Modules · Compliance studies · Module 028
TPL-007-4 Geomagnetic Disturbance
Geomagnetic disturbance planned performance requirements for applicable transformers, documented and evidenced.
About this module
What this module covers.
This module develops your compliance procedure for NERC TPL-007-4, Transmission System Planned Performance for Geomagnetic Disturbance (GMD) Events, and applies it at each applicable plant. TPL-007-4 applies to Generator Owners whose Facilities include power transformer(s) with a high-side, wye-grounded winding and terminal voltage greater than 200 kV. It requires benchmark and supplemental thermal impact assessments of applicable BES power transformers based on GIC flow information provided by the PC and TP (benchmark at 75 A per phase or greater, supplemental at 85 A per phase or greater). This module covers development of the compliance procedure and GMD thermal impact assessments for each applicable plant.
Module: 028
Kind: Compliance studies
Governing body: NERC
Applies to: Operating plants
Typical time: About one week, all in
Dashboard capabilities
- Automated Compliance Workflow for TPL-007-4
- GIC / GMD thermal impact modeling support
Support services
What GridStrong does inside this module.
Task 1: Develop Compliance Procedure
- Create an audit-ready compliance procedure for meeting the TPL-007-4 requirements, working collaboratively across engineering and compliance departments. This includes:
- Identifying applicable assets, functions, SMEs, roles, responsibilities, and ownership
- Determining specific actions and evidence to demonstrate compliance with specific requirements and measures
- Conduct a gap analysis comparing current practices versus the standard requirements
- Develop clear step-by-step procedures for TPL-007-4 that align with internal controls and documentation policies, including receipt of GIC flow information from the PC/TP, thermal impact assessment, and transmittal of the assessment to the PC/TP
- Establish compliance timelines that align with standard implementation deadlines
- Define and determine specific compliance evidence per site
Task 2: Implementation of Compliance Procedure at each plant
- Gather all applicable documentation, models, data, etc. for each applicable plant, including GIC flow information from the PC and TP, transformer nameplate data, magnetic core designs, and any prior thermal impact assessments
- Conduct a thorough review of all existing plant data and documentation and compare against standard requirements and associated compliance procedures
- Perform benchmark and/or supplemental thermal impact assessments for applicable BES power transformers meeting the GIC thresholds
- Recommend changes needed to meet NERC TPL-007-4 requirements
- Identify and explain the compliance timelines needed to implement recommended changes
Final deliverables
- Compliance procedure for TPL-007-4.
- Benchmark and/or supplemental thermal impact assessment per applicable BES power transformer.
- Compliance report per applicable plant documenting methodology, findings, and recommendations.
What we need from you
- GIC flow information provided by the PC and TP for benchmark and supplemental events.
- Your transformer nameplate data, design information, and magnetic core characteristics for applicable BES power transformers.
- Any existing thermal impact assessments and PC/TP correspondence.
Assumptions and considerations
How the scope is bounded.
- Many IBR plants will not have transformers meeting the 200 kV high-side wye-grounded applicability criterion; in those cases the scope is limited to documenting non-applicability.
- You supply all required documentation and access to engineering SMEs.
- We will use engineering judgment and best practices to support compliance preparedness.
Other modules
Every module runs on the same record.
Run this module on one site.
Tell us the plant and the deadline. An engineer confirms the inputs, the schedule and what the Dashboard needs from you.