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Indian Power System likely impacts and preparedness - A report
SOLAR ECLIPSE st21 June 2020
Power System Operation Corporation Ltd.Power System Operation Corporation Ltd.(A Government of India Enterprise)(A Government of India Enterprise)
Power System Operation Corporation Ltd.(A Government of India Enterprise)
May 2020May 2020May 2020
SOLAR ECLIPSE st
21 June 2020
Power System Operation Corporation Ltd.(A Government of India Enterprise)
Indian Power System likely impacts and preparedness - A report
May 2020
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 1 of 99
Table of Contents Executive Summary ................................................................................................................................ 6
7.1 Northern Region ........................................................................................................................ 43
7.2 Western Region ......................................................................................................................... 49
7.3 Southern Region ........................................................................................................................ 54
Chapter - 8 : Utility scale solar power plant controller ............................................................ 61
Chapter - 9 : Summary and Recommendations ........................................................................... 63
Annexure- I .............................................................................................................................................. 67
Annexure- II ............................................................................................................................................. 71
Annexure- III ........................................................................................................................................... 72
Annexure- IV ............................................................................................................................................ 81
Annexure- V ............................................................................................................................................. 83
Annexure- VI ............................................................................................................................................ 84
Annexure- VII .......................................................................................................................................... 85
Annexure- VIII ......................................................................................................................................... 88
Annexure- IX ............................................................................................................................................ 90
Annexure- X ............................................................................................................................................. 94
Annexure- XI ............................................................................................................................................ 97
Table 21: Tamil Nadu hydro generating stations ........................................................................................ 60
Table 22: Northern and Western Region ISGS generating plants (Gas and Hydro) ................................. 64
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 5 of 99
List of Acronyms
ATC: Available Transfer Capability
CEA: Central Electricity Authority
FGMO: Free Governor Mode Operation
IST: Indian Standard Time (UTC+05:30Hrs)
ISTS: Inter State Transmission System
ISGS: Inter State Generating Station
IEGC: Indian Electricity Grid Code
IMD: India Meteorological Department
LGBR: Load Generation Balance Report
NLDC: National Load Dispatch Centre
NR: Northern Region
NRLDC: Northern Regional Load Despatch Centre
NER: North Eastern Region
POSOCO: Power System Operation Corporation Ltd.
PPC: Power Plant Controller
PV: Photo Voltaic
RRAS: Reserve Regulation Ancillary Services
RE: Renewable Energy
RSD: Reserve Shutdown
REMC: Renewable Energy Management Centre
RLDC: Regional Load Dispatch Centre
SCED: Security Constrained Economic Despatch
SLDC: State Load Dispatch Centre
SR: Southern Region
SCADA: Supervisory Control and Data Acquisition
SIL: Surge Impedance Loading
STATCOM: Static Synchronous compensator
SVC: Static VAR Compensator
WR: Western Region
WRLDC: Western Regional Load Despatch Centre
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 6 of 99
Executive Summary
India will be experiencing annular solar eclipse on 21st June 2020. Annularity will be visible in
the states of Rajasthan, Punjab, Haryana, Himachal Pradesh, Uttarakhand with maximum
obscuration1 of around 99% and other parts of country will experience partial solar eclipse.
The annular solar eclipse will begin at 09:56 AM IST at Dwarka, Gujarat and will end at 14:29
PM IST at Dibrugarh, Assam. The path of annularity is as shown in the Figure.1
Figure 1: Path of annular solar eclipse on 21st June 2020
During solar eclipse the Sun is partially/fully covered by the Moon, as a result there will be
reduction in solar irradiance and hence corresponding reduction in power generation from
1 Eclipse Obscuration - Eclipse obscuration is the fraction of the Sun’s area occulted by the Moon. It should not be confused with eclipse magnitude, which is the fraction of the Sun’s diameter occulted by the Moon. Eclipse obscuration may be expressed as either a percentage or a decimal fraction (e.g., 50% or 0.50).
New Delhi 93.8 %
Kolkata 65.5 %
Bangalore 36.2 %
Mumbai 62.1 %
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 7 of 99
solar PV cells. As on 31st March 2020, with installed capacity of 34.6 GW 2 solar PV constitutes
9% of total installed generation capacity of Indian grid. Electricity Grids with such a significant
penetration of solar capacity will be adversely impacted by astronomical events such as solar
eclipse, due to variation in solar generation (reduction followed by rise in generation) and
associated large ramp rates. Maintaining load generation balance and system voltages within
pre-specified IEGC band in the grid are the important tasks of system operator during solar
eclipse. Variation of solar generation disturbs load generation balance (LGB) leading to
deviation of grid frequency from the nominal and the same needs to be maintained by flexing
fast ramping sources like Hydro and Gas generating stations. Low generation from solar power
parks results in high voltages at pooling substations, which needs to be maintained by timely
switching of Reactors/ Transmission lines. Meticulous planning exercise involving following
steps is required for mitigating the impact and maintaining grid stability.
1. Assessment of eclipse impact on solar power generation
a. Irradiance data of previous solar eclipse(26th December 2019) for various solar
parks were analysed to understand the impact of solar eclipse on irradiance w.r.t
% of obscuration. This data along with solar installed capacity growth and solar
generation data of March 2019/June 2019 and March 2020 is used for assessing
the impact. As onset of monsoon is expected on June 1st, weather at some of the
solar park sites in the country may be cloudy on the eclipse day and this will also
play important role for assessing the impact. However, by assessing the impact
w.r.t clear sky, system operators are actually preparing for worst possible
scenario. Reassessment of the impact 2 or 3 days prior to eclipse day would
provide accurate impact.
2. Electricity demand forecast for the period
a. From previous eclipse day demand pattern, it is observed that electricity demand
during the eclipse period will be less compared to normal day due to suspension
of some of the activities during this period. After end of the eclipse there may be
sudden rise in demand due to restarting of human activities. 21st June 2020 being
a Sunday demand would be 3-4 % lower on all India basis compared to a working
2 State wise installed capacity of grid Interactive Renewable power as on 31st March 2020 https://mnre.gov.in/the-ministry/physical-progress
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 8 of 99
day. Demand for eclipse day is forecasted based on previous eclipse experience
and conditions prevailing in the grid during June.
3. Operation planning for maintaining load generation balance (LGB) in the grid
a. Planning of fast ramping sources like Hydro and Gas for compensating the
variations in solar generation.
4. Maintaining the voltages at pooling substations.
a. Switching of bus/line reactors at pooling stations and nearby substations
b. Ensuring that STATCOMs, SVCs are in service and put in voltage control mode
c. Switching of transmission lines if required further
5. Coordination across different utilities of the power system
Solar eclipse 21st June 2020 at a glance:
Parameters Values Type of eclipse/date Annular /21st June 2020 Solar eclipse start time (For India) 09:56 AM (Dwarka) Maximum eclipse time 11:50 AM Solar eclipse end time (For India) 14:29 PM (Dibrugarh, Assam) Visibility of annularity Northern part of India Maximum % of Obscuration 98.66% (Chamoli, Uttarakhand)
All India estimated solar generation reduction at the time of maximum solar eclipse w.r.t. normal day (assuming clear sky conditions)
11943 MW at 11:50 AM
Northern Region estimated solar generation reduction at the time of maximum solar eclipse w.r.t. normal day (assuming clear sky conditions)
4514 MW at 11:47 AM
Western Region estimated solar generation reduction at the time of maximum solar eclipse w.r.t. normal day (assuming clear sky conditions)
2720 MW at 11:50 AM
Southern Region estimated solar generation reduction at the time of maximum solar eclipse w.r.t. normal day (assuming clear sky conditions)
4721 MW at 11:50 AM
All India average solar generation ramp down rate 102 MW/Minute
All India average solar generation ramp up rate 104 MW/Minute
* Solar eclipse impact assessment is done by assuming clear sky conditions which is the worst
possible scenario. June being a monsoon season in India, solar generation is likely to be
impacted by cloud cover on solar eclipse day.
