High frequency partial discharge measurement of straight power cable joint

Existing methods of measuring partial discharge of cable joints need to change the inherent structure of the joints, or the measurement sensitivity is low. In this paper, based on the principle of capacitive coupling, a method for partial discharge measurement of straight cable joint is proposed, and the corresponding measurement system is established. After the efficiency of the measurement method is proved by the computer simulation, a laboratory test is carried out to investigate its performance. In a real 35kV straight cable joint, a spike defect is preset and contrast test of partial discharge is carried out. The test result shows that the sensitivity of the straight cable joint PD measurement system is better than 10pC. And the phase resolved partial discharge patterns similarity of the proposed measurement system with the DST-4 partial discharge detector is as high as 0.9. Thus, the experiment demonstrates the validity of the method. The proposed method has the advantages of high measurement sensitivity, strong anti - interference ability and simple structure of the sensor compared with the existing measurement method without undermining the inherent structure of the cable joint.