NERC PRC-012-2 Compliance for Solar, Wind and Battery Energy Storage Systems (BESS): What Generator Owners Must Know

Introduction

As renewable energy penetration increases across North America, the reliability of the Bulk Electric System (BES) depends more than ever on the coordinated operation of generation resources. Solar plants, wind farms, and large Battery Energy Storage Systems (BESS) are now critical contributors to grid stability. Because these resources can be automatically tripped or curtailed during system contingencies, they are often integrated into Remedial Action Schemes (RAS) designed to prevent cascading outages.



The North American Electric Reliability Corporation (NERC) developed Reliability Standard PRC-012-2 Remedial Action Schemes to ensure these schemes are properly designed, analyzed, tested, and maintained. The standard establishes compliance requirements for entities that own or operate RAS components within the BES.

For renewable generation developers and operators, the most important question is:

When does a solar plant, wind facility, or BESS become subject to PRC-012-2?

The answer depends on whether the Generator Owner (GO) is considered a RAS-entity.

This article provides a comprehensive technical overview of PRC-012-2 and explains:

• when renewable facilities become RAS-entities
• what obligations apply to Generator Owners
• how PRC-012-2 interacts with transmission-level RAS designs
• how solar, wind, and BESS facilities must maintain compliance
  

Understanding Remedial Action Schemes (RAS)

A Remedial Action Scheme is an automated system designed to detect predetermined power system conditions and execute corrective actions to maintain grid reliability.

Typical corrective actions may include:

• tripping generation
• shedding load
• opening transmission lines
• reconfiguring network topology
• reducing power flows
• curtailing renewable generation

RAS are typically implemented to address conditions such as:

• thermal overloads
• voltage instability
• angular instability
• cascading outages
• N-2 or N-x contingencies

Unlike protection systems that respond to faults, RAS operate based on system-level reliability conditions.

Examples of RAS actions involving renewable resources include:

• automatic tripping of solar plants when transmission paths overload
  
• wind generation curtailment during N-2 contingencies
  
• battery discharge limitations during voltage stability events
  
• generation rejection schemes triggered by line outages

These automated actions help prevent widespread grid disturbances.

Applicability of PRC-012-2 to Renewable Generator Owners

PRC-012-2 applies to three functional entities:

1. Reliability Coordinators (RC)
2. Planning Coordinators (PC)
3. RAS-entities

For solar, wind, and BESS operators, the relevant category is RAS-entity.

A RAS-entity is defined as:

The Transmission Owner, Generator Owner, or Distribution Provider that owns all or part of a Remedial Action Scheme.



This means a renewable facility is not automatically subject to PRC-012-2 simply because it generates power.

Instead, the Generator Owner becomes applicable only when it owns part of a RAS

When Solar, Wind, or BESS Plants Become RAS-Entities

A renewable facility becomes a RAS-entity if it owns equipment that performs any part of a remedial action scheme.

Examples of GO-owned RAS components may include:

Protection and Control Equipment

• relays executing RAS commands
  
• PLC or RTU logic implementing scheme actions
  
• breaker control circuitry

Communications Infrastructure

• fiber optic channels used for RAS signals
  
• microwave or telecom circuits
  
• redundant communication paths

Control Systems

• inverter control interfaces receiving RAS commands
  
• plant controllers implementing curtailment
  
• SCADA control paths
• Physical Trip Equipment

Physical Trip Equipment



• collector system breakers
  
• point-of-interconnection breakers
  
• feeder trip circuits

Even if the transmission owner or utility designs the scheme, ownership of these components makes the GO a RAS-entity.

In many interconnection agreements, renewable facilities participate in RAS programs designed by transmission operators to mitigate contingency risks on constrained transmission corridors.

Examples include:

• generation rejection schemes
• centralized RAS systems
• curtailment schemes
• load-generation balancing schemes
  

Typical RAS Architecture for Renewable Plants

A simplified RAS architecture may include:

  1. System monitoring system

• state estimator
• power flow monitors
• contingency detection

  2. RAS logic processor

• evaluates system conditions
• selects resources for corrective action

  3. Communication channels

• fiber or microwave
• redundant paths

  4. Site-level relay or controller

• receives RAS signal
• executes plant trip or curtailment

  5. Plant breaker or inverter control

• isolates generation
• reduces output

Renewable facilities commonly implement these functions using:

• GE Multilin relays (N60, L90)
• SEL protection relays
• plant SCADA controllers
• PLC automation systems
• communications gateways
  

PRC-012-2 Requirements for Generator Owners

If a solar, wind, or BESS facility becomes a RAS-entity, the Generator Owner must comply with the following PRC-012-2 requirements:

• R1
  
• R3
  
• R5
  
• R6
  
• R7
  
• R8

These requirements govern the full lifecycle of a remedial action scheme.

Requirement R1 – Notification Before RAS Changes

Generator Owners must provide documentation before:

• placing a new RAS in service
• functionally modifying a RAS
• retiring a RAS

The documentation must be submitted to the reviewing Reliability Coordinator.

