Abstract: The secondary voltage signal output by electronic capacitive voltage transformer in the primary and

secondary fusion equipment is very weak，which is easy to be interfered by high-order harmonics，resulting in

unstable signal transmission. In order to solve these problems，a high-order and high-precision filter based on

Sallen-Key was proposed to suppress harmonics and reduce the interference to the working signals. Firstly，the

working principle of the transformer was analyzed. Then，based on the principle and the working frequency band of

the primary and secondary fusion equipment，the integration circuit and filter circuit were studied and designed with Matlab/Simulink simulation software. Finally，the filtering circuit was optimized and the whole circuit was

simulated. The results show that the optimized circuit can suppress the interference of high-order harmonics more

effectively and ensure the stable output of fundamental wave.

      Key words: primary and secondary fusion equipment；electronic voltage transformers；filter circuit；frequency

characteristics