On-line PD monitoring of Medium Voltage assets: an innovative approach to improve asset management

Abstract

One of the main causes of fault in Medium Voltage (MV) distribution grids is the breakdown of the insulation system of the electrical assets constituting the network. Such grids are composed of a large number of electrical apparatuses and each one of them is a possible cause of fault. Asset managers aim at increasing the reliability of the networks and decreasing the maintenance/ replacement costs of their parts. Thus it is necessary to have a thorough understanding of the overall status of each component in order to efficiently manage the assets. The focus of the condition assessment is turning toward smart solutions, integrable in networks, able to evaluate autonomously the condition of electrical assets and, only in case of anomalies, to request for man-operated support.On-line Partial Discharge (PD) monitoring has been identified as an effective diagnostic tool for electrical assets. It is not intrusive and it does not affect the working conditions of the grid apparatuses.In this paper, a novel approach to manage the MV grid assets through on-line PD monitoring is described. The main requisites of this solution are related to the characteristics of the distribution grids: easy to install, non-invasive, low cost and reliable. The technological solution is comprehensively described, focusing mainly on the automatic acquisition, noise rejection and processing of PD data and the recognition of increasing PD trends as a tool to trigger warning signals. The effectiveness is shown by means of case studies about various MV pieces of equipment, particularly switchgears and RMU.