Study of AC and DC Electromagnetic fields around innovative busbar arrangement for HVDC bipolar stations

The Thesis work is a study of the electro-magnetic field inside an HVDC converter station, focusing on some particular areas. Three are the main parts of the analysis: the area between the common coupling point and the transformers, the busbar between transformers and reactors and the reactors. In the first part of the Thesis, there is an overview of the HVDC technology, analysing the main parts of a station, a state of art of the VSC technology and the theorical approach for the study of the electro-magnetic field. There is also an introduction of the three software used for the simulations. Comsol is the first software, based on a numerical method to analyse the electric and magnetic field. Magic and the internal software of Politecnico di Torino, instead, are based on an integral method to analyse respectively the magnetic field and the electric field. In the second part of the Thesis, the three software are compared, at a distance of 1m to the bars and 1.5m to ground, to see if there are any significant differences. The values obtained, giving the necessary considerations due to the different conditions of each simulation, are similar to one another. Each study is different: the area between the common coupling point and the transformers has only the AC component, so there is only one AC study; the reactor and the busbar between transformers and reactors have both the AC component, flowing from the transformer, and the DC component, flowing from the valve hall. In this case, the study is divided into two separate analysis, one for the AC component and one for the DC component, then added together using the superposition of effects. In the third part of the Thesis, there is the study of the electro-magnetic field at a distance of 1.7m to ground, according to the legal limitations. In this part there is an overview of the actual values of the electric and magnetic fields legally allowed, the study of the fields and a final chapter, consisting of a list of possible safety solutions to reduce the fields or to make the environment safe for the people who may be inside the station.