基于匀场等效的非匀磁场曝露评估

Equivalent Uniform Magnetic Field Assessment Method for Non-Uniform Filed Exposure

过度曝露于电磁场会对人体健康造成不良影响,因此,电磁环境的准确评估是输变电工程建设与维护中的重要问题之一。目前,对工程作业人员实际承受的非匀磁场曝露缺少有效评估方法,现有研究多基于均匀磁场曝露假设展开,存在过评估。针对这一不足,本文以本专业人员熟悉的空心电抗器磁场评估为算例,提出了非匀磁场曝露评估的匀场等效法。搭建了符合中国成人平均身材尺寸的人体模型,结合空心电抗器周围磁场分布特点,计算人体模型位于不同曝露位置时体内感应电场极值与身体承受最大磁场的比值,确定非匀曝露系数。将非匀曝露系数与匀场曝露系数比较,得到空心电抗器周围的等效匀场分布。经计算,匀场等效法确定的曝露危险区域比传统方法小三分之一。本文研究的方法为评估实际输变电工程电磁环境提供了新思路。

Over exposure to the electromagnetic field may cause adverse health effect on human being. Hence, precise exposure assessment is one of the key issues in the construction and maintenance of the electric transmission and transformation projects. However, when assess the exposure in occupational environments, the uniform magnetic field distribution is often assumed. While in real situation a worker is typically exposed to non-uniform magnetic field. Focused on the overestimation caused by nowadays methods, this work put forward the equivalent uniform field method to deal with the realistic non-uniform field, and used the well-known magnetic field assessment around the air-core reactor as an example. The maximum induced electric field was calculated in different positions around the air-core reactor, based on a human body model with average figures of Chinese men. The non-uniform exposure factor was determined by divided the induced value to the maximum exposed magnetic field density. Then, the equivalent uniform magnetic field around the air-core reactor was computed by comparing the non-uniform exposure factor with the uniform exposure factor obtained in the same way. The example showed that the dangerous exposure region confirmed by this paper was one-third smaller compared with the traditional one. This work provides a new way to study the electromagnetic environment in real electric transmission and transformation projects.