The information package must include:

• RAS functional description
  
• system conditions that trigger the scheme
  
• actions performed by the scheme
  
• contingency studies supporting the design
  
• single-point failure analysis
  
• scheme diagrams and one-line drawings
  
• communications architecture
  
• protection coordination
  
• functional testing procedures

For renewable facilities, this requirement may be triggered when:



• modifying relay logic
• changing communication paths
• updating plant trip logic
• installing new RAS relays
• adding redundancy
  

Requirement R3 – Resolve Reliability Coordinator Issues

If the Reliability Coordinator identifies reliability concerns during review of a RAS design or modification, those issues must be resolved before the RAS is placed into service.



Examples of issues may include:

• inadequate redundancy
  
• insufficient communication reliability
  
• improper coordination with protection systems
  
• excessive response times
  
• security vulnerabilities

Generator Owners must coordinate with the Transmission Owner or utility to address these issues.

Requirement R5 – Analyze RAS Operations

One of the most significant operational requirements is post-operation analysis.

Within 120 calendar days of a RAS operation or failure to operate, the RAS-entity must participate in an analysis that determines:

• whether system conditions correctly triggered the scheme
  
• whether the scheme responded as designed
  
• whether the scheme mitigated the reliability issue
  
• whether unintended system responses occurred

Examples of events requiring analysis include:

• successful RAS generation trip
  
• failure of plant relays to trip when commanded
  
• communication failure preventing RAS operation
  
• inadvertent operation of plant trip circuits

If deficiencies are identified, they must be reported to the Reliability Coordinator.

Requirement R6 – Corrective Action Plan Development

If a deficiency is identified during:



• RAS operation analysis
• functional testing
• planning studies

the RAS-entity must develop a Corrective Action Plan (CAP) within six months.

The CAP must include:

• root cause analysis
  
• corrective measures
  
• implementation timeline
  
• responsible entities

For renewable plants, common CAP scenarios include:

• relay replacement
  
• communication system upgrades
  
• logic corrections
  
• SCADA interface improvements
  

Requirement R7 – Implement Corrective Actions

Generator Owners must implement the CAP and notify the Reliability Coordinator when corrective actions are completed.

Implementation activities may involve:

• relay firmware updates
  
• communications repairs
  
• breaker control wiring corrections
  
• SCADA configuration updates
  
• RAS logic improvements

All implementation steps must be documented for compliance evidence.

Requirement R8 – Functional Testing of RAS

RAS must undergo periodic functional testing to verify correct performance.

Testing intervals are:

• Every 6 years for non-limited impact RAS
  
• Every 12 years for limited-impact RAS

Testing must confirm:

• correct detection of system conditions
  
• proper processing of signals
  
• correct plant response
  
• communication integrity
  
• breaker or inverter response

Testing may include:

• end-to-end scheme simulation
  
• segmented subsystem testing
  
• relay injection testing
  
• SCADA control verification

Actual RAS operations can sometimes count as partial testing evidence.

Role of Planning Coordinators and Reliability Coordinators

While Generator Owners perform operational tasks, two other entities play major roles:

Unique Considerations for Renewable Plants

Renewable facilities introduce additional considerations for RAS implementation.

Solar Plants

Solar RAS actions may include:

• inverter tripping
  
• plant curtailment
  
• feeder isolation
  
• POI breaker trip

Because solar plants use centralized plant controllers, RAS actions often interact with inverter control systems.

Wind Farms

Wind farms typically involve:

• turbine-level controls
  
• collector system breakers
  
• plant controller curtailment commands

RAS design must consider turbine ride-through capabilities and control delays.

Battery Energy Storage Systems (BESS)

BESS RAS actions may include:

• stopping discharge
  
• stopping charging
  
• inverter trip
  
• PCS shutdown

Because BESS can respond quickly, they are increasingly used as fast-acting RAS resources.

Compliance Best Practices for Renewable Generator Owners

Generator Owners should implement the following compliance practices:

1. Maintain detailed documentation of RAS components.
2. Track relay configuration and firmware updates.
3. Maintain communication system reliability.
4. Record all RAS operations and alarms.
5. Conduct periodic functional testing.
6. Maintain coordination with transmission operators.
7. Preserve evidence of compliance activities.

How Keentel Engineering Supports PRC-012-2 Compliance

Keentel Engineering provides comprehensive support for RAS compliance and renewable integration.

Our services include:

• RAS engineering design
  
• RAS compliance assessments
  
• relay configuration and testing
  
• communication system design
  
• post-event analysis
  
• corrective action plan development
  
• functional testing programs
  
• NERC audit preparation

With deep expertise in renewable interconnection and NERC compliance, Keentel Engineering helps solar, wind, and BESS developers maintain full compliance while ensuring reliable grid integration.

Technical FAQ – PRC-012-2 and Renewable Generator Owners

Final Thoughts

Solar, wind, and battery storage facilities must understand their potential role within these schemes and ensure compliance with NERC PRC-012-2 whenever they own RAS components.

With careful design, testing, and coordination, renewable facilities can support grid stability while meeting regulatory obligations.