Transcript Technical Issues related to Grid Interconnection of Wind

Grid Interconnection of
Wind Turbines
Presentation to GERC
Ahmedabad
07.02.09
M.P.RAMESH, former Executive Director
Centre for Wind Energy Technology
GERC posers
• GERC has put up the following questions:
– Intra-state grids
– Interstate regional grid
– Bulk quantity of wind/solar inputs in ‘low load
areas’ impact assessment
– Increasing wind/solar inputs - need for backing
down ?
– Limits?
GERC Posers
• What are problems associated with wind
power & commercial implications?
• Technologies for scheduling/dispatch
• On-line monitoring
• Solar power generation
• Relevance of intra-state grid connectivity for
major wind & solar energy inputs
• Some insight into the wind potential in GUJRAT
Some history
• Gujarat is THE FIRST STATE which experimented
with grid connected wind turbines.
• The state also was the first state to have
‘commercial wind farm’ at Mandvi.
• The state’s wind map shows second highest
potential nearly everywhere adding up to 10645
MW (installed) based on certain assumptions.
• CWET/MNRE would be getting the atlas prepared
for India shortly. We would then have a more
comprehensive idea about the possibilities.
Installable Wind Power potential in India (2006 estimate)
S.Nosta
llable
1
STATE
200-250
250-300
WPD RANGE (W/Sq.m)
300-400
400-500
500-600
COLOUR CODE
RED
VIOLET
GREEN
ORANGE
CYAN
600-800
800-2000
PINK
BLUE
STATEWISE
TOTAL
MW
2
ANDRAPRADE
SH
GUJARAT
3
KARNATAKA
4
KERALA
166
368
594
43
0
0
0
1,171
5
MADHYA
PRADESH
1014
5
0
0
0
0
0
1,019
6
MAHARASTRA
4339
245
0
0
0
0
0
4,584
7
ORISSA
250
5
0
0
0
0
0
255
8
RAJASTAN
4154
704
0
0
0
0
0
4,858
9
TAMILNADU
1253
1720
2381
162
14
0
0
5,530
10
WEST
BENGAL
32
0
0
0
0
0
0
32
32,679
10,819
4,683
395
17
0
0
48,593
WPDWISE TOTAL
7306
1489
173
0
0
0
0
8,968
7216
2842
587
0
0
0
0
10,654
6949
3441
948
190
3
0
0
11,531
WPD
range
Potential
(MW)
BASI
JASWANTHGAD
SAWA
200-250
(red)
7216
250-300
(violet)
2842
300-400
(green)
587
Total
10645
UNDARI
DHROBANA
TAGA
DAMOTAR
KHERWADA
SISODA
JAMANVADA
ADESAR
SIVALAKHA
MOTI SINDHOLI
VANDHYA
SURAJBARI
KUKMA
POLADIYA KERA
SINUGRA
BAYATH
BARI SADRI
SINAI
WARSHAMEDI
RATABHE
MUNDRA
GUJARAT
DEVGARH
NANDLI AHADA
MAMATKH
CHORAS
BODHINA
PADSOLI
KAWASA
DAHOD
OKHA
SUVARDA
HARIPAR
GALA
OKHAMADHI
KALYANPUR BHANDARIYA
NAVADRA
LAMBA
HARSHAD
BAMANBORE 1
JHABUA
MACHALIYA GHAT
LIMBARA
MESARIA
BAMANBORE 2
DHANDHALPUR
PAREWADA
MAHIDAD
K
SADODAR
BUTAVADAR
MOTA DADAWA
DHANK 2
DHANK 1
AMRAPAR (SETH)
GODLADHAR
ROJMAL
NANI KUNDAL
KAGAVAD
VALIYARPANI
SENDHVA
NAVI BANDER
SANODAR
KHAMBADA
JASAPAR
Wind farming
areas
KAMRAVAD
AMRAPAR (GIR)
CHAKLA
DUMDHA
VERAVAL
JAFRABAD
VELAN
BRAHMANVEL
TAKARMAULI
RAIPUR
DANDI
SAPUTARA
SAPTHASRINGIGAD
THOKALWADI
MALEGAON KARIYAT
THOKA
Gujarat wind Potential
• It is seen that a large part of
Gujarat has moderate wind
potential.
