A novel gas insulated switchgear (GIS) partial discharge (PD) sensor with integrated optical fiber and ultrahigh frequency (UHF) method is developed in this paper. The integrated sensor is formed by placing an optical fiber on the surface of the UHF sensor. The novel sensor can be mounted inside the GIS and measure the PD through optical and UHF signals at the same time. The validity and sensitivity of the sensor are proved by experiments on a physical 110 kV GIS. This PD detection sensor solves the problem that the optical fiber is difficult to be mounted inside GIS and provides a novel method for PD detection in GIS.

Detecting partial discharge (PD) in gas-insulated switchgear (GIS) is an effective way to diagnose the insulation state of GIS. When PD occurs in GIS, optical and electromagnetic signals will be emitted from the discharge source. PD can be detected by analyzing these signals. At present, the ultrahigh-frequency (UHF) method is one of the most popular methods for detecting the PD in GIS. However, the optical method has not been in the field due to the problem of mounting optical sensor into GIS, even though it has higher sensitivity and better anti-interference performance. To settle this problem, a novel GIS PD detection sensor integrated with the optical fiber and UHF method is developed in this paper, which can fully utilize the advantages both of UHF and optical methods. The simulation results indicate that the integrated sensor can be mounted into GIS on the premise of not affecting the electric field distribution in GIS. In addition, the integrated sensor has a good UHF performance. The PD signals of typical defects at several locations were measured in a physical GIS using the integrated sensor. The results show that the integrated sensor can detect the optical and UHF signals induced by PD at the same time. The optical method has higher sensitivity than the UHF method for the protrusion defect. The amplitude and the number of the optical signals induced by PD clearly decrease with the increase in the detection distance. The studies in this paper are helpful to improve the accuracy and sensitivity of PD detection in GIS on site.

Partial discharge (PD) detection from protrusion defects is performed in an actual gas-insulated switchgears (GISs) based on a built-in sensor integrated with fluorescent fiber and ultrahigh frequency (UHF) antenna. The characteristics of both optical and UHF signals are analyzed in terms of inception voltage, pulse distribution, and statistical characteristics including the phase-resolved partial discharge (PRPD) pattern and PD number. In the experiment, protrusions with different curvatures are adopted to investigate the reason for the differences in the characteristics of UHF and optical signals. The results show that UHF and optical methods have different detection sensitivity for different discharge types owing to the different energies of electromagnetic waves and optical signals radiated in different discharge types. The optical method can easily detect avalanche discharge, while the UHF method can easily detect streamer discharge. This difference leads to the difference of the PD characteristics obtained by the two partial methods. For example, for the PD of small curvature protrusions, the PD inception voltage (PDIV) of the optical method is lower than that of the UHF method, because the defect triggers avalanche discharge. Moreover, the optical and UHF signal pulses are not always simultaneous in the time domain because they detect different discharge types. The PRPD patterns obtained by the optical method have a wider phase distribution than the UHF method because the optical method can detect avalanche discharge under low voltage.

A partial discharge (PD) detection method for SF6 insulated inverted current transformers (SIICTs) adopting inner shield case as ultra-high frequency (UHF) sensor is proposed in this paper. Inner shield case is a component of the SF6 insulated inverted current transformer. Its structure is similar to that of an antenna and can be used as UHF sensor to measure the PD UHF signal. A 110kV current transformer is used as experimental object and the voltage standing-wave ratio (VSWR) of the inner shield case is calculated. The validity and sensitivity of this method are proved by experiments with AC voltage. This PD detection method solves the problem that the UHF sensor is difficult to be mounted inside current transformers and provides a novel method for PD detection of SF6 insulated inverted current transformers.

The faults of electrical equipment are mainly generated by electrical and mechanical defects, which are usually detected by external ultrasonic and vibration sensors respectively. To improve the accuracy and efficiency of the diagnosis, a novel ultrasound-vibration composite sensor(UVCS) which can detect ultrasound and vibration acceleration signals synchronously at the same place, is proposed and developed scientifically in this paper. The working principle of UVCS is based on the combination of the mass and the backing as well as the steel base and matching layer, and the structure is improved reasonably. Furthermore, the ultrasound and vibration signals can be separated by filtering. In addition, the test results on a 110kV GIS show the high precision and reliability of UVCS and illustrate the superiority in practical application.