高压直流输电干扰对江油地震台、盐源地震台地电场优势方位角的影响

Analysis of the influence of the HVDC transmission interference on the dominant azimuth of geoelectric field at Jiangyou Seismic Station and Yanyuan Seismic Station

利用大地电场优势方位角方法对四川江油地震台、盐源地震台地电场进行研究,选取2个台站受高压直流输电干扰时段的地电场原始日变化分钟值数据,进行计算和统计分析。研究发现:①2个台站不同日期受干扰的幅度、起止时间不同,如1天内可能出现多次高压直流输电干扰事件,干扰导致地电场日变数据曲线呈现方波形态,此外,还可能存在持续多日的高压直流输电干扰,地电场观测曲线表现出持续性方波变化;②高压直流输电干扰在台站不同测向上出现的时间一致,如江油地震台、盐源地震台地电场长极距三测向观测曲线均在同一时间表现出跃变;③在2个台站受高压直流输电干扰的当天,优势方位角均显示出减小的变化特征;④2个台站在持续性干扰时段内优势方位角的趋势性变化不同,江油地震台为致密的异常变化,而盐源地震台为下降式波动变化。

The dominant azimuth method of geoelectric field is used to study the geoelectric field of Jiangyou Seismic Station and Yanyuan Seismic Station in Sichuan Province.The original daily variation minute data of two stations during the period of HVDC transmission interference are selected for calculation and statistical analysis.It is found that:1.The amplitude,start and end time of interference in different days of the two stations are different.For example,there may be multiple HVDC transmission interference events in one day,as a result,the daily variation data shows a square wave shape.In addition,there may be HVDC transmission interference lasting for many days,which shows a continuous square wave change on the geoelectric field time series curve.2.The occurrence time of HVDC transmission in different direction finding of the station is consistent,for example,the observation curves of geoelectric field data at Jiangyou and Yanyuan stations show a jump at the same time.3.On the day when the two stations are interfered by HVDC transmission,both of the dominant azimuths at Jiangyou and Yanyuan stations show a decreasing change.4.The trend changes of the dominant azimuth of the two stations during the continuous interference period is different.The Jiangyou Station shows tight abnormal changes,while the Yanyuan Station shows downward fluctuations.