• But for a few pockets, the wind
turbines would have good steady
winds during monsoon months.
• A well defined May to August
SW high wind season & a
moderate NE wind season during
December-January.
• Year on year variations are well
with in reasonable limits
• Wind power quite evenly
distributed across the State.
Some time scales in grid management
• There are four levels in
grid management.
– Unit commitment – which works
on a scale of days
– Scheduling needed on a day
upon day basis
– Load following which has a time
scale of minutes to hours
– Regulation which happen over
seconds to minutes
• We need to understand that it
is a complex issue and needs
detailed analysis either to
accept or reject an idea.
Evacuation – The big picture –
Northern & Southern Grids
NR
NER
Freq - 1
ER
WR
- 5 Regional Networks in the Country
Freq - 2
SR
- Currently 4 Regional Networks merged
INDIA CURRENTLY OPERATING AT
“TWO” FREQUENCIES – NORTH & SOUTH
INTER-REGIONAL EXISTING CAPACITIES
INTER-REGIONAL PROPOSED CAPACITIES BY 2011-12
NORTHERN
REGION
4600 MW
13450 MW
NORTHEASTERN
REGION
ER
6450 MW
WESTERN
REGION
1300 MW
Weak link
SOUTHERN
REGION
EASTERN1000
REGION
MW
3700 MW
30,000 MW OF INTER-REGIONAL POWER BY
2011 -12
“NO Augmentation” proposed between
“Southern & Northern” Grids
SOURCE : CEA
Impact on grid and associated equipment
• As such, wind turbines and associated equipments are
designed to take care of each and every eventualities that the
installations would be subjected over their service life.
• Double redundant safety systems including electrical
equipments are a ‘type certification’ requirement.
• In India it is not possible to grid connect wind turbines which
do not have a valid type certificate.
• Therefore a wind farm would work much like a standard
power plant in all respects.
• The problems of first generation wind turbines have been
very largely addressed in the modern wind turbines.
• MODERN WIND TURBINES MEET THE MOST STRINGENT GRID
REQUIREMENTS FOR SAFE OPERATION.
Impact on grid and associated equipment
• After the area and capacity of a given wind
farm are decided, Wind farm design preceded
by detailed load flow analysis, impacts of
voltage & frequency excursions, harmonics,
seamless power factor controls and optimised.
• There are wind turbines which have facility to
provide leading pfs if required.
• Wind farm Substations are built to meet strict
standards laid down by the TRANSCos.
Backing down Thermal ?
• The question of backing down of thermal power stations due
to presence of large wind is open ended. It is a combination
of many factors.
• In a surplus power supply system there could be a need to
back-down some flexible generation facility (Hydro/gas based
system for example).
• In our context, when grid frequency is < 50 hz, there will be
some margins that takes care of the so-called infirm power.
• Therefore in all likely hood there may be no need to back
down thermal stations.
• If we integrate different regions effectively, flexibility would
improve so that resources could be utilized far more efficiently.
Is there any limit?
• In Denmark presently about 21 % of energy
consumed is supplied by wind turbines alone.
• Penetrations of wind power into local grids have at
times gone upto 60 % in good windy season.
• In Tamilnadu we have over 4000 MW against 12000
MW of the so called firm power. That is about 33%
on installed power basis. If we consider a 50% plf in
high wind season, we are looking at a penetration
level of18% on an average.
• As such there is no limit. It essentially depends on
resources and grid management strategies.
Infirm power?
