IRO-006-EAST-1: TLR Procedure for the Eastern Interconnection

Purpose
To provide an Interconnection-wide transmission loading relief procedure (TLR) for the Eastern Interconnection that can be used to prevent and/or mitigate potential or actual System Operating Limit (SOL) and Interconnection Reliability Operating Limit (IROL) exceedances to maintain reliability of the Bulk Electric System (BES).

Applicability

Reliability Coordinators in the Eastern Interconnection

Proposed Effective Date
First day of the first calendar quarter following the date this standard is approved by applicable regulatory authorities, or in those jurisdictions where regulatory approval is not required, the standard becomes effective on the first day of the first calendar quarter after the date this standard is approved by the NERC Board of Trustees.

Requirements
R1. When acting or instructing others to act to mitigate the magnitude and duration of the instance of exceeding an IROL within that IROL’s TV, each Reliability Coordinator shall initiate, prior to or concurrently with the initiation of the Eastern Interconnection TLR procedure (or continuing management of this procedure if already initiated), one or more of the following actions: [Violation Risk Factor: High] [ Time Horizon: Real-time Operations]

• Inter-area redispatch of generation
• Intra-area redispatch of generation
• Reconfiguration of the transmission system
• Voluntary load reductions (e.g., Demand-side Management)
• Controlled load reductions (e.g., load shedding)

R2. To ensure operating entities are provided with information needed to maintain an awareness of changes to the Transmission System, when initiating the Eastern Interconnection TLR procedure to prevent or mitigate an SOL or IROL exceedance, and at least every clock hour (with the exception of TLR-1, where an hourly update is not required) after initiation up to and including the hour when the TLR level has been identified as TLR Level 0, the Reliability Coordinator shall identify: [Violation Risk Factor: Medium] [ Time Horizon: Real-time Operations]

2.1. A list of congestion management actions to be implemented, and

2.2. One of the following TLR levels: TLR-1, TLR-2, TLR-3A, TLR-3B, TLR-4, TLR-5A, TLR-5B, TLR-6, TLR-0 ¹

R3. Upon the identification of the TLR level and a list of congestion management actions to be implemented, the Reliability Coordinator initiating this TLR procedure shall: [Violation Risk Factor: Medium] [Time Horizon: Real-time Operations]

3.1. Notify all Reliability Coordinators in the Eastern Interconnection of the identified TLR level

3.2. Communicate the list of congestion management actions to be implemented to 1.) all Reliability Coordinators in the Eastern Interconnection, and 2.) those Reliability Coordinators in other Interconnections responsible for curtailing Interchange Transactions crossing Interconnection boundaries identified in the list of congestion management actions.

3.3. Request that the congestion management actions identified in Requirement R2, Part 2.1 be implemented by:

1. Each Reliability Coordinator associated with a Sink Balancing Authority for which Interchange Transactions are to be curtailed,
2. Each Reliability Coordinator associated with a Balancing Authority in the Eastern Interconnection for which Network Integration Transmission Service or Native Load is to be curtailed, and
3. Each Reliability Coordinator associated with a Balancing Authority in the Eastern Interconnection for which its Market Flow is to be curtailed.

R4. Each Reliability Coordinator that receives a request as described in Requirement R3, Part 3.3. shall, within 15 minutes of receiving the request, implement the congestion management actions requested by the issuing Reliability Coordinator as follows: [Violation Risk Factor: High] [ Time Horizon: Real-time Operations]

• Instruct its Balancing Authorities to implement the Interchange Transaction schedule change requests.
• Instruct its Balancing Authorities to implement the Network Integration Transmission Service and Native Load schedule changes for which the Balancing Authorities are responsible.
• Instruct its Balancing Authorities to implement the Market Flow schedule changes for which the Balancing Authorities are responsible.
• If an assessment determines shows that one or more of the congestion management actions communicated in Requirement R3, Part 3.3 will result in a reliability concern or will be ineffective, the Reliability Coordinator may replace those specific actions with alternate congestion management actions, provided that:
  • The alternate congestion management actions have been agreed to by the initiating Reliability Coordinator, and
  • The assessment shows that the alternate congestion management actions will not adversely affect reliability.

Measures
M1. Each Reliability Coordinator shall provide evidence (such as dated logs, voice recordings, or other information in electronic or hard-copy format) that when acting or instructing others to act to mitigate the magnitude and duration of the instance of exceeding an IROL within that IROL’s Tv, the Reliability Coordinator initiated one or more of the actions listed in R1 prior to or concurrently with the initiation of the Eastern Interconnection TLR procedure (or continuing management of this procedure if already initiated)(R1).

M2. Each Reliability Coordinator shall provide evidence (such as dated logs, voice recordings, or other information in electronic or hard-copy format) that at the time it initiated the Eastern Interconnection TLR procedure, and at least every clock hour after initiation up to and including the hour when the TLR level was identified as TLR Level 0, the Reliability Coordinator identified both the TLR Level and a list of congestion management actions to be implemented (R2).

M3. Each Reliability Coordinator shall provide evidence (such as dated logs, voice recordings, or other information in electronic or hard-copy format) that after it identified a TLR level and a list of congestion management actions to take, it

1. notified all Reliability Coordinators in the Eastern Interconnection of the TLR Level,
2. communicated the list of actions to all Reliability Coordinators in the Eastern Interconnection and those Reliability Coordinators in other Interconnections responsible for curtailing Interchange Transactions crossing Interconnection boundaries identified in the list of congestion management actions, and
3. requested the Reliability Coordinators identified in Requirement R3 Part 3.2 to implement the congestion management actions identified in Requirement R2 Part 2.1 (R3).

M4. Each Reliability Coordinator shall provide evidence (such as dated logs, voice recordings, or other information in electronic or hard-copy format) that within fifteen minutes of the receipt of a request as described in R3, the Reliability Coordinator complied with the request by either

1.  implementing the communicated congestion management actions requested by the issuing Reliability Coordinator, or
2.  implementing none or some of the communicated congestion management actions requested by the issuing Reliability Coordinator, and replacing the remainder with alternate congestion management actions if assessment showed that some or all of the congestion management actions communicated in R3 would have resulted in a reliability concern or would have been ineffective, the alternate congestion management actions were agreed to by the initiating Reliability Coordinator, and assessment showed that the alternate congestion management actions would not adversely affect reliability (R4).

Associated Documents

Implementation Guideline for Reliability Coordinators:
Eastern Interconnection TLR Levels Reference Document