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 9 of 99
Chapter - 1 : Annular eclipse- 21.06.2020
On 21st June 2020, our country will be experiencing annular eclipse, annularity will be visible
in Northern states like Rajasthan, New Delhi, Punjab, Western Uttar Pradesh and Uttarakhand.
Rest of the country will be experiencing partial eclipse of Sun. The annular eclipse will begin at
09:56 AM IST at Dwarka, Gujarat and will end at 14:29 PM IST at Dibrugarh, Assam. This large
annular eclipse will cover over 99% of the sun, lasts for 38 seconds at the point of maximum
eclipse, creating a narrow path of 21 km wide.
The solar eclipse start time, end time and the maximum obscuration for various locations are
obtained from Positional Astronomy Centre, Indian Metrological Department3. From this data
source, 85 locations data for partial eclipse and six locations data for annular eclipse has been
captured throughout the country. For each state, the available location nearest to the
geographical location of the major solar plants have been selected. Details of such locations are
attached at Annexure-I. Further, Figure 2 and 3 shows the path of annular solar eclipse of 21st
June 2020 and eclipse beginning & ending time across the country respectively.
Details of obscuration (%), eclipse start time, maximum eclipse time and end time in major
cities of India are given below: -
S. No. City Obscuration
(%)
Eclipse
Start Time
Maximum
Eclipse Time
Eclipse End
Time
1 New Delhi 93.8 10:20 12:01 13:48
2 Ahmedabad 77.2 10:03 11:42 13:32
3 Mumbai 62.1 10:00 11:37 13:27
4 Kolkata 65.5 10:46 12:35 14:17
5 Hyderabad 50.3 10:14 11:55 13:44
6 Bengaluru 36.5 10:13 11:47 13:31
7 Chennai 34.2 10:22 11:59 13:41
8 Trivandrum 23.2 10:14 11:40 13:15
Table 1 : Details of obscuration( %) in major cities of India
3 The Partial and Annular eclipse start, end time and the maximum obscuration location: http://www.packolkata.gov.in/eclipse.php
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 10 of 99
4
Figure 2: Annular solar eclipse of June 21, 2020
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 11 of 99
5
Figure 3: Solar Eclipse - Beginning and Ending time
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 14 of 99
7
Figure 5: Advance of southwest monsoon 2020
As per above forecast by IMD southwest monsoon enters India by 1st June and hence the
probability of sky being clear at solar park locations of Southern Region and Western Region
on 21st June 2020 is less. However, clear sky conditions may prevail on 21st June 2020 in
Northern Region.
3.1 Analysis of impact of monsoon (weather) on solar generation in June 2019
To observe the impact of weather on solar generation, data for the month of June 2019 has been
analysed. Three sets of data have been considered for analysis purpose.
1) Average solar generation of 5 to 6 clear sky days in the month of June 19
7 Image Source: Press release by IMD on Advance of southwest monsoon into south Andaman Sea https://mausam.imd.gov.in/backend/assets/press_release_pdf/PRESS_RELEASE_17_May_20202.pdf
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 18 of 99
4. Based on the data, reduction in solar generation from Mar-19 and June-19 is observed
due to temperature and cloud cover. From this reduction factor has been calculated
between March-19 to June-19.
5. Further, growth factor (for accounting of growth in solar installed capacity) has been
calculated between June-19 to March-20 to scale up solar generation to tune of Mar-20
with time shift.
6. Above anticipated generation has been scaled up and scaled down with a factor between
June-19 to March-20 and June-19 to March-19 to obtain true generation of June’20.
7. The obscuration of major solar plant of each state and ISTS solar plants has been taken
for calculation.
8. For estimating the impact on state wise solar generation mean obscuration of solar
plants located in the state has been considered and for ISTS generators plant wise
available obscuration has been considered. The details of solar eclipse start time,
maximum time, end time and % of obscuration for states and ISTS connected solar
plants are tabulated below: -
State/ISTS
Connected Solar
plants
Solar eclipse
start time
Maximum
eclipse
time
End of Solar
eclipse time
Obscuration
(%)
Andhra Pradesh 10:14:47 11:52:47 13:38:52 42%
Karnataka 10:09:24 11:45:30 13:32:04 43 %
Tamil Nadu 10:17:27 11:47:18 13:25:49 27%
Telangana 10:16:04 11:57:46 13:46:09 52%
Pavagada Solar Park
(ISTS Connected) 10:11:38 11:47:49 13:33:40 40%
NP Kunta Solar Park
(ISTS connected) 10:15:16 11:52:14 13:37:21 39%
Gujarat 10:01:41 11:38:46 13:28:30 80%
Maharashtra 10:07:50 11:47:22 13:37:13 60%
Madhya Pradesh 10:12:14 11:54:01 13:43:58 76%
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 19 of 99
State/ISTS
Connected Solar
plants
Solar eclipse
start time
Maximum
eclipse
time
End of Solar
eclipse time
Obscuration
(%)
RUMS
(ISTS connected) 10:26:21 12:12:34 14:00:08 75%
Rajasthan 10:09:07 11:47:04 13:34:54 94%
Punjab 10:18:22 11:58:03 13:44:06 98%
Uttar Pradesh 10:23:00 12:08:00 13:56:00 80%
Solar plants at Bhadla (ISTS connected)
10:08:11 11:45:39 13:33:23 94%
Solar plant at Bikaner (ISTS connected)
10:11:52 11:50:22 13:37:42 96%
Table 2: Details of % obscuration for State and ISTS connected solar plants
9. Generation of solar plant in each state has been reduced linearly based on percentage of
obscuration, start and end timings of eclipse. At the time of maximum obscuration of
eclipse, the generation has been considered minimum and in proportion to obscuration.
10. After maximum solar eclipse, generation from solar plants have been increased linearly
based on solar eclipse obscuration and time.
11. Further, based on the experience from previous solar eclipse, for the solar plants or
states which are falling in path of annularity or more than 80 % obscuration, generation
has been reduced by 3% for initial 10 % of obscuration and then generation has been
reduced linearly till time of maximum solar eclipse occurred. After maximum solar
eclipse, generation from solar plant has been increased linearly and for last 10 % of
obscuration only 3 % of generation has been increased.
12. Solar plant or state which are comings in path of partial eclipse or less than 80 %
obscuration, generation has been reduced linearly by 3% for initial 15 % of obscuration
and after that generation has been reduced linearly till the time of maximum solar
eclipse occurred. After maximum solar eclipse, generation from solar plant is increased
linearly and for last 15% of obscuration 3 % of generation only increased.
Based on the above methodology, solar generation has been estimated for the solar rich
states as well as ISTS connected solar generators separately and added to arrive at regional
and all India solar generation.
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 20 of 99
Figure 8 shows all India expected feed-in from solar power plants on 21st June 2020 considering
clear sky conditions, with and without solar eclipse.
Figure 8: All India estimated solar generation on 21st June 2020
It is estimated that eclipse would lead to reduction of all India solar generation by
approximately 11943 MW at maximum obscuration time i.e. 11:50 hrs and total estimated
reduction in energy would be 20 MU w.r.t. a normal day. All India solar generation will start
reducing from 17315 MW at 10:02 hrs to 8415 MW at 11:50 hrs with average ramp down rate
is 102 MW/Minute and after the maximum eclipse, the solar generation will increase from 8415
MW at 11:50 hrs to 18777 MW at 13:58 hrs with average ramp rate of 104 MW/Minute.
During initial period, approximately 8900 MW of solar generation will reduce in very short span
of time i.e 1:48 hrs and after maximum eclipse, it will increase by 10362 MW within 2:08 hrs.
