APPENDIX D
IMBALANCE ENERGY CHARGE COMPUTATION
D 1	Purpose of charge
The Imbalance Energy charge is the term used for allocating the cost of not only the Imbalance Energy (the differences between scheduled and actual Generation and Demand), but also any Unaccounted for Energy (UFE) and any errors in the forecasted Transmission Losses as represented by the GMMs.  Any corresponding cost of Dispatched Replacement Reserve Capacity that is not allocated as an Ancillary Service is also included along with the Imbalance Energy charge.
D 2	Fundamental formulae
D 2.1	Imbalance Energy Charges on Scheduling Coordinators
Uninstructed Imbalance Energy attributable to each Scheduling Coordinator in each Settlement Period in the relevant Zone shall be deemed to be sold or purchased, as the case may be, by the ISO and payments for Uninstructed Imbalance Energy shall be settled by debting or crediting, as the case may be, the Scheduling Coordinator with an amount for each Settlement Period equal to the sum of:
(a)	The quantity of undelivered Instructed Imbalance Energy, multiplied by the Effective Price, and
(b)	The quantity of deviation from the final Hour-Ahead Schedule multiplied by the Hourly Ex Post Price.
Imbalance Energy charge will be calculated as follows:
IECharge=DevC + ASSEDevC
Where:

and
The deviation between scheduled and actual Energy Generation for Generator i represented by Scheduling Coordinator j in Zone x during Trading Interval t is calculated as follows:
GenDevi = Gs * GMMf –[(Ga - Gadj) * GMMah – Ga/s  – Gs/e]- UnavailAncServMWixt
Where:
UnavailAncServMWixt =	Max[ – (Gi, oblig – Ga/s) Min(0,Pmaxi-Ga-(Gi, oblig - Ga/s)]
GenDevCi=GenDevi*P in case of (b) above, and 
If Ga/s +Gs/e > 0 and P < Peff then:
ASSEGenDevCi=Max[0,[Ga/s-Max[0,(Ga-Gadj-Gs)]]]*(Peff-l - P) in case of (a) above, or 
If Ga/s +Gs/e< 0 and P > Peff then:
ASSEGenDevCi=Min[0,[Ga/s-Min[0,(Ga-Gadj-Gs)]]]*(Peff-l -P) in case of (a) above,

The deviation between scheduled and actual Load consumption for Load i represented by Scheduling Coordinator j in Zone x during Trading Interval t is calculated as follows:
- UnavailDispLoadMWixt
Where:
UnavailDispLoadMWixt	=	Max[0, (Li, oblig – La/s) –La]
LoadDevCi=LoadDevi * P in case of (b) above, and 
If La/s +Ls/e > 0 and P < Peff then:
ASSELoadDevCi=Max[0,[La/s-Max[0,(La/s-Ladj-Ls)]]]*(Peff-l -P) in case of (a) above, or
If La/s + Ls/e < 0 and P > Peff then:
ASSELoadDevCi=Min[0,[La/s-Min[0,(La/s-Ladj-Ls)]]]*(Peff-l -P) in case of (a) above
The deviation between forward scheduled and Real Time adjustments to Energy imports*, adjusted for losses, for Scheduling Point q represented by Scheduling Coordinator j into Zone x during Trading Interval t is calculated as follows:
ImpDevq = Is * GMMfq – [(Ia – Iadj) *GMMahq]+Ia/s
ImpDevCi=ImpDevi * P in case of (b) above, and 
If la/s > 0 and P < Peff then:
ASSEImpDevCi=Max[0,[la/s-Max[0, (la-ladj-ls)]]]*(Peff-q - P) in case of (a) above, or
If la/s < 0 and P > Peff then:
ASSElmpDevCi=Min[0,[la/s-Min[0, (la-ladj-ls)]]]* (P eff-q - P) in case of (a) above
The deviation between forward scheduled and Real Time adjustments to Energy exports* for Scheduling Point q represented by Scheduling Coordinator j from Zone x during Trading Interval t is calculated as follows:

