An arrester resistive current calculation method based on the orthogonal transform

The invention discloses a method for calculating resistive current of an arrester based on orthogonal transformation. The method comprises the following steps of: defining I , I , I , and U respectively representing a capacitive current vector value, a resistive current vector value, a full current vector value and a voltage vector value, i(t)=sqrt(2)*Icos(2pif0t+phi); and if no harmonic component is present, adopting an algorithm which comprises the following substeps of: 1) performing discrete sampling on i(t) to obtain a formula (1); 2) constructing a reference signal to obtain a formula (2); 3) multiplying the formula (1) by the formula (2) to obtain a formula (3); 4) solving a phase value of the formula (3); and 5) calculating the resistive current; and if the harmonic component is present or power frequency has deviation, correcting the 1) and 2) in the step 2. In the algorithm, only a full current signal is needed, a full voltage signal and other extra conditions are not needed, the resistive current can be solved, and the cost is reduced; moreover, harmonic and noise interference can be effectively suppressed, and the precision is improved.