Unscheduled Interchange charges and related

matters-CERC Regulations, 2009

With amendments

w.e.f. 53.5.2010

Definitions (1) In these regulations, unless the context otherwise requires,- (a) ‘Act’ means the Electricity Act, 2003 (36 of 2003); (b) ‘actual drawal’ in a time-block means electricity drawn by a

beneficiary or a buyer, as the case may be, measured by the interface meters; (c) ‘actual injection’ in a time-block means electricity generated or

supplied by the generating station or seller, as the case may be, measured by

the interface meters. (d) ‘beneficiary’ means the person purchasing electricity generated

from the generating station; (e) ‘buyer’ means a person, other than the beneficiary, buying

electricity through a transaction scheduled in accordance with the regulations of

the Commission applicable for short term open access, medium term

access and long term access;

(f) ‘generating station’ means a generating station whose tariff is determined by the Commission under clause (a) of sub-section (1) of Section 62 of the Act; (g) ‘Grid Code’ means the Grid Code specified by the Commission under clause (h) of sub-section (1) of Section 79 of the Act (h) 'Commission' means the Central Electricity Regulatory Commission referred to in sub-section (1) of section 76 of the Act; (i) ‘interface meters’ means interface meters as defined by the Central Electricity Authority under the Central Electricity Authority (Installation and Operation of Meters) Regulations, 2006, as amended from time to time; (j) ‘Load Despatch Centre’ means National Load Despatch Centre, Regional Load Despatch Centre or State Load Despatch Centre, as the case may be, responsible for coordinating scheduling of the generating station in accordance with the provisions of Grid Code

k) `scheduled generation’ at any time or for any period or time block means

schedule of generation in MW or MWh ex-bus given by the concerned Load Despatch Centre; (l) `scheduled drawal’ at any time or for any period or time block

means schedule of despatch in MW or MWh ex-bus given by the concerned

Load Despatch Centre;

(m) ‘seller’ means a person, other than a generating station supplying electricity through a transaction scheduled in accordance with the ( regulations specified by the Commission for short term open access,

medium term access and long term access; (n) ‘time-block’ means block of 15 minutes, for which specified

electrical parameters and quantities are recorded by special energy meter, with

first time block starting at 00.00 Hrs;

(o) ‘Unscheduled Interchange’ in a time-block for a generating station or a

seller means its total actual generation minus its total scheduled generation and for a beneficiary or buyer means its total actual drawal minus its total scheduled drawal. (2) Save as aforesaid and unless repugnant to the context or the

subjectmatter otherwise requires, words and expressions used in these regulations and not defined, but defined in the Act, or the Grid Code or the Central

Electricity Regulatory Commission (Terms and conditions of Tariff) Regulations, 2009 shall have the meanings assigned to them respectively in the Act or the

Grid Code or the Central Electricity Regulatory Commission (Terms and

conditions of Tariff) Regulations, 2009.

Objective

The objective of these regulations is to maintain grid discipline as envisaged under the

Grid Code through the commercial mechanism of Unscheduled Interchange Charges by

controlling the users of the grid in scheduling, dispatch and drawl of electricity.

Scope

These regulations shall be applicable to – (i) the generating stations and the

beneficiaries, and (ii) sellers and buyers involved in the

transaction facilitated through open access or

medium term access or long-term access in inter-State transmission

Limits on UI volume and consequences of crossing limits

(1) The over-drawal of electricity from the schedule by any beneficiary or a buyer

during a time-block shall not exceed 12% of its scheduled drawal or 150 MW

(whichever is lower) when frequency is below 49.7 Hz, and 3% on a daily

aggregate basis for all time blocks when the freq is below 49.7Hz.

(2) The under-injection of electricity from the schedule by a generating station or by

a seller during a time-block shall not exceed 12% of the scheduled injection of

such generating station or seller when frequency is below 49.7 Hz, and 3% on

daily aggregate basis for all time blocks when the freq is below 49.7Hz.

