Deviation Settlement Mechanism (DSM)

Eastern Regional Power Committee, Kolkata-33
S K Pradhan, Assistant Director
Email: shishir.1505@gmail.com, eecom1.erpc@gov.in,
Phone: +91-8249244719

 Actual Generation – Scheduled Generation (For
Generators)
 Total Actual Drawl – Total Scheduled Drawl (For
Beneficiaries)
 Worked out for each 15 min time block
 Based on average frequency of the relevant time block
 Payable for over-drawl/under-injection by buyer/seller
Receivable for under-drawl/over-injection by buyer/seller
ERPC, KOLKATA 2

 Prior to DSM regulation, CERC(UI Charges and Related matters)
Regulation’2009 was in place.
 In the mean time Two Major Grid disturbance occurred back to back
on 30th July’2012 and 31st July’2012 with blackout of NR, ER & NER
regions of India.
 Load of around 48000 MW affected by the grid disturbance.
 Largest power outage in the history by number of people affected.
 GoI appointed a Enquiry committee under the chairmanship of
chairman CEA to study the cause of failure and submit report within
15 days.
ERPC, KOLKATA 3

 Committee submitted its report on 16.08.2012 to GoI with causes of
failures and suggestions to prevent future grid failures.
 Reasons for failure:
Weak inter regional corridor due to multiple outage.
Huge over drawl by NR utilities(UP, Haryana, Rajasthan & Punjab
etc.) and huge under drawl by WR utilities(MP, Maharashtra, Gujrat
etc..)
Inadequate response by SLDCs to the instructions of RLDCs.
ERPC, KOLKATA 4

Suggestions:
 Frequency band needs to be further tightened close to 50 Hz.
 A review of UI mechanism should be carried out in view of its impact on
recent grid disturbances.
 Frequency control through UI may be phased out in a time bound manner.
 Generation reserves/Ancillary services may be used for frequency control.
POSOCO file a petition before CERC for review of UI mechanism while
considering Enquiry Committee suggestions. After detail examination of the
proposal by staffs of commission, CERC issued draft CERC(DSM & Related
matters) regulation’2013 for public and same was implemented w.e.f.
17.02.2014.
ERPC, KOLKATA 5

 Came into force on 17.02.2014
 To maintain grid discipline and grid security.
 Major provisions:
• Frequency band (50.05-49.85 Hz)
• ACP linked Deviation Rate Vector.
• Volume limit for buyer/seller.
• Cap Rate for all Generators.
• Addl. DC for sustained unidirectional deviation.
ERPC, KOLKATA 7

 Frequency band is 50.05 Hz to 49.85 Hz.
 Charges for deviation for each 0.01 Hz step is changing everyday.
 Deviation price vector linked to Daily Average Area Clearing
Price(ACP) in Day Ahead Market of Power Exchange.
 Charges for deviation below 49.85 Hz is fixed at 800p/u, for freq
50.05 Hz and above charges for deviation is 0 p/u.
 Charges for deviation at 50.00 Hz will be Daily Average Area
Clearing Price(ACP) discovered at DAM (Max ceiling being 800 p/u).
 The Day-ahead market price of the Power Exchange having a
market share of 80% or more in energy terms on a daily basis shall
be taken into consideration for linking to the DSM price vector.
 DSM rate vector will have a dynamic slope determined by joining
the identified price points at 50 Hz(daily avg. ACP),frequency below
49.85 (800p/u) and 50.05 Hz (0p/u) on daily basis.
ERPC, KOLKATA 8

Average freq of the time block (Hz) Charges for Deviation
Below Not below Paise/kWh
50.05 0.00
50.05 50.04 1x(P/5)
50.04 50.03 2x(P/5)
------ ------ ------
50.01 50.00 P
50.00 49.99 50.00+15x(P/16)
49.99 49.98 100.00+14x(P/16)
------ ----- ------
49.87 49.86 700.00+2x(P/16)
49.86 49.85 750.00+1x(P/16)
49.85 800.00
ERPC, KOLKATA 9
P=Average Area Clearing Price

