ABSTRACT
The fundamental principle of overvoltage signals restored from leakage current of capacitive devices is as followed. Typically, capacitive bushing can be approximately represented by an equivalent capacitance C. When the grid is invaded by overvoltage u, there will be current i flowing through the bushing tap. The following formula shows the rationale:
3 COMPOUND INTEGRATOR DESIGN
Traditional Rogowski coil can be separated by its working status; self-integral working and out-integral working. The output voltage from the sensing head of self-integral Rogowski coil is proportional to measured current. The output voltage from the sensing head of out-integral Rogowski coil is the differential of measured current. The signal has to be restored by an external integration circuit. In our study, we designed a compound integrator combined with self-integrator and outintegrator. The compound integrator can keep the sensitivity, at the same time expand the working bandwidth, and realize required functionalities of the sensor.
