERC beginning to take lead role
•
Canada: Approach similar to Europe
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
49
Outline
• Planning and Operations Challenges
– Transmission
a s ss o Sys
System
e Impacts
pac s
• Grid Codes and Harmonization
• Examples on Wind Integration Studies and
Transmission System Impacts
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
50
Examples
illustrating relevant problems related to system
requirements (grid codes):
1) Example to illustrate the need for (and the meaning of)
”fault
fault ride through capability
capability”.
2) Example to show the need for voltage control and reactive
compensation
ti capability
bilit
3) Example to illustrate problems related to congestion
management and balancing control (frequency control)
q
y response
p
4)) Power control and frequency
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
51
1. Transient stabilitet
(Fault rideride-through capability)
10000
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
52
Test System and Parameters
SVC 130 MVA
C
Compensation
i
110 km
Grid
22/0.69kV
BUS7
~
BUS8
Load
P 600 MW
Q 100 MVA
25 km
BUS1
22/132 kV
BUS3
~
BUS5
BUS6
Compensation
22/0.69kV
Cap. bank
20 MVA
BUS2
Wind Turbines
2 X 100 MVA
22/132 kV
BUS4
~
Synch. Gen.
200 MVA
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
53
Dynamic Analysis: Transient Stability (1)
Fault and tripping of a transmission line
3 Phase Fault cleared in 0.150 s
Compensation
Grid
~
Voltage at different terminals
1.2
~
SVC Reactive Power
Voltage BUS6
Voltage BUS3
Voltage BUS1
Compensation
p
1.1
1
140
0.9
Voltag
ge[p.u]
SVC Reactive Power[MV
Var]
120
100
80
0.8
07
0.7
~
0.6
0.5
60
0.4
40
03
0.3
20
0
0.2
0
2
4
6
8
10
time[sec]
0
2
4
6
time[sec]
8
10
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
54
Dynamic Analysis: Transient Stability (2)
Fault ride through with SVC rated 150 MVA
3 Phase Fault cleared in 0.150 s
Compensation
Grid
~
1.2
~
1.1
220
1
200
0.9
Voltag
ge [p.u.]
Reactiva Power [MV
Var]
180
160
140
0.8
0.7
0.6
120
~
0.5
100
80
0.4
60
03
0.3
40
0.2
0
20
Compensation
p
0
2
4
6
8
10
BUS6
BUS3
BUS1
2
4
6
8
10
Time [s]
Time []p.u.
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
55
Modelling and simulations
Traditional vs. nonnon-traditional modelling
CIMTR3
Tturb
Pmech
AG
“Traditional” modelling of
wind farm; fixed
mechanical power as
input to the generator
model
CIMTR3
ACTIV
ωt
Dynamic
wind
turbine
model
Pmech
AG
Modelling of the wind farm with
a dynamical wind turbine
model with fixed mechanical
torque as input to the turbine
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
56
Traditional vs. nonnon-traditional modelling
Voltage response after a temporary three-phase short-circuit at first PCC
1.1
1
1
0.9
Voltage bus 70441 [ pu]
Voltage bus 71352 [p
pu]
Fixed torque input
0.8
Fixed torque
q input
p
With dynamic WT-model
0.7
0.6
0.5
0.4
0.3
With dynamic WT-model
0.8
0.6
0.4
0.2
0.2
0.1
0
4
5
6
7
Time [s]
8
9
Voltage at local bus (0.69 kV) at
the wind farm
10
4
5
6
7
Time [s]
8
9
10
Voltage at first point of common
connection (PCC, 132 kV)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
57
Traditional vs. nonnon-traditional modelling
Effect of shaft stiffness on the response
characteristics
1.2
Fixed torque
(K = ∞)
1.1
Voltage bus 7
71352 [pu]
1
0.9
0.8
K = 2.0
Base case, K = 0.61
0.7
K = 0.41
0.6
Increasing stiffness
0.5
0.4
0.3
0.2
4
5
6
7
Time [s]
8
9
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
10
58
Fault and line outage (Effect of power level)
Induction generator
type of wind farm
with external
compensation
(STATCOM 75 M
Mvar))
Variable speed
Wind farm with
DFIGs (internal
compensation)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
59
2. Voltage control and reactive power
compensation
•
•
•
The possibilities depend on system configuration (generator
g
)
solution and network integration)
Previously, not all wind farms have had the possibility to supply
reactive power.
The system requirements will obviously influence the choice of
technology in the future.
Example:
• Relevant for larger wind farms in Norway (50 – 100 MW)
– Realistic network model for (windy) sites in Mid-Norway
– Regional 66 kV grid (long distances to main transmission grid)
•
Choice of technical solution is the main factor determining the
maximum size of the wind farm.
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
60
The importance of reactive compensation
P
V
0.02 + j0.13
Q
S p en n in gV[p[p.u.]
.u .]
