Study On Magnetic Field In Indoor Substation And Shielding Method

With the improving of people's life quality, higher life standard had been put forward to the quality of the life and working environment. The power-frequency electromagnetic fields in buildings are increasing paid attention by people. Therefore, we must study the model of electromagnetic environment within the buildings during buildings design and impart evaluation through quantitative calculationg. Effective measures should be taken to electromagnetic shielding to reduce many concerns of the people and a healthy living and working environment for people. Steady electromagnetic environment should be created to the normal operation of electronic equipments, which will produce favorable economic and social benefits.Considering infection of distribution around electromagnetic environment, measuring and simulation analysis are researched to existing distribution so as to providing mensurable reference materials for further indoor substation and assessment tools for the building electromagnetic environment analysis. The following work has been performed in this research:(1) According to the basic principles of finite element method and taking into account of three-phaes distribution busbars as the main power frequency magnetic field source, basic equation and condition of busbars model is deduced and discussed as eddy field.(2) Plate-type current busbars of indoor substation are studied using Maxwell software to calculate magnetic field in the space points. The paper emphasized on discuss on influencing factors of the busbars structure such as their length, spacing and breadth to magnetic inductive intensity. Feasible advises are put forward to reducing magnetic inductive intensity. The power frequency electromagnetic field distribution is analysed by measuring many substation and conclude that: three-phase power distribution room busbars is the main source of power frequency magnetic field; If distribution room surrounded by metal plates are closed, magnetic pollution will be greatly undermined; plate shielding effect is bigger then steel mesh.(3) Shielding materials, shielding methods of distribution-lines and shield efficiency of building construction reinforced-concrete are calculated using Maxwell software. We discuss impact of shielding parameters, shielding layer conductor diameter and mesh sizes to shielding efficiency and then measure to actual shielding efficiency. For a specific project example, The paper emphasize on discusses on magnetic field distribution of upper offices and weak electromotor room at the right side of transformer house, and effect of steel grids and steel types in the corresponding side walls was researched on shielding efficiency. Finally, feasible advises are put forward to increasing shielding efficiency aimed at these characteristics so as to reduce magnetic pollution surrounding the distribution and reduce electromagnetic interference to electron equipment and human health effect. Also some valuable conclusions to forecast and evaluate actual substations electromagnetic environment are advanced.(4) An software (EMPF) based on the method presented in this paper to compute electric field in substation is developed, which offer an easy model building compared with present commercial software.