Purpose/Aim
The concept of smart grid has attracted extensive attention since it was put forward, and has gradually become the development trend of the power grid grind. The realization of smart grid needs the support of various technologies, among which advanced sensing technology plays a vital role in the monitoring of various parameters of smart grid. As one of the most basic state variables of smart grid, its on-line monitoring is very important for the stable operation of smart grid. At present, there is no mature detection method for the monitoring of transient currents such as lightning, operation, power frequency overcurrent and short-circuit current in the line. Therefore, the research of broadband current sensing device has important research value for improving current on-line monitoring.
Experimental/Modeling methods
In this paper, a very broad band tunneling magnetoresistive current sensing device is developed. By simplifying the circuit and optimizing the design of the circuit board, the stray parameters of the sensing device circuit are reduced. The high-frequency electromagnetic induction of the sensor is reduced by using magnetic collector ring, reducing the wiring circuit area of circuit board and electromagnetic shielding design. The main performance parameters such as bandwidth, range and linearity of the sensor are measured.
Results/discussion
The bandwidth of the designed UHF current sensor reaches 8MHz, at this time, the amplitude response is 0.61dB and the phase lag is 42.8°. By using the magnetic collector ring, the adverse effect of the magnetic field of the circuit board perpendicular to the sensitive axis of the sensor chip on the high-frequency performance can be limited.
Conclusions
Sensor stray parameters and high-frequency electromagnetic induction will affect the high-frequency characteristics of the sensing and measurement system, in particular, the parasitic capacitance and loop induced voltage of the circuit board from the sensor chip to the instrument amplifier will seriously affect the high-frequency performance of the sensor. The sensing and measuring equipment shall be designed for high frequency and electromagnetic compatibility. 
 

smart grid;,TMR,current sensor,wide bandwidth