The common method to solve ferroresonance overvoltage in distribution network is to install microcomputer harmonic elimination device or primary harmonic elimination device.
Now there is a kind of flow sensitive harmonic eliminator on the market. The flow sensitive harmonic eliminator also belongs to primary harmonic eliminator. The flow sensitive harmonic eliminator technology adopts flow sensitive materials and is in a low resistance state under normal conditions. When resonance occurs, the exciting current of Pt primary winding increases and the resistance of flow sensitive harmonic eliminator increases abruptly, which has achieved the purpose of harmonic eliminator. The installation position is between the neutral point of the primary winding of the voltage transformer and the earth. Primary harmonic elimination is a pressure-sensitive electrical primary harmonic elimination made of silicon carbide (SIC); The flow sensitive primary harmonic elimination has thermal characteristics. With the increase of the flowing current, the resistance temperature will rise, the resistance value will increase rapidly, and the resonance state will be destroyed. Both primary harmonic eliminators manage ferromagnetic resonance through their own physical characteristics.
The microcomputer harmonic elimination device belongs to the secondary harmonic elimination device, which is usually installed on the instrument door of the switchgear in the high voltage room (usually Pt cabinet) and also on the secondary protection screen. So it is also called secondary harmonic elimination.
These are two different devices, both of which are designed to eliminate ferromagnetic resonance overvoltage in power system. Primary harmonic elimination and microcomputer harmonic elimination devices can also be installed for combined use, which needs to be determined according to the specific situation of the on-site distribution network, so as to give full play to the role of primary harmonic elimination and microcomputer harmonic elimination. The two cooperate with each other, complement each other, and eliminate various resonances in the power system.