. (3) In addition to UI Rate corresponding to frequency of

49.5 Hz, as stipulated under regulation 5, an Additional Unscheduled

Interchange Charge at the rate equivalent to 40% of the UI Rate corresponding to

frequency of 49.5 Hz shall be applicable for over-drawal or under-injection of electricity

for each time-block when grid frequency is below 49.5 Hz.

Provided that for under-injection of electricity during the time-block when grid frequency is below 49.5 Hz to 49.2Hz for the generating stations using coal

or lignite or gas supplied under Administered Price Mechanism (APM) as the fuel, Additional Unscheduled Interchange Charge shall be equivalent to 20% of the UI Cap Rate and for below 49.2Hz it is 40% of the cap rate.

Note: The Additional Unscheduled Interchange Charge shall be reviewed by the Commission on six-monthly basis or earlier, and revised, if necessary through separate orders. (4) Payment of Unscheduled Interchange Charges under regulation 5 and the Additional Unscheduled Interchange Charge under Regulation 7(3) above, shall be without prejudice to any action that may be considered appropriate under section 142 and section 149 of the Act for contravention of the over-drawal and under-generation limit specified in these regulations, for a time block when frequency is below 49.5 Hz. (5) The Commission may from time to time, if considered necessary, prescribe

the Additional Unscheduled Interchange Charge for over-drawal or under-injection of electricity during the time-block when grid frequency is below 49.5 Hz and up to 49.2 Hz.

Compliance with instructions of Load Despatch Centre

Notwithstanding anything specified in Regulations 6 and 7, the generating station, the

seller, the beneficiary and the buyer shall follow the instructions of the Regional Load

Despatch Centre on generation and drawal.

. Unscheduled Interchange Charges Accounting

All payments on account of Unscheduled Interchange charges including the Additional

Unscheduled Interchange Charges levied under these regulations and interest received

on late payment thereof shall be credited to a Fund called the “Unscheduled

Interchange Pool Account Fund”, which shall be maintained and operated in

accordance with provisions of the Grid Code.

. Schedule of Payment of Unscheduled Interchange

Charges (1) All payments for Unscheduled Interchange charges including the Additional Unscheduled Interchange Charge shall be made to the “Unscheduled Interchange

Pool Account Fund” within 10 days of issue of Unscheduled Interchange account

statement by the Regional Power Committee. (2) If any payments for the Unscheduled Interchange charges on the Additional Unscheduled Interchange Charge are delayed by more than two days, that is to say, payments are made beyond a period of 12 days of issue of the statement by the Regional Power Committee, simple interest @0.04% for each day of delay shall be payable. (3) All payments from the Unscheduled Interchange Pool Account Fund to the entities entitled to receive any amount shall be made within 5 days of crediting of the

amount to “Unscheduled Interchange Pool Account Fund”.

UI rate @50Hz= 155ps/uMedian of of Average cost of Coal/

Lignite for 08/09-01/10 UI rate @49.7Hz= 403ps/u

sufficient incentive to the generating station based on coal including imported coal

UI rate @49.5Hz= 873 ps/uhighest of the average energy charges

of generating stations for 08/09-01/10

UI computations

UI vector w.e.f 03-05-10

0

100

200

300

400

500

600

700

800

900

1000

49.34

49.38

49.42

49.46 49

.549

.5449

.5849

.6249

.66 49.7

49.74

49.78

49.82

49.86 49

.949

.9449

.9850

.0250

.06 50.1

50.14

50.18

50.22

50.26 50

.3Frequency in Hz.

