Advanced System Protective Relays

Protection of low, medium and high voltage power systems requires an understanding of system faults and their detection, as well as their safe disconnection from the power system. This course presents a comprehensive and systematic description of the concepts and principles of operation and application of protection schemes for various power system elements such as feeders, transformers, motors, buses, generators, etc. The course begins with an overview of power system faults and the protection scheme requirements for the detection and coordinated clearance of these faults. Protection requirements for cogeneration, non-utility generation, and interconnection with the utility power system are covered in detail. This course deals with protection systems from a practical perspective, and includes important functional aspects such as testing and coordination of protection systems. It is specially designed for industries and utilities, which depend on proper system protection for operational efficiency and minimizing damage to equipment.

Course Objectives

To provide a practical understanding of protective schemes for electrical power systems and equipment.

You will be able to:

• USE your knowledge of the basic industrial and utility system protection techniques include fault analysis
• FURTHER your understanding of protective devices being used in your organization
• DETERMINE your own relay settings and thoroughly understand the philosophy of protective systems
• RELATE TO actual cases illustrating various techniques in present use and highlighting particular approaches used by experienced system designers
• APPLY your awareness of recommended practices in applying or approving protection schemes
• UNDERSTAND problems generally faced and solutions successfully adopted by industry
• CALCULATE the basic fault currents flowing in any part of the electrical system
• IMPROVE your electrical systems protection against faults and over voltages
• SELECT and apply microprocessors-based multi-function relays

Course Outline

Power System Faults

• Different types of faults
• Incidence of faults on power system equipment
• Effects of power system faults
• Magnitude of fault current
• Detection of faults
• Clearance of faults
• Requirements of protective relaying systems

Components of Power System Protection Schemes

• Fault-detecting relays
• The transition from electro-mechanical relays to electronic and digital microprocessor-based relays
• Tripping relays and other auxiliary relays
• The application of programmable logic controllers
• Circuit breakers - bulk oil, air-blast, vacuum, SF6
• Current transformers
• Voltage transformers
• Modern microprocessor-based relays - review types available

Current Transformers (CT) and Voltage Transformers (VT)

• Various types of CTs, VTs and CVTs
• Theory and characteristics of CTs
• Application requirements of CTs for protective relaying
• Accuracy classifications
• Future trends in CT design using optics
• Testing of CTs and VTs

Feeder Over current Protection

• Protective relaying requirements for radial systems
• Elements of feeder protection schemes
• High-set, low-set and inverse-timed elements
• Coordination with other devices and fuses
• Various types of over current relay
• Electromechanical, electronic and digital relays
• Relay setting criteria
• Load limitations
• Testing of over current protection schemes
• Microprocessor-based feeder over current relays - features, application and testing

Coordination Of Electrical Protection Systems

• Fuse to fuse
• Circuit breaker to fuse
• Fuse to circuit breaker
• Computer software packages for protection coordination studies
• Auto-reclosing of circuit breakers
• Back-up protection
• Limitation of fault current
• Selective zones of protection

Switchboard And Bus Protection

• Types of bus protection schemes
• Basic concept of differential protection
• Application to various bus configurations
• Application to switchboards
• Testing of bus protection schemes

Motor Protection, Starting and Control

• Applicable motor standards
• Methods of starting
• Differential protection, phase unbalance, over current
• Ground fault protection
• Canadian Electrical Code requirements
• Microprocessor-based motor control and protection devices

Transformer Protection

• Over current and ground fault protection
• Application of differential protection to transformers
• Restricted ground fault protection
• Gas relays, pressure and gas accumulation
• Winding temperature and oil temperature devices
• Testing of transformer protection schemes
• Modern microprocessor-based multi-function relays - available functions, application and testing

Generator Protection

• Differential protection
• Reverse power, stator ground, out-of-step, loss of field, field ground, over excitation, interterm
• Over-frequency, under frequency, overvoltage, under voltage
• Negative phase sequence or phase unbalance
• Voltage controlled and voltage restricted over current protection
• Synchronizing systems, synchro-check relays
• Comparison of electro-mechanical and electronic relays
• Testing of generator protection schemes
• Microprocessor-based multi-function generator protection relays - available relays, application and testing

Transmission Line Protection

• Interconnected systems with two-way flow of fault current
• Distance or impedance protection schemes
• Phase comparison protection schemes
• Communication channel requirements between terminals
• Coordination and transfer-tripping between terminals
• Modern microprocessor-based line protection relays – available relays, features, applications and testing

Capacitor Protection

• Application of static capacitors on power systems
• Description of protection schemes used
• Testing of capacitor protection schemes
• Microprocessor-based capacitor protection and controls relays

Recent Developments and Future Trends in Protective Relaying

• Digital relays
• Integrated microprocessor based systems for control, monitoring, and protective relaying
• Optical current transformers
• Fiber optic communications

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