The control of harmonic currents is not a new subject. It has been
theoretically and experimentally investigated for more than fifty years. In
1974, after static power converters had been in use about ten years and
promised to be increasingly used in industry and home, the IEEE formed a
committee to develop a guide for harmonic control and reactive compensation of
static power converters. This work was published in April 1981 as IEEE
Standard 519-1981, Reference 11.
The IEEE standard lists problems caused by harmonics as:
(1) Inductive coupling between AC power lines and telephone lines
(2) Excessive heating of solid rotors in synchronous machines that limits
the amount of converter load that can be carried by synchronous
(3) Erroneous operation of control and regulating circuits caused by noise
from harmonic generation
(4) Interference with TV video circuits
(5) Erroneous operation of induction disk devices such as watt-hour meters
and overcurrent relays
(6) Torque pulsations on AC motors that may be harmful to the process or
may set up resonant conditions of the mechanical system
(7) Excessive heating and failure of ballast capacitors used in fluorescent
or mercury lighting
(8) Upset of carrier systems that control remote devices.
The standard recommends that the voltage distortion on general power
systems not exceed 5% to avoid these problems. A graph is provided that helps
estimate the harmonic voltage distortion as a function of short-circuit ratio.
The short- circuit ratio is defined as the power system short circuit
volt-amperes (VA) divided by the load wattage. For 6-pulse rectification, the
standard predicts 5% harmonic distortion for a load that is 33% of the
short-circuit capacity of the system. Using 12-pulse rectification only gives
a slight improvement, 38% of the short-circuit capacity.
The solutions for reducing harmonic currents recommended by the standard
include shunt filters, phase multiplication and harmonic compensation or
The standard contains considerable information on how to calculate and
measure harmonic disturbances, recommended design practices and a 192-item
bibliography on power factor, harmonics and EMI.
The IEC is also working on a document, "Disturbances in Supply System
Caused by Household Appliances and Similar Electrical Equipment, Part 1:
Harmonics," Third draft, IEC, Technical Committee No. 77, reported in
Reference 5. This document is similar to the European