Simulation of the Electromagnetic Response Characteristic of an Inductively Filtered HVDC Converter Transformer Using Field-Circuit Coupling

A field-circuit coupling computation method is proposed in this paper to reveal the special electromagnetic characteristic of a novel inductive filtering (IF) method applied in high-voltage direct current (HVDC) converter station. The new converter transformer is modeled by using 3-D finite-element method, and the surrounding fully tuned branches, for creating precondition of implementing the IF method, are modeled by using the coupled circuits. The harmonic characteristic of the load-side current is modeled by using mixed harmonic current sources. The parameter design of the coupled circuit is also performed for the coupling model. Following this, based on the established coupling model, the multiphysical characteristics (e.g., electric field, magnetic field, excitation characteristic, and core losses) are analyzed in detail. The system simulation and the experimental results validate the modeling method. All of the research results indicate that the IF method can greatly reduce the harmonic currents in the grid winding, can improve the excitation performance, can improve the electromagnetic environment, and can reduce the harmonic losses of the HVDC converter transformer.