Modules · Modeling studies · Module 046
Southern Company Model Quality Assessment
Model quality assessment support for inverter-based resource model development and compliance in Southern Company's territory.
About this module
What this module covers.
Southern Company released its Model Submittal Requirements for Transmission Connected Inverter-Based Resources (the applicable requirements), effective April 18, 2025, which define the modeling requirements and the Model Quality Assessment (MQA) that must be conducted for newly interconnecting inverter-based resource (IBR) projects. We support IBR model development across simulation platforms and generate the materials that meet Southern Company's requirements.
This module digitizes the collection, review, and delivery of the final modeling package and supplemental information. Our subject matter experts develop the models and conduct the MQA in compliance with Southern Company's requirements.
At a glance
Module: 046
Kind: Modeling studies
Governing body: Southern Company
Applies to: Before and after commercial operation
Typical time: Two to three weeks, all in, including your review
Dashboard capabilities
- Southern Company MQA report generation
- Model Workspace Management: your plant's simulation model files kept in one dashboard workspace, with version tracking
Support services
What GridStrong does inside this module.
Task 1: PSS/E Standard Library Model and User-Defined Model (UDM) Development
- Coordinate with you and the applicable original equipment manufacturer(s) (OEMs) to gather and review all supplied site-specific models.
- Clarify to the OEM what information will be required to meet Section 3 and Section 4 of the applicable requirements.
- Develop plant-level aggregated PSS/E standard library model that meets applicable requirements.
- Develop plant-level aggregated PSS/E user-defined model that meets applicable requirements.
- Configure the PSS/E models with controls, settings, and tuning specific for the proposed project to meet the performance requirements specified.
- Perform PSS/E model performance tests as outlined in Section 4 of the applicable requirements.
- Task 1 deliverables: Plant-level standard-library and UDM PSS/E load flow (.raw) and dynamic models (.dyr) of the facility meeting the applicable requirements; supporting documentation.
Task 2: PSCAD Model Development
- Coordinate with you and the applicable OEMs to gather and review all supplied site-specific models.
- Clarify to the OEM what information will be required to meet Section 3 and Section 4 of the applicable requirements.
- Develop plant-level aggregated PSCAD model that meets applicable requirements.
- Configure the PSCAD model with controls, settings, and tuning specific for the proposed project to meet the performance requirements specified.
- Perform PSCAD model performance tests as outlined in Section 4 of the applicable requirements.
- Task 2 deliverables: Plant-level aggregated PSCAD model of the facility meeting the applicable requirements; supporting documentation.
- Note: If the PSCAD model provided by the OEM is generic (uses PSCAD standard library components), it is expected that the model response will deviate from the actual equipment performance. Care should be taken in use of generic models in the interconnection process and conclusions made from model quality test results performed using such models.
- Note: Model parameterization in Tasks 1 and 2 includes adjusting droop control parameters, PID controller gains of the PPC, voltage and frequency protection settings, and frequency and voltage control modes. The remaining model parameters are expected to be set by the OEM to reflect inverter performance closely.
Task 3: PSS/E Standard Library, PSS/E UDM, and PSCAD Model Validation and Benchmarking Report
- Document model quality checks and tests performed as part of Tasks 1 and 2, including benchmarking between model types.
- Perform the model quality and performance tests as outlined in Section 4 of the applicable requirements, and benchmark models across simulation platforms and domains in compliance with the applicable requirements.
- Complete the Model Checklist, with all applicable tests and test reports provided to you.
- Task 3 deliverables: Model Performance Attestation Report summarizing results of the model quality and performance tests (including benchmarking between model types); Model Checklist; supporting documentation.
Final deliverables
The following deliverables mirror those outlined in Appendix B of Southern Company's Model Submittal Requirements for Transmission Connected Inverter-Based Resources:
- PSS/E standard library model (power-flow models, dynamic models, and documentation).
- PSS/E UDM (power-flow models, dynamic models, and documentation).
- PSCAD model (project case file, other files necessary to run the case, and documentation).
- Model Performance Attestation Report.
- Model Checklist.
What we need from you
- Single-line diagram of the facility including the inverters, GSUs, main power transformer(s), shunt devices, and cable layout and lengths.
- Impedances of the cables for each cable type used for the collector system, impedance of GSUs, and main power transformer(s).
- If main power transformer(s) includes an online tap changer: details of tap settings, tap size, regulated bus with deadband ranges.
- Standard library and user-defined PSS/E dynamic models of the inverter, power plant controller, and dynamic reactive power devices provided by the OEM(s).
- PSCAD model(s) of the inverter, power plant controller, and any dynamic reactive power devices provided by the OEM(s). The inverter OEM should provide DC-side representation, which may include DC-DC converter(s).
- User manuals, datasheets, documentation, and attestations including instructions for setting up and running the PSS/E and PSCAD models, in support of meeting compliance with Southern Company requirements.
Assumptions and considerations
How the scope is bounded.
- PSS/E and PSCAD models are compatible with the applicable requirements.
- OEMs supply necessary attestation documentation or other applicable evidence as outlined in Item 12, Item 13, and Item 15 of Section 3 of the applicable requirements.
- It is assumed that the facility is a standalone unit (i.e., not part of a hybrid plant or co-located plant) and operating in grid-following mode.
- It is assumed that the facility does not include any more complicated cascaded PPC designs or other controls configurations beyond a conventional single inverter aggregate model and a single PPC model.
- We use engineering judgment and best practices where specific information is not available from you; the timeline assumes you supply all necessary information.
- Other information required to complete the scope of work for this project may be requested during the execution of this project, as deemed necessary.
- If OEM-supplied models are provided from multiple OEMs, it is assumed they are compatible with each other.
- Model quality issues are often uncovered when working with OEM-supplied models. This scope includes one round with the OEMs to address modeling deficiencies; further rounds are additional support, approved in writing.
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.