HVDC入地电流对地电场的影响规律及入地极定位  

THE INFLUENCE OF HVDC TRANSMISSION ON GEOELECTRIC FIELD AND LOCATING THE GROUNDING POLES

作　　者：章鑫 范晔[2] 叶青[2] 钱银苹 ZHANG Xin;FAN Ye;YE Qing;QIAN Yin-ping(Guangdong Earthquake Agency,Guangzhou 510070,China;China Earthquake Networks Center,Beijing 100036,China)

机构地区：[1]广东省地震局,广州510070 [2]中国地震台网中心,北京100036

出　　处：《地震地质》2022年第3期718-735,共18页Seismology and Geology

基　　金：广东省自然科学基金(2022A1515011105);国家自然科学基金(U2039206);中国地震科技计划项目(3JH-202001067)共同资助。

摘　　要：高压直流输电(HVDC)换流站的入地电流造成了地电场观测中的显著干扰,通常在入地极附近数百千米范围内会引起很大的阶变。但判断阶变来源于某个换流站的入地电流是较为困难的,一般需要借助高压直流线路对地磁场的影响数据来识别。文中以海驻线(海南藏族自治州—驻马店)、扎青线(扎鲁特—青州)和宝德线(宝鸡—德阳)为例,获取了3次典型干扰的响应数据,对3条线路周边58个地电场台站的数据展开分析,并使用山东大山台极低频数据作为对比案例。首先,解释了不同位置的台站对入地电流有不同的响应方式,即台站分别位于1个入地极附近、两极中间以及两极之间靠近一侧入地极这3种情况时,对应的3类响应分别为台阶状阶变、脉冲状响应和脉冲+半台阶状响应。然后,采用日变化幅度对高压直流输电干扰的阶变量进行校正,基于多台的电位差具有方向性的原理对入地极进行定位,判断入地电流的来源和换流站的大致位置。定位结果对海驻线、扎青线和宝德线的入地极位置都有较好的指向,结合多台的阶变合成矢量能够判断换流站的位置;此外,经日变化校正后的阶变幅度能显示入地极所在,可对定位结果进行补充。进一步建立入地电流的定量扩散电流模型,展示大电流入地时电位差的分布规律,判断入地电流的干扰范围和台站响应的阶变量。基于58个地电场台站和1个极低频台站的观测数据,文中给出了入地电流对周边地电场台站干扰的特点,可将其应用于实际观测中对HVDC干扰的数据校正。The grounding current of HVDC(high voltage direct current)converter station causes the most significant interference in the observation of geoelectric field,which usually causes a step change as 0.5~100mV/km within a range of hundreds of kilometers near the grounding pole.However,it is difficult to determine which converter station s grounding current causes the step change.Taking Hainanzhou-Zhumadian line,Zhalute-Qingzhou line and Baoji-Deyang line as examples,we obtain the response data of three typical disturbances,and calculate the step change using the data of 58 geoelectric stations around these three lines.To compare the interference situation,we referred the extremely low frequency data of Dashan station for comparison with their original curves.First,we explained the different response modes of the stations at different locations to the ground current.This means that when the stations locate near a ground electrode,in the middle of the two poles and near to one side of the ground electrode between the two poles,the corresponding three response types are:step response,pulse response and pulse+half step response,respectively.In particular,stations located in the middle of two poles but close to one pole are mainly affected by the near pole and less importantly affected by the other pole.Consequently,step response appears in the near pole stations,step recovery appears in the far pole stations,and the final result is in the form of step+pulse.Then,we use daily variation amplitude to correct the order variable of HVDC interference and locate the position of grounding pole by the principle that the potential difference of multiple stations has directivity,and then determine the source of grounding current and the approximate location of converter station.The step change after diurnal change correction shows a certain trend,which is shown as the quadratic attenuation of the source-station distance.The fitting of the step change observed by a wide range of geoelectric stations confirms this trend.The locating r

关 键 词：高压直流输电 入地极 地电场 多台定位 极低频 

分 类 号：P315.722[天文地球—地震学]