Voltage,
V=1.0
0.06+ j0.37
0.04 + j0.25
11.18
18
1.12
V(P)ved
at Q
Q ==-0.35P
-0.35P
V(P)
“Induction generator”
"Asynkrongenerator"
1.06
1
V(P) at Q = 0
0.0
0
V(P)
ved Qfactor
= 0.0
“Power
"Mvar-regulering"
control”
0.94
0.88
0.82
V(P)ved
at Q
Q == 0.2P
V(P)
0.2P
“Voltage
Voltage control
control”
"Akti kompensering"
"Aktiv
k
i "
(spenningsregulering)
0.76
0.7
0
20
40
60
80
100
Akti power,
effekt
ff kt [MW]
Active
A tiAktiv
P [MW]
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
61
3. Example related to congestion management and
balancing control in Nordel (frequency control)
•
•
•
•
Frequency
q
y control reserves
Congestion management
Balancing services
R
Reserves
• Illustrating Nordic collaboration and sharing of reserves
across synchronous interconnections (UCTEÅÆNordel)
• E
Example
l iis ffrom 8
8. JJanuary 2005
– nearly 2000 MW wind power disconnected due to
severe storm in Southern Scandinavia
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
62
Western Denmark (Energinet.dk)
MW
GWh
Central power plants
3,516
16,161
Decentralised CHP units
1,567
6,839
Decentralised wind turbines
2,374
4,363
Offshore wind farm Horns Rev A
160
Consumption
21,043
Maximum load
3,780
Minimum load
1,246
Capacity export to UCTE
1,200
Capacity import from UCTE
800
Capacity export to Nordel
1,560
Capacity import from Nordel
1,610
Key counts of the power system of Western Denmark for the year 2003
(Source: Energinet.dk)
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
63
Elspot areas and transmission capacities
NO2
NO1
1000 MW
FI
SE
950 MW
DK1
DK2
1200 MW
800 MW
To Germany
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
64
Real life case – balance management
•
•
At 8 January 2005 a strong storm crossed
over Denmark
The wind farms of western Denmark at first
produced close to rated power, but then
started to cut out due to the excessive wind
speed (+ 25 m/s) – the wind production were
reduced from about 2200 MW to 200 MW in
a matter of 10 hours
Data for DK1, west Denmark 2003
+/-1000 MW
670/630 MW
SE
MW
Central power plants
3,516
Decentralised CHP units
1,567
ece t a sed wind
d tu
turbines
b es
Decentralised
2,374
,3
Offshore wind farm Horns Rev A
NO1
DK1
DK2
160
Maximum load
3,780
Mi i
Minimum
l d
load
1 246
1,246
Germany
800/1200 MW
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
65
8 January 2005
2500
2250
2000
M
MWh/h
1750
1500
1250
1000
750
500
250
0
-250
-500
-750
Exchange DK1 -> NO1
Balancing power (NO1)
Windpower DK1
-1000
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Hour
Source: NORDPOOL
The case demonstrates that the existing marked based mechanisms can
handle large variations in (wind) generation and demand
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
66
Balance management and balance settlements
• NORDEL has a common real-time balancing
market
k t
– Regulating power market (RK)
– Generators and large consumers can participate
• Settlement of deviations from plans:
– General principle: Deviations are paid/charged
according
g to the regulating
g
gp
power p
price ((RK p
price))
– Stronger incentive to follow plans with the future “twoprice” settlement (ELSPOT or RK-price)
– Nordic
N di h
harmonisation
i ti
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
67
Settlements of deviations from plans
One--price (presently in Norway)
One
Generator
Surplus p_Spot
Gain
p_RK
p_RK
p_Spot
Loss
Pplan Pa
Pplan Pa
Deficit
p_RK
p_Spot
SYSTEM
Surplus
p_Spot
Loss
Pa Pplan
Gain
p_RK
Deficit
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
Pa
Pplan
68
Settlements of deviations from plans
Two-price (Future in Nordel)
Generator
Surplus p_Spot
No gain
p_RK
p_RK
p_Spot
Loss
Pplan Pa
Pplan Pa
Deficit
p_RK
p_Spot
SYSTEM
Surplus
p_Spot
Loss
Pa Pplan
No gain
p_RK
Deficit
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
Pa
Pplan
69
4. Power control and frequency response
• Power control
– Wind farm control
– Ability to operate at reduced power output
– Relevant as a system control / system protection
functionality
• Automatic frequency
q
y control
– Frequency response relevant in certain conditions
• At very large scale wind integration
• Grid areas exposed to risk of islanding operation
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
70
Power control
Wind Farm Controller
Pkan
Pkan
Pbør
Pbør
Absolute power limit
Delta power limit
Pkan
Pkan
Pbør
Power gradient limit
Pbør
Block regulation
Source: Energinet.dk
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
71
Available power
Power
P
Power
P
Primary reserves (Frequency response)
d
droop
Set-point power
Available power
Reserve power
Frequency
Reactiive power
Power
Time
Time
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
droop
Voltage
72
Power/frequency control
Frequency response
HZ
R = 2Pn/δ
R = 100 MW/Hz
δ =6%
Pn = 300 MW
50.0
49.9
49.5
FR
10 MW
DR
min 15 MW
MW
Pa
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
Pn
73
Power/frequency control
Frequency response
Windfarms contribution to primary control
Grid frequency
50
Reference case
Variable speed
p
wind
Wind P
Power Output[p.u.]
Frrequency[Hz]
49.8
•Low wind
•Variable
speed
d
49.6
49.4
0.66
0.64
Transient contribution
0.62
0.6
0.58
49.2
0
W indfarm-1
W indfarm-2
W indfarm-3
0.68
50
100
150
time[sec]
Grid frequency
200
20
40
60
80
100
time[sec]
Windfarms contribution to primary control
Reference case
Fixed speed wind
49.8
Frequency
y[Hz]
•High wind
•Fixed
speed
49.6
49.4
Wind Power Ou
utput[p.u.]
50
1.03
1.02
1.01
1
49 2
49.2
0
50
100
time[sec]
150
200
Windfarm-1
Windfarm-2
Windfarm-3
1.04
0.99
Transient
and steady state
contribution
20
Dynamic Performance of Wind Power Generation Working Group – IEEE PES PSCE – Seattle, WA
40
60
time[sec]
80
100
74