E1 E2
Inter
Regional
Cross
Boarder
West Bengal Sikkim Odisha NR
NVVN-
Nepal
Bihar
HVDC
ALIPURDA
R
TSTPS-I SR NVVN-BD
Jharkhand
HVDC
SASARAM
JITPL WR TPTCL
Barh DVC GMRKEL NER
FSTPP-I RANGIT
IND
BARATH
FSTPP-III TEESTA
OPGC_INFI
RM
KHSTPP-I APNRL
DARLIPALI
_INFIRM
KHSTPP-ii
JORETHA
NG LOOP
HEP
NPGC THEP
MPL RB
TEESTA-
III(TUL)
MTPS-II
CHUZACH
EN
BRBCL DIKCHU
NPGC_INFI
RM
ERPC, KOLKATA 10

0.00
100.00
200.00
300.00
400.00
500.00
600.00
700.00
800.00
900.00
49.65
49.66
49.67
49.68
49.69
49.70
49.71
49.72
49.73
49.74
49.75
49.76
49.77
49.78
49.79
49.80
49.81
49.82
49.83
49.84
49.85
49.86
49.87
49.88
49.89
49.90
49.91
49.92
49.93
49.94
49.95
49.96
49.97
49.98
49.99
50.00
50.01
50.02
50.03
50.04
50.05
50.06
50.07
50.08
50.09
50.10
DSMRate(Paisa/Kwh)
Previous DSM Rate Vs Existing DSM Rate
Existing DSM rate
DSM@ACP=0
DSM@ACP=190.467
DSM@ACP=300
DSM@ACP=500
DSM@ACP=800
ACP=190.467, Step of
DSM price vector become uniform
Frequency in Hz
Previous DSM Price Vector Curve DSM Price Vector@ ACP>=800
DSM Price Vector@ACP=0
ERPC, KOLKATA 11
Return
Cap Rate@303.04

ERPC, KOLKATA 12
0
50
100
150
200
250
300
350
400
450
500
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
ACP(paise/kwh)
Jan-19
May-19
Jul-19
Oct-19

ERPC, KOLKATA 13
ERPC, KOLKATA13
DEVIATION
UNDERINJECTION /
OVERDRAWL
OVERINJECTION /
UNDERDRAWL
f < 49.7 Hz f >=50.05
High(DC+ADC)
Payable @824.04p/u
(APM Cap Rate
303.04p/u)
50.05>f >=49.7
DC or DC+ADC Payable
(Cap Rate for APM
303.04p/u)
f < 49.7 Hz 50.1>f >=50.05 f >=50.150.05>f >=49.7
DC Receivable
(Cap Rate for APM
303.04 p/u)
No ADC
DC Receivable
(Cap Rate for
APM 303.04 p/u)
No ADC
No DC
ADC @ 178 p/u
No DC & ADC
No DC & ADC
DC Deviation Charge
ADC  Addl. Deviation Charge
Rate @50Hz =178p/uRate @50Hz =ACP
f < 49.85 Hz 50.05>f >=49.85 f >=50.05 f < 49.85 Hz
High(DC+ADC)
Payable @800 p/u
(Cap Rate for
generators)
DC or DC+ADC Payable
(Cap Rate for
generators)
No DC & ADC
DC Receivable
(Cap Rate for
generators)
No ADC
f >=50.1
No DC
ADC @ Min(ACP,
303.04)
DC Receivable
(Cap Rate for
generators)
No ADC
No DC & ADC
50.05>f >=49.85 50.1>f >=50.05

1. Over injection/Under drawl
• Charges for deviation receivable for over injection/ under
drawl by seller/buyer in excess of 12% of schedule or
150MW whichever is less shall be 0
• When schedule <= 400MW volume capping is fixed at
48MW
 When frequency is 50.10Hz and above
◦ Additional deviation charges payable for over injection/
under drawl in any time block when f>=50.10 Hz at Min of
ACP or 303.04 whichever is lower.
ERPC, KOLKATA 14