• EB Comments from a state that has topped the Wind
Power deployment for decades has this to say:
“….. while occasionally the wind slows down in one
location leading to decreased output in a particular
location (also within the particular pass itself, the wind
mills are installed over a radius of 30 to 40 KM),
locations with high penetration of wind energy would
compensate for the same. As a result, it typically takes
much time or even hours for the total wind energy
output of a region to change significantly. This makes it
relatively easy for the utility system operators to
accommodate these changes without relying on the
reserves i.e. slowly taking the tag of ‘infirm power’
out of wind energy”.
Effect of aggregation
• Just to illustrate the observations of the EB
engineers some sample wind farms in
Karnataka were chosen.
• A total capacity of about 300 MW from three
areas within a radius of 50 km were
considered.
• Real time data from these wind farms have
been collected and the outputs summed up to
on a 24 hour basis during high wind month
and a moderate wind month.
0:00
0:30
1:00
1:30
2:00
2:30
3:00
3:30
4:00
4:30
5:00
5:30
6:00
6:30
7:00
7:30
8:00
8:30
9:00
9:30
10:00
10:30
11:00
11:30
12:00
12:30
13:00
13:30
14:00
14:30
15:00
15:30
16:00
16:30
17:00
17:30
18:00
18:30
19:00
19:30
20:00
20:30
21:00
21:30
22:00
22:30
23:00
23:30
Power (MW)
300
A Windy Day (July '08)
250
200
150
100
50
0
time of the day
20 MW
48 MW
74 MW
113 MW
44 MW
TOTAL
120
100
80
0:00
0:30
1:00
1:30
2:00
2:30
3:00
3:30
4:00
4:30
5:00
5:30
6:00
6:30
7:00
7:30
8:00
8:30
9:00
9:30
10:00
10:30
11:00
11:30
12:00
12:30
13:00
13:30
14:00
14:30
15:00
15:30
16:00
16:30
17:00
17:30
18:00
18:30
19:00
19:30
20:00
20:30
21:00
21:30
22:00
22:30
23:00
23:30
Power (MW)
140
A Moderate windy day (September)
Though there is much variation,
the ramp-up & ramp down
happens over several hours
60
40
20
0
Time of the day
20 MW
48 MW
74 MW
113 MW
44 MW
TOTAL
Some observations
• With more and more wind farms coming on
stream from different geographical locations,
the averaging effect will be even more
pronounced.
• The changes in delivered power are not drastic
and sudden.
• It provides time to the system manager to take
corrective measures
Technologies available for scheduling/dispatching
• A system manager has to continuously monitor both the
supplies and loads.
• While supplies could be controlled to some extent, loads can
only be anticipated and corrective measures taken.
• In this dynamic situation it is important to note that it is a
balancing act with or without wind/solar power on the grid.
• With wind having its variability, the management would have
to be only slightly more innovative.
• There are emerging technologies to forecast in short term
(horizon of 60 hours).
• Validation and implementation is some distance away.
Some
forecast
results
It may be seen that the general trends are
predicted with some degree of uncertainty.
There are issues of input data for such exercises
such as outputs of Global Circulation Models.
Accuracies of input data for GCMs etc. are again
sources of errors.
It is a well known fact that the model outputs will
come with uncertainties and validation takes some
time, funds and effort.
On-line monitoring
• Online monitoring of wind turbines is a reality
of the day. It is not uncommon in new wind
farms. They are specifically designed SCADA
systems used to centrally monitor and control
wind farms in a given area.
• It is possible to obtain near – online info from
wind farms in a limited way.
• Though theoretically it is possible to have
GSM connectivity, V-SAT terminals etc..,
bandwidth related issues still exist.
Intra-grid
• Studies have shown that it is most desirable to have
these connectivity's in place.
• In the context of RE technologies, it would add some
more flexibility to the local grid management to have
conduits to bigger networks.
• Inter-regional exchange of power has larger and
generally positive ramifications.
• It is much like the ‘golden quadrilateral’ which has
virtually revolutionized connectivity to rural India.
• Thank You for your attention.