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Pole Designs Optimize Aesthetics, Feasibility & Cost

June 22, 2018 • ARTICLE ARCHIVE, Utility Practice & Experience
PPC Insulators

In many countries, construction of new HV and EHV overhead lines has triggered divisive public debate, with particular resistance against the use of traditional lattice towers. In the face of this, one way to promote greater acceptance and also minimize the impact of new lines is by using alternatives such as compact and ‘designer’ structures. This edited contribution by Alexander Braun of Europoles in Germany, offered an overview on the status of alternative pole designs with a focus on achieving the right balance between the competing demands of design, operational safety, public acceptance and cost-effectiveness.


Grid Expansion & Politics

The shift in energy generation from traditional large-scale power plants toward smaller renewable energy producers combined with geographic changes in production hubs and new cross-border interconnections have required comprehensive restructuring of power grids, especially in the HV and EHV segments. Grid operators these days not only have to meet statutory requirements (including security of supply, non-discriminatory access as well as economic set-up and operation); they also have to ensure that the people most affected recognize the necessity for and accept new line routes. That is why planning and construction of overhead lines today has become a process largely defined by politics and often involves decision-making at the highest levels of government.

Public opposition plays a key role, given reservations about the construction of new power lines and the possible effects on the environment and on people (i.e. electromagnetic field, impact on tourism and changes to the landscape). Apart from an effective communication strategy, early involvement of those affected and an open approach to objections and concerns, there are also various technical options that can help promote acceptance of new power infrastructure. One option is to use technologies such as full underground cabling, DC transmission (in combination with buried cable) or low-sag cable. However, these alternatives are constrained by technical risks since they have not yet been proven over long-term service experience. In addition, the high costs involved in extensive groundwork present a serious drawback when it comes to buried cable.

An important element of grid expansion is maximizing use of existing corridors and, where possible, upgrading existing power lines. Grid expansions enjoy the highest acceptance levels in these areas and approvals are generally issued sooner. In order to encourage greater acceptance, better utilize existing corridors and minimize impact of new lines, alternative designs such as compact lines have been used for decades. More recently, international architectural competitions (e.g. as held by Terna in Italy, National Grid in the UK, RTE in France, etc.) have also highlighted new, more acceptable pole designs.

Achieving Balance Between Design, Public Acceptance, Technical Safety & Cost

In practical terms, any new pole structures have to meet all the various requirements imposed, particularly by grid operators themselves. In this context, design can sometimes play a subordinate role. What is equally and often more important are technical safety, cost-effectiveness and operating costs (including maintenance costs). The challenge then is to meet all these requirements while at the same time utilizing an aesthetically pleasing design, i.e. one that guarantees safe operation of lines that are also economical to build and run.

Fig. 1: ‘Magic Triangle’ of aesthetic pole design. pole design Pole Designs Optimize Aesthetics, Feasibility & Cost Screen Shot 2016 04 06 at 3

Fig. 1: ‘Magic Triangle’ of aesthetic pole design.
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This process has to take account of a lot of different variables and stakeholder interests, a selection of which are listed below:

Public Acceptance:

• Lower height;
• Modern infrastructure;
• Possibility to ‘have a choice’;
• Narrower right-of-way;
• Reduced EM fields;
• Reduced impact on landscape;
• Participation in decision-making;
• Pleasing design.

Technical Feasibility:

• National standards;
• Structural stability requirements;
• Ageing & fatigue;
• Durability;
• Corrosion protection;
• Lifetime >80 years;
• Earthing & lightning protection;
• Induced currents;
• Electrical clearance;
• Electrical requirements;
• Electromagnetic fields.

Cost Efficiency:

• Test programs;
• Development costs;
• External consultants;
• Training costs;
• Costs for extra design;
• Pole costs;
• Foundation costs;
• Marketing costs.

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