HVDC Light is the most recent HVDC technology based on Voltage Source Converters (VSC) and extruded DC cables with power units up to 200 MW. HVDC Light converters include Insulated Gate Bipolar Transistors (IGBT’s) and operate with high frequency Pulse Width Modulation (PWM) in order to get high speed control of both active and reactive power. HVDC Light cable is a cable with insulation of extr...

Applications of on-line PD spot testing and monitoring for in service power cables are presented. The motivation and advantages of the on-line approach to the cable insulation assessment are covered. The different aspects of PD testing are discussed: detection, location and continuous monitoring. The test techniques for different types of transmission and distribution cable circuit are shown wi...

The variations in the low frequency dielectric spectra of mass impregnated insulation depending on its moisture content have been investigated. For the calibration purposes a number of the impregnated paper samples was kept in the desiccators where different relative humidities were maintained. Thus obtained moisture content in the samples ranged from 1 % up to 6 %. The variations of the comple...

In this study, an improved trapping/detrapping model was used to simulate the charge dynamics in cross-linked polyethylene peelings from different-year aged cables. Injection barrier of trapping parameters was estimated by the model fitted to experimental data for each type of sample. Moreover, dc breakdown tests were operated on those samples. It has been found that the dc breakdown strength o...

In high voltage power cable system, partial discharge (PD) is a common phenomenon which reflects the degradation of insulation. When partial discharge happens inside the cable, leakage current will flow through the grounded conductor. To couple the partial discharge current, one feasible and effective method is placing a clamp-on high frequency current transformer around the grounded strap. In ...

It is well known that existence and accumulation of space charge within the insulating material poses threat to the reliability in the operation of dc power cables. When the cables are loaded under high voltage direct current (HVDC), temperature gradient is developed across the insulation material. In this paper, commercial ac XLPE power cables were used under an application voltage of 80 kV dc...

Defects inside insulation of HV XLPE cable accessories can lead to partial discharge (PD) activity. When PD activity happens, leakage current may flow through the grounded line. To acquire the PD current signal, one practicable and effective method is placing a high frequency current transformer (HFCT) winding the grounded line. In order to measure the insulation degradation, a partial discharg...

Impulse over-voltages are very common phenomena in electric power systems. Switching impulses are created by switching surges or local faults while lightning impulses are due to lightning strikes to overhead lines. Both impulses can travel as waves in the system, damaging insulation components and equipment. This paper shows that there may well be a reduction in electric field strength of the i...