智能变电站变压器档位采用（）控制方式。
Adirect-with-normal-security
Bsbo-with-normal-security
Cdirect-with-enhancesecurity
Dsbo-with-enhancesecurity
Adirect-with-normal-security
Bsbo-with-normal-security
Cdirect-with-enhancesecurity
Dsbo-with-enhancesecurity