In terms of current measurement in new power systems, tunneling magnetoresistance magnetic sensor arrays have advantages that can well meet the needs of current measurement. Firstly, the development status of tunneling magnetoresistance array technology in power system measurement and the measurement principle of tunneling magnetoresistance are introduced. The analysis focuses on the current measurement using a magnetic array sensor installed on a conductor with a circular cross-section. The impact of eccentricity on the measurement error of the magnetic array current sensor is analyzed when the conductor is eccentric. The integration method is used to obtain a more accurate measured current value. By using a measurement scheme with six sensors arranged in a circular pattern, the relationship between the sensor output voltage and the measured current is established. Finally, simulation and experiments have shown that the measurement error and accuracy of the adopted method meet the requirements of engineering practice, providing reliable data support for the state monitoring of modern smart grid operation.