Sensors for on-line PD detection in MV power cables and their locations in substations

Abstract

For developing a system capable of on-line detecting and localizing PDs in MV power cables, the choice of the sensor type is crucial. Sensors for detecting PDs can be divided into two main groups: capacitive and inductive sensors. In this paper, the advantages and disadvantages of these two types of sensors are discussed for on-line application. In multi-conductor cables, e.g. a three-phase belted cable, it is essential to distinguish the different propagation channels. When the cable is under normal operating conditions, all three the phases are energized simultaneously, implying that the PD pulses are propagating through two distinctive propagation channels: the Phase-to-Phase (PP) channel and the Shield-to-Phase (SP) channel. Measuring sensors can therefore also be subdivided with respect to the detected channel. If sensors can detect signals in all three conductors separately, both SP and PP channels are obtained. In this paper different positions in a substation for placing sensors are evaluated, with respect to the measured propagation channels, signaland interference sensitivity, safety and practical applicability.

Wavelet-based de-noising of on-line PD signals captured by Pearson coil in covered-conductor overhead distribution networks

“…It has many advantages as compared to traditional condition monitoring systems. The major advantages are continuous monitoring, no disruption of power supply and system is working under normal conditions [26]. However, installing on-line on-site PD monitoring system is bit challenging because system is working at normal conditions and the noise produced by other instruments cannot be neglected.…”

A centralized condition monitoring system for MV power cables based on on-line partial discharge detection and location

“…The sensor must be installed in an existing network, preferably during operation and may not introduce a safety risk during installation or operation. Therefore the choice was made to use inductive toroidal sensors, which can be clamped around the earth lead or the shielded cable itself, [8]. This has some important advantages: 1.…”

Effect of Cable Load Impedance on Coupling Schemes for MV Power Line Communication

“…A survey of MV systems used in The Netherlands showed that for the majority of the substations, coupling sites are accessible for injecting or detecting signals by placing a coil either around a phase conductor at a cable end (where the earth screen is still present), or around the earth connection nearby the cable [4]. This inductive coupling scheme is basically a weakly coupled transformer.…”

“…Sixteen cables in life circuits from two Dutch utilities have been tested at both sides to determine the noise level [4]. Commercially available inductive sensors with a bandwidth of several tens of megahertz were positioned at various locations interesting for PD detection, and accessible also for power line communication.…”

“…In both cases the secondary current is measured over the same cable screen as injection takes place. The secondary current can be calculated from (4) where represents the impedance of the cable containing the current probes; the summation in the denominator includes all impedances closing the current path. The substations shown in Fig.…”