System Protection and Control

Generator Protection Upgrades

Many generators still operate with electromechanical or first-generation microprocessor relays that no longer meet current reliability standards or manufacturer support. TWC supports protection upgrades to modern microprocessor-based relays, including relay selection, settings development, and coordination with existing protection schemes.

• Relay selection and specification support
• Protection settings development and documentation
• NERC PRC standard compliance verification for new settings

AVR Upgrades

Automatic voltage regulator (AVR) and PSS upgrades are necessary to maintain generator reliability as existing infrastructure passes its end of life. Older AVR platforms may lack OEM support and pose challenges with replacement if the device fails. TWC provides engineering support throughout the upgrade process.

• Specification of AVR and design of any retrofits required
• Installation support and commissioning tests
• Post-upgrade compliance assessments for standards like PRC-019, MOD-026, and VAR-501

Protection Coordination Studies

Protection systems at generating facilities must coordinate across multiple zones (from the generator terminals through the step-up transformer and into the collection system) to ensure faults are isolated quickly and selectively. TWC performs protection coordination studies and develops protection system designs for new and existing facilities.

• Short-circuit analysis and fault current calculations
• Relay coordination across protection zones
• PRC-027 protection coordination assessments

Reactive Power Compensation Studies

Reactive power capability and voltage support are central to generator interconnection requirements and NERC compliance. TWC performs reactive power studies to evaluate facility capability, identify compensation needs, and support utility and ISO requirements for reactive power.

• Generator and plant reactive power capability assessment (MOD-025)
• Reactive compensation sizing and placement
• Voltage support analysis for interconnection requirements

Load Flow Studies

Load flow studies establish the steady-state operating conditions of a facility and are foundational to protection settings development, interconnection studies, and compliance assessments. TWC performs load flow analysis for both new facilities and existing sites undergoing configuration changes.

Harmonics, Transient Overvoltage, and TRV Studies

Switching transients, transient recovery voltages (TRV), and harmonic distortion can cause equipment damage and protection misoperation when they're not accounted for in equipment specification and protection design. TWC performs pre- and post-interconnection harmonics studies and transient studies to support equipment specification and protection design.

• Pre- and post-interconnection harmonics analysis
• Transient overvoltage (TOV) studies
• Transient recovery voltage (TRV) analysis