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

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

3. “Too Many MWs on the Lines for the given Topology”
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. 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. Transmission Flow - MWs
Line Limit = 400 MW
Output = 350 MW
Load = 400 MW
Maximum Output = 500 MW
Generator A
Generator to Load MWs for BA(s)
(Not in MISO or PJM)
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.
Interchange Transactions
(E-Tags)
Market Flow for MISO and PJM
Parallel Flow Caused by the Tags and GN to Ld

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. 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. 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. 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. 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. 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. 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. IDC System Flow Diagram
Request for Relief
Flowgate Definition
Prescription for
relief
Model of System
IDC
Current Outages
Software
Users: Reliability
Market Flow
from MISO/PJM
Authorities and
Balancing Areas
ETAG Transactions

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. Congestion Management and Option 3
Calculating Impacts
Of Visible Transfers
Assigning Event Responsibility
Option 3:
Addresses New Method
To assign Responsibility
For loading events
Defining Appropriate Relief
Prescription
Option 3:
Addresses other
Alternatives to Reliably and
Economically get MWs off
The system.

16. Questions ?