Inductive Filtering Technology Research Articles

A Four-Winding Inductive Filtering Transformer to Enhance Power Quality in a High-Voltage Distribution Network Supplying Nonlinear Loads

This paper solves the problem of reactive power and harmonics compensation in a high-voltage (HV) distribution network supplying nonlinear loads. An inductive filtering (IF) approach where passive filters connect to the filtering winding of a four-winding inductive filtering transformer (FW-IFT) is presented to enhance the power quality of the public grid. This method can not only greatly suppress harmonic currents of the medium and/or low-voltage (LV) side, but also prevent them from flowing into the public grid. The new main circuit topology, where the FW-IFT has specific filtering winding by adopting the ampere-turn balance of the transformer, is presented. On the basis of the structure of the FW-IFT, the magnetic potential balanced equation and inductive filtering technology, its equivalent circuit and mathematical model are established, and the filtering performances are analyzed in detail. Simulation and experimental results rated at SN-10/0.38 of the FW-IFT are presented to prove the efficacy of the comprehensive enhancement of power quality on the grid side.

Vibration and noise characteristics of the inductive filtering converter transformer

Harmonic magnetic fluxes in transformer's core and harmonic currents in grid-side winding can be restrained via the inductive filtering technology. Vibration and abating noise of the core caused by the harmonic magnetic fluxes are controlled at the source, and has a good effect in reducing vibration and abating noise of the grid-side winding. Vibration and noise characteristics of the inductive filtering converter transformer are tested under load. The experimental results verify this theory.

Noise characteristics of the new converter transformer under DC bias

Harmonic magnetic fluxes in transformer's core and harmonic currents in grid-side winding can be restrained via the inductive filtering technology, and running noise of the transformer is reduced at the source. The A-weighted sound levels of the measuring points are measured under DC bias. The noise test results verify this theory. When the fully-tuned filters matched with the new converter transformer are inputted and not inputted, the noise response curves of the measured points are compared. The fitting coefficients of the noise values at 1250 and 1600 Hz with the unbalance degrees of the trigger angle are obtained.

A Novel Method of Core Saturation Suppression for the AC+DC Distribution Network Transformer

With the rapid development of smart grids, the interconnection between the grid and distributed renewable energy is the inevitable trend of future study. Because of the existence of the DC source in the combined AC-DC distribution network, the transformer iron core is easily saturated generating lots of harmonics and increasing the loss of the transformer. This paper presents a novel method based on inductive filtering technology of core saturation suppression of the transformer in the combined AC-DC distribution network, this novel method can suppress the harmonics caused by the flux saturation and forbid the harmonics intruding into the ac grid. In the end we build the simulation model to prove the correctness and practicability of this novel method.