School of Electrical and Information Engineering, Changsha University of Science & Technology, Changsha 410114, China

Aiming at the problems such as easy saturation of magnetic circuit and low acquired power of the widely used on-line power acquiring device of current transformer, this paper proposes an on-line power acquiring method combining dual magnetic circuit topology with resonant power control. In the dual magnetic circuit structure, a two-semicircle magnetic core is installed on the transmission line, and the excitation inductance in the magnetic circuit is resonant in parallel with the capacitance through the secondary-side connection capacitor, which increases the impedance value of the magnetic circuit. Thus, the current on the line is controlled to flow more into the other magnetic circuit coil of the dual magnetic circuit, through which the internal impedance is matched with the value of the external load, and the maximum power is obtained. Based on this method, an anti-saturation strategy of magnetic core controlled by excitation inductor and resonant capacitor is put forward, which makes the device keep high acquired power while work normally. The correctness of the method and the applicability for the circuit harmonic are verified by the joint simulation of Maxwell and Simplorer. The preliminary test shows that the power acquired by the dual magnetic circuit can meet the requirement of monitoring equipment of high voltage transmission line.