1 our country on harmonic problems of late, started in the late eighty 's, the significance of the study firstly because of harmonic harmonic harm is very serious. To reduce the harmonic in thepower transmission and utilization, production efficiency, is the electric heating equipment, noise and vibration, and makes the insulation aging, shorten life, and even burned. Power system harmonics will cause partial parallel resonance and series resonance, enlarge the harmonic content, caused by capacitor equipment burning. Harmonic can also cause the maloperation ofrelay protection and automatic device, the electric energy metering and confusion, resulting in direct economic losses.

2 harmonic research significance lies in its effects on the development of power electronics technology, power electronics technology is an important pillar of the future development of science and technology. However, the harmonic pollution produced by power electronic devices has become an obstacle to the development of power electronics technology barrier, it forcesresearchers to governance of harmonics are more effective study.

The 3 harmonic research significance is that it is environmental pollution, protect the green environment. Power supply network of electric power system, harmonic is the main symbol of"green".