This variation in solar generation will pose serious threat to system security and challenge to
system operators to maintain load and generation balance during the eclipse period i.e. 09:56
hrs (Dwarka) to 14:29 hrs (Dibrugarh).
To maintain the load generation balance during solar eclipse period, 11943 MW generation
from other sources i.e Thermal, Hydro and Gas is required to be ramped up during reduction of
solar generation time and after maximum solar eclipse, the generation from other sources is
required to be ramped down in line with the variations in solar generation.
17315 MW at 10:02 hrs
8415 MW at 11:50 hrs
18777 MW at 13:58hrs
0
5000
10000
15000
20000
5:4
6
6:1
7
6:4
8
7:1
9
7:5
0
8:2
1
8:5
2
9:2
3
9:5
4
10
:25
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:56
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:27
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:58
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:33
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:04
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:35
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:37
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:08
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:39
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:10
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:41
19
:12
Sola
r G
ener
atio
n in
MW
Time
All India estimated solar generation on 21st June 2020 Generation during clear sky condition Estimated generation during solar eclipse Difference
11943 MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 21 of 99
All India solar generation ramp rate during solar eclipse under clear sky condition is shown in
figure 9. It is estimated that average solar generation ramp down rate would be around 102
MW per minute for 1 hour 48 minutes and ramp up rate would be 104 MW per minute for 2
hours and 8 minutes. The estimated maximum solar generation ramp down rate is 184
MW/minute at 11:25 hrs and maximum ramp up rate is 186 MW/minute at 13:02 hrs.
Figure 9: All India normal vs estimated solar generation ramp rate on 21st June 2020
Average solar generation ramp rate of State and ISTS connected solar generation is summarised
below: -
Table 3: Average solar generation ramp rate of State & ISTS connected solar on 21st June 2020
-184
186
-230
-130
-30
70
170
5:4
66
:16
6:4
67
:16
7:4
68
:16
8:4
69
:16
9:4
61
0:1
61
0:4
61
1:1
61
1:4
61
2:1
61
2:4
61
3:1
61
3:4
61
4:1
61
4:4
61
5:1
61
5:4
61
6:1
61
6:4
61
7:1
61
7:4
61
8:1
61
8:4
61
9:1
6
MW
/Min
ute
Time
All India Solar Generation Ramp Rate
Actual ramp rate during clear sky condition Estimated ramp rate during solar eclipse
State/ISTS connected
solar power plants
Average solar generation
ramp down rate MW/
Minute
Average solar generation
ramp up rate MW/Minute
Andhra Pradesh 8 08 Karnataka 10 09 Tamil Nadu 05 07 Telangana 09 09 Gujarat 11 12 Madhya Pradesh 07 07 Maharashtra 03 04 Rajasthan 19 20 Punjab 04 04 Uttar Pradesh 03 03 SR ISTS connected solar 08 08 WR ISTS connected solar 04 04 NR ISTS connected solar 15 14
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 22 of 99
Region, State and ISTS connected solar generation ramp rate for per minute is given as per Annexure III. Figure 10 shows expected feed-in from solar in Northern Region on 21st June 2020 under clear
sky conditions, with and without solar eclipse
Figure 10: Northern Region estimated solar generation on 21st June 2020
The states of Rajasthan, New Delhi, Punjab, Western Uttar Pradesh and Uttarakhand in
Northern Region will observe annular solar eclipse. Rajasthan is renewable rich state and major
solar plants of Northern Region are located in this state. In Northern Region, Punjab will
observe maximum obscuration of 98.77 % followed by Rajasthan of 95 % then Uttar Pradesh
of 80%. It is estimated that solar generation reduction in Northern region is likely to be 4514
MW at the time of maximum obscuration w.r.t. normal day. During the eclipse, solar generation
in Northern region will start reducing from 4194 MW at 10:09 hrs to 465 MW at 11:47 hrs with
average ramp down rate of 40MW/Minute and after the maximum eclipse is over, the solar
generation will increase from 468 MW at 11:48 hrs to 4851 MW at 13:51 hrs with average
ramp up rate of 40 MW /Minute .
4194 MW at 10:09 hrs
465 MW at 11:47 hrs
4851 MW at 13:51 hrs
0
1000
2000
3000
4000
5000
6000
05
:46
06
:16
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:46
07
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:46
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:16
18
:46
19
:16
Sola
r G
ener
atio
n in
MW
Time
Northern Region
Generation during clear sky condition Estimated generation during solar eclipse Difference
4514 MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 23 of 99
The expected maximum solar generation reduction in Rajasthan, Punjab, Uttar Pradesh and
ISTS connected solar plants would be 2180 MW, 479MW, 368 MW and 1612 MW respectively
at the time of maximum obscuration.
Figure 11 shows expected feed-in from solar in Western Region on 21st June 2020 under clear
sky conditions, with and without solar eclipse
Figure 11: Western Region estimated solar generation on 21st June 2020
The states of Gujarat, Maharashtra and Madhya Pradesh in Western Region will observe partial
solar eclipse. Gujarat will observe 80 % of obscuration followed by Madhya Pradesh of 76 %
and then Maharashtra of 60 % obscuration. The estimated reduction of solar generation in
Western Region during solar eclipse is likely to be 2720 MW at time of maximum obscuration
i.e. 11:50 hrs. w.r.t normal day. During the eclipse , solar generation in Western Region will
reduce from 3233 MW at 10:02 hrs to 1249 MW at 11:50 hrs with average ramp down rate of
21 MW/ Minute and after maximum obscuration ,solar generation will start increasing from
1249 MW at11:50 hrs to 3683 MW at 13:58 hrs with average ramp up rate of 22 MW/Minute.
3233 MW at 10:02 hrs
1249 MW at 11:50 hrs
3683 MW at 13:58 hrs
0
500
1000
1500
2000
2500
3000
3500
4000
4500
06
:01
06
:31
07
:01
07
:31
08
:01
08
:31
09
:01
09
:31
10
:01
10
:31
11
:01
11
:31
12
:01
12
:31
13
:01
13
:31
14
:01
14
:31
15
:01
15
:31
16
:01
16
:31
17
:01
17
:31
18
:01
18
:31
19
:01
Sola
r G
ener
atio
n in
MW
Time
Western Region
Generation during clear sky condition Estimated generation during solar eclipse Difference
2720 MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 24 of 99
It is estimated that maximum reduction in solar generation w.r.t. normal day in the states of
Gujarat, Maharashtra and Madhya Pradesh would be 1239 MW at 11:39 hrs, 339 MW at 11:50
hrs and 831 at 11:54 hrs respectively.
The expected total reduction in solar generation from ISTS connected solar plants (Mahindra,
Arisun and ACME) would be 539 MW.
Figure 12 shows expected feed-in from solar in Southern Region on 21st June 2020 under clear
sky conditions, with and without solar eclipse.
Figure 12: Southern Region estimated solar generation on 21st June 2020
Southern part of India will observe partial solar eclipse. As on 31st March 2020, 54 % of all
India’s solar installed capacity is situated in Southern Region. The major solar plants of
Southern Region are located in states of Andhra Pradesh, Karnataka, Tamil Nadu and Telangana
and mean of obscuration at these states are 42%, 43%, 27% and 50% respectively.