2. Under injection/Over drawl
• Charges for deviation payable for over drawl/ under
injection by buyer/seller within volume limit in a time
block in normal deviation charge depending on
frequency(Buyer)/Cap Rate(Seller).
• Additional deviation charges payable for over
drawl/under injection beyond the volume capping.
• When schedule <= 400MW volume capping is fixed at
48MW.
ERPC, KOLKATA 15

Additional Deviation Charge (Under injection/Over drawl)
1. When grid frequency is 49.85 Hz and above
• When 12% of schedule in a time block <= 150MW
• When 12% of schedule in a time block > 150MW
2. When grid frequency is below 49.85 Hz
ERPC, KOLKATA 16

Additional Deviation Charge (Over drawl)
ERPC, KOLKATA 17
When 12% <=150 MW When 12%> 150MW Additional Charges
12-15% 150-200MW 20 % of Normal
Deviation Charge
depending on average
freq of that block
15-20% 200-250MW 40 % of Normal
Deviation Charge
freq of that block
Above 20% Above 250 MW 100 % of Normal
Deviation Charge
freq of that block

Additional Deviation Charge (Under injection)
ERPC, KOLKATA 18
When 12% <=150 MW When 12%> 150MW Additional Charges
12-15% 150-200MW 20 % of MIN (Cape
rate, Deviation Charge
of that time block)
15-20% 200-250MW 40 % of MIN (Cape
of that time block)
Above 20% Above 250 MW 100 % of MIN (Cape
of that time block)

Additional Deviation Charge
2. When grid frequency is below 49.85 Hz
For Buyers
• Deviation Charge is payable at 800 p/u
• Additional Deviation Charge is levied at 800 p/u
For generators
• Deviation Charge is payable at 303.04 p/u
• Additional Deviation Charge is levied at 303.04 p/u.
ERPC, KOLKATA 19

1. Injection
• Domestic coal/lignite/hydro: Capped at 178 p/u
• Imported coal: Capped at 303 p/u
• RLNG: At 800 p/u
• Exemption from volume limit
• Exemption from sign change violation
2. Drawl
• Exemption from volume limit
• No additional charge
• Exemption from sign change violation
ERPC, KOLKATA 20

ERPC, KOLKATA 21
 A State whose minimum combined installed
capacity* of wind and solar power is 1000 MW or
more.
(* capacity installed as on the last day of the
previous month for present month.)

Deviation Charge for Wind/Solar:
ERPC, KOLKATA 22
Absolute Error (%) Under injection (Payable) Over injection (Receivable)
<=15% At the Fixed Rate up to 15% At the Fixed Rate up to 15%
>15% but <=25% At the fixed rate up to 15% +
110% of Fixed Rate for balance
energy >15% but <=25%
At the Fixed Rate up to 15% + 90%
of fixed rate for balance energy
>15% but <=25%
>25% but <=35% At the fixed rate up to 15% +
110% of fixed rate for balance
energy >15% but <=25% + 120%
of the Fixed Rate for balance
energy >25% but <=35%
At the fixed rate up to 15% + 90%
>15% but <=25% + 80% of the
Fixed Rate for balance energy
>25% but <=35%
>35% At the fixed rate up to 15% +
110% of fixed rate for balance
energy >15% but <=25% + 120%
energy >25% but <=35% + 130%
energy >35%
At the fixed rate up to 15% + 90%
>15% but <=25% + 80% of the
>25% but <=35% + 70% of the
>35%

ERPC, KOLKATA 23
For the period up to 31.03.2020 For the period from 01.04.2020
In the event of sustained deviation from
schedule continues for 12 time blocks, the
regional entity (buyer or seller), shall correct
its position by making the sign of its
deviation from schedule changed or by
remaining in the range of +/- 20 MW with
reference to its schedule, at least once,
latest by 13th time block. Addl. Charges of
10% of the time block DSM
payable/receivable shall be applicable in
case of said violation.
In the event of sustained deviation from
schedule continues for 6 time blocks, the
regional entity (buyer or seller), shall correct
its position by making the sign of its
deviation from schedule changed or by
remaining in the range of +/- 20 MW with
reference to its schedule, at least once,
latest by 7th time block. The additional
charge shall be at the rate as specified in the
following table.