ExpDevCq=ExpDevq * P
D 2.2	Unaccounted for Energy Charge
The hourly Unaccounted for Energy Charge on Scheduling Coordinator j for Trading Interval t for each relevant Zone is calculated in the following manner:
The UFE for each utility service territory k is calculated as follows,

The Transmission Loss calculation per Trading Interval t per relevant Zone for each utility service territory k is calculated as follows,

Each metered demand point, either ISO grid connected or connected through a UDC, is allocated a portion of the UFE as follows:

The UFE charge for Scheduling Coordinator j per Trading Interval per relevant Zone is then,

		D 3	Meaning of terms of formulae
D 3.1	IECj – $
The Imbalance Energy charge on Scheduling Coordinator j in Trading Interval t for each relevant Zone.
D 3.2	GenDevi – MWh
The deviation between scheduled and actual Energy Generation for Generator i represented by Scheduling Coordinator j in Zone x during Trading Interval t.
D 3.3	LoadDevi – MWh
The deviation between scheduled and actual Load consumption for Generator i represented by Scheduling Coordinator j in Zone x during Trading Interval t.
D 3.4	ImpDevq – MWh
The deviation between forward scheduled and Real Time adjustments to Energy imports, as adjusted for losses, for Scheduling Point q represented by Scheduling Coordinator j into Zone x during Trading Interval t.
D 3.5	ExpDevq – MWh
The deviation between forward scheduled and Real Time adjustments to Energy exports for Scheduling Point q represented by Scheduling Coordinator j 
from Zone x during Trading Interval t.
D 3.6	Gs – MWh
The total scheduled Generation of Scheduling Coordinator j for Generator i in Trading Interval t as a result of both the Day-Ahead Final Schedule and the Hour-Ahead Final Schedule.
D 3.7	Ga – MWh
The total actual metered Generation of Scheduling Coordinator j for Generator i in Trading Interval t.
D 3.8	Gadj – MWh
Deviations in real time ordered by the ISO for purposes such as Congestion Management.
D 3.9	Ga/s – MWh
The Energy generated from Ancillary Service resource i due to ISO dispatch instructions.  This value will be calculated based on the projected impact of the Ancillary Services dispatch instruction(s) over the time period within the Trading Interval for which such Ancillary Services dispatch instruction(s) applies.
D.3.9.1	Gs/e -MWh
The Energy generated from Supplemental Energy resource i due to ISO dispatch instructions.  This value will be calculated based on the projected impact of the Supplemental Energy dispatch instruction(s) over the time period within the Trading Interval for which such Supplemental Energy dispatch instruction(s) applies.
D 3.10	GMMf – fraction
The forecasted Generation Meter Multiplier (GMM) for Generator i as provided to the Scheduling Coordinator by the ISO in advance of the operation of the Day-Ahead Market.
D 3.11	GMMfq – fraction
The forecasted Generation Meter Multiplier for an Energy import at Scheduling Point q as provided to the Scheduling Coordinator by the ISO in advance of the Day-Ahead Market.
D 3.12	GMMah – fraction
The final forecasted Generation Meter Multiplier (GMM) for a Generator i as calculated by the ISO at the hour-ahead stage (but after close of the Hour-Ahead Market).
D 3.13		GMMahq – fraction
The forecasted Generation Meter Multiplier for an Energy import at Scheduling Point q as provided to the Scheduling Coordinator by the ISO after close of the Hour-Ahead Market.
D 3.14	Ls – MWh
The total scheduled Demand of Scheduling Coordinator j for Demand i in Trading Interval t as a result of both the Day-Ahead Final Schedule and the Hour-Ahead Final Schedule.
D 3.15	La – MWh
The total actual metered Demand of Scheduling Coordinator j for Demand i in Trading Interval t.
D 3.16	Ladj – MWh
The deviation in realtime Demand (i.e., Load bidding into the market) ordered by the ISO for Congestion Management, Overgeneration, etc.].  This value will be calculated based on the projected impact of the Dispatch instruction(s) over the time period within the Trading Interval for which such Dispatch instruction(s) applies.
