Study On Mechanism And Application Of Inductive Filtering Transformer

With the improvement of the power grid capacity and the development of the power grid construction, the harmonic problem in power system is attracting more and more attention. The existence of harmonics directly leads to the increase of the vibration and noise of the main equipment in the grid, which will sure make the equipment loss increase. At the same time, the harmonics are possible to cause the elements in the grid appearing in series or parallel resonance, which will threaten the security and stability of the whole grid.At present, the common methods of filtering are all imperfect. In the second chapter, this paper introduces a new type of filtering method called inductive filtering. Inductive filtering is a novel method to suppress the influence of harmonics. In this novel method the connection method of the transformer secondary windings is extended delta connection. Between the two windings of the secondary winding a tap is extracted to access the inductive filtering device. This novel method can not only filter harmonics according to the change of the harmonics in the grid just like the active filter technology but also costs little.In HVDC systems, due to the existence of many converter and inverter devices, the harmonic problem is very obvious. Therefore, the research of inductive filtering application is mainly focused on HVDC system. In the third chapter, through the MATLAB/Simulink we built a traditional model of HVDC system and a novel model of HVDC system which uses the inductive filtering technology. We monitored the primary side current of A phase of the two models. In the traditional model the current distorted obviously and the waveform of the current of novel model is fluent, which proves that the inductive filtering has good effect in filtering. In this paper we also built the model of transformer silicon steel sheet through the software of ANSYS. Through analyzing the changes of magnetostrictive displacement caused by the harmonic of transformer silicon steel sheet, which proves the inductive filtering technology in transformer noise also has a good effect.AC+DC combined transmission technology is a novel technology, the iron core of AC+DC combined transmission network transformer is easily saturated because of the existence of DC current. In view of this situation, the common solution is to use the Z type transformer, but Z type transformer cannot be used widely because of its complex structure and high costs. This paper presents an intelligent inductive filtering technology, this novel technology can not only suppress the saturation of the transformer iron core, but also avoid the increase of current caused by redundancy inductive filtering device. We build the simulation model of AC+DC combined transmission system based on the intelligent inductive filtering technology, the simulation results verify the validity of this novel technology.