Development simulation and experiment study on UHF partial discharge sensor in GIS

A partial discharge (PD) sensor based on two-arm equiangular spiral antenna is designed and optimized in this research, and key parameters which mainly influence the performance of sensor are optimized. Through simulation and contrastive study, the key parameters' values are confirmed, which improves the sensor's performance to a great extent. To match the impedance of the sensor and the coaxial transmission line, a kind of micro strip impedance transformer which is of an exponentially gradual type is designed, the parameters of which are defined through simulation. Two improvement schemes for the designed transformer are also proposed to make an easy package and installation for the sensor and the transformer. Then, the physical model is made and tested. The results of simulation and test show good agreement, and verify that the sensors designed can meet the GIS internal partial discharge monitoring requirements well in bandwidth, performance and size, etc. The designed impedance transformer (IT) achieves impedance matching within the sensor and transmission line in ultra wideband range, and also enhances the sensitivity of the sensor.