An Implementation Method of Energy Harvesting CT Based on Double-Winding Control

When the online monitoring equipment is supplied by the traditional current transformer (CT), it is easy to be affected by the large-scale fluctuation of the transmission line current. This fluctuation will not only lead to insufficient CT power when the current of the transmission line is small, but also make the CT magnetic core saturated at high current. In order to solve the above problems, a method for realizing the energy harvesting transformer based on double-winding control is proposed in this paper. One set of coils is connected to the load side, and the other set of coils is connected to the impedance conversion circuit for reactive power adjustment. According to the magnitude of the transmission line current, the CT output impedance is controlled to work in different modes to realize the dynamic adjustment from capacitive to inductive. So as that the CT maintains a stable output voltage when the transmission line current varies in a large range. Due to the decoupling of the two coil circuits, the control of the impedance adjustment is simple. The double-winding CT is carried out through simulation. The effectiveness of the proposed scheme is verified by simulation results.