1. Renewable energy generators which are regional entities
2. Run of river projects without pondage
3. Any infirm injection of power by a generating station prior to
CoD of a unit during testing and commissioning activities, in
accordance with the Connectivity Regulations.
4. Any drawl of power by a generating station for the start-up
activities of a unit.
5. Any inter-regional deviations.
6. Forced outage of a generating station in case of collective
transactions on Power Exchanges.
ERPC, KOLKATA 24

Buyers (Under drawl/Over drawl)
ERPC, KOLKATA 25
Sch
(MWH)
Act
(MWH)
Dev
(MWH)
Freq
(Hz)
New Dev
Rate if ACP
is 350 p/u
( Rs/MWH)
Volume
limit(Min of
12% of Sch
or 150 MW)
DC
Receivable
(+)/Payable(-)
(Rs.)
Quantum of
Deviation for
ADC(MWH)
ADC Payable
(Rs.)
1 -200 -250 -50 49.84 8000.0 24.00 -50*8000 0 -50*8000
2 -200 -280 -80 49.98 4062.5 24.00 -80*4062.5 56 -183625
3 -500 -600 -100 49.88 6875.0 37.50 -100*6875 62.5 -309375
4 -500 -600 -100 50.05 0.0 37.50 0 62.5 0
5 -200 -160 40 49.83 8000.0 24.00 24*8000 0 0
6 -200 -150 50 49.95 4906.3 24.00 24*4906.3 0 0
7 -200 -150 50 50.1 0.0 24.00 0 0 -50*3030.4
8 -90 -70 20 49.97 4343.8 12.00 12*6875 0 0
9 -50 -30 20 49.84 8000.0 12.00 12*8000 0 0
10 -30 -50 -20 49.83 8000.0 12.00 -20*8000 0
-20*8000

Sellers (Under injection/Over injection)
ERPC, KOLKATA 26
Sch
(MWH)
Act
(MWH)
Dev
(MWH)
Freq
(Hz)
New Dev
Rate if ACP
is 350 p/u
( Rs/MWH)
Dev Rate
Applicable
(Rs/MWH)
(Cap Rate)
Volume
limit(12%
of Sch or
150 MW)
DC
Receivable
(+)/Payable(-)
(Rs.)
Quantum
of Dev
for
ADC(MW
H)
ADC Payable
(Rs.)
1 1000 920 -80 49.84 8000 3030.4 37.50 -80*3030.4 0 -80*3030.4
2 1000 920 -80 49.95 4906.3 3030.4 37.5 -80*3030.4 42.5 -75760
3 1000 900 -100 50.11 0 0 37.5 0 62.5 0
4 1000 1100 100 49.90 6312.5 3030.4 37.5 37.5*3030.4 0 0
5 1000 1100 100 50.10 0 0 37.5 0 0 -100*3030.4
6 250 190 -60 50.02 2100 2100 30 -60*2100 30 -34650
7 250 300 50 50 3500 3030.4 30 30*3030.4 0 0
8 90 110 20 49.93 5468.8 3030.4 12 12*3030.4 0 0
9 90 110 20 50.05 0 0 12 0 0 0
10 100 80 -20 49.84 8000
3030.4
12 -20*3030.4 0 -20*3030.4

Infirm Power (Injection/ Drawl)
ERPC, KOLKATA 27
Sch
(MWH)
Act
(MWH)
Dev
(MWH)
Freq
(Hz)
Dev Rate
If ACPis
350P/U(
Rs/MWH)
Dev Rate
Applicable
(Rs/MWH)
(for APM)
DC
Receivable
(+)/Payable(-)
(Rs.)
Quantum of
deviation for
ADC(MWH)
ADC Payable
(Rs.)
1 0 10 10 49.95 4906.3 1780.00 10*1780 0 0
2
0 -10 -10 49.91 6031.3 6031.3
-10*6031.3
0 0
3 0 10 10 50.04 700 700 10*700 0 0
4 0 10 10 50.10 0 0 0 0 0
5
0 -10 -10 49.83 8000 8000 -10*8000 0 0

