Study Of Magnetic Field Of Air-core Reactors Using Small-scale Experimental Technique

In the last decade the high voltage high power air-core reactors are widely used in modern electric power systems, which play an important role. However, these devices are able to emit high magnetic fields, making them one of the main sources of magnetic fields in substations. They may not only produce potential unwanted health threats on both nearby residents and on working staff, but also have electromagnetic influences on electric devices in the vicinity. Therefore, the magnetic field pollution generated by air-core reactors has become a matter of public concern, and analysis of the distribution of magnetic field around air-core reactors is urgent and necessary.Current methods to analyse the magnetic field around air-core reactors include analytical calculation, numerical calculation and experimental measurement. The former two methods require large numbers of actual parameters of air-core reactors in advance, which are difficult to obtain; moreover, under complicated situations, it is difficult to obtain accurate results with these methods. Experimental measurement is the most fundamental and reliable method, while the cost of in-situ experiment is high and it is rarely studied. Small-scale experimental method is to reduce the original system and perform the experiments in a small space. It is a practical and reliable method which has significant applicable value.Therefore in this dissertation, the small-scale experimental technique is used as a novel way to assess the magnetic field around air-core reactors. Combined with the comparison of calculation results and experimental measurements, the scaling rules are put forward and validated. The prediction of shielding effects of aluminum plates using this method is also researched. To use this technique, the problems occurred frequently in the experiments are concluded, as well as the analysis of error. The small-scale experimental technique is convenient to perform in the lab, the materials used in the experiments are simple and the testing time is short. The reliability can also meet the requirements of engineering. The research in this dissertation provides references for the application of small-scale experimental technique, which has significant applicable value in the prediction of magnetic field around large sources.Then the small-scale experimental technique is also used to solve several practical issues in the prediction of magnetic field. Firstly, a simplified model of two current loops to approximate an air-core reactor is found as the optimal simplified model of an air-core reactor. Then the interaction of a set of reactors is studied by simulating different arrangement of air-core reactors in a substation, it is found that the arrangement of a downward-pointing equilateral triangle of three-phase air-core reactors produce the lowest magnetic field. At last the prediction of the magnetic field around busbars and their connections using small-scale experimental technique is verified.The calculation results and experimental measurements show that the small-scale experimental technique is an economical, easy, reliable, effective and practical way to simulate large magnetic field sources in the lab and obtain the characteristics of their magnetic field emissions. It is suggested that, if used adequately, the small-scale experimental technique could be of great use in predicting the distribution of magnetic field around large sources, which has a bright future.