It is estimated that reduction in Southern Region solar generation would be 4721 MW at the
time of maximum solar eclipse i.e 11:50 hrs w.r.t. normal day. During the eclipse , the solar
generation in Southern Region is expected to decrease from 10234 MW at 10:09 hrs to 6692
10234 MW at 10:09 hrs
6692 MW at 11:50 hrs
10555 MW at 13:44 hrs
0
2000
4000
6000
8000
10000
12000
14000
05
:46
06
:18
06
:50
07
:22
07
:54
08
:26
08
:58
09
:30
10
:02
10
:34
11
:06
11
:38
12
:10
12
:42
13
:14
13
:46
14
:18
14
:50
15
:22
15
:54
16
:26
16
:58
17
:30
18
:02
18
:34
19
:06
Sola
r G
ener
atio
n i
n M
W
Time
Southern Region
Generation during clear sky condition Estimated generation during solar eclipse Difference
4721 MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 25 of 99
MW at 11:50 hrs with average ramp down rate of 40 MW /Minute and after maximum eclipse ,
solar generation will start increasing from 6692 MW at 11:50 hrs to 10555 MW at 13:44 hrs
with average ramp up rate of 42 MW/Minute.
The expected reduction in solar generation from the state of Andhra Pradesh, Karnataka, Tamil
Nadu and Telangana would be 952 MW,1119 MW, 526 MW and 1147 MW at time of maximum
solar eclipse respectively.
The expected total reduction in solar generation from ISTS connected solar plants (Pavagada
and NP Kunta) would be 1164 MW.
State and ISTS connected solar expected feed-in from solar on 21st June 2020 under clear sky
conditions, with and without solar eclipse is detailed below: -
Figure 13: Rajasthan estimated solar generation on 21st June 2020
1914 MW at 10:09 hrs
139 MW at 11:47 hrs
2290 MW at 13:34 hrs
0
500
1000
1500
2000
2500
05
:46
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:48
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:54
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:39
18
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19
:12
Sola
r G
ener
atio
n in
MW
Time
Rajasthan
Generation during clear sky condition Estimated generation during solar eclipse Difference
2180 MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 26 of 99
Figure 14: Punjab estimated solar generation on 21st June 2020
Figure 15: Uttar Pradesh estimated solar generation on 21st June 2020
432 MW at 10:18 hrs
7 MW at 11:58 hrs
472 MW at 13:47 hrs
0
100
200
300
400
500
600
05
:46
06
:16
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:16
13
:46
14
:16
14
:46
15
:16
15
:46
16
:16
16
:46
17
:16
17
:46
18
:16
18
:46
19
:16
Sola
r G
ener
atio
n in
MW
Time
Punjab
Generation during clear sky condition Estimated generation during solar eclipse Difference
479 MW
418 MW at 10:23 hrs
92 MW at 12:08 hrs
421 MW at 13:51 hrs
0
50
100
150
200
250
300
350
400
450
500
05
:46
06
:16
06
:46
07
:16
07
:46
08
:16
08
:46
09
:16
09
:46
10
:16
10
:46
11
:16
11
:46
12
:16
12
:46
13
:16
13
:46
14
:16
14
:46
15
:16
15
:46
16
:16
16
:46
17
:16
17
:46
18
:16
18
:46
19
:16
Sola
r G
ener
atio
n in
MW
Time
Uttar Pradesh
Generation during clear sky condition Estimated generation during solar eclipse Difference
368 MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 27 of 99
Figure 16: Estimated solar generation connected to ISTS in Northern Region
Figure 17: Gujarat estimated solar generation on 21st June 2020
1450 MW at 10:09 hrs
107 MWat 11:47 hrs
1716 MW at 13:34 hrs
0
500
1000
1500
2000
05
:46
06
:17
06
:48
07
:19
07
:50
08
:21
08
:52
09
:23
09
:54
10
:25
10
:56
11
:27
11
:58
12
:29
13
:00
13
:31
14
:02
14
:33
15
:04
15
:35
16
:06
16
:37
17
:08
17
:39
18
:10
18
:41
19
:12
Sola
r G
ener
atio
n in
MW
Time
ISTS Connected Solar Generation in Northern Region
Generation during clear sky condition Estimated generation during solar eclipse Difference
1612 MW
1217 MW at 10:02 hrs
306 MW at 11:39 hrs
1572 MW at 13:27 hrs
0
400
800
1200
1600
2000
05
:46
06
:17
06
:48
07
:19
07
:50
08
:21
08
:52
09
:23
09
:54
10
:25
10
:56
11
:27
11
:58
12
:29
13
:00
13
:31
14
:02
14
:33
15
:04
15
:35
16
:06
16
:37
17
:08
17
:39
18
:10
18
:41
19
:12
Sola
r G
ener
atio
n in
MW
Time
Gujarat
Generation during clear sky condition Estimated generation during solar eclipse Difference
1223 MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 28 of 99
Figure 18: Maharashtra estimated solar generation on 21st June 2020
Figure 19: Madhya Pradesh estimated solar generation on 21st June 2020
443 MW at 10:07 hrs
226 MW at 11:47 MW
607 MW at 13:37 hrs
0
100
200
300
400
500
600
700
05
:46
06
:17
06
:48
07
:19
07
:50
08
:21
08
:52
09
:23
09
:54
10
:25
10
:56
11
:27
11
:58
12
:29
13
:00
13
:31
14
:02
14
:33
15
:04
15
:35
16
:06
16
:37
17
:08
17
:39
18
:10
18
:41
19
:12
Sola
r G
ener
atio
n in
MW
Time
Maharashtra
Generation during clear sky condition Estimated generation during solar eclipse Difference
339 MW
968 MW at 10:12 hrs
262 MW at 11:54 hrs
993 MW at 13:44 hrs
0
200
400
600
800
1000
1200
05
:46
06
:17
06
:48
07
:19
07
:50
08
:21
08
:52
09
:23
09
:54
10
:25
10
:56
11
:27
11
:58
12
:29
13
:00
13
:31
14
:02
14
:33
15
:04
15
:35
16
:06
16
:37
17
:08
17
:39
18
:10
18
:41
19
:12
Sola
r G
ener
atio
n in
MW
Time
Madhya Pradesh
Generation during clear sky condition Estimated generation during solar eclipse Difference
831 MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 29 of 99
Figure 20: Chhattisgarh estimated solar generation on 21st June 2020
Figure 21: Estimated solar generation connected to ISTS in Western Region
24 MW at 10:23 hrs
10 MW at 12:05 hrs
23 MW at 13:56 hrs
0
5
10
15
20
25
30
05
:46
06
:16
06
:46
07
:16
07
:46
08
:16
08
:46
09
:16
09
:46
10
:16
10
:46
11
:16
11
:46
12
:16
12
:46
13
:16
13
:46
14
:16
14
:46
15
:16
15
:46
16
:16
16
:46
17
:16
17
:46
18
:16
18
:46
19
:16
Sola
r G
ener
atio
n in
MW
Time
Chhattisgarh
Generation during clear sky condition Estimated generation during solar eclipse Difference
14 MW
654 MW at 10:26 hrs
180 MW at 12:12 hrs
605 MW at 13:58 hrs
-100
0
100
200
300
400
500
600
700
800
05
:46
06
:17
06
:48
07
:19
07
:50
08
:21
08
:52
09
:23
09
:54
10
:25
10
:56
11
:27
11
:58
12
:29
13
:00
13
:31
14
:02
14
:33
15
:04
15
:35
16
:06
16
:37
17
:08
17
:39
18
:10
18
:41
19
:12
Sola
r G
ener
atio
n in
MW
Time
ISTS Connected Solar Generation in Western Region
Generation during clear sky condition Estimated generation during solar eclipse Difference
539 MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 30 of 99
Figure 22: Andhra Pradesh estimated solar generation on 21st June 2020
Figure 23: Karnataka estimated solar generation on 21st June 2020
1960 MW at 10:15 hrs
1262 MW at 11:56 hrs
2040 MW at 13:39 hrs
0
500
1000
1500
2000
2500
05
:46
06
:17
06
:48
07
:19
