Table of Contents

1 Overview
   1.1 Scope
   1.2 Purpose
2 Normative References
3 Description of system conditions addressed in this guide
4 Normal and abnormal frequency operation of electrical power
   systems and its effect on equipment in the system
   4.1 Power system dynamic
   4.2 Abnormal frequency operation of power systems
5 Underfrequency load shedding and restoration philosophy
6 Underfrequency load shedding methods
   6.1 Manual/SCADA load shedding
   6.2 Automatic load shedding
   6.3 Local
   6.4 Wide area underfrequency load shedding
7 Load restoration methods
8 Frequency relays, measuring principles, and characteristics
   8.1 Electromechanical relays
   8.2 Solid-state (static) relays
   8.3 Microprocessor (digital) relays
9 Operating principles
   9.1 Fixed frequency
   9.2 Rate of change of frequency df/dt
   9.3 Average rate of change f/t
10 Scheme design
   10.1 Dependability and security
   10.2 Redundant frequency relays sensing multiple voltage sources
   10.3 Current and voltage supervision
   10.4 Directional power supervision
   10.5 Rate-of-frequency-change supervision
11 Effects of voltage change on frequency load shedding
12 Existing frequency load shedding and restoration practices
   12.1 NERC: 2003 underfrequency load shed criteria
   12.2 Nordel underfrequency load shed criteria
   12.3 France, Electricite de France underfrequency load shedding
   12.4 Ireland, Electricity Supply Board underfrequency load
        shedding and automatic frequency restoration
   12.5 Industrial applications
13 Setting and performance criteria
   13.1 Performance criteria
   13.2 Setting guidelines for abnormal frequency load shedding
14 Maintenance, testing, and reliability
   14.1 Frequency protection elements
   14.2 Rate-of-change elements
   14.3 Average rate-of-change elements
   14.4 Testing of load shedding schemes
   14.5 Testing of load restoration schemes
15 Examples
   15.1 Practical application of load shedding
   15.2 Historical examples of underfrequency load shedding
        during system disturbances
Annex A (informative) Bibliography

Abstract

Describes abnormal frequency power system behavior, existing load shedding and restoration practices, the abnormal frequency function of typical protective relays, and possible new methods for improved load shedding and restoration.

General Product Information

Published
Document Type	Standard
Status	Current
Publisher	Institute of Electrical & Electronics Engineers
Pages
ISBN
Supersedes	IEEE DRAFT C37.117 : D7 2006