Focusing on the application of an optimized current injection control system for low-voltage type current transformer banding measurement, this paper aims to achieve accurate autonomous modulation of industrial frequency current under dynamic working conditions. A charged circuit modulation system based on sinusoidal pulse width modulation (SPWM) technology is constructed, which generates an AC signal through an inverter circuit and works in concert with the transformer to quickly and accurately inject current into the measured circuit. For the delay problem, the effects of filter circuit and actuator response are analyzed, and double closed-loop control strategy are adopted to effectively reduce the filtering pressure and decrease the hysteresis delay. The system stability is verified using the root trajectory method, and the proportional-integral(PI) control parameters are optimized by the frequency domain analysis method. Simulink simulation results show that the injected current control system realizes autonomous modulation of the industrial frequency current in the range of 1% to 120% of the rated current. Finally, the full-range regulation of the test loop current under charged conditions is successfully achieved, providing a reliable solution for high-precision current measurement in power system.