07
:50
08
:21
08
:52
09
:23
09
:54
10
:25
10
:56
11
:27
11
:58
12
:29
13
:00
13
:31
14
:02
14
:33
15
:04
15
:35
16
:06
16
:37
17
:08
17
:39
18
:10
18
:41
19
:12
Sola
r G
ener
atio
n in
MW
Time
Andhra Pradesh
Generation during clear sky condition Estimated generation during solar eclipse Difference
952 MW
2250 MW at 10:09 hrs
1424 MW at 11:48 hrs
2346 MW at 13:32 hrs
0
500
1000
1500
2000
2500
3000
05
:46
06
:17
06
:48
07
:19
07
:50
08
:21
08
:52
09
:23
09
:54
10
:25
10
:56
11
:27
11
:58
12
:29
13
:00
13
:31
14
:02
14
:33
15
:04
15
:35
16
:06
16
:37
17
:08
17
:39
18
:10
18
:41
19
:12
Sola
r G
ener
atio
n in
MW
Time
Karnataka
Generation during clear sky condition Estimated generation during solar eclipse Difference
1119 MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 31 of 99
Figure 24: Tamil Nadu estimated solar generation on 21st June 2020
Figure 25: Telangana estimated solar generation on 21st June 2020
1805 at 10:17 hrs
1354 at 11:50 hrs
1900 MW at 13:26 hrs
0
500
1000
1500
2000
2500
05
:46
06
:16
06
:46
07
:16
07
:46
08
:16
08
:46
09
:16
09
:46
10
:16
10
:46
11
:16
11
:46
12
:16
12
:46
13
:16
13
:46
14
:16
14
:46
15
:16
15
:46
16
:16
16
:46
17
:16
17
:46
18
:16
18
:46
19
:16
Sola
r G
ener
atio
n in
MW
Time
Tamil Nadu
Generation during clear sky condition Estimated generation during solar eclipse Difference
526 MW
1799 MW at 10:15 hrs
926 MW at 11:53 hrs
1852 MW at 13:44 hrs
0
500
1000
1500
2000
2500
05
:46
06
:16
06
:46
07
:16
07
:46
08
:16
08
:46
09
:16
09
:46
10
:16
10
:46
11
:16
11
:46
12
:16
12
:46
13
:16
13
:46
14
:16
14
:46
15
:16
15
:46
16
:16
16
:46
17
:16
17
:46
18
:16
18
:46
19
:16
Sola
r G
ener
atio
n in
MW
Time
Telangana
Generation during clear sky condition Estimated generation during solar eclipse Difference
1047 MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 32 of 99
Figure 26: Estimated solar generation connected to ISTS in Southern Region
2578 MW at 10:11 hrs
1703 MW at 11:50 hrs
2598 MW at 11:36 hrs
0
500
1000
1500
2000
2500
3000
3500
05
:46
06
:17
06
:48
07
:19
07
:50
08
:21
08
:52
09
:23
09
:54
10
:25
10
:56
11
:27
11
:58
12
:29
13
:00
13
:31
14
:02
14
:33
15
:04
15
:35
16
:06
16
:37
17
:08
17
:39
18
:10
18
:41
19
:12
Sola
r G
ener
atio
n in
MW
Time
ISTS Connected Solar Generation in Southern Region
Generation during clear sky condition Estimated generation during solar eclipse Difference
1164 MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 33 of 99
Chapter - 5 : Forecasted all India and Regional demand
The pattern of human behavior in India is unique since cultural factors get intertwined with
astronomical events like solar eclipses and lunar eclipses. Majority of the people in India re-
start and undertake a lot of activities as soon as solar eclipse gets over i.e. taking baths, opening
of closed shops, opening of temples, preparation of fresh food which leads to spurt in demand.
India experienced three solar eclipses in the past ten years, first solar eclipse on 22nd July 2009,
followed by 15th January 2010 and then 26th December 2019. During 22nd July event, average
demand reduction in Eastern Region was 4.2% and instantaneous maximum demand reduction
was 7% w.r.t normal day. Eastern Region demand from 21st July 2009 to 23rd July 2009 is given
below: -
Figure 27: Eastern Region demand from 21st July 2009 to 23rd July 2009
The average demand reduction in Southern Region during solar eclipse on 15th January 2010
was 2.5% and instantaneous maximum demand reduction was 5% w.r.t to previous day and
after end of solar eclipse demand increased 3%. Southern Region demand from 14th January
2010 to 16th January 2010 is given below: -
8500
8700
8900
9100
9300
9500
9700
9900
10100
10300
4:0
0:0
0
4:1
5:0
0
4:3
0:0
0
4:4
5:0
0
5:0
0:0
0
5:1
5:0
0
5:3
0:0
0
5:4
5:0
0
6:0
0:0
0
6:1
5:0
0
6:3
0:0
0
6:4
5:0
0
7:0
0:0
0
7:1
5:0
0
7:3
0:0
0
7:4
5:0
0
8:0
0:0
0
8:1
5:0
0
8:3
0:0
0
8:4
5:0
0
9:0
0:0
0
Dem
and
in M
W
Time
Eastern Region Demand
21-07-2009 22-07-2009 23-07-2009
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 34 of 99
Figure 28: Southern Region demand from 14th January 2010 to 16th January 2010
In third annular solar eclipse which was on 26th December 2019, the pattern of demand
variance showed that on an average around 2.4% demand reduced with an instantaneous
maximum demand reduction of 4.2 %. Further, it was observed that all India demand increased
by about 6372 MW i.e. by 3.8 %, when eclipse got over. All India demand from 24th December
2019 to 26th December 2019 is given below: -
Figure 29: All India demand from 24th December 2019 to 26th December 2019
18000
20000
22000
24000
260000
:01
:00
0:5
5:0
0
1:5
0:0
0
2:4
5:0
0
3:4
0:0
0
4:3
5:0
0
5:3
0:0
0
6:2
5:0
0
7:2
0:0
0
8:1
5:0
0
9:1
0:0
0
10
:05
:00
11
:00
:00
11
:55
:00
12
:50
:00
13
:45
:00
14
:40
:00
15
:35
:00
16
:30
:00
17
:25
:00
18
:20
:00
19
:15
:00
20
:10
:00
21
:05
:00
22
:00
:00
22
:55
:00
23
:50
:00
Dem
and
in M
W
Time
Southern Region Demand14-01-2010 15-01-2010 16-01-2010
Average Demand Reduction: 2.5 % Instantaneous maximum reduction in
demand : 5 %
130000
135000
140000
145000
150000
155000
160000
165000
170000
175000
06
:00
06
:20
06
:40
07
:00
07
:20
07
:40
08
:00
08
:20
08
:40
09
:00
09
:20
09
:40
10
:00
10
:20
10
:40
11
:00
11
:20
11
:40
12
:00
12
:20
12
:40
13
:00
Dem
and
in M
W
Time
All India Demand 26.12.2019 25.12.2019 24.12.2019
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 35 of 99
It may be noted that due to announcement of countrywide lockdown due to COVID-19 since
25th March 2020, All India demand reduced by 40-45 GW in the months of March & April 2020.
However, at the time of writing this report lockdown has been relaxed to some extent and
commercial & industrial activities have started leading to increase in demand. If similar
situation prevails in the month of June 2020, then it is expected that all India demand is likely
to be in the range of ~150-155 GW during solar eclipse period on 21st June 2020.
Based on previous solar eclipse events occurrences in India, it is expected that during eclipse
on 21st June 2020, there would be depression in demand due to human behaviour. However,
due to countrywide lockdown, this time reduction and increase in demand could be less
compared to previous eclipses because temples, malls and small commercial shops are already
closed and heating load will not be there in Southern Region. Therefore, slowing down human
activity in terms of cooking, agriculture and other day to day activities would lead to decrease
and increase in power consumption.
