Four high-level tutorials will be given by professors during the Sunday afternoon of June 20th, 2011 for a limited number of people:
- T1: Towards an underground distribution network
- T2: Accessories for high voltage extruded cables
- T3: Electrical modelling of underground links
- T4: Service experience of high voltage underground and submarine power cables
Registration to these tutorials may be made by use of the registration form attached or through internet.
T1: Towards an underground distribution network
By Alain DOULET, Former Technical Manager, ERDF
Environmental constraints, local pressures on techniques for building distribution networks are becoming commonplace. This can lead to the replacement of overhead techniques by underground techniques for the creation of new networks but it can also include transforming existing overhead lines into underground networks.
These guidelines may concern urban, suburban, but also rural networks. Yet, an underground network should not be considered as an overhead network buried underground. The choice of an underground network structure largely impacts the whole traditional business chain of the Distributor: network design, engineering, operations, maintenance. Beyond that, important aspects are affected by such an option: regulatory matters, for workers security, stakeholders and for the public, competencies. Approach to the issue of quality - the number and duration of predictable and unpredictable cuts - is strongly impacted. Finally, it is necessary to establish an economic balance upstream of any decision in order to identify the resources needed for the deployment of such a choice.
The tutorial will aim to give an overview of all these questions essentially as a tool to help in the decision making process for technicians to build such approaches to change, then to describe some efficient solutions as a starter for a possible discussion.
T2: Accessories for high voltage extruded cables
By Henk GEENE, Prysmian Cables and Systems B.V.
Since the introduction of HV extruded cable systems more than 30 years ago, significant improvements have been made in the design of its accessories.
Nowadays, the market has almost completely moved towards the use of pre-molded (factory made and tested) accessories. Although with these accessories the reliability of extruded cable systems has significantly improved, there are still important aspects that need to be taken into account during its design and installation. The Tutorial will focus on these accessory related aspects and will include the results of recent work performed by CIGRE.
Topics to be discussed:
- The position of the different accessory types in cable networks
- Overview of accessory concepts in the market
- Accessory design aspects and the possible critical spots (conductor connection, interfaces, covering)
- Installation conditions (buried, tunnels, manholes)
- Workmanship of accessories
- Trends in accessory development (diagnostics, dry types…)
T3: Electrical modelling of underground links
By Éric DORISON, EDF R&D
The tutorial involves 4 parts:
- The first one is dedicated to the derivation of cable primary impedances from Maxwell’s equations, focusing on simplifying assumptions. Models for transients studies are presented and a simple model, suitable to power frequency studies, is given.
- The second part deals with large cross section core and composite screens designs, stressing power frequency Joule losses calculation.
- The third part is devoted to sequence impedances calculations, taking into account screen bonding techniques.
- Finally, some concerns with special screen bonding designs are addressed, particularly earth potential rises during single-phase faults.
- Comparison of calculated and measured relevant parameters are discussed where available.
T4: Service experience of high voltage under-ground and submarine power cables
By Robert ROSEVEAR, Southampton Dielectric Consultant Ltd
In recent years, significant quantities of land and submarine cables and accessories have been installed and the associated technology and laying techniques have matured and evolved. With the increasing demands on electrical power transmission and distribution systems, significant quantities of cable are currently being installed.
In 2008, CIGRE WG B1.10 completed a survey to collect and analyse data relating to the installed quantities of underground and submarine cable systems rated at 60 kV and above together with the service experience and the performance of existing underground and submarine cable systems. The CIGRE Technical Brochure TB 379 summarizing the findings was published in April 2009. The tutorial is based on this work. A 5 year period ending december 2005 has been considered for land cables compared to a 15 year period ending similarly for submarine cables.The previous statistics published some twenty years ago have therefore been updated and some emerging trends identified.