The reason is the use of 1 harmonic rectifier, UPS power supply, electronic control equipment,fluorescent lamp system, computer, microwave ovens and other electrical and electronic equipment and electrical equipment. In these devices the use of the area, such as factory workshop,apartment buildings, residential, office, hotel, shopping mall, the harmonic pollution is very serious,the power quality decreased obviously. Especially the three harmonic line current would have a particularly high, even more than the current value, thus the service life of the electrical equipmentis reduced, the grid is overheating, and even may cause fire.

2 to the power grid risk mainly has: the power loss increase, shorten the life of the equipment,earthing protection malfunction, remote control function disorder, grid overheating. The power station, the harmonic caused by electronic device malfunction, the capacitor, the additional magnetic field, the neutral line overload and ignition of cable.

3 management measures. Is mainly to develop the relevant standards, including harmonicequipment requirements; harmonic analysis of existing power grid and the power grid, power grid structure of local recombination; separation the harmonics of the equipment, the use of filter.

The 4 harmonic and improve power quality is the first, followed by the energy saving. Harmonic management is a comprehensive management process, on the one hand is to start from the source, strengthen equipment management

To prevent the harmonic generation, the more important one is to raise awareness, active harmonic control, prevent disasters.