Study Of High Frequency Current Transformer For Online Monitoring Of Partial Discharge

In recent years, the malfunction of isolation of the stator coils becomes the major affect of power facility problems. In order to establish the reliability of power systems, people used to stop the function and give a thorough examination to power systems in the past, which also has side effects.In order to lower the cost, one solution is to exactly grip the deterioration situation of power systems while they are steadily running. Partial discharge(PD) which can measure the aging situation, becomes more and more recognized. Nowadays, measurement and analyzing of PD signals now becomes one of the major solutions of isolation monitoring.The monitoring of partial discharge is realized by measuring the phenomena happen during discharging. While discharging, current pulses, heat, light, compounds etc. will be created. Through the measurement of these phenomena, people were managed to get total understanding on the aging situation of power systems. The pulse current monitoring is a high sensitivity and simple solution which monitors the PD pulse current. One of its most important parts is current transformers.The most important parameters of current transformers are bandwidth and sensitivity. In order to higher the accuracy. Current transformers for PD monitoring require high sensitivity, extra high bandwidth and intense attenuation to low frequency inputs. In this paper I will investigate the principle of current transformers, discuss several solutions of error compensation and analyze the model of current transformers. After plenty of experiments, a high frequency current transformer based on Rogowski coil will be designed. This current transformer has high sensitivity, extra high bandwidth and meets all requirements by PD monitoring.