ERCOT NOGRR 245: The Complete IBR Compliance Guide for Texas Generator Owners

If you own or operate an inverter-based resource connected to the ERCOT transmission system, NOGRR 245 (Nodal Operating Guides Revision Request 245) is the most consequential compliance document you need to understand in 2025. Implemented to address ERCOT’s growing reliability concerns about IBR performance during system disturbances, NOGRR 245 establishes ride-through, reactive support, and model validation requirements that go beyond the baseline NERC PRC-029-1 standard in several important ways.

What Is NOGRR 245?

NOGRR 245 is an ERCOT protocol revision that introduced specific performance requirements for IBRs (solar PV, wind, and BESS) interconnected to the ERCOT grid. It was developed in response to multiple disturbance events in which IBRs tripped offline in large numbers during voltage and frequency events, creating reliability risks that ERCOT’s planning assumptions had not fully anticipated.

Key provisions of NOGRR 245 include:

Voltage Ride-Through Requirements: IBRs must remain online during voltage sags to defined levels for defined durations, consistent with NERC PRC-029-1 but with ERCOT-specific implementation details.

Reactive Current Injection During Voltage Disturbances: During low-voltage events, IBRs must inject reactive current at a minimum rate (typically 2% of rated reactive current per 1% voltage deviation) to support ERCOT system voltage.

Active Power Recovery Requirements: Following fault clearance, IBRs must recover active power output at a defined rate (MW/second) to restore system frequency response.

Frequency Response Requirements: IBRs must provide a governor-like active power response to frequency deviations, contributing to ERCOT Primary Frequency Response (PFR) obligations.

Model Quality Test (MQT) Requirements: Generator owners must conduct periodic field tests of their IBR’s ride-through and response performance, compare results to simulation models, and update models where discrepancies exceed defined tolerances.

The ERCOT Model Quality Test (MQT) Process

The MQT is the most technically distinctive element of ERCOT’s IBR compliance program. Unlike NERC MOD-026-2, which primarily validates steady-state AVR behavior, the ERCOT MQT directly tests dynamic ride-through and response performance under conditions that approximate actual grid disturbances.

MQT Test Types

Voltage Step Test: A step change in plant-level voltage setpoint tests the IBR’s reactive power response characteristics.

Active Power Step Test: A step change in active power setpoint tests governor-like active power response speed and accuracy.

Frequency Droop Test: A synthetic frequency deviation is applied to assess the IBR’s frequency response function.

Low Voltage Ride-Through Test: Where feasible, a controlled voltage depression is applied to verify ride-through capability and reactive current injection response.

MQT Testing Logistics

ERCOT MQT tests are typically performed:

• Following initial commercial operation (commissioning test)
• Following significant plant modifications that affect dynamic performance
• On a periodic schedule established by ERCOT (approximately every 5 years)
• Following disturbance events where the plant’s behavior was inconsistent with model predictions

Test planning, data recording, and post-test analysis require coordination between the generator owner, the inverter OEM, and the ERCOT market operator. American Power Engineers supports clients through the complete MQT process, from test plan development through final model submission to ERCOT.

NOGRR 245 and ERCOT Interconnection Requirements

New ERCOT-connected IBR projects must demonstrate compliance with NOGRR 245 requirements as part of the Generator Interconnection Agreement (GIA) and commissioning process. This means:

Pre-Interconnection Verification: Before synchronizing to the ERCOT grid, the generator owner must submit documentation demonstrating that the facility’s protection and control systems are configured to meet NOGRR 245 ride-through and response requirements.

Commissioning Testing: Initial MQT tests must be conducted during the commissioning period, with results submitted to ERCOT for review and model database update.

Ongoing Compliance: Generator owners must maintain their facilities in compliance with NOGRR 245 on an ongoing basis, including periodic MQT retesting and model updates.

Our POI interconnection engineering team has extensive ERCOT interconnection experience and can support your facility through the complete NOGRR 245 compliance lifecycle.

Reactive Capability Requirements for ERCOT

ERCOT’s reactive capability requirements for IBRs include specific provisions for reactive capability testing that differ from other ISO/RTO territories:

Reactive Capability Assessment (RCA): ERCOT requires generator owners to submit detailed documentation of their facility’s reactive capability at the POI, including the Q-P capability curve and the reactive capability under all operating modes.

Seasonal Capability Reporting: ERCOT requires seasonal updates to reactive capability reporting, reflecting changes in capability as temperature affects transformer ratings and inverter ratings.

Reactive Capability Test: ERCOT may require field testing to verify reported reactive capability, particularly following equipment modifications or in response to reactive capability shortfalls identified during system operations.

How American Power Engineers Supports ERCOT NOGRR 245 Compliance

Our Texas-experienced team provides:

NOGRR 245 Gap Assessment: Rapid identification of compliance gaps in existing ERCOT-connected IBR facilities, with prioritized remediation recommendations.

MQT Test Planning and Execution: Complete support for ERCOT Model Quality Test planning, test procedure development, data recording, and post-test analysis.

EMT Model Development: PSCAD-based EMT model development and validation for ERCOT model database submission, meeting ERCOT’s specific format and validation requirements.

Protection Settings Review: Comprehensive review of all protection system settings against NOGRR 245 requirements, including inverter firmware, plant-level relays, and interconnection protection.

GIA Compliance Documentation: Preparation of the technical compliance documentation required by ERCOT and the applicable Transmission Service Provider (TSP) for project interconnection.

Contact American Power Engineers for ERCOT NOGRR 245 compliance support, or learn about our NERC compliance services.

Related Articles:

• NERC PRC-029-1 IBR Compliance
• IEEE 2800-2022 IBR Compliance
• NERC MOD-026-2 Model Validation