Solar (Over injection/ Under injection)
ERPC, KOLKATA 28
Sch
(MWH)
Act
(MWH)
Dev
(MWH)
Dev (MW) Absolute Error(%)
(ABS(Dev)/10))*100
Fixed Dev
Rate
( Rs/MWH)
DC
Receivable
(+)/Payable(-)
(Rs.)
1 2 1.99 -0.01 -0.04 0.4 9350 -0.01*9350
2 2 2.5 0.5 2 20 9350 4558.13
3 4 2.5 -1.5 6 60 9350 -16479.38

ERPC, KOLKATA 29
Schedule = -200 MWH Actual = -280 MWH Annex-I
Deviation = -280-(-200) = -80 MWH
Freq = 49.98 Hz, Dev Rate = 4062.5 Rs/MWH
Min ( 12% of sch=24, 37.5) = 24 MWH (So here 12% of sch <150MW or 37.5MWH)
DC payable=-80x4062.5=-325000
Over drawl allowed without levy of ADC= 24 MWH
Quantum of Over drawl on which ADC to be levied = 80-24 = 56 MWH
12-15% 15-20% Above 20%
3% of sch*20% of Dev
Rate of that time block=
0.03*200*0.2*4062.5= Rs
4875
0.05*200*0.4*4062.5= Rs
16250
(56-8% of sch)*100% of
Dev Rate of that time
block= (56-
16)*1*4062.5=Rs 162500
So total ADC= 4875+16250+162500=Rs 183625
DC & ADC Calculation for Buyer
Return

ERPC, KOLKATA 30
Schedule = -500 MWH Actual = -600 MWH Annex-II
Deviation = -600-(-500) = -100 MWH
Freq = 49.88 Hz, Dev Rate = 6875 Rs/MWH
Min ( 12% of sch=60, 37.5) = 37.5 MWH (So here 12% of sch>150MW or 37.5MWH)
DC payable=-100x6875=-687500
Over drawl allowed without levy of ADC= 37.5 MWH
Quantum of Over drawl on which ADC to be levied = 100-37.5 = 62.5 MWH
150-200 MW 200-250 MW Above 250 MW
(200-150)/4*20% of Dev
(200-150)/4*0.2*6875= Rs
17187.5
(250-200)/4*40% of Dev
(250-200)/4*0.4*6875= Rs
34375
(62.5-12.5-12.5)*100% of
block= 37.5*1*6875=Rs
257812.5
So total ADC= 17187.5+34375+257812.5=Rs 309375
DC & ADC Calculation for Buyer
Return

ERPC, KOLKATA 31
Schedule = 1000 MWH Actual = 920 MWH Annex-III
Deviation = 920-1000 = -80 MWH
Freq = 49.95 Hz, Dev Rate = 4906.3 Rs/MWH, Applicable rate=3030.4 Rs/MWH(Cap
Rate for Generators)
Min ( 12% of sch=120, 37.5) = 37.5 MWH (Here 12% of sch >150MW or 37.5MWH)
DC Payable=-100x3030.4 =-242432
Under injection allowed without levy of ADC= 37.5 MWH
Quantum of Under Injection on which ADC to be levied = 80-37.5 = 42.5 MWH
150-200 MW 200-250 MW Above 250 MW
(200-150)/4*20% of MIN
(303.04p/u, Deviation
Charge of that time
block)= 12.5*0.2*3030.4=
Rs 7576
(250-200)/4*40% MIN
(303.04p/u, Deviation
Charge of that time
block)= 12.5*0.4*3030.4=
Rs 15152
(42.5-12.5-12.5)*100%
MIN (303.04p/u,
Deviation Charge of that
time block)=
17.5*1*3030.4=Rs 53032
So total ADC= 7576+15152+53032=Rs 75760
DC & ADC Calculation for Generators
Return

