Generator and Transformer Protection

Electric power systems are designed to serve loads in a safe and reliable manner. One of the major considerations in the design of any power network is adequate control of short-circuits or “faults” as they are generally referred to. If faults are not controlled they can cause unnecessary loss of electricity service with all of its many ramifications and damage to equipment. Faults on system elements are removed from networks by means of equipment referred to as “Power System Protection”.

This course is designed to give delegates a broad understanding of the nature of power network faults and the principles of Protection System Protection, Design, Operation and Maintenance.

Course Objectives

On completion of the course the trainee(s) will be competent in:

• The skills involved and the principles applied to power system protection
• Interpreting system faults from protection system alarms and indications and determine the necessary corrective actions
• Information and instruction in safe operating procedures in electrical protection schemes, including elements of maintenance of HV and LV protection relay systems

Course Outline

DAY ONE

• Introduction and General Philosophies
• Introduction
• Classification of Relays
• Protective Relaying Systems and Their Design
• Applying Protective Relays
• Relays and Application Data
• Circuit-Breaker Relays Comparison of Symbols

Technical Tools of the Relay Engineer: Phasors, Polarity, and Symmetrical Components

• Introduction
• Phasors
• Polarity in Relay Circuits
• Faults on Power System
• Symmetrical Components
• Symmetrical Components and Relaying

DAY TWO

• Basic Relay Units
• Introduction
• Electromechanical Units
• Sequence Networks
• Solid-State Units
• Basic Logic Circuits
• Microprocessor Architecture

Instrument Transformers for Relaying

• Introduction
• Current Transformers
• Equivalent Circuit
• Estimation of Current Transformer Performance
• European Practice
• Direct Current Saturation
• Residual Flux
• MOCT
• Voltage Transformers and Coupling Capacitance Voltage Transformers
• Neutral Inversion

DAY THREE

• Microprocessor Relaying Fundamentals
• Introduction
• Sampling Problems
• Aliasing
• How to Overcome Aliasing
• Choice of Measurement Principle
• Self-Testing

System Grounding and Protective Relaying

• Introduction
• Ungrounded Systems
• Reactance Grounding
• Resistance Grounding
• Sensitive Ground Relaying
• Ground Fault Protection For Three-Phase, Four-Wire Systems

DAY FOUR

Generator Protection

• Introduction
• Choice of Technology
• Phase Fault Detection
• Stator Ground Fault Protection
• Backup Protection
• Overload Protection
• Volts Per Hertz Protection
• Over speed Protection
• Loss-of-Excitation Protection
• Protection Against Generator Motoring
• Field Ground Detection

DAY FIVE

• Transformer and Reactor Protection

• Introduction

• Magnetizing Inrush

• Differential Relaying for Transformer Protection

• Sample Checks for Applying Transformer Differential Relays

• Typical Application of Transformer Protection

• Protection of Phase-Angle Regulations and Voltage Regulators

• Zigzag Transformer Protection

• Protection of Shunt Reactors

Course Methodology

A variety of methodologies will be used during the course that includes:

• (30%) Based on Case Studies
• (30%) Techniques
• (30%) Role Play
• (10%) Concepts
• Pre-test and Post-test
• Variety of Learning Methods
• Lectures
• Case Studies and Self Questionaires
• Group Work
• Discussion
• Presentation