NERC Congestion Management

1. NERC Congestion Management  Congestion Management Option 3 Vendor Meeting Julie Pierce � NERC IDCWG Chair

2. 2 Objectives History of EI Congestion Management Overview of IDC functionality Overview of NERC TLR Procedure

3. 3 Congestion- What is it? A Few Power System Operator Answers: �Overloading the Transmission System� �Lines are on �Fire� �Too Much Generation for the Load� �Too Many MWs on the Lines for the given Topology�

4. 4 Congestion Management Basic Methods Available Re-Dispatch Moving generation to change the flow of energy on the transmission system Reconfiguration Changing the topology of the transmission system to create the desired system flow

5. 5 Transmission Flow - MWs Taking this simple case one step further, if we assume a generator output of 350 megawatts to serve a 400 megawatt load with a 50 MW import And the transmission corridor has 400 megawatts of transfer, and we will show that is due to other contracts flowing on the system.Taking this simple case one step further, if we assume a generator output of 350 megawatts to serve a 400 megawatt load with a 50 MW import And the transmission corridor has 400 megawatts of transfer, and we will show that is due to other contracts flowing on the system.

6. 6 History � NERC Congestion Mngt Prior to NERC Regional Congestion Management: Localized Congestion Management Procedures used to mitigate the overloading of lines Minimal number of operating agreements between NERC Reliability Regions No visibility of Parallel Flows caused by all the MW transactions and local load serving taking place on the Eastern Interconnect

7. 7 History � NERC Congestion Mngt Visibility of Parallel Flows was increased with implementation of Electronic Tagging of MW transfers from on balancing area to another. Implementation of E-tagging and NERC Policy 3 In conjunction with this effort was the NERC Regional Congestion Management proof of concept

8. 8 History � NERC Congestion Mngt Idea was that Congestion Management should be done on a larger regional basis due to the interconnection characteristics and parallel flows present on the system Assigning responsibility to those entities that were causing parallel flows was necessary to maintain reliability and equity during loading events

9. 9 History � NERC Congestion Mngt Transmission Loading Relief Procedure (TLR) NERC Policy 9 and associated Appendices Procedure defines several levels of transmission loading and mechanisms to remove MWs from the system. Goal is to maintain reliability while removing MWs from the system in an equitable manner

10. 10 History � NERC Congestion Mngt Transmission Loading Relief (TLR) Implemented in 1999 Interchange Distribution Calculator (IDC) created Adopted and used heavily by the majority of the Eastern Interconnect Created Visibility of Eastern Interconnect MW Impacts due to Industry day to day business Provided a useful analysis tool for Control Areas and Reliability Entities for Emergency and Non Emergency situations

11. 11 Interchange Distribution Calculator Basic Functionality Impact Calculation of MW Transfers Generation to Balancing Area Load Scheduled Transfers from one Balancing Area to another Define Responsibility For Loading events Who�s MWs are on the transmission line(s) of interest How Much Relief is Required? � Operator Input Prescription for achieving relief using TLR Process Rules

12. 12 Interchange Distribution Calculator Basic Functionality (Continued) Communications Transmit Responsibilities and Relief Prescriptions to affected parties Accept and display feedback Allow Visibility and Transparency into the impact of potential MW transfers and actual taking place

13. 13 IDC System Flow Diagram

14. 14 Transmission Loading Relief Summary of TLR Levels 1 - Warning 2 - Hold 3A - Reallocate Non-Firm 3B - Curtail Non-Firm/Halt Non-Firm Starting/Inc 4 - Reconfigure 5A - Reallocate Firm 5B - Curtail Firm 6 - Emergency 0 - TLR End

15. 15 Congestion Management and Option 3

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