Abstract
Current measurement is a key part of the monitoring system for power transmission lines. Compared with the conventional current sensor, the distributed, self-powered and contactless current sensor has great advantages of safety and reliability. By integrating the current sensing function and the energy harvesting function of current transformer (CT), a time-multiplexed self-powered wireless sensor that can measure the power transmission line current is presented in this paper. Two operating modes of CT, including current sensing mode and energy harvesting mode, are analyzed in detail. Through the design of mode-switching circuit, harvesting circuit and measurement circuit are isolated using only one CT secondary coil, which eliminates the interference between energy harvesting and current measurement. Thus, the accurate measurement in the current sensing mode and the maximum energy collection in the energy harvesting mode are both realized, all of which simplify the online power transmission line monitoring. The designed time-multiplexed working mode allows the sensor to work at a lower transmission line current, at the expense of a lower working frequency. Finally, the proposed sensor is verified by experiments.
Highlights
Compared with the conventional current sensor, the distributed, self-powered and contactless current sensor has great advantages of safety and reliability
The mode-switching circuit is designed to isolate the harvesting circuit and the measurement circuit, making the sensor work in time-multiplexed mode, which eliminates the interference between energy harvesting and current measurement
The accurate current measurement and the maximum energy collection are realized through only one current transformer (CT) secondary coil instead of two coils
Summary
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