In view of the above, it is expected that all India average demand may reduce by 2-2.5% with
instantaneous maximum reduction 3-3.5 % and after eclipse it may increase by the same
amount.
The estimated all India and region wise demand for 21st June 2020 is given below: -
Figure 30: All India estimated demand on 21st June 2020
115000
125000
135000
145000
155000
165000
175000
00
:55
01
:55
02
:55
03
:55
04
:55
05
:55
06
:55
07
:55
08
:55
09
:55
10
:55
11
:55
12
:55
13
:55
14
:55
15
:55
16
:55
17
:55
18
:55
19
:55
20
:55
21
:55
22
:55
Dem
and
in M
W
Time
All India Demand
2018 2019 2020(Forecasted)
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 36 of 99
Figure 31: Northern Region estimated demand on 21st June 2020
Figure 32: Western Region estimated demand on 21st June 2020
35000
40000
45000
50000
55000
60000
650000
0:5
0
01
:45
02
:40
03
:35
04
:30
05
:25
06
:20
07
:15
08
:10
09
:05
10
:00
10
:55
11
:50
12
:45
13
:40
14
:35
15
:30
16
:25
17
:20
18
:15
19
:10
20
:05
21
:00
21
:55
22
:50
23
:45
Dem
and
in M
W
Time
Northern Region Demand
2018 2019 2020(Forecasted)
30000
35000
40000
45000
50000
00
:50
01
:45
02
:40
03
:35
04
:30
05
:25
06
:20
07
:15
08
:10
09
:05
10
:00
10
:55
11
:50
12
:45
13
:40
14
:35
15
:30
16
:25
17
:20
18
:15
19
:10
20
:05
21
:00
21
:55
22
:50
23
:45
Dem
and
in M
W
Time
Western Region Demand
2018 2019 2020(Forecasted)
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 37 of 99
Figure 33: Southern Region estimated demand on 21st June 2020
Figure 34: Eastern Region estimated demand on 21st June 2020
19000
24000
29000
34000
39000
44000
00
:00
00
:55
01
:50
02
:45
03
:40
04
:35
05
:30
06
:25
07
:20
08
:15
09
:10
10
:05
11
:00
11
:55
12
:50
13
:45
14
:40
15
:35
16
:30
17
:25
18
:20
19
:15
20
:10
21
:05
22
:00
22
:55
23
:50
Dem
and
in M
W
Time
Southern Region Demand
2018 2019 2020(Forecasted)
9000
11000
13000
15000
17000
19000
21000
23000
25000
00
:50
01
:45
02
:40
03
:35
04
:30
05
:25
06
:20
07
:15
08
:10
09
:05
10
:00
10
:55
11
:50
12
:45
13
:40
14
:35
15
:30
16
:25
17
:20
18
:15
19
:10
20
:05
21
:00
21
:55
22
:50
23
:45
Dem
and
in M
W
Time
Eastern Region Demand
2018 2019 2020(Forecasted)
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 38 of 99
Figure 35 : North Eastern Region estimated demand on 21st June 2020
700
900
1100
1300
1500
1700
1900
2100
2300
2500
27000
0:4
00
1:2
50
2:1
00
2:5
50
3:4
00
4:2
50
5:1
00
5:5
50
6:4
00
7:2
50
8:1
00
8:5
50
9:4
01
0:2
51
1:1
01
1:5
51
2:4
01
3:2
51
4:1
01
4:5
51
5:4
01
6:2
51
7:1
01
7:5
51
8:4
01
9:2
52
0:1
02
0:5
52
1:4
02
2:2
52
3:1
0
De
ma
nd
in
MW
Time
North Eastern Region Demand
2018 2019 2020(Forecasted)
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 39 of 99
Chapter - 6 : System reliability study for 21st June 2020 solar eclipse
As per the forecast, it is estimated that the solar eclipse would lead to reduction in all India solar
generation from 17315MW at 10:02 hrs to 8415 MW at 11:50 hrs. Subsequently, the generation
will start increasing achieving normal pattern by 13:58 hrs. The average ramp down and ramp
uprate is expected to be 102MW/Minute and 104 MW/Minute respectively. Region wise details
are as under: -
S. No.
Region
Forecasted Solar Generation on 21st June
(MW) Difference
(MW) Difference
(MW)
Forecasted solar
generation at 11:50 hrs in case
of clear sky (D)
Difference (MW)
10:02 hrs
11:50 hrs
13:58 hrs (B-A) (C-B) (D-B)
(A) (B) (C)
1 Northern 4076 474 4834 -3602 4360 4977 4503
2 Western 3233 1249 3685 -1984 2436 3968 2719
3 Southern 10006 6692 10260 -3314 3568 11413 4721
4 All India 17315 8415 18779 -8900 10364 20358 11943
Table 4: All India and Region wise estimated solar generation
The solar generation in above mentioned regions will have to be replaced with conventional
generation and this may affect the normal inter-regional flow pattern. The inter-regional drawls
on 23rd June 2019 (Sunday during the eclipse week last year) given below provide an idea of
the margin that will be available on inter-regional corridors on 21st June 2020.
S.
No.
Exporting
Region
Importing
Region
Present
ATC
IR -
23rd
June
2019
10:00
hrs
Margin
IR -
23rd
June
2019
11:50
hrs
Margin
IR -
23rd
June
2019
(Max)
Margin
1 Western Northern 17200 6092 11108 7269 9931 9977 7223
5 Import of NR 22450 9632* 12818 10739* 11711 13983* 8467
6 Import of SR 12900 3760 9140 2543 10357 4800 8100 *includes 500 MW from NER
Table 5: Inter-regional drawls and margin on 23rd June 2019
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 40 of 99
Based on the margins available in inter-regional corridor on 23rd June 2019, the solar
generation reduction of ~4.5 GW is in NR, ~2.7 GW in WR and ~4.7 GW in SR on 21st June 2020
is not expected to cause any constraints in inter-regional corridors.
A power system simulation study has been carried out to analyze the impact of eclipse on
network loadings and voltages. The details are given below.
Assumptions: -
a) All India June 2020 case with updated network and scaled load and generation for 10:00
hrs and 11:50 hrs of 21st June 2020 has been considered for study purpose.
b) The all India demand has been considerably less than the usual demand during the last
02 months due to the countrywide lockdown since 25th March 2020. However, with
gradual relaxation of restrictions during the last few days, the demand has started
picking up.
The demand of following 02 days has been considered to estimate the demand on 21st
June at 10:00 hrs.
• 17th May 2020 – Previous Sunday
• 23rd June 2019 – Sunday during the eclipse week last year
The region-wise demand considered in power system simulation case is given below. The state
wise LGB in the case is at Annexure-IV.
S. No. Region Demand 21st June Demand in Power System Simulation cases
17th May 2020 23rd June 2019 10:00 hrs 11:50 hrs*
1 Northern 42597 51776 50316 51316
2 Western 40618 44565 43865 44865
3 Southern 37294 35897 36603 37103
4 Eastern 15298 16404 16604 17104
5 North Eastern 1542 1819 1710 1710
6 All India 137349 150461 149101 152100
• All figures are in MW for 10:00 hrs
*Usually, 3 GW increase in all India demand is observed between 10:00 hrs to 12:00 hrs.
Table 6: Region wise considered demand in power system simulation study case
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 41 of 99
c) The state and plant wise solar generation considered in the case (10:00 hrs and 11:50
hrs) is enclosed at Annexure-V.
d) The increase in source wise generation from 10:00 hrs to 11:50 hrs (as replacement of
solar generation) is enclosed at Annexure-VI.
