换流站工频电磁场职业接触现状

Current status of occupational exposure to power frequency electromagnetic field in converter stations

目的分析换流站工频电磁场职业接触现状。方法采用典型抽样方法,选择正常运行的5个±500换流站和3个±800 kV换流站为研究对象。根据GBZ/T 189.3—2018《工作场所物理因素测量第3部分:1 Hz^100 kHz电场和磁场》检测工作场所工频电场强度和工频磁场强度,依据GBZ 2.2—2007《工作场所有害因素职业接触限值第2部分:物理因素》评价工频电场强度是否超标(8 h工作场所工频电场职业接触限值为5.000 kV/m),并根据国际非电离辐射防护委员会2010年推荐的50 Hz电场、磁场短时职业接触限值10.000 kV/m和1 000.00μT评价检测结果。结果换流站工作场所582个检测点的工频电场强度、工频磁场强度中位数和第0~100百分位数分别为4.342(0.001~12.003) kV/m和5.51(0.10~186.90)μT。换流站工作场所工频电场强度超标率为37.8%(220/582),集中在500 kV交流滤波器区和500 kV交流场区;其中有5个检测点的工频电场强度超过10.000 kV/m。所有检测点的磁通密度均未超过1 000.00μT。超高压区工频电场强度高于高压区(P<0.01);上述电压等级工频磁场强度比较,差异无统计学意义(P>0.05)。整流站、逆变站工频电场和工频磁场结果分别比较,差异均无统计学意义(P值均>0.05)。8个换流站作业人员工频电场强度8 h时间加权平均值为1.044~2.335 kV/m,均未超标。结论换流站作业人员可能短时间接触到超标的工频电场,但接触的工频电场8 h时间加权平均值符合标准要求,工频磁场暴露强度亦符合相关标准要求。

Objective To analyze the current status of occupational exposure to power frequency electromagnetic field in converter stations. Methods Eight converter stations with voltage levels of ±500 kV and ±800 kV within normal operation were selected as the research subjects using the typical sampling method. Power frequency electric field and power frequency magnetic field strengths were measured and calculated according to the GBZ/T 189.3-2018 Measurement of Physical Agents in Workplace--Part 3: Electric Field and Magnetic Field between 1 Hz and 100 kHz. The GBZ 2.2-2007 Occupational Exposure Limits for Hazardous Factors in the Workplace--Part 2: Physical Factors were used to evaluate whether the power frequency electric field strength exceeds the regulatory limit(the occupational exposure limit of power frequency electric field in 8 hours workplace is 5.000 kV/m). Meanwhile, the test results were evaluated according to the short-term occupational exposure limit of 50 Hz electric field and magnetic field recommended by the International Committee on Nonionizing Radiation Protection in 2010 that are 10.000 kV/m and 1 000.00 μT. Results The power frequency electric field and magnetic field strengths of 582 working environment detection points were measured. The median and 0-100 th percentile of power frequency electric field and power frequency magnetic field strength were 4.342(0.001-12.003) kV/m and 5.51(0.10-186.90) μT, respectively.The exceeding standard rate of power frequency electric field strength in converter station workplaces was 37.8%(220/582), which concentrated in 500 kV alternating current filter area and 500 kV alternating current field area. Among them, 5 detection points had power frequency electric field strength exceeding 10.000 kV/m. The magnetic flux density of all the detection points did not exceed 1 000.00 μT. The power frequency electric field strength in ultra-high voltage region was higher than that in high voltage region(P<0.01). There was no significant difference in power frequency magnetic field strength(P>0.05). There was no significant difference in power frequency electric field and magnetic field between rectifier stations and inverter stations(P>0.05). The 8 hours time weighted average(TWA) value of power frequency electric field strength of 8 converter station operators was 1.044-2.335 kV/m, which did not exceed the occupational exposure limit. Conclusion The converter station operators might be exposed to excessive power frequency electric fields for a short time, but the 8 hours TWA value of the power frequency electric field meets the requirements of standards, and the power frequency magnetic field exposure strength also meets the requirements of the relevant standards.