External Interface Congestion Price Assignment. The RTC optimization will determine the External Interface Congestion at an External Proxy Bus for a CTS Enabled Interface if the net interchange schedule is limited in the RTC solution due to one or more of the following four reasons: (i) there are more economic transactions offered in a common direction (import or export) than the Transfer Limit of the External Proxy Bus can accommodate, or (ii) there are fewer economic transactions offered in a common direction (import or export) than the Transfer Limit requires, or (iii) the NYCA (system-wide) Ramp Limit prevents the RTC from scheduling one or more external transactions at the External Proxy Bus consistent with the economics of the underlying bids, or (iv) a Ramp Limit prevents the RTC from scheduling one or more external transactions consistent with the economics of the underlying bids (collectively, the “External Proxy Bus Constraints”). Whenever an External Proxy Bus Constraint at a CTS Enabled Interface is limiting in the RTC optimization, the External Interface Congestion at the External Proxy Bus will be assigned, in whole or in part, as set forth below. ISO-NE Limiting: If the RTC optimization is limited by a Transfer Limit determined by an ISO-NE Operating Reserve limitation, an ISO-NE minimum generation limitation, or an ISO-NE capacity deliverability limit, including when the Transfer Limit is adjusted in accordance with Section 5.4 of this Schedule D to accommodate the Ramp Limit while implementing one of these limitations, then the portion of the External Interface Congestion associated with the External Proxy Bus Constraint shall be assigned to ISO-NE. NYISO Limiting: If the RTC optimization is limited by NYCA-wide Ramp Limits, then the portion of the External Interface Congestion associated with the External Proxy Bus Constraint shall be assigned to NYISO. NYISO and ISO-NE Limiting: If the RTC optimization is limited by any Ramp Limit or Transfer Limit that is not specifically addressed in the “ISO-NE Limiting” or “NYISO Limiting” paragraphs above, or by any Transfer Limit or Ramp Limit that results from an operator override, as described in Section 5.2.5 of this Schedule D, the portion of the External Interface Congestion for a CTS Enabled Interface that is associated with an External Proxy Bus Constraint shall be assigned to both Parties equally. The RTC solution may be limited by multiple External Proxy Bus Constraints simultaneously. If this occurs, the foregoing rules will apply to e...
External Interface Congestion Price Assignment. The RTC optimization will determine the External Interface Congestion at an External Proxy Bus for a CTS Enabled Interface if the net interchange schedule is limited in the RTC solution due to one or more of the following four reasons: (i) there are more economic transactions offered in a common direction (import or export) than the Transfer Limit of the External Proxy Bus can accommodate, or (ii) there are fewer economic transactions offered in a common direction (import or export) than the Transfer Limit requires, or (iii) the NYCA (system-wide) Ramp Limit prevents the RTC from scheduling one or more external transactions at the External Proxy Bus consistent with the economics of the underlying bids, or (iv) a Ramp Limit prevents the RTC from scheduling one or more external transactions consistent with the economics of the underlying bids (collectively, the “External Proxy Bus Constraints”). Whenever an External Proxy Bus Constraint at a CTS Enabled Interface is limiting in the RTC optimization, the External Interface Congestion at the External Proxy Bus will be assigned, in whole or in part, as set forth below.
External Interface Congestion Price Assignment. Under the current inter-regional trading system, ISO-NE and NYISO do not exchange the information necessary to calculate an economically correct congestion price associated with a binding external interface limit.21 Under Coordinated Transaction Scheduling, each ISO will set a congestion component for the CTS Enabled Interface LMP when there is a binding external interface limit. When the external interface is binding at the time it is scheduled, the difference between one ISO’s incremental cost of sending power and the other ISO’s decremental cost of receiving power comprises the total congestion price across the interface. The ISOs will incorporate this difference, less the net amount paid to the marginal (i.e., last accepted) CTS Interface Bid, into the congestion component of their real-time LMPs associated with the CTS Enabled Interface.22 As ISO-NE explained in the ISO-NE CTS Filing, to avoid both ISO-NE and the NYISO charging the total congestion price to market participants (which would result in the double-counting of congestion charges), the total of the two regions’ congestion components of the real-time LMPs associated with an external interface will add up to the desired total congestion price determined at the time the interface is scheduled.23 Section 4.2 of Schedule D addresses how congestion will be allocated between the two regions, with the allocation being based on the cause of the congestion. As described in Section 5.2 of Schedule D, transfer limits will be submitted by ISO-NE to NYISO to help ensure that the economic objective of the RTC solution for clearing CTS Interface Bids does not create or worsen a reliability condition in ISO-NE. When congestion is caused by any of these transfer limits, the congestion will be allocated to ISO-NE and incorporated into the ISO-NE LMP at the External Proxy Bus associated with the CTS Enabled Interface. When the congestion is caused by a NYISO ramping limit, then the congestion will be 21 Congestion is a condition in which transmission system operating limits prevent unconstrained economic dispatch of the power system. Congestion is captured in the Congestion Component of the LMP. The Congestion Component of the LMP differs across locations within the New England transmission system whenever one (or more) internal transmission limits are binding.