Study Results: -
a) Comparison of Inter-regional flows
S. No.
Exporting Region
Importing Region
Present ATC
Base Case
Margin
Eclipse Case
Margin 10:00
hrs 11:50
hrs
1 Western Northern 17200 7200 10000 5790 11410
2 Eastern Northern 5250 1513 3737 1699 3551
3 Western Southern 6950 1452 5498 2138 4812
4 Eastern Southern 5950 3960 1990 4246 1704
5 Western Eastern - 2387 - 1721 -
6 Import of NR 22450 9213* 13237 7989* 14461
7 Import of SR 12900 5412 7488 6384 6516
All figures are in MW *includes 500 MW from NER
Table 7: Inter-regional flow in base case and eclipse case
b) Maximum and minimum voltages at 400 kV level and above observed in the eclipse case
are enclosed at Annexure-VII.
c) Network loadings are observed to be within limits. Except 765 kV Sasan – Vindhyachal
D/C, loading of all 765 kV lines are below 50% of SIL. Further, at 400 kV level, loading of
no major line is observed to be beyond 50% of thermal limit.
d) Following ICTs have been observed as N-1 non-compliant in the eclipse case.
• 2X500 MVA 400/220 kV ICTs at Rajpura (loading 76%)
• 2X500 MVA 400/220 kV ICTs at Deepalpur (loading 66%)
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 42 of 99
e) Voltages at buses near large solar parks are as under: -
S. No.
Station Voltage
Level (kV)
Voltage (kV)
Voltage (kV) Fault Level
Base Case 10:00 hrs
Eclipse Case11:50 hrs
1 Bhadla - PG 400 401 408 18100 MVA,
26.1 KA
2 Bhadla-RS 400 401 407 17046 MVA,
24.6 KA
3 Rewa-PG 400 403 406 8524 MVA, 12.3
KA
4 NP Kunta 400 419 418 18140 MVA,
26.1 KA
5 Pavagada 400 414 415 29574 MVA,
42.6 KA
6 Bhadla-PG 765 781 782 19139 MVA,
14.4 KA
7 Bikaner-PG 765 777 786 28026 MVA,
21.1 KA
Table 8: Voltages at buses near large solar parks
f) Actions to be taken: -
• Suitable Margins in HVDCs towards NR and SR may be kept before start of eclipse and
power order may be modulated proactively. Power order to be maximized during
reduction in solar generation and to be reduced as per requirement while increase in
solar generation.
• SCED to be disabled before the eclipse to keep sufficient margins in inter-regional
corridors and ISGS plants.
• All the bus reactors near solar generating stations to be switched on gradually before
the start of the eclipse and to be taken out as per grid voltage after 12:00 hrs.
• Solar generating plants/inverters may be advised to generate/absorb VARs to maintain
the voltage within permissible limits.
• All other generating stations may also be advised to generate/absorb VARs as per
capability curve.
• STATCOMs, SVCs to be in service in voltage control mode (reference 1 pu).
• Sufficient reserves to be maintained and maximum units to be brought on bar before the
eclipse.
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 43 of 99
Chapter - 7 : Operational Planning
7.1 Northern Region
It is estimated that solar generation reduction in Northern Region is likely to be 4514 MW at
the time of maximum obscuration w.r.t. normal day. During the eclipse, solar generation in
Northern Region will start reducing from 4194 MW at 10:09 hrs to 465 MW at 11:47 hrs with
average ramp down rate of 40 MW/Minute and after the maximum eclipse is over the solar
generation will increase from 468 MW at 11:48 hrs to 4851 MW at 13:51 hrs with average
ramp rate of 40 MW/Minute .
The Northern Region is required to manage the following during eclipse period
1. Managing solar generation reduction & associated ramps from eclipse start to maximum
eclipse time.
2. Managing solar generation increase & associated ramps from maximum eclipse to end
of eclipse.
3. Arranging power from alternate sources for meeting the demand which was generally
met from solar power
The management of anticipated solar reduction and subsequent recovery required high
ramping resources with flexible characteristics. The high ramping resources such as hydro and
gas generators are required to be scheduled during the event.
I. Scheduling of all conventional reserves in Northern Region
The data of reserves available during 20th June-19 to 22nd June-19 in NR ISGS thermal stations
have been analysed and average cold and hot reserves available are shown below: -
Figure 36: Northern Region average cold and hot reserve
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 44 of 99
It is observed from the above plot that average cold reserve and hot reserve were 2162 MW
and 860 MW between 10:00 hrs to 14:00 hrs (while calculating the reserves SCED is ignored).
It is expected that on 21st June 2020, ISGS generators to the tune of 3000-3500 MW would be
under reserve shutdown. Due to less demand in Northern Region, at present Dadri TPS-I, Dadri
TPS-II, Unchahar TPS and ISTPP Jhajjar of NR ISGS thermal units are under reserve shutdown.
Based on the reserve availability before 21st June 2020 bringing of one or two units of coal-
based NR ISGS thermal generators may be considered.
During the period of 20th June 19 to 22nd June19, Gas power plant at Auraiya GPS and Anta GPS
were also under reserve shutdown due to less demand. Following gas based units are likely to
be available on 21st June 2020 for scheduling.
S.NO. STATION EFFECTIVE INSTALLED CAPACITY (MW)
1 DADRI GPS 2X154.51+4x130.19 = 830.00
2 ANTA GPS 2X153.21+3x88.71 = 419.00
3 AURAIYA GPS 2X109.3+4x111.19 = 663.00
TOTAL 1912.00
Table 9: Northern Region ISGS gas based stations
5-minute scheduling from gas-based stations has been done in line with solar generation
reduction during solar eclipse. The maximum 1227 MW has been scheduled from gas based
stations during maximum solar eclipse.
Figure 37: Northern Region gas generation schedule on 21st June 2020
0
200
400
600
800
1000
1200
1400
0
1000
2000
3000
4000
5000
6000
10
:15
10
:25
10
:35
10
:45
10
:55
11
:05
11
:15
11
:25
11
:35
11
:45
11
:55
12
:05
12
:15
12
:25
12
:35
12
:45
12
:55
13
:05
13
:15
13
:25
13
:35
13
:45
Gas
Sch
ed
ule
in M
W
Sola
r G
ener
atio
n in
MW
Time
Northern Region Gas Generation scheduleGeneration during clear sky condition Estimated generation during solar eclipse
Total Schedule of Gas Generation
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 45 of 99
Gas based stations scheduling is done considering open cycle mode of operation. However, on
real time basis based on machines on-Bar in close cycle or open cycle same may be rescheduled.
Plant wise 5-minute schedule for gas-based station is attached at Annexure- VIII
II. Scheduling of Hydro Generation in Northern Region
During the eclipse period, hydro generators may be scheduled to tackle solar generation ramp
down and ramp up. As per figure 38 shown, it is observed that Northern Region total reservoir
level (Energy Content) in MU as on 20th May 2020 is 1279 MU, which is similar to last year’s
reservoir level.
Figure 38: Energy Content (MU) on last day of the month for the years 2018-19 to 2020-21
Hydro stations scheduling has been done based on inflow patterns and dam level for the year
2018 and 2019.Hydro stations having significant margin (Tehri, Koldam, Chamera-I&III,
Dhauliganga, Pong, Parbati-III, 2 machines each in Bhakhra-L&R) have been considered for
optimization. The details of hydro plant are given below: -
0
500
1000
1500
2000
2500
3000
3500
4000
4500
30
th A
pri
l
31
st M
ay
30
th J
un
e
31
st J
uly
31
st A
ug
30
th S
ept
31
st O
ct
30
th N
ov
31
st D
ec
31
st J
an
28
th F
eb
31
st M
arch
Ener
gy C
on
ten
t in
MU
Last day of the month
Reservior levels in MU as on last day of the month for the years 2018-19 to 2020-21
2018-19 2019-20 2020-21 10 Years Average
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 46 of 99
S.NO. STATION EFFECTIVE INSTALLED CAPACITY (MW)
1 TEHRI HPS 4x250 = 1000.00
2 KOLDAM HPS 4x200 = 800.00
3 CHAMERA-I HPS 3x180 = 540.00
4 CHAMERA-III HPS 3x77 = 231.00
5 DHAULIGANGA HPS 4x70 = 280.00
6 PARBATI-III HPS 4x130 = 520.00
7 BHAKHRA-L&R HPS 2x108+3x126+5x157 = 1379.00
8 PONG HPS 6x66 = 396.00
TOTAL 5146.00
Table 10: Northern Region ISGS hydro generating stations
Spillage is anticipated in Major RoR and RoR with pondage plants like NJHEP, Rampur,
Dhulhasti, KWHEP, Salal, Uri-I&II, so these are not considered for optimization.