D 3.17	La/s – MWh
The Energy reduction by curtailable Load due to ISO dispatch of Ancillary Services from such curtailable Load (i.e., Load bidding into the Ancillary Services markets).  This value will be calculated based on the projected impact of the Ancillary Services dispatch instruction(s) over the time period within the Trading Interval for which such Ancillary Services dispatch instruction(s) applies.
D 3.17.1	Ls/e -MWh
The Energy reduction by curtailable Load due to ISO dispatch of Supplemental Energy from such curtailable Load.  This value will be calculated based on the projected impact of the Supplemental Energy dispatch instruction(s) over the time period within the Trading Interval for which such Supplemental Energy dispatch instruction(s) applies.
D 3.18	Is – MWh
The total scheduled Energy import of Scheduling Coordinator j through Scheduling Point q in Trading Interval t as a result of both the Day-Ahead Final Schedule and the Hour-Ahead Final Schedule.
D 3.19	Ia – MWh
The total actual Energy import of Scheduling Coordinator j through Scheduling Point q in Trading Interval t.  This is deemed to be equal to the total scheduled Energy import Is.
D 3.20	Iadj – MWh
The deviation in real time import ordered by the ISO for congestion management, overgeneration, etc. or a result of an import curtailment.  This value will be calculated based on the projected impact of the Dispatch instruction(s) (or curtailment event) between the close of the Hour-Ahead Market and the end of the Trading Interval for which such Dispatch Instructions(s) (or curtailment event) applies.
D 3.21	Ia/s – MWh
The Energy generated from Ancillary Service System Resources pursuant to Existing Contracts or Supplemental Energy from interties due to ISO’s Dispatch instruction.
D 3.22	Es – MWh
The total scheduled Energy export of Scheduling Coordinator j through Scheduling Point q in Trading Interval t as a result of both the Day-Ahead Final Schedule and the Hour-Ahead Final Schedule.
D 3.23	Ea – MWh
The total actual Energy export of Scheduling Coordinator j through Scheduling Point q in Trading Interval t.  This is deemed to be equal to the total scheduled Energy export Es.
D 3.24	Eadj – MWh
The deviation in Real Time export ordered by the ISO for Congestion Management, Overgeneration, etc. or as a result of an export curtailment.  This value will be calculated based on the projected impact of the Dispatch Instruction(s) (or curtailment event between the close of the Hour-Ahead Market and the end of the Trading Interval for which such Dispatch Instruction (or curtailment event) applies.
D 3.25	Pxt – $/MWh
The Hourly Ex Post Price for Imbalance Energy for the relevant Trading Interval.  This value is calculated as the weighted average of the 12 Five Minute Ex Post Prices in each Zone during each hour.  The Five Minute Ex Post Price is equal to the bid price of the marginal resource accepted by the ISO for dispatch and deemed eligible to set the price during a five minute period.
D 3.25.1	Peff – $
Effective Price for Instructed Imbalance Energy for the relevant Settlement Period.
D 3.26	UFECj – $
The Unaccounted for Energy Charge for Scheduling Coordinator j is the cost representing the difference in Energy, for each UDC Service Area and Trading Interval, between the net Energy delivered into the UDC Service Area, adjusted for UDC Service Area Transmission Losses (calculated in accordance with ISO Tariff Section 7.4.3), and the total metered Demand within the UDC Service Area adjusted for distribution losses using Distribution System loss factors approved by the Local Regulatory Authority.
This difference (UFE) which is attributable to meter measurement errors, power flow modeling errors, energy theft, statistical Load profile errors, and distribution loss deviations is multiplied by the Hourly Ex-Post Price.