TERNA, the transmission system operator in Italy, is currently ranked seventh in the world in terms of transmission system length. In addition to ownership of the majority of the country’s transmission system, TERNA is responsible for the design, construction and operations that extends 62,000 km (38,525 miles). To maintain a secure, reliable and cost-effective supply of electrical energy in Italy, the system is interconnected with 18 circuits in neighboring countries, which form the European transmission system (ENTSTO-E).
A further strategy to ensure a reliable flow of energy is to minimize the impact of power outages by reducing the number, frequency and duration of such events, which is a daunting challenge. Power outages are unpredictable and can be caused by many weather-related factors. Events such as ice storms, thunderstorms and high winds are responsible for a large percentage of power outages in Italy and in most parts of the world.
Power outages can last from a few minutes to many days, depending on the severity of damage. When such an event occurs, the utility’s emergency-response teams are summoned to duty to repair the damage and restore supplies as quickly as possible. This task often can be difficult, resulting in teams working in demanding and dangerous conditions. Apart from inconvenience to the customer, these disruptive events have a financial impact on the utility. In addition to the cost of the emergency-response teams and system fault repairs, outages also result in a loss of revenue and may even require the utility to pay penalties imposed by industry regulators for the number and length of supply interruptions.
Annually, TERNA undertakes an exhaustive planning procedure to prepare the national transmission grid development plan. This formal document establishes a rolling 10-year planning horizon for the utility’s transmission system, specifying the goals and objectives to be achieved within the planning horizon. One of the key objectives in TERNA’s plan is to cope with system emergencies to effectively deliver and improve system reliability. TERNA’s aim is to improve its response to emergency situations created by system outages, so that it can address these events rapidly and more effectively.
Transmission Tower Solution
The Italian topography and high hydrogeological risks can cause the failure of the transmission line’s supporting towers, and one solution is for TERNA to stockpile spare tower parts to ensure rapid deployment. However, this solution is not considered practical or cost-effective because it would require TERNA to store many tower types and a large number of components.
An alternative and more expedient solution is a temporary tower, specially designed for quick installation, offering a lightweight, durable and versatile solution. These towers can be delivered to any site and erected within a couple of hours using minimal equipment, without the need for detailed site engineering.
A temporary tower enables the faulted transmission line to be repaired and reenergized, providing the utility the opportunity to plan and rebuild the tower at the most convenient time, without an extended supply interruption. During the permanent reconstruction work, the conductors are transferred to the new tower, allowing the temporary tower to be dismantled and the components returned to their storage containers to await the next emergency.
Temporary towers are not only used for tower failures, they also can be used on routine maintenance work when towers need to be replaced or repositioned. Additional applications include their use as temporary structural supports, such as a transmission line bypass of a construction site.