ERPC, KOLKATA 32
Schedule = 250 MWH Actual = 190 MWH Annex-IV
Deviation = 190-250 = -60 MWH
Freq = 50.02 Hz, Dev Rate = 2100 Rs/MWH, Applicable rate=2100 Rs/MWH(Cap
Rate for Generators is 3030.4)
Min ( 12% of sch=30, 37.5) = 30 MWH (Here 12% of sch <150MW or 37.5MWH)
DC Payable=-60x2100 =-105000
Under injection allowed without levy of ADC= 30 MWH
Quantum of Under Injection on which ADC to be levied = 60-30 = 30 MWH
So total ADC= =3150+10500+21000=Rs 34650
12-15% 15-20% Above 20%
0.03*250*0.2*2100= Rs
3150
0.05*250*0.4*2100= Rs
10500
(30-8% of sch)*100% of
block= (30-20)*1*2100=Rs
21000
DC & ADC Calculation for Generators
Return

ERPC, KOLKATA 33
Schedule = 4 MWH Actual = 2.5 MWH Annex-V
Deviation = 2.5-4 = -1.5MWH or -6 MW
Fixed Dev Rate =9350 Rs/MWH
Absolute error (%) = ABS(-6MW/10MW)*100=60
Quantum of under injection at FR= 0.15*2.5=0.375 MWH
Quantum of under injection at 110% of the FR= 2.5*0.1 = 0.25 MWH
Quantum of under injection at 120% of the FR= 2.5*0.1 = 0.25 MWH
Quantum of under injection at 130% of the FR= 1.5-0.375-0.25-0.25 = 0.625 MWH
<=15% >15% but <=25% >25% but <=35% >35%
0.375*9350= Rs
3506.25
0.25*1.1*9350= Rs
2571.25
0.25*1.2*9350= Rs
2805
0.625*1.3*9350=
Rs 7596.875
So total DC= 3506.25+2571.25+2805+7596.875= Rs. 16479.38
Return

 All Regional entities including beneficiaries/Generators are responsible
for downloading SEM meter data and sending it to RLDC.
 RLDC further process the data and transmit the processed data to RPC
for accounting purpose.
 RLDC to also send the time block wise frequency for each day of the
week along with time block wise schedule for each Regional Entity for
each day of the week.
 RLDC to also intimate any discrepancy with respect to addition/outage
of any line in the network of any entity, outage of any generating unit,
any erroneous metering and any other information having commercial
implication.
 RLDC to furnish data by every Thursday.
ERPC, KOLKATA 34

 Design program as per relevant CERC regulation incorporating
various rate/volume capping/Cap rate and DSM rate vector for
accounting.
 Every week download the processed meter data along with Net
schedule, AGC schedule and frequency data sent by RLDC.
 ACP values for each day of the week is taken from NLDC website.
 Feed inputs(Actual, Net Schedule, AGC schedule, Frequency, ACP
values).
 RPC prepare and issue statement of deviation including
Additional charges for Deviation by every Tuesday for 7 day
period ending on Sunday.
 All payments including interest, if any, to be credited to “Regional
Deviation Pool Account Fund” operated by RLDCs.
ERPC, KOLKATA 35

 Payments to be made within 10 days issue of statement by RPC.
 For delay more than 2 days i.e. 12 days of issue of statement by RPC,
simple interest@0.04% to be levied for each of delay.
 If the delay of payment by payable entities, the receivable entities shall
be paid from the balance in the fund. If sufficient fund not there,
payment to be made on pro rata basis.
 Utilities defaulting at any time in previous FY shall open an LC equal to
110% of its average payable weekly liability in favour of concerned
RLDC.
 Utilities defaulting at any time in current FY shall open an LC equal to
110% of its weekly outstanding liability in favour of concerned RLDC.
 LC to increased to 110% of the payable weekly liability for Deviation in
any week during the year, if it exceeds the previous LC amount by more
than 50%.
 For payments not received within 12 days, RLDC entitled to encash the
LC to the extent of default which has been recouped within 3 days.
ERPC, KOLKATA 36

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