Partial discharges (PD) occur as a result of dielectric breakdown in electrical insulation under high voltage stress. PD activity, once initiated, causes chemical and physical degradation of insulating material and can lead to catastrophic failure. Early warning of PD activity and localisation is considered essential to ensure the reliable operation over the long term of high voltage equipment including cables, cable accessories and switchgear. PD detection in high voltage cable and cable accessories is usually carried out with test objects offline, requiring potentially significant interruption of service. An online detection system is preferable but difficult to calibrate apparent charge magnitudes due to changes in real distribution network loading and topologies. An online PD detection system with continuous calibration has been developed to determine the apparent charge magnitudes of PD activity and locations in a section of in-service distribution network with high monitoring frequency and no requirement to take cables off line. Results of the on-line PD monitoring system in a typical urban distribution network in Spain are presented. System components including the online calibration pulse injector, capacitive sensors for high frequency PD pulse detection, and data acquisition, processing and communication components at each monitoring site are presented.

On-line measurement and monitoring of partial discharges in an MV cable system, including terminations and joints, is a challenging subject because it interacts with other components of the distribution network such as ring main units. The stochastic nature of partial discharges, the different configurations of the network, the external noise and the lack of standard recommendations have consequentially made the quantification of this phenomena more difficult. This paper is an attempt to investigate the behaviour of a theoretical pulse propagation and a real partial discharge in different circuits with almost the same configuration, that can be easily configured in a real Smart Grid laboratory. Several experiments and measurements were performed in order to compare these circuits and to find a factor that represents the influence of different circuit components to use as a reference or calibration to ensure the validity of further measurements.

Partial discharges (PD) occur as a result of dielectric breakdown in electrical insulation under high voltage stress. They can be caused by the presence of gas pockets or voids in solid insulation / gas bubbles in liquid insulators (internal), insulator surface imperfections / irregularities (superficial) and around an electrode in gas (corona). PD activity, once initiated, causes chemical and physical degradation of insulating material and can lead to catastrophic failure. Early warning of PD activity and localisation is considered essential to ensure the long term reliable operation of high voltage equipment including cables, cable accessories and switchgear.PD detection in high voltage cable and cable accessories is usually carried out with test objects offline, requiring potentially significant interruption of service. An online detection system is preferable but difficult to calibrate apparent charge magnitudes due to changes in real distribution network loading and topologies. An online PD monitoring system with continuous calibration has been developed to determine the apparent charge magnitudes of PD activity and locations in a section of an in-service distribution network. System components including the online calibration pulse injector, capacitive sensors for high frequency PD pulse detection, and data acquisition, processing and communication components at each monitoring site will be presented. Long term parameter trending data from the ongoing trial in a typical urban distribution network in Spain will also be presented.

No abstract

No abstract