UI

rate

in

Ps

/u

49.7Hz 403ps/u

49.5Hz 873ps/u

50.2Hz 0 ps/u

50.0Hz 155 ps/u

Generators under APM fuel: If the UI rate in a time block exceeds 403 ps/u

then the UI rate for the station is restricted to = 403ps/u

Restricted cap rates For over-generation in a time block beyond

105% of the Declared Capacity i.e. if the generation is 105% to 107% (say) then for the extra 2% beyond 105% the rate = 155ps/u

For over-generation when the generation exceeds 101% of the Declared Capacity over an entire day then for any time block in that day,when the generation is say 104% then for the extra 3% (104%-101%) the rate is = 155ps/u

Beneficiary or Buyer : For Underdrawal upto10% or 250MW

whichever is less = No cap For Underdrawal beyond 10% or 250MW shall

not exceed 403ps/u For Eg:- if AP has schedule of 100 MW,but is

underdrawing at 91MW then for the 9MW the prevailing rate applies. But, if it is underdrawing at 88MW and if the rate is 873ps/u (i.e. more than 403ps/u) then for 2MW (i.e. 100-10% of 100=90;90-88=2) the rate will be restricted to 403ps/u

For Sellers For Overgeneration upto 120% of

Schedule = No cap For Overgeneration beyond 120% of

Schedule but upto 105% of Installed capacity =403ps/u

Restricted Cap Rates For Overgeneration beyond 105% of IC in

a block or 101% of IC in a day = 155ps/u

Additional UI is independent of individual behaviour of any constituents/ISGS/Seller

It is dependent solely on frequency. Two frequency slabs1. 49.5 Hz < SR/ER frequency < 49.2 Hz2. SR/ER frequency < 49.2 Hz

For Beneficiary/Seller If Overdrawing then

40 % of rate at 49.5 Hz i.e. 40% of 873ps/u If Underinjecting then

20% of rate at 49.5 Hz i.e. 20% of 873ps/u For ISGS

Only for underinjecting20% of rate at 49.7 Hz i.e. 20% of 403ps/u

For Beneficiary/Seller If Overdrawing then

100 % of rate at 49.5 Hz i.e. 873ps/u If Underinjecting then

40% of rate at 49.5 Hz i.e. 40% of 873ps/u For ISGS

Only for underinjecting40% of rate at 49.7 Hz i.e. 40% of 403ps/u

UI = Schedule – Actual Taken from .tn1/kp1/… & .re1 files Nuclear UI Adjustment to be taken into

picture.

Case study: Suppose KAPS has a Schedule of 100MW.As per

schedule its allocation has been split equally between KA,KL,TN,AP.

Now,let its Actual be 104MW. So, KA gets 26MW=KL=TN=AP. Each state gets an extra of 1MW. If there was no nuclear UI, then let UI of each state

be 100,200,300,400 MW respectively Now, when there is nuclear UI,then the UI of each

state is adjusted by 1MW. Resultant UI becomes 99,199,299,399MW for

respective beneficiaries.

After the nuclear adjustment is done (for all 4 nuclear PPs) this resultant/effective/total UI is from now on taken as the normal UI.

So amount for the UI (Rs) = 2.5 * UI (in MW) * rate (in ps/KWh) for that particular time block

Calculation of quantity of UI to be restricted = X (say…)

Restricted amount = 2.5*restricted rate * X

Restricted rate = 155ps/u iff prevailing rates more than 155ps/u

Valid only for ISGS & Seller

For ISGS/Seller –> Quantity of UI to be capped = UI – X

Capped amount = 2.5*(UI - X)*capped rate(403ps/u)

For beneficiary,Capped amount = 2.5*quantity*capped rate(403ps/u)

Quantity = beyond 10% of Schedule or 250MW,whichever is less.

For seller Rate = 403ps/u when UI > 120% of

schedule but when UI < 105% of IC. Capped amount = 2.5*UI*rate. Quantity = UI

Applicable only when frequency is lower than identified frequencies i.e., < 49.5 Hz and < 49.2 Hz .

Amount = 2.5*rate*UI Rate is dependent on frequency, type of

constituents and overdrawal/underinjection.