During start of solar eclipse hydro generation is required to ramp up and subsequently after
maximum solar eclipse, hydro generation needs to be ramped down. The figure 39 shows 5-
minute hydro schedule in line with solar generation reduction. Plant wise 5-minute hydro
scheduling is attached as per Annexure-IX
Figure 39: Northern Region hydro generation schedule on 21st June 2020
0
500
1000
1500
2000
2500
3000
3500
4000
0
1000
2000
3000
4000
5000
6000
10
:15
10
:25
10
:35
10
:45
10
:55
11
:05
11
:15
11
:25
11
:35
11
:45
11
:55
12
:05
12
:15
12
:25
12
:35
12
:45
12
:55
13
:05
13
:15
13
:25
13
:35
13
:45
Hyd
ro S
che
du
le in
MW
Sola
r G
ener
atio
n in
MW
Time
Northern Region Hydro Generation ScheduleGeneration during clear sky condition Estimated generation during solar eclipse
Total Hydro Schedule
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 47 of 99
Following actions are also required to be taken during scheduling of hydro and gas-based
stations
I. All Hydro stations may be advised to operate in FGMO. Further Droop settings of all
hydro stations and gas stations may be reduced to 2-3%. Similarly drop of thermal
stations may also be reduced to 3-4%.
II. Constituents may be requested to freeze their requisitions well in advance say by 09:00
hrs on 21st June 2020 to enable better reserve assessment and RRAS planning by
NRLDC/NLDC in advance.
III. In addition to above, all Gas based stations and some hydro stations will be kept on
minimum load up to around 13:50 hrs on the day of eclipse to enable fast ramping in
case sudden load rise post solar eclipse.
Rajasthan
The expected maximum solar generation reduction in Rajasthan would be 2180 MW during the
eclipse period. Rajasthan has to arrange this power from their available resource. At the peak
of eclipse, all hydro generation may be maximized so that maximum fast ramping hydro
generation would be available for managing solar generation increase after eclipse. The
generation from wind plants should also be properly forecasted and closely monitored during
eclipse period. Rajasthan has following hydro plants that may be scheduled during solar eclipse
period from their available resource to mitigate this effect.
S.NO. STATION EFFECTIVE INSTALLED CAPACITY (MW)
1 MAHI BAJAJ SAGAR 2x25+2x45 = 140.00
2 RANA PRATAP SAGAR 4x43 = 172.00
TOTAL
312.00
Table 11: Rajasthan hydro generating stations
Thermal generation of Rajasthan also needs to be planned in coordination with hydro
generation so that additional support from thermal can be utilized. ISGS Hydro plants may also
be scheduled to further optimize the drawal from the grid.
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 48 of 99
Uttar Pradesh
The expected maximum solar generation reduction in Uttar Pradesh would be 368 MW during
solar eclipse period. Uttar Pradesh has to arrange this power from their available resource. The
list of available Hydro resource from Uttar Pradesh is given below: -
S.NO. STATION EFFECTIVE INSTALLED CAPACITY (MW)
1 RIHAND HPS 6x50 = 300.00
2 OBRA HPS 3x33 = 99.00
3 MATATILA HPS 3x11 = 33.00
4 VISHNUPRAYAG HPS 4x110 = 440.00
5 ALAKNANDA HPS 4x82.50 = 330.00
TOTAL 1202.00
Table 12: Uttar Pradesh hydro generating stations
Uttar Pradesh has to schedule 368 MW power with above available hydro resources. If the
above resource is not available on day of eclipse, then 368 MW will be required to be scheduled
from ISGS hydro plant /thermal /gas or own thermal generations during the eclipse period.
Punjab
The expected maximum solar reduction during solar eclipse period in Punjab would be 479
MW. Punjab has to arrange this power from their available resource. The list of available hydro
resource of Punjab is given below. Punjab is required to schedule 479 MW power from available
hydro resources and if on day of eclipse these resources are not available then same quantum
may be scheduled from ISGS hydro plants.
S.NO. STATION EFFECTIVE INSTALLED CAPACITY (MW)
1 SHANAN HPS 4x15+1x50 = 110.00
2 RANJIT SAGAR HPS 4x150 = 600.00
TOTAL
710.00
Table 13: Punjab hydro generating stations
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 49 of 99
7.2 Western Region
Based on the obscuration factor, provisional forecast of the solar generation with the eclipse
impact has been calculated. Details of maximum % of obscuration and estimated reduction of
solar generation in Western Region on 21st June 2020 are given below: -
State/Region Maximum% of Obscuration Estimated Maximum
Solar Generation
Reduction (MW)
Gujarat 80% 1223
Madhya Pradesh 76% 831
Maharashtra 60% 359
Western Region 68% 2720
Following operations may be planned to balance the load and generation to maintain the
compliance in the grid during solar eclipse.
I. Scheduling of all conventional generation in Western Region As per forecast of solar generation during solar eclipse, maximum reserved required is 2720
MW the same is plotted and shown below: -
Figure 40: Western Region reserve requirement on 21st June 2020
Maximum reserve required is 2720MW. The data of reserves available during 18-June -19 to
25-June-2019 in WR ISGS station is analysed and average reserves available is shown below: -
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 50 of 99
Actual average on-bar reserves available during 10:00 hrs to 14:00 hrs was in the range of
1000MW in ISGS units at regional level. Lower reserve was available due to outage of Gas units
at KAWAS and Gandhar under RSD (less schedule). Also, during June’19, It was also observed
that Gadarwara(800MW) and Solapur(660MW) were kept out on RSD. Therefore, to mitigate
the requirement of reserves of 2720 MW, planning of generating units to be kept on bar for
flexibility. Appropriate planning to keep the units (listed below) in service may be done keeping
the fast response required during the eclipse.
S.NO. STATION EFFECTIVE INSTALLED CAPACITY (MW)
1 KAWAS GPS 4x106+2x116.1 = 656.20
2 GANDHAR GPS 3x144.3+1x224.49 = 657.39
3 MAUDA-I &II 2x500+2x660 = 540.00
4 GADARWARA 1x800 = 800.00
5 KHARGONE 2x660 = 1320.00
6 SOLAPUR 2x660 = 1320.00
7 LARA 2x800 = 1600.00
TOTAL 6893.59
Table 15: Western Region ISGS Gas and Thermal stations
Total SR 9547 6640 2907 Total All India 16580 8255 8064
* In NR, details of connectivity of some small solar plants are not available. Reduction in generation in those plants during eclipse has been considered through increase in demand in respective areas. All figures are in MW
Solar eclipse, 21st June 2020 likely impacts and Preparedness- A report Page 84 of 99
Annexure- VI
Details of Increase in Generation Hydro
Region Plants Increase in generation (MW)
NR
Nathpa Jhakri 0 Karcham 0 Dulhasti 0 Tehri 490 Koldam 770 Chamera I, II & III 770 Rampur 0 Bhakra 450 Pong 400 Parbati I, II & III 520 Sewa-II 0 Dhauliganga 280 Bairasul 0