Collaborative effort between consultants and the ERCOT team.
Focus on testing grid forming battery energy storage systems (BESS).
Grid Forming Battery Technology
Technical functional specification and test framework developed.
Four EMT models from commercial devices extensively tested.
Functional definition and specification approach, avoiding specific control topologies.
Project Team and Background
Involved engineers from both consulting and ERCOT sides.
Team members from operations, planning, and ERCOT personnel acknowledged.
Previous experience with grid forming specification since 2021.
Grid Forming vs. Grid Following
Explanation of grid forming as maintaining a constant voltage phaser at the inverter terminals.
Grid following tightly controls active and reactive currents by synchronizing with the external grid.
Comparison of responses in island and grid-connected systems.
Benefits of Grid Forming Technology
Better performance in weak systems.
Damping of subsynchronous frequencies.
Enhanced voltage and frequency support.
Testing Framework
Four main test benches: Variable Impedance System (Single Machine Infinite Bus) , Double Battery, Variable Impedance System + series capacitor , and Perturbed Voltage Source.
Tests evaluate grid forming characteristics, stability, energy response, and damping.
IEEE 2800 compliance considerations.
Specific Tests and Objectives
Examples of tests: Loss of last synchronous machine, RoCoF tests, SCR step down with fault, angle step change, series compensation step test, energy response test, and frequency scan tests.
Some tests designated as pass/fail, others informational.
Tests designed to push inverters to their operational limits.
Challenges and Observations
Discussion on potential model improvements for grid following devices.
Interactions between grid forming and grid following devices not included in mandatory tests.
Importance of headroom and practical considerations for energy response.
Conclusion and Follow-up
Grid forming batteries show promising stabilization benefits.
Ongoing collaboration and future work anticipated.
Summary of OEMs’ performance and validation through tests.
3 - ERCOT Advanced Grid Support Inverter-Based ESR Assessment and Adoption Discussion - ERCOT, All - Fred Huang
ERCOT is in the early stages of assessing new inverter-based energy storage resources (ESRs) with advanced grid support capabilities.
Feedback and industry collaboration are highly encouraged to improve the process.
Upcoming proposals aim to set standards for advanced grid support inverter-based ESRs, focusing on functionality and performance.
Initial focus is on voluntary adoption of new standards, with mandatory adoption considered for the near future.
ERCOT has been in dialogue with various industry original equipment manufacturers (OEMs), including those from the wind and solar sectors, to gain insights and support.
Preliminary results indicate that inverter-based ESRs can enhance grid stability with minimal hardware impact.
Studies show positive impact on system stability, potentially increasing limits for existing Grid Transmission Constraints (GTCs).
Considering global trends and activities, ERCOT aims to adopt advanced grid support inverter-based ESRs starting with energy storage and expanding to wind and solar.
Tools and models will need to be accurately coordinated and monitored for optimal grid support.
Future steps include submitting a revision request for adoption and potentially creating a new ESR support framework.
Acknowledgement of collaborative efforts with academia and internal ERCOT teams in progressing this initiative.
Questions
Ryan Wu: Are there any considerations about the increased risk of islanding with grid forming adoption?
Answer: Currently under internal discussion with an emphasis on operating ERCOT as a single grid.
General Question: What's the timeline for protocol language adoption?
Answer: Plan to have protocol language by end of 2024, with potential for further group discussions before formal submission.
General Question: Is the work on specifications and testing finalized?
Answer: Electronics recommendation used as primary reference; internal reviews and potential adjustments based on feedback are ongoing.
5 - Draft DWG Procedure Manual Edits - John Schmall, Jonathan Rose - ERCOT, All
Follow-up presentation regarding NOGRR245 and IEEE 2800 changes.
Changes impact the DWG procedure manual, specifically voltage ride-through requirements.
DWG procedure manual is a key document for model quality testing (MQT).
Edits to the procedure manual incorporate new voltage ride-through curves from NOGRR245.
Updated manual is available on the ERCOT Dynamics Working Group webpage.
Presenting and seeking approval for language updates at the August ROS meeting.
Reconciling old legacy curves with new preferred curves in the updated manual.
Addressing modeling of switch shunts, transformer tap controllers, and testing for low/high voltage ride-through (LVRT/HVRT).
Requesting additional details in the table format to document equipment capabilities.
Ensuring alignment of provided models with actual operational practices and capabilities.
Next steps: ERCOT intends to review comments from stakeholders before moving forward.
Key Comments:
Request for stakeholders to provide comments within a week, potentially extending the deadline to allow more time for review.
Stakeholders expressed concerns over time for reviewing complex changes.
ERCOT agreed on extending the comment deadline to around July 24, with a target post date by July 26.
Discussion on when new ride-through profiles from NOGRR245 would be effective.
Questions Addressed:
Clarification on minor voltage changes and active power injection requirements.
Details about the speed and control of transformer tap settings and initialization scripts.
Requirement to model transformer tap controllers despite their time delay.
Acknowledgement of the implementation date and procedural nuances for NOGRR245.
Steven Solis deferred his item to the next meeting.
There was a discussion item from March ROS related to reclosing close to IBRs. This will be discussed in the SPWG meeting on the 17th and will be brought to the August agenda.
A market notice has been issued about switching to a single resource battery model starting from August 6, which will also be discussed in the next IBRWG meeting.